A solid-state pouch cell and its preparation method

Abstract

This invention belongs to the field of solid-state batteries and relates to a solid-state pouch battery and its preparation method. The solid-state pouch battery includes a rate-capable solid-state battery electrode and a polymer-based sulfide electrolyte layer. The rate-capable solid-state battery electrode includes a positive electrode material layer, a negative electrode material layer, and a porous composite current collector. The porous composite current collector includes a positive current collector and a negative current collector, both of which have through-holes. By filling the through-holes in the positive and negative current collectors with electrolyte material, it plays a role in conducting lithium ions. The composite porous design allows the Li-ion content of the positive and negative electrode material layers to increase. + The effective Li can be transferred through the electrolyte within the current collector holes of the positive and negative electrodes. + The reduced transmission distance lowers the diffusion limitations of solid-state batteries, improves their rate performance, and solves the problem of poor rate performance caused by slow lithium-ion diffusion between the positive and negative electrodes in existing sulfide all-solid-state batteries.

Description

Technical Field

[0001] This invention belongs to the field of solid-state batteries and relates to a solid-state pouch battery and its preparation method. Background Technology

[0002] Solid-state lithium batteries typically contain positive and negative electrode materials, conductive agents, and electrolytes, which are connected into electrode sheets by polymer binders. Sulfide solid electrolytes have the advantages of high ionic conductivity and good flexibility, making them one of the best solid-state electrolyte materials currently available.

[0003] However, the contact interface between the positive electrode powder, carbon-based conductive agent, and electrolyte in the electrode sheet is often a point-to-point contact. After being coated onto the current collector, the forces between the powder particles in the positive electrode coating require a binder to maintain, leading to excessive internal resistance in the electrode sheet and the entire battery. Compared to liquid batteries, all components in a solid-state battery have solid-solid contact, resulting in slower lithium-ion transport, especially for thick electrodes with high energy density. Limited lithium-ion diffusion leads to poor rate performance and long charging times, limiting the practicality of solid-state batteries. Diffusion limitation is a key factor hindering rate performance in solid-state batteries. Reducing electrode thickness can improve rate performance to some extent, but it lowers the battery's energy density and increases range anxiety for car owners.

[0004] Therefore, a new type of battery electrode is needed to solve the problem of poor lithium-ion transport in existing solid-state batteries. Summary of the Invention

[0005] The present invention aims to provide a solid-state pouch battery and its preparation method. By filling the pores penetrating the positive and negative current collectors with electrolyte material, it plays a role in conducting lithium ions. The composite porous design allows Li... + It can pass through both positive and negative current collectors simultaneously, thereby effectively converting Li into Li + The reduced transmission distance lowers the diffusion limitations of solid-state batteries, improves their rate performance, and solves the problem of poor rate performance caused by slow lithium-ion diffusion between the positive and negative electrodes in existing sulfide all-solid-state batteries.

[0006] In a first aspect, the present invention provides a solid-state pouch battery, comprising a high-rate solid-state battery electrode and a polymer-based sulfide electrolyte layer, wherein the high-rate solid-state battery electrode comprises:

[0007] Positive electrode material layer;

[0008] Negative electrode material layer;

[0009] A porous composite current collector includes an overlapping positive current collector and a negative current collector, both having through holes; a positive electrode material layer is disposed on the side of the positive current collector away from the negative current collector, and a negative electrode material layer is disposed on the side of the negative current collector away from the positive current collector.

[0010] In this embodiment, the electrolyte material fills the pores penetrating the positive and negative electrode current collectors, serving to conduct lithium ions. This composite porous design enables Li... + It can pass through both positive and negative current collectors simultaneously, thereby effectively converting Li into Li + The shortened transmission distance reduces the diffusion limitations of solid-state batteries and improves their rate performance.

[0011] In some embodiments, the diameter of the holes on the positive current collector and the negative current collector is 1-500 μm, and the hole spacing is 750-800 μm;

[0012] Preferably, the positive current collector is stainless steel foil, aluminum foil, or carbon-coated aluminum foil, and the negative current collector is carbon-coated copper foil or stainless steel foil.

[0013] The diameter of the holes on the positive and negative current collectors is 1-500um, and the hole spacing is 750-800um, which can maximize the lithium-ion conduction function, reduce the transmission distance, and at the same time ensure the mechanical strength of the positive and negative current collectors.

[0014] In some embodiments, the positive electrode material layer is obtained by drying a positive electrode slurry layer, wherein the positive electrode slurry includes a positive electrode active material, a sulfide electrolyte, a binder, and a conductive agent;

[0015] Preferably, the positive electrode slurry has a solid content of 50-65%;

[0016] Preferably, the weight ratio of the positive electrode active material, sulfide electrolyte, binder, and conductive agent in the positive electrode slurry layer is (75-85):(12-20):(2-4):(1-2);

[0017] Preferably, the positive electrode active material is one or more of the following: lithium niobate or alumina-coated lithium cobalt oxide, lithium nickel oxide, lithium manganese oxide, lithium manganese oxide, lithium nickel manganese oxide, lithium-rich manganese-based oxide, lithium manganese iron phosphate, lithium nickel cobalt aluminum oxide, lithium nickel cobalt manganese oxide, lithium iron phosphate, and lithium vanadium phosphate.

[0018] Preferably, the conductive agent is one or more of vapor-grown carbon fibers, carbon nanotubes, and multi-walled carbon nanotubes;

[0019] Preferably, the negative electrode material layer is obtained by drying a negative electrode slurry, wherein the negative electrode slurry includes a negative electrode active material, a sulfide electrolyte, a binder, and a conductive agent;

[0020] Preferably, the negative electrode slurry has a solid content of 45-60%;

[0021] Preferably, the weight ratio of negative electrode active material, sulfide electrolyte, binder and conductive agent in the negative electrode slurry layer is 70-90):(7-25):(2-4):(1-2);

[0022] Preferably, the negative electrode active material is at least one of micron-sized silicon, nano-sized silicon, silicon suboxide, and homogeneous silicon carbon;

[0023] Preferably, the adhesive comprises at least one of fluoropolymer, styrene-butadiene-styrene triblock copolymer, hydrogenated styrene-butadiene-styrene triblock copolymer, hydrogenated nitrile rubber, nitrile rubber, SEBS, polymethyl methacrylate, and polyethylene oxide;

[0024] Preferably, the sulfide electrolyte is one or more of LGPS, LPS, Li6PS5X, and LiSiPSX; wherein, in Li6PS5X, LiSiPSX, and LiSiPSX, X is selected from at least one of F, Cl, Br, and I.

[0025] The positive and negative electrode material layers composed of the materials in the above ratio have high capacity utilization and good electrode condition.

[0026] In some embodiments, the porous composite current collector further includes a polymer-based sulfide electrolyte layer, which comprises a porous insulating polymer substrate and an electrolyte layer coated thereon, wherein the porous insulating polymer substrate has through-holes.

[0027] Preferably, the pore diameter of the porous insulating polymer substrate is 1-1000 μm;

[0028] Preferably, the porous insulating polymer substrate is at least one of PET, PVDF, and PTFE.

[0029] Preferably, the electrolyte layer comprises a binder and a sulfide electrolyte;

[0030] Preferably, the adhesive comprises at least one of fluoropolymer, styrene-butadiene-styrene triblock copolymer, hydrogenated styrene-butadiene-styrene triblock copolymer, hydrogenated nitrile rubber, nitrile rubber, SEBS, polymethyl methacrylate, and polyethylene oxide;

[0031] Preferably, the sulfide electrolyte is one or more of LGPS, LPS, Li6PS5X, and LiSiPSX; wherein, in Li6PS5X, LiSiPSX, and LiSiPSX, X is selected from at least one of F, Cl, Br, and I.

[0032] Through composite porous design, Li + It can simultaneously pass through the positive and negative electrode current collectors and the sulfide solid electrolyte membrane, thereby effectively transferring Li + The transmission distance is halved, further reducing diffusion limitations and improving the rate performance of solid-state batteries.

[0033] In some embodiments, the rate-capable solid-state battery electrode has n+1 layers, the polymer-based sulfide electrolyte layer has n layers, the n+1 layers of the rate-capable solid-state battery electrode and the n layers of the polymer-based sulfide electrolyte layer are stacked alternately, and the polymer-based sulfide electrolyte layer is disposed between the intervals formed by adjacent stacks of the rate-capable solid-state battery electrode, wherein n is greater than or equal to 1.

[0034] In some implementations, the areal capacity of the outermost positive electrode material layer of the solid-state pouch battery is 0.4-0.6 times that of the areal capacity of the middle positive electrode material layer; the areal capacity of the outermost negative electrode material layer of the solid-state pouch battery is 0.4-0.6 times that of the middle negative electrode material layer.

[0035] Preferably, the areal capacity of the positive electrode material layer located in the middle of the solid-state pouch battery is 3-5 mAh / cm². 2 The areal capacity of the outermost positive electrode material layer of the solid-state pouch battery is 1.5-2.5 mAh / cm². 2 The areal capacity of the negative electrode material layer located in the middle of the solid-state pouch battery is 3.3-5.5 mAh / cm². 2 The areal capacity of the negative electrode material layer located on the outermost side of the solid-state pouch battery is 1.65-2.75 mAh / cm². 2 .

[0036] In this implementation plan, the battery capacity is more appropriately matched, making it less likely to overcharge or over-discharge.

[0037] In a second aspect, the present invention provides a method for preparing a solid-state pouch cell, comprising the following steps:

[0038] (1) Die-cut the high-rate solid-state battery electrode and the polymer-based sulfide electrolyte layer respectively;

[0039] (2) Three-layer high-rate solid-state battery electrode and two-layer polymer-based sulfide electrolyte layer are stacked alternately, and the two-layer polymer-based sulfide electrolyte layer is respectively set between the gaps formed by the stacking of three-layer high-rate solid-state battery electrode to obtain a high-rate solid-state soft pack battery.

[0040] In some embodiments, the method for preparing the rate-adjustable solid-state battery electrode is as follows:

[0041] A positive electrode slurry is coated on the side of the positive electrode current collector away from the negative electrode current collector to form the positive electrode material layer, and a negative electrode slurry is coated on the side of the negative electrode current collector away from the positive electrode current collector to form the negative electrode material layer. After drying, a high-rate solid-state battery electrode sheet is obtained.

[0042] Preferably, the porous composite current collector is prepared by: punching holes in the positive electrode current collector and the negative electrode current collector, and then setting them on both sides of the polymer-based sulfide solid electrolyte layer, followed by static pressure.

[0043] In the prepared rate-capable solid electrolyte electrode, lithium ions have two transport directions. Both the porous composite current collector and the polymer-based sulfide electrolyte layer can conduct lithium ions, which is equivalent to shortening the transport path of lithium ions, reducing the diffusion restriction of lithium ions in the electrode, and thus improving the rate performance of the battery.

[0044] The positive current collector and the negative current collector, which are set on both sides of the polymer-based sulfide solid electrolyte layer, are subjected to static pressure at 200-400MPa, so that the three become a whole. Part of the electrolyte material in the polymer-based sulfide solid electrolyte layer fills the pores of the positive current collector and the negative current collector on both sides to form an ion channel.

[0045] In some embodiments, the polymer-based sulfide electrolyte layer is prepared by:

[0046] The adhesive is dissolved in an organic solvent to obtain a slurry; a sulfide electrolyte is added to the slurry and mixed to obtain an electrolyte slurry; the electrolyte slurry is coated onto a porous insulating polymer substrate to obtain a polymer-based sulfide electrolyte layer.

[0047] In some embodiments, the method for preparing the positive electrode slurry is as follows:

[0048] The binder is dissolved in a solvent to obtain a glue solution. The positive electrode active material, conductive agent, and sulfide electrolyte are added to the glue solution and mixed well to obtain the positive electrode slurry.

[0049] Preferably, the negative electrode slurry preparation method is as follows: adding negative electrode active material and sulfide electrolyte to the adhesive solution, mixing well, and obtaining negative electrode slurry.

[0050] In summary, this application includes at least one of the following beneficial technical effects:

[0051] Electrolyte material is filled into the pores penetrating the positive and negative electrode current collectors to conduct lithium ions. This composite porous design allows Li... + It can pass through both positive and negative current collectors simultaneously, thereby effectively converting Li into Li + The shortened transmission distance reduces the diffusion limitations of solid-state batteries and improves their rate performance. Attached Figure Description

[0052] Figure 1 This is a schematic diagram of the solid-state pouch battery in this invention.

[0053] Reference numerals: 1. Rate-capable solid-state battery electrode; 2. Polymer-based sulfide electrolyte layer; 11. Porous composite current collector; 111. Positive current collector; 112. Negative current collector; 113. Second polymer-based sulfide solid electrolyte layer; 12. Positive slurry layer; 13. Negative slurry layer. Detailed Implementation

[0054] The following specific embodiments further illustrate the technical solution of the present invention. These specific embodiments do not represent a limitation on the scope of protection of the present invention. Non-essential modifications and adjustments made by others based on the concept of the present invention still fall within the scope of protection of the present invention.

[0055] Example 1

[0056] A method for preparing a solid-state pouch cell includes the following steps:

[0057] 1. Preparation of polymer-based sulfide electrolyte layer

[0058] (1) Dissolve the adhesive fluoropolymer EY in the organic solvent isobutyl isobutyrate to obtain the adhesive solution;

[0059] In other embodiments, the fluoropolymer EY adhesive can also be replaced by other adhesives such as styrene-butadiene-styrene triblock copolymer, hydrogenated styrene-butadiene-styrene triblock copolymer, hydrogenated nitrile rubber, nitrile rubber, SEBS, polymethyl methacrylate, polyethylene oxide, nitrile rubber, hydrogenated nitrile rubber, styrene-butadiene-styrene block copolymer, or a mixture of at least two of these, which can increase the overall mechanical strength of the polymer-based sulfide electrolyte layer;

[0060] The organic solvent polymer isobutyl isobutyrate can also be replaced with other organic solvents such as toluene, xylene, anisole, isobutyl isobutyrate, butyl butyrate, hexyl butyrate, n-heptane or a mixture of at least two of them, to facilitate uniform dispersion of the adhesive and sulfide electrolyte.

[0061] (2) Add the sulfide electrolyte Li6PS5Cl to the gel solution and ball mill at 300 rpm for 30 min to obtain the electrolyte slurry;

[0062] In this embodiment, the solid content of the obtained electrolyte slurry is 55%, wherein the mass ratio of the sulfide electrolyte Li6PS5Cl to the binder fluoropolymer EY is m(Li6PS5Cl):m(EY)=97:3, and the solid content of the slurry is 53%.

[0063] In other embodiments, the sulfide electrolyte Li6PS5Cl can also be replaced with at least one of LGPS, LPS, Li6PS5X, LiSiPSX, or Li2SP2S5, Li 10 GeP2S 12 Li 10 SnP2S 12 The mixture contains at least one or a mixture of at least two common sulfide electrolytes, wherein X is selected from at least one of F, Cl, Br, or I; the ball milling time and speed can also be adjusted as needed, with the ball milling speed ranging from 100-350 r / min, such as 350 rpm for 20 min, 250 rpm for 35 min, etc. Other mixing methods such as grinding can also be used, as long as the sulfide electrolyte and adhesive are mixed evenly; in other embodiments, the solid content of the obtained electrolyte slurry can also be adjusted as needed, such as 50%, 52%, 55%, 58%, 60%, etc., and the mass ratio of the sulfide electrolyte Li6PS5Cl to the adhesive fluoropolymer EY can also be adjusted to a suitable ratio such as 95:5, 96:4, 98:2, etc.

[0064] (3) The electrolyte slurry is coated onto a porous insulating polymer substrate PET (polyethylene terephthalate) film with a pore size of 100 μm and dried at 70 °C to obtain a polymer-based sulfide electrolyte layer.

[0065] In other embodiments, the PET film can also be a porous insulating polymer substrate made of PVDF (polyvinylidene fluoride) or PTFE (Teflon), and the pore size of the porous insulating polymer substrate can be any size from 100-1000 μm, such as 110 μm, 120 μm, 125 μm, 134 μm, 156 μm, 570 μm, 600 μm, 700 μm, 750 μm, 800 μm, 900 μm, 1000 μm, etc. This maximizes the lithium-ion conduction effect while ensuring the flexibility and mechanical strength of the electrolyte membrane.

[0066] 2. Preparation of porous composite current collectors

[0067] (1) Aluminum foil for positive current collector and stainless steel foil for negative current collector are perforated with a diameter of 100 μm and a spacing of 800 μm to obtain porous aluminum foil and porous stainless steel foil.

[0068] In other embodiments, the positive current collector can also be a metal current collector such as stainless steel foil, aluminum foil, or carbon-coated aluminum foil, and similarly, the negative current collector can also be a metal current collector such as carbon-coated copper foil or stainless steel foil; the diameter of the hole can also be any size in the range of 100-500um, such as 110um, 120um, 125um, 134um, 356um, 470um, 500um, etc., and the hole spacing can also be 750um, 780um, 800um, 830um, 850um, etc.

[0069] (2) Porous aluminum foil and porous stainless steel foil are respectively bonded to both sides of the polymer-based sulfide solid electrolyte layer, and the three are made into a whole under a static pressure of 300MPa to obtain a porous composite current collector.

[0070] In this embodiment, under pressure, some electrolyte material fills the pores of the foils on both sides to form an ion pathway.

[0071] In other embodiments, the static pressure can also be other values ​​greater than or less than 300 MPa, such as 200 MPa, 250 MPa, 380 MPa, 400 MPa, etc., as long as the porous aluminum foil, porous stainless steel foil, and polymer-based sulfide solid electrolyte layer can be integrated into a whole, and the electrolyte material can fill the pores of the foils on both sides to form an ion channel.

[0072] 3. Rate-type solid-state battery electrode sheets

[0073] (1) Dissolve the binder fluororubber EY in the solvent isobutyl isobutyrate to obtain a glue solution. Add the positive electrode active material NCM83, the conductive agent VGCF, and the sulfide electrolyte Li6PS5Cl to the glue solution and ball mill at 300 rpm for 60 min to obtain the positive electrode slurry.

[0074] In this embodiment, m(NCM83):m(Li6PS5Cl):m(EY):m(VGCF) = 85:15:2.5:1.5, and the slurry solid content is 55%.

[0075] In other embodiments, the positive electrode active material can also be replaced by one or more of lithium niobate, alumina-coated lithium cobalt oxide, lithium nickel oxide, lithium manganese oxide, lithium manganese oxide, lithium nickel manganese oxide, lithium-rich manganese-based, lithium manganese iron phosphate, lithium nickel cobalt aluminum oxide, lithium nickel cobalt manganese oxide, lithium iron phosphate, and lithium vanadium phosphate; the conductive agent can also be replaced by one or more of vapor-grown carbon fibers, carbon nanotubes, and multi-walled carbon nanotubes; the solid content of the positive electrode slurry can also be adjusted as needed, such as 50%, 55%, 56%, 57%, 58%, and 60%; the mass ratio of the positive electrode active material, sulfide electrolyte, binder, and conductive agent can also be adjusted to any ratio within the range of (75-85):(12-20):(2-4):(1-2), such as a suitable ratio of 80:16:3:1.

[0076] (2) Dissolve the binder fluororubber EY in isobutyl isobutyrate to obtain a glue solution. Add the anode active material homogeneous silicon carbon and sulfide electrolyte Li6PS5Cl to the glue solution and ball mill at 300 rpm for 60 min to obtain the anode slurry.

[0077] In this embodiment, m(homogeneous silicon carbide):m(Li6PS5Cl):m(EY):m(VGCF) = 77:20:2:1, and the slurry solid content is 50%.

[0078] In other embodiments of the present invention, the homogeneous silicon-carbon anode active material can be replaced with silicon materials such as micron-sized silicon, nano-sized silicon, and silicon suboxide with equivalent function. The solid content of the anode slurry can also be adjusted as needed, such as 50%, 58%, 60%, etc. The mass ratio of the anode active material to the sulfide electrolyte, binder, and conductive agent can also be adjusted to any ratio within the range of (70-90):(7-25):(2-4):(1-2).

[0079] (3) A positive electrode slurry is coated on the porous aluminum foil side of the porous composite current collector and dried at 80°C to form a positive electrode material layer; a negative electrode slurry is coated on the porous stainless steel foil side of the porous composite current collector and dried at 80°C to form a negative electrode material layer, thus obtaining a rate-type solid-state battery electrode.

[0080] In other embodiments of the present invention, all drying temperatures can be any temperature within the range of 60-90℃, such as 65℃, 73℃, 85℃, 90℃, etc. Similarly, in other embodiments of the present invention, the time and speed of ball milling of the rubber compound in each step can also be adjusted as needed. The ball milling speed can be taken in the range of 100-350 r / min, such as 350 rpm for 20 min, 250 rpm for 35 min, 150 rpm for 60 min, etc. Other mixing methods such as grinding can also be used, as long as the different components can be mixed evenly.

[0081] Similarly, in other embodiments, all fluoropolymer EY adhesives involved in this invention can be replaced by other adhesives such as styrene-butadiene-styrene triblock copolymer, hydrogenated styrene-butadiene-styrene triblock copolymer, hydrogenated nitrile rubber, nitrile rubber, SEBS, polymethyl methacrylate, polyethylene oxide, nitrile rubber, hydrogenated nitrile rubber, styrene-butadiene-styrene block copolymer, or mixtures of at least two of these; the organic solvent polymer isobutyl isobutyrate can also be replaced by other organic solvents such as toluene, xylene, anisole, isobutyl isobutyrate, butyl butyrate, hexyl butyrate, n-heptane, or mixtures of at least two of these; the sulfide electrolyte can be replaced by at least one of LGPS, LPS, Li6PS5X, LiSiPSX, or Li2SP2S5, Li 10 GeP2S 12 Li 10 SnP2S 12 X is selected from at least one of common sulfide electrolytes or a mixture of at least two of them, wherein X is selected from at least one of F, Cl, Br or I.

[0082] 4. Preparation of solid-state pouch cells

[0083] (1) The high-rate solid-state battery electrode and the polymer-based sulfide electrolyte layer are respectively die-cut to a size of 9.6*12.6cm. The area of ​​the positive electrode material region (i.e., the region formed after the positive electrode slurry layer is dried) in the battery electrode is controlled to be 9.3*12.3cm, and the area of ​​the negative electrode material region (i.e., the region formed after the negative electrode slurry layer is dried) is controlled to be 9.6*12.6cm.

[0084] In other embodiments, the die-cut area can also be adjusted according to the battery model and size.

[0085] (2) Three-layer high-rate solid-state battery electrode and two-layer polymer-based sulfide electrolyte layer are stacked alternately. The two-layer polymer-based sulfide electrolyte layer is set between the gaps formed by the stacking of three-layer battery electrode, so that one side of the polymer-based electrolyte layer is the positive electrode material layer and the other side is the negative electrode material layer. The tabs are welded and subjected to 300MPa isostatic pressure for 5 minutes to obtain a high-rate solid-state soft pack battery.

[0086] In other embodiments of the present invention, the pressure and time of isostatic pressing can also be adjusted as needed, such as 200MPa isostatic pressing for 10 minutes, 350MPa isostatic pressing for 3 minutes, etc., as long as the three-layer battery electrode and the two-layer polymer-based sulfide electrolyte can be laminated together. For rate-capable solid-state pouch batteries, n+1 layers of battery electrodes and n layers of polymer-based sulfide electrolyte can be stacked alternately, with the n polymer-based sulfide electrolyte layers respectively disposed between the intervals formed by the n+1 layers of battery electrodes, such that one side of the polymer-based electrolyte layer is the positive electrode active layer (positive electrode material layer), and the other side is the negative electrode active layer (negative electrode material layer).

[0087] The specific capacity of the positive electrode material of the solid-state pouch battery prepared in this embodiment is 210 mAh / cm³. 2 The specific capacity of the negative electrode material is 1700 mAh / cm³. 2 The areal capacity of the positive material layer in the middle layer (referring to the positive electrode located inside the stacked three-layer battery electrode sheet) is 3 mAh / cm². 2 (Corresponding to a coating gap of 200µm), the capacity of the outermost positive electrode material layer is 1.5mAh / cm². 2 (Corresponding to a coating gap of 100µm). The areal capacity of the intermediate negative electrode material layer (referring to the negative electrode located inside the stacked three-layer battery electrode sheet) is 3.3mAh / cm². 2 (Corresponding to a coating gap of 100µm), the capacity of the outermost negative electrode material layer is 1.65mAh / cm². 2 (Corresponding to a coating gap of 50um). To ensure battery capacity matching and prevent overcharging and over-discharging, the areal capacity of the outermost electrode of the pouch battery is half that of the middle electrode.

[0088] Example 2

[0089] A method for preparing a solid-state pouch cell differs from Example 1 in that the areal capacity of the positive electrode material layer (the positive electrode located inside the stacked three-layer battery electrode sheet) in the middle layer of the solid-state pouch cell is 4 mA / cm². 2 (Corresponding to a coating gap of 260um), the capacity of the outermost positive electrode material layer is 2mAh / cm². 2 (Corresponding to a coating gap of 130µm). The areal capacity of the intermediate negative electrode material layer (referring to the negative electrode located inside the stacked three-layer battery electrode sheet) is 4.4mAh / cm². 2 (Corresponding to a coating gap of 130µm), the capacity of the outermost negative electrode material layer is 2.2mAh / cm². 2 (Corresponding coating gap is 65um).

[0090] Example 3

[0091] A method for preparing a solid-state pouch cell differs from Example 1 in that the areal capacity of the positive electrode material layer (the positive electrode located inside the stacked three-layer battery electrode sheet) in the middle layer of the solid-state pouch cell is 5 mA / cm². 2 (Corresponding to a coating gap of 300um), the capacity of the outermost positive electrode material layer is 2.5mAh / cm². 2 (Corresponding to a coating gap of 165um). The areal capacity of the intermediate negative electrode material layer (referring to the negative electrode located inside the stacked three-layer battery electrode sheet) is 5.5mAh / cm². 2 (Corresponding to a coating gap of 165um), the capacity of the outermost negative electrode material layer is 2.75mAh / cm². 2 (Corresponding coating gap is 85m).

[0092] like Figure 1 As shown, the solid-state pouch battery in Examples 1-3 includes a three-layer high-rate solid-state battery electrode 1 and a two-layer first polymer-based sulfide electrolyte layer 2. The three-layer high-rate solid-state battery electrode 1 and the two-layer first polymer-based sulfide electrolyte layer 2 are stacked alternately, and the two-layer first polymer-based sulfide electrolyte layer 2 are respectively disposed between the gaps formed by the three-layer high-rate solid-state battery electrode 1.

[0093] The high-rate solid-state battery electrode 1 includes a porous composite current collector 11, a positive electrode material layer 12, and a negative electrode material layer 13. The positive electrode material layer 12 is obtained by coating a positive electrode slurry on the front side of the porous composite current collector 11 and drying it. The negative electrode slurry layer 13 is obtained by coating a negative electrode slurry on the back side of the porous composite current collector 11 and then drying it at 70°C to obtain the high-rate solid-state battery electrode 1.

[0094] The porous composite current collector 11 includes a positive current collector 111, a negative current collector 112, and a second polymer-based sulfide solid electrolyte layer 113. The positive current collector 111 is an aluminum foil, and the negative current collector 112 is a stainless steel foil. Both the positive current collector 111 and the negative current collector 112 are provided with through holes with a diameter of 100 μm and a spacing of 800 μm between the through holes. The positive current collector 111 and the negative current collector 112 are respectively attached to the front and back sides of the second polymer-based sulfide solid electrolyte layer 113. The positive current collector 111 and the negative current collector 112 are fixed to the front and back sides of the second polymer-based sulfide solid electrolyte layer 113 under a static pressure of 300 MPa, so that the three become a whole to form the porous composite current collector 11.

[0095] The first polymer-based sulfide electrolyte layer 2 and the second polymer-based sulfide solid electrolyte layer 113 have the same structure, both including a porous insulating polymer substrate 21 and an electrolyte layer 22. The porous insulating polymer substrate 21 has through holes with a pore size of 100 μm. Electrolyte slurry is coated onto the porous insulating polymer substrate 21 and dried at 70°C to form the electrolyte layer 22.

[0096] During the assembly of the solid-state pouch battery, the rate-type solid-state battery electrode 1 and the first polymer-based sulfide electrolyte layer 2 are first die-cut to a size of 9.6*12.6cm. The area of ​​the positive electrode material layer 12 in the rate-type solid-state battery electrode 1 is controlled to be 9.3*12.3cm, and the area of ​​the negative electrode material layer 13 is controlled to be 9.6*12.6cm. Then, the three-layer rate-type solid-state battery electrode 1 and the two-layer first polymer-based sulfide electrolyte layer 2 are stacked alternately. The two-layer polymer-based sulfide electrolyte layer 2 are respectively placed between the gaps formed by the stacking of the three-layer rate-type solid-state battery electrode 1, so that one side of the first polymer-based sulfide electrolyte layer 2 is the negative electrode material layer 13 and the other side is the positive electrode material layer 12. The tabs are welded, and the battery is subjected to isostatic pressure of 300MPa for 5 minutes to obtain the rate-type solid-state pouch battery.

[0097] Comparative Example 1

[0098] A method for preparing a solid-state pouch cell includes the following steps:

[0099] 1. Preparation of polymer-based sulfide electrolyte layer

[0100] (1) Dissolve the fluoropolymer EY adhesive in isobutyl isobutyrate to obtain an adhesive solution;

[0101] (2) Add the sulfide electrolyte Li6PS5Cl to the colloid solution and ball mill at 300 rpm for 30 min to obtain an electrolyte slurry. The solid content of the electrolyte slurry is 55%, and the ratio of m(Li6PS5Cl):m(EY) is 97:3.

[0102] (3) The electrolyte slurry is coated onto a PET membrane with a pore size of 100-1000um and dried at 70℃ to obtain a polymer-based sulfide electrolyte layer.

[0103] 2. Preparation of traditional double-sided positive electrode plates and single-sided negative electrode plates

[0104] (1) Dissolve the binder fluororubber EY in isobutyl isobutyrate to obtain a glue solution. Add the positive electrode active material NCM83, the conductive agent VGCF, and the sulfide electrolyte Li6PS5Cl to the glue solution. Ball mill at 300 rpm for 60 min to obtain a positive electrode slurry. The solid content of the positive electrode slurry is 60%, wherein m(NCM83):m(Li6PS5Cl):m(EY):m(VGCF)=85:15:2.5:1.5;

[0105] (2) Dissolve the binder fluororubber EY in isobutyl isobutyrate to obtain a glue solution. Add the negative electrode active material homogeneous silicon carbon and sulfide electrolyte Li6PS5Cl to the glue solution and ball mill at 300rpm for 60min to obtain a negative electrode slurry. The solid content of the negative electrode slurry is 55%, and m(homogeneous silicon carbon):m(Li6PS5Cl):m(EY):m(VGCF)=77:20:2:1;

[0106] (3) The positive electrode slurry is coated onto the surface of aluminum foil and dried at 70°C. Then, the positive electrode slurry is coated onto the other side of the aluminum foil to obtain a double-sided positive electrode sheet with an areal capacity of 6 mAh / cm². 2 Similarly, the negative electrode slurry is coated onto one side of a stainless steel foil and dried at 70°C to obtain a single-sided negative electrode sheet with a single-sided negative electrode surface capacity of 3.3 mAh / cm². 2 ;

[0107] 3. Preparation of solid-state pouch cells

[0108] (1) Die-cut a double-sided positive electrode sheet, a single-sided negative electrode sheet and a polymer-based sulfide electrolyte layer. The size of the double-sided positive electrode sheet is 9.3*12.3cm, and the size of the single-sided negative electrode sheet and the polymer-based sulfide electrolyte layer is 9.6*12.6cm.

[0109] (2) Stack the single-sided negative electrode, polymer-based sulfide electrolyte layer, double-sided positive electrode, polymer-based electrolyte membrane layer and single-sided negative electrode in sequence, weld the tabs, and press the battery under isostatic pressure of 300MPa for 5 minutes to obtain a rate-type solid-state soft pack battery.

[0110] Comparative Example 2

[0111] A method for preparing a solid-state pouch cell differs from Comparative Example 1 in that the capacity of the double-sided positive electrode is 8 mA / cm². 2 The single-sided negative electrode capacity is 4.4 mAh / cm². 2 .

[0112] Comparative Example 3

[0113] A method for preparing a solid-state pouch cell differs from Comparative Example 1 in that the capacity of the double-sided positive electrode is 10 mA / cm². 2 The single-sided negative electrode capacity is 5.5mAh / cm². 2 .

[0114] Comparative Example 4

[0115] A method for preparing a solid-state pouch battery differs from Example 1 in that, during electrode preparation, the electrolyte slurry from Example 1 is directly coated onto the back of a porous aluminum foil or porous stainless steel foil. The porous aluminum foil or porous stainless steel foil with the electrolyte slurry coated on one side is then dried. The porous aluminum foil, electrolyte layer, and porous stainless steel foil are then pressed into a porous composite current collector under a pressure of 200 MPa. The electrolyte layer is located between the porous aluminum foil and the porous stainless steel foil. A positive electrode slurry is coated on the porous aluminum foil side of the porous composite current collector, and a negative electrode slurry is coated on the porous stainless steel foil side. The mixture is then dried at 70°C to obtain a rate-capable solid-state battery electrode. When assembling the solid-state pouch battery, the electrolyte slurry is directly coated onto the aluminum foil current collector and then peeled off, resulting in a polymer-free electrolyte membrane replacing the polymer-based electrolyte layer.

[0116] The result is not only a more complicated process, but also a low success rate in the step of peeling the electrolyte membrane from the aluminum foil current collector to obtain a polymer-free electrolyte membrane, increasing production costs. Furthermore, the electrolyte layer has lower mechanical strength due to the lack of a porous insulating polymer substrate, making it difficult to assemble the battery later. The polymer-free electrolyte membrane is also prone to defects during processing, leading to micro-short circuits during battery charging and discharging.

[0117] Comparative Example 5

[0118] A method for preparing a solid-state pouch cell differs from Example 1 in that the positive electrode active layer (the positive electrode located inside the stacked three-layer battery electrode sheet) of the rate-capacity solid-state pouch cell has an areal capacity of 3 mAh / cm². 2 The capacity of the outermost positive electrode active layer is 2mAh / cm³. 2 The areal capacity of the intermediate negative electrode active layer (referring to the negative electrode located inside the stacked three-layer battery electrode sheet) is 3.3 mAh / cm². 2 The capacity of the outermost negative electrode active layer is 1 mAh / cm². 2 The resulting solid-state pouch batteries exhibited overcharging and over-discharging issues.

[0119] Performance testing

[0120] 1. The battery was charged and discharged using a Xinwei test cabinet. The charge / discharge range was 2-4.25V, the test temperature was 55℃, and the test pressure was 100MPa. The test results are shown in Table 1.

[0121] Table 1. Charge and discharge test results

[0122]

[0123]

[0124] As shown in Table 1, the difference between Examples 1, 2, and 3 lies in the different areal loadings of the electrode sheets. From Example 1 to Example 3, and from Comparative Example 1 to Comparative Example 3, the rate performance of the battery gradually decreases as the areal loading of the electrode sheet increases. The difference between Example 1 and Comparative Example 1, Example 2 and Comparative Example 2, and Example 3 and Comparative Example 3 lies in the different electrode sheet structures. The battery using a rate-type solid electrolyte electrode sheet exhibits better capacity utilization and rate performance than the battery using a traditional electrode sheet. Comparative Examples 2 and 3 show that when the areal loading of the single positive electrode is greater than 4 mAh / cm², the rate performance increases. 2 At 2C, the battery experiences overcharging and short circuit. This is because in traditional electrodes, lithium ions can only be transported in one direction. In thick electrodes with high areal load, the lithium ion transport path is long and the speed is slow. Lithium ions tend to accumulate on the negative electrode surface, and the growth of dendrites leads to a short circuit. In high-rate solid electrolyte electrodes, lithium ions have two transport directions. Both the porous composite current collector and the electrolyte layer can conduct lithium ions, which is equivalent to shortening the lithium ion transport path and reducing the diffusion restriction of lithium ions in the electrode, thereby improving the rate performance of the battery.

[0125] Compared to Example 1, Comparative Example 4 removed the polymer substrate from the polymer-based electrolyte membrane. This not only resulted in a more complex battery manufacturing process, but also led to a very low success rate in the step of peeling the electrolyte membrane from the aluminum foil current collector to obtain a polymer-free electrolyte membrane, increasing production costs. Furthermore, the electrolyte layer lacked the support of a porous insulating polymer substrate, resulting in lower mechanical strength and making subsequent battery assembly difficult. The polymer-free electrolyte membrane was also prone to defects during processing, leading to micro-short circuits during charging and discharging, and consequently, lower initial battery efficiency.

[0126] Compared with Example 1, Comparative Example 5 has a negative electrode capacity to positive electrode capacity ratio of less than 1, which leads to lithium deposition on the negative electrode surface, short circuit during battery charging, and low initial efficiency.

[0127] It is understood that the present invention has been described through some embodiments, and those skilled in the art will recognize that various changes or equivalent substitutions can be made to these features and embodiments without departing from the spirit and scope of the invention. Furthermore, under the teachings of the present invention, these features and embodiments can be modified to adapt to specific situations and materials without departing from the spirit and scope of the invention. Therefore, the present invention is not limited to the specific embodiments disclosed herein, and all embodiments falling within the scope of the claims of this application are within the protection scope of the present invention.

Claims

1. A solid-state soft-pack battery, characterized by, The solid-state battery electrode sheet comprises a rate type solid-state battery electrode sheet and a polymer-based sulfide electrolyte layer, the rate type solid-state battery electrode sheet comprises: a positive electrode material layer; a negative electrode material layer; a porous composite current collector, the porous composite current collector comprises a positive electrode current collector and a negative electrode current collector arranged in an overlapping manner, and the positive electrode current collector and the negative electrode current collector have through-holes; the positive electrode material layer is arranged on the side of the positive electrode current collector away from the negative electrode current collector, and the negative electrode material layer is arranged on the side of the negative electrode current collector away from the positive electrode current collector; the porous composite current collector further comprises a polymer-based sulfide electrolyte layer, which is arranged between the positive electrode current collector and the negative electrode current collector, and comprises a porous insulating polymer substrate and an electrolyte layer coated on the surface of the porous insulating polymer substrate, and the porous insulating polymer substrate has through-holes; The rate type solid-state battery electrode sheet is arranged in n+1 layers, and the polymer-based sulfide electrolyte layer is arranged in n layers; the n+1 layers of the rate type solid-state battery electrode sheet and the n layers of the polymer-based sulfide electrolyte layer are stacked alternately, the polymer-based sulfide electrolyte layer is arranged between the intervals formed by the adjacent rate type solid-state battery electrode sheets, and n is greater than or equal to 1; the surface capacity of the positive electrode material layer located at the outermost side of the solid-state soft package battery is 0.4-0.6 times that of the positive electrode material layer located in the middle; the surface capacity of the negative electrode material layer located at the outermost side of the solid-state soft package battery is 0.4-0.6 times that of the negative electrode material layer located in the middle.

2. The solid-state soft-pack battery of claim 1, wherein, The diameter of the holes on the positive electrode current collector and the negative electrode current collector is 1-500 um, and the hole gap is 750-800 um; the positive electrode current collector is a stainless steel foil, an aluminum foil or a carbon-coated aluminum foil, and the negative electrode current collector is a carbon-coated copper foil or a stainless steel foil.

3. The solid-state soft-pack battery of claim 1, wherein, The positive electrode material layer is obtained by drying a positive electrode slurry, the positive electrode slurry comprising a positive electrode active material, a sulfide electrolyte, a binder and a conductive agent; the solid content of the positive electrode slurry is 50-65%; the weight ratio of the positive electrode active material, the sulfide electrolyte, the binder and the conductive agent in the positive electrode slurry layer is (75-85):(12-20):(2-4):(1-2); the positive electrode active material is one or more of lithium niobate or lithium cobalt oxide coated with aluminum oxide, lithium nickelate, lithium manganese oxide, lithium manganate, lithium nickel manganate, lithium-rich manganese-based, lithium manganese iron phosphate, lithium nickel cobalt aluminum oxide, lithium nickel cobalt manganate, lithium iron phosphate, lithium vanadium phosphate; the conductive agent is one or more of vapor grown carbon fiber, carbon nanotube, multi-walled carbon nanotube; the negative electrode material layer is obtained by drying a negative electrode slurry, the negative electrode slurry comprising a negative electrode active material, a sulfide electrolyte, a binder and a conductive agent; the solid content of the negative electrode slurry is 45-60%; the weight ratio of the negative electrode active material, the sulfide electrolyte, the binder and the conductive agent in the negative electrode slurry layer is (70-90):(7-25):(2-4):(1-2); the negative electrode active material is at least one of micron silicon, nano silicon, silicon monoxide, homogeneous silicon carbon; the binder comprises at least one of fluorine glue, styrene butadiene styrene triblock copolymer, hydrogenated styrene butadiene styrene triblock copolymer, hydrogenated butyl nitrile rubber, butyl nitrile rubber, SEBS, polymethyl methacrylate, polyethylene oxide; the sulfide electrolyte is one or more of LGPS, LPS, Li6PS5X, LiSiPSX; wherein, in the Li6PS5X, LiSiPSX, X is selected from at least one of F, Cl, Br, I.

4. The solid-state soft-pack battery of claim 1, wherein, The pore diameter of the porous insulating polymer substrate is 1-1000um; the porous insulating polymer substrate is at least one of PET, PVDF, PTFE material.

5. The solid-state soft-pack battery of claim 1, wherein The electrolyte layer comprises a binder and a sulfide electrolyte; the binder comprises at least one of fluorine glue, styrene butadiene styrene triblock copolymer, hydrogenated styrene butadiene styrene triblock copolymer, hydrogenated butyl nitrile rubber, butyl nitrile rubber, SEBS, polymethyl methacrylate, polyethylene oxide; the sulfide electrolyte is one or more of LGPS, LPS, Li6PS5X, LiSiPSX; wherein, in the Li6PS5X, LiSiPSX, X is selected from at least one of F, Cl, Br, I.

6. The solid-state soft-pack battery according to any one of claims 1 to 5, wherein The surface capacity of the positive electrode material layer located in the middle of the solid-state soft pack battery is 3-5 mAh / cm 2 The surface capacity of the positive electrode material layer located at the outermost side of the solid-state soft pack battery is 1.5-2.5 mAh / cm 2 The surface capacity of the negative electrode material layer located in the middle of the solid-state soft pack battery is 3.3-5.5 mAh / cm 2 The surface capacity of the negative electrode material layer located at the outermost side of the solid-state soft pack battery is 1.65-2.75 mAh / cm 2 .

7. A method of manufacturing the solid-state soft-pack battery according to any one of claims 1 to 6, characterized by, The method comprises the following steps: (1) cutting the rate type solid state battery electrode sheet and the polymer-based sulfide electrolyte layer respectively; (2) stacking the three-layer rate type solid state battery electrode sheet and the two-layer polymer-based sulfide electrolyte layer alternately, and arranging the two-layer polymer-based sulfide electrolyte layer between the intervals formed by stacking the three-layer rate type solid state battery electrode sheet to obtain a rate type solid state soft pack battery.

8. The production method according to claim 7, wherein The preparation method of the rate type solid state battery electrode sheet is: The positive electrode material layer is formed by coating a positive electrode slurry on the side of the porous composite current collector away from the negative electrode current collector, and the negative electrode material layer is formed by coating a negative electrode slurry on the side of the negative electrode current collector away from the positive electrode current collector, and then drying to obtain a rate type solid-state battery electrode sheet; the porous composite current collector is prepared by punching the positive electrode current collector and the negative electrode current collector and then arranging them on the two sides of a polymer-based sulfide electrolyte layer.

9. The production method according to claim 7, wherein The polymer-based sulfide electrolyte layer is prepared by: dissolving a binder in an organic solvent to obtain a glue solution; adding a sulfide electrolyte into the glue solution and mixing to obtain an electrolyte slurry; and coating the electrolyte slurry on a porous insulating polymer substrate to obtain a polymer-based sulfide electrolyte layer.

10. The production method according to claim 8, wherein The positive electrode slurry is prepared by: dissolving a binder in a solvent to obtain a glue solution, and adding a positive electrode active material, a conductive agent and a sulfide electrolyte into the glue solution and mixing to obtain a positive electrode slurry; and the negative electrode slurry is prepared by: adding a negative electrode active material, a conductive agent and a sulfide electrolyte into the glue solution and mixing to obtain a negative electrode slurry.

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