Patent Application
20250038270
The present application claims priority to and the benefit of Korean Patent Application No. 10-2023-0098391, filed on Jul. 27, 2023, in the Korean Intellectual Property Office, the entire content of which is incorporated herein by reference.
Embodiments of the present disclosure described herein are related to rechargeable lithium battery.
Recently, with the rapid development of electronic devices that utilize batteries, such as mobile phones, laptop computers, and/or electric vehicles, the demand for rechargeable batteries with relatively high energy density and relatively high capacity is rapidly increasing. Accordingly, research and development to improve the performance of rechargeable lithium batteries is actively underway.
A rechargeable lithium battery includes a positive electrode and a negative electrode including an active material capable of intercalating and deintercalating lithium ions, and an electrolyte, and electrical energy is produced through oxidation and reduction reactions if (e.g., when) lithium ions are intercalated/deintercalated to/from the positive electrode and negative electrode.
One area of interest of research is to increase the density of the negative electrode for a rechargeable lithium battery. However, if (e.g., when) the density of the negative electrode is increased, then void volumes may decrease, which may increase the amount of electrolyte impregnated into the negative electrode, causing an increase in a thickness of the battery and a decrease of cycle-life.
Aspects according to one or more embodiments are directed toward a rechargeable lithium battery that increases the density of the negative electrode and suppresses the increase in thickness and decrease in cycle-life of the battery.
Aspects according to one or more embodiments are directed toward a rechargeable lithium battery that can increase the density of the negative electrode while suppressing or reducing an increase in battery thickness and a decrease in cycle-life.
Additional aspects will be set forth in part in the description which follows and, in part, will be apparent from the description, or may be learned by practice of the presented embodiments of the present disclosure.
According to one or more embodiments, a rechargeable lithium battery may include a positive electrode including a positive electrode active material; a negative electrode including a negative electrode active material; and an electrolyte, wherein an active mass density of the negative electrode is greater than or equal to about 1.7 g/cc, and the electrolyte includes a lithium salt; a non-aqueous organic solvent; and an additive represented by Chemical Formula 1:
Hereinafter, embodiments of the present disclosure will be described in more detail. However, these embodiments are examples, the present disclosure is not limited thereto and the present disclosure is defined by the scope of claims.
As utilized herein, if (e.g., when) specific definition is not otherwise provided, it will be understood that if (e.g., 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.
As utilized herein, if (e.g., when) specific definition is not otherwise provided, the singular may also include the plural. In one or more embodiments, unless otherwise specified, “A or B” may refer to “including A, including B, or including A and B.”
As utilized herein, expressions such as “at least one of”, “one of”, and “of (e.g., selected from among)”, when preceding a list of elements, modify the entire list of elements and do not modify the individual elements of the list. For example, “at least one of a, b or c”, “at least one selected from among a, b and c”, and/or the like, may indicate only a, only b, only c, both (e.g., simultaneously) a and b, both (e.g., simultaneously) a and c, both (e.g., simultaneously) b and c, all of a, b, and c, or variations thereof.
The term utilized herein is intended to describe only a specific embodiment and is not intended to limit the present disclosure. As utilized herein, the singular forms “a,” “an,” and “the” are intended to include the plural forms, including “at least one,” unless the content (e.g., amount) clearly indicates otherwise. “At least one” should not be construed as being limited to the singular. As utilized herein, the term “and/or” includes any and all combinations of one or more of the associated listed items. The terms “includes,” “including,” “comprises,” and/or “comprising,” when utilized in the detailed description, specify a presence of stated features, regions, integers, steps, operations, elements, and/or components, but do not preclude the presence or addition of one or more other features, regions, integers, steps, operations, elements, components, and/or groups thereof.
Spatially relative terms such as “beneath,” “below,” “lower,” “above,” and “upper” may be utilized herein to easily describe one element or feature's relationship to another element or feature. It will be understood that the spatially relative terms are intended to encompass different orientations of a device in utilize or operation in addition to the orientation illustrated in the drawings. For example, when a device in the drawings is turned over, elements described as “below” or “beneath” other elements or features would then be “above” or “over” the other elements or features. In some embodiments, the example term “below” may encompass both (e.g., simultaneously) orientations of above and below. The device may be otherwise oriented (rotated 90 degrees or at other orientations), and the spatially relative terms utilized herein may be interpreted accordingly.
The term “metal” as utilized herein includes all of metals and metalloids such as silicon and germanium in an elemental or ionic state.
The term “alloy” as utilized herein refers to a mixture of two or more metals.
The term “electrode active material” as utilized herein refers to an electrode material that may undergo lithiation and delithiation.
The term “composite cathode active material” as utilized herein refers to a cathode material that may undergo lithiation and delithiation.
The term “anode active material” as utilized herein refers to an anode material that may undergo lithiation and delithiation.
The terms “lithiate” and “lithiating” as utilized herein refer to a process of adding lithium to an electrode active material.
The terms “delithiate” and “delithiating” as utilized herein refer to a process of removing lithium from an electrode active material.
The terms “charge” and “charging” as utilized herein refer to a process of providing electrochemical energy to a battery.
The terms “discharge” and “discharging” as utilized herein refer to a process of removing electrochemical energy from a battery.
The terms “positive electrode” and “cathode” as utilized herein refer to an electrode at which electrochemical reduction and lithiation occur during a discharging process.
The terms “negative electrode” and “anode” as utilized herein refer to an electrode at which electrochemical oxidation and delithiation occur during a discharging process.
As utilized herein, the term “substantially” and similar terms are utilized as terms of approximation and not as terms of degree, and are intended to account for the inherent deviations in measured or calculated values that would be recognized by those of ordinary skill in the art. Also, the term “about” and similar terms, when utilized herein in connection with a numerical value or a numerical range, are inclusive of the stated value and a value within an acceptable range of deviation for the particular value as determined by one of ordinary skill in the art, considering the measurement in question and the error associated with measurement of the particular quantity (e.g., the limitations of the measurement system). For example, “about” may refer to within one or more standard deviations, or within ±30%, 20%, 10%, 5% of the stated value.
Also, any numerical range recited herein is intended to include all sub-ranges of the same numerical precision subsumed within the recited range. For example, a range of “1.0 to 10.0” is intended to include all subranges between (and including) the recited minimum value of 1.0 and the recited maximum value of 10.0, that is, having a minimum value equal to or greater than 1.0 and a maximum value equal to or less than 10.0, such as, for example, 2.4 to 7.6. Any maximum numerical limitation recited herein is intended to include all lower numerical limitations subsumed therein and any minimum numerical limitation recited in this specification is intended to include all higher numerical limitations subsumed therein. Accordingly, Applicant reserves the right to amend this specification, including the claims, to expressly recite any sub-range subsumed within the ranges expressly recited herein.
As utilized herein, “a combination thereof” may refer to a mixture of constituents, a stack, a composite, a copolymer, an alloy, a blend, and a reaction product.
As utilized herein, the “active mass density of the negative electrode” is a value calculated by dividing a weight of the components (active material, conductive material, binder, and/or the like) excluding the current collector in the negative electrode by a volume thereof.
As utilized herein, if (e.g., when) a definition is not otherwise provided, in chemical formulae, hydrogen is bonded at the position if (e.g., when) a chemical bond is not drawn where supposed to be given.
As utilized herein, if (e.g., when) a definition is not otherwise provided, refers to a portion linked to the same or different atom or chemical formula.
In this specification, “number average molecular weight” is a value measured by gel permeation chromatography (GPC, PL GPC220, Agilent Technologies) and corrected with a cubic function utilizing polystyrene.
One or more embodiments provide a rechargeable lithium battery including a positive electrode including a positive electrode active material; a negative electrode including a negative electrode active material; and an electrolyte, wherein an active mass density of the negative electrode is greater than or equal to about 1.7 g/cc, and the electrolyte includes a lithium salt; a non-aqueous organic solvent; and an additive represented by Chemical Formula 1:
The additive functions as a surfactant having both (e.g., simultaneously) hydrophilic and hydrophobic groups in one molecule.
The additive includes a *—[O—CH(R1)—CH2]y—* block at the center of the molecule, and a *—[O—CH2—CH2]x—* block and a *—[O—CH2—CH2]z—* block on both sides (e.g., opposite sides) of the molecule, respectively. Herein, the *—[O—CH(R1)—CH2]y—* is a hydrophobic block and the *—[O—CH2—CH2]x—* block and *—[O—CH2—CH2]z—* block are each hydrophilic blocks.
Accordingly, if (e.g., when) an electrolyte including the additive is utilized, wettability of the positive electrode and negative electrode is improved, lithium cation (Li+) are uniformly (substantially uniformly) formed at the interface between the positive electrode and the electrolyte, and a stable SEI film is formed at the interface between the negative electrode and the electrolyte, suppressing or reducing the precipitation of lithium dendrites.
Therefore, by utilizing an electrolyte including the above additive, while increasing the active mass density of the negative electrode to about 1.7 g/cc or more, the increase in battery thickness and decrease in cycle-life may be suppressed or reduced.
Hereinafter, a rechargeable lithium battery according to one or more embodiments will be described in more detail.
Generally, suitable rechargeable lithium batteries utilize a negative electrode with an active mass density of less than about 1.7 g/cc, but a rechargeable lithium battery according to one or more embodiments uses a negative electrode with a mixture density of greater than or equal to about 1.7 g/cc.
The upper limit for the active mass density of the negative electrode is not particularly limited, but may be less than or equal to about 2.0 g/cc, less than or equal to about 1.9 g/cc, or less than or equal to about 1.8 g/cc.
In the rechargeable lithium battery according to one or more embodiments, by utilizing an electrolyte including the above additive, an increase in the thickness and a decrease in the cycle-life of the battery can be suppressed or reduced even if the negative electrode is increased in density.
For example, the rechargeable lithium battery may have an upper charge limit voltage of greater than or equal to about 4.5 V.
In Chemical Formula 1, R1 is a hydrogen atom or a C1 to C10 alkyl group.
For example, R1 may be a methyl group.
In Chemical Formula 1, x, y, and z are independently integers of 1 to 20.
Herein, a mole ratio of x:y may be about 10:1 to about 1:10, about 5:1 to about 1:5, or about 3:1 to about 1:3. In one or more embodiments, a mole ratio of y:z may be about 10:1 to about 1:10, about 5:1 to about 1:5, or about 3:1 to about 1:3.
The additive may have a number average molecular weight in a range of about 500 g/mol to about 10,000 g/mol, about 700 g/mol to about 8,000 g/mol, or about 1,000 g/mol to about 2,000 g/mol.
If (e.g., when) the additive has a number average molecular weight that is out of the ranges described above, because viscosity of an electrolyte including the additive excessively increases, then its wettability to positive and negative electrodes may decrease. In contrast, if (e.g., when) the number average molecular weight of the additive is less than the ranges, its effect as a surfactant may be insignificant.
The additive may be represented by Chemical Formula 1-1:
The additive represented by Chemical Formula 1-1 may be poly(ethylene glycol)-b-poly(propylene glycol)-b-poly(ethylene glycol) and PEG-b-PPG-b-PEG). In Chemical Formula 1-1, x, y, and z are equally defined as described above.
The additive may be included in an amount of about 0.1 wt % to about 5 wt %, about 0.2 wt % to about 2 wt %, or about 0.5 wt % to about 1 wt % based on a total amount of 100 wt % of the electrolyte.
If the additive is included in excess of the above ranges, viscosity of the electrolyte including the additive may increase excessively, and wettability of the positive electrode and the negative electrode may actually decrease. In contrast, if the content (e.g., amount) of the additive is included in an amount below the above ranges, its effect as a surfactant may be minimal.
The non-aqueous organic solvent serves as a medium for transmitting ions taking part in the electrochemical reaction of a battery.
The non-aqueous organic solvent may be a carbonate-based, ester-based, ether-based, ketone-based, or alcohol-based solvent, an aprotic solvent, and/or a combination thereof (e.g., a suitable combination thereof).
The carbonate-based solvent may include dimethyl carbonate (DMC), diethyl carbonate (DEC), dipropyl carbonate (DPC), methylpropyl carbonate (MPC), ethylpropyl carbonate (EPC), methylethyl carbonate (MEC), ethylene carbonate (EC), propylene carbonate (PC), butylene carbonate (BC), and/or the like. The ester-based solvent may include methyl acetate, ethyl acetate, n-propyl acetate, dimethylacetate, methyl propionate, ethyl propionate, propyl propionate, decanolide, mevalonolactone, valerolactone, caprolactone, and/or the like.
The ether-based solvent may include dibutyl ether, tetraglyme, diglyme, dimethoxyethane, 2-methyltetrahydrofuran, 2,5-dimethyltetrahydrofuran, tetrahydrofuran, and/or the like. The ketone-based solvent may include cyclohexanone and/or the like. The alcohol-based solvent may include ethyl alcohol, isopropyl alcohol, and/or the like, and the aprotic solvent may include nitriles such as R—CN (wherein R is a C2 to C20 linear, branched, or cyclic hydrocarbon group, a double bond, an aromatic ring, or an ether group), amides such as dimethylformamide, dioxolanes such as 1,3-dioxolane or 1,4-dioxolane, sulfolanes, and/or the like.
The non-aqueous organic solvent may be utilized alone or in combination of two or more.
In the latter case, the non-aqueous organic solvent may include a carbonate-based solvent and a propionate-based solvent.
The propionate-based solvent may be included in an amount of greater than or equal to about 70 volume % based on a total amount of 100 volume % of the non-aqueous organic solvent. In this case, high-voltage and/or high-temperature characteristics of the rechargeable lithium battery can be improved.
For example, the non-aqueous organic solvent may be a mixed solvent of ethylene carbonate (EC), propylene carbonate (PC), and propyl propionate (PP).
The lithium salt dissolved in the organic solvent supplies lithium ions in a battery, enables a basic operation of a rechargeable lithium battery, and improves transportation of the lithium ions between positive and negative electrodes.
LiPF6 may be utilized as the lithium salt.
A concentration of the lithium salt may be about 0.1 M to about 2.0 M.
The positive electrode active material may be a compound (lithiated intercalation compound) capable of intercalating and deintercallating lithium. For example, one or more types (kinds) of composite oxides, of lithium and a metal selected from among cobalt, manganese, nickel, and combinations thereof, may be utilized.
The composite oxide may be a lithium transition metal composite oxide, and specific examples may include lithium nickel-based oxide, lithium cobalt-based oxide, lithium manganese-based oxide, a lithium iron phosphate-based compound, cobalt-free lithium nickel-manganese-based oxide, and/or a combination thereof (e.g., a suitable combination thereof).
As an example, a compound represented by any of (e.g., selected from among) the following chemical formulas may be utilized: LiaA1-bXbO2-cDc (0.90≤a≤1.8, ≤b≤0.5, 0≤c≤0.05); LiaMn2-bXbO4-cDc (0.90≤a≤1.8, 0≤b≤0.5, 0≤c≤0.05); LiaNi1-b-cCobXcO2-aDa (0.90≤a≤1.8, 0≤b≤0.5, 0≤c≤0.5, 0<α<2); LiaNi1-b-cMnbXcO2-aDa (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); and/or LiaFePO4 (0.90≤a≤1.8).
In the above chemical formulas, A is Ni, Co, Mn, and/or a combination thereof (e.g., a suitable combination thereof); X is Al, Ni, Co, Mn, Cr, Fe, Mg, Sr, V, a rare earth element, and/or a combination thereof (e.g., a suitable combination thereof); D is O, F, S, P, and/or a combination thereof (e.g., a suitable combination thereof); G is Al, Cr, Mn, Fe, Mg, La, Ce, Sr, V, and/or a combination thereof (e.g., a suitable combination thereof); and L1 is Mn, Al, and/or a combination thereof (e.g., a suitable combination thereof).
As an example, the positive electrode active material may have a nickel content (e.g., amount) of greater than or equal to about 80 mol %, greater than or equal to about 85 mol %, greater than or equal to about 90 mol %, greater than or equal to about 91 mol %, or greater than or equal to about 94 mol % based on about 100 mol % of metals excluding lithium in the lithium transition metal composite oxide. In one or more embodiments, the positive electrode active material may be a relatively high nickel-based positive electrode active material of less than or equal to about 99 mol % based on about 100 mol % of metals excluding lithium in the lithium transition metal oxide. The relatively high-nickel-based positive electrode active materials can achieve relatively high capacity and can be applied to relatively high-capacity, relatively high-density rechargeable lithium batteries.
The positive electrode active material may be, for example, lithium nickel-based oxide represented by Chemical Formula 11, lithium cobalt-based oxide represented by Chemical Formula 12, a lithium iron phosphate-based compound represented by Chemical Formula 13, and cobalt-free lithium nickel manganese-based oxide represented by Chemical Formula 14, and/or a combination thereof (e.g., a suitable 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 one or more elements selected from among Al, B, Ba, Ca, Ce, Co, Cr, Cu, Fe, Mg, Mn, Mo, Nb, Si, Sn, Sr, Ti, V, W, and Zr, and X is one or more elements selected from among F, P, and 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 is one or more elements selected from among Al, B, Ba, Ca, Ce, Cr, Cu, Fe, Mg, Mn, Mo, Ni, Se, Si, Sn, Sr, Ti, V, W, Y, Zn, and Zr, and X is one or more elements selected from among F, P, and 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 is one or more elements selected from among Al, B, Ba, Ca, Ce, Co, Cr, Cu, Mg, Mn, Mo, Ni, Se, Si, Sn, Sr, Ti, V, W, Y, Zn, and Zr, and X is one or more elements selected from among F, P, and 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 is one or more elements selected from among Al, B, Ba, Ca, Ce, Cr, Fe, Mg, Mo, Nb, Si, Sn, Sr, Ti, V, W, and Zr, and X is one or more elements selected from among F, P, and S.
In particular, the electrolyte of the above-described embodiment can significantly improve high-voltage and/or high-temperature characteristics of a battery utilizing the lithium cobalt-based oxide represented by Chemical Formula 12.
The positive electrode for a rechargeable lithium battery may include a current collector and a positive electrode active material layer on the current collector. The positive electrode active material layer may include a positive electrode active material and may further include a binder and/or a conductive material.
For example, the positive electrode may further include an additive that can function as a sacrificial positive electrode.
A content (e.g., amount) of the positive electrode active material may be about 90 wt % to about 99.5 wt %, and a content (e.g., amount) of the binder and the conductive material may be about 0.5 wt % to about 5 wt %, respectively based on about 100 wt % of the positive electrode active material layer.
The binder serves 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/or the like, as non-limiting examples.
The conductive material may be utilized to impart conductivity (e.g., electrical conductivity) to the electrode. Any material that does not cause chemical change (e.g., does not cause an undesirable chemical change in the rechargeable lithium battery) and conducts electrons can be utilized in the battery. Examples of the conductive material may include a carbon-based material such as natural graphite, artificial graphite, carbon black, acetylene black, ketjen black, a carbon fiber, a carbon nanofiber, and carbon nanotube; a metal-based material containing copper, nickel, aluminum, silver, and/or the like, in a form of a metal powder or a metal fiber; a conductive polymer such as a polyphenylene derivative; or a mixture thereof.
Al may be utilized as the current collector, but the present disclosure is not limited thereto.
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-based negative electrode active material, for example, crystalline carbon, amorphous carbon, and/or a combination thereof (e.g., a suitable 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, and/or the like.
The lithium metal alloy may include lithium and a metal selected from among Na, K, Rb, Cs, Fr, Be, Mg, Ca, Sr, Si, Sb, Pb, In, Zn, Ba, Ra, Ge, Al, and Sn.
The material capable of doping/dedoping lithium may be a Si-based negative electrode active material or a Sn-based negative electrode active material. The Si-based negative electrode active material may include silicon, a silicon-carbon composite, SiOx (0<x<2), a Si-Q alloy (where Q is selected from among an alkali metal, an alkaline-earth metal, a Group 13 element, a Group 14 element (excluding Si), a Group 15 element, a Group 16 element, a transition metal, a rare earth element, and/or a combination thereof (e.g., a suitable combination thereof)). The Sn-based negative electrode active material may include Sn, SnOx (0<x≤2) (e.g., SnO2), a Sn-based alloy, and/or a combination thereof (e.g., a suitable combination thereof).
The silicon-carbon composite may be a composite of silicon and amorphous carbon. According to one or more embodiments, the silicon-carbon composite may be in a form of silicon particles and amorphous carbon coated on the surface of the silicon particles. For example, the silicon-carbon composite may include a secondary particle (core) in which primary silicon particles are assembled, and an amorphous carbon coating layer (shell) on the surface of the secondary particle. The amorphous carbon may also be between the primary silicon particles, and, for example, the primary silicon particles may be coated with the amorphous carbon. The secondary particle may exist dispersed in an amorphous carbon matrix.
The silicon-carbon composite may further include crystalline carbon. For example, the silicon-carbon composite may include a core including crystalline carbon and silicon particles and an amorphous carbon coating layer on a surface of the core.
The Si-based negative electrode active material or the Sn-based negative electrode active material may be utilized in combination with a carbon-based negative electrode active material.
A negative electrode for a rechargeable lithium battery includes a current collector and a negative electrode active material layer on the current collector. The negative electrode active material layer includes a negative electrode active material and may further include a binder and/or a conductive material.
For example, the negative electrode active material layer may include about 90 wt % to about 99 wt % of the negative electrode active material, about 0.5 wt % to about 5 wt % of the binder, and about 0.5 wt % to about 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 include a non-aqueous binder, an aqueous binder, a dry binder, and/or a combination thereof (e.g., a suitable combination thereof).
The non-aqueous binder may include polyvinyl chloride, carboxylated polyvinyl chloride, polyvinyl fluoride, an ethylene propylene copolymer, polystyrene, polyurethane, polytetrafluoroethylene, polyvinylidene fluoride, polyethylene, polypropylene, polyamideimide, polyimide, and/or a combination thereof (e.g., a suitable combination thereof).
The aqueous binder may be selected from among a styrene-butadiene rubber, a (meth)acrylated styrene-butadiene rubber, a (meth)acrylonitrile-butadiene rubber, (meth)acrylic rubber, a butyl rubber, a fluoro rubber, polyethylene oxide, polyvinylpyrrolidone, polyepichlorohydrin, polyphosphazene, poly(meth)acrylonitrile, an ethylene propylene diene copolymer, polyvinylpyridine, chlorosulfonated polyethylene, latex, a polyester resin, a (meth)acrylic resin, a phenol resin, an epoxy resin, polyvinyl alcohol, and/or a combination thereof (e.g., a suitable combination thereof).
When an aqueous binder is utilized as the negative electrode binder, it may further include a cellulose-based compound capable of imparting viscosity. The cellulose-based compound includes one or more of carboxymethyl cellulose, hydroxypropylmethyl cellulose, methyl cellulose, or alkali metal salts thereof. The alkali metal may be Na, K, or Li.
The dry binder may be a polymer material capable of being fiberized, and may be, for example, polytetrafluoroethylene, polyvinylidene fluoride, polyvinylidene fluoride-hexafluoropropylene copolymer, polyethylene oxide, and/or a combination thereof (e.g., a suitable combination thereof).
The conductive material is included to provide electrode conductivity, and any electrically conductive material may be utilized as a conductive material unless it causes a chemical change. Examples of the conductive material may be a carbon-based material such as natural graphite, artificial graphite, carbon black, acetylene black, ketjen black, a carbon fiber, a carbon nanofiber, a carbon nanotube, and/or the like; a metal-based material such as copper, nickel, aluminum silver, and/or the like in a form of a metal powder or a metal fiber; a conductive polymer such as a polyphenylene derivative; or a mixture thereof.
The negative electrode current collector may include one selected from among 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, and/or a combination thereof (e.g., a suitable combination thereof), but the present disclosure is not limited thereto.
Depending on the type or kind of the rechargeable lithium battery, a separator may be present between the positive electrode and the negative electrode. The separator may include polyethylene, polypropylene, polyvinylidene fluoride, or a multilayer film of two or more layers thereof, and a mixed multilayer film such as a polyethylene/polypropylene two-layer separator, polyethylene/polypropylene/polyethylene three-layer separator, polypropylene/polyethylene/polypropylene three-layer separator, and/or the like.
The separator may include a porous substrate and a coating layer including an organic material, an inorganic material, and/or a combination thereof (e.g., a suitable combination thereof) on one or both surfaces (e.g., opposite surfaces) of the porous substrate.
The porous substrate may be a polymer film formed of any one selected from among polymer polyolefin (such as polyethylene and/or polypropylene), polyester (such as polyethylene terephthalate and/or polybutylene terephthalate), polyacetal, polyamide, polyimide, polycarbonate, polyether ketone, polyarylether ketone, polyether ketone, polyetherimide, polyamideimide, polybenzimidazole, polyethersulfone, polyphenylene oxide, a cyclic olefin copolymer, polyphenylene sulfide, polyethylene naphthalate, a glass fiber, and polytetrafluoroethylene (e.g., TEFLON), or a copolymer or/or mixture of two or more thereof.
The organic material may be a polyvinylidene fluoride-based polymer or a (meth)acryl-based polymer.
The inorganic material may include inorganic particles selected from among Al2O3, SiO2, TiO2, SnO2, CeO2, MgO, NiO, CaO, GaO, ZnO, ZrO2, Y2O3, SrTiO3, BaTiO3, Mg(OH)2, boehmite, and/or a combination thereof (e.g., a suitable combination thereof), but the present disclosure is not limited thereto.
The organic material and the inorganic material may be mixed in one coating layer, or a coating layer including an organic material and a coating layer including an inorganic material may be stacked.
The rechargeable lithium battery may be classified into cylindrical, prismatic, pouch, or coin-type or kind batteries, and/or the like depending on their shape.
The rechargeable lithium battery according to some embodiments may be applied to automobiles, mobile phones, and/or one or more suitable types (kinds) of electrical devices, but the present disclosure is not limited thereto.
Hereinafter, examples of the present disclosure and comparative examples are described. These examples, however, are not in any sense to be interpreted as limiting the scope of the present disclosure.
Electrolytes and rechargeable lithium battery cells were prepared as follows.
About 1.3 M LiPF6 was dissolved in a non-aqueous organic solvent in which ethylene carbonate (EC), propylene carbonate (PC), and propyl propionate (PP) were mixed in a volume ratio of about 10:15:75, and about 0.2 wt % of the additive was added thereto to prepare an electrolyte.
The additive represented by Chemical Formula 1-1 was utilized:
Poly(ethylene glycol)-block or reduce-poly(propylene glycol)-block or reduce-poly(ethylene glycol) (PEG-b-PPG-b-PEG. CAS No.: 9003-11-6, x=1-20, y=1-20, z=1-20, number average molecular weight: 1,100 g/mol)
LiCoO2 as a positive electrode active material, polyvinylidene fluoride as a binder, and acetylene black as a conductive material were mixed respectively in a weight ratio of about 96:3:1, and then, dispersed in N-methyl pyrrolidone to prepare positive electrode active material slurry.
The positive electrode active material slurry was coated on an about 15 μm-thick Al foil, dried at about 100° C., and pressed to manufacture a positive electrode.
Artificial graphite as a negative electrode active material, a styrene-butadiene rubber binder, and carboxymethyl cellulose in a weight ratio of about 98:1:1 were dispersed in distilled water to prepare negative electrode active material slurry.
The negative electrode active material slurry was coated on an about 10 micrometer-thick (μm-thick) Cu foil, dried at about 100° C., and pressed to manufacture a negative electrode. At this time, an active mass density of the negative electrode was set to about 1.7 g/cc.
An electrode assembly was manufactured by assembling the positive electrode, the negative electrode, and a separator made of polyethylene with a thickness of about 10 μm, and the electrolyte was injected, to manufacture a rechargeable lithium battery cell.
An electrolyte and a rechargeable lithium battery cell were manufactured in substantially the same manner as in Example 1 except that the additive was added in an amount of about 0.5 wt % to prepare the electrolyte.
An electrolyte and a rechargeable lithium battery cell were manufactured in substantially the same manner as in Example 1 except that the additive was added in an amount of about 1 wt % to prepare the electrolyte.
An electrolyte and a rechargeable lithium battery cell were manufactured in substantially the same manner as in Example 1 except that the electrolyte was prepared by adding about 1 wt % of the additive, and the negative electrode was manufactured to have active mass density of about 1.75 g/cc.
An electrolyte and a rechargeable lithium battery cell were manufactured in substantially the same manner as in Example 1 except that the electrolyte was prepared by adding about 1 wt % of the additive, and the negative electrode was manufactured to have active mass density of about 1.8 g/cc.
An electrolyte and a rechargeable lithium battery cell were manufactured in substantially the same manner as in Example 1 except that the electrolyte was prepared by not adding the additive at all, and the negative electrode was manufactured to have active mass density of about 1.65 g/cc.
An electrolyte and a rechargeable lithium battery cell were manufactured in substantially the same manner as in Example 1 except that the electrolyte was prepared by not adding the additive at all, and the negative electrode was manufactured to have active mass density of about 1.67 g/cc.
An electrolyte and a rechargeable lithium battery cell were manufactured in substantially the same manner as in Example 1 except that the electrolyte was prepared by not adding the additive at all, and the negative electrode was manufactured to have active mass density of about 1.7 g/cc.
The negative electrode and rechargeable lithium battery cell were evaluated in the following manner.
The negative electrode according to Example 1 was manufactured as a specimen with width x (e.g., *) length=about 3 cm×about 5 cm. About 1 g of the electrolyte according to Example 1 was dropped on the specimen and left for about 20 minutes. Thereafter, an amount of electrolyte immersed in the specimen among about 100 wt % of the electrolyte dropped on the specimen was evaluated as a value from 0 to 5 according to the following criteria, and the evaluation results are shown in Table 1:
Examples 2 to 5 and Comparative Examples 1 to 3 were evaluated in substantially the same manner, and the evaluation results are shown in Table 1.
The rechargeable lithium battery cells were charged and discharged about 400 times under the conditions of about 25° C., about 2.0 C charge (CC/CV, 4.53 V, 0.025 C Cut-off)/about 1.0 C discharge (CC, 3 V Cut-off).
The thickness increase rates were calculated according to Equation 1, capacity retention rates were calculated according to Equation 2, and the results are shown in Table 2.
Thickness increase rate={(Full charge thickness after 400 cycles)−(Full charge thickness after 1 cycle)}/(Full charge thickness after 1 cycle)*100 Equation 1
In Equation 1, “full charge thickness” refers to a thickness of the rechargeable lithium battery cells measured after charging at about SOC 100% (if (e.g., when) the total charge capacity of the battery is set at about 100%, charged to about 100% charge capacity) after each cycle.
Capacity retention rate=(discharge capacity after 400 cycles/discharge capacity after 1 cycle)*100 Equation 2
Referring to Tables 1 and 2, an electrolyte prepared by not adding the additives at all (Comparative Examples 1 to 3), as active mass density of a negative electrode was increased from about 1.65 g/cc to about 1.7 g/cc, lowered impregnating property of the electrolyte to the negative electrode and increased a thickness of a battery cell, resulting in deteriorating a cycle-life.
However, when the negative electrodes had the same active mass density of about 1.7 g/cc, compared with an electrolyte not including the additive at all (Comparative Example 3), an electrolyte including the additive (Examples 1 to 3) exhibited increased impregnating property to a negative electrode, resulting in increasing a cycle-life.
Furthermore, an electrolyte concurrently (e.g., simultaneously) including the first and second additives, even though active mass density of a negative electrode was increased from about 1.7 g/cc to about 1.8 g/cc (Examples 4 and 5), suppressed or reduced an increase in a battery thickness and a decrease in a cycle-life.
In present disclosure, “not include a or any ‘component’”, “exclude a or any ‘component’”, “‘component’-free”, and/or the like refers to that the “component” not being added, selected or utilized as a component in the composition or compound, but the “component” of less than a suitable amount may still be included due to other impurities and/or external factors.
A battery management system (BMS) device, and/or any other relevant devices or components according to embodiments of the present disclosure described herein may be implemented utilizing any suitable hardware, firmware (e.g. an application-specific integrated circuit), software, or a combination of software, firmware, and hardware. For example, the one or more suitable components of the device may be formed on one integrated circuit (IC) chip or on separate IC chips. Further, the one or more suitable components of the device may be implemented on a flexible printed circuit film, a tape carrier package (TCP), a printed circuit board (PCB), or formed on one substrate. Further, the one or more suitable components of the device may be a process or thread, running on one or more processors, in one or more computing devices, executing computer program instructions and interacting with other system components for performing the one or more suitable functionalities described herein. The computer program instructions are stored in a memory which may be implemented in a computing device utilizing a standard memory device, such as, for example, a random access memory (RAM). The computer program instructions may also be stored in other non-transitory computer readable media such as, for example, a CD-ROM, flash drive, and/or the like. Also, a person of skill in the art should recognize that the functionality of one or more suitable computing devices may be combined or integrated into a single computing device, or the functionality of a particular computing device may be distributed across one or more other computing devices without departing from the scope of the present disclosure.
In present disclosure, “not include a or any ‘component’” “exclude a or any ‘component’”, “‘component’-free”, and/or the like refers to that the “component” not being added, selected or utilized as a component in the composition/structure, but the “component” of less than a suitable amount may still be included due to other impurities and/or external factors.
While this present disclosure has been described in connection with what is presently considered to be practical embodiments, it is to be understood that the present disclosure not limited to the disclosed embodiments, but, on the contrary, is intended to cover one or more suitable modifications and equivalent arrangements included within the spirit and scope of the appended claims, and equivalents thereof.
| Number | Date | Country | Kind |
|---|---|---|---|
| 10-2023-0098391 | Jul 2023 | KR | national |
