Patent Application
20250132401
This application claims priority to and the benefit of Korean Patent Application No. 10-2023-0143196 filed in the Korean Intellectual Property Office on Oct. 24, 2023, the entire contents of which are incorporated herein by reference.
Embodiments relate to an additive for a rechargeable lithium battery and a rechargeable lithium battery including the same.
A rechargeable lithium battery may be recharged and may have three or more times as high energy density per unit weight as a lead storage battery, nickel-cadmium battery, nickel hydrogen battery, nickel zinc battery, or the like. It may also be charged at a high rate and thus, may be commercially manufactured for a laptop, a cell phone, an electric tool, an electric bike, or the like, and research on improvement of additional energy density have been actively made.
The embodiments may be realized by providing an additive for a rechargeable lithium battery, the additive being represented by Chemical Formula 1:
*-L3-R3 [Chemical Formula 4]
Chemical Formula 1 may be represented by one of Chemical Formulae 1-1 to 1-4:
X1s may be all hydrogen atoms or all halogen atoms.
Z1 may be a carbon atom.
L1s may be all methylene groups.
L2s may be all ethylene groups.
Z2 may be a nitrogen atom.
L3 may be a single bond; or a combination of a disulfide bond and an ethylene group.
X2s may be all hydrogen atoms or all halogen atoms.
The additive may be one of the following compounds:
The embodiments may be realized by providing an electrolyte layer for a rechargeable lithium battery, the electrolyte layer including the additive according to an embodiment.
The additive may be included in an amount of 0.1 to 10 wt %, based on a total weight of the electrolyte layer.
The electrolyte layer may further include a solid electrolyte.
A weight ratio of solid electrolyte:additive in the electrolyte layer may be 99.9:0.01 to 90:10.
The embodiments may be realized by providing a positive electrode for a rechargeable lithium battery, the positive electrode including the additive according to an embodiment.
The embodiments may be realized by providing a negative electrode for a rechargeable lithium battery, the negative electrode including the additive according to an embodiment.
The embodiments may be realized by providing a rechargeable lithium battery including a positive electrode; a negative electrode; and an electrolyte layer between the positive electrode and the negative electrode, wherein the positive electrode, the negative electrode, or the electrolyte layer includes the additive according to an embodiment.
The rechargeable lithium battery may be an all-solid-state battery, a semi-solid battery, a lithium metal battery, or a lithium ion battery.
Features will be apparent to those of skill in the art by describing in detail exemplary embodiments with reference to the attached drawings in which:
Example embodiments will now be described more fully hereinafter with reference to the accompanying drawings; however, they may be embodied in different forms and should not be construed as limited to the embodiments set forth herein. Rather, these embodiments are provided so that this disclosure will be thorough and complete, and will fully convey exemplary implementations to those skilled in the art.
In addition, it will also be understood that when a layer is referred to as being “between” two layers, it can be the only layer between the two layers, or one or more intervening layers may also be present. Like reference numerals refer to like elements throughout.
The terminology used herein is used to describe embodiments only, and is not intended to limit the embodiments. The singular expression includes the plural expression unless the context clearly dictates otherwise.
As used herein, “combination thereof” means a mixture, a laminate, a composite, a copolymer, an alloy, a blend, a reaction product, and the like of the constituents.
Herein, it should be understood that terms such as “comprises,” “includes,” or “have” are intended to designate the presence of an embodied feature, number, step, element, or a combination thereof, but it does not preclude the possibility of the presence or addition of one or more other features, number, step, element, or a combination thereof.
In the drawings, the thickness of layers, films, panels, regions, etc., may be exaggerated for clarity and like reference numerals designate like elements throughout the specification. It will be understood that when an element such as a layer, film, region, or substrate is referred to as being “on” another element, it can be directly on the other element or intervening elements may also be present. In contrast, when an element is referred to as being “directly on” another element, there are no intervening elements present.
In addition, “layer” herein includes not only a shape formed on the whole surface when viewed from a plan view, but also a shape formed on a partial surface.
In addition, the average particle diameter and average size may be measured by a method well known to those skilled in the art, for example, may be measured by a particle size analyzer, or may be measured by a transmission electron microscopic image or a scanning electron microscopic image. Alternatively, it is possible to obtain an average particle diameter value by measuring a size using a dynamic light scattering method, performing data analysis, counting the number of particles for each particle size range, and calculating from this. Unless otherwise defined, the average particle diameter may mean the diameter (D50) of particles having a cumulative volume of 50 volume % in the particle size distribution.
“Or” is not to be construed as an exclusive meaning, for example, “A or B” is construed to include A, B, A+B, and the like.
As used herein, when specific definition is not otherwise provided, “substituted” refers to replacement of at least one hydrogen of a compound by a substituent of a halogen atom (F, Cl, Br, or I), a hydroxy group, a C1 to C20 alkoxy group, a nitro group, a cyano group, an amine group, an imino group, an azido group, an amidino group, a hydrazino group, a hydrazono group, a carbonyl group, a carbamyl group, a thiol group, an ester group, an ether group, a carboxyl group or a salt thereof, a sulfonic acid group or a salt thereof, a phosphoric acid or a salt thereof, a C1 to C20 alkyl group, a C2 to C20 alkenyl group, a C2 to C20 alkynyl group, a C6 to C30 aryl group, a C3 to C20 cycloalkyl group, a C3 to C20 cycloalkenyl group, a C3 to C20 cycloalkynyl group, a C2 to C20 heterocycloalkyl group, a C2 to C20 heterocycloalkenyl group, a C2 to C20 heterocycloalkynyl group, or a combination thereof.
As used herein, when specific definition is not otherwise provided, “heterocycloalkyl group,” “heterocycloalkenyl group,” “heterocycloalkynyl group” and “heterocycloalkylene group” means that at least one hetero atom of N, O, S, or P is present in the ring compound of cycloalkyl, cycloalkenyl, cycloalkynyl, and cycloalkylene, respectively.
As used herein, when a definition is not otherwise provided, in chemical formula, hydrogen is bonded at the position when a chemical bond is not drawn where supposed to be given.
As used herein, when a definition is not otherwise provided, “*” refers to a linking part or linking point between the same or different atoms, or chemical formulas.
An embodiment may provide an additive for a rechargeable lithium battery represented by Chemical Formula 1.
In Chemical Formula 1, each X1 may independently be, e.g., hydrogen or a halogen atom.
A may be, e.g., a substituent represented by Chemical Formula 2, a substituent represented by Chemical Formula 3, a substituent represented by Chemical Formula 4, a substituent represented by Chemical Formula 5, or a substituted or unsubstituted C1 to C20 alkyl group.
In Chemical Formula 2, Z1 may be, e.g., a carbon atom or a silicon atom.
Each L1 may independently be or include, e.g., a single bond or a substituted or unsubstituted C1 to C20 alkylene group.
Each R1 may independently be or include, e.g., hydrogen, a substituted or unsubstituted C1 to C20 alkyl group, or a substituent represented by Chemical Formula 5.
In Chemical Formula 3, Z2 may be, e.g., a nitrogen atom or a phosphorus atom.
Each L2 may independently be or include, e.g., a single bond or a substituted or unsubstituted C1 to C20 alkylene group.
Each R2 may independently be or include, e.g., a hydrogen atom, a substituted or unsubstituted C1 to C20 alkyl group, or a substituent represented by Chemical Formula 5.
*-L3-R3 [Chemical Formula 4]
L3 may be or may include, e.g., a single bond, a disulfide bond, a substituted or unsubstituted C1 to C20 alkylene group, or a combination thereof.
R3 may be or may include, e.g., a hydrogen atom, a substituted or unsubstituted C1 to C20 alkyl group, or a substituent represented by Chemical Formula 5.
In Chemical Formula 5, each X2 may independently be, e.g., hydrogen or a halogen atom.
The additive of an embodiment may be a compound containing at least one azide group (—N═N═N or —N3) per molecule. The azide group may decompose at a high temperature, e.g., 140° C. or higher, to generate nitrogen (N2), and may be converted to nitrene (—N).
The nitrene group may react with other components of the rechargeable lithium battery to form a film, may drastically reduce ionic conductivity, and may have the effect of shutting down the rechargeable lithium battery at a temperature lower than the ignition temperature.
The additive of an embodiment may help suppress an ignition phenomenon that could otherwise be caused by abnormal heat generation of a rechargeable lithium battery, e.g., when compared to a compound that does not contain an azide group.
The additive of an embodiment may be an additive that can be used regardless of the type of rechargeable lithium battery.
Hereinafter, the additive of an embodiment will be described in detail.
In an implementation, the additive represented by Chemical Formula 1 may be represented by, e.g., one of Chemical Formulas 1-1 to 1-4.
In Chemical Formulae 1-1 to 1-4, Z1 may be, e.g., a carbon atom or a silicon atom.
Z2 may be, e.g., a nitrogen atom or a phosphorus atom.
Each X1 may independently be, e.g., hydrogen or a halogen atom.
Each X2 may independently be, e.g., hydrogen or a halogen atom.
Each L1 may independently be or include, e.g., a single bond or a substituted or
unsubstituted C1 to C20 alkylene group.
Each L2 may independently be or include, e.g., a single bond or a substituted or unsubstituted C1 to C20 alkylene group.
Each L3 may independently be or include, e.g., a single bond, a disulfide bond, a substituted or unsubstituted C1 to C20 alkylene group, or a combination thereof; and
R4 may be or may include, e.g., a hydrogen atom or a substituted or unsubstituted C1 to C20 alkyl group.
In an implementation, Z1 may be a carbon atom.
In an implementation, Z2 may be a nitrogen atom.
In an implementation, X1s may be all hydrogen atoms or all halogen atoms.
In an implementation, X2s may be all hydrogen atoms or all halogen atoms.
In an implementation, L1s may be all methylene groups.
In an implementation, L2s may be all ethylene groups.
In an implementation, L3 may be, e.g., a single bond; or may be a combination of a disulfide bond and an ethylene group.
In an implementation, R4 may be, e.g., a substituted or unsubstituted C1 to C20 alkyl group.
In an implementation, the additive represented by Chemical Formula 1 may be one of the following compounds.
(Electrolyte Layer, Positive Electrode, Negative Electrode, and all-Solid-State Battery)
In another embodiment, an electrolyte layer for a rechargeable lithium battery including the additive according to an embodiment may be provided. In another embodiment, a positive electrode for a rechargeable lithium battery including the additive according to an embodiment may be provided. In another embodiment, a negative electrode for a rechargeable lithium battery including the additive according to an embodiment may be provided.
In another embodiment, a rechargeable lithium battery may include a positive electrode; a negative electrode; and an electrolyte layer between the positive electrode and the negative electrode. In an implementation, at least one of the positive electrode, the negative electrode, and the electrolyte layer may include the additive according to an embodiment.
The rechargeable lithium battery may be, e.g., an all-solid battery, a semi-solid battery, a lithium metal battery, or a lithium ion battery.
In an implementation, the rechargeable lithium battery may be an all-solid-state battery. The all-solid-state battery may also be expressed as an all-solid-state rechargeable battery or an all-solid rechargeable lithium battery.
An all-solid-state battery according to an embodiment may be manufactured by preparing a stack by sequentially stacking a positive electrode, a solid electrolyte, and a negative electrode, and pressurizing or pressing the stack.
The pressurizing may be performed at a temperature of, e.g., 25° C. to 90° C., and may be performed at a pressure of, e.g., less than or equal to 550 MPa, or less than or equal to 500 MPa, for example, 400 MPa to 500 MPa. The pressurizing may be, e.g., isostatic press, roll press, or plate press.
The all-solid-state battery may be a unit cell having a structure of positive electrode/solid electrolyte layer/negative electrode, a bicell having a structure of positive electrode/solid electrolyte layer/negative electrode/solid electrolyte layer/positive electrode, or a stacked battery in which the structures of the unit cell are repeated.
In an implementation, the shape of the all-solid-state battery may be, e.g., coin-shaped, button-shaped, sheet-shaped, stacked-shaped, cylindrical, flat, etc. In an implementation, the all-solid-state battery may also be applied to medium to large-sized batteries used in electric vehicles, etc. In an implementation, the all-solid-state battery may also be used in hybrid vehicles such as plug-in hybrid electric vehicles (PHEV). In an implementation, it may be applied to an energy storage system (ESS) that uses large amounts of power storage, and may also be applied to electric bicycles or power tools.
The solid electrolyte layer includes a solid electrolyte. In this case, the electrolyte layer may be a solid electrolyte layer.
The electrolyte layer may include the additive. Based on a total weight of the electrolyte layer, the additive may be included in an amount of, e.g., 0.1 to 10 wt %, or 0.1 to 5 wt %. In an implementation, a weight ratio of solid electrolyte:additive in the electrolyte layer may be 99.9:0.01 to 90:10, or 99:1 to 90:10. Within these ranges, a shutdown effect by the additive may be properly implemented.
The solid electrolyte may be a type of inorganic solid electrolyte, and may include, e.g., a sulfide solid electrolyte, an oxide solid electrolyte, a halide solid electrolyte, or a combination thereof.
The sulfide solid electrolyte may include, e.g., Li2S—P2S5, Li2S—P2S5—LiX (wherein X is a halogen element, for example I or Cl), Li2S—P2S5—Li2O, Li2S—P2S5—Li2O—LiI, Li2S—SiS2, Li2S—SiS2—LiI, Li2S—SiS2—LiBr, Li2S—SiS2—LiCl, Li2S—SiS2—B2S3—LiI, Li2S—SiS2—P2S5—LiI, Li2S—B2S3, Li2S—P2S5—ZmSn (wherein m and n are an integer, respectively, and Z is Ge, Zn, or Ga), Li2S—GeS2, Li2S—SiS2—Li3PO4, Li2S—SiS2-LipMOq (wherein p and q are integers, and M is P, Si, Ge, B, Al, Ga, or In), or a combination thereof.
The sulfide solid electrolyte may be obtained by, e.g., mixing Li2S and P2S5 in a molar ratio of 50:50 to 90:10 or 50:50 to 80:20 and optionally performing heat-treatment. Within the above mixing ratio ranges, a sulfide solid electrolyte having excellent ionic conductivity may be prepared. The ionic conductivity may be further improved by adding SiS2, GeS2, B2S3, or the like as other components thereto.
Mechanical milling or a solution method may be applied as a mixing method of sulfur-containing raw materials for preparing a sulfide solid electrolyte. The mechanical milling may make starting materials into particulates by putting the starting materials in a ball mill reactor and vigorously stirring them. The solution method may be performed by mixing the starting materials in a solvent to obtain a solid electrolyte as a precipitate. In addition, in the case of heat-treatment after mixing, crystals of the solid electrolyte may be more robust and ionic conductivity may be improved. In an implementation, the sulfide solid electrolyte may be prepared by mixing sulfur-containing raw materials and performing heat treatment two or more times. In an implementation, a sulfide solid electrolyte having high ionic conductivity and robustness may be prepared.
The sulfide solid electrolyte particles according to an embodiment, e.g., may be prepared through a first heat treatment of mixing sulfur-containing raw materials and firing at 120° C. to 350° C. and a second heat treatment of mixing the resultant of the first heat treatment and firing the same at 350° C. to 800° C. The first heat treatment and the second heat treatment may be performed under an inert gas or nitrogen atmosphere, respectively. The first heat treatment may be performed for 1 hour to 10 hours, and the second heat treatment may be performed for 5 hours to 20 hours. Small raw materials may be milled through the first heat treatment, and a final solid electrolyte can be synthesized through the second heat treatment. Through such two or more heat treatments, a sulfide solid electrolyte having high ionic conductivity and high performance can be obtained, and such a solid electrolyte may be suitable for mass production. The temperature of the first heat treatment may be, for example, 150° C. to 330° C., or 200° C. to 300° C., and the temperature of the second heat treatment may be, for example, 380° C. to 700° C., or 400° C. to 600° C.
In an implementation, the sulfide solid electrolyte particles may include argyrodite-type sulfide. The argyrodite-type sulfide solid electrolyte particle may have high ionic conductivity close to the range of 10-4 to 10-2 S/cm, which is the ionic conductivity of some other liquid electrolytes at room temperature, and may form an intimate bond between the positive electrode active material and the solid electrolyte without causing a decrease in ionic conductivity, and furthermore, an intimate interface between the electrode layer and the solid electrolyte layer. An all-solid-state rechargeable battery including the same may have improved battery performance such as rate capability, coulombic efficiency, and cycle-life characteristics.
In an implementation, the argyrodite-type sulfide solid electrolyte particles may include a compound represented by Chemical Formula 21.
(LiaM1bM2c)(PdM3e)(SfM4g)Xh [Chemical Formula 21]
In Chemical Formula 21, 4≤a≤8, M1 may be Mg, Cu, Ag, or a combination thereof, 0≤b<0.5, M2 may be Na, K, or a combination thereof, 0≤c<0.5, M3 may be Sn, Zn, Si, Sb, Ge, or a combination thereof, 0<d<4, 0≤e<1, M4 may be O, SOn, or a combination thereof, 1.5≤n≤5, 3≤f≤12, 0≤g<2, X may be F, Cl, Br, I, or a combination thereof, and 0≤h≤2.
In an implementation, in Chemical Formula 21, a halide element (X) may be necessarily included, and in this case, it may be expressed as 0<h≤2. In an implementation, M1 element may be necessarily included in Chemical Formula 21, and in this case, it may be expressed as 0<b<0.5. In Chemical Formula 21, M3 may be understood as an element substituted for P and may be 0<e<1. In Chemical Formula 21, M4 is substituted for S and, for example, may be 0<g<2, and f, a ratio of S, may be, for example, 3≤f≤7. In an implementation, M4 may be SOn, and SOn may be, e.g., S4O6, S3O6, S2O3, S2O4, S2O5, S2O6, S2O7, S2O8, SO4, or SO5. In an implementation, it may be SO4.
In an implementation, in Chemical Formula 21, a+b+c+h=7, d+e=1, and f+g+h=6.
In an implementation, the argyrodite-type sulfide solid electrolyte particles may include Li3PS4, Li2P3S11, Li2PS6, Li6PS5Cl, Li6PS5Br, Li5.8PS4.8C11.2, Li6.2PS5.2Br0.8, Li5.75PS4.75Cl1.25, (Li5.69Cu0.06)PS4.75Cl1.25, (Li5.72Cu0.03)PS4.75Cl1.25, (Li5.69Cu0.06)P(S4.70(SO4)0.05)Cl1.25, (Li5.69Cu0.06)P(S4.60(SO4)0.15)Cl1.25, (Li5.72Cu0.03)P(S4.725(SO4)0.025)Cl1.25, (Li5.72Na0.03)P(S4.725(SO4)0.025)Cl1.25, Li5.75P(S4.725(SO4)0.025)Cl1.25, or a combination thereof.
The argyrodite-type sulfide solid electrolyte may be prepared, e.g., by mixing lithium sulfide and phosphorus sulfide, and optionally lithium halide. Heat treatment may be performed after mixing them. The heat treatment may include, e.g., two or more heat treatment steps. The method of preparing the argyrodite-type sulfide solid electrolyte may include, e.g., a first heat treatment in which raw materials are mixed and fired at 120° C. to 350° C., and a second heat treatment in which the resultant of the first heat treatment is mixed again and fired at 350° C. to 800° C.
An average particle diameter (D50) of the sulfide-sed solid electrolyte particles may be, e.g., 0.1 μm to 5.0 μm or 0.1 μm to 3.0 μm, and may be small particles of 0.1 μm to 1.9 μm or large particles of 2.0 μm to 5.0 μm. The sulfide solid electrolyte particles may be a mixture of small particles with an average particle diameter of 0.1 μm to 1.9 μm and large particles with an average particle diameter of 2.0 μm to 5.0 μm. The average particle diameter of the sulfide solid electrolyte particles may be measured using an electron microscopic image, e.g., a particle size distribution may be obtained by measuring the size (diameter or long axis length) of about 20 particles in a scanning electron microscopic image, and D50 may be calculated therefrom.
The oxide solid electrolyte may include, e.g., Li1+xTi2-xAl(PO4)3 (LTAP) (0≤x≤4), Li1+x+yAlxTi2-xSiyP3-yO2 (0<x<2, 0≤y<3), BaTiO3, Pb(Zr,Ti)O3 (PZT), Pb1-xLaxZr1-yTiyO3 (PLZT) (0≤x<1, 0≤y<1), PB(Mg3Nb2/3)O3—PbTiO3 (PMN-PT), HfO2, SrTiO3, SnO2, CeO2, Na2O, MgO, NiO, CaO, BaO, ZnO, ZrO2, Y2O3, Al2O3, TiO2, SiO2, lithium phosphate (Li3PO4), lithium titanium phosphate (LixTiy(PO4)3, 0<x<2, 0<y<3), Li1+x+y(Al, Ga)x(Ti, Ge)2-xSiyP3-yO12 (0≤x≤1, 0≤y≤1), lithium lanthanum titanate (LixLayTiO3, 0<x<2, 0<y<3), Li2O, LiAlO2, Li2O—Al2O3—SiO2—P2O5—TiO2—GeO2 ceramics, Garnet ceramics Li3+xLa3M2O12 (wherein M=Te, Nb, or Zr; x is an integer of 1 to 10), or a mixture thereof.
The solid electrolyte layer may further include, e.g., a halide solid electrolyte. The halide solid electrolyte may include a halogen element as a main component, e.g., a ratio of the halide element to all elements constituting the solid electrolyte may be 50 mol % or more, 70 mol % or more, 90 mol % or more, or 100 mol %. In an implementation, the halide solid electrolyte may not include sulfur element.
The halide solid electrolyte may include a lithium element, a metal element other than lithium, and a halogen element. The metal element other than lithium may include Al, As, B, Bi, Ca, Cd, Co, Cr, Fe, Ga, Hf, In, Mg, Mn, Ni, Sb, Sc, Sn, Ta, Ti, Y, Zn, Zr, or a combination thereof. The halogen element may be F, Cl, Br, I, or a combination thereof, e.g., it may be Cl, Br, or a combination thereof. The halide solid electrolyte may be, e.g., represented by LiaM1X6 (M is Al, As, B, Bi, Ca, Cd, Co, Cr, Fe, Ga, Hf, In, Mg, Mn, Ni, Sb, Sc, Sn, Ta, Ti, Y, Zn, Zr, or a combination thereof, X is F, Cl, Br, I, or a combination thereof, and 2≤a≤3). The halide solid electrolyte may include, e.g., Li2ZrCl6, Li2.7Y0.7Zr0.3Cl6, Li2.5Y0.5MZr0.5CO6, Li2.5In0.5Zr0.5CO6, Li2In0.5Zr0.5CO6, Li3YBr6, Li3YCl6, Li3YBr2Cl4, Li3YbCl6, Li2.6Hf0.4Yb0.6Cl6, or a combination thereof.
The solid electrolyte layer may further include a binder. The binder may include, e.g., a nitrile-butadiene rubber, a hydrogenated nitrile-butadiene rubber, a styrene-butadiene rubber, an acrylated styrene-butadiene rubber, an acrylonitrile-butadiene rubber, an acrylic rubber, a butyl rubber, a fluorine rubber, a natural rubber, polydimethylsiloxane, polyethyleneoxide, polyvinylpyrrolidone, polyvinylpyridine, chlorosulfonated polyethylene, polyvinyl alcohol, polytetrafluoroethylene, polyvinylidene fluoride, a polyvinylidene fluoride-hexafluoropropylene copolymer, polyvinylchloride, carboxylated polyvinylchloride, polyvinylfluoride, polyethylene, polypropylene, an ethylene-propylene copolymer, an ethylene-propylene-diene copolymer, polyamideimide, polyimide, poly(meth)acrylate, polyacrylonitrile, polystyrene, polyurethane, a copolymer thereof, or a combination thereof.
The binder may be included in an amount of 0.1 wt % to 3 wt %, for example, 0.5 wt % to 2 wt %, or 0.5 wt % to 1.5 wt %, based on a total weight of the solid electrolyte layer. Maintaining the amount of the binder within the above ranges may help ensure that the components in the solid electrolyte layer may be well combined without reducing the ionic conductivity of the solid electrolyte, thereby improving durability and reliability of the battery.
In an implementation, solid electrolyte layer may further include an alkali metal salt, an ionic liquid, or a conductive polymer.
The alkali metal salt may be, e.g., a lithium salt. A concentration of the lithium salt in the solid electrolyte layer may be greater than or equal to 1 M, e.g., 1 M to 4 M. In an implementation, the lithium salt may improve ionic conductivity by improving lithium ion mobility of the solid electrolyte layer.
The lithium salt may include, e.g., LiPF6, LiBF4, LiSbF6, LiAsF6, LiClO4, LiAlO2, LiAlCl4, LiPO2F2, LiCl, LiI, LiSCN, LiN(CN)2, lithium bis(oxalato)borate (LiBOB), lithium difluoro (oxalato)borate (LiDFOB), lithium difluorobis(oxalato)phosphate (LiDFBP), lithium bis(trifluoromethanesulfonyl)imide (LiTFSI), lithium bis(fluoro)sulfonyl)imide (LiFSI), lithium bis(pentafluoroethanesulfonyl)imide (LiBETI), lithium trifluoromethane sulfonate, lithium tetrafluoroethane sulfonate, or a combination thereof.
In an implementation, the lithium salt may be an imide lithium salt such as LiTFSI, LiFSI, LiBETI, or a combination thereof. The imide lithium salt may help maintain or improve ionic conductivity by appropriately maintaining chemical reactivity with the ionic liquid.
The ionic liquid may have a melting point below room temperature, so it is in a liquid state at room temperature and refers to a salt or room temperature molten salt composed of ions alone.
The ionic liquid may be a compound including a cation, e.g., ammonium, pyrrolidinium, pyridinium, pyrimidinium, imidazolium, piperidinium, pyrazolium, oxazolium, pyridazinium, phosphonium, sulfonium, triazolium, or a mixture thereof, and an anion, e.g., BF4−, PF6−, AsF6−, SbF6−, AlCl4−, HSO4−, ClO4−, CH3SO3−, CF3CO2−, Cl−, Br−, I−, BF4−, SO4−, CF3SO3−, (FSO2)2N−, (C2F5SO2)2N−, (C2FSO2)(CF3SO2)N−, or (CF3SO2)2N−.
The ionic liquid may be, e.g., N-methyl-N-propylpyrrolidinium bis(trifluoromethanesulfonyl)imide, N-butyl-N-methylpyrrolidium bis(3-trifluoromethylsulfonyl)imide, 1-butyl-3-methylimidazolium bis(trifluoromethylsulfonyl)amide, or 1-ethyl-3-methylimidazolium bis(trifluoromethylsulfonyl)amide.
A weight ratio of the solid electrolyte and the ionic liquid in the solid electrolyte layer may be 0.1:99.9 to 90:10, e.g., 10:90 to 90:10, 20:80 to 90:10, 30:70 to 90:10, 40:60 to 90:10, or 50:50 to 90:10. The solid electrolyte layer satisfying the above ranges may maintain or improve ionic conductivity by improving the electrochemical contact area with the electrode. Accordingly, the energy density, discharge capacity, rate capability, etc. of the all-solid-state rechargeable battery may be improved.
In an implementation, the positive electrode may include a current collector and a positive electrode active material layer on the current collector, and the positive electrode active material layer may include a positive electrode active material and may optionally include a solid electrolyte, a binder, and/or a conductive material. In an implementation, the positive electrode active material layer may include the additive.
The positive electrode active material may be a compound (lithiated intercalation compound) capable of intercalating and deintercalating lithium. In an implementation, a composite oxide of lithium and a metal, e.g., cobalt, manganese, nickel, or combinations thereof, may be used.
The composite oxide may be a lithium transition metal composite oxide, e.g., lithium nickel oxide, lithium cobalt oxide, lithium manganese oxide, a lithium iron phosphate compound, cobalt-free nickel-manganese oxide, overlithiated layered oxide, or a combination thereof.
In an implementation, the positive electrode active material may be a high nickel positive electrode active material having a nickel content of greater than or equal to 80 mol % based on 100 mol % of metals excluding lithium in the lithium transition metal composite oxide. The nickel content in the high nickel positive electrode active material may be greater than or equal to 85 mol %, greater than or equal to 90 mol %, greater than or equal to 91 mol %, or greater than or equal to 94 mol %, and less than or equal to 99 mol % based on 100 mol % of metals excluding lithium. The high-nickel positive electrode active materials may achieve high capacity and may be applied to high-capacity, high-density rechargeable lithium batteries.
In an implementation, a compound represented by any of the following chemical formulas may be used. LiaA1-bXbO2-cD′c (0.90≤a≤1.8, 0≤b≤0.5, 0≤c≤0.05); LiaMn2-bXbO4-cD′c (0.90≤a≤1.8, 0≤b≤0.5, 0≤c≤0.05); LiaNi1-b-cCobXcO2-αD′α (0.90≤a≤1.8, 0≤b≤0.5, 0≤c≤0.5, 0<α≤2); LiaNi1-b-cMnbXcO2-αD′α (0.90≤a≤1.8, 0≤b≤0.5, 0≤c≤0.5, 0<α≤2); LiaNibCocL1dGeO2 (0.90≤a≤1.8, 0≤b≤0.9, 0≤c≤0.5, 0≤d≤0.5, 0≤e≤0.1); LiaNiGbO2 (0.90≤a≤1.8, 0.001≤b≤0.1); LiaCoGbO2 (0.90≤a≤1.8, 0.001≤b≤0.1); LiaMn1-bGbO2 (0.90≤a≤1.8, 0.001≤b≤0.1); LiaMn2GbO4 (0.90≤a≤1.8, 0.001≤b≤0.1); LiaMn1-gGgPO4 (0.90≤a≤1.8, 0≤g≤0.5); Li(3-f)Fe2(PO4)3 (0≤f≤2); LiaFePO4 (0.90≤a≤1.8)
In the above chemical formulas, A may be Ni, Co, Mn, or a combination thereof, X may be Al, Ni, Co, Mn, Cr, Fe, Mg, Sr, V, a rare earth element, or a combination thereof, D′ may be O, F, S, P, or a combination thereof, G may be Al, Cr, Mn, Fe, Mg, La, Ce, Sr, V, or a combination thereof, and L1 may be Mn, Al, or a combination thereof.
The positive electrode active material may be a, e.g., lithium nickel oxide represented by Chemical Formula 11, lithium cobalt oxide represented by Chemical Formula 12, a lithium iron phosphate compound represented by Chemical Formula 13, and cobalt-free lithium nickel manganese oxide represented by Chemical Formula 14, or a combination thereof.
Lia1Nix1M1y1M2z1O2-b1Xb1 [Chemical Formula 11]
In Chemical Formula 11, 0.9≤a1≤1.8, 0.3≤x1≤1, 0≤y1≤0.7, 0≤z1≤0.7, 0.9≤x1+y1+z1≤1.1, and 0≤b1≤0.1, M1 and M2 may each independently be Al, B, Ba, Ca, Ce, Co, Cr, Cu, Fe, Mg, Mn, Mo, Nb, Si, Sn, Sr, Ti, V, W, or Zr, and X may be F, P, or S.
In Chemical Formula 1, 0.6≤x1≤1, 0≤y1≤0.4, and 0≤z1≤0.4, or 0.8≤x1≤1, 0≤y1≤0.2, and 0≤z1≤0.2.
Lia2Cox2M3y2O2-b2Xb2 [Chemical Formula 12]
In Chemical Formula 12, 0.9≤a2≤1.8, 0.7≤x2≤1, 0≤y2≤0.3, 0.9≤x2+y2≤1.1, and 0≤b2≤0.1, M3 may be Al, B, Ba, Ca, Ce, Cr, Cu, Fe, Mg, Mn, Mo, Ni, Se, Si, Sn, Sr, Ti, V, W, Y, Zn, or Zr, and X may be F, P, or S.
Lia3Fex3M4y3PO4-b3Xb3 [Chemical Formula 13]
In Chemical Formula 13, 0.9≤a3<1.8, 0.6<x3<1, 0≤y3<0.4, and 0≤b3<0.1, M4 may be Al, B, Ba, Ca, Ce, Co, Cr, Cu, Mg, Mn, Mo, Ni, Se, Si, Sn, Sr, Ti, V, W, Y, Zn, or Zr, and X may be F, P, or S.
Lia4Nix4Mny4M5z4O2-b4Xb4 [Chemical Formula 14]
In Chemical Formula 14, 0.9≤a2≤1.8, 0.8≤x4<1, 0<y4≤0.2, 0≤z4≤0.2, 0.9≤x4+y4+z4≤1.1, and 0≤b4≤0.1, M5 may be Al, B, Ba, Ca, Ce, Cr, Fe, Mg, Mo, Nb, Si, Sn, Sr, Ti, V, W, or Zr, and X may be F, P, or S.
An average particle diameter (D50) of the positive electrode active material may be 1 μm to 25 μm, e.g. 3 μm to 25 μm, 1 μm to 20 μm, 1 μm to 18 μm, 3 μm to 15 μm, or 5 μm to 15 μm. In an implementation, the positive electrode active material may include small particles having an average particle diameter (D50) of 1 μm to 9 μm and large particles having an average particle diameter (D50) of 10 μm to 25 μm. A positive electrode active material having this particle size range may be harmoniously mixed with other components within the positive electrode active material layer and may achieve high capacity and high energy density. In an implementation, the average particle diameter may be obtained by selecting about 20 particles at random among particles in a scanning electron microscopic image of the positive electrode active material, measuring the particle diameter (diameter, long axis, or length of the long axis) to obtain the particle size distribution, and taking the diameter (D50) of particles with a cumulative volume of 50 volume % as the average particle diameter in the particle size distribution.
The positive electrode active material may be in the form of secondary particles made by agglomerating a plurality of primary particles, or may be in the form of single particles. In an implementation, the positive electrode active material may have a spherical or close to spherical shape, or may have a polyhedral or irregular shape.
In an implementation, the positive electrode active material may include a buffer layer on the particle surface. The buffer layer can be expressed as a coating layer, a protective layer, etc., and can play a role in lowering the interfacial resistance between the positive electrode active material and the sulfide solid electrolyte particles. In an implementation, the buffer layer may include lithium-metal-oxide, where the metal may be, e.g., Al, B, Ca, Ce, Cr, Fe, Mg, Mo, Nb, Si, Sn, Sr, Ta, V, W, or Zr. The lithium-metal-oxide may improve the performance of the positive electrode active material by facilitating the movement of lithium ions and electronic conduction, while lowering the interfacial resistance between the positive electrode active material and solid electrolyte particles.
The positive electrode active material may be included in an amount of 55 wt % to 99.5 wt %, e.g., 65 wt % to 95 wt %, or 75 wt % to 91 wt %, based on a total weight of the positive electrode active material layer.
The binder may serve to attach the positive electrode active material particles well to each other and also to attach the positive electrode active material well to the current collector. Examples of the binder may include polyvinyl alcohol, carboxymethyl cellulose, hydroxypropyl cellulose, diacetyl cellulose, polyvinylchloride, carboxylated polyvinylchloride, polyvinylfluoride, a polymer including ethylene oxide, polyvinylpyrrolidone, polyurethane, polytetrafluoroethylene, polyvinylidene fluoride, polyethylene, polypropylene, a styrene-butadiene rubber, a (meth)acrylated styrene-butadiene rubber, an epoxy resin, a (meth)acrylic resin, a polyester resin, nylon, and the like.
The conductive material may be used to impart conductivity to the electrode. A suitable material that does not cause chemical change and conducts electrons can be used in the battery. Examples of the conductive material may include a carbon material such as natural graphite, artificial graphite, carbon black, acetylene black, ketjen black, a carbon fiber, a carbon nanofiber, and carbon nanotube; a metal material containing copper, nickel, aluminum, silver, etc., in a form of a metal powder or a metal fiber; a conductive polymer such as a polyphenylene derivative; or a mixture thereof.
A content of the binder and the conductive material may be 0.5 wt % to 5 wt %, respectively, based on a total weight of the positive electrode active material layer.
In an implementation, positive electrode active material layer may further include a solid electrolyte. The solid electrolyte may include, e.g., a sulfide solid electrolyte, an oxide solid electrolyte, a halide solid electrolyte, or a combination thereof.
Based on a total weight of the positive electrode active material layer, the solid electrolyte may be included in an amount of 0.1 wt % to 35 wt %, e.g., 1 wt % to 35 wt %, 5 wt % to 30 wt %, and 8 wt % to 25 wt %, or 10 wt % to 20 wt %.
In the positive electrode active material layer, based on a total weight of the positive electrode active material and solid electrolyte, 65 wt % to 99 wt % of the positive electrode active material and 1 wt % to 35 wt % of the solid electrolyte may be included, and for example, 80 wt % to 90 wt % of the positive electrode active material and 10 wt % to 20 wt % of solid electrolyte may be included. Maintaining the amount of the solid electrolyte at these amounts may help ensure that the efficiency and cycle-life characteristics of the all-solid-state rechargeable battery can be improved without reducing the capacity.
The current collector may include Al.
In an implementation, a negative electrode for an all-solid-state battery may include a current collector and a negative electrode active material layer on the current collector. The negative electrode active material layer may include a negative electrode active material and may further include a binder, a conductive material, or a solid electrolyte. In an implementation, the negative electrode active material layer may include the additive.
The negative electrode active material may be a material that reversibly intercalates/deintercalates lithium ions, a lithium metal, a lithium metal alloy, a material capable of doping and dedoping lithium, or a transition metal oxide.
The material that reversibly intercalates/deintercalates lithium ions may include a carbon negative electrode active material, e.g., crystalline carbon, amorphous carbon or a combination thereof. The crystalline carbon may be graphite such as non-shaped, sheet-shaped, flake-shaped, sphere-shaped, or fiber-shaped natural graphite or artificial graphite. The amorphous carbon may be a soft carbon, a hard carbon, a mesophase pitch carbonization product, calcined coke, or the like.
The lithium metal alloy may include lithium and, e.g., Na, K, Rb, Cs, Fr, Be, Mg, Ca, Sr, Si, Sb, Pb, In, Zn, Ba, Ra, Ge, Al, or Sn.
The material capable of doping/dedoping lithium may be a Si negative electrode active material or a Sn negative electrode active material, the Si negative electrode active material may include silicon, a silicon-carbon composite, SiOx (0<x<2), a Si-Q alloy (wherein Q is an element selected from an alkali metal, an alkaline-earth metal, a Group 13 element, a Group 14 element, a Group 15 element, a Group 16 element, a transition metal, a rare earth element, and a combination thereof, but not Si), and the Sn negative electrode active material may include Sn, SnO2, a Sn—R alloy (wherein R is an element selected from an alkali metal, an alkaline-earth metal, a Group 13 element, a Group 14 element, a Group 15 element, a Group 16 element, a transition metal, a rare earth element, and a combination thereof, but not Sn), and at least one of these may be mixed with SiO2. The elements Q and R may be Mg, Ca, Sr, Ba, Ra, Sc, Y, Ti, Zr, Hf, Rf, V, Nb, Ta, Db, Cr, Mo, W, Sg, Tc, Re, Bh, Fe, Pb, Ru, Os, Hs, Rh, Ir, Pd, Pt, Cu, Ag, Au, Zn, Cd, B, Al, Ga, Sn, In, Tl, Ge, P, As, Sb, Bi, S, Se, Te, Po, or a combination thereof.
In an implementation, the silicon-carbon composite may be a silicon-carbon composite including a core including crystalline carbon and silicon particles and an amorphous carbon coating layer on the surface of the core. The crystalline carbon may be artificial graphite, natural graphite, or a combination thereof. The amorphous carbon precursor may be coal pitch, mesophase pitch, petroleum pitch, coal oil, petroleum heavy oil, or a polymer resin such as phenol resin, furan resin, and polyimide resin. In an implementation, a content of silicon may be 10 wt % to 50 wt % based on a total weight of the silicon-carbon composite. In an implementation, a content of the crystalline carbon may be 10 wt % to 70 wt % based on a total weight of the silicon-carbon composite, and a content of the amorphous carbon may be 20 wt % to 40 wt % based on a total weight of the silicon-carbon composite. In an implementation, a thickness of the amorphous carbon coating layer may be 5 nm to 100 nm.
An average particle diameter (D50) of the silicon particles may be 10 nm to 20 m, e.g., 10 nm to 200 nm. The silicon particles may exist in an oxidized form, and in this case, the atomic content ratio of Si:O in the silicon particles, which indicates a degree of oxidation, may be 99:1 to 33:67. The silicon particles may be SiOx particles, and in this case, the x range in SiOx may be greater than 0 and less than 2.
The Si negative electrode active material or the Sn negative electrode active material may be used in combination with a carbon negative electrode active material. A mixing ratio of the Si negative electrode active material or Sn negative electrode active material; and a carbon negative electrode active material; may be 1:99 to 90:10.
In the negative electrode active material layer, the negative electrode active material may be included in an amount of 95 wt % to 99 wt % based on a total weight of the negative electrode active material layer.
In an implementation, the negative electrode active material layer further includes a binder, and may optionally further include a conductive material. The content of the binder in the negative electrode active material layer may be 1 wt % to 5 wt % based on a total weight of the negative electrode active material layer. In an implementation, the conductive material may be further included, and the negative electrode active material layer may include 90 wt % to 98 wt % of the negative electrode active material, 1 wt % to 5 wt % of the binder, and 1 wt % to 5 wt % of the conductive material.
The binder may serve to attach the negative electrode active material particles well to each other and also to attach the negative electrode active material well to the current collector. The binder may be a water-insoluble binder, a water-soluble binder, or a combination thereof.
The water-insoluble binder may be, e.g., polyvinyl chloride, carboxylated polyvinyl chloride, polyvinyl fluoride, an ethylene oxide-containing polymer, an ethylene propylene copolymer, polystyrene, polyvinylpyrrolidone, polyurethane, polytetrafluoro ethylene, polyvinylidene fluoride, polyethylene, polypropylene, polyamideimide, polyimide, or a combination thereof.
The water-soluble binder may include a rubber binder or a polymer resin binder. The rubber binder may include a styrene-butadiene rubber, an acrylated styrene-butadiene rubber, an acrylonitrile-butadiene rubber, an acrylic rubber, a butyl rubber, a fluororubber, or a combination thereof. The polymer resin binder may include polyethylene oxide, polyvinylpyrrolidone, polyepichlorohydrin, polyphosphazene, polyacrylonitrile, an ethylene propylene diene copolymer, polyvinylpyridine, chlorosulfonated polyethylene, latex, a polyester resin, an acrylic resin, a phenol resin, an epoxy resin, polyvinyl alcohol, or a combination thereof.
In an implementation, a water-soluble binder may be used as the negative electrode binder, and a cellulose compound viscosity capable of imparting viscosity may be used. The cellulose compound may include carboxymethyl cellulose, hydroxypropylmethyl cellulose, methyl cellulose, an alkali metal salt thereof, or a mixture thereof. The alkali metal may be Na, K, or Li. An amount of such a thickener used may be 0.1 parts by weight to 3 parts by weight based on 100 parts by weight of the negative electrode active material.
The conductive material may be used to provide conductivity to the electrode, and a suitable material that has electronic conductivity without causing chemical change can be used. The conductive material may include, e.g., a carbon material such as natural graphite, artificial graphite, carbon black, acetylene black, ketjen black, a carbon fiber, a carbon nanofiber, carbon nanotube, or the like; a metal material of a metal powder or a metal fiber including copper, nickel, aluminum silver, or the like; a conductive polymer such as a polyphenylene derivative; or a mixture thereof.
The negative electrode current collector may include, e.g., a copper foil, a nickel foil, a stainless steel foil, a titanium foil, a nickel foam, a copper foam, a polymer substrate coated with a conductive metal, or a combination thereof.
In an implementation, the negative electrode for the all-solid-state battery may be a precipitation-type negative electrode. The precipitation-type negative electrode may be a negative electrode which has no negative electrode active material during the assembly of a battery but in which a lithium metal and the like are precipitated during the charge of the battery and serve as a negative electrode active material.
The negative electrode coating layer 405 may include metal or a carbon material which plays a role of a catalyst.
The metal may include, e.g., gold, platinum, palladium, silicon silver, aluminum, bismuth, tin, zinc, or a combination thereof, and may be composed of one selected therefrom or an alloy of more than one. An average particle diameter (D50) of the metal may be less than or equal to 4 μm, e.g., 10 nm to 4 μm, 10 nm to 2 μm, or 10 nm to 1 μm.
The carbon material may be, e.g., crystalline carbon, non-graphitic carbon, or a combination thereof. In an implementation, the crystalline carbon may be natural graphite, artificial graphite, mesophase carbon microbeads, or a combination thereof. The non-graphitic carbon may be carbon black, activated carbon, acetylene black, denka black, ketjen black, furnace black, graphene, or a combination thereof.
In an implementation, the negative electrode coating layer 405 may include both the metal and the carbon material, and a mixing ratio of the metal and the carbon material may be, e.g., a weight ratio of 1:10 to 1:2, 1:10 to 2:1, 5:1 to 1:1, or 4:1 to 2:1. In this case, the precipitation of lithium metal may be effectively promoted and the characteristics of the all-solid-state battery can be improved. In an implementation, the negative electrode coating layer 405 may include a carbon material on which a catalyst metal is supported, or may include a mixture of metal particles and carbon material particles.
The negative electrode coating layer 405 may further include a binder, and the binder may be, e.g., a conductive binder. In an implementation, the negative electrode coating layer 405 may further include an additive, e.g., fillers, dispersants, and ion conductive materials.
A thickness of the negative electrode coating layer 405 may be, e.g., 1 μm to 20 μm, 2 μm to 10 μm, or 3 μm to 7 μm. In an implementation, the thickness of the negative electrode coating layer 405 may be less than or equal to 50%, less than or equal to 20%, or less than or equal to 5% of the thickness of the positive electrode active material layer. If the thickness of the negative electrode coating layer 405 were to be too thin, it could be collapsed by the lithium metal layer 404, and if the thickness were to be too thick, the density of the all-solid-state battery could decrease and internal resistance may increase.
The precipitation-type negative electrode 400′ may further include a thin film, e.g., on the surface of the current collector, e.g., between the current collector and the negative electrode catalyst layer. The thin film may include an element capable of forming an alloy with lithium. The element capable of forming an alloy with lithium may be, e.g., gold, silver, zinc, tin, indium, silicon, aluminum, bismuth, or the like, which may be used alone or an alloy of more than one. The thin film may further help planarize a precipitation shape of the lithium metal layer 404 and much improve characteristics of the all-solid-state rechargeable battery. The thin film may be formed, e.g., in a vacuum deposition method, a sputtering method, a plating method, or the like. The thin film may have, e.g., a thickness of 1 nm to 800 nm, or 100 nm to 500 nm.
The lithium metal layer 404 may include a lithium metal or a lithium alloy. The lithium alloy may be, e.g., a Li—Al alloy, a Li—Sn alloy, a Li—In alloy, a Li—Ag alloy, a Li—Au alloy, a Li—Zn alloy, a Li—Ge alloy, or a Li—Si alloy.
A thickness of the lithium metal layer 404 may be 1 μm to 500 μm, 1 μm to 200 μm, 1 μm to 100 μm, or 1 μm to 50 μm. If the thickness of the lithium metal layer 404 were to be too thin, it could be difficult to perform the role of a lithium storage, and if were to be is too thick, the battery volume could increase and performance could deteriorate.
When applying such a precipitation-type negative electrode, the negative electrode coating layer 405 may serve to protect the lithium metal layer 404 and suppress the precipitation growth of lithium dendrite. In an implementation, short circuit and capacity degradation of the all-solid-state battery may be suppressed and cycle-life characteristics may be improved.
The following Examples and Comparative Examples are provided in order to highlight characteristics of one or more embodiments, but it will be understood that the Examples and Comparative Examples are not to be construed as limiting the scope of the embodiments, nor are the Comparative Examples to be construed as being outside the scope of the embodiments. Further, it will be understood that the embodiments are not limited to the particular details described in the Examples and Comparative Examples.
Compound D (a compound represented by Chemical Formula 1-1a) was obtained in the method under the following condition 1 or 2.
In a 250 mL round-bottomed flask, trimethyloipropane (Compound A) (1.3 g, 9.7 mmol) and pentafluorobenzoic acid (Compound B) (10 g, 29 mmol) were mixed and dissolved in 50 mL of dichoromethane (CH2Cl2). Subsequently, dicyclohexylcarbodiimide (DCC) (6.0 g, 29 mmol) and 4-dimethylaminopyridinium-paratoluenesulfonate salt (DMAP-TsOH) (0.44 g, 1.5 mmol) were added thereto. The reaction mixture was stirred at ambient temperature for 24 hours. After checking if a reaction has progressed through TLC, 1 mL of water was added thereto and then, stirred for 10 minutes, and an N,N′-dicyclohexylurea by-product was removed from the reaction mixture by filtration with a filter paper. After adding 100 mL of water to a filtrate therefrom, the mixture was extracted three times with dichloromethane (150 mL×3 times). The extracted organic layer was collected, washed with salt-saturated water (brine), and dried with anhydrous magnesium sulfate, and a filtrate therefrom was concentrated by using a vacuum rotary evaporator to obtain a white solid. This was recrystallized by using dichloromethane and hexane to obtain Compound C as a white solid at a yield of 70%.
To a 250 mL brown round-bottomed flask, Compound C (2.5 g, 3.5 mmol) and sodium azide (0.91 g, 14 mmol) were added. Subsequently, 30 mL of acetone was added in a dropwise fashion thereto to dissolve Compound C, and 15 mL of distilled water was added in a dropwise fashion thereto to dissolve the sodium azide. The reaction mixture was stirred overnight at 50° C. by installing a reflux cooler. After cooling the reaction mixture to ambient temperature, acetone was removed therefrom by using a rotary evaporator. Subsequently, water (20 mL) and dichloromethane (50 mL) were added to the reaction mixture, and an aqueous layer was extracted three times with dichloromethane (50 mL×3 times). The extracted organic layer was washed with salt-saturated water, dried anhydrous magnesium sulfate, and filtered, and a filtrate therefrom was concentrated with a vacuum rotary evaporator. The concentrated product was recrystallized by using dichloromethane and hexane to obtain desired Compound D (a compound represented by Chemical Formula 1-1a) as a white solid at a yield of 77%.
In a 250 mL round-bottomed flask, trimethylolpropane (Compound A) (1.9 g, 14 mmol) and pentafluorobenzoic acid (Compound B) (17 g, 49 mmol) were mixed and then, dissolved in 150 mL of toluene. Subsequently, a hafnium catalyst (HfCl4 (THF)2), 0.23 g, 0.49 mmol) was added thereto. The reaction mixture was stirred for 2 days under heated reflux conditions by installing a Dean-stark trap and a reflux cooler. A reaction proceeded, while removing an azeotropic mixture of toluene and water generated during the reaction. After cooling the reaction mixture to ambient temperature, a NaHCO3 solution was added to a filtrate therefrom until it appeared basic and then, extracted three times with dichloromethane (150 mL×3 times). The extracted organic layer was washed with salt-saturated water (brine) and dried with anhydrous magnesium sulfate, and a filtrate therefrom was concentrated with a vacuum rotary evaporator. Subsequently, the concentrated product was purified through column chromatography (hexanes:EtOAc=4:1, Rf=0.63) to obtain Compound D (a compound represented by Chemical Formula 1-1a) as a white solid at a yield of 66%. A product therefrom may be purified through column chromatography or by recrystallization in CH2Cl2/hexanes.
1H NMR (CDCl3, 400 MHz): δ 4.40 (s, 6H), 1.67 (q, J=7.4 Hz, 2H), 0.99 (t, J=7.4 Hz, 3H); 19F NMR (CDCl3, 376 MHz): δ −138.24 (m, 6F), −150.5 (m, 6F); LRMS(ESI, positive mode): m/z calculated for [M+Na+]808.0533, found 808.1667.
In a 250 ml round-bottomed flask, trimethylolpropane (Compound A) (0.44 g, 3.3 mmol) and 4-azidobenzoic acid (Compound E) (1.78 g, 10.9 mmol) were mixed and dissolved in 50 mL of dichloromethane (CH2Cl2). Subsequently, N,N′-dicyclohexylcarbodiimide (DCC) (2.25 g, 10.9 mmol) and 4-dimethylaminopyridinium-paratoluenesulfonate salt (DMAP-TsOH) (0.16 g, 5 mol %) were added thereto. The reaction mixture was stirred at ambient temperature for 24 hours. After checking if a reaction was all progressed through TLC, 1 mL of water was added thereto and then, stirred for 10 minutes, and a N,N′-dicyclohexylurea by-product was removed by filtration with a filter paper. After adding 30 mL of water to the filtrate, the mixture was extracted three times with dichloromethane (30 mL×3 times). The extracted organic layer was gathered, washed with salt-saturated water (brine), dried with anhydrous magnesium sulfate, and filtered, and a filtrate therefrom was concentrated with a vacuum rotary evaporator to obtain a white solid. This was purified through column chromatography (hexanes:EtOAc=4:1, Rf=0.49) to obtain desired compound F (a compound represented by Chemical Formula 1-1b) as yellow oil at a yield of 73%.
1H NMR (CDCl3, 400 MHz): δ 7.98 (d, J=8.8 Hz, 6H), δ 7.03 (d, J=8.8 Hz, 6H), δ 4.47 (s, 6H), δ 1.76 (q, J=7.6 Hz, 2H), δ 1.06 (t, J=7.6 Hz, 3H)
In a 100 mL round-bottomed flask, triethanolamine (Compound G) (0.25 g, 1.66 mmol) and pentafluorobenzoic acid (Compound B) (1.06 g, 4.99 mmol) were mixed and dissolved in 30 mL of dichloromethane (CH2Cl2). Subsequently, N,N′-dicyclohexylcarbodiimide (DCC) (1.03 g, 4.99 mmol) and 4-dimethylaminopyridinium-paratoluenesulfonate salt (DMAP-TsOH) (73 mg, 5 mol %) were added thereto. The reaction mixture was stirred at ambient temperature for 24 hours. After checking if a reaction had progressed through TLC, 1 mL of water was added thereto and then, stirred for 10 minutes, and an N,N′-dicyclohexylurea by-product was removed therefrom by filtration with a filter paper. Subsequently, 100 mL of water was added to a filtrate therefrom and then, extracted three times with dichloromethane (30 mL×3 times). The extracted organic layer was washed with salt-saturated water (brine), dried with anhydrous magnesium sulfate, and filtered, and a filtrate therefrom was concentrated by using a vacuum rotary evaporator to obtain Compound H as a white solid at a yield of 77%. The product was judged to be superior to impurities through 1H NMR, the next step proceeded without purification.
1H NMR (CDCl3, 400 MHz): δ 4.44 (t, J=5.4 Hz, 6H), δ 3.03 (t, J=5.2 Hz, 6H); 19F NMR (CDCl3, 376 MHz): δ −138.32 (d, J=20 Hz, 6H), δ −148.099 (d, J=22 Hz, 3H), δ −160.27 (d, J=15.6 Hz, 6H).
To a 100 mL round-bottomed flask, Compound H (1.21 g, 1.66 mmol) and sodium azide (0.38 g, 5.8 mmol, 3.5 eq) were added. After adding 20 mL of acetone in a dropwise fashion thereto to dissolve Compound H, 10 mL of distilled water was added thereto in a dropwise fashion to dissolve the sodium azide. The mixture was stirred at 50° C. for 24 hours by placing a stirring magnet in the flask and installing a reflux cooler thereto. Subsequently, the flask containing the mixture was cooled to ambient temperature, and the acetone was removed therefrom by using a rotary evaporator. After adding dichloromethane (30 mL) and water (10 mL) to the reaction mixture, an aqueous layer was extracted three times with dichloromethane (30 mL×3 times). The extracted organic layer was gathered again and washed with salt-saturated water (brine). Subsequently, a product therefrom was dried with anhydrous magnesium sulfate and filtered to remove anhydrous magnesium sulfate therefrom. A filtrate therefrom was concentrated through a vacuum rotary evaporator to obtain a white solid. A product therefrom was purified through column chromatography (hexanes:EtOAc=4:1, Rf:0.38) to obtain desired Compound I (a compound represented by Chemical Formula 1-2a) as a white solid at a yield of 61%.
1H NMR (400 MHz, CDCl3): δ 4.43 (t, J=5.6 Hz, 6H), δ 3.03 (t, J=5.6 Hz, 6H); 19F NMR (375 MHz, CDCl3): δ −138.76 (d, J=9.6 Hz, 6H), δ −150.95 (d, J=9.6 Hz, 6H)
In a 100 mL brown round-bottomed flask, 4-azido-2,3,5,6-tetrafluorobenzoic acid (Compound J) (0.9 g, 3.8 mmol) and bis(2-hydroxyethyl)disulfide (Compound K) (0.30 g, 1.9 mmol) were mixed and dissolved in 10 mL of dichloromethane (CH2Cl2). Subsequently, dicyclohexylcarbodiimide (DCC) (0.79 g, 3.8 mmol) and dimethylaminopyridinium-paratoluenesulfonate salt (DMAP TsOH) (56 mg, 0.19 mmol) were added thereto. The reaction mixture was stirred at ambient temperature for 48 hours. After checking if a reaction had progressed through TLC, 0.1 mL of water was added thereto and then, stirred for 10 minutes, and a N,N′-dicyclohexylurea by-product was removed from the reaction mixture by filtration with a filter paper. After adding 10 mL of water to a filtrate therefrom, the mixture was extracted three times with dichloromethane (15 mL×3 times). The extracted organic layer was washed with salt-saturated water, dried with anhydrous magnesium sulfate, and filtered, and a filtrate therefrom was concentrated with a vacuum rotary evaporator. Subsequently, the concentrated product was purified through column chromatography (hexanes:EtOAc=4:1, Rf=0.55) to obtain Compound L (a compound represented by Chemical Formula 1-3a) as a white solid at a yield of 73%.
1H NMR (CDCl3, 400 MHz): δ 4.63 (t, J=6.6 Hz, 4H), 3.66 (t, J=6.6 Hz, 4H); 19F NMR (CDCl3, 376 MHz): δ −138.24 (m, 6F), −150.77 (m, 6F).
In a 100 mL brown round-bottomed flask, 4-azido-2,3,5,6-tetrafluorobenzoic acid (Compound J) (0.80 g, 3.4 mmol) and n-octanol (Compound M) (0.44 g, 3.4 mmol) were mixed and dissolved in 5 mL of dichloromethane (CH2Cl2). Subsequently, dicyclohexylcarbodiimide (DCC) (0.70 g, 3.4 mmol) and 4-dimethylaminopyridinium-paratoluenesulfonate salt (DMAP TsOH) (21 mg, 0.17 mmol) were added thereto. The reaction mixture was stirred at ambient temperature for 48 hours. After checking if a reaction had progressed through TLC, 0.1 mL of water was added thereto and then, stirred for 10 minutes, and a N,N′-dicyclohexylurea by-product was removed from the reaction mixture by filtration with a filter paper. After adding 10 mL of water to a filtrate therefrom, the mixture was extracted three times with dichloromethane (15 mL x 3 times). The extracted organic layer was washed with salt-saturated water, dried with anhydrous magnesium sulfate, and filtered, and a filtrate therefrom was concentrated with a vacuum rotary evaporator. Subsequently, the concentrated product was purified through column chromatography (hexanes:EtOAc=10:1, Rf=0.55) to obtain Compound N (a compound represented by Chemical Formula 1-4a) as a white solid at a yield of 78%.
1H NMR (CDCl3, 400 MHz): δ 4.36 (t, J=6.6 Hz, 2H), 1.74 (t, J=7.6 Hz, 2H), 1.34 (m, 10H), 0.88 (t, J=5.9 Hz, 2H). 19F NMR (CDCl3, 376 MHz): δ −138.84 (m, 6F), −150.97 (m, 6F).
In a 250 mL round-bottomed flask, trimethylolpropane (Compound A) (1.3 g, 9.7 mmol) and pentafluorobenzoic acid (Compound B) (10 g, 29 mmol) were mixed and dissolved in 50 mL of dichloromethane (CH2Cl2). Subsequently, dicyclohexylcarbodiimide (DCC) (6.0 g, 29 mmol) and dimethylaminopyridinium-paratoluenesulfonate salt (DMAP TsOH) (0.44 g, 1.5 mmol) were added thereto. The reaction mixture was stirred at ambient temperature for 24 hours. After checking if a reaction had progressed through TLC, 1 mL of water was added thereto and then, stirred for 10 minutes, and a N,N′-dicyclohexylurea by-product was removed from the reaction mixture by filtration with a filter paper. After adding 10 mL of water to a filtrate therefrom, the mixture was extracted three times with dichloromethane (15 mL×3 times). The extracted organic layer was washed with salt-saturated water, dried with anhydrous magnesium sulfate, and filtered, and a filtrate therefrom was concentrated with a vacuum rotary evaporator to obtain a white solid. This was recrystallized with dichloromethane and hexane to obtain Compound C (a compound represented by Chemical Formula 1-1c) as a white solid at a yield of 70%.
An acryl binder (SX-A334, Zeon Corp.) was dissolved in an isobutyryl isobutyrate (octyl acetate, OA) solvent to prepare a binder solution, and an argyrodite-type solid electrolyte Li6PS5Cl (D50=3 m) and the additive of Synthesis Example 1 (a compound represented by Chemical Formula 1-1a) in a weight ratio of 95:5 were added thereto and then, stirred in a Thinky mixer to secure appropriate viscosity. After adjusting the viscosity, 2 mm zirconia balls were added thereto and then, stirred again with the Thinky mixer to prepare slurry. The slurry included 93.1 wt % of the solid electrolyte, 4.9 wt % of the additive of Synthesis Example 1, and 2 wt % of the binder. The slurry was applied on a release PET film with a bar coater and dried at ambient temperature to form a solid electrolyte layer.
85 wt % of a positive electrode active material, LiNi0.9Co0.05Mn0.05O2, 13.5 wt % of a lithium argyrodite-type solid electrolyte, Li6PS5C1, 1.0 wt % of a polyvinylidene fluoride binder, and 0.5 wt % of a carbon nanotube conductive material were prepared and then, added to a dispersion medium prepared by mixing octyl acetate (OA) and pentyl propionate (PPP) in a weight ratio of 1:1. The obtained mixture was added to a Thinky mixer, and 2 mm zirconia balls were added thereto and then, stirred to prepare a positive electrode composition. A content of the dispersion medium was 30 parts by weight based on 100 parts by weight of a solid content. The solid content was a total of the positive electrode active material, the solid electrolyte, the binder, and the conductive material.
The prepared positive electrode composition was coated on a positive electrode current collector with a bar coater and dried at 80° C. for 10 minutes in a convention oven to form a positive electrode active material layer thereon, manufacturing a positive electrode having positive electrode active material layer on the current collector.
After preparing a catalyst by mixing carbon black (having a primary particle diameter (D50) of about 30 nm) and silver (Ag) (having an average particle diameter (D50) of about 60 nm) in a weight ratio of 3:1, 0.25 g of the catalyst was added to 2 g of an NMP solution including 7 wt % of a polyvinylidene fluoride binder and then, mixed, preparing a negative electrode coating layer composition. This was coated on a nickel foil current collector using a bar coater and dried under vacuum to prepare a precipitated negative electrode with a negative electrode coating layer formed on the current collector.
(4) Manufacture of all-Solid-State Battery Cell
After cutting the positive electrode, negative electrode, and solid electrolyte layer, the solid electrolyte layer was stacked on the positive electrode, and the negative electrode was stacked thereon. This was sealed in the form of a pouch and then, subjected to warm Isostatic press (WIP) at a temperature of 85° C. under 500 MPa for 30 minutes to manufacture an all-solid-state battery cell. In this pressurized state, the positive electrode active material layer had a thickness of about 100 μm, the negative electrode coating layer had a thickness of about 7 μm, and the solid electrolyte layer had a thickness of about 60 km.
A solid electrolyte layer and an all-solid-state battery cell were manufactured in the same method as in Example 1, except that the additive of Synthesis Example 2 (a compound represented by Chemical Formula 1-1b) was used instead of the additive of Synthesis Example 1 (a compound represented by Chemical Formula 1-1a).
A solid electrolyte layer and an all-solid-state battery cell were manufactured in the same method as in Example 1, except that the additive of Synthesis Example 3 (a compound represented by Chemical Formula 1-2a) was used instead of the additive of Synthesis Example 1 (a compound represented by Chemical Formula 1-1a).
A solid electrolyte layer and an all-solid-state battery cell were manufactured in the same method as in Example 1, except that the additive of Synthesis Example 4 (a compound represented by Chemical Formula 1-3a) was used instead of the additive of Synthesis Example 1 (a compound represented by Chemical Formula 1-1a).
A solid electrolyte layer and an all-solid-state battery cell were manufactured in the same method as in Example 1, except that the additive of Synthesis Example 5 (a compound represented by Chemical Formula 1-4a) was used instead of the additive of Synthesis Example 1 (a compound represented by Chemical Formula 1-1a).
A solid electrolyte layer was formed by using the argyrodite-type solid electrolyte Li6PS5Cl (D50=3 m) and the additive of Synthesis Example 1 in a weight ratio of 97:3 to prepare slurry including 95.06 wt % of the solid electrolyte, 2.94 wt % of the additive of Synthesis Example 1, and 2 wt % of the binder. An all-solid-state battery cell was manufactured in the same manner as in Example 1 except for this.
A solid electrolyte layer was formed by using the argyrodite-type solid electrolyte Li6PS5Cl (D50=3 m) and the additive of Synthesis Example 1 in a weight ratio of 90:10 to prepare slurry including 88.2 wt % of the solid electrolyte, 9.8 wt % of the additive of Synthesis Example 1, and 2 wt % of the binder. An all-solid-state battery cell was manufactured in the same manner as in Example 1 except for this.
A solid electrolyte layer was formed by adding the argyrodite-type solid electrolyte Li6PS5Cl (D50=3 m) alone to prepare slurry including 98 wt % of the solid electrolyte and 2 wt % of the binder. An all-solid-state battery cell was manufactured in the same manner as in Example 1 except for this.
A thermogravimetric analysis of the additives of Synthesis Examples 1 to 4 and Comparative Synthesis Example 1 was performed within a temperature range of 30 to 300° C., and the results for Synthesis Examples 1 to 4 are shown in
The thermogravimetric analysis was performed by taking about 10 mg of the additive and using TGA8000 made by PerkinElmer Inc.
During the TGA analysis of each of the additives of Synthesis Examples 1 to 4, the results were similar to a theoretically calculated weight loss amount after generating nitrogen gas.
Accordingly, an azide group (azide, —N3) in each of the additives of Synthesis Examples 1 to 4 was decomposed at a high temperature of, e.g., about 140° C. or higher, and generated nitrogen (N2) and then, converted to a nitrene group (nitrene, —N).
Each of the all-solid-state battery cells of Examples 1 to 5 and Comparative Example 1 was analyzed within a temperature range of 40 to 200° C. through differential scanning calorimetry (DSC).
After charging each of the all-solid-state battery cells to 4.20 V, a sample for DSC was prepared in a glove box under an Ar atmosphere according to the following steps. A single cell was taken out from a laminate bag of an exterior body and drilled out to a hole with φ 2.5 mm with a mold. The sample was placed in a sample pan made of SUS, covered with a lid, and joined to seal the entrance with a press. This prepared sample for DSC was measured at a temperature range of 40 to 200° C. by using a DSC measuring device (DSC7000X) made by Hitachi High-Tech Science.
In the solid electrolyte layers of Examples 1 to 5, an azide group (azide, —N3) in each additive was decomposed to generate nitrogen (N2) and converted to a nitrene group (nitrene, —N) at a high temperature of, e.g., 140° C. or higher, during the first cycle.
Each of the solid electrolyte layers of Examples 1 to 5 and Comparative Example 1 was heated at 180° C. for 30 minutes and then, measured with respect to ionic conductivity changes, and the results are shown in Table 1.
The ionic conductivity was measured through electrochemical impedance spectroscopy (EIS). EIS was performed at an amplitude of about 10 mV and a frequency of 0.1 to 0.05 Hz at 0.1 MHz under an air atmosphere at 25° C.
Referring to Table 1, the additive Examples 1 to 5 sharply reduced ionic conductivity at a high temperature of, e.g., 180° C. or higher, and thus had an effect of shutting down ignition of the rechargeable lithium battery cells at a lower temperature than the ignition temperature.
By way of summation and review, some rechargeable lithium batteries may be lithium-ion batteries that use an electrolyte solution including a flammable organic solvent, and may have safety issues such as explosion or fire when problems such as collision or penetration occur. Accordingly, an all-solid-state battery using a solid electrolyte instead of an electrolyte solution has been considered. Among rechargeable lithium batteries, an all-solid-state battery refers to a battery in which all materials are solid, especially a battery that uses a solid electrolyte.
One or more embodiments may provide an additive for a rechargeable lithium battery that may help suppress ignition due to abnormal heat generation, regardless of the type of the rechargeable lithium battery.
The additive for a rechargeable lithium battery according to an embodiment can be applied to at least one of the components of a rechargeable lithium battery, regardless of the type of the rechargeable lithium battery, and may help suppress an ignition phenomenon due to abnormal heat generation.
Example embodiments have been disclosed herein, and although specific terms are employed, they are used and are to be interpreted in a generic and descriptive sense only and not for purposes of limitation. In some instances, as would be apparent to one of ordinary skill in the art as of the filing of the present application, features, characteristics, and/or elements described in connection with a particular embodiment may be used singly or in combination with features, characteristics, and/or elements described in connection with other embodiments unless otherwise specifically indicated. Accordingly, it will be understood by those of skill in the art that various changes in form and details may be made without departing from the spirit and scope of the present invention as set forth in the following claims.
| Number | Date | Country | Kind |
|---|---|---|---|
| 10-2023-0143196 | Oct 2023 | KR | national |
