Composite negative electrode of all-solid-state battery, preparation method of composite negative electrode and all-solid-state battery

Abstract

The invention relates to a composite negative electrode of an all-solid-state battery, a preparation method of the composite negative electrode and the all-solid-state battery. The composite negative electrode comprises a nanotube lithium storage layer and a doped carbon layer which are laminated, the doped carbon layer comprises a carbon material and noble metal particles doped in the carbon material; the nanotube lithium storage layer is a nanotube array layer, the nanotube array layer comprises nanotubes and pore channels which are consistent in arrangement direction, and the pore channels comprise main pore channels in the nanotubes and auxiliary pore channels formed between the nanotubes; the placement direction of nanotubes in the nanotube array layer is perpendicular to the surface direction of the doped carbon layer. According to the composite negative electrode provided by the invention, the nanotube lithium storage layer is constructed on one side of the doped carbon layer, and through the synergistic effect of the main hole channel and the auxiliary hole channel in the nanotube lithium storage layer, a lithium storage place is provided together, so that the phenomena of volume expansion and shrinkage during lithium deposition and stripping are inhibited, and the electrochemical performance of the all-solid-state battery is improved.

Description

Technical Field

[0001] The present invention relates to the technical field of battery materials, and in particular to a composite negative electrode for an all-solid-state battery, a preparation method thereof, and an all-solid-state battery. Background Art

[0002] In today's energy storage field, the development of battery technology is crucial. With the continuous progress of technology, the limitations of traditional lithium-ion batteries have become increasingly prominent. Using organic liquids as battery electrolytes, there are many safety hazards such as internal short circuits in the battery and even explosion and combustion. In order to fundamentally solve the problems existing in traditional batteries, all-solid-state battery energy storage devices have emerged.

[0003] All-solid-state batteries use solid electrolytes that are non-flammable and non-volatile, avoiding safety hazards such as possible leakage, fire, and even explosion of liquid electrolytes. In terms of energy density, all-solid-state batteries can take into account positive and negative materials with high energy density, significantly improving the energy storage capacity of the battery and meeting the needs of electric vehicles.

[0004] Noble metal particles, such as silver particles, due to their advantages such as high conductivity, high electron mobility, and good lithium affinity, when compounded with carbon materials to form a doped carbon layer, can further improve the performance of all-solid-state batteries. The high specific surface area of carbon materials can provide a good dispersion carrier for noble metal particles, enabling noble metal particles to be evenly distributed in carbon materials, giving full play to the conductivity and affinity advantages of noble metal particles, and the presence of noble metal particles can improve the interfacial contact between carbon materials and solid electrolytes. For example, the prior art CN116457962A discloses an all-solid-state lithium secondary battery and a preparation method thereof, wherein the all-solid-state lithium secondary battery includes a positive electrode active material layer, a negative electrode active material layer, and a solid electrolyte layer disposed between the positive electrode active material layer and the negative electrode active material layer. The negative electrode active material layer includes graphitized flaky carbon nanofibers (GPCNF) and silver nanoparticles, which can improve the initial charge / discharge efficiency of all-solid-state batteries and can improve their life characteristics.

[0005] However, since the doped carbon layer does not have the ability to store lithium as a negative electrode and acts as an isolation layer between the electrolyte and lithium during the battery cycle to prevent the growth of lithium dendrites at the interface due to direct contact between lithium and the electrolyte, when the all-solid-state soft-pack battery composed of the doped carbon layer negative electrode is charged, lithium is deposited between the doped carbon layer and the current collector, causing the battery volume to expand. When discharging, when lithium metal is peeled off between the doped carbon layer and the current collector, the battery volume shrinks. This repeated expansion and contraction of the battery volume during charge and discharge causes damage to the battery structure and affects the battery life. At the same time, current soft-pack battery tests all require pressurization, which affects future industrial applications.

[0006] Therefore, providing a negative electrode for an all-solid-state battery to provide a lithium storage site during lithium deposition on the negative electrode and to achieve low-pressure or zero-pressure testing of the all-solid-state battery has become an urgent problem to be solved at present. Summary of the Invention

[0007] To solve the above technical problems, the object of the present invention is to provide a composite negative electrode for an all-solid-state battery, a preparation method thereof, and an all-solid-state battery. The composite negative electrode provided by the present invention constructs a nanotube lithium storage layer on one side of the doped carbon layer. Through the synergistic effect of the main pore channels and the secondary pore channels in the nanotube lithium storage layer, a lithium storage site is provided for lithium deposition on the negative electrode together, effectively suppressing the volume expansion and contraction phenomena during lithium deposition and stripping, and improving the electrochemical performance of the all-solid-state battery.

[0008] To achieve this purpose, the present invention adopts the following technical solutions:

[0009] In the first aspect, the present invention provides a composite negative electrode for an all-solid-state battery, and the composite negative electrode includes a nanotube lithium storage layer and a doped carbon layer arranged in a stacked manner;

[0010] The doped carbon layer includes a carbon material and noble metal particles doped in the carbon material;

[0011] The nanotube lithium storage layer is a nanotube array layer, and the nanotube array layer includes nanotubes with the same arrangement direction and pore channels. The pore channels include main pore channels inside the nanotubes and secondary pore channels formed between the nanotubes;

[0012] The placement direction of the nanotubes in the nanotube array layer is perpendicular to the surface direction of the doped carbon layer.

[0013] In the present invention, "the placement direction of the nanotubes in the nanotube array layer is perpendicular to the surface direction of the doped carbon layer" means that the surface of the doped carbon layer is perpendicular to the tube length direction of the nanotubes, that is, the surface of the doped carbon layer is perpendicular to the stacking direction of the composite negative electrode, and the tube length direction (i.e., the pore channel extension direction) of the nanotubes is parallel to the stacking direction of the composite negative electrode.

[0014] The composite negative electrode provided by the present invention constructs a nanotube array layer with a consistent arrangement direction on one side of the doped carbon layer as the lithium storage layer. The main pore channels and secondary pore channels provided in the nanotube lithium storage layer cooperate with each other. During charging, they jointly accommodate the lithium deposited on the negative electrode, effectively avoiding the volume expansion phenomenon during the lithium deposition process. During discharging, lithium is uniformly stripped from the main and secondary pore channels of the nanotube lithium storage layer, effectively avoiding the volume shrinkage phenomenon during the lithium stripping process. Thus, it effectively solves the problems of volume expansion and contraction existing in the doped carbon layer negative electrode during lithium deposition and stripping, and improves the stability of the battery negative electrode structure. In addition, the nanotube array layer constructed by the present invention on one side of the doped carbon layer can also achieve zero-pressure testing of all-solid-state soft-pack batteries, without the need to use tooling for pressurized testing, which has certain application value and is conducive to the industrial production of all-solid-state batteries.

[0015] Preferably, the nanotube array layer includes a TiO2 nanotube array layer.

[0016] The nanotube array layer provided by the present invention further adopts a TiO2 nanotube array layer. On the one hand, TiO2 nanotubes have a relatively high lithium intercalation potential, which can effectively avoid the formation of lithium dendrites and ensure the safety of the negative electrode. On the other hand, titanium dioxide nanotubes have good charge-discharge capabilities and cycle stabilities at different charge-discharge current densities.

[0017] Preferably, the porosity of the nanotube array layer is above 65%, such as 65%, 66%, 67%, 68%, 69%, 70%, 71%, 72%, 73%, 74% or 75%, etc.

[0018] Preferably, the thickness of the nanotube array layer along the lamination direction is 5 - 10 μm, such as 5.0 μm, 5.5 μm, 6.0 μm, 6.5 μm, 7.0 μm, 7.5 μm, 8.0 μm, 8.5 μm, 9.0 μm, 9.5 μm or 10.0 μm, etc.

[0019] Preferably, in the nanotube array layer, the average outer diameter of the nanotubes is 60 - 80 nm, such as 60 nm, 62 nm, 64 nm, 66 nm, 68 nm, 70 nm, 72 nm, 74 nm, 76 nm, 78 nm or 80 nm, etc., the average inner diameter is 50 - 70 nm, such as 50 nm, 52 nm, 54 nm, 56 nm, 58 nm, 60 nm, 62 nm, 64 nm, 66 nm, 68 nm or 70 nm, etc., and the average thickness of the tube wall of the nanotubes is 5 - 15 nm, such as 5 nm, 6 nm, 7 nm, 8 nm, 9 nm, 10 nm, 11 nm, 12 nm, 13 nm, 14 nm or 15 nm, etc.

[0020] In the present invention, the "average thickness of the tube wall of the nanotubes" refers to the average value of the side wall thickness of a single nanotube in a direction perpendicular to the stacking direction of the composite negative electrode.

[0021] In the present invention, by regulating the thickness of the nanotube lithium storage layer in the stacking direction, as well as the average outer diameter and average inner diameter of the nanotubes in the nanotube lithium storage layer, the average aspect ratio of the nanotube array layer can be adjusted, enabling the transmission of lithium metal during charge and discharge and providing an accommodation space for the deposition and stripping of lithium, further avoiding the damage to the negative electrode structure caused by the volume expansion and contraction of lithium metal during charge and discharge, thereby improving the electrochemical performance of the all-solid-state battery.

[0022] Preferably, in the nanotube array layer, the average pore diameter of the main pore channels is 50 - 70 nm, such as 50 nm, 52 nm, 54 nm, 56 nm, 58 nm, 60 nm, 62 nm, 64 nm, 66 nm, 68 nm or 70 nm, etc.

[0023] Preferably, in the nanotube array layer, the average size of the secondary pore channels is 6 - 20 nm, such as 6 nm, 8 nm, 10 nm, 12 nm, 14 nm, 16 nm, 18 nm or 20 nm, etc.

[0024] In the present invention, the "average size of the secondary pore channels" refers to the maximum distance between any two points on the cross-section of the secondary pore channels formed between nanotubes in a direction perpendicular to the stacking direction of the composite negative electrode layer, that is, the maximum chord length of the pore.

[0025] Preferably, the nanotube lithium storage layer further includes a base layer disposed on the surface of the nanotube array layer on the side away from the doped carbon layer.

[0026] Preferably, the surface direction of the base layer is perpendicular to the stacking direction of the composite negative electrode.

[0027] Preferably, the base layer includes titanium foil.

[0028] Preferably, the thickness of the base layer in the stacking direction is 80 - 120 μm, such as 80 μm, 85 μm, 90 μm, 95 μm, 100 μm, 105 μm, 110 μm, 115 μm or 120 μm, etc.

[0029] Preferably, based on 100 wt% of the total mass of the doped carbon layer, the mass percentage of the doped noble metal particles is 15 - 25 wt%, such as 15 wt%, 16 wt%, 17 wt%, 18 wt%, 19 wt%, 20 wt%, 21 wt%, 22 wt%, 23 wt%, 24 wt% or 25 wt%, etc.

[0030] Preferably, the doped noble metal particles include silver.

[0031] Preferably, the thickness of the doped carbon layer in the stacking direction is 50-100 μm, such as 50 μm, 55 μm, 60 μm, 65 μm, 70 μm, 75 μm, 80 μm, 85 μm, 90 μm, 95 μm or 100 μm, etc.

[0032] Preferably, in the doped carbon layer, the particle size D50 of the doped noble metal particles is 50-70 nm, such as 50 nm, 52 nm, 54 nm, 56 nm, 58 nm, 60 nm, 62 nm, 64 nm, 66 nm, 68 nm or 70 nm, etc.

[0033] Preferably, in the doped carbon layer, the particle size D50 of the carbon material is 40-65 nm, such as 40 nm, 42 nm, 44 nm, 46 nm, 48 nm, 50 nm, 52 nm, 54 nm, 56 nm, 58 nm, 60 nm, 62 nm, 64 nm or 65 nm, etc.

[0034] The doped carbon layer provided by the present invention regulates the particle sizes of the doped noble metal particles and the carbon material, which can ensure the uniformity of the carbon material and the noble metal particles, thereby improving the electrochemical performance of the all-solid-state battery.

[0035] In a second aspect, the present invention provides a method for preparing a composite negative electrode of the all-solid-state battery according to the first aspect, and the preparation method includes the following steps:

[0036] (1) Mix the carbon material and the noble metal particles with a binder and an organic solvent to obtain a mixed slurry of the doped carbon layer;

[0037] (2) Coat the mixed slurry of the doped carbon layer on the surface of the nanotube array layer, and after drying, form a nanotube lithium storage layer and a doped carbon layer stacked on each other to obtain the composite negative electrode of the all-solid-state battery;

[0038] The nanotube array layer includes nanotubes with the same arrangement direction and pore channels. The pore channels include main pore channels inside the nanotubes and secondary pore channels formed between the nanotubes; the placement direction of the nanotubes in the nanotube lithium storage layer is perpendicular to the surface direction of the doped carbon layer.

[0039] The preparation method provided by the present invention coats a mixed slurry of a doped carbon layer on the surface of a nanotube array layer to form a nanotube lithium storage layer and a doped carbon layer arranged in a stacked manner. The process method adopted is simple, the preparation process is short, and in the obtained composite negative electrode, a nanotube lithium storage layer is designed on one side of the doped carbon layer. Through the synergistic effect of the main and secondary pore channels of the nanotube lithium storage layer, the problems of volume expansion and contraction of the doped carbon layer negative electrode during the charge and discharge cycle of the battery can be solved, thereby stabilizing the structure of the composite negative electrode during the operation of the battery, and further improving the electrochemical performance of the all-solid-state battery.

[0040] Preferably, the mass ratio of the carbon material to the noble metal particles in step (1) is (75 - 85):(15 - 25), such as 75:25, 76:24, 77:23, 78:22, 79:21, 80:20, 81:19, 82:18, 83:17, 84:16 or 85:15, etc.

[0041] Preferably, the mass ratio of the binder to the organic solvent in step (1) is (0.5 - 5):(95 - 99.5), such as 0.5:99.5, 1.0:99.0, 2.0:98.0, 3.0:97.0, 4.0:96.0 or 5.0:95.0, etc.

[0042] Preferably, the total mass of the binder and the organic solvent in step (1) accounts for 80 - 90% of the total mass of the mixed slurry of the doped carbon layer, such as 80%, 82%, 84%, 86%, 88% or 90%, etc.

[0043] Preferably, the binder in step (1) includes PVDF (polyvinylidene fluoride).

[0044] Preferably, the organic solvent in step (1) includes NMP (N-methylpyrrolidone).

[0045] Preferably, the nanotube array layer in step (2) includes a TiO2 nanotube array layer.

[0046] Preferably, the specific preparation process of the TiO2 nanotube array layer includes the following steps: using a titanium foil as the anode, a counter electrode as the cathode, setting it in an electrolyte composed of ammonium fluoride - water - ethylene glycol, electrolyzing, and calcining the electrolyzed anode to obtain the TiO2 nanotube array layer.

[0047] Preferably, the thickness of the titanium foil is 80 - 120 μm, such as 80 μm, 85 μm, 90 μm, 95 μm, 100 μm, 105 μm, 110 μm, 115 μm or 120 μm, etc.

[0048] Preferably, the counter electrode includes a platinum sheet.

[0049] Preferably, the voltage of the electrolysis is 40 - 60 V, such as 40 V, 42 V, 44 V, 46 V, 48 V, 50 V, 52 V, 54 V, 56 V, 58 V or 60 V, etc.

[0050] Preferably, the time of the electrolysis is 0.5 - 2 h, such as 0.5 h, 0.6 h, 0.8 h, 1.0 h, 1.2 h, 1.4 h, 1.6 h, 1.8 h or 2.0 h, etc.

[0051] Preferably, in the electrolyte, the volume ratio of the ethylene glycol to water is (90 - 98):(2 - 10), such as 90:10, 91:9, 92:8, 93:7, 94:6, 95:5, 96:4, 97:3 or 98:2, etc.

[0052] The present invention regulates the voltage and time of the electrolysis during the preparation process of the TiO₂ nanotube array layer, as well as the volume ratio of ethylene glycol to water, can regulate the structure of the formed TiO₂ nanotube array layer, ensure the formation of the main pore channels and the secondary pore channels, and moreover, by regulating the voltage and time of the electrolysis, as well as the volume ratio of ethylene glycol to water, can also adjust the aspect ratio and average pore diameter of the main pore channels of the nanotube array layer, and can adjust the average size of the secondary pore channels.

[0053] Preferably, based on 100 wt% of the total mass of the electrolyte, the mass percentage of ammonium fluoride is 0.2 - 5 wt%, such as 0.2 wt%, 0.5 wt%, 1.0 wt%, 1.5 wt%, 2.0 wt%, 2.5 wt%, 3.0 wt%, 3.5 wt%, 4.0 wt%, 4.5 wt% or 5.0 wt%, etc.

[0054] The present invention regulates the composition content of the electrolyte during the preparation process of the TiO₂ nanotube array layer, can also further regulate the structure of the nanoarray layer, improve the structural advantages of the composite negative electrode, and further enhance the electrochemical performance in the all - solid - state battery.

[0055] Preferably, during the preparation process of the TiO₂ nanotube array layer, the calcination temperature is 400 - 500 °C, such as 400 °C, 410 °C, 420 °C, 430 °C, 440 °C, 450 °C, 460 °C, 470 °C, 480 °C, 490 °C or 500 °C, etc.

[0056] The present invention regulates the calcination temperature to obtain a TiO₂ nanotube array layer with anatase crystal form.

[0057] Preferably, during the preparation process of the TiO₂ nanotube array layer, the calcination time is 0.5 - 3 h, such as 0.5 h, 1.0 h, 1.5 h, 2.0 h, 2.5 h or 3.0 h, etc.

[0058] Preferably, the coating method described in step (2) includes any one of coating, spraying or transfer printing.

[0059] Preferably, the thickness of the coated mixed slurry in step (2) is 50-100 μm, such as 50 μm, 55 μm, 60 μm, 65 μm, 70 μm, 75 μm, 80 μm, 85 μm, 90 μm, 95 μm or 100 μm, etc.

[0060] Preferably, the drying temperature in step (2) is 80-120 °C, such as 80 °C, 85 °C, 90 °C, 95 °C, 100 °C, 105 °C, 110 °C, 115 °C or 120 °C, etc.

[0061] Preferably, the drying time in step (2) is 10-20 h, such as 10 h, 11 h, 12 h, 13 h, 14 h, 15 h, 16 h, 17 h, 18 h, 19 h or 20 h, etc.

[0062] Preferably, the drying in step (2) is carried out under vacuum conditions.

[0063] In a third aspect, the present invention provides a all-solid-state battery, which includes a solid electrolyte, and a negative electrode and a positive electrode disposed on both sides of the solid electrolyte, and the negative electrode includes the composite negative electrode as described in the first aspect.

[0064] The all-solid-state battery provided by the present invention introduces a specific composite negative electrode as the negative electrode, has excellent cycling performance, and does not require a test fixture to apply pressure during the test, and can achieve low-pressure or even zero-pressure testing of the battery, which has certain application value.

[0065] Preferably, the composite negative electrode includes a doped carbon layer, a nanotube lithium storage layer and a base layer sequentially stacked in a direction away from the solid electrolyte.

[0066] Preferably, the positive electrode active material in the positive electrode includes any one of lithium nickel cobalt manganese oxide, lithium iron phosphate, lithium manganate or lithium nickel manganate, and preferably lithium nickel cobalt manganese oxide.

[0067] Preferably, the solid electrolyte includes any one of sulfide solid electrolytes, oxide solid electrolytes or polymer solid electrolytes.

[0068] Preferably, the sulfide solid electrolyte includes Li 3.25 Ge 0.25 P 0.7 S4, Li 10 GeP2S 12or any one of Li6PS5X, where X includes any one or a combination of at least two of Cl, Br, or I.

[0069] Compared with the prior art, the present invention has at least the following beneficial effects:

[0070] (1) For the composite negative electrode provided by the present invention, a nanotube array layer with the same alignment direction of nanotubes is constructed on one side of the doped carbon layer as the lithium storage layer. The main pore channels and secondary pore channels provided in the nanotube lithium storage layer cooperate with each other. During charging, they jointly accommodate the lithium deposited on the negative electrode, effectively avoiding the problem of volume expansion of the battery during the lithium deposition process. During discharging, lithium is uniformly peeled off from the main and secondary pore channels of the nanotube lithium storage layer, effectively avoiding the problem of volume shrinkage of the battery during the lithium peeling process. Thus, it effectively solves the problems of volume expansion and contraction existing in the doped carbon layer negative electrode during lithium deposition and peeling, and improves the stability of the battery negative electrode structure. In addition, the nanotube array layer constructed on one side of the doped carbon layer of the composite negative electrode provided by the present invention can also achieve zero-pressure testing of all-solid-state soft-pack batteries, without the need to use tooling for pressure testing, which has certain application value and is conducive to the industrial production of all-solid-state batteries.

[0071] (2) The preparation method provided by the present invention coats the mixed slurry of the doped carbon layer on the surface of the nanotube array layer to form a stacked nanotube lithium storage layer and doped carbon layer. The process method used is simple, the preparation process is short, and in the obtained composite negative electrode, a nanotube lithium storage layer is designed on one side of the doped carbon layer. Through the synergistic effect of the main and secondary pore channels of the nanotube lithium storage layer, it can solve the problems of volume expansion and contraction of the doped carbon layer negative electrode during the charge and discharge cycles of the battery, thereby stabilizing the structure of the composite negative electrode during the operation of the battery, and further improving the electrochemical performance of the all-solid-state battery. Description of the Drawings

[0072] Figure 1 is a schematic cross-sectional structure diagram of the composite negative electrode provided in Examples 1-3.

[0073] Figure 2 is a scanning electron microscope image of the TiO2 nanotube array layer of the composite negative electrode provided in Example 1.

[0074] Figure 3 is a scanning electron microscope image of the TiO2 nanotube array layer of the composite negative electrode provided in Example 2.

[0075] Figure 4 is a scanning electron microscope image of the TiO2 nanotube array layer of the composite negative electrode provided in Example 3.

[0076] Figure 5 is a scanning electron microscope image of the lithium deposition on the composite negative electrode after charging at 0.2C in the all-solid-state battery provided in Application Example 1.

[0077] Figure 6 It is a schematic structural diagram of the solid electrolyte and the negative electrode during the charging process of the all-solid-state battery provided in Application Example 1.

[0078] Figure 7 It is a schematic structural diagram of the solid electrolyte and the negative electrode during the discharging process of the all-solid-state battery provided in Application Example 1.

[0079] Figure 8 It is a cycling performance graph of the all-solid-state battery provided in Application Example 1 within 100 cycles at 0.2C.

[0080] Figure 9 It is a schematic structural diagram of the solid electrolyte and the negative electrode during the charging process of the all-solid-state battery provided in Comparative Application Example 2.

[0081] Figure 10 It is a schematic structural diagram of the solid electrolyte and the negative electrode during the discharging process of the all-solid-state battery provided in Comparative Application Example 2.

[0082] Figure 11 It is a cycling performance graph of the all-solid-state battery provided in Comparative Application Example 1 within 100 cycles at 0.2C.

[0083] Figure 12 It is a cycling performance graph of the all-solid-state battery provided in Comparative Application Example 2 within 100 cycles at 0.2C.

[0084] In the figure, 1, base layer; 2, nanotube lithium storage layer; 21, main pore channel; 22, secondary pore channel; 3, doped carbon layer; 4, metallic lithium layer; 5, solid electrolyte. Specific Embodiments

[0085] The technical solutions of the present invention will be further described below in conjunction with the accompanying drawings and through specific embodiments. However, the following examples are merely simple examples of the present invention and do not represent or limit the scope of the claimed protection of the present invention. The scope of protection of the present invention is subject to the claims.

[0086] Example 1

[0087] This example provides a composite negative electrode for an all-solid-state battery, and its schematic cross-sectional structure diagram is as Figure 1 shown, including a base layer 1, a nanotube lithium storage layer 2, and a doped carbon layer 3 stacked in sequence. The doped carbon layer 3 is a silver-carbon layer, which is composed of conductive carbon black and silver-doped particles. The thickness of the doped carbon layer 3 in the stacking direction is 80 μm. Calculated based on 100 wt% of the total mass of the doped carbon layer 3, the mass percentage of the silver-doped particles is 20 wt%, the particle size D50 of the doped silver particles is 58 nm, and the particle size D50 of the conductive carbon black is 51 nm. The nanotube lithium storage layer 2 is a TiO2 nanotube array layer, and its scanning electron microscope image is asFigure 2 As shown, the TiO2 nanotube array layer includes TiO2 nanotubes and pore channels with consistent arrangement directions. Among them, the pore channels include the main pore channels 21 inside the TiO2 nanotubes and the secondary pore channels 22 formed between the TiO2 nanotubes; the placement direction of the TiO2 nanotubes in the TiO2 nanotube array layer is perpendicular to the surface direction of the doped carbon layer 3. The overall porosity of the TiO2 nanotube array layer is 65%, its thickness along the stacking direction is 7 μm, the average outer diameter of the TiO2 nanotubes is 78 nm, the average inner diameter is 56 nm, the average wall thickness of the TiO2 nanotube walls is 11 nm. In the TiO2 nanotube array layer, the average pore diameter of the main pore channels 21 is 56 nm, and the average pore diameter of the secondary pore channels 22 is 6 nm. The base layer 1 is a titanium foil, and its thickness along the stacking direction is 100 μm.

[0088] This embodiment also provides a preparation method for the above composite negative electrode, including the following steps:

[0089] S1. Mix conductive carbon black and silver particles with PVDF binder and NMP solvent according to the formulated amounts. The mass ratio of PVDF binder to NMP solvent is 1:99 to obtain a mixed slurry. The total mass of PVDF binder and NMP solvent accounts for 80% of the total mass of the mixed slurry.

[0090] S2. Use the titanium foil as the anode, the platinum sheet as the cathode, and the solution composed of ammonium fluoride - water - ethylene glycol as the electrolyte. Among them, the volume ratio of ethylene glycol to water is 98:2. Calculated based on the total mass percentage of the electrolyte being 100 wt%, the mass percentage of ammonium fluoride is 2 wt%. Set the voltage to 40 V and perform electrolysis for 1 h to obtain the electrolyzed titanium foil. Place the electrolyzed titanium foil in a muffle furnace, calcine it at 450 °C for 1 h, and cool it to 25 °C to form a TiO2 nanotube array layer on the base layer 1 of the titanium foil as the nanotube lithium storage layer 2.

[0091] S3. Coating the mixed slurry prepared in step S1 on the surface of the TiO2 nanotube array layer away from the titanium foil side by the coating method, and then placing it in a vacuum drying oven for drying at 100 °C for 15 h to obtain a silver - carbon layer as the doped carbon layer 3, forming a titanium foil, a TiO2 nanotube array layer, and a silver - carbon layer stacked in sequence to obtain the composite negative electrode.

[0092] Example 2

[0093] This embodiment provides a composite negative electrode for an all - solid - state battery, and its schematic cross - sectional structure diagram is as Figure 1As shown, it includes a base layer 1, a nanotube lithium storage layer 2, and a doped carbon layer 3 that are stacked in sequence. The doped carbon layer 3 is a silver-carbon layer, which is composed of conductive carbon black and silver-doped particles. The thickness of the doped carbon layer 3 in the stacking direction is 100 μm. Taking the total mass percentage of the doped carbon layer 3 as 100 wt%, the mass percentage of the silver-doped particles is 20 wt%. The particle size D50 of the doped silver particles is 69 nm, and the particle size D50 of the conductive carbon black is 63 nm; the nanotube lithium storage layer 2 is a TiO2 nanotube array layer, and its scanning electron microscope image is as Figure 3 shown. The TiO2 nanotube array layer includes TiO2 nanotubes and pore channels with the same arrangement direction. Among them, the pore channels include a main pore channel 21 inside the TiO2 nanotubes and a secondary pore channel 22 formed between the TiO2 nanotubes; the placement direction of the TiO2 nanotubes in the TiO2 nanotube array layer is perpendicular to the surface direction of the doped carbon layer 3. The overall porosity of the TiO2 nanotube array layer is 71%, its thickness in the stacking direction is 10 μm, the average outer diameter of the TiO2 nanotubes is 72 nm, the average inner diameter is 54 nm, and the average wall thickness of the TiO2 nanotube walls is 9 nm. In the TiO2 nanotube array layer, the average pore diameter of the main pore channel 21 is 54 nm, and the average pore diameter of the secondary pore channel 22 is 8 nm. The base layer 1 is a titanium foil, and its thickness in the stacking direction is 100 μm.

[0094] This embodiment also provides a preparation method for the above composite negative electrode, which includes the following steps:

[0095] S1. Using a titanium foil as the anode, a platinum sheet as the cathode, and a solution composed of ammonium fluoride - water - ethylene glycol as the electrolyte. Among them, the volume ratio of ethylene glycol to water is 95:5. Taking the total mass percentage of the electrolyte as 100 wt%, the mass percentage of ammonium fluoride is 5 wt%. Set the voltage to 50 V and perform electrolysis for 2 h to obtain the electrolyzed titanium foil. Place the electrolyzed titanium foil in a muffle furnace, calcine it at 500 °C for 3 h, and cool it to 25 °C to form a TiO2 nanotube array layer on the base layer 1 of the titanium foil as the nanotube lithium storage layer 2.

[0096] S2. Mix the conductive carbon black and silver particles with the PVDF binder and NMP solvent according to the formulated amounts. The mass ratio of the PVDF binder to the NMP solvent is 3:97 to obtain a mixed slurry. The total mass of the PVDF binder and the NMP solvent accounts for 85% of the total mass of the mixed slurry.

[0097] S3. On the surface of the TiO₂ nanotube array layer obtained in step S1, which is away from the titanium foil side, the mixed slurry prepared in step S2 is coated by the coating method. Then, it is placed in a vacuum drying oven for drying at 120 °C for 10 h to obtain a silver-carbon layer as the doped carbon layer 3, forming a titanium foil, a TiO₂ nanotube array layer, and a silver-carbon layer stacked in sequence to obtain a composite negative electrode.

[0098] Example 3

[0099] This example provides a composite negative electrode for an all-solid-state battery, and its cross-sectional structure schematic diagram is as Figure 1 shown, including a base layer 1, a nanotube lithium storage layer 2, and a doped carbon layer 3 stacked in sequence. The doped carbon layer 3 is a silver-carbon layer, which is composed of uniformly dispersed conductive carbon black and silver-doped particles. The thickness of the doped carbon layer 3 in the stacking direction is 50 μm. Calculated based on the total mass percentage of the doped carbon layer 3 being 100 wt%, the mass percentage of the silver-doped particles is 20 wt%, the particle size D50 of the doped silver particles is 52 nm, and the particle size D50 of the conductive carbon black is 41 nm. The nanotube lithium storage layer 2 is a TiO₂ nanotube array layer, and its scanning electron microscope image is as Figure 4 shown. The TiO₂ nanotube array layer includes TiO₂ nanotubes with the same arrangement direction and pore channels. Among them, the pore channels include a main pore channel 21 inside the TiO₂ nanotubes and a secondary pore channel 22 formed between the TiO₂ nanotubes. The placement direction of the TiO₂ nanotubes in the TiO₂ nanotube array layer is perpendicular to the surface direction of the doped carbon layer 3. The overall porosity of the TiO₂ nanotube array layer is 70%, its thickness in the stacking direction is 6 μm, the average outer diameter of the TiO₂ nanotubes is 64 nm, the average inner diameter is 50 nm, the average wall thickness of the TiO₂ nanotube walls is 7 nm. In the TiO₂ nanotube array layer, the average pore diameter of the main pore channel 21 is 50 nm, and the average pore diameter of the secondary pore channel 22 is 7 nm. The base layer is a titanium foil, and its thickness in the stacking direction is 100 μm.

[0100] This example also provides a preparation method for the above composite negative electrode, including the following steps:

[0101] S1. According to the formula amount, conductive carbon black and silver particles are mixed with a PVDF binder and an NMP solvent. The mass ratio of the PVDF binder to the NMP solvent is 5:95 to obtain a mixed slurry. The total mass of the PVDF binder and the NMP solvent accounts for 90% of the total mass of the mixed slurry.

[0102] S2. Using a titanium foil as the anode, a platinum sheet as the cathode, and a solution composed of ammonium fluoride - water - ethylene glycol as the electrolyte. Among them, the volume ratio of ethylene glycol to water is 93:7. Calculated based on 100 wt% of the total mass of the electrolyte, the mass percentage of ammonium fluoride is 0.2 wt%. Set the voltage to 60 V and perform electrolysis for 0.5 h to obtain the electrolyzed titanium foil. Place the electrolyzed titanium foil in a muffle furnace and calcine it at 400 °C for 0.5 h, then cool it to 25 °C to form a TiO2 nanotube array layer on the base layer 1 of the titanium foil as the nanotube lithium storage layer 2.

[0103] S3. Coating the mixed slurry prepared in step S1 on the surface of the TiO2 nanotube array layer away from the titanium foil side by the coating method. Then, place it in a vacuum drying oven for drying at 80 °C for 20 h to obtain a silver - carbon layer as the doped carbon layer 3, forming a titanium foil, a TiO2 nanotube array layer, and a silver - carbon layer stacked in sequence to obtain a composite negative electrode.

[0104] Example 4

[0105] The difference between this example and Example 1 is only that: in the composite negative electrode provided in this example, the thickness of the TiO2 nanotube array layer in the stacking direction is 2 μm; correspondingly, in the method for preparing the composite negative electrode provided in this example, the electrolysis time during the preparation of the TiO2 nanotube array layer is 0.4 h. The rest of the content is the same as that of Example 1.

[0106] Example 5

[0107] The difference between this example and Example 1 is only that: in the composite negative electrode provided in this example, the thickness of the TiO2 nanotube array layer in the stacking direction is 15 μm; correspondingly, in the method for preparing the composite negative electrode provided in this example, the electrolysis time during the preparation of the TiO2 nanotube array layer is 3.5 h. The rest of the content is the same as that of Example 1.

[0108] Example 6

[0109] The difference between this example and Example 1 is only that: in the composite negative electrode provided in this example, the thickness of the silver - carbon layer in the stacking direction is 40 μm. The rest of the content is the same as that of Example 1.

[0110] Example 7

[0111] The difference between this example and Example 1 is only that: in the composite negative electrode provided in this example, the thickness of the silver - carbon layer in the stacking direction is 110 μm. The rest of the content is the same as that of Example 1.

[0112] Example 8

[0113] The difference between this embodiment and Embodiment 1 is only that: in the composite negative electrode provided in this embodiment, in the TiO₂ nanotube array layer, the overall porosity is 60%. Correspondingly, in the method for preparing the composite negative electrode provided in this embodiment, the volume ratio of ethylene glycol to water during the preparation of the TiO₂ nanotube array layer is 99:1, and the electrolysis time is 0.1 h. The rest of the content is the same as that in Embodiment 1.

[0114] Embodiment 9

[0115] The difference between this embodiment and Embodiment 1 is only that: in the composite negative electrode provided in this embodiment, the TiO₂ nanotube array layer is replaced with a carbon nanotube array layer. The rest of the content is the same as that in Embodiment 1.

[0116] Embodiment 10

[0117] The difference between this embodiment and Embodiment 1 is only that: in the method for preparing the composite negative electrode provided in this embodiment, the electrolysis voltage during the preparation of the TiO₂ nanotube array layer is 30 V. The rest of the content is the same as that in Embodiment 1.

[0118] Embodiment 11

[0119] The difference between this embodiment and Embodiment 1 is only that: in the method for preparing the composite negative electrode provided in this embodiment, the electrolysis voltage during the preparation of the TiO₂ nanotube array layer is 70 V. The rest of the content is the same as that in Embodiment 1.

[0120] Comparative Example 1

[0121] The difference between this comparative example and Embodiment 1 is only that: this comparative example omits the silver-carbon layer. The rest of the content is the same as that in Embodiment 1.

[0122] Comparative Example 2

[0123] The difference between this comparative example and Embodiment 1 is only that: this comparative example omits the nanotube lithium storage layer 2 composed of the TiO₂ nanotube array layer. The rest of the content is the same as that in Embodiment 1.

[0124] Application Examples 1 - 11 and Comparative Application Examples 1 - 2

[0125] The composite anodes provided in Examples 1-11 and Comparative Examples 1-2 were used as the anode to assemble all-solid-state batteries with the cathode and solid electrolyte. Among them, the specific preparation process of the cathode electrode sheet used for the cathode: The ternary cathode material lithium nickel cobalt manganese oxide (NCM811) was used as the cathode active material, and was mixed with a conductive agent of conductive carbon black, a sulfide electrolyte (Li6PS5Cl), and a polyvinyl alcohol binder in a mass ratio of 85:2:10:3. Using NMP as the solvent, it was coated on an aluminum foil to obtain a cathode electrode sheet with a thickness of 600 μm; the specific preparation process of the solid electrolyte included: preparing an electrolyte slurry with Li6PS5Cl with a solid content of 43 wt% as the electrolyte and 5 wt% of SEBS-p-xylene binder (the solvent was p-xylene), and coating it on a PET (polyethylene terephthalate) plate with a thickness of 500 μm to obtain a solid electrolyte; the side of the cathode coated with the active material was relatively adhered to the solid electrolyte, and the silver-carbon layer in the anode was relatively adhered to the surface of the solid electrolyte away from the cathode side to obtain an all-solid-state battery.

[0126] Perform electrochemical tests under zero pressure on the all-solid-state batteries provided in Application Examples 1-11 and Comparative Application Examples 1-2. Place the battery in a test fixture without applying test pressure. The test was carried out at 0.2C in a voltage range of 2.5V - 4.25V for cyclic testing, record the discharge specific capacity and capacity retention rate after 100 cycles, and record the number of cycles with a capacity retention rate of more than 80%.

[0127] The test results are shown in Table 1.

[0128] Table 1

[0129]

[0130] It can be seen from the test results that:

[0131] (1) It can be seen from Application Example 1 to Application Example 3 that the composite anode provided by the present invention constructs a nanotube lithium storage layer on the doped carbon layer side. Through the synergistic effect of the main pore channels and secondary pore channels in the nanotube lithium storage layer, it jointly provides a lithium storage site for lithium deposition on the anode, effectively suppressing the volume expansion and contraction phenomena during lithium deposition and stripping, and improving the electrochemical performance of the all-solid-state battery.

[0132] Figure 5 Give a scanning electron microscope image of lithium deposition on the composite anode after charging at 0.2C in the all-solid-state battery provided by Application Example 1. It can be seen from the figure that lithium is deposited in the main pore channels and secondary pore channels of the nanotubes, indicating that both the main and secondary pore channels can provide a site for lithium deposition.

[0133] Figure 6 and Figure 7Schematic diagrams of the solid electrolyte and the anode during the charging and discharging processes of the all-solid-state battery provided in Application Example 1 are respectively given. It can be seen from the figures that during charging, lithium ions enter the composite anode through the solid electrolyte 5, and the doped carbon layer 3 induces the transport of metal lithium ions into the pore channels of the nanotube array layer in the nanotube lithium storage layer 2 provided between the doped carbon layer 3 and the base layer 1. Lithium metal is deposited inside the main pore channel 21 and the secondary pore channel 22 in the nanotube lithium storage layer 2 of the battery, and no volume expansion occurs in the composite anode of the battery; during discharging, the lithium deposited inside the main pore channel 21 and the secondary pore channel 22 of the nanotube array layer in the nanotube lithium storage layer 2 of the composite anode is stripped, and the doped carbon layer 3 induces the transport of metal lithium ions to the solid electrolyte 5, and then is transported to the cathode through the solid electrolyte 5. During this process, no volume shrinkage occurs in the composite anode of the battery either.

[0134] Figure 8 The cycling performance graph of the all-solid-state battery provided in Application Example 1 within 100 cycles at 0.2C is given. It can be seen from the figure that the specific capacity of the all-solid-state battery provided in Application Example 1 remains at 144 mAh / g after 100 cycles at 0.2C, and still has relatively excellent electrochemical performance.

[0135] (2) By comparing Application Example 1 with Application Examples 4 - 5, it can be seen that in the present invention, if the thickness of the TiO2 nanotube array layer along the stacking direction is too thin, it will cause the lithium storage layer to be unable to accommodate more lithium, resulting in additional lithium being deposited between the lithium storage layer and the silver-carbon layer, and the volume of the battery still changes; if the thickness of the TiO2 nanotube array layer along the stacking direction is too thick, it will cause the transport of lithium to be blocked and the diffusion rate to decrease, which is not conducive to the cycling stability of the battery.

[0136] (3) By comparing Application Example 1 with Application Examples 6 - 7, it can be seen that in the present invention, if the thickness of the silver-carbon layer along the stacking direction is too thin, it will cause the silver-carbon layer to be pierced by the electrolyte, resulting in the failure of interface contact and the easy generation of lithium dendrites at the interface; if the thickness of the silver-carbon layer along the stacking direction is too thick, it will cause the transport path of lithium to become longer and the rate to become slower, which is not conducive to the fast charge and discharge of the battery.

[0137] (4) By comparing Application Example 1 with Application Example 8, it can be seen that in the present invention, if the porosity of the TiO2 nanotube array layer is too low, it will cause the lithium storage space to become smaller, and additional lithium is deposited between the lithium storage structure layer and the silver-carbon layer, resulting in the change of the battery volume and failing to play a role in stabilizing the battery structure.

[0138] (5) By comparing Application Example 1 with Example 9, it can be seen that in the nanotube lithium storage layer of the present invention, compared with the carbon nanotube array layer, the TiO2 nanotube array layer has a higher lithium intercalation potential, which can effectively avoid the formation of lithium dendrites, ensure the safety of the anode, and has good charge and discharge capabilities and cycling stability at different charge and discharge current densities.

[0139] It can be seen from the comparison between Application Example 1 and Application Examples 10 - 11 that if the electrolysis voltage is too low during the preparation of the TiO2 nanotube array layer in the present invention, the thickness of the nanotube array layer will decrease, resulting in incomplete storage of lithium in the array layer and poor capacity retention rate; if the electrolysis voltage is too high during the preparation of the TiO2 nanotube array layer, the nanotube array layer will become thicker, accelerating the attenuation of the battery capacity.

[0140] It can be seen from the comparison between Application Example 1 and Comparative Application Examples 1 - 2 that if the nanotube lithium storage layer composed of the TiO2 nanotube array layer is omitted in the composite negative electrode provided by the present invention, the problems of volume expansion and contraction during lithium deposition and stripping cannot be effectively solved, resulting in poor electrochemical performance of the all - solid - state battery; if the silver - carbon layer is omitted, lithium metal cannot be effectively induced into the main and secondary pores of the TiO2 nanotube array layer, thus affecting the electrochemical performance of the all - solid - state battery.

[0141] Figure 9 and Figure 10 Schematic diagrams of the structure of the negative electrode of the all - solid - state battery provided by Comparative Application Example 2 during charging and discharging are respectively given. It can be seen from the figures that during charging, lithium ions enter the negative electrode through the solid electrolyte 5, and the doped carbon layer 3 in the negative electrode induces the transport of metal lithium ions between the doped carbon layer 3 and the base layer 1, forming a metal lithium layer 4 between the doped carbon layer 3 and the base layer 1, and the negative electrode of the battery undergoes volume expansion; during discharging, the lithium in the metal lithium layer 4 deposited between the doped carbon layer 3 and the base layer 1 is stripped, transported through the doped carbon layer 3 to the solid electrolyte 5, and then transported to the positive electrode through the solid electrolyte 5, and the negative electrode of the battery undergoes volume contraction.

[0142] Figure 11 and Figure 12 Cycling performance graphs of the all - solid - state batteries provided by Comparative Application Example 1 and Comparative Application Example 2 within 100 cycles at 0.2C are respectively given. It can be seen from the figures that for the all - solid - state battery provided by Comparative Application Example 1, the specific capacity only remains at 77.2 mAh / g after cycling 100 times at 0.2C, and a micro - short - circuit phenomenon begins to appear around 60 cycles; for the all - solid - state battery provided by Comparative Application Example 2, the specific capacity only remains at 123.9 mAh / g after cycling 100 times at 0.2C.

[0143] In summary, for the composite negative electrode provided by the present invention, a nanotube array layer with a consistent arrangement direction is constructed on one side of the doped carbon layer as the nanotube lithium storage layer. The main pore channels and secondary pore channels provided in the nanotube lithium storage layer cooperate with each other to jointly accommodate the lithium deposited during charging, effectively avoiding the expansion of the battery volume. During discharging, lithium is stripped from the main and secondary pore channels of the nanotube lithium storage structure, effectively avoiding the shrinkage of the battery volume and enhancing the stability of the battery structure. The presence of the nanotube lithium storage layer can effectively avoid the volume expansion and contraction problems caused by the doped carbon layer negative electrode during lithium deposition and stripping. In addition, the composite negative electrode provided by the present invention can achieve zero-pressure testing of all-solid-state soft-pack batteries without the need to use tooling for pressure testing, which is conducive to the industrial production of all-solid-state batteries.

[0144] The applicant declares that the above description is only the specific implementation manner of the present invention, but the protection scope of the present invention is not limited thereto. Those skilled in the art should understand that any changes or substitutions that can be easily conceived within the technical scope disclosed by the present invention by those skilled in the art all fall within the protection scope and the disclosure scope of the present invention.

Claims

1. A composite anode of an all-solid-state battery, characterized in that, The composite negative electrode includes a nanotube lithium storage layer and a doped carbon layer which are stacked; The doped carbon layer includes a carbon material and noble metal particles doped in the carbon material; The nanotube lithium storage layer is a nanotube array layer, and the nanotube array layer includes nanotubes with the same arrangement direction and pore channels. The pore channels include main pore channels inside the nanotubes and secondary pore channels formed between the nanotubes; The placement direction of the nanotubes in the nanotube array layer is perpendicular to the surface direction of the doped carbon layer.

2. The composite negative electrode of the all-solid-state battery according to claim 1, wherein The nanotube array layer includes a TiO2 nanotube array layer; Preferably, the porosity of the nanotube array layer is above 65%; Preferably, the thickness of the nanotube array layer in the stacking direction is 5 - 10 μm; Preferably, in the nanotube array layer, the average outer diameter of the nanotubes is 60 - 80 nm, the average inner diameter is 50 - 70 nm, and the average thickness of the tube walls of the nanotubes is 5 - 15 nm.

3. The composite negative electrode of the all-solid-state battery according to claim 1 or 2, characterized in that, In the nanotube array layer, the average pore diameter of the main pore channels is 50 - 70 nm; Preferably, in the nanotube array layer, the average size of the secondary pore channels is 6 - 20 nm.

4. The composite negative electrode of the all-solid-state battery according to any one of claims 1-3, characterized in that, The nanotube lithium storage layer further includes a base layer disposed on the surface of the nanotube array layer away from the doped carbon layer; Preferably, the base layer includes a titanium foil; Preferably, the thickness of the base layer in the stacking direction is 80 - 120 μm.

5. The composite negative electrode of the all-solid-state battery according to any one of claims 1-4, characterized in that, Based on 100 wt% of the total mass of the doped carbon layer, the mass percentage of the doped noble metal particles is 15 - 25 wt%; Preferably, the doped noble metal particles include silver.

6. The composite negative electrode of the all-solid-state battery according to any one of claims 1-5, characterized in that, The thickness of the doped carbon layer in the stacking direction is 50 - 100 μm; Preferably, in the doped carbon layer, the particle size D50 of the doped noble metal particles is 50 - 70 nm; Preferably, in the doped carbon layer, the particle size D50 of the carbon material is 40 - 65 nm.

7. A method for preparing a composite negative electrode of an all-solid-state battery according to any one of claims 1-6, characterized in that, The preparation method includes the following steps: (1) Mix the carbon material and noble metal particles with a binder and an organic solvent to obtain a mixed slurry for the doped carbon layer; (2) Coat the mixed slurry of the doped carbon layer on the surface of the nanotube array layer, and after drying, form a nanotube lithium storage layer and a doped carbon layer which are stacked to obtain the composite negative electrode of the all - solid - state battery; The nanotube array layer includes nanotubes with the same arrangement direction and pore channels. The pore channels include main pore channels inside the nanotubes and secondary pore channels formed between the nanotubes; The placement direction of the nanotubes in the nanotube lithium storage layer is perpendicular to the surface direction of the doped carbon layer.

8. The preparation method according to claim 7, characterized in that, In step (1), the mass ratio of the carbon material to the noble metal particles is (75 - 85):(15 - 25); Preferably, in step (2), the nanotube array layer includes a TiO2 nanotube array layer; Preferably, the specific preparation process of the TiO2 nanotube array layer comprises the following steps: using a titanium foil as the anode, using a counter electrode as the cathode, setting them in an electrolyte composed of ammonium fluoride - water - ethylene glycol, electrolyzing, taking the anode after electrolysis and calcining it to obtain the TiO2 nanotube array layer; Preferably, the voltage of the electrolysis is 40 - 60V; Preferably, the time of the electrolysis is 0.5 - 2h; Preferably, in the electrolyte, the volume ratio of ethylene glycol to water is (90 - 98):(2 - 10); Preferably, based on the total mass of the electrolyte being 100wt%, the mass percentage of ammonium fluoride is 0.2 - 5wt%.

9. A all-solid-state battery, characterized in that, The all - solid - state battery includes a solid electrolyte, as well as a negative electrode and a positive electrode arranged on both sides of the solid electrolyte, and the negative electrode includes the composite negative electrode according to any one of claims 1 - 6.

10. The all-solid-state battery according to claim 9, wherein The composite negative electrode includes a doped carbon layer, a nanotube lithium - storage layer, and a base layer which are sequentially stacked in a direction away from the solid electrolyte; Preferably, the positive electrode active material in the positive electrode includes any one of lithium nickel cobalt manganese oxide, lithium iron phosphate, lithium manganate, or lithium nickel manganate, and preferably lithium nickel cobalt manganese oxide; Preferably, the solid electrolyte includes any one of sulfide solid electrolytes, oxide solid electrolytes, or polymer solid electrolytes.

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