Battery

Abstract

The present application discloses a battery. The battery is assembled by stacking a positive electrode sheet, a buffer layer, a solid electrolyte layer, and a negative electrode sheet in sequence; wherein the positive electrode sheet includes a first active material and a first solid electrolyte; the buffer layer includes a second active material and a second solid electrolyte; the first mass proportion of the first solid electrolyte in the total amount of the first active material and the first solid electrolyte does not exceed 40%, and the second mass proportion of the second solid electrolyte in the total amount of the second active material and the second solid electrolyte is 50%-80%, and the ratio of the second mass proportion to the first mass proportion is greater than 1.6. The present application avoids the micro-short circuit problem that occurs in existing batteries by placing a buffer layer in the positive electrode sheet and the solid electrolyte layer, thereby achieving excellent electrical performance while ensuring high energy density of the battery.

Description

Technical Field

[0001] The present application relates to the field of chemical energy technology, and in particular to an ultra-low liquid content solid-state or solid-state battery using a buffer layer. Background Art

[0002] With the rapid development of new energy technology, ultra-low liquid content solid-state batteries (liquid content <5%) or solid-state batteries have become one of the main directions of future energy development. Currently, ultra-low liquid content solid-state batteries or solid-state batteries are composed of a positive electrode sheet, a solid electrolyte layer (the thickness of the layer is generally ), the negative electrode sheets are stacked in sequence and then pressed. During the pressing process (pressure is usually >300MPa), due to the poor mechanical properties of the solid electrolyte membrane and the high hardness and inability to guarantee absolute uniformity and flatness of the positive electrode sheets, the solid electrolyte layer can easily be pressed through or unevenly pressed during the battery pressing process, causing micro-short circuits during the battery cycle and affecting battery performance. Summary of the Invention

[0003] To address the aforementioned issues, this application discloses a battery. The battery may include an ultra-low liquid content solid-state battery or an all-solid-state battery. The battery includes a buffer layer positioned between the positive electrode and the solid-state electrolyte layer. This layer addresses micro-short circuit issues while maintaining high energy density, achieving excellent electrical performance.

[0004] The present application discloses a battery, which is assembled by stacking a positive electrode sheet, a buffer layer, a solid electrolyte layer, and a negative electrode sheet in sequence; wherein the positive electrode sheet includes a first active material and a first solid electrolyte; the buffer layer includes a second active material and a second solid electrolyte; the first mass proportion of the first solid electrolyte in the total amount of the first active material and the first solid electrolyte does not exceed 40%, the second mass proportion of the second solid electrolyte in the total amount of the second active material and the second solid electrolyte is 50%-80%, and the ratio of the second mass proportion to the first mass proportion is greater than 1.6.

[0005] According to some embodiments of the present application, the solid electrolyte layer includes a third solid electrolyte; the first volume average particle size of the first solid electrolyte does not exceed the second volume average particle size of the second solid electrolyte; and the second volume average particle size does not exceed the third volume average particle size of the third solid electrolyte.

[0006] According to some embodiments of the present application, a ratio of the third volume average particle size to the first volume average particle size is greater than 1.2.

[0007] According to some embodiments of the present application, the first active material and the second active material are the same as or different; the first solid electrolyte, the second solid electrolyte, and the third solid electrolyte are the same as or different.

[0008] According to some embodiments of the present application, the fourth volume average particle size of the first active material is not smaller than the fifth volume average particle size of the second active material.

[0009] According to some embodiments of the present application, the thickness of the buffer layer is .

[0010] According to some embodiments of the present application, the thickness of the buffer layer is not less than 5% of the thickness of the positive electrode sheet and not more than 60% of the thickness of the solid electrolyte layer.

[0011] The liquid content in the battery is less than 5%;

[0012] Further preferably, the liquid content is less than <1%;

[0013] Further preferably, the liquid content is less than <0.01%;

[0014] According to some embodiments of the present application, a ratio of a fourth volume average particle size of the first active material to a first volume average particle size of the first solid electrolyte is greater than 2.

[0015] According to some embodiments of the present application, a ratio of a fifth volume average particle size of the second active material to a second volume average particle size of the second solid electrolyte is greater than 1.2.

[0016] According to some embodiments of the present application, the positive electrode plate also includes a first conductive agent and a first binder, the buffer layer also includes a second conductive agent and a second binder, and the solid electrolyte layer includes a third binder; wherein the first conductive agent is the same as or different from the second conductive agent, and the first binder, the second binder, and the third binder are the same as or different.

[0017] Additional aspects and advantages of the present invention will be set forth in part in the description which follows and, in part, will be obvious from the description which follows, or may be learned through practice of the present invention. DETAILED DESCRIPTION

[0018] To make the above-mentioned objects, features, and advantages of the present application more clearly understood, the specific embodiments of the present application are described in detail below. The following description sets forth many specific details to facilitate a full understanding of the present application. However, the present application can be implemented in many other ways than those described herein, and those skilled in the art can make similar modifications without violating the scope of the present application. Therefore, the present application is not limited to the specific embodiments disclosed below.

[0019] Unless otherwise defined, all technical and scientific terms used in this application have the same meaning as commonly understood by those skilled in the art to which this application belongs. The terms used in this application and in the specification of this application are for the purpose of describing specific embodiments only and are not intended to limit this application. Words such as "include" or "comprise" used in this application mean that the elements or objects appearing before the word include the elements or objects listed after the word and their equivalents, without excluding other elements or objects. The terms "and / or" or "and / or" used in this application include any and all combinations of one or more related listed items.

[0020] At present, in order to solve the problems in battery compression molding, the solid electrolyte layer is thickened, such as The above problems can be alleviated by reducing the positive electrode active material loading and particle size in the positive electrode sheet, but this will result in a significant loss in the battery's energy density and electrical performance.

[0021] The battery disclosed in this application can solve related problems while ensuring the excellent electrical performance of the battery by adding a buffer layer to the positive electrode plate and the solid electrolyte layer.

[0022] Some preferred embodiments of the present application are described below. It should be noted that the following description is for illustrative purposes and is not intended to limit the scope of protection of the present application. The steps involved in the present application can be performed precisely in order, or various steps can be processed in reverse order or simultaneously. At the same time, other operations can be added to these processes, or one or more operations can be removed from these processes.

[0023] This application discloses a battery, which may include an ultra-low liquid content solid-state battery or an all-solid-state battery. The battery can be assembled by sequentially stacking a positive electrode sheet, a buffer layer, a solid electrolyte layer, and a negative electrode sheet. The buffer layer is disposed between the positive electrode sheet and the solid electrolyte layer, providing pressure relief and electrical conductivity compensation for the solid electrolyte layer.

[0024] It can be understood that a low-liquid solid-state battery refers to a battery with a liquid content of less than 5%, and an all-solid-state battery refers to a battery that contains basically no liquid.

[0025] The positive electrode sheet may include a first active material and a first solid electrolyte. As an example, the first active material may include but is not limited to a layered oxide material (e.g., lithium cobalt oxide LiCoO2, nickel cobalt manganese ternary material LiNi x Co y Mn 1-x- y O2, nickel-cobalt-aluminum ternary material LiNi x Co y Al 1-x-y O2, etc.), spinel structure materials (for example, lithium manganate LiMn2O4, high voltage nickel manganese spinel LiNi 0.5 Mn 1.5 O4, etc.), olivine structure materials (e.g., lithium iron phosphate LiFePO4, etc.), sulfur-based materials (e.g., elemental sulfur S, transition metal chalcogenides, and composites thereof), conversion-type positive electrode materials (e.g., metal fluorides such as CoF2, FeF3, metal chlorides such as CoCl2, etc.), lithium-rich layered oxides (e.g., Li2MnO3·LiMO2, M=Ni, Co, Mn), polyanionic compounds (e.g., phosphates, pyrophosphates, sulfates, silicates, borates, and mixed polyanions), or any combination thereof. In some embodiments, the first positive electrode material may be a lithium salt, for example, an active material including lithium cobalt oxide, lithium iron phosphate, lithium manganese oxide, lithium nickel oxide, lithium nickel manganese oxide, lithium nickel cobalt manganese oxide, lithium nickel cobalt aluminum oxide, lithium-rich manganese-based materials, etc.

[0026] The first solid electrolyte may include, but is not limited to, a polymer solid electrolyte, an inorganic solid electrolyte, a glassy and glass-ceramic electrolyte, a composite solid electrolyte, or any combination thereof. Exemplary polymer solid electrolytes may include polyethylene oxide (PEO), poly(propylene oxide) (PPO), polyolefin polymer electrolytes (e.g., polyvinylidene fluoride (PVDF), poly(vinylidene fluoride-hexafluoropropylene) (PVDF-HFP), etc.), polyacrylonitrile (PAN)-based electrolytes, polymethyl methacrylate (PMMA)-based electrolytes, polyvinylpyrrolidone (PVP)-based electrolytes, polysiloxane-based electrolytes (e.g., polydimethylsiloxane (PDMS), etc.), ionic liquid polymer electrolytes (e.g., poly(ionic liquid), etc.), etc., or any combination thereof. The above polymer solid electrolytes can be used in combination with different types of lithium salts (e.g., LiClO4, LiTFSI, LiBF4, etc.) to achieve good flexibility and high ionic conductivity.

[0027] Exemplary inorganic solid electrolytes may include oxide solid electrolytes, halide solid electrolytes, sulfide solid electrolytes, etc. Among them, oxide solid electrolytes may include but are not limited to garnet-type solid electrolytes such as LLZO, LLTO, LBLTO, etc. or element substitution, NASICON-type solid electrolytes such as LTPA, LAGP, etc. or their element substitution, Li3xLa (2 / 3)-x TiO3、Li 0.34 La 0.51 TiO 2.94 Perovskite solid electrolytes such as Li3OCl, Li3OBr or their element substitution bodies, antiperovskite oxide electrolytes such as Li 14 ZnGe4O 16 , Li4SiO4, LiGeO4 or their element substitution bodies, LISICON type solid electrolytes such as Li3BO3, Li2B4O7 or their element substitution bodies, borate oxide electrolytes such as LLZO-LLTO, LATP-LLZO or other composite oxide electrolytes, or Li3PO4 or its N substitution bodies, etc. One or more of the above. Optionally or preferably, the inorganic oxide may include one or more of LLZO, LLTO, LAGP, LATP, LBSPO, LPO, Li4SiO4, Li2ZnTi3O8, and / or one or more of their derivatives. The halide solid electrolyte may be of the chemical formula Li a MX b Indicates that M represents a metal element or a metalloid element, and X represents a halogen element. Wherein, "metalloid element" can represent an element with similar metal properties, and can include B, Si, Ge, As, Sb, Te, etc. Optionally or preferably, M can include but is not limited to Al, Zn, Mg, Ca, Ba, Mn, Zr, Cd, Co, Yb, Y, Cr, In, Ga, Sr, Hf, Ti, Ta, Sn, Nb, Er, Sc, etc. or any combination thereof. In some embodiments, M can be one or more of Y, In or Zr. For example, the halide solid electrolyte can be a Zr-based halide solid electrolyte, including Li2ZrCl6, Li3Zr2I9, Li2ZrI6, etc. For another example, the halide solid electrolyte can be an In-based halide solid electrolyte, including Li3InCl6, Li3InBr6, Li3InI6, Li3In2Cl9, etc. For example, the halide solid electrolyte can be a Y-based halide solid electrolyte, including Li3YCl6, Li3YBr6, Li3YI6, Li3Y(Cl 1-x Br x)6, etc. M and X in the above halide solid electrolytes can each contain two or more elements to form a mixed halide electrolyte. For example, Li2ZrCl 6-x Br x , Sulfide solid electrolytes can include but are not limited to lithium sulfide series (Li2S-P2S5 system, such as LGPS, Li7P3S 11 , Li3PS4, etc.), germanium sulfide series (such as LGPS, LSPS, etc.), tin sulfide series (such as Li4SnS4, etc.), lithium boron sulfide series (such as Li3BS3, etc.), sulfur halide series (such as Li6PS5X, Li3InX6, etc., X = Cl, Br, I), etc. or any combination thereof. Optionally or preferably, the sulfide solid electrolyte may include one or more of Li6PS5Cl, Li2S-P2S5, LGPS, etc.

[0028] Exemplary glassy and glass-ceramic electrolytes may include, but are not limited to, Li2O-B2O3-SiO2 systems, Li2S-P2S5 systems, LiF-AlF3 systems, Li2O-Al2O3-TiO2-P2O5 systems, Li2O-SiO2-P2O5 systems, 70Li2S·30P2S5 glass-ceramics, Li2S-P2S5-LiI systems, Li2S-P2S5-P2S3 systems, Li2O-B2O3-P2O5 systems, Li2O-Al2O3-GeO2-P2O5 systems, Li 1+x Al x Ti 2-x (PO4)3、Li 10 GeP2S 12 , Li3PS4-LiI composite electrolyte, Li2S-P2S5-LiBH4 system, etc., or any combination of multiple electrolytes.

[0029] Exemplary composite solid electrolytes may include inorganic-polymer composite electrolytes, inorganic-inorganic composite electrolytes, polymer-polymer composite electrolytes, ternary composite electrolytes and functionalized composite electrolytes, etc. Among them, inorganic-polymer composite electrolytes may include ceramic-filled polymer electrolytes such as PEO-LLZO, PEO-LAGP, etc., polymer-reinforced ceramic electrolytes such as LLZO-PEO, LATP-PEO, etc., polymer-coated ceramic electrolytes such as LGPS-PEO, etc. Inorganic-inorganic composite electrolytes may include oxide-oxide composite electrolytes such as LLZO-LATP, etc., sulfide-oxide composite electrolytes such as Li 10 GeP2S 12-Li3BO3, etc., halide-oxide composite electrolytes such as LiF-Li3YCl6, etc. Polymer-polymer composite electrolytes can include PEO-PVDF composite electrolytes, PEO-PAN composite electrolytes, PEO-PMMA composite electrolytes, etc. Ternary composite electrolytes can include polymer, ceramic, lithium salt ternary polymers such as PEO-LLZO-LiTFSI, polymer, inorganic filler, lithium salt ternary polymers such as PAN-SiO2-LiClO4, copolymer, ceramic, lithium salt ternary polymers such as PVDF-HFP-Al2O3-LiTFSI, etc. Functionalized composite electrolytes can include surface-modified LLZO-PEO composite electrolytes, cross-linked PEO-ceramic composite electrolytes, ionic liquid-enhanced composite electrolytes, etc.

[0030] The above-mentioned first solid electrolyte can also be modified, doped, or composited to enhance its physical and chemical properties, including improving stability, mechanical strength, and ionic conductivity. For example, a conductive polymer or protective layer may be coated on the surface of the first solid electrolyte, other metal elements such as Al, Mg, and Ca may be doped, two or more first solid electrolytes may be reused, or composited with carbon nanotubes (CNTs) or graphene.

[0031] In some embodiments, the mass fraction of the first solid-state electrolyte in the total mass of the first active material and the first solid-state electrolyte (referred to herein as the first mass fraction, denoted as w1) does not exceed 40%. Optionally or preferably, the first mass fraction does not exceed 34%. Optionally or preferably, the first mass fraction does not exceed 28%. Optionally or preferably, the first mass fraction does not exceed 22%. Optionally or preferably, the first mass fraction does not exceed 18%. Optionally or preferably, the first mass fraction does not exceed 10%. Alternatively, the first mass fraction can be any value within the above numerical ranges, such as 18%, 28%, etc.

[0032] The buffer layer may include a second active material and a second solid electrolyte. In some embodiments, the second active material may also be selected from one or more of the first active materials described above. That is, the second active material may be the same as or different from the first active material. For example, the second active material may be consistent with the first active material, both being layered oxide materials such as the nickel-cobalt-manganese ternary material LiNi x Co y Mn 1-x-yO2. Alternatively, the second active material can be lithium cobalt oxide, while the first active material is still the nickel-cobalt-manganese ternary material described above. The second solid electrolyte can also be one or more of the same or similar first solid electrolytes as described above. The two can also be the same or different. For example, the first solid electrolyte and the second solid electrolyte can both be Li2ZrCl6. Alternatively, the first solid electrolyte can be Li2ZrCl6, while the second solid electrolyte can be LLTO. This application does not limit the selection of the above components.

[0033] In some embodiments, the mass fraction of the second solid electrolyte in the total mass of the second active material and the second solid electrolyte (referred to herein as the second mass fraction, denoted as w2) is 50%-80%. Alternatively or preferably, the second mass fraction is 55%-75%. Alternatively or preferably, the second mass fraction is 60%-70%. Alternatively or preferably, the second mass fraction is 62%-68%. Alternatively or preferably, the second mass fraction is 64%-66%. Alternatively, the second mass fraction can be any value within the above numerical ranges, such as 50%, 60%, 70%, 80%, etc.

[0034] In some embodiments, the ratio of the second mass fraction to the first mass fraction, w2 / w1, may be greater than 1.6. For example, the ratio w2 / w1 may be 1.7, 1.8, 1.9, 2.0, 2.2, 2.4, 2.6, 2.8, 3.0, 3.5, 4.0, 5.0, or more. The ratio w2 / w1 may also be any value within the above numerical range, such as 1.79, 2.14, 2.17, 2.86, 3.33, or the like.

[0035] The solid electrolyte layer may include a third solid electrolyte. The same or similar third solid electrolyte may be one or more of the first solid electrolyte or the second solid electrolyte described above. That is, the first solid electrolyte, the second solid electrolyte and the third solid electrolyte may be the same or different. For example, completely different, two-to-two identical, or completely consistent. For example, all three may be Li2ZrCl6. Alternatively, the first solid electrolyte and the second solid electrolyte are both Li2ZrCl6, and the third solid electrolyte is Li6PS5Cl. Alternatively, the first solid electrolyte is Li2ZrCl6, the second solid electrolyte is LLTO, and the third solid electrolyte is Li6PS5Cl. This application does not specifically limit the selection of the above three solid electrolytes.

[0036] The aforementioned active materials (including the first active material and the second active material) and solid electrolytes (including the first solid electrolyte, the second solid electrolyte, and the third solid electrolyte) may be in particulate form and constitute their respective components (e.g., the positive electrode plate, the buffer layer, and the solid electrolyte layer). Measured by volume average particle size Dv50, the first volume average particle size (DE1) of the first solid electrolyte may not exceed the second volume average particle size (DE2) of the second solid electrolyte, and the third volume average particle size (DE3) of the third solid electrolyte may not be less than the second volume average particle size of the second solid electrolyte. Furthermore, the fourth volume average particle size (DC1) of the first active material may not be less than the fifth volume average particle size (DC2) of the second active material. The relationship between these parameters can be expressed as: DE1 ≤ DE2 ≤ DE3, DC1 ≥ DC2.

[0037] Among the aforementioned parameters, the ratio DC1 / DE1 between the fourth volume average particle size DC1 of the first active material of the positive electrode sheet and the first volume average particle size DE1 of the first solid electrolyte can be greater than 2. For example, the ratio DC1 / DE1 can be 2.3, 2.6, 2.9, 3.3, 3.6, or even greater. The ratio DC1 / DE1 can also be any value within the aforementioned numerical range, such as 3.33. The ratio DC2 / DE2 between the fifth volume average particle size DC2 of the second active material of the buffer layer and the second volume average particle size DE2 of the second solid electrolyte can be greater than 1.2. For example, the ratio DC2 / DE2 can be 1.3, 1.5, 2.0, 2.5, 3.0, 3.5, or even greater. The ratio DC1 / DE1 can also be any value within the aforementioned numerical range, such as 1.5, 2.0, 3.33, or even greater. Regarding the solid electrolyte layer, the ratio DE3 / DE1 of the third volume average particle size DE3 of the third solid electrolyte to the first average particle size DE1 of the first solid electrolyte can be greater than 1.2. The ratio DC1 / DE1 can also be any value greater than 1.2, such as 1.67. By selecting the particle size of each component, the mechanical strength and ionic conductivity of the positive electrode sheet, buffer layer, and solid electrolyte layer can be improved / optimized, thereby improving the structural stability and electrical performance of the battery.

[0038] In some embodiments, the positive electrode sheet may further include a first conductive agent and a first binder, the buffer layer may further include a second conductive agent and a second binder, and the solid electrolyte layer may further include a third binder. The conductive agent may be one or more selected from metal conductive agents, carbon-based conductive agents, inorganic crystalline conductive agents, polymer conductive agents, and the like. Exemplary metal conductive agents include metal powders (such as aluminum powder and nickel powder), metal fibers, or metal compound fibers. Exemplary carbon-based conductive agents include graphene, carbon nanofibers (VGCFs), carbon nanotubes (including single-walled carbon nanotubes (SWCNTs) and multi-walled carbon nanotubes (MWCNTs)), carbon black (such as acetylene black), and amorphous carbon. Exemplary inorganic crystalline conductive agents include oxide conductive agents such as lithium oxide, aluminum oxide, and magnesium oxide; sulfide conductive agents such as lithium sulfide and germanium sulfide; phosphate conductive agents such as lithium phosphate; and fluoride conductive agents such as lithium fluoride. Exemplary polymer conductive agents may include polyethylene oxide (PEO), polyvinylidene fluoride (PVDF), polyaniline (PANI), polypyrrole (PPY), polythiophene (PT), poly(3,4-ethylenedioxythiophene):polystyrene sulfonate (PEDOT:PSS), polyacrylonitrile (PAN), and the like. Alternatively, any known or commercially available conductive agent may be suitable for use in this application. The first and second conductive agents may be selected from one or more of the aforementioned examples. The first and second conductive agents may be the same or different.

[0039] Any known binder includes but is not limited to polyvinylidene fluoride, polytetrafluoroethylene, polyethylene, polypropylene, aramid resin, polyamide, polyimide, polyamideimide, polyacrylonitrile, polyacrylic acid, polymethyl acrylate, polyethyl acrylate, polyhexyl acrylate, polymethacrylic acid, polymethyl methacrylate, polyethyl methacrylate, polyhexyl methacrylate, polyvinyl acetate, polyvinyl pyrrolidone, polyether, polyether sulfone, polyhexafluoropropylene, styrene-butadiene rubber, carboxymethyl cellulose, etc. or its arbitrary combination can be used for this application. Copolymer can also be used as binder, and exemplary can be selected from tetrafluoroethylene, hexafluoroethylene, hexafluoropropylene, perfluoroalkyl vinyl ether, vinylidene fluoride, chlorotrifluoroethylene, ethylene, propylene, pentafluoropropylene, fluoromethyl vinyl ether, acrylic acid, hexadiene, etc. two or more materials copolymer. Or, the mixture of two or more materials in the above examples can also be used as binder. Including the first binder, the second binder and the third binder can each be selected from one or more of the above examples. The above three can also be the same or different.

[0040] The positive electrode sheet also includes a current collector that collects and conducts electrons. The positive electrode sheet can be obtained by combining the positive electrode film made of the above materials with the current collector through a composite press. The current collector can be made of, for example, aluminum foil, nickel foil, or stainless steel foil.

[0041] The negative electrode plate can be a metal plate or an alloy plate, such as a lithium metal plate or an alloy plate of lithium, tin, aluminum, germanium, indium, or other metals. The negative electrode plate can also be a silicon-based negative electrode plate, a carbon-based negative electrode plate, a metal oxide negative electrode plate, a composite material negative electrode plate, or the like. Alternatively, the negative electrode plate can be prepared using a solid electrolyte, such as one or more of the aforementioned solid electrolytes combined with an active material, or a mixture thereof with lithium metal, silicon, graphite, or the like. This application does not limit the choice of the negative electrode plate.

[0042] It should be noted that the above examples of the various components constituting the battery are for illustrative purposes only and are not intended to limit the scope of protection of the technical solution of this application. Any adhesive obtained by adjustment, modification, or update without violating the inventive concept of this application is within the scope of protection of this application.

[0043] The components of the battery can be in the form of layers, films, or blocks, and finally stacked together to form the battery. The thickness of the buffer layer can be Alternatively or preferably, the thickness of the buffer layer may be Alternatively or preferably, the thickness of the buffer layer may be Alternatively or preferably, the thickness of the buffer layer may be Alternatively, the thickness of the buffer layer can be any value within the above numerical range, for example 、 、 In addition, the thickness of the buffer layer (denoted as T2) should be no less than 5% of the thickness of the positive electrode sheet (denoted as T1) and no more than 60% of the thickness of the solid electrolyte layer (denoted as T3). In other words, 5%T1≤T2≤60%T3. Setting an appropriate buffer layer thickness can prevent the battery from being ineffective due to being too thin, and from having reduced energy density and electrical performance due to being too thick.

[0044] The various components of the battery can be prepared using known methods, including but not limited to wet coating, dry pressing, 3D printing, solution casting, thin film deposition, and colloidal electrospinning. The buffer layer can be formed as a composite with the positive electrode sheet or solid electrolyte layer, or it can be formed separately. For example, the raw materials for preparing the buffer layer (including proportionally weighed active materials, solid electrolytes, conductive agents, binders, etc.) can be mixed in a solvent to form a slurry, which is then evenly coated onto the already formed positive electrode sheet or solid electrolyte layer. After drying, the solvent is removed and the material is compacted to obtain a composite of the buffer layer and the positive electrode sheet or solid electrolyte layer. For another example, the raw materials can be mixed in a mixer, and after uniform mixing, they are pressed, such as by direct pressing, hot pressing, extrusion, or roller pressing, to obtain a separate buffer layer. Subsequently, the buffer layer is pressed together with the positive electrode sheet, solid electrolyte layer, and negative electrode sheet to obtain the battery.

[0045] The present application is further described in detail below with reference to the following examples. It should be noted that the following examples are only used to illustrate the present application and are not intended to limit the scope of protection claimed in the present application.

[0046] Example 1 - Preparation of a battery

[0047] 1) Preparation of positive electrode sheet:

[0048] The NCM811 positive electrode, Li2ZrCl6, and VGCF conductive agent were weighed in a ratio of 70:28:1.5 and placed in a small high-speed mixer for mixing for ~30 minutes. 0.5% PTFE adhesive was then added and continued to mix at high speed for ~10 minutes for mixing and pre-fiberization. The mixture was taken out and poured into a differential roller for film formation and thinning to the target thickness. It was then composited with aluminum foil and pressed to obtain a positive electrode sheet.

[0049] 2) Preparation of buffer layer:

[0050] The NCM811 positive electrode, Li2ZrCl6, and VGCF conductive agent were weighed in a ratio of 38:60:1.5 and then placed in a small high-speed mixer for mixing for ~30 minutes. Then, 0.5% PTFE adhesive was added and continued to mix at high speed for ~10 minutes for mixing and pre-fiberization. The mixture was taken out and poured into a differential roller for film formation and thinned to the target thickness, thereby obtaining a buffer layer;

[0051] 3) Preparation of the solid electrolyte membrane: Li6PS5Cl and PTFE binder were weighed in a 99:1 ratio and placed in a small high-speed mixer for shear mixing. After uniform mixing, the mixture was removed and repeatedly ground in a mortar until it formed a dough (lump). The dough mixture was rolled multiple times on a differential roller press at a roller temperature of 80°C and a speed ratio of 3:1 to obtain a dry-process sulfide electrolyte membrane of the target thickness.

[0052] 4) Preparation of negative electrode sheet: Li and In sheets are composite pressed at a mass ratio of 1:30 to form LiIn alloy sheet;

[0053] 5) Battery assembly: Cut the above-mentioned composite positive electrode sheet, buffer layer, electrolyte membrane, and negative electrode sheet into pieces according to the battery model of 20×20mm, and stack them in the order of negative electrode sheet-solid electrolyte membrane-buffer layer-positive electrode sheet. Then put them into aluminum-plastic film for vacuum packaging. Finally, put the packaged battery into an isostatic press for pressing at a pressure of 500MPa.

[0054] Example 2 - Preparation of a battery

[0055] Compared with Example 1, Example 2 differs in that the thickness of the prepared buffer layer is different.

[0056] Example 3 - Preparation of batteries

[0057] Compared with Example 1 and Example 2, Example 3 differs in that the thickness of the prepared buffer layer is different.

[0058] Example 4 - Preparation of a battery

[0059] Compared with Example 1, Example 4 differs in that the particle size of the solid electrolyte constituting the buffer layer is different.

[0060] Example 5 - Preparation of batteries

[0061] Compared with Example 1, Example 5 differs in that the particle size of the solid electrolyte constituting the buffer layer and the particle size of the active material are different.

[0062] Example 6 - Preparation of batteries

[0063] Compared with Example 5, Example 6 differs in that the proportion of the solid electrolyte in the positive electrode plate is different.

[0064] Example 7 - Preparation of a battery

[0065] The difference between Example 7 and Example 5 is that the proportion of the solid electrolyte in the buffer layer is different.

[0066] Example 8 - Preparation of a battery

[0067] The difference between Example 7 and Example 5 is that the proportion of the solid electrolyte in the buffer layer is different.

[0068] Comparative Example 1 - Preparation of a Battery

[0069] Compared with Example 1, Comparative Example 1 differs in that no buffer layer is added.

[0070] Table 1 and Table 2 show the relevant parameters of the above examples and comparative examples.

[0071] Table 1 Particle size and thickness parameters

[0072]

[0073] Table 2 Mass proportion, mass ratio and particle size ratio

[0074]

[0075] Example 9 - Battery Cycling Performance Test

[0076] Take the embodiment The batteries obtained in Comparative Example 1 were connected to a blue-electric test cabinet for charge and discharge testing at a temperature of 55°C and a voltage range of 2.0-3.65V. The charge and discharge rate was 0.1C for the first cycle, and 0.3C from the second cycle onward. After 50 cycles, the discharge capacity at the 50th cycle was divided by the discharge capacity at the second cycle to obtain the cycle capacity retention rate. The test results are summarized in Table 3.

[0077] Example 10 - Energy Density VED Calculation

[0078] Based on the example The first-cycle charge and discharge results of the battery obtained in Comparative Example 1 were measured using a blue light test. The energy value of the first discharge cycle was read as E on the blue light tester. The volume of the portion of the single-layer soft-pack battery excluding the aluminum-plastic film package was measured as V, and VED was calculated as E / V. The calculation structure is summarized in Table 3.

[0079] Table 3 Energy density and cycle retention rate

[0080]

[0081] As can be seen from Table 3, compared to Comparative Example 1, the batteries in Examples 1-8, by adding a buffer layer between the positive electrode sheet and the solid electrolyte layer, increased the battery's energy density and cycle capacity retention by nearly 10%. The use of a buffer layer in the batteries provided herein not only ensures high battery energy density but also achieves excellent electrical performance.

[0082] While the basic concepts have been described herein, it will be apparent to those skilled in the art that the detailed disclosure herein is merely illustrative and does not constitute a limitation of the present application. Although not expressly provided herein, those skilled in the art may make various modifications, improvements, and amendments to the present application. Such modifications, improvements, and amendments are suggested herein and remain within the spirit and scope of the exemplary embodiments of the present application.

[0083] At the same time, this application uses specific terms to describe the embodiments of this application. For example, "one embodiment," "an embodiment," and / or "some embodiments" refer to a certain feature, structure, or characteristic related to at least one embodiment of this application. Therefore, it should be emphasized and noted that "one embodiment," "an embodiment," or "an alternative embodiment" mentioned twice or multiple times in different locations in this application does not necessarily refer to the same embodiment. In addition, certain features, structures, or characteristics in one or more embodiments of this application may be appropriately combined.

[0084] Similarly, it should be noted that, in order to simplify the description of this application and thus facilitate understanding of one or more embodiments of the invention, the foregoing descriptions of the embodiments of this application sometimes combine multiple features into a single embodiment or its description. However, this disclosure method does not mean that the subject matter of this application requires more features than those recited in the claims. In fact, the features of an embodiment may be fewer than all the features of the individual embodiments disclosed above.

[0085] Finally, it should be understood that the embodiments described in this application are merely illustrative of the principles of the embodiments of this application. Other variations may also fall within the scope of this application. Therefore, by way of example and not limitation, alternative configurations of the embodiments of this application may be considered consistent with the teachings of this application. Accordingly, the embodiments of this application are not limited to the embodiments explicitly introduced and described in this application.

Claims

1. A battery, characterized in that: The battery is assembled by stacking the positive electrode sheet, the buffer layer, the solid electrolyte layer, and the negative electrode sheet in sequence; wherein, The positive electrode plate includes a first active material and a first solid electrolyte; The buffer layer includes a second active material and a second solid electrolyte; A first mass proportion of the first solid electrolyte in the total amount of the first active material and the first solid electrolyte does not exceed 40%, a second mass proportion of the second solid electrolyte in the total amount of the second active material and the second solid electrolyte is 50%-80%, and a ratio of the second mass proportion to the first mass proportion is greater than 1.6; The thickness of the buffer layer is not less than 5% of the thickness of the positive electrode sheet and not more than 60% of the thickness of the solid electrolyte layer.

2. The battery according to claim 1, characterized in that The solid electrolyte layer includes a third solid electrolyte; The first volume average particle size of the first solid electrolyte does not exceed the second volume average particle size of the second solid electrolyte; and the second volume average particle size does not exceed the third volume average particle size of the third solid electrolyte.

3. The battery according to claim 2, characterized in that A ratio of the third volume average particle diameter to the first volume average particle diameter is greater than 1.

2.

4. The battery according to claim 2, characterized in that The first active material and the second active material are the same as or different from each other; the first solid electrolyte, the second solid electrolyte, and the third solid electrolyte are the same as or different from each other.

5. The battery according to claim 1, characterized in that A fourth volume average particle size of the first active material is not smaller than a fifth volume average particle size of the second active material.

6. The battery according to claim 1, characterized in that The thickness of the buffer layer is .

7. The battery according to claim 1, characterized in that A ratio of a fourth volume average particle size of the first active material to a first volume average particle size of the first solid electrolyte is greater than 2.

8. The battery according to claim 1, characterized in that A ratio of a fifth volume average particle size of the second active material to a second volume average particle size of the second solid electrolyte is greater than 1.

2.

9. The battery according to claim 1, characterized in that The positive electrode plate also includes a first conductive agent and a first binder, the buffer layer also includes a second conductive agent and a second binder, and the solid electrolyte layer includes a third binder; wherein the first conductive agent is the same as or different from the second conductive agent, and the first binder, the second binder, and the third binder are the same as or different.

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