All-solid-state battery and preparation method and application thereof

Abstract

The invention discloses an all-solid-state battery and a preparation method and application thereof, and relates to the technical field of solid-state batteries. According to the all-solid-state battery provided by the invention, the halide and the oxyhalide with certain electrochemical activity are adopted as the solid electrolyte, and the specific capacity of the obtained battery is greatly improved by limiting the volume ratio of the electrolyte to the positive electrode layer and performing interface engineering regulation and control on the interface between the electrolyte and the positive electrode layer; the specific discharge capacity can reach more than 312 mAh / g according to the mass of the positive electrode active material, the specific discharge capacity can reach more than 202 mAh / g according to the total mass of the positive electrode, and the capacity of the battery can be effectively improved on the premise of not increasing the thickness of the battery assembly and the battery, so that the energy density of the all-solid-state battery is improved.

Description

TECHNICAL FIELD

[0001] The present application relates to the technical field of solid-state batteries, in particular to a full solid-state battery and a preparation method and application thereof. BACKGROUND

[0002] With the increasing demand for high energy density and high safety energy storage devices in the electric vehicle and portable electronic device industries, full solid-state batteries are considered as the core direction of the next generation of battery technology because their theoretical energy density can reach more than 500 Wh / kg and they use safe solid-state electrolytes instead of flammable organic liquid electrolytes. However, the actual energy density of existing full solid-state batteries is generally less than 300 Wh / kg, which is much lower than expected. The main factors that determine the energy density of solid-state batteries include the intrinsic properties of the electrode active material, the intrinsic properties of the electrolyte material, and the interface properties of the two.

[0003] The structure of the existing full solid-state battery is in the form of a "sandwich", which is composed of a positive electrode material, a solid-state electrolyte and a negative electrode material. However, due to the low ion conductivity of traditional positive electrode materials and the weak wetting effect between the solid-state electrolyte and the positive electrode material, the positive electrode material needs to be mixed with a large amount of solid-state electrolyte in advance to ensure that the resulting composite positive electrode has sufficient electronic conductivity and ionic conductivity before the solid-state battery is assembled. However, the solid-state electrolyte is usually a non-active substance, which leads to a dilution of the concentration of the positive electrode active material in the composite positive electrode and a significant reduction in the loading capacity, making it impossible to achieve a high energy density full solid-state battery. SUMMARY

[0004] In order to solve the problems of the prior art, the present application aims to provide a full solid-state battery with significantly improved specific capacity through interface engineering regulation. The present application also provides a preparation method of the full solid-state battery and an application of the full solid-state battery.

[0005] The above-mentioned object of the present application is achieved by the following technical solutions: A full solid-state battery, comprising a composite positive electrode and a negative electrode, the composite positive electrode comprising a positive electrode material layer and an electrolyte layer, the preparation raw material of the electrolyte layer comprising an active electrolyte, the active electrolyte comprising at least one of an active halide electrolyte and an active oxyhalide electrolyte; The volume ratio of the positive electrode material layer to the electrolyte layer in the composite positive electrode is ≤1:2; The positive electrode material layer is provided with a plurality of protrusions near the surface of the electrolyte layer; the electrolyte layer is provided with a plurality of recesses near the surface of the positive electrode material layer; the plurality of protrusions on the surface of the positive electrode material layer are matched with the plurality of recesses on the surface of the electrolyte layer; The depth of the concave hole on the surface of the electrolyte layer is 10% to 50% of the thickness of the electrolyte layer, and the area ratio of the plurality of concave holes on the surface of the electrolyte layer satisfies the following relationship: S1 / S2=40% to 60%; Wherein, S1 is the sum of the cross-sectional areas of the openings of the plurality of concave holes, and S2 is the area of the surface of the electrolyte layer on the side close to the positive material layer before the concave hole is set.

[0006] The inventors of the present application found through a large number of experimental researches that active halide and active halide oxide as solid-state electrolyte can have certain electrochemical activity, and can undergo reversible valence change during charging and discharging, providing additional capacity for the battery, and also providing ion channels as solid-state electrolyte. The selection of such electrolyte with high ionic conductivity and electronic insulation and the conventional positive electrode layer to form a composite positive electrode can provide more reversible capacity under the same positive electrode material load, and improve the specific capacity and energy density of the battery.

[0007] It should be noted that the inventors of the present application found in experiments that in order to make the selected solid-state electrolyte fully improve the electrochemical activity and specific capacity, the volume ratio between the positive material and the electrolyte layer needs to be controlled. If the proportion of the electrolyte layer is too low, it cannot provide enough additional capacity for the obtained all-solid-state battery, resulting in a decrease in the capacity of the all-solid-state battery.

[0008] In order to fully play the role of the electrolyte layer, the interface between the electrolyte layer and the positive material layer also needs to be controlled by interface engineering, so that the electrolyte layer and the positive material layer have mutually adaptive concave holes and protrusions (the concave holes and protrusions in the electrolyte layer and the positive material layer correspond to each other, and the size and depth need to be matched), so as to improve the contact area between the two. In the interface engineering of the present application, the depth of the concave hole on the surface of the electrolyte layer should not be less than 10% of the thickness of the electrolyte layer, otherwise it is difficult to form a close and buckled combination between the positive material layer and the electrolyte layer, which cannot reduce the interface resistance, and also cannot fully improve the contact area between the two. If the depth of the concave hole is too high, the positive material is difficult to deeply embed into the concave hole, resulting in gaps between the positive material layer and the electrolyte layer, which increases the internal resistance of the battery, reduces the ion transmission efficiency, and accelerates the performance decay of the battery. The typical but non-limiting depth of the concave hole is 10%, 15%, 18%, 20%, 25%, 30%, 40%, and 50% of the thickness of the electrolyte layer.

[0009] While ensuring full contact between the two layers by specifying the depth of the recessed holes, the area ratio of all recessed holes in the electrolyte layer is further limited. This area ratio represents the distribution of the positive electrode material within the electrolyte layer, thereby ensuring good contact between the two layers, fully maximizing the electrochemical activity of the electrolyte layer, and improving the utilization of the active electrolyte. A ratio of the sum of the recessed hole cross-sectional area to the area of ​​the electrolyte layer (before the recessed holes are installed) that is too high or too low will result in reduced utilization of the active electrolyte. Typical, but non-limiting, S1 / S2 ratios are 40%, 45%, 50%, 55%, and 60%.

[0010] In a specific embodiment of the present invention, the area ratio of all the concave holes on the surface of the electrolyte layer can be adjusted by changing the shape, pore size, pore spacing, etc. of the concave holes.

[0011] In a specific embodiment of the present invention, the thickness of the positive electrode material layer in the composite positive electrode is 5-150 μm, and the thickness of the electrolyte layer is 400-600 μm. More specifically, the thickness of the positive electrode material layer is the thickness excluding the protruding portion.

[0012] In a specific embodiment of the present invention, the composite positive electrode includes a positive electrode material layer and an electrolyte layer stacked in sequence. More specifically, the projected areas of the positive electrode material layer and the electrolyte layer on the plane in which they are stacked are equal (i.e., ignoring protrusions and recesses, the area of ​​the positive electrode material layer projected onto the stacking plane is equal to the area of ​​the electrolyte layer projected onto the stacking plane). Therefore, the volume ratio of the positive electrode material layer and the electrolyte layer can be replaced by the thickness ratio of the positive electrode material layer and the electrolyte layer.

[0013] Preferably, the volume ratio of the positive electrode material layer to the electrolyte layer in the composite positive electrode is (0.02-1):2.

[0014] More preferably, the volume ratio of the positive electrode material layer to the electrolyte layer in the composite positive electrode is (0.1-0.8):2.

[0015] Preferably, the active halide electrolyte comprises Li x V y Cl6、Li x Ti y Cl6、Li x Fe y Cl4、Li x Ta y Cl6、Li x Nb y Cl6、Li x Nb y Ta z At least one of Cl6; The Li x V y In Cl6, 0<x<4, 1≤y≤1.5; The Li x Ti y In Cl6, 0<x<4, 1≤y≤1.5; The Li x Fe y In Cl4, 0<x≤2, 1≤y<2; The Li x Ta y In Cl6, 0<x<4, 0<y<2; The Li x Nb y In Cl6, 0<x<4, 0<y<2; The Li x Nb y Ta z In Cl6, 0<x<4, 0<y<2, 0<z<2.

[0016] Typical but non-limiting Li x V y Cl6 includes Li3VCl6.

[0017] Typical but non-limiting Li x Ti y Cl6 includes Li3TiCl6.

[0018] Typical but non-limiting Li x Fe y Cl4 includes Li2FeCl4.

[0019] Typical but non-limiting Li x Ta y Cl6 includes LiTaCl6.

[0020] Typical but non-limiting Li x Nb y Cl6 includes LiNbCl6.

[0021] Typical but non-limiting Li x Nb y Ta z Cl6 including LiNb 0.5 Ta 0.5 Cl6.

[0022] Preferably, the active oxyhalide electrolyte comprises Li x Nb y OCl4、Li x Ta y OCl4、Li x Nb y Ta z At least one of OCl4; the Li x Nb y OCl4, wherein 0 < x < 4, 0 < y < 2; the Li x Ta y OCl4, wherein 0 < x < 4, 0 < y < 2; the Li x Nb y Ta z OCl4, wherein 0 < x < 4, 0 < y < 2, 0 < z < 2.

[0023] Typically but not limitedly, the Li x Nb y OCl4includes LiNbOCl4.

[0024] Typically but not limitedly, the Li x Ta y OCl4includes LiTaOCl4.

[0025] Typically but not limitedly, the Li x Nb y Ta z OCl4includes LiNb 0.5 Ta 0.5 OCl4.

[0026] The above halides and oxyhalides are electrolyte substances with electrochemical activity verified by the inventors of the present application through a large number of experiments. Other electrolytes commonly used in the art, such as Li3YCl6, Li 1.75 ZrO 0.5 Cl 4.75 and the like, are found by the inventors of the present application to have no electrochemical activity, and thus do not belong to active halide electrolytes or active oxyhalide electrolytes.

[0027] More preferably, the active electrolyte includes an active oxyhalide electrolyte.

[0028] Preferably, the opening of the concave hole is circular with a diameter of 0.02-0.06 mm.

[0029] If the opening aperture of the concave hole is too small, the positive material particles are difficult to fully penetrate into the electrolyte layer. If the aperture is too large, the positive material is prone to agglomeration.

[0030] In the specific embodiments of the present application, the diameters of the openings of all the concave holes on the surface of the electrolyte layer are equal or similar (error ≤1%).

[0031] Preferably, the hole spacing of the concave hole is 0.05-0.1 mm.

[0032] If the hole spacing is too large, it means that the hole diameter can be too small in the case of ensuring S1 / S2=40%-60%; vice versa. Therefore, the hole spacing of the concave hole is preferably 0.05-0.1 mm.

[0033] In the specific embodiments of the present application, the hole spacing of the concave hole refers to the spacing between the edges of two adjacent concave holes.

[0034] Preferably, the concave holes are regularly arranged on the surface of the electrolyte layer.

[0035] In the specific embodiments of the present application, the concave holes are distributed on the surface of the electrolyte layer in a square arrangement. That is, the line formed between the centers of the cross sections of any two adjacent concave holes is a side of a square.

[0036] In the specific embodiments of the present application, S1=nπ(1 / 2×d) 2 wherein n is the number of concave holes on the surface of the electrolyte layer, and d is the diameter of the cross section of the circular concave hole. The change of the hole diameter and the hole spacing will result in the change of the number n of the concave holes that can be arranged on the plane of the electrolyte layer.

[0037] Preferably, the depth of the concave hole on the surface of the electrolyte layer is 20%-30% of the thickness of the electrolyte layer.

[0038] Preferably, the positive electrode material layer comprises the following mass parts of the preparation raw materials: 60-100 parts of positive electrode active material, 0-30 parts of active electrolyte, 0-10 parts of conductive agent, and 0-5 parts of binder.

[0039] The preparation raw materials of the positive electrode material in the all-solid-state battery usually further comprise a solid-state electrolyte. In the present application, since the specific solid-state electrolyte selected has electrochemical activity, the addition of the active electrolyte to the preparation raw materials of the positive electrode material layer can play the role of the positive electrode active material, while having good high-voltage stability, high ionic conductivity and electronic insulation, thereby further effectively increasing the active material ratio in the all-solid-state battery.

[0040] More preferably, the total mass parts of all the preparation raw materials in the positive electrode material layer are 60-145 parts.

[0041] More preferably, the positive electrode active material comprises at least one of LiCoO2, LiFePO4, LiMn2O4, LiNi x Co y Mn z O2, xLi2MnO3·(1-x)LiNi a Co b Mn c O2, Li2S, Mo6S8, TiS2.

[0042] In the detailed description of the present application, the LiNi x Co y Mn z O2, x+y+z=1. A typical but non-limiting LiNi x Co y Mn z O2 material includes LiNi 1 / 3 Co 1 / 3 Mn 1 / 3 O2, LiNi 0.5 Co 0.2 Mn 0.3 O2.

[0043] In the detailed description of the present application, the xLi2MnO3·(1-x)LiNi a Co b Mn c O2, 0 a Co b Mn c O2 material includes 0.5Li2MnO3·0.5LiNi 1 / 3Co 1 / 3 Mn 1 / 3 O2, 0.5Li2MnO3·0.5LiNi 0.5 Co 0.2 Mn 0.3 O2.

[0044] More preferably, the conductive agent includes at least one of conductive carbon black, VGCF (vapor grown carbon fiber), acetylene black, ketjen black, carbon nanotube, graphene.

[0045] More preferably, the binder includes at least one of polytetrafluoroethylene, polyamide, polyester, vinyl acetate copolymer.

[0046] Preferably, the negative electrode includes a buffer layer and a negative electrode lithium-containing active material.

[0047] In the detailed description of the present application, the thickness of the negative electrode is 55 ~ 250 μm.

[0048] In the detailed description of the present application, the all-solid-state battery includes a composite positive electrode and a negative electrode stacked in sequence. More specifically, the composite positive electrode and the negative electrode have equal projected areas on the plane in which they are stacked.

[0049] More preferably, the preparation raw material of the buffer layer includes at least one of halide solid electrolyte, sulfide solid electrolyte, nitride solid electrolyte, hydride solid electrolyte, and anti-perovskite solid electrolyte.

[0050] More preferably, the halide solid electrolyte includes at least one of Li3YCl6, Li3YbCl6, Li3LuCl6, Li3YCl 4.5 Br 1.5 .

[0051] More preferably, the sulfide solid electrolyte includes at least one of Li6PS5Cl, Li 10 GeP2S 12 , Li7P3S 11 .

[0052] More preferably, the nitride solid electrolyte includes Li3N, and the Li3N includes at least one of α-Li3N and β-Li3N.

[0053] More preferably, the hydride solid electrolyte includes LiBH4 and / or a derivative thereof.

[0054] More preferably, the anti-perovskite solid electrolyte includes at least one of Li3OCl, Li2OHCl, Li2OHBr, and a derivative thereof.

[0055] More preferably, the negative electrode lithium-containing active material includes at least one of lithium metal, lithium-rich alloy, and lithium-carbon material.

[0056] More preferably, the lithium-rich alloy includes at least one of lithium-indium alloy Li x In, lithium-silicon alloy Li x Si, lithium-aluminum alloy, lithium-tin alloy, lithium-magnesium alloy, and lithium-zinc alloy.

[0057] More preferably, the lithium-carbon material includes LiC x , and the like lithium-carbon composite.

[0058] More preferably, the volume ratio of the buffer layer to the negative electrode lithium-containing active material in the negative electrode is (15-45):(2-5).

[0059] In the detailed description of the present application, the negative electrode includes a buffer layer and a negative electrode lithium-containing active material stacked in sequence. More specifically, the all-solid-state battery includes a positive electrode material layer, an electrolyte layer, a buffer layer, and a negative electrode lithium-containing active material stacked in sequence. More specifically, the positive electrode material layer, the electrolyte layer, the buffer layer, and the negative electrode lithium-containing active material have equal projected areas on the stacking plane.

[0060] In the detailed description of the present application, the thickness of the buffer layer is 50-150 μm.

[0061] In the detailed description of the present application, the thickness of the lithium-containing active material of the negative electrode is 5-100 μm.

[0062] Preferably, the all-solid-state battery further comprises a positive electrode current collector and a negative electrode current collector.

[0063] In the detailed description of the present application, the positive electrode current collector can be selected from conventional positive electrode current collectors in the art, including positive electrode metal current collectors and / or positive electrode composite current collectors. More specifically, the positive electrode metal current collector includes aluminum foil and / or nickel foil. More specifically, the positive electrode composite current collector includes at least one of metal-carbon material composite foil, polymer-electrically conductive material composite foil, plant fiber composite foil, and polymer-metal material composite foil.

[0064] In the detailed description of the present application, the negative electrode current collector can be selected from conventional negative electrode current collectors in the art, including negative electrode metal current collectors and / or negative electrode composite current collectors. More specifically, the negative electrode metal current collector includes copper foil and / or nickel foil. More specifically, the negative electrode composite current collector includes at least one of metal-carbon material composite foil, polymer-electrically conductive material composite foil, plant fiber composite foil, and polymer-metal material composite foil.

[0065] In the detailed description of the present application, the all-solid-state battery comprises a positive electrode current collector, a composite positive electrode, a negative electrode, and a negative electrode current collector stacked in sequence.

[0066] The present application also protects a preparation method of the above all-solid-state battery, comprising the following steps: S1. mixing raw materials for preparing the positive electrode material in proportion to obtain the positive electrode material; S2. forming the active electrolyte to obtain an electrolyte layer, etching the surface of the electrolyte layer to obtain an electrolyte layer with a plurality of pores on the surface, and then coating the positive electrode material obtained in step S1 on the surface to obtain a composite positive electrode; S3. assembling the composite positive electrode and the negative electrode to obtain the all-solid-state battery.

[0067] Preferably, the mixing in step S1 is performed in an inert atmosphere.

[0068] Preferably, the mixing in step S1 is performed by ball milling, and the rotation speed of the ball milling is 100-600 rpm.

[0069] Preferably, the forming in step S2 comprises cold pressing, and the pressure of the cold pressing is 200-500 MPa.

[0070] Preferably, the etching in step S2 comprises laser etching.

[0071] The pulse laser has no thermal influence zone, and the melting point of the oxyhalide is lower than that of other electrolyte materials, so it is easier to precisely process the laser ablation on the oxyhalide interface layer into a target structure without affecting the non-processed area, thereby helping the electrode layer and the solid-state electrolyte to be closely embedded with each other, significantly reducing the interface resistance and improving the utilization rate of the active material of the interface layer, so that the full solid-state battery based on the integrated positive electrode has the advantages of high specific capacity, high energy density, high safety, etc.

[0072] More preferably, the power of the laser etching in step S2 is 10 6 ~10 8 W / cm 2 , the frequency is 20-80 KHz, and the filling interval is 0.05-0.1 mm.

[0073] More preferably, after the coating in step S2, a cold pressing step is further included.

[0074] More preferably, the pressure of the cold pressing is 300-600 MPa.

[0075] More preferably, after the assembling in step S3, a packaging step is further included.

[0076] The packaging comprises coating the block obtained after assembling the composite positive electrode and the negative electrode with an aluminum alloy.

[0077] More preferably, after the packaging, a pressurizing step is further included, and the pressurizing comprises pressurizing the packaged block obtained after the packaging in a direction perpendicular to the interface between the positive electrode material layer and the electrolyte layer, and the pressure of the pressurizing is 50-100 MPa.

[0078] The purpose of the pressurizing is to promote the compounding between different material layers.

[0079] It should be noted that after the forming in step S2 in the present application, each layer has been pressed to be dense, so the subsequent cold pressing and pressurizing have a slight effect on the thickness of each layer, which does not need to be considered.

[0080] The present application also protects the application of the full solid-state battery in energy storage equipment, electric vehicles, and portable electronic devices.

[0081] Compared with the prior art, the present application has the following beneficial effects: The full solid-state battery provided by the present application has excellent specific capacity, and the discharge specific capacity can reach 312 mAh / g or more according to the mass of the positive electrode active material, and the discharge specific capacity can reach 202 mAh / g or more according to the total mass of the positive electrode. BRIEF DESCRIPTION OF DRAWINGS

[0082] Figure 1 A schematic diagram of a structure of a full solid-state battery according to the present application, wherein 1 is a positive current collector, 2 is a composite positive electrode, 21 is a positive electrode material layer, 22 is an electrolyte layer, 3 is a negative electrode buffer layer, 4 is a negative electrode lithium-containing active material, and 5 is a negative current collector.

[0083] Figure 2 An enlarged view of an interface between the positive electrode material layer and the electrolyte layer of the full solid-state battery according to the present application, wherein 6 is the depth of the concave hole, 61 is the cross-sectional diameter of the concave hole, and 62 is the spacing between the concave holes.

[0084] Figure 3 A charge-discharge curve diagram of the first three cycles of the full solid-state battery according to Example 1 of the present application.

[0085] Figure 4 A charge-discharge curve diagram of the first three cycles of the full solid-state battery according to Comparative Example 9 of the present application. DETAILED DESCRIPTION

[0086] The present application will be further described below in conjunction with specific embodiments, but the embodiments do not limit the present application in any form. Unless otherwise specified, the raw materials used in the embodiments of the present application are commercially available raw materials.

[0087] Examples 1-8 and Comparative Examples 1-8 The present examples and comparative examples provide a series of full solid-state batteries with different volume ratios of positive electrode material layers to electrolyte layers and different surface pore structures of electrolyte layers, the full solid-state batteries including composite positive electrodes and negative electrodes, The composite positive electrode includes a positive electrode material layer with a thickness of 6-200 μm and an electrolyte layer with a thickness of about 300-544 μm (the projected areas of both on the stacking plane are 0.785 cm 2 ), the preparation raw materials of the positive electrode material layer include the following substances in mass parts: 65 parts of LiCoO2, 30 parts of LiNbOCl4, 3 parts of VGCF, and 2 parts of PTFE, The preparation raw materials of the electrolyte layer include active electrolyte LiNbOCl4. The volume ratio (i.e. thickness ratio) of the positive electrode material layer to the electrolyte layer in the composite positive electrode is (0-67): 100, wherein the positive electrode material layer is provided with a plurality of protrusions on the surface close to the electrolyte layer, the electrolyte layer is provided with a plurality of recesses on the surface close to the positive electrode material layer, the plurality of protrusions on the surface of the positive electrode material layer are matched with the plurality of recesses on the surface of the electrolyte layer; the opening of the recess is circular (the recess is cylindrical), the diameter is 0-0.1 mm, the depth is 0-400 μm (0%-80% of the thickness of the electrolyte layer), and the hole spacing of the recess is 0-0.2 mm; the recess satisfies S1 / S2=0%-96%, wherein S1 is the sum of the cross-sectional areas of the openings of the plurality of recesses, and S2 is the area of the surface of the electrolyte layer close to the positive electrode material layer before the recess is set; The negative electrode comprises a buffer layer and a negative electrode lithium-containing active material with a thickness of 50 μm stacked in sequence, the buffer layer is prepared from Li3YCl6 electrolyte, and the negative electrode lithium-containing active material is lithium-indium alloy Li x In; The structure of the all-solid-state battery is that the positive electrode material layer, the electrolyte layer, the negative electrode buffer layer, and the negative electrode lithium-containing active material are stacked in sequence.

[0088] The preparation method of the all-solid-state battery in the embodiment and the comparative example comprises the following steps: S1. In an argon atmosphere, the preparation raw materials of the positive electrode material layer are mixed in proportion, and the positive electrode material is obtained by ball milling under 400 rpm; S2. LiNbOCl4 powder is cold-pressed under 300 MPa to obtain an electrolyte layer, and a fiber pulse laser is used to etch the surface of the electrolyte layer, the power of the laser etching is 3×10 6 W / cm 2 , the frequency is 40 KHz, and the filling interval is 0.05 mm; after etching, the electrolyte layer with a plurality of channels on the surface is obtained, then the positive electrode material obtained in step S1 is coated on the surface to form a positive electrode material layer, and the composite positive electrode is obtained by cold-pressing again under 500 MPa; S3. The surface of the electrolyte layer in the composite positive electrode is covered with Li3YCl6 electrolyte as a negative electrode buffer layer, and then the lithium-indium alloy is covered on the surface of the negative electrode buffer layer, and the all-solid-state battery is assembled by applying a pressure of 50 MPa.

[0089] The variables involved in the all-solid-state batteries provided in the embodiment and the comparative example are shown in Table 1: Table 1. Differences of the all-solid-state batteries in the embodiment and the comparative example Note: The "pore area ratio" in Table 1 above means S1 / S2, where S1 is the sum of cross-sectional areas of all pores, and S2 is the projected area of the surface of the electrolyte layer on the side close to the positive electrode material layer.

[0090] The structure of the all-solid-state battery provided in Example 1 is shown in Figures 1-2 Figure 1 In the figure, 1 indicates a positive electrode current collector, 2 is a composite positive electrode, where 21 is a positive electrode material layer, and 22 is an electrolyte layer, 3 is a negative electrode buffer layer, 4 is a negative electrode lithium-containing active material, and 5 is a negative electrode current collector. Figure 2 The enlarged view of the interface between the positive electrode material layer and the electrolyte layer of the all-solid-state battery provided in the present application is shown in the figure, where 6 is the depth of the pores, 61 is the cross-sectional diameter of the pores, and 62 is the distance between the pores.

[0091] Example 9 An all-solid-state battery, wherein the only difference from Example 1 is that: The raw materials for preparing the positive electrode material layer include 65 parts of LiCoO2, 23 parts of LiNbOCl4, 10 parts of VGCF, and 2 parts of PTFE.

[0092] The preparation method of the all-solid-state battery in this example is carried out according to Example 1.

[0093] Example 10 An all-solid-state battery, wherein the only difference from Example 1 is that: The raw materials for preparing the positive electrode material layer include 80 parts of LiCoO2, 15 parts of LiNbOCl4, 3 parts of VGCF, and 2 parts of PTFE.

[0094] The preparation method of the all-solid-state battery in this example is carried out according to Example 1.

[0095] Example 11 An all-solid-state battery, wherein the only difference from Example 1 is that: The raw materials for preparing the positive electrode material layer include 90 parts of LiCoO2, 5 parts of LiNbOCl4, 3 parts of VGCF, and 2 parts of PTFE.

[0096] The preparation method of the all-solid-state battery in this example is carried out according to Example 1.

[0097] Example 12 An all-solid-state battery, wherein the only difference from Example 1 is that: The raw materials for preparing the electrolyte layer include the active electrolyte LiTaOCl4.

[0098] The preparation method of the all-solid-state battery in this example is carried out according to Example 1. ​

[0099] Example 13 A full solid-state battery, wherein the only difference from Example 1 is that: The preparation raw material of the electrolyte layer comprises an active electrolyte LiNbCl6.

[0100] The preparation method of the full solid-state battery in this example is carried out according to Example 1.

[0101] Example 14 A full solid-state battery, wherein the only difference from Example 1 is that: The preparation raw material of the electrolyte layer comprises an active electrolyte LiTaCl6.

[0102] The preparation method of the full solid-state battery in this example is carried out according to Example 1.

[0103] Comparative Example 9 A full solid-state battery, wherein the only difference from Example 1 is that: The preparation raw material of the electrolyte layer comprises Li3YCl6.

[0104] The preparation method of the full solid-state battery in this example is carried out according to Example 1.

[0105] Comparative Example 10 A full solid-state battery, wherein the only difference from Example 1 is that: The preparation raw material of the electrolyte layer comprises Li 1.75 ZrO 0.5 Cl 4.75 .

[0106] The preparation method of the full solid-state battery in this example is carried out according to Example 1.

[0107] Performance test Discharge specific capacity test: the full solid-state batteries obtained in the examples and comparative examples are connected to the battery charge-discharge equipment Blue Electric CT3002A to test the discharge specific capacity, and the data in the 3rd cycle after starting the test is taken as the reference.

[0108] The specific performance test data are shown in Table 2 and Table 3 as follows: Figures 3-4 Table 2. Performance test data of the full solid-state batteries obtained in the examples and comparative examples According to the data in Table 2 above, the full solid-state battery provided by the application has excellent specific capacity, and the discharge specific capacity can reach 312 mAh / g or more according to the mass of the positive electrode active material, and the discharge specific capacity can reach 202 mAh / g or more according to the total mass of the positive electrode.

[0109] ​According to the data of Examples 1-3 and Comparative Example 4 in Table 2, it can be seen that the volume ratio of the positive electrode material layer to the electrolyte layer in the composite positive electrode of the present application should satisfy ≤1:2, so as to ensure that the electrolyte layer can provide sufficient additional capacity for the obtained full solid-state battery, and improve the specific capacity of the full solid-state battery. Comparative Example 4 is a commonly used scheme to improve the capacity of the full solid-state battery at present (i.e., try to increase the thickness and volume of the positive electrode as much as possible, and make the electrolyte as thin and small as possible, so as to fully play the role of the positive electrode), and according to the data of Comparative Example 4, it can be seen that this cannot fully play the role of the electrolyte layer to provide additional capacity, so the capacity of the obtained full solid-state battery is insufficient. At the same time, according to the data of Examples 1-3, it can be seen that the proportion of the electrolyte layer should not be too high, and the volume ratio of the positive electrode material layer to the electrolyte layer should be in the range of (0.1-0.8):2 (Examples 1-2) in the present application, and the capacity of the obtained battery is higher.

[0110] According to the data of Examples 1, 4-5, 8 and Comparative Examples 1-3, it can be seen that the recesses on the surface of the electrolyte layer need to satisfy a depth of 10%-50% of the thickness of the electrolyte layer, so as to ensure sufficient contact between the electrolyte layer and the positive electrode material layer. If the depth of the recesses on the surface of the electrolyte layer is less than 10% of the thickness of the electrolyte layer (Comparative Example 3), it is difficult to form a close and buckled combination between the positive electrode material layer and the electrolyte layer, which cannot reduce the interface resistance, and also cannot sufficiently increase the contact area between the two; if the depth of the recesses is too high (Comparative Example 2), the positive electrode material is difficult to deeply embed into the recesses, resulting in gaps between the positive electrode material layer and the electrolyte layer, which in turn increases the internal resistance of the battery, reduces the ion transmission efficiency, and accelerates the performance decay of the battery. According to the data of Comparative Examples 1, 4-5 and 8, it can be seen that when the depth of the recesses on the surface of the electrolyte layer is 20%-30% of the thickness of the electrolyte layer (Example 1), it can better promote the contact between the electrolyte layer and the positive electrode material layer, and sufficiently increase the capacity.

[0111] According to Examples 6-7 and Comparative Examples 5-8, it can be seen that by adjusting the aperture and pitch of the recesses on the surface of the electrolyte layer, the area ratio of the recesses can be adjusted, and when the area ratio of the recesses does not satisfy the condition of S1 / S2=30%-70% in the present application, it cannot sufficiently promote the contact between the electrolyte layer and the positive electrode material layer, resulting in separate aggregation of the electrolyte and the positive electrode material, and reducing the utilization rate of active substances.

[0112] According to Examples 12-14 and Comparative Examples 9-10, it can be seen that using non-active electrolyte material to construct the electrolyte layer cannot utilize the active electrolyte to provide additional capacity for the positive electrode, and thus cannot improve the specific capacity of the full solid-state battery.

[0113] Finally, it should be noted that the above examples are merely intended to illustrate the technical solutions of the present application and not to limit the protection scope of the present application. Although the present application has been described in detail with reference to the preferred embodiments, those skilled in the art should understand that the technical solutions of the present application can be modified or equivalently replaced without departing from the essence and scope of the technical solutions of the present application.

Claims

1. An all-solid-state battery, characterized in that: Including composite positive and negative electrodes, The composite positive electrode comprises a positive electrode material layer and an electrolyte layer, wherein the raw materials for preparing the electrolyte layer include an active electrolyte, and the active electrolyte includes at least one of an active halide electrolyte and an active halide oxide electrolyte; The volume ratio of the positive electrode material layer to the electrolyte layer in the composite positive electrode is ≤1:2; The surface of the positive electrode material layer close to the electrolyte layer is provided with a plurality of protrusions; the surface of the electrolyte layer close to the positive electrode material layer is provided with a plurality of recessed holes; the plurality of protrusions on the surface of the positive electrode material layer are adapted to the plurality of recessed holes on the surface of the electrolyte layer; The depth of the concave holes on the surface of the electrolyte layer is 10% to 50% of the thickness of the electrolyte layer, and the area ratio of the plurality of concave holes on the surface of the electrolyte layer satisfies the following relationship: S1 / S2=40%~60%; Wherein, S1 is the sum of the cross-sectional areas of the openings of the plurality of recessed holes, and S2 is the area of ​​the surface of the electrolyte layer close to the positive electrode material layer before the recessed holes are provided.

2. The all-solid-state battery according to claim 1, wherein: The active halide electrolyte includes Li x V y Cl6、Li x Ti y Cl6、Li x Fe y Cl4、Li x Ta y Cl6、Li x Nb y Cl6、Li x Nb y Ta z At least one of Cl6; And / or, the active oxyhalide electrolyte includes Li x Nb y OCl4、Li x Ta y OCl4、Li x Nb y Ta z At least one of OCl4; The Li x V y In Cl6, 0<x<4, 1≤y≤1.5; The Li x Ti y In Cl6, 0<x<4, 1≤y≤1.5; The Li x Fe y In Cl4, 0<x≤2, 1≤y<2; The Li x Ta y In Cl6, 0<x<4, 0<y<2; The Li x Nb y In Cl6, 0<x<4, 0<y<2; The Li x Nb y Ta z In Cl6, 0<x<4, 0<y<2, 0<z<2; The Li x Nb y In OCl4, 0<x<4, 0<y<2; The Li x Ta y In OCl4, 0<x<4, 0<y<2; The Li x Nb y Ta z In OCl4, 0<x<4, 0<y<2, 0<z<2.

3. The all-solid-state battery according to claim 1, wherein: The opening of the concave hole is circular with a diameter of 0.02-0.06 mm; And / or, the hole spacing of the concave holes is 0.05-0.1 mm; And / or, the depth of the concave pores on the surface of the electrolyte layer is 20% to 30% of the thickness of the electrolyte layer.

4. The all-solid-state battery according to claim 1, wherein: The positive electrode material layer includes the following raw materials in parts by weight: 60~100 parts of positive electrode active material, 0~30 parts of active electrolyte, 0~10 parts of conductive agent, and 0~5 parts of binder.

5. The all-solid-state battery according to claim 4, wherein: The positive electrode active material includes LiCoO2, LiFePO4, LiMn2O4, LiNi x Co y Mn z O2、xLi2MnO3·(1-x)LiNi a Co b Mn c At least one of O2, Li2S, Mo6S8, TiS2.

6. The all-solid-state battery according to claim 1, wherein: The volume ratio of the composite positive electrode to the negative electrode is (50-80): (17-50); And / or, the negative electrode includes a buffer layer and a negative electrode lithium-containing active material.

7. The all-solid-state battery according to claim 6, wherein: The raw materials for preparing the buffer layer include at least one of a halide solid electrolyte, a sulfide solid electrolyte, a nitride solid electrolyte, a hydride solid electrolyte, and an antiperovskite solid electrolyte; And / or, the negative electrode lithium-containing active material includes at least one of lithium metal, lithium-rich alloy, and lithium-carbon material; And / or, the volume ratio of the buffer layer in the negative electrode to the negative electrode lithium-containing active material is (15-45): (2-5).

8. A method for preparing the all-solid-state battery according to any one of claims 1 to 7, characterized in that: The steps include: S1. The raw materials for preparing the positive electrode material layer are mixed in proportion to obtain a positive electrode material; S2. The active electrolyte is formed into an electrolyte layer, and the surface of the electrolyte layer is etched to obtain an electrolyte layer having a plurality of concave pores on the surface. The cathode material obtained in step S1 is then coated on the surface to obtain a composite cathode. S3. Assemble the composite positive electrode and negative electrode to obtain an all-solid-state battery.

9. The method for preparing an all-solid-state battery according to claim 8, wherein: The etching in step S2 includes laser etching.

10. Use of the all-solid-state battery according to any one of claims 1 to 7 in energy storage devices, electric vehicles, and portable electronic devices.

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