Electrolyte membrane, method for producing the same, solid-state battery, and electric device

Abstract

The present application relates to a kind of electrolyte membrane and its preparation method, solid-state battery and electric equipment, the electrolyte membrane includes solid-state electrolyte layer, the solid-state electrolyte layer includes fiber and solid-state electrolyte particle, the diameter of the fiber is D1, the length of the fiber is L1, the particle size of the solid-state electrolyte particle is D2, and D1 50 The present application can effectively reduce the impedance while inhibiting the generation of cracks by introducing fibers matching the size of solid-state electrolyte particles, thereby synergistically improving the safety and electrochemical performance of solid-state batteries.

Description

Technical Field

[0001] This invention relates to the field of battery technology, and in particular to electrolyte membranes and their preparation methods, solid-state batteries, and electrical devices. Background Technology

[0002] Solid-state batteries achieve electronic insulation and ion transport between adjacent electrodes through a solid electrolyte. However, the solid electrolyte layer containing the solid electrolyte is susceptible to deformation, cracking, or even breakage due to external forces, which affects ion transport and thus the electrochemical performance of the solid-state battery, and also poses a short-circuit risk. Summary of the Invention

[0003] Therefore, it is necessary to address the above problems by providing an electrolyte membrane and its preparation method, a solid-state battery, and an electrical device. By introducing fibers that match the particle size of the solid electrolyte, the influence of fibers on impedance can be effectively reduced while suppressing crack formation, thereby improving the safety and electrochemical performance of the solid-state battery.

[0004] A first aspect of the present invention provides an electrolyte membrane comprising a solid electrolyte layer, the solid electrolyte layer comprising fibers and solid electrolyte particles, wherein the diameter of the fibers is D1, the length of the fibers is L1, and the particle size of the solid electrolyte particles is D2, and D1 < D2 < L1; wherein D2 is the median particle size D of the solid electrolyte particles. 50 .

[0005] In one embodiment, 100nm ≤ D1 ≤ 14μm; and / or, 200nm ≤ D2 ≤ 20μm; and / or, 50μm ≤ L1 ≤ 300μm.

[0006] In one embodiment, the fiber is selected from insulating fibers; and / or, the solid electrolyte particles comprise at least one sulfide solid electrolyte particle.

[0007] In one embodiment, the solid electrolyte layer further comprises a binder.

[0008] In one embodiment, in the solid electrolyte layer comprising solid electrolyte particles, binder and fibers, the mass fraction of the solid electrolyte particles is Q1, 75wt%≤Q1≤98wt%, the mass fraction of the fibers is Q2, 0wt%<Q2≤5wt%, and the mass fraction of the binder is Q3, 2wt%≤Q3≤20wt%.

[0009] In one embodiment, the electrolyte membrane further includes an insulating base film layer having a thickness direction, the base film layer having a first surface and a second surface opposite to each other along the thickness direction, wherein at least one surface is provided with the solid electrolyte layer; the base film layer is provided with a through hole that penetrates the base film layer along the thickness direction.

[0010] In one embodiment, the diameter of the through hole is D3; D2 < D3, and / or, D3 < L1, and / or, 30 μm ≤ D3 ≤ 200 μm.

[0011] In one embodiment, the porosity of the base film layer is P, where 20% ≤ P ≤ 50%.

[0012] In one embodiment, the base film layer is made of polyethylene, polypropylene, or aramid.

[0013] In one embodiment, the solid electrolyte layer includes a first solid electrolyte layer and a second solid electrolyte layer, wherein the first solid electrolyte layer is disposed on a first surface and the second solid electrolyte layer is disposed on a second surface.

[0014] In one embodiment, the fiber comprises a first fiber and a second fiber, the first solid electrolyte layer comprises the first fiber, the second solid electrolyte layer comprises the second fiber, and the diameter of the first fiber is D. 11 The diameter of the second fiber is D 12 And D 12 ≤D 11 ; and / or, the thickness of the second solid electrolyte layer is less than or equal to the thickness of the first solid electrolyte layer.

[0015] In one embodiment, 5μm≤D 11 ≤14μm; and / or, 100nm≤D 12 ≤10μm.

[0016] A second aspect of the present invention provides a method for preparing the electrolyte membrane described above, comprising the following steps:

[0017] The fiber and the solid electrolyte particles are mixed in a solvent to prepare a solid electrolyte slurry.

[0018] The solid electrolyte slurry is coated onto the surface of the carrier and dried to obtain the electrolyte membrane.

[0019] In one embodiment, the solvent also contains a binder; the fiber, the binder, and the solid electrolyte particles are mixed in the solvent to obtain a solid electrolyte slurry.

[0020] In one embodiment, the carrier is selected from a temporary carrier, and the preparation method further includes the step of removing the temporary carrier;

[0021] Alternatively, the carrier may be selected from the base film layer.

[0022] In one embodiment, the carrier is selected from a base film layer, the base film layer having a thickness direction, and the solid electrolyte slurry is coated on two opposing surfaces of the base film layer along the thickness direction; the two opposing surfaces of the base film layer along the thickness direction are a first surface and a second surface, the solid electrolyte slurry coated on the first surface is a first slurry, and the solid electrolyte slurry coated on the second surface is a second slurry; the fiber comprises a first fiber and a second fiber, and the specific steps of the preparation method are as follows:

[0023] First, the first fiber and the solid electrolyte particles are mixed in a solvent to prepare a first slurry. The first slurry is then coated onto the first surface and dried.

[0024] The second fiber and the solid electrolyte particles are then mixed in a solvent to prepare a second slurry. The second slurry is then coated onto the second surface and dried to obtain the electrolyte membrane.

[0025] In one embodiment, the diameter of the first fiber is D. 11 The length is L1, and the diameter of the second fiber is D. 12 And the length is L1, D 12 ≤D 11 <D2<L1;

[0026] And / or, the first slurry is dried to form a first solid electrolyte layer, and the second slurry is dried to form a second solid electrolyte layer, wherein the thickness of the second solid electrolyte layer is less than or equal to the thickness of the first solid electrolyte layer.

[0027] In one embodiment, the solid content of the first slurry is M1, 30% ≤ M1 ≤ 60%; and / or, the solid content of the second slurry is M2, 30% ≤ M2 ≤ 60%.

[0028] A third aspect of the present invention provides a solid-state battery, comprising an electrode and an electrolyte membrane, or comprising an electrode and an electrolyte membrane prepared by the preparation method described above; wherein the electrode and the electrolyte membrane are stacked alternately.

[0029] A fourth aspect of the present invention provides an electrical device comprising the aforementioned solid-state battery, or comprising a battery module, wherein the battery module comprises the aforementioned solid-state battery.

[0030] This invention utilizes elongated fibers with a diameter D1 smaller than a length L1 mixed with solid electrolyte particles of a particle size D2, and controls the dimensional relationship between D1, D2, and L1 to form a three-dimensional reinforcing network woven from fibers within the solid electrolyte layer. This three-dimensional reinforcing network effectively improves the toughness of the solid electrolyte layer, restricts the displacement of solid electrolyte particles, enhances the structural stability and crack resistance of the solid electrolyte layer, enabling it to withstand greater pressure in subsequent pressing processes (such as hydraulic, hot pressing, and / or rolling) without easily deforming or cracking, ensuring ion transport performance, significantly reducing the risk of short circuits caused by crack propagation, and improving the safety and electrochemical performance of solid-state batteries.

[0031] Furthermore, controlling the fiber diameter D1 to be smaller than the solid electrolyte particle diameter D2 helps reduce the fiber's obstruction of the contact interface between solid electrolyte particles, promoting direct contact between the particles and effectively reducing the interfacial ohmic impedance for ion transport. Simultaneously, the uniform support of the three-dimensional reinforcement network enhances the structural uniformity and stability of the solid electrolyte layer, resulting in more uniform current distribution and ion flux at the electrode interface. This reduces polarization, lowers the internal resistance and polarization losses of the solid-state battery, and improves its electrochemical performance (such as rate performance) and extends its cycle life. Attached Figure Description

[0032] To more clearly illustrate the technical solutions in the embodiments of this application or the conventional technology, the drawings used in the description of the embodiments or the conventional technology will be briefly introduced below. Obviously, the drawings described below are only some embodiments of this application. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort.

[0033] Figure 1 This is a schematic diagram of the structure of an electrolyte membrane according to an embodiment of the present invention;

[0034] Figure 2 This is a schematic diagram of the structure of an electrolyte membrane according to another embodiment of the present invention;

[0035] Figure 3 The graph shows the relationship between the number of cycles and the specific capacity of the solid-state batteries in Embodiment 1 and Comparative Example 1 of the present invention.

[0036] Figure 4 This is a graph showing the relationship between the number of cycles and capacity retention of the solid-state batteries in Embodiment 1 and Comparative Example 1 of the present invention.

[0037] In the figure: 10, solid electrolyte layer; 101, solid electrolyte particles; 102, fiber; 11, first solid electrolyte layer; 12, second solid electrolyte layer; 20, base film layer; 201, through-hole. Detailed Implementation

[0038] To facilitate understanding of the present invention, it will be described in more detail below. However, it should be understood that the present invention can be implemented in many different forms and is not limited to the embodiments or examples described herein. Rather, these embodiments or examples are provided to make the disclosure of the present invention more thorough and complete.

[0039] Unless otherwise defined, all technical and scientific terms used herein have the same meaning as commonly understood by one of ordinary skill in the art to which this invention pertains. The terminology used herein in the specification of this invention is for the purpose of describing particular embodiments or examples only and is not intended to limit the invention. The optional scope of the term "and / or" as used herein includes any one of two or more of the related listed items, as well as any and all combinations of the related listed items, including any two related listed items, any more related listed items, or a combination of all related listed items.

[0040] In this invention, numerical ranges are involved. Unless otherwise specified, the numerical ranges are considered continuous and include the minimum and maximum values ​​of the range, as well as every value between the minimum and maximum values. Furthermore, when the range refers to integers, it includes every integer between the minimum and maximum values ​​of the range. Additionally, when multiple ranges are provided to describe features or characteristics, the ranges may be merged. In other words, unless otherwise specified, all ranges disclosed herein should be understood to include any and all subranges to which they are included.

[0041] Because the solid electrolyte layer in existing technologies has low toughness, it is highly susceptible to microcracks when subjected to external forces during subsequent pressing processes (such as hot pressing and / or rolling). The formation of cracks directly disrupts the continuous lithium-ion transport path, leading to a sharp increase in interfacial impedance and rapid capacity decay. More seriously, cracks may propagate and penetrate the solid electrolyte layer, posing a serious safety hazard of short circuits between the positive and negative electrodes in solid-state batteries.

[0042] like Figure 1 As shown, the electrolyte membrane provided by the present invention includes a solid electrolyte layer 10, which comprises solid electrolyte particles 101 and fibers 102. The diameter of the fibers 102 is D1, the length of the fibers 102 is L1, and the particle size of the solid electrolyte particles 101 is D2, where D1 < D2 < L1; wherein, D2 is the median particle size D of the solid electrolyte particles. 50 D1 can be the average diameter of the fiber, and L1 can be the average length of the fiber.

[0043] In this embodiment, the average diameter and average length of the fiber can be determined by the following method:

[0044] Ethanol was used as the solvent to disperse the fiber samples (non-conductive fibers), and gold sputtering was applied to improve image quality. Multiple regions and magnifications were selected for image acquisition (specifically using a scanning electron microscope). Low magnification (micrometer level) was mainly used for length measurement, while high magnification (nanometer level) was mainly used for diameter measurement. After calibrating the scale with a standard sample, data was extracted manually or automatically using software (such as ImageJ software or a custom Python script). For diameter measurement, the diameter was measured perpendicular to the fiber, with each fiber measured three times at different locations, and the average value was taken. At least 100 fibers were measured to obtain the average diameter. For length measurement, lines were drawn along the fiber curvature path, and the length was measured. At least 100 fibers were measured to obtain the average length. If an automatic length extraction method was used, the specific steps were: select the number of fibers (e.g., 100), draw the lines, and the software automatically output the average value.

[0045] Therefore, by using elongated fibers 102 with a diameter D1 smaller than a length L1, mixed with solid electrolyte particles 101 with a particle size D2, and controlling the dimensional relationship between D1, D2, and L1, a three-dimensional reinforcing network composed of interwoven fibers 102 can be formed within the solid electrolyte layer 10. This three-dimensional reinforcing network can effectively improve the toughness of the solid electrolyte layer 10, restrict the displacement of the solid electrolyte particles 101, enhance the structural stability and crack resistance of the solid electrolyte layer 10, enabling it to withstand greater pressure in subsequent pressing processes (such as hydraulic, hot pressing, and / or rolling) without easily deforming or cracking, ensuring ion transport performance, significantly reducing the risk of short circuits caused by crack propagation, and improving the safety and electrochemical performance of the solid-state battery.

[0046] Furthermore, controlling the diameter D1 of the fiber 102 to be smaller than the particle size D2 of the solid electrolyte particles 101 helps reduce the obstruction of the fiber 102 at the contact interface between the solid electrolyte particles 101, promoting direct contact between the solid electrolyte particles 101, thereby effectively reducing the interfacial ohmic impedance of ion transport. Simultaneously, the uniform support of the three-dimensional reinforcement network enhances the structural uniformity and stability of the solid electrolyte layer 10, resulting in a more uniform current distribution and ion flux at the electrode interface, weakening polarization, reducing the internal resistance and polarization loss of the solid battery, which is beneficial for improving the electrochemical performance of the solid battery (such as rate performance) and extending its cycle life.

[0047] It is worth noting that the three-dimensional reinforcing network formed by the interwoven fibers 102 can also enable the solid electrolyte layer 10 to maintain excellent mechanical strength even with a reduced thickness, thereby enabling the thinner fabrication of the solid electrolyte layer 10, further shortening the ion transport path, reducing the overall impedance, and improving the electrochemical performance of the solid battery.

[0048] In some embodiments, the particle size D2 of the solid electrolyte particles 101 is controlled between 200 nm and 20 μm, for example, D2 is controlled to be 200 nm, 500 nm, 800 nm, 1 μm, 2 μm, 3 μm, 4 μm, 5 μm, 6 μm, 7 μm, 8 μm, 9 μm, 10 μm, 11 μm, 12 μm, 13 μm, 14 μm, 15 μm, 16 μm, 17 μm, 18 μm, 19 μm or 20 μm, etc.

[0049] In some embodiments, the diameter D1 of the fiber 102 is controlled between 100 nm and 14 μm, for example, D1 is controlled to be 100 nm, 200 nm, 300 nm, 400 nm, 500 nm, 600 nm, 700 nm, 800 nm, 900 nm, 1 μm, 2 μm, 3 μm, 4 μm, 5 μm, 6 μm, 7 μm, 8 μm, 9 μm, 10 μm, 11 μm, 12 μm, 13 μm, 14 μm, etc.

[0050] In some embodiments, the length L1 of the fiber 102 is controlled between 50 μm and 300 μm, for example, L1 is controlled to be 50 μm, 60 μm, 70 μm, 80 μm, 90 μm, 100 μm, 150 μm, 200 μm, 250 μm, 300 μm, etc.

[0051] Thus, by controlling the size range of D1 and D2, the fiber 102 can have a certain toughness while maintaining good contact between solid electrolyte particles 101. At the same time, by further controlling the size range of D2 and L1, it is ensured that the fiber 102 can fully overlap between solid electrolyte particles 101 to construct a continuous three-dimensional reinforcing network. This network not only helps to uniformly disperse the external pressure on the solid electrolyte layer 10, alleviate stress concentration, and inhibit crack initiation and propagation, but also provides macroscopic toughness support for the entire solid electrolyte layer 10.

[0052] In addition, by controlling the particle size D2 of the solid electrolyte particles 101, the size matching with the fiber 102 is ensured to promote interfacial bonding and stress transfer, and the particles are able to achieve tight and uniform stacking under the support of the three-dimensional reinforcement network, thus ensuring the efficiency and stability of the ion transport path.

[0053] In some embodiments, the fiber 102 is selected from insulating fibers, such as any one of aramid fibers, polyimide fibers, polyphenylene sulfide fibers, polyarylate fibers, etc., thereby ensuring that the fiber 102, while playing a mechanical reinforcing role, will not introduce an electronic conductive path between the positive and negative electrodes, eliminating the risk of internal micro-short circuits and self-discharge caused by the conductivity of the fiber 102, and improving the safety and cycle stability of the solid-state battery.

[0054] In some embodiments, the solid electrolyte particles 101 include at least one sulfide solid electrolyte particle, so as to utilize the inherently high room-temperature ionic conductivity of the sulfide solid electrolyte to reduce the internal resistance and polarization of the solid-state battery and improve the rate performance.

[0055] Among them, the sulfide solid electrolyte particles contain Li k M 2 l S m X 2 n , where M 2 is selected from at least one of Sn, Mg, Ba, B, Al, Ga, I, Si, Ge, Pb, N, P, As, Sb, Bi, Ti, Cr, Mn, Fe, Co, Ni, Cu, Zr, Nb, Mo, Tc, Ru, Rh, Pd, Ag, Ta, and La, and X 2 is selected from at least one of F, Cl, Br, I, Se, Te, and O, 0 < k ≤ 12, 0 < l ≤ 6, 0 < m ≤ 12, and 0 ≤ n ≤ 6.

[0056] In some embodiments, the sulfide solid electrolyte particles contain Li7P3S 11 、Li 10 GeP2S 12 , at least one of Li6PS5Cl.

[0057] In some embodiments, the solid electrolyte layer 10 further includes a binder. The core role of the binder in the slurry preparation is to prevent the solid electrolyte particles 101 and the fibers 102 in the slurry from agglomerating due to van der Waals forces, ensure the uniform distribution of components, endow the slurry with appropriate viscosity through the entanglement or interaction of polymer chains, ensure that the slurry can be stably coated, and avoid sedimentation or delamination. After the solvent evaporates, the binder cures between the solid electrolyte particles 101 and the fibers 102 to form a "bonding bridge", and then form a complete and flexible solid electrolyte layer 10 to prevent cracking and powder falling. A suitable binder does not hinder the ion transport between particles and assists the electron movement in the conductive network, which is beneficial to reducing the internal resistance of the battery and improving the rate performance of the battery.

[0058] Among them, the binder is selected from at least one of ethylene-vinyl acetate copolymer, styrene-butadiene rubber, nitrile rubber, polyethylene oxide, polymethyl methacrylate, polyacrylic acid, and polyethylene glycol.

[0059] In the solid electrolyte layer 10 comprising solid electrolyte particles 101, binder, and fibers 102, the mass fraction of the solid electrolyte particles 101 is Q1, 75wt%≤Q1≤98wt%; the mass fraction of the fibers 102 is Q2, 0wt%<Q2≤5wt%; and the mass fraction of the binder is Q3, 2wt%≤Q3≤20wt%. This ensures that the fibers 102 effectively construct a three-dimensional reinforcing network to improve toughness, while avoiding excessive occupation of ion transport channels or obstruction of direct contact between solid electrolyte particles 101 due to excessive fiber 102 content, thereby improving the ion conductivity of the solid electrolyte layer 10.

[0060] In some embodiments, the electrolyte membrane of the present invention further includes an insulating base film layer 20 for supporting the solid electrolyte layer 10, which facilitates the continuous industrial production of the electrolyte membrane and improves the mechanical strength and structural stability of the electrolyte membrane. At the same time, the insulating base film layer 20 also helps to reduce the risk of short circuit.

[0061] The base film layer 20 has a thickness direction and has a first surface and a second surface opposite to each other along the thickness direction. At least one surface is provided with the solid electrolyte layer 10. The base film layer 20 is provided with a through hole 201, which penetrates the base film layer 20 along the thickness direction, thereby ensuring the effective transport of ions.

[0062] In some embodiments, the diameter of the through hole 201 is D3, and D2 < D3 is controlled so that the solid electrolyte particles 101 can fill the interior of the through hole 201, so that ions can be transported through the solid electrolyte particles 101 in the through hole 201 and pass through the base film layer 20.

[0063] In some embodiments, D3 is controlled to be less than L1, allowing fibers 102 with a length L1 greater than the diameter D3 of the through-hole 201 to interweave at the through-hole 201, forming a locally reinforcing network at the through-hole 201 that is less prone to collapse. This enhances the local structural strength of the through-hole 201 region and helps ensure the toughness of the electrolyte membrane. Based on this, the present invention can appropriately increase the pore size of the through-hole 201 while maintaining a length L1 less than that of the fibers 102, which facilitates the filling of solid electrolyte particles 101, increases the ion conduction area, and improves transport efficiency.

[0064] In some implementations, the diameter is controlled to be 30 μm ≤ D3 ≤ 200 μm, for example, D3 is controlled to be 30 μm, 40 μm, 50 μm, 60 μm, 70 μm, 80 μm, 90 μm, 100 μm, 110 μm, 120 μm, 130 μm, 140 μm, 150 μm, 160 μm, 170 μm, 180 μm, 190 μm, or 200 μm. Thus, under the constraints of the above dimensional relationships, this range can increase the ion conduction area while maintaining sufficient mechanical support, achieving an optimal balance between mechanical strength and ion transport efficiency.

[0065] In some embodiments, the porosity P of the base film layer 20 is 20% ≤ P ≤ 50%, for example, P is 20%, 25%, 30%, 35%, 40%, 45%, or 50%, etc., so that the base film layer 20 can effectively support the solid electrolyte layer 10 while having sufficient ion channels to maintain low interfacial impedance. In addition, it is also beneficial to enhance the contact stability between the solid electrolyte layer 10 and the base film layer 20, and improve the interfacial stability of the electrolyte membrane.

[0066] In some embodiments, the base film layer 20 is made of materials such as polyethylene, polypropylene, or aramid.

[0067] Combination Figure 1 and Figure 2 As shown, the solid electrolyte layer 10 of the present invention includes a first solid electrolyte layer 11 and a second solid electrolyte layer 12. The first solid electrolyte layer 11 is disposed on a first surface, and the second solid electrolyte layer 12 is disposed on a second surface. This avoids direct contact between the base film layer 20 and the electrode, thereby effectively reducing the interfacial impedance between the electrode and the electrolyte film, and thus reducing the impedance of the solid-state battery.

[0068] The fiber 102 comprises a first fiber and a second fiber, the first solid electrolyte layer 11 comprises the first fiber, the second solid electrolyte layer 12 comprises the second fiber, and the diameter of the first fiber is D. 11 The diameter of the second fiber is D 12 And D 12 ≤D 11 .

[0069] Therefore, when preparing the solid electrolyte layer 10 on the base film layer 20, a slurry containing the first fiber is first coated. Taking advantage of its good mechanical stability and film-forming properties, a first solid electrolyte layer 11 with good supporting strength is formed on the first surface of the base film layer 20. This allows the second solid electrolyte layer 12 on the opposite second surface to maintain interfacial bonding and electrochemical function. In this second solid electrolyte layer 12, the diameter of the second fiber can be smaller than the diameter of the first fiber, thereby further reducing the physical barrier to the contact between the solid electrolyte particles 101. This is beneficial for building a more continuous and compact ion transport network inside the layer to reduce impedance and balance the requirements of structural strength and electrochemical performance.

[0070] In some embodiments, the thickness of the second solid electrolyte layer 12 is less than or equal to the thickness of the first solid electrolyte layer 11. When the first solid electrolyte layer 11 has good toughness due to the use of the first fiber, the thickness of the second solid electrolyte layer 12 can be equal to or even less than the thickness of the first solid electrolyte layer 11. In particular, when the thickness of the second solid electrolyte layer 12 is less than the thickness of the first solid electrolyte layer 11, it is beneficial to reduce the overall thickness of the electrolyte membrane and shorten the ion migration path.

[0071] In some embodiments, the diameter D of the first fiber is... 11 Controlled between 5μm and 14μm, for example, controlling D 11 The diameters are 5μm, 6μm, 7μm, 8μm, 9μm, 10μm, 11μm, 12μm, 13μm, 14μm, etc.; the diameter D of the second fiber is... 12 Controlled between 100nm and 10μm, for example, controlling D 12 The nm values ​​are 100nm, 200nm, 300nm, 400nm, 500nm, 600nm, 700nm, 800nm, 900nm, 1μm, 2μm, 3μm, 4μm, 5μm, 6μm, 7μm, 8μm, 9μm, 10μm, etc. Therefore, D 11 The range allows the first solid electrolyte layer 11 to have good toughness without excessively hindering the contact between solid electrolyte particles 101, thereby making the second solid electrolyte layer 12 thinner, reducing the overall thickness of the electrolyte membrane and improving the electrochemical performance of the finished solid-state battery.

[0072] The present invention also provides a method for preparing the electrolyte membrane, comprising the following steps:

[0073] The fiber 102 and the solid electrolyte particles 101 are mixed in a solvent to prepare a solid electrolyte slurry.

[0074] The solid electrolyte slurry is coated onto the surface of the carrier and dried to obtain the electrolyte membrane.

[0075] In some embodiments, the solvent is selected from xylene, acetonitrile, or dimethyltetrahydrofuran, and a binder is also mixed in the solvent. In this case, the fiber, the binder, and the solid electrolyte particles 101 are mixed in the solvent to prepare a solid electrolyte slurry, so that the prepared solid electrolyte layer 10 also contains a binder.

[0076] In some embodiments, the carrier is selected from temporary carriers, such as films made of materials like polyethylene terephthalate (PET), polyethylene (PE), polypropylene (PP), or polyvinyl chloride (PVC). In this case, the preparation method further includes the step of removing the temporary carrier, and the obtained electrolyte membrane consists only of the solid electrolyte layer 10.

[0077] In some embodiments, the carrier is selected from the base film layer 20, in which case the electrolyte membrane includes the base film layer 20 and the solid electrolyte layer 10.

[0078] When the carrier is selected from the base film layer 20, the base film layer 20 has a thickness direction, and the solid electrolyte slurry is coated on two opposite surfaces of the base film layer 20 along the thickness direction. The solid electrolyte slurry coated on the first surface is the first slurry, and the solid electrolyte slurry coated on the second surface is the second slurry.

[0079] When the fiber comprises a first fiber and a second fiber, the first fiber and the solid electrolyte particles 101 are first mixed in a solvent to obtain a first slurry, the first slurry is coated on a first surface and dried; then the second fiber and the solid electrolyte particles 101 are mixed in a solvent to obtain a second slurry, the second slurry is coated on a second surface and dried to obtain the electrolyte membrane.

[0080] Wherein, the diameter of the first fiber is D 11 The length is L1, and the diameter of the second fiber is D. 12 And the length is L1, D 12 ≤D 11 <D2<L1.

[0081] In some embodiments, the first slurry is dried to form a first solid electrolyte layer 11, and the second slurry is dried to form a second solid electrolyte layer 12, wherein the thickness of the second solid electrolyte layer 12 is less than or equal to the thickness of the first solid electrolyte layer 11.

[0082] In some embodiments, the solid content of the first slurry is M1, 30%≤M1≤60%, for example, M1 is controlled to be 30%, 35%, 40%, 45%, 50%, 55% or 60%; the solid content of the second slurry is M2, 30%≤M2≤60%, for example, M2 is controlled to be 30%, 35%, 40%, 45%, 50%, 55% or 60%.

[0083] Figure 1 and Figure 2 Some embodiments of the present invention are illustrated and are not drawn to scale for clarity.

[0084] The present invention also provides a solid-state battery, comprising an electrode and the electrolyte membrane, or comprising an electrode and an electrolyte membrane prepared by the preparation method described above; wherein the electrode and the electrolyte membrane are stacked alternately.

[0085] The present invention also provides an electrical device, including the solid-state battery, or including a battery module, wherein the battery module includes the solid-state battery.

[0086] This invention provides an electrical device that includes the aforementioned solid-state battery and uses the aforementioned solid-state battery as a power source. Specific examples of this electrical device include, but are not limited to: power tools driven by an electric motor; electric vehicles, including pure electric vehicles (EVs), hybrid electric vehicles (HEVs), plug-in hybrid electric vehicles (PHEVs), etc.; electric two-wheeled vehicles, including electric bicycles (E-bikes) and electric scooters (E-scooters); electric golf carts; and energy storage systems.

[0087] The technical solution of the present invention will be further described below through specific embodiments. However, those skilled in the art will understand that the following embodiments are only for illustrating the present invention and should not be regarded as limiting the scope of the present invention. Unless otherwise specified, specific conditions in the embodiments are performed under conventional conditions or conditions recommended by the manufacturer. Reagents or instruments used without specified manufacturers are all commercially available conventional products.

[0088] Example 1

[0089] 9.2g of solid electrolyte Li6PS5Cl (median particle size D) was added. 50 =10μm), 0.5g binder, 0.3g aramid fiber (average length 150μm, average diameter 6μm) and 15.0g solvent were mixed and stirred to obtain the first slurry.

[0090] 9.2g of solid electrolyte Li6PS5Cl (median particle size D) was added. 50=10μm), 0.5g binder, 0.3g aramid fiber (average length 150μm, average diameter 6μm) and 15.0g solvent are mixed and stirred to obtain the second slurry.

[0091] First, place the polyethylene polymer base film in a punching device for punching. Set the punching diameter D3 to 110μm-130μm and the porosity to 35% to obtain the base film layer. A commercially available needle roller punching machine can be used.

[0092] The first slurry was then coated onto the first surface of the base film (one of the two surfaces of the base film opposite each other along the thickness direction), with a doctor blade thickness (the distance between the doctor blade and the base film) of 70 μm and a target coating thickness of 60 μm. After coating, the film was pre-dried in a vacuum drying oven at 60°C for 4 hours, resulting in a final first solid electrolyte layer thickness of 61 μm. The second slurry was then coated onto the second surface of the base film (the other of the two surfaces of the base film opposite each other along the thickness direction), with a doctor blade thickness of 70 μm and a target coating thickness of 60 μm. The film was then pre-dried in a vacuum drying oven at 60°C for 12 hours to obtain a dry film, resulting in a final second solid electrolyte layer thickness of 63 μm.

[0093] The dried film is compacted and an electrolyte membrane of the required size is obtained from it. The electrolyte membrane includes a first solid electrolyte layer, a base film layer and a second solid electrolyte layer stacked sequentially along the thickness direction.

[0094] Example 2

[0095] 8.5g of solid electrolyte Li6PS5Cl (median particle size D) was added. 50 =20μm), 1.4g binder, 0.1g polyimide fiber (average length 300μm, average diameter 14μm) and 15.0g solvent were mixed and stirred to obtain the first slurry.

[0096] 8.5g of solid electrolyte Li6PS5Cl (median particle size D) was added. 50 =20μm), 1.4g binder, 0.1g polyimide fiber (average length 300μm, average diameter 150nm) and 15.0g solvent were mixed and stirred to obtain the second slurry.

[0097] First, the aramid base film is placed in a drilling device for drilling. The drilling diameter D3 is set to 180μm-200μm and the porosity is 41%, thus obtaining the base film layer.

[0098] The first slurry was then coated onto the first surface of the base film (one of the two surfaces of the base film opposite each other along the thickness direction), with a doctor blade thickness of 90 μm and a target coating thickness of 80 μm. After coating, it was placed in a vacuum drying oven at 60°C for 4 hours to pre-dry, resulting in a final first solid electrolyte layer thickness of 75 μm. The second slurry was then coated onto the second surface of the base film (the other of the two surfaces of the base film opposite each other along the thickness direction), with a doctor blade thickness of 55 μm and a target coating thickness of 45 μm. It was then placed in a vacuum drying oven at 60°C for 12 hours to pre-dry, resulting in a dry film and a final second solid electrolyte layer thickness of 40 μm.

[0099] Example 3

[0100] 8.7g of solid electrolyte Li6PS5Cl (median particle size D) was added. 50 =500nm), 0.8g binder, 0.5g polyarylate fiber (average length 60μm, average diameter 200nm) and 15.0g solvent were mixed and stirred to obtain the first slurry.

[0101] 8.7g of solid electrolyte Li6PS5Cl (median particle size D) was added. 50 =500nm), 0.8g binder, 0.5g polyarylate fiber (average length 60μm, average diameter 150nm) and 15.0g solvent were mixed and stirred to obtain the second slurry.

[0102] First, the polypropylene base film is placed in a punching device for punching. The punching diameter D3 is set to 30μm-40μm and the porosity is 32%, thus obtaining the base film layer.

[0103] The first slurry was then coated onto the first surface of the base film (one of the two surfaces of the base film opposite each other along the thickness direction), with a doctor blade thickness of 60 μm and a target coating thickness of 50 μm. After coating, it was placed in a vacuum drying oven at 60°C for 4 hours to pre-dry, resulting in a final first solid electrolyte layer thickness of 45 μm. The second slurry was then coated onto the second surface of the base film (the other of the two surfaces of the base film opposite each other along the thickness direction), with a doctor blade thickness of 55 μm and a target coating thickness of 45 μm. It was then placed in a vacuum drying oven at 60°C for 12 hours to pre-dry, resulting in a dry film and a final second solid electrolyte layer thickness of 40 μm.

[0104] Example 4

[0105] 9.7g of solid electrolyte Li6PS5Cl (median particle size D) 50 =10μm), 0.2g binder, 0.1g polyphenylene sulfide fiber (average length 150μm, average diameter 150nm) and 15.0g solvent were mixed and stirred to obtain the first slurry.

[0106] 9.7g of solid electrolyte Li6PS5Cl (median particle size D) 50 =10μm), 0.2g binder, 0.1g polyphenylene sulfide fiber (average length 150μm, average diameter 150nm) and 15.0g solvent were mixed and stirred to obtain the second slurry.

[0107] First, place the polyethylene polymer base film in a drilling device for drilling. Set the drilling diameter D3 to 110μm-130μm and the porosity to 20% to obtain the base film layer.

[0108] The first slurry was then coated onto the first surface of the base film (one of the two surfaces of the base film opposite each other along the thickness direction), with a doctor blade thickness of 70 μm and a target coating thickness of 60 μm. After coating, it was placed in a vacuum drying oven at 60°C for 4 hours to pre-dry, resulting in a final first solid electrolyte layer thickness of 63 μm. The second slurry was then coated onto the second surface of the base film (the other of the two surfaces of the base film opposite each other along the thickness direction), with a doctor blade thickness of 70 μm and a target coating thickness of 60 μm. It was then placed in a vacuum drying oven at 60°C for 12 hours to pre-dry, resulting in a dry film and a final second solid electrolyte layer thickness of 62 μm.

[0109] Example 5

[0110] 7.5g of solid electrolyte Li6PS5Cl (median particle size D) was added. 50 The first slurry was obtained by mixing and stirring 2.0 g of binder, 0.5 g of aramid fiber (average length 150 μm, average diameter 14 μm) and 15.0 g of solvent.

[0111] 7.5g of solid electrolyte Li6PS5Cl (median particle size D) was added. 50 The second slurry was obtained by mixing and stirring 2.0 g of binder, 0.5 g of aramid fiber (average length 150 μm, average diameter 14 μm) and 15.0 g of solvent.

[0112] First, place the polyethylene polymer base film in a drilling device for drilling. Set the drilling diameter D3 to 110μm-130μm and the porosity to 50% to obtain the base film layer.

[0113] The first slurry was then coated onto the first surface of the base film (one of the two surfaces of the base film opposite each other along the thickness direction), with a doctor blade thickness of 80 μm and a target coating thickness of 70 μm. After coating, it was placed in a vacuum drying oven at 60°C for 4 hours to pre-dry, resulting in a final first solid electrolyte layer thickness of 65 μm. The second slurry was then coated onto the second surface of the base film (the other of the two surfaces of the base film opposite each other along the thickness direction), with a doctor blade thickness of 80 μm and a target coating thickness of 70 μm. It was then placed in a vacuum drying oven at 60°C for 12 hours to pre-dry, resulting in a dry film and a final second solid electrolyte layer thickness of 66 μm.

[0114] Comparative Example 1

[0115] 9.2g of solid electrolyte Li6PS5Cl (median particle size D) was added. 50 =10μm), 0.5g binder and 15.0g solvent were mixed and stirred to obtain the first slurry.

[0116] 9.2g of solid electrolyte Li6PS5Cl (median particle size D) was added. 50 =10μm), 0.5g binder and 15.0g solvent were mixed and stirred to obtain the second slurry.

[0117] First, place the polyethylene polymer base film in a drilling device for drilling. Set the drilling diameter D3 to 110μm-130μm and the porosity to 35% to obtain the base film layer.

[0118] The first slurry was then coated onto the first surface of the base film (one of the two surfaces of the base film opposite each other along the thickness direction), with a doctor blade thickness of 70 μm and a target coating thickness of 60 μm. After coating, it was placed in a vacuum drying oven at 60°C for 4 hours to pre-dry, resulting in a final first solid electrolyte layer thickness of 61 μm. The second slurry was then coated onto the second surface of the base film (the other of the two surfaces of the base film opposite each other along the thickness direction), with a doctor blade thickness of 70 μm and a target coating thickness of 60 μm. It was then placed in a vacuum drying oven at 60°C for 12 hours to pre-dry, resulting in a dry film and a final second solid electrolyte layer thickness of 63 μm.

[0119] The dried film is compacted and an electrolyte membrane of the required size is obtained from it. The electrolyte membrane includes a first solid electrolyte layer, a base film layer and a second solid electrolyte layer stacked sequentially along the thickness direction.

[0120] Cell fabrication method: The positive electrode, electrolyte membrane, and negative electrode are stacked together along the thickness direction of the base film to form a soft-pack battery cell. The electrolyte membrane has a length of 6.5 cm, a width of 5.5 cm, and a thickness of 127 μm; the positive electrode has a length of 5.6 cm, a width of 4.3 cm, and a thickness of 74 μm, and its positive active material layer includes ternary material NCM811, electrolyte Li6PS5Cl, conductive agent VGCF, and binder nitrile rubber; the negative electrode has a length of 5.8 cm, a width of 4.5 cm, and a thickness of 60 μm, and its negative active material layer includes silicon, electrolyte Li6PS5Cl, conductive agent VGCF, and binder nitrile rubber.

[0121] The electrolyte membranes prepared in Example 1 and Comparative Example 1 of this invention were assembled into pouch cells (i.e., solid-state batteries as described below) according to the above-described cell preparation method, and the cell performance was tested.

[0122] In the above embodiments and comparative examples, there will be a small difference between the target coating thickness of the first solid electrolyte layer and the corresponding final thickness of the first solid electrolyte layer, and there will also be a small difference between the target coating thickness of the second solid electrolyte layer and the corresponding final thickness of the second solid electrolyte layer.

[0123] The reason for the large difference between the doctor blade thickness and the corresponding target coating thickness is that the coated slurry will collapse due to factors such as solvent evaporation. Therefore, the doctor blade thickness is usually greater than the corresponding target coating thickness, and the difference is large.

[0124] The method for obtaining the thickness of the first solid electrolyte layer and the thickness of the second solid electrolyte layer is as follows: First, measure the thickness of the base film layer, then apply the first slurry, and after drying, measure the first total thickness of the base film layer and the first solid electrolyte layer. Subtract the thickness of the base film layer from the first total thickness to obtain the thickness of the first solid electrolyte layer. Then, apply the second slurry, and after drying, measure the second total thickness of the first solid electrolyte layer, the base film layer, and the second solid electrolyte layer. Subtract the thickness of the base film layer and the thickness of the first solid electrolyte layer from the second total thickness to obtain the thickness of the second solid electrolyte layer.

[0125] Figure 3 This is a graph showing the relationship between the number of cycles and the specific capacity of a set of solid-state batteries corresponding to Comparative Example 1 and Example 1. At a rate of 1C, the battery was charged at a constant current to 4.25V and discharged at a constant current to 2.5V. After 17 cycles, the specific capacity of Comparative Example 1 was 97.3mAh / g, and after 400 cycles, the specific capacity of Example 1 was 116.6mAh / g. The specific capacity of Example 1 after 400 cycles was still significantly higher than that of Comparative Example 1, which only had 17 cycles.

[0126] Figure 4This is a graph showing the relationship between the number of cycles and capacity retention rate for Comparative Example 1 and Example 1. A capacity retention rate below 80% is considered the end of the battery's effective lifespan. Figure 4 It can be seen that Comparative Example 1 retained 79.3% of its capacity after 17 cycles at a 1C rate, while Example 1 retained 79.4% of its capacity after 400 cycles at the same rate.

[0127] In summary, the battery using the electrolyte membrane of Example 1 exhibits significantly better cycle performance at high rates than the battery using the electrolyte membrane of Comparative Example 1. This is because the addition of fibers to the electrolyte membrane in Example 1 results in higher toughness and less deformation during the compaction process with the electrode. Furthermore, the combination with the electrode causes less strain on the current collector during hot pressing, maintaining the battery's shape and ensuring a tight, uniform, and stable interfacial contact between the electrolyte membrane and the electrode. Additionally, fewer microcracks are generated within the solid electrolyte layer, further enhancing the stability of the interfacial contact and ultimately leading to superior cycle performance.

[0128] The technical features of the above embodiments can be combined in any way. For the sake of brevity, not all possible combinations of the technical features in the above embodiments are described. However, as long as there is no contradiction in the combination of these technical features, they should be considered to be within the scope of this specification.

[0129] The embodiments described above are merely illustrative of several implementations of the present invention, and while the descriptions are relatively specific and detailed, they should not be construed as limiting the scope of the invention patent. It should be noted that those skilled in the art can make various modifications and improvements without departing from the concept of the present invention, and these all fall within the protection scope of the present invention. Therefore, the protection scope of this invention patent should be determined by the appended claims.

Claims

1. An electrolyte membrane, characterized in that, The electrolyte membrane includes a solid electrolyte layer comprising fibers and solid electrolyte particles. The fibers have a diameter of D1 and a length of L1. The solid electrolyte particles have a particle size of D2, where D1 < D2 < L1; and D2 is the median particle size of the solid electrolyte particles. 50 .

2. The electrolyte membrane according to claim 1, characterized in that, 100nm≤D1≤14μm; and / or, 200nm≤D2≤20μm; and / or, 50μm≤L1≤300μm.

3. The electrolyte membrane according to claim 1, characterized in that, The fiber is selected from insulating fibers; and / or, the solid electrolyte particles comprise at least one sulfide solid electrolyte particle.

4. The electrolyte membrane according to claim 1, characterized in that, The solid electrolyte layer also includes a binder.

5. The electrolyte membrane according to claim 4, characterized in that, In the solid electrolyte layer comprising solid electrolyte particles, binder and fibers, the mass fraction of the solid electrolyte particles is Q1, 75wt%≤Q1≤98wt%, the mass fraction of the fibers is Q2, 0wt%<Q2≤5wt%, and the mass fraction of the binder is Q3, 2wt%≤Q3≤20wt%.

6. The electrolyte membrane according to claim 1, characterized in that, The electrolyte membrane further includes an insulating base film layer, the base film layer having a thickness direction, the base film layer having a first surface and a second surface opposite to each other along the thickness direction, wherein at least one surface is provided with the solid electrolyte layer; the base film layer is provided with a through hole, the through hole penetrating the base film layer along the thickness direction.

7. The electrolyte membrane according to claim 6, characterized in that, The diameter of the through hole is D3; D2 < D3, and / or, D3 < L1, and / or, 30μm ≤ D3 ≤ 200μm.

8. The electrolyte membrane according to claim 6, characterized in that, The porosity of the base film layer is P, where 20% ≤ P ≤ 50%.

9. The electrolyte membrane according to claim 6, characterized in that, The base film layer is made of polyethylene, polypropylene, or aramid.

10. The electrolyte membrane according to claim 6, characterized in that, The solid electrolyte layer includes a first solid electrolyte layer and a second solid electrolyte layer, wherein the first solid electrolyte layer is disposed on a first surface and the second solid electrolyte layer is disposed on a second surface.

11. The electrolyte membrane according to claim 10, characterized in that, The fiber comprises a first fiber and a second fiber, the first solid electrolyte layer comprises the first fiber, the second solid electrolyte layer comprises the second fiber, and the diameter of the first fiber is D. 11 The diameter of the second fiber is D 12 And D 12 ≤D 11 ; and / or, the thickness of the second solid electrolyte layer is less than or equal to the thickness of the first solid electrolyte layer.

12. The electrolyte membrane according to claim 11, characterized in that, 5μm≤D 11 ≤14μm; and / or, 100nm≤D 12 ≤10μm.

13. A method for preparing an electrolyte membrane as described in any one of claims 1 to 12, characterized in that, Includes the following steps: The fiber and the solid electrolyte particles are mixed in a solvent to prepare a solid electrolyte slurry. The solid electrolyte slurry is coated onto the surface of the carrier and dried to obtain the electrolyte membrane.

14. The method for preparing the electrolyte membrane according to claim 13, characterized in that, The solvent also contains a binder; the fiber, the binder and the solid electrolyte particles are mixed in the solvent to obtain a solid electrolyte slurry.

15. The method for preparing the electrolyte membrane according to claim 13, characterized in that, The carrier is selected from a temporary carrier, and the preparation method further includes the step of removing the temporary carrier; Alternatively, the carrier may be selected from the base film layer.

16. The method for preparing the electrolyte membrane according to claim 15, characterized in that, The carrier is selected from a base film layer, the base film layer has a thickness direction, and the solid electrolyte slurry is coated on two opposite surfaces of the base film layer along the thickness direction; the two opposite surfaces of the base film layer along the thickness direction are a first surface and a second surface, the solid electrolyte slurry coated on the first surface is a first slurry, and the solid electrolyte slurry coated on the second surface is a second slurry; the fiber comprises a first fiber and a second fiber, and the specific steps of the preparation method are as follows: First, the first fiber and the solid electrolyte particles are mixed in a solvent to prepare a first slurry. The first slurry is then coated onto the first surface and dried. The second fiber and the solid electrolyte particles are then mixed in a solvent to prepare a second slurry. The second slurry is then coated onto the second surface and dried to obtain the electrolyte membrane.

17. The method for preparing the electrolyte membrane according to claim 16, characterized in that, The diameter of the first fiber is D. 11 The length is L1, and the diameter of the second fiber is D. 12 And the length is L1, D 12 ≤D 11 <D2<L1; And / or, the first slurry is dried to form a first solid electrolyte layer, and the second slurry is dried to form a second solid electrolyte layer, wherein the thickness of the second solid electrolyte layer is less than or equal to the thickness of the first solid electrolyte layer.

18. The method for preparing the electrolyte membrane according to claim 16, characterized in that, The solid content of the first slurry is M1, 30% ≤ M1 ≤ 60%; and / or, the solid content of the second slurry is M2, 30% ≤ M2 ≤ 60%.

19. A solid-state battery, characterized in that, The electrode comprises an electrode sheet and an electrolyte membrane according to any one of claims 1 to 12, or the electrode comprises an electrode sheet and an electrolyte membrane prepared by any one of claims 13 to 18; the electrode sheet and the electrolyte membrane are stacked alternately.

20. An electrical appliance, characterized in that, It includes the solid-state battery of claim 19, or includes a battery module, wherein the battery module includes the solid-state battery of claim 19.

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