BATTERY

TECHNICAL FIELD

The disclosure relates to a battery, and more particularly to a lithium secondary battery.

BACKGROUND

In conventional liquid electrolyte lithium ion batteries, the energy storage cost per unit is high due to the low gravimetric energy density and the limited cycle life. However, unilaterally increasing the energy density of batteries can easily induce serial safety problems in electrochemical batteries, such as liquid leakage, battery swelling, heating, fuming, burning, explosion, and the like.

The liquid electrolyte used in a lithium secondary battery must not only meet the high working voltage requirements of positive electrodes but also exhibit high reducibility to the lithium metal. Conventional liquid electrolyte, however, is unable to achieve the aforementioned goals. Furthermore, the inorganic-based solid electrolyte and the organic-based solid electrolyte also have disadvantages of high interfacial resistance, high manufacturing difficulty, low ionic conductivity, and insufficient mechanical strength. Furthermore, the lithium metal may cause a change of quality of the solid electrolyte when the lithium metal contacts the solid electrolyte, thereby deteriorating the battery performance.

Accordingly, a novel design and structure of the battery is called for to solve the aforementioned problems, prolong the lifespan and enhance the battery performance.

SUMMARY

A detailed description is given in the following embodiments with reference to the accompanying drawings.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a schematic view showing the battery according to embodiments of the disclosure.

FIG. 2 is close-up schematic view of the region 2 in the solid electrolyte membrane of the battery as shown in FIG. 1.

FIG. 3 is a schematic view showing the battery according to some embodiments of the disclosure.

FIG. 4 is a schematic view showing the solid electrolyte membrane according to some embodiments of the disclosure.

FIGS. 5 and 6 are close-up schematic view of the region 5 in the solid electrolyte membrane of the battery as shown in FIG. 4.

FIG. 7 is a schematic view showing the solid electrolyte membrane according to some embodiments of the disclosure.

FIG. 8 is a graph plotting the result of the dynamic mechanical measurement analysis of the composite film (LLZOGS) and the solid electrolyte membrane (ML-LLZOGS).

FIG. 9 is a graph plotting the charge-discharge curves of the battery as disclosed in Example 1.

FIG. 10 is a graph plotting the resistance curves of the batteries as disclosed in Examples 2-4 and Comparative Example 1.

DETAILED DESCRIPTION

The battery of the disclosure is described in detail in the following description. In the following detailed description, for purposes of explanation, numerous specific details and embodiments are set forth in order to provide a thorough understanding of the present disclosure. The specific elements and configurations described in the following detailed description are set forth in order to clearly describe the present disclosure. It will be apparent, however, that the exemplary embodiments set forth herein are used merely for the purpose of illustration, and the inventive concept may be embodied in various forms without being limited to those exemplary embodiments. In addition, the drawings of different embodiments may use like and/or corresponding numerals to denote like and/or corresponding elements in order to clearly describe the present disclosure.

However, the use of like and/or corresponding numerals in the drawings of different embodiments does not suggest any correlation between different embodiments. As used herein, the term “about” in quantitative terms refers to plus or minus an amount that is general and reasonable to persons skilled in the art.

It should be noted that the elements or devices in the drawings of the disclosure may be present in any form or configuration known to those skilled in the art. In addition, the expression “a layer overlying another layer”, “ a layer is disposed above another layer”, “ a layer is disposed on another layer” and “ a layer is disposed over another layer” may refer to a layer that directly contacts the other layer, and they may also refer to a layer that does not directly contact the other layer, there being one or more intermediate layers disposed between the layer and the other layer.

The drawings described are only schematic and are non-limiting. In the drawings, the size, shape, or thickness of some of the elements may be exaggerated and not drawn on scale for illustrative purposes. The dimensions and the relative dimensions do not correspond to actual location to practice of the disclosure. The disclosure will be described with respect to particular embodiments and with reference to certain drawings but the disclosure is not limited thereto.

Moreover, the use of ordinal terms such as “first”, “second”, “third”, etc., in the disclosure to modify an element does not by itself connote any priority, precedence, or order of one claim element over another or the temporal order in which it is formed, but are used merely as labels to distinguish one claim element having a certain name from another element having the same name (but for use of the ordinal term) to distinguish the claim elements.

The disclosure provides a battery, such as lithium secondary battery. According to embodiments of the disclosure, the battery includes a positive electrode, a negative electrode, and a solid electrolyte membrane disposed between the positive electrode and the negative electrode. Due to the specific structural design of the solid electrolyte membrane (i.e. a laminated structure consisting of a first porous layer, an electrolyte layer, and a second porous layer), the dimensional stability, thermal stability, ionic conductivity and mechanical strength of the solid electrolyte membrane can be enhanced and the resistance of the solid electrolyte membrane can be reduced. Thus, the solid electrolyte membrane is suitable for use in concert with a negative electrode (such as a negative electrode with high reducibility) and a positive electrode (such as a positive electrode with high working voltage) of a lithium secondary battery. In addition, the negative electrode of the disclosure includes a modified layer disposed on the active layer surface of the negative electrode, wherein the modified layer can improve the lithium ionic mobility and avoid the deterioration of the battery performance caused by the direct contact of the solid electrolyte membrane and the negative electrode active layer. Accordingly, by means of the combination of the solid electrolyte membrane and the modified layer, the stability, energy density, and safety in use of the battery can be improved and the life cycle of the battery can be prolonged.

According to embodiments of the disclosure, the battery of the disclosure includes a positive electrode, a negative electrode, and a solid electrolyte membrane disposed between the positive electrode and the negative electrode. The positive electrode includes a positive electrode active layer. The negative electrode includes a negative electrode active layer and a modified layer disposed on the negative electrode active layer, wherein the modified layer includes a metal fluoride and a lithium-containing compound. The solid electrolyte membrane includes a first porous layer, an electrolyte layer, and a second porous layer, wherein the electrolyte layer is disposed between the first porous layer and the second porous layer.

FIG. 1 is a schematic view showing the battery 100 according to embodiments of the disclosure. As shown in FIG. 1, the battery 100 includes a negative electrode 10, a positive electrode 40, and a solid electrolyte membrane 20, the negative electrode 10 is separated from the positive electrode 40 by the solid electrolyte membrane 20. The negative electrode 10 can include a negative electrode active layer 12 and a modified layer 14, wherein the modified layer 14 is disposed on the negative electrode active layer 12. The negative electrode active layer 12 includes a negative electrode active material, wherein the negative electrode active material includes lithium, lithium alloy (such as LiAl, LiMg, LiZn, Li_4.4Pb, Li_4.4Sn, meso carbon micro bead (MCMB), vapor grown carbon fiber (VGCF), carbon nanotube (CNT), graphene, coke, graphite, carbon black, acetylene black, carbon fiber, glassy carbon, lithium-containing compound (such as Li₄Ti₅O₁₂, Li₃Bi, Li₃Cd, Li₃Sb, Li₄Si, LiC₆, Li₃FeN₂, Li₂₆Co_0.04N, or Li_2.6Cu_0.4N), silicon-based alloy, tin, tin-based alloy, or a combination thereof. According to embodiments of the disclosure, the negative electrode active layer 12 can further include a negative electrode current-collecting layer (not shown), and the negative electrode active material is disposed on the negative electrode current-collecting layer or disposed within the negative electrode current-collecting layer. According to embodiments of the disclosure, the negative electrode current-collecting layer can include a metal foil, such as aluminum foil or copper foil. The positive electrode 40 can be a positive electrode active layer, wherein the positive electrode active layer includes a positive electrode active material. According to embodiments of the disclosure, the positive electrode active material includes elementary sulfur, organic sulfide, sulfur carbon composite, metal-containing lithium oxide, metal-containing lithium sulfide, metal-containing lithium selenide, metal-containing lithium telluride, metal-containing lithium phosphide, metal-containing lithium silicide, metal-containing lithium boride, or a combination thereof. In particular, the metal is selected from a group of aluminum, vanadium, titanium, chromium, copper, molybdenum, niobium, iron, nickel, cobalt, and manganese. According to embodiments of the disclosure, the positive electrode active material can be lithium-cobalt oxide (LiCoO₂), lithium-nickel oxide (LiNiO₂), lithium-manganese oxide (LiMn₂O₄), lithium-manganese-cobalt oxide (LiMnCoO₄), lithium-cobalt-nickel-manganese oxide (LiCo_0.3Ni_0.3Mn_0.3O), lithium-cobalt phosphate (LiCoPO₄), lithium-manganese-chromium oxide (LiMnCrO₄), lithium-nickel-vanadium oxide (LiNiVO₄), lithium-manganese-nickel oxide (LiMn_1.5Ni_0.5O₄), lithium-cobalt-vanadium oxide (LiCoVO₄), or a combination thereof. According to embodiments of the disclosure, the positive electrode active layer can further include a positive electrode current-collecting layer (not shown), and the positive electrode active material is disposed on the positive electrode current-collecting layer or disposed within the positive electrode current-collecting layer. According to embodiments of the disclosure, the positive electrode current-collecting layer can include metal foil, such as aluminum foil or copper foil.

According to embodiments of the disclosure, the negative electrode can consist of the negative electrode active layer and the modified layer. According to embodiments of the disclosure, the negative electrode active layer can consist of the negative electrode active material. According to some embodiments of the disclosure, the negative electrode active layer can consist of the negative electrode active material and the negative electrode current-collecting layer.

As shown in FIG. 1, according to embodiments of the disclosure, the modified layer 14 is disposed between the solid electrolyte membrane 20 and the negative electrode active layer 12, thereby avoiding the deterioration of the battery performance caused by the direct contact of the solid electrolyte membrane 20 and the negative electrode active layer 12. In addition, the modified layer 14 can enhance the interfacial compatibility between the solid electrolyte membrane 20 and the negative electrode 10 and ionic conductivity, and increase the stability, safety in use, and life cycle of the battery.

According to embodiments of the disclosure, the thickness of the modified layer can be from about 1 μm to 10 μm, such as 3 μm. If the thickness of the modified layer is too high, the charge-discharge performance would be deteriorated due to the high interfacial impedance. If the thickness of the modified layer is too low, the interfacial compatibility between the solid electrolyte membrane 20 and the negative electrode 10 and the surface stability of the negative electrode 10 would not be improved. According to embodiments of the disclosure, the modified layer can include a metal fluoride and a lithium-containing compound, wherein the weight ratio of the metal fluoride to the lithium-containing compound is about 1:1 to 1:10, such as 1:2, 1:3, 1:4, 1:5, 1:6, 1:7, 1:8, or 1:9. According to embodiments of the disclosure, the metal fluoride can be copper fluoride, zinc fluoride, nickel fluoride, titanium fluoride, aluminum fluoride, silicon fluoride, or a combination thereof. According to embodiments of the disclosure, the lithium-containing compound used in the modified layer can be lithium nitrate, lithium trifluoromethanesulfonate, lithium hexafluorophosphate, lithium perchlorate, lithium thiocyanate, lithium hexafluoroarsenate, lithium bis(trifluoromethanesulfonyl)imide (LiTFSI), lithium bis(fluorosulfonyl)imide (LiFSI), or a combination thereof.

According to embodiments of the disclosure, the modified layer can further include an imide compound in order to further reduce the resistance of the modified layer and increase the stability of the solid electrolyte interphase, thereby prolonging the life cycle of the battery. According to embodiments of the disclosure, the imide compound can be succinimide compound, phthalimide compound, glutarimide compound, maleimide compound, or a combination thereof.

According to embodiments of the disclosure, the maleimide compound can include maleimide, bismaleimide, or a combination thereof. The maleimide can have a structure represented by Formula (I) or Formula (II):

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wherein R^ais C_1-8alkyl group, —RNH₂, —C(O)CH₃, —CH₂OCH₃, —CH₂S(O)CH₃, —C₆H₅, —CH₂(C₆H₅)CH₃, phenylene, diphenylene, cycloaliphatics, or silane-substituted aromatics; Y is H, C_1-8alkyl group, —S(O)—R^c, —CONH₂, or —C(CF₃)₃; R^bis independently H, F, Cl, Br, HSO₃, SO₂, or C_1-8alkyl group; R is C_1-8alkylene group; and, R^cis C_1-8alkyl group. According to embodiments of the disclosure, the maleimide can be maleimide-phenylmethane, phenyl-maleimide, methylphenyl maleimide, dimethylphenyl-maleimide, ethylenemaleimide, thio-maleimid, ketone-maleimid, methylene-maleinimid, maleinimidomethylether, maleimido-ethandiol, 4-phenylether-maleimid, 4, maleimido-phenylsulfone, or a combination thereof.

According to embodiments of the disclosure, the bismaleimide can have a structure represented by Formula (III) or (IV):

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wherein R^dis C_1-8alkylene group, —RNHR—, —C(O)CH₂—, —CH₂OCH₂—, —C(O)—, —O—, —O—O—, —S—, —S—S—, —S(O)—, —CH₂S(P)CH₂—, —(O)S(O)—, —C₆H₅—, —CH₂(C₆H₅)CH₂—, —CH₂(C₆H₅)(O)—, phenylene, diphenylene, substituted phenylene, or substituted diphenylene; R^eis C_1-8alkylene group, —C(O)—, —C(CH₃)₂—, —O—, —O—O—, —S—, —S—S—, —(O)S(O)—, or —S(O)—; and, R is C_1-8alkylene group. According to embodiments of the disclosure, the bismaleimide can be N,N′-bismaleimide-4,4′-diphenylmethane, [1,1′-(methylenedi-4,1-phenylene)bismaleimide], [N,N′-(1,1′-biphenyl-4,4′-diyl) bismaleimide], [N,N′-(4-methyl-1,3-phenylene)bismaleimide], [1,1′-(3,3′dimethyl-1,1′-biphenyl-4,4′-diyl)bismaleimide], N,N′-ethylenedimaleimide, [N,N′-(1,2-phenylene)dimaleimide], [N,N′-(1,3-phenylene)dimaleimide], N,N′-thiodimaleimide, N,N′-dithiodimaleimide, N,N′-ketonedimaleimide, N,N′-methylene-bis-maleinimide, bis-maleinimidomethyl-ether, [1,2-bis-(maleimido)-1,2-ethandiol], N,N′-4,4′-diphenylether-bis-maleimid, [4,4′-bis(maleimido)-diphenylsulfone], or a combination thereof.

According to embodiments of the disclosure, the content of the imide compound can be from about 10 wt % to 50 wt %, such as 15 wt %, 20 wt %, 25 wt %, 30 wt %, 35 wt %, 40 wt %, or 45 wt %, based on the weight of the modified layer. If the amount of the imide compound is too low, the resistance of the modified layer and the stability of the solid electrolyte interphase would not be further increased. If the amount of the imide compound is too high, the interfacial compatibility between the solid electrolyte membrane 20 and the negative electrode 10 and the ionic conductivity would not be improved.

According to embodiments of the disclosure, the modified layer 14 can consist of the metal fluoride, the lithium-containing compound, and the imide compound. According to embodiments of the disclosure, in order to increase the adhesive strength between the modified layer 14 and the negative electrode active layer 12, the modified layer 14 can further include an binder, wherein the binder is uniformly mixed with the metal fluoride, the lithium-containing compound, and the imide compound. The amount of the binder is not limited and can be optionally modified by a person of ordinary skill in the field, on the premise that there is a sufficient adhesive strength between the modified layer 14 and the negative electrode active layer 12 in order to prevent the modified layer 14 from peeling from the negative electrode active layer 12. For example, the content of the binder can be 1 wt % to 20 wt %, based on the total weight of the metal fluoride, the lithium-containing compound, and the imide compound. According to embodiments of the disclosure, the binder can include polyvinylidene fluoride, polytetrafluoroethylene (PTFE), polyvinyl alcohol (PVA), polyethylene glycol (PEG), carboxymethyl cellulose (CMC), styrene butadiene rubber (SBR), polyacrylate, polyacrylonitrile (PAN), or a combination thereof. In addition, according to embodiments of the disclosure, the modified layer 14 can be directly formed on the negative electrode active layer 12 (i.e. there is no other layer between the modified layer 14 and the negative electrode active layer 12). Furthermore, the modified layer 14 can be fixed on the negative electrode active layer 12 via a binder.

According to embodiments of the disclosure, the method for manufacturing the negative electrode can include the following steps. First, the negative electrode active layer is provided. Next, the metal fluoride, the lithium-containing compound, and the imide compound are dispersed in a solvent (such as 1,2-diethoxyethane, 1,2-dimethoxyethane, 1,2-dibutoxyethane, tetrahydrofuran (THF), 2-methyl tetrahydrofuran, dimethylacetamide (DMAC), or a combination thereof), obtaining a solution. The solution has a solid content of 1 wt % to 10 wt %. Next, the solution was coated on the surface of the negative electrode active layer via a coating process to form a coating, wherein the average amount of the solution disposed on the surface of the negative electrode active layer is about 1 μL/cm²to 20 μL/cm². The coating process can be screen printing, spin coating, bar coating, blade coating, roller coating, solvent casting, or dip coating. Next, the coating is subjected to a drying process (with a process temperature from 25° C. to 80° C)., obtaining the modified layer.

As shown in FIG. 1, the solid electrolyte membrane 20 is disposed between the negative electrode 10 and the positive electrode 40, and the solid electrolyte membrane 20 includes a first porous layer 22, an electrolyte layer 24, and a second porous layer 26. As shown in FIG. 1, the solid electrolyte membrane 20 sequentially includes the first porous layer 22, the electrolyte layer 24, and the second porous layer 26 in the direction from the negative electrode to the positive electrode. Namely, the electrolyte layer 24 is disposed between the first porous layer 22 and the second porous layer 26. FIG. 2 is close-up schematic view of the region 2 in the solid electrolyte membrane 20 of the battery 100 as shown in FIG. 1. As shown in FIG. 2, the first porous layer 22 can include a polymer 21 and a plurality of pores 23, wherein the plurality of pores 23 are distributed in the first porous layer 22. According to embodiments of the disclosure, the first porous layer 22 can have a porosity of about 10 vol % to 90 vol %, such as about 15 vol %, 20 vol %, 30 vol %, 40 vol %, 50 vol %, 60 vol %, 70 vol %, 80 vol %, or 85 vol %. According to embodiments of the disclosure, the battery of the disclosure can optionally employ a first porous layer 22 with various porosity. According to embodiments of the disclosure, in order to increase the dimensional stability and the mechanical strength of the solid electrolyte membrane 20, the first porous layer 22 can be a dense layer. Namely, the first porous layer 22 can have a porosity of about 10 vol % to 40 vol %. According to some embodiments of the disclosure, in order to increase the ionic conductivity of the solid electrolyte membrane 20 or to facilitate the formation of the organic-inorganic composite structure, the first porous layer 22 can be a loose layer. Namely, the first porous layer 22 can have a porosity of about 40 vol % to 90 vol %. The porosity can be measured by the following equation: P=V1/V2×100%, wherein P is the porosity, V1 is the volume of the pores 23 of the first porous layer 22, and V2 is the total volume of the first porous layer 22. A porosimeter can be used to determine the porosity. According to embodiments of the disclosure, the average pore size of the plurality of pores 23 can be from 10 nm to 5 μm, such as from 20 nm to 3 μm, or from 50 nm to 3 μm. The average pore size can be determined by the method according to ISO 15901-2. According to embodiments of the disclosure, the thickness of the first porous layer 22 can be from about 1 μm to 30 μm, such as 2 μm or 20 μm. If the thickness of the first porous layer 22 is too high, theionic mobility would be deteriorated due to the high interfacial impedance. If the thickness of the first porous layer 22 is too low, the cycling stability of the battery would be deteriorated. According to embodiments of the disclosure, the polymer can be polydimethylsiloxane (PDMS), polyvinylchloride (PVC), polycarbonate (PC), polypropylene (PP), polyacrylic acid (PAA), poly(methyl methacrylate) (PMMA), polyethylene terephthalate (PET), polyacrylonitrile (PAN), polytetrafluoroethylene (PTFE), polyvinylidene fluoride (PVDF), perfluoroalkoxy alkane (PFA), fluorinated ethylene propylene (FEP), poly(vinylidene fluoride-co-hexafluoropropylene) (PVDF-HFP), styrene-butadiene rubber (SBR), nitrile-butadiene rubber (NBR), or a combination thereof. According to embodiments of the disclosure, the number average molecular weight of the polymer can be from about 5,000 to 5,000,000, such as about 100,000, 200,000, 500,000, 800,000, 1,000,000, 2,000,000, 3,000,000, or 4,000,000. According to embodiments of the disclosure, the polymer can be fluorine-containing polymer, such as polytetrafluoroethylene (PTFE), polyvinylidene fluoride (PVDF), perfluoroalkoxy alkane (PFA), fluorinated ethylene propylene (FEP), poly(vinylidene fluoride-co-hexafluoropropylene) (PVDF-HFP), or a combination thereof. Due to the hydrophobicity of the fluorine-containing polymer, the moisture flux passing through the fluorine-containing polymer is reduced, thereby avoiding the deterioration of the battery performance.

The second porous layer 26 can include a polymer and a plurality of pores, wherein the plurality of pores are distributed in the second porous layer 26. According to embodiments of the disclosure, the second porous layer 26 can have a porosity of about 10 vol % to 90 vol %, such as about 15 vol %, 20 vol %, 30 vol %, 40 vol %, 50 vol %, 60 vol %, 70 vol %, 80 vol %, or 85 vol %. According to embodiments of the disclosure, the porosity of the second porous layer 26 of the battery of the disclosure can be optionally adjusted.

According to embodiments of the disclosure, in order to increase the dimensional stability and the mechanical strength of the solid electrolyte membrane 20, the second porous layer 26 can be a dense layer. Namely, the second porous layer 26 can have a porosity of about 10 vol % to 40 vol%. According to some embodiments of the disclosure, in order to increase the ionic conductivity of the solid electrolyte membrane 20 or to facilitate the formation of the organic-inorganic composite structure, the second porous layer 26 can be a loose layer. Namely, the second porous layer 26 can have a porosity of about 40 vol % to 90 vol %. The porosity can be measured by the following equation: P=V1/V2×100%, wherein P is the porosity, V1 is the volume of the pores 23 of the second porous layer 26, and V2 is the total volume of the second porous layer 26. A porosimeter can be used to determine the porosity. According to embodiments of the disclosure, the average pore size of the plurality of pores can be from 10 nm to 5 μm, such as from 20 nm to 3 μm, or from 50 nm to 3 μm. According to embodiments of the disclosure, the thickness of the second porous layer 26 can be from about 1 to 30 μm, such as 2 μm or 20 μm. If the thickness of the second porous layer 26 is too high, the ionic mobility capacity would be deteriorated due to the high interfacial impedance. If the thickness of the second porous layer 26 is too low, the cycling stability of the battery would be deteriorated.

According to embodiments of the disclosure, the polymer can be polydimethylsiloxane (PDMS), polyvinylchloride (PVC), polycarbonate (PC), polypropylene (PP), polyacrylic acid (PAA), poly(methyl methacrylate) (PMMA), polyethylene terephthalate (PET), polyacrylonitrile (PAN), polytetrafluoroethylene (PTFE), polyvinylidene fluoride (PVDF), perfluoroalkoxy alkane (PFA), fluorinated ethylene propylene (FEP), poly(vinylidene fluoride-co-hexafluoropropylene) (PVDF-HFP), styrene-butadiene rubber (SBR), nitrile-butadiene rubber (NBR), or a combination thereof. According to embodiments of the disclosure, the number average molecular weight of the polymer can be from about 5,000 to 5,000,000, such as about 100,000, 200,000, 500,000, 800,000, 1,000,000, 2,000,000, 3,000,000, or 4,000,000. According to embodiments of the disclosure, the polymer can be fluorine-containing polymer, such as polytetrafluoroethylene (PTFE), polyvinylidene fluoride (PVDF), perfluoroalkoxy alkane (PFA), fluorinated ethylene propylene (FEP), poly(vinylidene fluoride-co-hexafluoropropylene) (PVDF-HFP), or a combination thereof. Due to the hydrophobicity of the fluorine-containing polymer, the moisture flux passing through the fluorine-containing polymer is reduced, thereby avoiding the deterioration of the battery performance. According to embodiments of the disclosure, the thickness, porosity, components, and proportion of the second porous layer 26 and the first porous layer 22 can be the same or different.

According to embodiments of the disclosure, the ratio of the sum of the thickness of the first porous layer 22 and the thickness of the second porous layer 26 to the thickness of the solid electrolyte membrane 20 can be 1:5 to 4:5, such as 1:4, 1:3, 1:2, 1:1, 2:3, or 3:4.

According to embodiments of the disclosure, the electrolyte layer 24 can include a first composition. According to embodiments of the disclosure, the electrolyte layer 24 can consist of the first composition. The first composition includes: (A) 100 parts by weight of oxide-based solid state inorganic electrolyte; (B) 20 to 70 parts by weight (such as 30 parts by weight, 40 parts by weight, 50 parts by weight, or 60 parts by weight) of Li[R²(—OR¹)_n—OR²]Y, wherein R¹is C_1-4alkylene group, R²is C_1-4alkyl group, n is from 2 to 100, and Y is PF₆⁻, BF₄⁻, AsF₆⁻, SbF₆⁻, ClO₄⁻, AlCl₄⁻, GaCl₄⁻, NO₃⁻, C(SOCF₃)₃⁻, N(SO₂CF₃)₂⁻, SCN⁻, O₃SCF₂CF₃⁻, C₆F₅SO₃⁻, O₂CCF₃⁻, B(C₆H₅)₄⁻, CF₃SO₃⁻, or a combination thereof; (C) 1 to 10 parts by weight of nano-oxide; and, (D) 1 to 20 parts by weight of binder. According to embodiments of the disclosure, the components (A)-(D) of the first composition are mixed uniformly to form a composite.

According to embodiments of the disclosure, the oxide-based solid state inorganic electrolyte can be lithium-containing oxide-based solid state inorganic electrolyte, such as lithium lanthanum zirconium oxide, lithium lanthanum titanium oxide, lithium aluminum titanium phosphate, and the like, or a combination thereof.

According to embodiments of the disclosure, if the amount of Li[R²(—OR¹)_n—OR²]Y is too low, the electrolyte layer exhibits a low ionic conductivity. If the amount of Li[R²(—OR¹)_n—OR²]Y is too high, the electrolyte layer exhibits a poor mechanical strength. If n value is too low, the electrolyte layer exhibits a poor mechanical strength. If n value is too high, the electrolyte layer exhibits a low ionic conductivity at room temperature. In one embodiment, R₁is ethylene group, R₂is methyl group, n is 4, and Y is N(SO₂CF₃)₂⁻ for Li[R²(OR¹)_n—OR²]Y. Too little amount of the nano-oxide causes a low film formability of the electrolyte layer. Too much amount of the nano-oxide causes the poor ionic conductivity of the electrolyte layer. In one embodiment, the nano-oxide includes silicon oxide, aluminum oxide, cerium oxide, titanium oxide, or a combination thereof. In one embodiment, the nano-oxide has a size of 5 nm to 100 nm. Nano-oxide that is too small may not be easily dispersed in the electrolyte. Nano-oxide that is too large may result in the electrolyte having poor ionic conductivity. If the amount of the binder is too low, the electrolyte layer cannot form. The amount of the binder is too much, electrolyte layer may be hard and brittle. In one embodiment, the binder includes polyvinylidene fluoride (PVDF), polytetrafluoroethylene (PTFE), polyvinyl alcohol (PVA), polyethylene glycol (PEG), carboxymethyl cellulose (CMC), styrene butadiene rubber (SBR), polyacrylate, polyacrylonitrile (PAN), or a combination thereof.

Alternatively, the electrolyte may further includes (E) 1 to 20 parts by weight of hyper-branched polymer, and the surface of the oxide-based solid state inorganic electrolyte is modified by the hyper-branched polymer. The hyper-branched polymer may improve the organic-inorganic compatibility and enhancing the ionic conductivity a the composite electrolyte layer. If the amount of hyper-branched polymer is too much, it may result in a poor ionic conductivity of the electrolyte layer. In one embodiment, the hyper-branched polymer and the surface of the oxide-based solid state inorganic electrolyte have bondings therebetween. The hyper-branched polymer is formed by a cross-linking, reaction of a prepolymer and a basic promoter, and the prepolynier is formed by a reaction of a precursor containing a maleimide functional group and a precursor of a Lewis base. For example, the precursor containing a maleimide functional group may have a structure of

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or a combination thereof, wherein R³is —CH₂NCH₂—, —C₂H₄NHC₂H₄—, —C(O)CH₂—, —CH₂OCH₂—, —C(O)—, —O—, —S—, —S—S—, —S(O)—, —CH₂S(O)CH₂—, —(O)S(O)—, —CH₂(C₆H₄)CH₂—, —CH₂(C₆H₄)O—, —(CH₂CH(CH₃)O)—, phenylene group, biphenylene group, C_2-8alkylene group.

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Each R⁶is independently —(CH₂CH₂)O—, phenylene group, or C_2-8alkylene group. R⁴is C_2-8alkylene group, —C(O)—, —C(CH₃)₂—, —O—, —S—, —S—S—, —S(O)—, —(O)S(O)—, or —O(C₆H₄)C(CF₃)₂(C₆H₄)O—.

When m=3, R⁵is

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wherein each R⁶is independently —(CH₂CH₂CH₂)O—, phenylene group, or alkylene group. a+b+c=5 or 6, and each of a, b, and c is greater than or equal to 1. When m=4, R⁵is

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wherein each R⁶is independently —(CH₂CH₂)O—, phenylene group, or C_2-8alkylene group. When m=8, R⁵is

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Furthermore, m′ is from 2 to 5.

The precursor of Lewis base may have a structure of

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wherein Z is —SH or —NH₂, and R⁷is

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wherein a′+b′=45.

The basic promoter may have a structure of

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wherein each R⁸is independently H, alkyl group, alkenyl group, phenyl group, dimethylamino group, halogen, or —NH₂, and wherein each R⁹is independently alkyl group, alkenyl group, phenyl group, or halogen.

According to embodiments of the disclosure, alkylene group can be linear or branched alkylene group. For example, C_1-8alkylene group can be methylene group, ethylene group, propylene group, butylene group, pentylene group, hexylene group, heptylene group, octylene group, or an isomer thereof. According to embodiments of the disclosure, alkyl group can be linear or branched alkyl group. For example, C_1-8alkyl group can be methyl, ethyl, propyl, butyl, pentyl, hexyl, heptyl, octyl, or an isomer thereof.

The method for manufacturing the solid electrolyte membrane 20 can include the following steps. First, a first porous film (with a thickness T1), an electrolyte film (with a thickness T2), and a second porous film (with a thickness T3) are provided. According to embodiments of the disclosure, the method for manufacturing the electrolyte film can include the following steps. R²(—OR¹)_n—OR²is mixed with LiY to form [Li(—OR¹)_n—OR²]Y, and the nano-oxide is then added thereto for forming a quasi solid state electrolyte. The oxide-based solid state inorganic electrolyte is then added to the quasi solid. state electrolyte to be mixed, and the binder is then added thereto. As such, an organic-inorganic composite electrolyte is formed, which can be compacted into a film (composite electrolyte film). The electrolyte film can be also manufactured according to the method as disclosed in Taiwan Patent Publication No. TWI634689. Next, the electrolyte film and the second porous film is disposed on the first porous film in sequence, obtaining a lamination (i.e. a lamination represented by first porous film/electrolyte film/second porous film). Next, the lamination is subjected to a compression process, obtaining the solid electrolyte membrane 20 of the disclosure, wherein the solid electrolyte membrane 20 includes a structure represented by first porous layer 22/electrolyte layer 24/second porous layer 26. Herein, the first porous layer 22 has a thickness T1′, wherein the thickness T1′ is less than the thickness T1. For example, T1′/T1 is from about 0.05 to 0.95, such as 0.1, 0.2, 0.3, 0.4, 0.5, 0.6, 0.7, 0.8, or 0.9. The electrolyte layer 24 has a thickness T2′, wherein the thickness T2′ is less than the thickness T2. For example, T2′/T2 is from about 0.05 to 0.95, such as 0.1, 0.2, 0.3, 0.4, 0.5, 0.6, 0.7, 0.8, or 0.9; and, the second porous layer 26 has a thickness T3′, wherein the thickness T3′ is less than the thickness T3, for example, T3′/T3 is from about 0.05 to 0.95, such as 0.1, 0.2, 0.3, 0.4, 0.5, 0.6, 0.7, 0.8, or 0.9. It should be noted that an electrolyte layer with a thinner thickness (such as less than 30 μm) cannot be directly manufactured by the method as disclosed in Taiwan Patent Publication No. TWI634689. By means of the method for manufacturing the solid electrolyte membrane of the disclosure, the thickness of the electrolyte layer of the solid electrolyte membrane can be further reduced. Namely, T2′/T2 can be from 0.05 to 0.3. As a result, the purpose of thin-package battery is achieved and the energy density of the battery can be increased. According to embodiments of the disclosure, the material of the first porous film has the same definition as the material of the first porous layer; the material of the second porous film has the same definition as the material of the second porous layer; and, the material of the electrolyte film has the same definition as the material of the electrolyte layer.

According to embodiments of the disclosure, the thickness of the solid electrolyte membrane can be from 1 μm to 200 μm, such as 5 μm, 10 μm, 20 μm, 50 μm, 100 μm, 150 μm, or 180 μm. If the thickness of the solid electrolyte membrane is too high, the energy density of the battery would be deteriorated. If the thickness of the solid electrolyte membrane is too low, the cycling stability of the battery would be deteriorated. In addition, the ratio of the thickness of the electrolyte layer to the thickness of the solid electrolyte membrane can be from 1:5 to 4:5, such as 1:4, 1:3, 1:2, 2:3, or 3:4.

According to embodiments of the disclosure, the battery of the disclosure can further include a separator. FIG. 3 is a schematic view showing the battery 100 according to some embodiments of the disclosure. As shown in FIG. 3, besides the negative electrode 10, the solid electrolyte membrane 20, and the positive electrode 40, the battery 100 further includes a separator 30 disposed between the solid electrolyte membrane 20 and the positive electrode 40. According to embodiments of the disclosure, the material of the separator includes insulating material, such as polyethylene (PE), polypropylene (PP), polytetrafluoroethylene film, polyamide film, polyvinyl chloride film, poly(vinylidene fluoride) film, polyaniline film, polyimide film, non-woven fabric, polyethylene terephthalate, polystyrene (PS), cellulose, or a combination thereof. For example, the separator can be PE/PP/PE multilayer composite structure.

According to embodiments of the disclosure, the battery can further include an electrolyte liquid, and the electrolyte liquid is disposed between the positive electrode and the negative electrode. The structure stacked by the positive electrode, the separator, the solid electrolyte membrane, and the negative electrode is immersed in the electrolyte liquid. Namely, the battery is filled with the electrolyte liquid. According to some embodiments of the disclosure, the electrolyte liquid can include solvent and lithium-containing compound. According to embodiments of the disclosure, the solvent can be organic solvent, such as ester solvent, ketone solvent, carbonate solvent, ether solvent, alkane solvent, amide solvent, or a combination thereof. According to embodiments of the disclosure, the solvent can be 1,2-diethoxyethane, 1,2-dimethoxyethane, 1,2-dibutoxyethane, tetrahydrofuran, 2-methyl tetrahydrofuran, dimethylacetamide (DMAc), N-methyl-2-pyrrolidone (NMP), methyl acetate, ethyl acetate, methyl butyrate, ethyl butyrate, methyl propionate, ethyl propionate, propyl acetate (PA), γ-butyrolactone (GBL), ethylene carbonate (EC), propylene carbonate (PC), diethyl carbonate (DEC), ethylmethyl carbonate (EMC), dimethyl carbonate (DMC), vinylene carbonate, butylene carbonate, dipropyl carbonate, or a combination thereof. According to embodiments of the disclosure, the lithium-containing compound can be LiPF₆, LiClO₄, lithium bis(fluorosulfonyl)imide (LiFSI), lithium oxalyldifluoro borate (LiDFOB), LiBF₄, LiSO₃CF₃, LiN(SO₂CF₃)₂, LiN(SO₂CF₂CF₃)₂, LiAsF₆, LiSbF₆, LiAlCl₄, LiGaCl₄, LiNO₃, LiC(SO₂CF₃)₃, LiSCN, LiO₃SCF₂CF₃, LiC₆F5SO₃, LiO₂CCF₃, LiSO₃F, LiB(C₆H₅)₄, LiB(C₂O₄)₂(LiBOB), LiFePO₄, Li₇La₃Zr₂O₁₂, LiLaTi₂O₆, Li_2.9PO_3.3N_0.46, Li₃PO₄, Li_1.3Al_0.3Ti_0.7(PO₄)₃, Li_3.6Si_0.6P_0.4O₄, Li₅La₃Ta₂O₁₂, or a combination thereof. In addition, according to some embodiments of the disclosure, the electrolyte composition can include solid electrolyte. The solid electrolyte can be LiFePO₄, Li₇La₃Zr₂O₁₂, Li_2.9PO_3.3N_0.46, Li₃PO₄, Li_1.3Al_0.3Ti_0.7(PO₄)₃, Li_3.6Si_0.6P_0.4O₄, Li₅La₃Ta₂O₁₂, or a combination thereof. According to embodiments of the disclosure, the lithium-containing compound concentration of the electrolyte liquid can be from 0.5M to 5M.

According to embodiments of the disclosure, the first porous layer can further include a second composition disposed within the plurality of pores, and/or the second porous layer can further include a second composition disposed within the plurality of pores. When the second composition is further disposed within the first porous layer and/or second porous layer, the mechanical strength and ionic mobility capacity of the solid electrolyte membrane can be enhanced. The second composition has the same definition as that given for the aforementioned first composition, and the detailed description is not repeated here. According to embodiments of the disclosure, the second composition and the first composition can be the same or different.

FIG. 4 is a schematic view showing the solid electrolyte membrane 20 according to some embodiments of the disclosure. As shown in FIG. 4, the solid electrolyte membrane 20 includes the first porous layer 22, the electrolyte layer 24, and the second porous layer 26. FIG. 5 is a close-up schematic view of the region 5 in the solid electrolyte membrane 20 of the battery as shown in FIG. 4. As shown in FIG. 5, besides the polymer 21 and a plurality of pores 23, the first porous layer 22 further includes a second composition 25 disposed within the plurality of pores 23.

In the solid electrolyte membrane 20 as shown in FIG. 4, the second porous layer 26 has the same definition as that given for the first porous layer 22. Namely, besides the polymer and a plurality of pores, the second porous layer 26 further includes the second composition disposed within the plurality of pores. In the solid electrolyte membrane 20 as shown in FIG. 4, the second composition 25 is distributed among the whole first porous layer 22 and the whole second porous layer 26. According to embodiments of the disclosure, the second composition 25 can also be filled into a part of the pore 23, as shown in FIG. 5. In addition, according to some embodiments of the disclosure, the whole pore 23 can be fully filled with the second composition 25, as shown in FIG. 6.

FIG. 7 is a schematic view showing the solid electrolyte membrane 20 according to some embodiments of the disclosure. As shown in FIG. 7, the first porous layer 22 consists of a first layer 22A and a second layer 22B, and the second porous layer 26 consists of a third layer 26A and a fourth layer 26B. The solid electrolyte membrane 20 sequentially includes the first layer 22A, the second layer 22B, the electrolyte layer 24, the third layer 26A, and the fourth layer 26B. In the solid electrolyte membrane as shown in FIG. 7, the second composition is disposed within the pores of the second layer 22B and the third layer 26A, and the second composition 25 is distributed among the whole second layer 22B and the whole third layer 26A. In addition, the second composition is not disposed within the pores of the first layer 22A and the fourth layer 26B. Namely, the first layer 22A and the fourth layer 26B do not include the second composition. Namely, the first layer 22A (or the fourth layer 26B) consists of the polymer and the pores. When the first porous layer 22 (or the second porous layer 26) simultaneously includes a portion with the second composition (i.e. the second layer 22B for the first porous layer 22 or the third layer 26A for the second porous layer 26) and a portion free of the second composition (i.e. the first layer 22A for the first porous layer 22 or the forth layer 26B for the second porous layer 26), the solid electrolyte membrane exhibits not only high absorbability of electrolyte liquid but also high ionic mobility. According to embodiments of the disclosure, in the first porous layer 22, the thickness ratio of the first layer 22A to the second layer 22B can be from about 1:9 to 9:1 (such as 1:8, 1:7, 1:6, 1:5, 1:4, 1:3, 1:2, 1:1, 2:1, 3:1, 4:1, 5:1, 6:1, 7:1, or 8:1). In the second porous layer 26, the thickness ratio of the third layer 26A to the fourth layer 26B can be from about 1:9 to 9:1 (such as 1:8, 1:7, 1:6, 1:5, 1:4, 1:3, 1:2, 1:1, 2:1, 3:1, 4:1, 5:1, 6:1, 7:1, or 8:1).

Below, exemplary embodiments will be described in detail with reference to the accompanying drawings so as to be easily realized by a person having ordinary knowledge in the art. The inventive concept may be embodied in various forms without being limited to the exemplary embodiments set forth herein. Descriptions of well-known parts are omitted for clarity, and like reference numerals refer to like elements throughout.

EXAMPLES
Preparation Example 1

Tetraethylene glycol dimethyl ether (TEGDME) and lithium bis(trifluoromethylsulfonyl) imide (LiTFSI) were mixed, obtaining a mixture, wherein the molar ratio of TEGDME to LiTFSI was 1:1. Next, the mixture was mixed with silicon dioxide powder (commercially available from Degussa with a trade number of Aerosil 812), obtaining a quasi solid state electrolyte (wherein the volume ratio of the mixture to silicon di oxide powder was 1:1). Next, 60 parts by weight of Li₇La₃Zr₂O₁₂was mixed with 40 parts by weight of quasi solid state electrolyte, and then 7 parts by weight of polytetrafluoroethylene (PTFE) powder was added thereinto. After compression molding, a composite film (LLZOGS) (with a thickness of 200μm) was obtained. Next, two porous polytetrafluoroethylene (PTFE) films (commercially available from EF-Materials Industries Inc. with a trade number of EFMaflon) (with an average pore size of 0.45 μm and a thickness of 30 μm) were provided. Next, the composite film (LLZOGS) was disposed between the two porous polytetrafluoroethylene (PTFE) films (i.e. forming a lamination represented by PTFE/LLZOGS/PTFE). Next, the lamination was subjected to a compression process at 150° C., obtaining a solid electrolyte membrane (ML-LLZOGS) (with a thickness about less than or equal to 50 μm). Next, the characteristics of the composite film (LLZOGS) and the solid electrolyte membrane (ML-LLZOGS) were determined by a dynamic mechanical analysis (DMA), and the results are shown in FIG. 8. As shown in FIG. 8, in comparison with the composite film (LLZOGS), the mechanical strength of the solid electrolyte membrane (ML-LLZOGS) is greatly enhanced due to the laminated structure.

Example 1

A positive electrode was provided, wherein the positive electrode included a positive electrode active material and a positive electrode current-collecting layer. Lithium cobalt oxide (LCO) (commercially available from Hunan Reshine New Material Co., Ltd.) served as the positive electrode active material, and an aluminum foil (commercially available from C.S. Aluminium Corporation) served as the positive electrode current-collecting layer. Next, a negative electrode was provided, wherein the negative electrode included a negative electrode active material. Lithium foil (commercially available from Honjo Metal Co., Ltd.) (with a thickness of 50 μm) served as the negative electrode active material. Next, a separator (available under the trade number of Celgard 2320) was provided. Next, the negative electrode, the solid electrolyte membrane (ML-LLZOGS), the separator, and the positive electrode were placed in sequence and sealed within a coin-type cell. Next, an electrolyte liquid (including LiPF₆and solvent, wherein the solvent included ethylene carbonate (EC) and diethyl carbonate (DEC) (the volume ratio of EC to DEC was 1:1), and the concentration of LiPF₆was 1.1M) was injected into the coin-type cell, obtaining a coin-type battery (CR2032). Next, a charge/discharge test of the battery was then performed, and the results are shown in FIG. 9. The charge/discharge test was performed at room temperature under the following conditions: initial formation three cycles were 0.1C charge/0.1C discharge, following cycles were charged at 0.2C and discharge at 0.5C, and 1C=3 mA/cm². As shown in FIG. 9, the metal battery still exhibited a capacity retention percentage of about 84% after 150 charge/discharge cycles.

Example 2

A lamination consisting of a lithium foil and a copper foil (commercially available from Honjo Metal Co., Ltd.) (with a thickness of 60 μm) was provided. Next, 1 part by weight of copper fluoride, 5 parts by weight of lithium nitrate, and 94 parts by weight of 1,2-dimethoxyethane were mixed, obtaining a solution. Next, the solution was coated on the surface of the lithium foil, wherein the average loading amount of the solution disposed on the surface of the lithium foil was 5 μL/cm². After drying at room temperature, an electrode with a modified layer was obtained. Next, a separator (available under the trade number of Celgard 2320) was provided. Next, the electrode, the separator, and the electrode were placed in sequence and sealed within a coin-type cell, wherein the lithium foil of the electrode was oriented toward the separator. Next, an electrolyte liquid (including LiPF₆and solvent, wherein the solvent included ethylene carbonate (EC) and diethyl carbonate (DEC) (the volume ratio of EC to DEC was 1:1), and the concentration of LiPF₆was 1.1M) was injected into the coin-type cell, obtaining a coin-type battery (CR2032). Next, the characteristics of the obtained battery were determined by electrochemical impedance spectroscopy (EIS), and the results are shown in FIG. 10. Next, the charge and discharge cycle test of the battery was performed via a battery tester (Maccor 4000) at a constant current density of 0.5 mA/cm², a capacity of 0.5 mAh/cm²and rest for 5 minutes between each charge and discharge step for 5 cycles. As a result, a solid electrolyte interface (SEI) can be formed in the battery during charging and discharging.

Example 3

A lamination consisting of a lithium foil and a copper foil (commercially available from Honjo Metal Co., Ltd.) (with a thickness of 60 μm) was provided. Next, 2 parts by weight of maleimide (commercially available from DAIWAKASEI Industry Co. LTD with a trade number of BMI1100), 1 part by weight of copper fluoride, 5 parts by weight of lithium nitrate, and 92 parts by weight of 1,2-dimethoxyethane were mixed, obtaining a solution. Next, the solution was coated on the surface of the lithium foil, wherein the average loading amount of the solution disposed on the surface of the lithium foil was 5 μL/cm². After drying at room temperature, an electrode with a modified layer was obtained. Next, a separator (available under the trade number of Celgard 2320) was provided. Next, the electrode, the separator, and the electrode were placed in sequence and sealed within a coin-type cell, wherein the lithium foil of the electrode was oriented toward the separator. Next, an electrolyte liquid (including LiPF₆and solvent, wherein the solvent included ethylene carbonate (EC) and diethyl carbonate (DEC) (the volume ratio of EC to DEC was 1:1), and the concentration of LiPF₆was 1.1M) was injected into the coin-type cell, obtaining a coin-type battery (CR2032). Next, the characteristics of the obtained battery were determined by electrochemical impedance spectroscopy (EIS), and the results are shown in FIG. 10. Next, the charge/discharge cycle test of the battery was performed via a battery tester (Maccor 4000) at a constant current density of 0.5 mA/cm², a capacity of 0.5 mAh/cm²and rest for 5 minutes between each charge and discharge step for 5 cycles. As a result, a solid electrolyte interface (SEI) can be formed in the battery during charging and discharging.

Example 4

A lamination consisting of a lithium foil and a copper foil (commercially available from Honjo Metal Co., Ltd.) (with a thickness of 60 μm) was provided. Next, 1 part by weight of maleimide (commercially available from DAIWAKASEI Industry Co. LTD with a trade number of BMI1100), 0.5 parts by weight copper fluoride, 2.5 parts by weight of lithium nitrate, and 96 parts by weight of 1,2-dimethoxyethane were mixed, obtaining a solution. Next, the solution was coated on the surface of the lithium foil, wherein the average loading amount of the solution disposed on the surface of the lithium foil was 5 μL/cm². After drying at room temperature, an electrode with a modified layer was obtained. Next, a separator (available under the trade number of Celgard 2320) was provided. Next, the electrode, the separator, and the electrode were placed in sequence and sealed within a coin-type cell, wherein the lithium foil of the electrode was oriented toward the separator. Next, an electrolyte liquid (including LiPF₆and solvent, wherein the solvent included ethylene carbonate (EC) and diethyl carbonate (DEC) (the volume ratio of EC to DEC was 1:1), and the concentration of LiPF₆was 1.1M) was injected into the coin-type cell, obtaining a coin-type battery (CR2032). Next, the characteristics of the obtained battery were determined by electrochemical impedance spectroscopy (EIS), and the results are shown in FIG. 10. Next, the charge/discharge cycle test of the battery was performed via a battery tester (Maccor 4000) at a constant current density of 0.5 mA/cm², a capacity of 0.5 mAh/cm²and rest for 5 minutes between each charge and discharge step for 5 cycles. As a result, a solid electrolyte interface (SEI) can be formed in the battery during charging and discharging.

Comparative Example 1

A lamination consisting of a lithium foil and a copper foil (commercially available from Honjo Metal Co., Ltd.) (with a thickness of 60 μm) was provided. Next, 2 parts by weight of maleimide (commercially available from DAIWAKASEI Industry Co. LTD with a trade number of BMI1100) and 98 parts by weight of 1,2-dimethoxyethane were mixed, obtaining a solution. Next, the solution was coated on the surface of the lithium foil, wherein the average loading amount of the solution disposed on the surface of the lithium foil was 5 μL/cm². After drying at room temperature, an electrode with a modified layer was obtained. Next, a separator (available under the trade number of Celgard 2320) was provided. Next, the electrode, the separator, and the electrode were placed in sequence and sealed within a coin-type cell, wherein the lithium foil of the electrode was oriented toward the separator. Next, an electrolyte liquid (including LiPF₆and solvent, wherein the solvent included ethylene carbonate (EC) and diethyl carbonate (DEC) (the volume ratio of EC to DEC was 1:1), and the concentration of LiPF₆was 1.1M) was injected into the coin-type cell, obtaining a coin-type battery (CR2032). Next, the characteristics of the obtained battery were determined by electrochemical impedance spectroscopy (EIS), and the results are shown in FIG. 10. Next, the charge/discharge cycle test of the battery was performed via a battery tester (Maccor 4000) at a constant current density of 0.5 mA/cm², a capacity of 0.5 mAh/cm²and rest for 5 minutes between each charge and discharge step for 5 cycles. As a result, there is no stable solid electrolyte interface (SEI) formed in the battery during charging and discharging.

As shown in FIG. 10, the batteries of Examples 3 and 4 (i.e. the modified layer included maleimide, copper fluoride and lithium nitrate) exhibits a relatively low impedance. In addition, in comparison with the battery of Comparative Example 1 (i.e. the modified layer merely included maleimide), the battery of Example 2 (i.e. the modified layer included copper fluoride and lithium nitrate) also exhibits a lower impedance.

Example 5

A negative electrode active layer was provided, wherein the negative electrode active layer was a lamination consisted of a lithium foil and a copper foil (commercially available from Honjo Metal Co., Ltd.) (with a thickness of 60 μm). The lithium foil served as the negative electrode active material, and the copper foil served as the negative electrode current-collecting layer. Next, 1 part by weight of copper fluoride, 5 parts by weight of lithium nitrate, and 94 parts by weight of 1,2-dimethoxyethane were mixed, obtaining a solution. Next, the solution was coated on the lithium foil, wherein the average loading amount of the solution disposed on the surface of the lithium foil (i.e. the negative electrode active layer) was 5 μL/cm². After drying at room temperature, a negative electrode with a modified layer was obtained. A positive electrode was provided, wherein the positive electrode included a positive electrode active material and a positive electrode current-collecting layer. NMC622 (commercially available from Hunan Reshine New Material Co., Ltd.) served as the positive electrode active material, and aluminum foil (commercially available from C.S. Aluminium Corporation) served as the positive electrode current-collecting layer. Next, a separator (available under the trade number of Celgard 2320) and a solid electrolyte membrane (ML-LLZOGS) of Preparation Example 1 were provided. Next, the negative electrode, the solid electrolyte membrane, the separator, and the positive electrode were placed in sequence and sealed within a coin-type cell, wherein the lithium foil of the negative electrode was oriented toward the solid electrolyte membrane. Next, an electrolyte liquid (including LiPF₆and solvent, wherein the solvent included ethylene carbonate (EC) and diethyl carbonate (DEC) (the volume ratio of EC to DEC was 1:1), and the concentration of LiPF₆was 1.1M) was injected into the coin-type cell, obtaining a coin-type battery (CR2032). Next, the cycle test of the obtained battery was measured by a battery tester (Maccor 4000) at a charge current of 0.2C and discharge current of 0.5C, and then the capacity retention was measured . The results are shown in Table 1.

Example 6

A negative electrode active layer (commercially available from Honjo Metal Co., Ltd.) (with a thickness of 60 μm) was provided, wherein the negative electrode active layer included a negative electrode active material and a negative electrode current-collecting layer. The lithium foil served as the negative electrode active material, and the copper foil served as the negative electrode current-collecting layer. Next, 2 parts by weight of maleimide (commercially available from DAIWAKASEI Industry Co. LTD with a trade number of BMI1100), 1 part by weight of copper fluoride, 5 parts by weight of lithium nitrate, and 92 parts by weight of 1,2-dimethoxyethane were mixed, obtaining a solution. Next, the solution was coated on the lithium foil, wherein the average loading amount of the solution disposed on the surface of the lithium foil (i.e. the negative electrode active material) was 5 μL/cm². After drying at room temperature, a negative electrode with a modified layer was obtained. A positive electrode was provided, wherein the positive electrode included a positive electrode active material and a positive electrode current-collecting layer. NMC622 (commercially available from Hunan Reshine New Material Co., Ltd.) served as the positive electrode active material, and aluminum foil (commercially available from C.S. Aluminium Corporation) served as the positive electrode current-collecting layer. Next, a separator (available under the trade number of Celgard 2320) and the solid electrolyte membrane of Preparation Example 1 (ML-LLZOGS) were provided. Next, the negative electrode, the solid electrolyte membrane, the separator, and the positive electrode were placed in sequence and sealed within a coin-type cell, wherein the lithium foil of the negative electrode was oriented toward the solid electrolyte membrane. Next, an electrolyte liquid (including LiPF₆and solvent, wherein the solvent included ethylene carbonate (EC) and diethyl carbonate (DEC) (the volume ratio of EC to DEC was 1:1), and the concentration of LiPF₆was 1.1M) was injected into the coin-type cell, obtaining a coin-type battery (CR2032). Next, the cycle test of the obtained battery was measured by a battery tester (Maccor 4000) at a charge current of 0.2C and discharge current of 0.5C, and then the capacity retention was measured. The results are shown in Table 1.

Comparative Example 2

A negative electrode was provided, wherein the negative electrode active layer was a lamination consisted of a lithium foil and a copper foil (commercially available from Honjo Metal Co., Ltd.) (with a thickness of 60 μm). The lithium foil served as the negative electrode active material, and the copper foil served as the negative electrode current-collecting layer. A positive electrode was provided, wherein the positive electrode included a positive electrode active material and a positive electrode current-collecting layer. NMC622 (commercially available from Hunan Reshine New Material Co., Ltd.) served as the positive electrode active material, and aluminum foil (commercially available from C.S. Aluminium Corporation) served as the positive electrode current-collecting layer. Next, a separator (available under the trade number of Celgard 2320) was provided. Next, the negative electrode, the separator, and the positive electrode were placed in sequence and sealed within a coin-type cell. Next, an electrolyte liquid (including LiPF₆and solvent, wherein the solvent included ethylene carbonate (EC) and diethyl carbonate (DEC) (the volume ratio of EC to DEC was 1:1), and the concentration of LiPF₆was 1.1M) was injected into the coin-type cell, obtaining a coin-type battery (CR2032). Next, the cycle test of the obtained battery was measured by a battery tester (Maccor 4000) at a charge current of 0.2C and discharge current of 0.5C, and then the capacity retention was measured. The results are shown in Table 1.

Comparative Example 3

A negative electrode (commercially available from Honjo Metal Co., Ltd.) (with a thickness of 60 μm) was provided, wherein the negative electrode was a lamination consisted of a lithium foil and a copper foil. The lithium foil served as the negative electrode active material, and the copper foil served as the negative electrode current-collecting layer. A positive electrode was provided, wherein the positive electrode included a positive electrode active material and a positive electrode current-collecting layer. NMC622 (commercially available from Hunan Reshine New Material Co., Ltd.) served as the positive electrode active material, and aluminum foil (commercially available from C.S. Aluminium Corporation) served as the positive electrode current-collecting layer. Next, a separator (available under the trade number of Celgard 2320) and the solid electrolyte membrane of Preparation Example 1 (ML-LLZOGS) were provided. Next, the negative electrode, the solid electrolyte membrane, the separator, and the positive electrode were placed in sequence and sealed within a coin-type cell. Next, an electrolyte liquid (including LiPF₆and solvent, wherein the solvent included ethylene carbonate (EC) and diethyl carbonate (DEC) (the volume ratio of EC to DEC was 1:1), and the concentration of LiPF₆was 1.1M) was injected into the coin-type cell, obtaining a coin-type battery (CR2032). Next, the cycle test of the obtained battery was measured by a battery tester (Maccor 4000) at a charge current of 0.2C and discharge current of 0.5C, and then the capacity retention was measured. The results are shown in Table 1.

Comparative Example 4

A negative electrode active layer was provided, wherein the negative electrode active layer was a lamination consisted of a lithium foil and a copper foil (commercially available from Honjo Metal Co., Ltd.) (with a thickness of 60 μm). The lithium foil served as the negative electrode active material, and the copper foil served as the negative electrode current-collecting layer. Next, 1 part by weight of copper fluoride, 5 parts by weight of lithium nitrate, and 94 parts by weight of 1,2-dimethoxyethane were mixed, obtaining a solution. Next, the solution was coated on the lithium foil, wherein the average loading amount of the solution disposed on the surface of the lithium foil (i.e. the negative electrode active layer) was 5 μL/cm². After drying at room temperature, a negative electrode with a modified layer was obtained. A positive electrode was provided, wherein the positive electrode included a positive electrode active material and a positive electrode current-collecting layer. NMC622 (commercially available from Hunan Reshine New Material Co., Ltd.) served as the positive electrode active material, and aluminum foil (commercially available from C.S. Aluminium Corporation) served as the positive electrode current-collecting layer. Next, the negative electrode, the separator, and the positive electrode were placed in sequence and sealed within a coin-type cell. Next, an electrolyte liquid (including LiPF₆and solvent, wherein the solvent included ethylene carbonate (EC) and diethyl carbonate (DEC) (the volume ratio of EC to DEC was 1:1), and the concentration of LiPF₆was 1.1M) was injected into the coin-type cell, obtaining a coin-type battery (CR2032). Next, the cycle test of the obtained battery was measured by a battery tester (Maccor 4000) at a charge current of 0.2C and discharge current of 0.5C, and then the capacity retention was measured. The results are shown in Table 1.

TABLE 1

the number of the

charging/discharging

solid

cycles when capacity

electrolyte

retention lower

membrane
modified layer
than 75%

Example 5
Yes
copper fluoride/
79

lithium nitrate

Example 6
Yes
BMI1100/copper
84

fluoride/lithium

nitrate

Comparative
No
No
60

Example 2

Comparative
Yes
No
60

Example 3

Comparative
No
copper fluoride/
49

Example 4

lithium nitrate

As shown in Table 1, the capacity retention of the battery of Comparative Example 3 is similar to the capacity retention of the battery which does not employ a solid electrolyte membrane (i.e. the battery of Comparative Example 2). It means that the lifespan of the battery cannot be improved by means of the use of only solid electrolyte membrane. In addition, the capacity retention of the battery of Comparative Example 4 is even lower than that of the battery which does not employ a solid electrolyte membrane (i.e. the battery of Comparative Example 2). It means that the battery, which merely employs a negative electrode with a modified layer, may exhibit shortened lifespan. In addition, the battery, which employs the negative electrode with a modified layer and the solid electrolyte membrane of the disclosure simultaneously (i.e. the batteries of Examples 5 and 6), exhibits improved lifespan.

It will be clear that various modifications and variations can be made to the disclosed methods and materials. It is intended that the specification and examples be considered as exemplary only, with the true scope of the disclosure being indicated by the following claims and their equivalents.

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Abstract

Description

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CROSS REFERENCE TO RELATED APPLICATIONS

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