A solid electrolyte membrane, its preparation method and application

Abstract

This invention discloses a solid electrolyte membrane, its preparation method, and its applications, relating to the field of solid-state battery technology. The solid electrolyte membrane provided by this invention comprises modified halide solid electrolyte particles and a cross-linked polymer network matrix. The modified halide solid electrolyte particles have a halide solid electrolyte core coated with an aluminum-oxygen coating layer, imparting environmental stability and high-voltage electrochemical stability to the particles. The cross-linked polymer network matrix constructs a three-dimensional interconnected structure, providing flexible mechanical support and additional ion transport channels. Therefore, the solid electrolyte membrane provided by this invention possesses high conductivity, high stability, and excellent cycling performance.

Description

Technical Field

[0001] This invention relates to the field of solid-state battery technology, and more specifically, to a solid electrolyte membrane, its preparation method, and its application. Background Technology

[0002] Solid-state lithium-ion batteries are considered a core direction for next-generation energy storage technology due to their advantages such as high energy density, high safety, and long cycle life. Solid-state electrolytes are a key component of solid-state batteries, among which halide solid-state electrolytes (such as Li₂ZrCl₆, Li₃InCl₆, etc.) are particularly valuable due to their high room-temperature ionic conductivity (>10⁻⁶). -3 With its high efficiency (S / cm), good plasticity, and excellent cathode compatibility, halide solid electrolytes have attracted widespread attention. However, they face engineering challenges such as hygroscopicity, incompatibility with lithium anodes, and difficulties in film formation, which have hindered their commercialization.

[0003] Therefore, there is an urgent need to develop a composite solid electrolyte membrane technology that can simultaneously solve the problems of environmental stability, high-voltage electrochemical stability, and film-forming processability of halide solid electrolytes, and to prepare solid electrolyte membranes with high ionic conductivity, excellent interfacial stability, and good mechanical properties.

[0004] In view of this, the present invention is proposed. Summary of the Invention

[0005] The purpose of this invention is to provide a solid electrolyte membrane, its preparation method and application, aiming to achieve a comprehensive improvement in ionic conductivity, electrochemical stability, environmental stability and cycle performance.

[0006] This invention is implemented as follows: In a first aspect, the present invention provides a solid electrolyte membrane comprising modified halide solid electrolyte particles and a cross-linked polymer network matrix, wherein the modified halide solid electrolyte particles are distributed in the cross-linked polymer network matrix. Modified halide solid electrolyte particles include a halide solid electrolyte core and an aluminum-oxygen coating layer covering the surface of the halide solid electrolyte core.

[0007] In an optional embodiment, based on the total mass of the solid electrolyte membrane, the modified halide solid electrolyte particles account for 75% to 95% of the mass, and the cross-linked polymer network matrix accounts for 5% to 25% of the mass.

[0008] In an optional embodiment, the material of the halide solid electrolyte core is selected from at least one of Li2ZrCl6 and Li3InCl6; Preferably, the molar ratio of Al element in the modified halide solid electrolyte particles to metal element M in the halide solid electrolyte core is (0.02~0.15):1, more preferably (0.04~0.12):1; Preferably, the particle size D50 of the halide solid electrolyte core is 0.2 μm to 10 μm, more preferably 0.5 μm to 5 μm; even more preferably, the particle size D90 of the halide solid electrolyte core is not greater than 20 μm; the thickness of the aluminum oxide coating layer is 2 nm to 20 nm, more preferably 4 nm to 14 nm.

[0009] In an optional embodiment, the cross-linked polymer network matrix is ​​formed by cross-linking and curing a fluoropolymer, a lithium salt, and a cross-linking agent, wherein the gel mass content in the cross-linked polymer network matrix is ​​greater than or equal to 60%. Preferably, the fluoropolymer is selected from at least one of polyvinylidene fluoride-hexafluoropropylene copolymer and polyvinylidene fluoride; Preferably, the lithium salt is selected from lithium bis(trifluoromethanesulfonyl)imide and lithium bis(fluorosulfonyl)imide; Preferably, the crosslinking agent is selected from at least one of polyethylene glycol diacrylate and trimethylolpropane triacrylate.

[0010] In an optional embodiment, the aluminum oxide coating layer exhibits characteristic peaks in the Al 2p orbital range of 74.0–75.5 eV and metal-oxygen bonding characteristic peaks in the O 1s orbital range of 531.0–532.5 eV as detected by XPS. Preferably, the aluminum-oxygen coating is an amorphous coating containing lithium, aluminum, and oxygen components; the mass ratio of lithium, aluminum, and oxygen is (0.01–0.20):1:(0.60–2.10). Preferably, the solid electrolyte membrane has an ionic conductivity of not less than 0.5 mS / cm and a lithium-ion transference number of not less than 0.45 at 25°C. Preferably, the thickness of the solid electrolyte membrane is 40μm-100μm.

[0011] Secondly, the present invention provides a method for preparing a solid electrolyte membrane according to any of the foregoing embodiments, comprising: Modified halide solid electrolyte particles were prepared by hydrolyzing and condensing an aluminum source precursor to form a coating layer on the surface of halide solid electrolyte powder. A crosslinking precursor solution and modified halide solid electrolyte particles are mixed to obtain a mixed slurry, which is then used to form a film and crosslinked and cured.

[0012] In an optional embodiment, the process of preparing modified halide solid electrolyte particles includes: mixing an aluminum source precursor, an organic solvent, and halide solid electrolyte powder to obtain a precursor mixture; mixing the precursor mixture with a hydrolysis control agent to carry out hydrolysis and condensation reactions; then separating the products; and drying and heat-treating the separated products. Preferably, the aluminum source precursor is selected from at least one of aluminum isopropoxide, aluminum sec-butoxide, and triethylaluminum; Preferably, the organic solvent is selected from at least one of anhydrous ethanol, isopropanol, and tetrahydrofuran; Preferably, the hydrolysis control agent comprises water and a chelating stabilizer, wherein the chelating stabilizer is selected from at least one of acetylacetone and glacial acetic acid; the mass ratio of the hydrolysis control agent to the aluminum source precursor is (0.03-0.30):1, preferably (0.05-0.15):1; Preferably, the reaction temperature for hydrolysis and condensation is 20℃~40℃, and the reaction time is 2h-6h; Preferably, the heat treatment is carried out in an inert atmosphere, and the temperature is controlled at 150℃~350℃ for 1h~6h.

[0013] In an optional embodiment, the preparation process of the crosslinking precursor solution includes: mixing a fluoropolymer, a lithium salt, a crosslinking agent, an initiator, and an organic solvent; Preferably, the mass ratio of the fluoropolymer, lithium salt, and crosslinking agent is (0.2~0.4):(0.20~0.30):(0.02~0.08). Preferably, the initiator is selected from at least one of azobisisobutyronitrile, azobisisoheptanenitrile, benzoyl peroxide and dicumyl peroxide; Preferably, the mass ratio of the initiator to the fluoropolymer is (0.01~0.02):1.

[0014] In an optional embodiment, the film-forming and cross-linking curing process includes: applying the mixed slurry onto the substrate, then heating and curing it, controlling the curing temperature to be 60°C to 100°C, the curing time to be 2h to 12h, and then cooling and peeling off the solid electrolyte membrane.

[0015] Thirdly, the present invention provides a solid-state lithium-ion battery, comprising a solid electrolyte membrane prepared by any of the aforementioned embodiments or by any of the aforementioned preparation methods; and further comprising a positive electrode and a negative electrode, wherein the solid electrolyte membrane is disposed between the positive electrode and the negative electrode. Preferably, the positive electrode is a composite positive electrode, and the positive electrode active coating in the composite positive electrode comprises, by mass fraction, 70%–92% positive electrode active material, 5%–25% halide solid electrolyte, 0.5%–5% conductive agent, and 0.5%–5% binder; more preferably, when the positive electrode active material is NCM811, the mass percentage of the positive electrode active material is 80%–92%, and the mass percentage of the halide solid electrolyte is 5%–15%; when the positive electrode active material is lithium iron phosphate, the mass percentage of the positive electrode active material is 70%–88%, and the mass percentage of the halide solid electrolyte is 8%–25%. Preferably, the negative electrode is a lithium-indium alloy negative electrode or a metallic lithium negative electrode.

[0016] The present invention has the following beneficial effects: The solid electrolyte membrane provided by the present invention comprises modified halide solid electrolyte particles and a cross-linked polymer network matrix. The modified halide solid electrolyte particles have a halide solid electrolyte core and are coated with an aluminum oxide coating layer, which endows the particles with environmental stability and high-voltage electrochemical stability. The cross-linked polymer network matrix constructs a three-dimensional interconnected structure, providing flexible mechanical support and additional ion transport channels. Therefore, the solid electrolyte membrane provided by the present invention has high conductivity, high stability, and excellent cycling performance. Attached Figure Description

[0017] To more clearly illustrate the technical solutions of the embodiments of the present invention, the accompanying drawings used in the embodiments will be briefly introduced below. It should be understood that the following drawings only show some embodiments of the present invention and should not be regarded as a limitation on the scope. For those skilled in the art, other related drawings can be obtained based on these drawings without creative effort.

[0018] Figure 1 A schematic diagram of a solid electrolyte membrane provided in an embodiment of the present invention; Figure 2 for Figure 1 A schematic diagram of modified halide solid electrolyte particles.

[0019] 110 - Crosslinked polymer network matrix; 120 - Modified halide solid electrolyte particles; 121 - Halide solid electrolyte core; 122 - Aluminum oxide coating layer. Detailed Implementation

[0020] To make the objectives, technical solutions, and advantages of the embodiments of the present invention clearer, the technical solutions in the embodiments of the present invention will be clearly and completely described below. Where specific conditions are not specified in the embodiments, conventional conditions or conditions recommended by the manufacturer shall apply. Reagents or instruments whose manufacturers are not specified are all conventional products that can be purchased commercially.

[0021] like Figure 1 and Figure 2 As shown, the present invention provides a solid electrolyte membrane, comprising a cross-linked polymer network matrix 110 and modified halide solid electrolyte particles 120, wherein the modified halide solid electrolyte particles 120 are distributed in the cross-linked polymer network matrix 110. The modified halide solid electrolyte particles 120 include a halide solid electrolyte core 121 and an aluminum oxide coating layer 122 covering the surface of the halide solid electrolyte core 121, forming a core-shell structure.

[0022] It should be noted that the modified halide solid electrolyte particles 120 have a halide solid electrolyte core and an aluminum oxide coating layer 122 formed on the surface, which can endow the particles with environmental stability and high-voltage electrochemical stability. The cross-linked polymer network matrix 110 can construct a three-dimensional interconnected structure, providing flexible mechanical support and additional ion transport channels. Testing shows that the solid electrolyte membrane provided in this embodiment of the invention has an ionic conductivity ≥0.5 mS / cm at 25℃, a lithium-ion transference number not less than 0.45, an electrochemical window ≥4.5V, and a capacity retention rate ≥90% after 100 cycles at 0.5C, exhibiting both high conductivity, high stability, and excellent cycling performance.

[0023] In some embodiments, based on the total mass of the solid electrolyte membrane, the modified halide solid electrolyte particles 120 account for 75% to 95% of the mass, such as 75%, 80%, 85%, 90%, 95%, etc.; the crosslinked polymer network matrix 110 accounts for 5% to 25% of the mass, such as 5%, 10%, 15%, 20%, 25%, etc. By adjusting the mass ratio of the crosslinked polymer network matrix 110 and the modified halide solid electrolyte particles 120, it is beneficial to better exert the synergistic effect and improve the ionic conductivity, electrochemical stability, environmental stability, and cycle performance of the product.

[0024] In some embodiments, the material of the halide solid electrolyte core 121 is selected from at least one of Li₂ZrCl₆ and Li₃InCl₆, and the material of the halide solid electrolyte core 121 can be any one or more of the above. The molar ratio of Al element in the modified halide solid electrolyte particles 120 to metal element M in the halide solid electrolyte core 121 is (0.02~0.15):1, such as 0.02:1, 0.04:1, 0.05:1, 0.08:1, 0.10:1, 0.12:1, 0.15:1, etc., preferably (0.04~0.12):1. For halide solid electrolytes such as Li₂ZrCl₆ and Li₃InCl₆, M should be defined as skeletal metal elements such as Zr and In, but not Li.

[0025] In some embodiments, the particle size D50 of the halide solid electrolyte core 121 is 0.2 μm to 10 μm, such as 0.2 μm, 0.5 μm, 1.0 μm, 2.0 μm, 3.0 μm, 4.0 μm, 5.0 μm, 6.0 μm, 7.0 μm, 8.0 μm, 9.0 μm, 10.0 μm, etc., preferably 0.5 μm to 5 μm. The particle size D90 of the halide solid electrolyte core 121 is not greater than 20 μm. The thickness of the aluminum oxide coating layer 122 is 2 nm to 20 nm, such as 2 nm, 4 nm, 8 nm, 10 nm, 12 nm, 14 nm, 18 nm, 20 nm, etc., preferably 4 nm to 14 nm. By controlling the proportion of the coating layer in the modified halide solid electrolyte particles 120, it is beneficial to improve the ionic conductivity and cycle performance of the product while ensuring product stability.

[0026] In some embodiments, the crosslinked polymer network matrix 110 is formed by crosslinking and curing a fluoropolymer, a lithium salt, and a crosslinking agent. The gel mass content in the crosslinked polymer network matrix 110 is greater than or equal to 60%, such as 60%, 65%, 70%, 75%, 80%, 85%, 90%, etc. The fluoropolymer is selected from at least one of polyvinylidene fluoride-hexafluoropropylene copolymer and polyvinylidene fluoride, and the fluoropolymer can be any one or more of the above. The lithium salt is selected from lithium bis(trifluoromethanesulfonyl)imide and lithium bis(fluorosulfonyl)imide, and the lithium salt can be any one or more of the above. The crosslinking agent is selected from at least one of polyethylene glycol diacrylate and trimethylolpropane triacrylate, and the crosslinking agent can be any one or more of the above.

[0027] Furthermore, XPS analysis revealed characteristic peaks in the Al 2p orbital range of 74.0–75.5 eV and metal-oxygen bonding characteristic peaks in the O 1s orbital range of 531.0–532.5 eV. In a preferred embodiment, the aluminum oxide coating layer 122 is an amorphous coating layer containing lithium, aluminum, and oxygen components; the mass ratio of lithium, aluminum, and oxygen is (0.01–0.20):1:(0.60–2.10), such as 0.01:1:0.60, 0.03:1:0.80, 0.05:1:1.00, 0.08:1:1.30, 0.10:1:1.50, 0.13:1:1.70, 0.15:1:1.80, 0.18:1:2.00, 0.20:1:2.10, etc., and the coating layer is an amorphous oxide coating layer (Li). x AlO y ).

[0028] Furthermore, the thickness of the solid electrolyte membrane is 40μm-100μm, such as 40μm, 50μm, 60μm, 70μm, 80μm, 90μm, 100μm, etc.

[0029] This invention also provides a method for preparing a solid electrolyte membrane, comprising the following steps: S1. Preparation of modified halide solid electrolyte particles Hydrolysis and condensation reactions using aluminum source precursors are used to form a coating layer on the surface of halide solid electrolyte powder. A 2-20 nm thick amorphous lithium aluminate coating layer is grown in situ on the surface using a non-aqueous sol-gel method (ICP-OES detection Al / M molar ratio 0.02-0.15), which endows the particles with environmental stability and high-voltage electrochemical stability.

[0030] In some embodiments, the process for preparing modified halide solid electrolyte particles is as follows: an aluminum source precursor is dissolved in an anhydrous organic solvent to form a precursor solution; halide solid electrolyte powder is dispersed in the precursor solution to obtain a precursor mixture; the precursor mixture is then mixed with a hydrolysis control agent. The mixture undergoes controlled hydrolysis and condensation of the aluminum source precursor, forming a precursor coating layer on the surface of the halide solid electrolyte powder. The product is then separated, dried, and heat-treated to obtain modified halide solid electrolyte particles with a continuous amorphous aluminum oxide coating layer on the surface.

[0031] Further, the aluminum source precursor is selected from at least one of aluminum isopropoxide, aluminum sec-butoxide, and triethylaluminum, and the aluminum source precursor can be any one or more of the above. The anhydrous organic solvent is selected from at least one of anhydrous ethanol, isopropanol, and tetrahydrofuran, and the anhydrous organic solvent can be any one or more of the above. The hydrolysis control agent includes water and a chelating stabilizer, and the chelating stabilizer is selected from at least one of acetylacetone and glacial acetic acid. The mass ratio of the hydrolysis control agent to the aluminum source precursor is (0.03-0.30):1, such as 0.03:1, 0.05:1, 0.08:1, 0.10:1, 0.15:1, 0.20:1, 0.25:1, 0.30:1, etc., preferably (0.05-0.15):1. By adjusting the type and amount of the hydrolysis control agent, the hydrolysis and condensation reaction process can be better controlled, which is beneficial to the formation of a uniform and stable coating layer.

[0032] Furthermore, the reaction temperature for the hydrolysis and condensation reactions is 20℃~40℃, such as 20℃, 25℃, 30℃, 35℃, 40℃, etc.; the reaction time is 2h~6h, such as 2h, 3h, 4h, 5h, 6h, etc. After the hydrolysis and condensation reactions are completed, the products are separated by means of filtration, dried, and then subjected to low-temperature heat treatment. The low-temperature heat treatment is carried out in an inert atmosphere (such as Ar or N2), and the heat treatment temperature is controlled at 150℃~350℃, such as 150℃, 180℃, 200℃, 230℃, 250℃, 280℃, 300℃, 320℃, 350℃, etc.; the heat treatment time is 1h~6h, such as 1h, 2h, 3h, 4h, 5h, 6h, etc. By controlling the reaction conditions and heat treatment conditions, a continuous amorphous aluminum-oxygen coating layer is formed.

[0033] S2, film formation and cross-linking curing Fluoropolymer, lithium salt, crosslinking agent, and initiator were dissolved in an organic solvent to obtain a crosslinking precursor solution. The crosslinking precursor solution and the modified halide solid electrolyte particles obtained in S1 were mixed to obtain a mixed slurry. The mixed slurry was then formed into a film and crosslinked and cured to obtain a halide composite solid electrolyte membrane. The crosslinked polymer network, with a three-dimensional interconnected structure of fluoropolymer / lithium salt / crosslinking agent (FTIR simultaneously detected CF and COC characteristic peaks), provides flexible mechanical support and additional ion transport channels.

[0034] In some embodiments, the mass ratio of the fluoropolymer, lithium salt, and crosslinking agent is (0.2~0.4):(0.20~0.30):(0.02~0.08). The types of fluoropolymer, lithium salt, and crosslinking agent are described above in the specification and will not be repeated here. The initiator is selected from at least one of azobisisobutyronitrile, azobisisoheptanenitrile, benzoyl peroxide, and dicumyl peroxide; the initiator can be any one or more of these. The mass ratio of the initiator to the fluoropolymer is (0.01~0.02):1.

[0035] In some embodiments, the film-forming and cross-linking curing process includes: applying the mixed slurry onto a substrate, then heating and curing it, controlling the curing temperature to be 60℃~100℃, such as 60℃, 65℃, 70℃, 75℃, 80℃, 85℃, 90℃, 95℃, 100℃, etc.; the curing time is 2h~12h, such as 2h, 3h, 5h, 8h, 10h, 12h, etc. After curing is complete, the solid electrolyte membrane is cooled and peeled off.

[0036] This invention also provides a solid-state lithium-ion battery, including a solid electrolyte membrane provided in this invention, and further including a positive electrode and a negative electrode, with the solid electrolyte membrane disposed between the positive and negative electrodes. The types of positive and negative electrodes are not limited; optimization of the solid electrolyte membrane can improve the battery's cycle performance and stability.

[0037] In some embodiments, the positive electrode can be a composite positive electrode. The positive electrode active coating in the composite positive electrode, by mass fraction, comprises 70%–92% positive electrode active material, 5%–25% halide solid electrolyte, 0.5%–5% conductive agent, and 0.5%–5% binder. The positive electrode active material is NCM811 or lithium iron phosphate. Preferably, when the positive electrode active material is NCM811, the mass percentage of the positive electrode active material is 80%–92%, and the mass percentage of the halide solid electrolyte is 5%–15%; when the positive electrode active material is lithium iron phosphate, the mass percentage of the positive electrode active material is 70%–88%, and the mass percentage of the halide solid electrolyte is 8%–25%.

[0038] In some embodiments, the negative electrode is a lithium indium alloy negative electrode or a metallic lithium negative electrode.

[0039] The features and performance of the present invention will be further described in detail below with reference to embodiments.

[0040] Example 1 This embodiment provides a method for preparing a solid electrolyte membrane and a solid lithium-ion battery, the specific steps of which are as follows: (1) Non-hydrosol-gel in-situ encapsulation: The procedure was performed in a glove box filled with Ar gas. 0.25 g of aluminum isopropoxide was weighed and dissolved in 20 mL of anhydrous isopropanol. The solution was stirred at room temperature for 30 min until completely dissolved, forming a transparent precursor solution. Then, 5.00 g of 1 μm halide solid electrolyte powder Li₂ZrCl₆ was added, and the mixture was stirred continuously for 2 h to ensure uniform particle dispersion. Next, 0.026 mL of deionized water was added dropwise, along with 0.02 mL of acetylacetone as a hydrolysis control agent and coordination stabilizer. The mixture was stirred for another 4 h to allow controlled hydrolysis and condensation of the aluminum precursor, preferentially forming a continuous precursor layer on the surface of the halide particles.

[0041] After the reaction, the mixture was filtered and washed three times with anhydrous isopropanol, then vacuum dried at 60°C for 4 h. The dried powder was then heated to 250°C at a rate of 2°C / min and held for 3 h in an Ar atmosphere tube furnace to transform the precursor layer into a continuous amorphous aluminum oxide coating layer. Considering the involvement of lithium components on the particle surface during heat treatment, the coating layer preferably contains lithium aluminum oxide components. After cooling, modified halide solid electrolyte particles coated with amorphous oxide were obtained, denoted as LZC@AlOx-1. The Al / Zr molar ratio was measured to be 0.079 by ICP-OES, the coating layer thickness was observed to be approximately 8 nm by TEM, and no obvious crystalline diffraction peaks of Al2O3 or LiAlO2 were observed by XRD. The coating layer preferably contains lithium, aluminum, and oxygen components. After cooling, modified halide solid electrolyte particles with an amorphous lithium aluminum oxide coating layer were obtained, denoted as LZC@AlOx-1. XPS and TEM-EDS analysis showed that the atomic ratio of Li, Al, and O in the coating layer was approximately 0.22:1:2.10, and the equivalent mass ratio was approximately 0.06:1:1.25.

[0042] The key reaction in this stage is the dissolution and coordination of aluminum alkoxides: Al(O i Pr)3+ x· i PrOH → Al(O i Pr)3·( i PrOH) x (Solvation coordination); Subsequently, 0.026 mL of deionized water (hydrolysis control agent, water / aluminum molar ratio approximately 1.2) was added dropwise, and acetylacetone (0.02 mL) was used as a chelation stabilizer to control the hydrolysis rate. The reaction was stirred at room temperature for 4 hours. The key reaction in this stage—controlled hydrolysis-condensation: Al(O i Pr)3+ H2O → Al(O i Pr)2(OH) + i PrOH (partially hydrolyzed); 2 Al(O i Pr)2(OH) → ( i PrO)2Al-O-Al(O i Pr)2+ H2O (condensation); Meanwhile, Cl on the surface of Li2ZrCl6 - A surface anchoring reaction occurs with the aluminum alkoxide hydrolysis products, enabling the oxide precursor to nucleate and grow in situ on the particle surface: ≡Li-Cl(surface) + Al(O i Pr)2(OH) → ≡Li-O-Al(Oi Pr)2+ HCl↑ (surface bonding); After the reaction, the mixture was filtered, washed three times with anhydrous isopropanol, and dried under vacuum at 60°C for 4 hours. The dried powder was then subjected to low-temperature heat treatment in an Ar atmosphere tube furnace, where the temperature was increased to 250°C at a rate of 2°C / min and held for 3 hours to convert the precursor into an amorphous lithium aluminate coating. Al-O network + Li + (from Li2ZrCl6surface) →(250℃, Ar)→ amorphous Li x AlO

[0043] After cooling, modified halide solid electrolyte particles coated with amorphous oxide were obtained, denoted as LZC@LiAlO-1 (Al / Zr molar ratio approximately 0.08). TEM observation showed that the coating layer was approximately 8 nm thick and continuous and uniform. XRD showed no crystalline peaks in Al₂O₃ or LiAlO₂, confirming the amorphous state. ICP-OES analysis revealed an Al / Zr molar ratio of 0.079.

[0044] (2) Preparation of cross-linked polymer network precursor: Weigh 0.30 g of PVDF-HFP (polyvinylidene fluoride-hexafluoropropylene copolymer, commercially available, Mw≈455,000) and dissolve it in 3 mL of N-methylpyrrolidone (NMP). Stir at 60 °C for 2 h until completely dissolved. Add 0.25 g of LiTFSI (lithium bis(trifluoromethanesulfonyl)imide) and stir for 30 min to dissolve. Then add 0.05 g of PEGDA (polyethylene glycol diacrylate, commercially available, Mn≈600) as a crosslinking agent and 0.005 g of azobisisobutyronitrile (AIBN) as a thermal initiator, and stir at room temperature for 30 min to mix evenly.

[0045] (3) Composite film formation: 4.00 g of LZC@LiAlO-1 particles obtained in step (1) were added to the precursor solution in step (2), and stirred at 500 rpm for 1 h to uniformly disperse the particles. The resulting slurry was coated onto a polytetrafluoroethylene substrate with a thickness of 400 μm using a doctor blade. The substrate was first dried in a 60℃ oven for 2 h to remove most of the solvent, then heated to 80℃ and held for 6 h to induce thermal decomposition of AIBN to generate free radicals, causing PEGDA to undergo a crosslinking reaction and form a three-dimensional crosslinked network. After crosslinking and curing, the substrate was allowed to cool naturally and peeled off to obtain a solid electrolyte membrane with a thickness of approximately 60 μm. The modified halide particles accounted for approximately 87% of the mass of the membrane, and the crosslinked polymer network matrix accounted for approximately 13%.

[0046] (4) Battery assembly: Positive electrode preparation: NCM811 (LiNi)0.8 Co 0.1 Mn 0.1 O2), Li3InCl6 (halide electrolyte), VGCF (conductive agent), and PTFE (binder) are mixed in a mass ratio of 70:20:5:5 and rolled to form a positive electrode layer (120 μm thick), which is then laminated onto an aluminum foil current collector. The negative electrode is made of lithium-indium alloy (Li-In) with a thickness of 50 μm. In an Ar glove box, a solid electrolyte membrane is sandwiched between the positive and negative electrodes and densified under isostatic pressure of 300 MPa to assemble a coin cell solid-state battery.

[0047] Examples 2-5 (changing the Al / M molar ratio) Compared with Example 1, the amount of aluminum isopropoxide in step (1) was adjusted to 0.064 g, 0.129 g, 0.386 g, and 0.482 g, respectively, corresponding to theoretical Al / Zr molar ratios of approximately 0.02, 0.04, 0.12, and 0.15. Simultaneously, the amounts of deionized water and acetylacetone were adjusted proportionally to the amount of aluminum isopropoxide, maintaining a water / aluminum molar ratio of approximately 1.2:1 and an acetylacetone / aluminum molar ratio of approximately 0.16:1. All other conditions remained the same as in Example 1. The resulting modified particles were designated as LZC@LiAlOx-0.02, LZC@LiAlOx-0.04, LZC@LiAlOx-0.12, and LZC@LiAlOx-0.15, respectively. The measured Al / Zr molar ratios by ICP-OES were 0.021, 0.041, 0.118, and 0.148, respectively. TEM observations showed that the coating thicknesses were approximately 2 nm, 4 nm, 14 nm, and 18 nm, respectively.

[0048] Table 1: Parameters of Examples 1-5

[0049] Examples 6-7 (changing the proportion of cross-linked polymer network) Compared with Example 1, the ratio of modified halide particles to crosslinked polymer precursor in step (3) was adjusted so that the polymer network mass ratio in the membrane was 5% and 25% (the particle ratio was 95% and 75% respectively), while the other conditions remained unchanged.

[0050] Examples 8-9 (changing heat treatment temperature) Compared with Example 1, the low-temperature heat treatment temperature in step (1) was adjusted to 150℃ and 350℃ respectively, while the other conditions remained unchanged.

[0051] Example 10 (Changing the type of halide) Compared with Example 1, in step (1), the halide solid electrolyte powder was replaced with Li3InCl6 (Dv50=3μm, ionic conductivity 1.5 mS / cm), and the other conditions remained unchanged.

[0052] Example 11 (Changing the type of crosslinking agent) Compared with Example 1, in step (2), the crosslinking agent was replaced by TMPTA (trimethylolpropane triacrylate) instead of PEGDA, with the same amount and the other conditions remaining unchanged.

[0053] Comparative Example 1 (Oxide-free coating) Compared with Example 1, the sol-gel coating process in step (1) was omitted, and the uncoated Li2ZrCl6 powder was directly used to form a film with the cross-linked polymer network, while the other conditions remained unchanged.

[0054] Comparative Example 2 (Uncrosslinked polymer network) Compared with Example 1, in step (2), no crosslinking agent PEGDA and initiator AIBN are added. Instead, the modified particles are composited with a linear PVDF-HFP / LiTFSI solution to form a film, and the other conditions remain unchanged.

[0055] Comparative Example 3 (replaced with existing patent solution 1: polymer coating method, see CN115700941A) Instead of oxide coating, PVDF-HFP was dissolved in NMP (5wt%), Li₂ZrCl₆ was added, stirred, and then spray-dried (140°C) to obtain a polymer-coated halide electrolyte, which was then composited with a cross-linked polymer network to form a film. The remaining conditions were the same as in Example 1.

[0056] Comparative Example 4 (replaced with existing patent solution 2: ball milling oxide coating method, refer to CN117613368A) Instead of the sol-gel method, ball milling was used to process Li₂ZrCl₆ and Li₇La₃Zr₂O. 12 (LLZO) was placed in a ball mill jar at a mass ratio of 95:5 and ball milled at 700 rpm for 24 hours to obtain an oxide-coated halide electrolyte, which was then composited with a cross-linked polymer network to form a film. The remaining conditions were the same as in Example 1.

[0057] Comparative Example 5 (replaced with existing patented solution 3: dry mixing of short rod-shaped packing, refer to CN118572182A) Short rod-shaped Al2O3 fillers (length-to-diameter ratio 10, length 1μm) were used instead of oxide coating layers. Li2ZrCl6 and Al2O3 were dry-mixed at a mass ratio of 84:15 under low shear conditions (1000 rpm, 20℃), PVDF (1%) was added, and the mixture was rolled into a film (90℃). No cross-linked polymer network was used.

[0058] Comparative Example 6 (Al / Zr molar ratio = 0.25, exceeding the specified range) Compared to Example 1, the amount of aluminum isopropoxide in step (1) was increased to 1.60 g (theoretical Al / Zr molar ratio of approximately 0.25), while other conditions remained unchanged. The Al / Zr molar ratio was measured to be 0.243 by ICP-OES. The coating thickness was observed to be approximately 35 nm by TEM.

[0059] Comparative Example 7 (Heat treatment temperature 100℃, temperature too low) Compared to Example 1, the low-temperature heat treatment temperature in step (1) was reduced to 100°C, while the other conditions remained unchanged. At this temperature, the aluminum alkoxide precursor failed to fully condense and transform into an oxide network.

[0060] Experimental Example 1 The performance of the products prepared in the test examples and comparative examples is shown in Table 1.

[0061] Product identification and reverse testing methods: I. Sample Acquisition and Preparation (a) Fully discharge the battery to be tested to the lower cutoff voltage (2.5V) and let it stand for ≥2h; (b) Cut the outer shell along the sealing edge with ceramic scissors in an Ar glove box (H2O < 0.1 ppm, O2 < 0.1 ppm); (c) Separate the positive electrode, solid electrolyte membrane, and negative electrode layer by layer; (d) Clean the solid electrolyte membrane with dimethyl carbonate (DMC) 3 times (immerse for 30s each time with gentle shaking), vacuum dry at 60℃ for 2h, and seal it in an inert atmosphere sample bottle; (e) Scrape powder from the solid electrolyte membrane for ICP-OES, XRD, XPS, and BET tests; (f) Cut the complete membrane sheet for SEM cross-section, FTIR, EIS, and migration number tests.

[0062] II. Identification of bulk chemical composition (ICP-OES) Take 50 mg of membrane powder, digest it with aqua regia at 120℃ for 4 h, and make up to 50 mL. Perform ICP-OES testing to determine the content of Al and Zr (or In, Y, Sc, Er) elements. Judgment criterion: If the Al / M molar ratio is in the range of 0.02 to 0.15.

[0063] III. Crystal Structure Identification (XRD) Take the film powder, Cu Kα radiation, scan range 10°~80° (2θ), step size 0.02°, speed 2° / min. Judgment criteria: (1) The halide main phase diffraction peaks are intact (Li2ZrCl6 triclinic phase or Li3InCl6 monoclinic phase); (2) No Al2O3 (PDF#46-1212) or γ-LiAlO2 (PDF#38-1006) crystalline peaks in the range of 2θ=20°~30° - confirming that the coating layer is amorphous.

[0064] IV. Microstructure Identification (TEM-EDS) TEM thin sections (including particle cross-sections) were prepared using FIB and observed by HRTEM at an accelerating voltage of 200 kV. Judgment criteria: a continuous amorphous coating layer of 2–20 nm thickness was visible on the particle surface; no obvious lattice fringes were observed in HRTEM (distinguishing it from crystalline oxide coatings); EDS line scanning showed that Al elements were enriched on the surface and decreased towards the core.

[0065] V. Surface Chemical Identification (XPS) Monochromatic Al Kα source (1486.6 eV), narrow scan with a pass energy of 20 eV, C 1s = 284.8 eV correction. Inert atmosphere transfer. Judgment criteria: (1) Al 2p peaks in the range of 74.0 to 75.5 eV (corresponding to amorphous Li x AlO (2) O 1s has a peak at 531.0~532.5 eV (metal-oxygen bonding).

[0066] VI. Surface Functional Group Identification (FTIR) ATR mode, diamond crystal, 4000-400 cm -1 4 cm resolution -1 32 scans. Judgment criteria: (1) 1170±10 cm -1 There is a CF stretching peak (corresponding to PVDF-HFP fluorinated polymer); (2) 1090±10 cm -1 COC ether bond peaks are present (corresponding to PEGDA crosslinking network); (3) 1340~1360 cm -1 There is an S=O peak (corresponding to LiTFSI lithium salt).

[0067] VII. Morphology and Specific Surface Area Identification (SEM / BET) SEM (5-15 kV, sputtering for 60 s) was used to observe particle morphology and film cross-section. Judgment criteria: particles are spherical or irregularly shaped, with smooth surfaces (distinguishing them from the fragmented morphology observed in ball milling), and a particle size D... 50Within the range of 0.5–10 μm. BET (N₂ adsorption, 77 K, degassing 200 °C / 4 h): specific surface area 5–30 m². 2 / g.

[0068] 8. Identification of cross-linked networks (gel content) Dry the membrane to a constant weight W0, immerse it in NMP at 60℃ for 72 hours (changing the solution every 24 hours), and then remove and dry to a constant weight W1. Gel content (%) = W1 / W0 × 100%. Judgment criterion: Gel content ≥ 60%. If gel content < 30%, it is considered an insufficiently cross-linked or uncross-linked system.

[0069] IX. Electrochemical Performance Verification (1) Ionic conductivity: SS|membrane|SS symmetric cell EIS (10 6 ~10 -2 Hz, 10 mV, 25℃), σ=L / (Rb×A)≥0.5 mS / cm. (2) Migration number: Li|film|Li symmetric cell Bruce-Vincent method (ΔV=10 mV), t Li + ≥0.45. (3) Electrochemical window: SS|membrane|Li, 1 mV / s scan, decomposition voltage ≥4.5V. (4) Full cell: 0.1C first-cycle discharge specific capacity ≥180 mAh / g; 0.5C 100-cycle capacity retention ≥90%.

[0070] Table 2: Summary of performance data for each embodiment and comparative example

[0071] Note: σ is the ionic conductivity at 25℃; t Li + Lithium-ion transference number; window is the electrochemical window (vs Li / Li). + The initial capacity is the discharge specific capacity at 0.1C; the 100-cycle retention rate is the capacity retention rate after 100 cycles at 0.5C; the rate performance is the capacity ratio of 1C / 0.1C; and the environmental stability is the conductivity retention rate after 24 hours of exposure at 30% relative humidity.

[0072] (a) Al / M molar ratio (Examples 1-5 and Comparative Example 6) As can be seen from Examples 2-5 and Example 1 in Table 2, as the Al / Zr molar ratio increases from 0.02 to 0.15, the ionic conductivity first increases and then decreases (0.72→0.70→0.68→0.58→0.51 mS / cm), while the electrochemical window and environmental stability continue to improve (4.50→4.80V, 72%→95%). The overall performance is optimal in the Al / Zr molar ratio range of 0.04 to 0.12.

[0073] The microscopic mechanism is as follows: the Al / Zr molar ratio directly determines the thickness and density of the amorphous oxide coating. When the Al / Zr molar ratio is ~0.02, the coating is too thin (<2nm), unable to form a continuous coverage, and water molecules can still penetrate the halide lattice through defect channels, causing deliquescence, resulting in an environmental stability of only 72%. Simultaneously, the thin coating has limited shielding effect on the high potential on the positive electrode side, with an electrochemical window of only 4.50V. When the Al / Zr molar ratio is higher than 0.15, the coating thickness increases to >18nm, and the amorphous Li... x AlO intrinsic ionic conductivity (approximately 10) -5 The S / cm ratio is on the order of [scale], which is much lower than that of halide phases (approximately 10). -3 The excessively thick coating layer creates a high-resistance transport bottleneck, causing the total ionic conductivity to drop to 0.51 mS / cm. Although environmental and electrochemical stability continue to improve, capacity and rate performance are limited. Within the preferred range (Al / Zr = 0.04–0.12), a coating layer thickness of 4–14 nm ensures continuous coverage for stability without excessively hindering ion transport, achieving the optimal balance between conductivity and stability.

[0074] Comparative Example 6 (Al / Zr=0.25) further confirms that the excessively thick coating layer (approximately 35 nm) causes the ionic conductivity to plummet to 0.28 mS / cm, resulting in a first-week capacity of only 152 mAh / g and a rate performance drop to 60.1%. The root cause lies in the fact that lithium ions in the thick oxide layer must undergo a long amorphous diffusion path, significantly increasing the transport resistance.

[0075] (ii) Proportion of cross-linked polymer network (Examples 1, 6, 7) As can be seen from Examples 1 (13%), 6 (5%), and 7 (25%), as the polymer content increases from 5% to 25%, the ionic conductivity decreases from 0.55 to 0.42 mS / cm, the lithium-ion transference number increases from 0.46 to 0.58, and the cycle stability increases from 89.5% to 95.5%. The overall performance is optimal when the polymer content is approximately 13%.

[0076] The microscopic mechanism is as follows: when the polymer network content is too low (5%), there is insufficient polymer interconnection between particles, resulting in poor mechanical integrity. During cycling, the membrane material is easily broken and particles fall off, leading to a continuous increase in interfacial impedance and rapid capacity decay (retention rate is only 89.5%). When the content is too high (25%), the intrinsic ionic conductivity of PVDF-HFP / LiTFSI (approximately 10) decreases. -4The high conductivity contribution of the halide phase was significantly diluted (on the order of S / cm), reducing the total conductivity to 0.42 mS / cm. Within the preferred range (10–15%), the cross-linked network provides sufficient interparticle bonding and flexible support without excessively hindering the rapid lithium-ion transport of the halide phase.

[0077] (III) Heat treatment temperature (Examples 1, 8, 9 and Comparative Example 7) Examples 1 (250℃), 8 (150℃), and 9 (350℃) show that heat treatment temperature significantly affects the coating quality. At 150℃, the aluminum alkoxide precursor condensation is incomplete, and residual organic groups reduce the density of the coating (environmental stability is only 80%). At 350℃, excessive heat treatment may lead to trace lattice rearrangement on the halide surface and local crystallization of the coating, resulting in a slight decrease in ionic conductivity (0.55 mS / cm) but an increase in stability (91%). 250℃ is the optimal equilibrium point (conductivity 0.68 mS / cm, environmental stability 88%).

[0078] Comparative Example 7 (100℃) confirmed that at excessively low temperatures, the precursor hardly transformed into an oxide network, and a large number of residual isopropoxy groups could be observed at 2850-2960 cm⁻¹ via FTIR. -1 The strong CH stretching peak indicates that the coating layer is not dense, and the environmental stability drops sharply to 52%.

[0079] (iv) Comparative Analysis Comparing Comparative Example 1 (without oxide coating) with Example 1, after removing the oxide coating, the electrochemical window decreased from 4.65V to 4.30V, the environmental stability decreased from 88% to 35%, and the 100-cycle retention rate decreased from 93.2% to 78.5%. The root cause is that the uncoated halide particles are directly exposed to the high-potential positive electrode and trace moisture environment, resulting in irreversible surface decomposition and deliquescence, and a continuous increase in interfacial impedance.

[0080] By comparing Comparative Example 2 (without crosslinked network) with Example 1, the migration number decreased from 0.52 to 0.38 without crosslinked network, and the 100-cycle retention rate decreased from 93.2% to 75.2%. The linear polymer exhibits flow creep during cycling and cannot maintain stable interparticle connections and membrane structural integrity.

[0081] By comparing Comparative Example 3 (polymer coating method) with Example 1, it can be seen that although simple polymer coating can prevent moisture to a certain extent (stability 88% vs 65% of Comparative Example 3), its high voltage resistance is far inferior to that of oxide coating (window 4.35V vs 4.65V), and interface decomposition is prone to occur during high voltage positive electrode matching.

[0082] By comparing Comparative Example 4 (ball milling oxide coating method) with Example 1, the ball milling method resulted in a significant decrease in ionic conductivity (0.38 mS / cm). The root cause was that the high-energy ball milling at 700 rpm destroyed the triclinic crystal phase structure of Li2ZrCl6 (XRD showed that the main peak broadened and the intensity decreased). At the same time, the coating layer obtained by ball milling was uneven (TEM showed that the thickness fluctuated from 5 to 80 nm).

[0083] By comparing Comparative Example 5 (short rod packing method) with Example 1, the ionic conductivity of the packing type scheme is only 0.35 mS / cm (the lowest), because the oxide packing and halide particles are only in physical contact, there is a large transmission impedance at the interface, and the packing itself occupies the effective ion transmission space.

[0084] In summary, this invention achieves a comprehensive improvement in ionic conductivity, electrochemical stability, environmental stability, and cycle performance within a range of Al / Zr molar ratio of 0.02–0.15, polymer content of 5%–25%, and heat treatment temperature of 150–350°C through the synergistic combination of non-aqueous sol-gel in-situ oxide coating, cross-linked polymer network interconnection, and reasonable process parameter control. Deviations from the range defined by this invention result in a significant decrease in performance.

[0085] The above description is merely a preferred embodiment of the present invention and is not intended to limit the invention. Various modifications and variations can be made to the present invention by those skilled in the art. Any modifications, equivalent substitutions, improvements, etc., made within the spirit and principles of the present invention should be included within the scope of protection of the present invention.

Claims

1. A solid electrolyte membrane, characterized in that, It includes modified halide solid electrolyte particles and a cross-linked polymer network matrix, wherein the modified halide solid electrolyte particles are distributed in the cross-linked polymer network matrix; The modified halide solid electrolyte particles include a halide solid electrolyte core and an aluminum-oxygen coating layer covering the surface of the halide solid electrolyte core.

2. The solid electrolyte membrane according to claim 1, characterized in that, Based on the total mass of the solid electrolyte membrane, the modified halide solid electrolyte particles account for 75% to 95% of the mass, and the cross-linked polymer network matrix accounts for 5% to 25% of the mass.

3. The solid electrolyte membrane according to claim 1 or 2, characterized in that, The material of the halide solid electrolyte core is selected from at least one of Li2ZrCl6 and Li3InCl6; Preferably, the molar ratio of Al element in the modified halide solid electrolyte particles to metal element M in the halide solid electrolyte core is (0.02~0.15):1, more preferably (0.04~0.12):1; Preferably, the particle size D50 of the halide solid electrolyte core is 0.2 μm to 10 μm, more preferably 0.5 μm to 5 μm; even more preferably, the particle size D90 of the halide solid electrolyte core is not greater than 20 μm; the thickness of the aluminum oxide coating layer is 2 nm to 20 nm, more preferably 4 nm to 14 nm.

4. The solid electrolyte membrane according to claim 1 or 2, characterized in that, The cross-linked polymer network matrix is ​​formed by cross-linking and curing of a fluoropolymer, a lithium salt, and a cross-linking agent, and the gel mass content in the cross-linked polymer network matrix is ​​greater than or equal to 60%. Preferably, the fluoropolymer is selected from at least one of polyvinylidene fluoride-hexafluoropropylene copolymer and polyvinylidene fluoride; Preferably, the lithium salt is selected from lithium bis(trifluoromethanesulfonyl)imide and lithium bis(fluorosulfonyl)imide; Preferably, the crosslinking agent is selected from at least one of polyethylene glycol diacrylate and trimethylolpropane triacrylate.

5. The solid electrolyte membrane according to claim 1, characterized in that, The aluminum-oxygen coating layer, as detected by XPS, exhibits characteristic peaks in the Al 2p orbital range of 74.0–75.5 eV and metal-oxygen bonding characteristic peaks in the O 1s orbital range of 531.0–532.5 eV. Preferably, the aluminum-oxygen coating is an amorphous coating containing lithium, aluminum, and oxygen components; the mass ratio of lithium, aluminum, and oxygen is (0.01–0.20):1:(0.60–2.10). Preferably, the solid electrolyte membrane has an ionic conductivity of not less than 0.5 mS / cm and a lithium-ion transference number of not less than 0.45 at 25°C. Preferably, the thickness of the solid electrolyte membrane is 40μm-100μm.

6. A method for preparing a solid electrolyte membrane according to any one of claims 1-5, characterized in that, include: Modified halide solid electrolyte particles were prepared by hydrolyzing and condensing an aluminum source precursor to form a coating layer on the surface of halide solid electrolyte powder. A crosslinking precursor solution and modified halide solid electrolyte particles are mixed to obtain a mixed slurry, which is then used to form a film and crosslinked and cured.

7. The preparation method according to claim 6, characterized in that, The process for preparing the modified halide solid electrolyte particles includes: mixing an aluminum source precursor, an organic solvent, and halide solid electrolyte powder to obtain a precursor mixture; mixing the precursor mixture with a hydrolysis control agent to carry out hydrolysis and condensation reactions; then separating the products; and drying and heat-treating the separated products. Preferably, the aluminum source precursor is selected from at least one of aluminum isopropoxide, aluminum sec-butoxide, and triethylaluminum; Preferably, the organic solvent is selected from at least one of anhydrous ethanol, isopropanol, and tetrahydrofuran; Preferably, the hydrolysis control agent comprises water and a chelating stabilizer, wherein the chelating stabilizer is selected from at least one of acetylacetone and glacial acetic acid; the mass ratio of the hydrolysis control agent to the aluminum source precursor is (0.03-0.30):1, preferably (0.05-0.15):1; Preferably, the reaction temperature for hydrolysis and condensation is 20℃~40℃, and the reaction time is 2h-6h; Preferably, the heat treatment is carried out in an inert atmosphere, and the temperature is controlled at 150℃~350℃ for 1h~6h.

8. The preparation method according to claim 6, characterized in that, The preparation process of the crosslinking precursor solution includes: mixing a fluoropolymer, a lithium salt, a crosslinking agent, an initiator, and an organic solvent; Preferably, the mass ratio of the fluoropolymer, the lithium salt, and the crosslinking agent is (0.2~0.4):(0.20~0.30):(0.02~0.08). Preferably, the initiator is selected from at least one of azobisisobutyronitrile, azobisisoheptanenitrile, benzoyl peroxide, and dicumyl peroxide; Preferably, the mass ratio of the initiator to the fluoropolymer is (0.01~0.02):

1.

9. The preparation method according to claim 6, characterized in that, The process of film formation and cross-linking curing includes: applying the mixed slurry onto the substrate, then heating and curing, controlling the curing temperature to be 60℃~100℃, the curing time to be 2h~12h, and then cooling and peeling off the solid electrolyte membrane.

10. A solid-state lithium-ion battery, characterized in that, Includes the solid electrolyte membrane according to any one of claims 1-5 or the solid electrolyte membrane prepared by the preparation method according to any one of claims 6-9; further includes a positive electrode and a negative electrode, wherein the solid electrolyte membrane is disposed between the positive electrode and the negative electrode; Preferably, the positive electrode is a composite positive electrode, and the positive electrode active coating in the composite positive electrode comprises, by mass fraction, 70%–92% positive electrode active material, 5%–25% halide solid electrolyte, 0.5%–5% conductive agent, and 0.5%–5% binder; more preferably, when the positive electrode active material is NCM811, the mass percentage of the positive electrode active material is 80%–92%, and the mass percentage of the halide solid electrolyte is 5%–15%; when the positive electrode active material is lithium iron phosphate, the mass percentage of the positive electrode active material is 70%–88%, and the mass percentage of the halide solid electrolyte is 8%–25%. Preferably, the negative electrode is a lithium indium alloy negative electrode or a metallic lithium negative electrode.

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