A "sponge-like" solid electrolyte, its preparation method and application

Abstract

This invention provides a "sponge-like" solid electrolyte, its preparation method, and its application, relating to the field of solid-state battery technology. It includes a solid electrolyte and a saturated "sponge-like" material covering both sides of the solid electrolyte. The saturated "sponge-like" material is obtained by absorbing electrolyte to a saturated state using a porous "sponge-like" material. The saturated "sponge-like" material can undergo elastic deformation under certain pressure, allowing electrolyte to seep out. This invention solves the interface problem between the electrolyte and the electrode by attaching a three-dimensional "sponge-like" material to the surface of the solid electrolyte membrane to adsorb the electrolyte, allowing the electrolyte to seep out under relatively low pressure.

Description

Technical Field

[0001] This invention relates to the field of solid-state battery technology, and in particular to a "sponge" solid electrolyte, its preparation method, and its application. Background Technology

[0002] In solid-state batteries, the solid electrolyte membrane plays a crucial role. Currently, commonly used inorganic solid electrolytes include sulfide solid electrolytes, perovskite solid electrolytes, and halide solid electrolytes. Among them, sulfide solid electrolyte membranes have high ionic conductivity, which can meet the basic performance requirements of battery design. However, the interface problem has long been a challenge hindering the development of solid-state battery technology, mainly due to poor contact between the electrolyte and the electrode and side reactions at the interface. Existing solutions mainly involve using various additives to improve the interfacial contact between the solid electrolyte membrane and the electrode, such as surfactants and binders to increase the contact area and adhesion between the electrolyte and the electrode, and coating the electrode surface with a protective layer to reduce side reactions at the interface. Although the above solutions have improved the interface problem between the electrolyte and the electrode to some extent, some problems and limitations still exist. First, the composition and structure of additives are very complex and varied, making it very difficult to select suitable additives to effectively solve the interface problem, and the additional additives used often have an adverse effect on the battery performance. In addition, although coating the electrode surface with a protective film can reduce side reactions at the interface, it will significantly increase the electrode resistance, thereby increasing the internal polarization impedance of the battery. Furthermore, sulfide solid electrolytes can only operate under relatively high pressures (≥5MPa), which limits their application scenarios.

[0003] In view of this, the present invention is proposed. Summary of the Invention

[0004] The purpose of this invention is to provide a "sponge" solid electrolyte, its preparation method and application. This invention solves the interface problem between the electrolyte and the electrode by attaching a three-dimensional "sponge" material to the surface of the solid electrolyte membrane to adsorb the electrolyte and allowing the electrolyte to seep out under relatively low pressure.

[0005] To achieve the above objectives, the present invention adopts the following technical solution:

[0006] The present invention provides a "sponge" solid electrolyte, comprising a solid electrolyte and a "sponge" material saturated on both sides of the solid electrolyte;

[0007] The saturated "sponge" material is obtained by absorbing electrolyte to a saturated state using a "sponge" material with a porous structure.

[0008] The saturated "sponge" material can undergo elastic deformation under certain pressure, causing the electrolyte to seep out from the "sponge" material.

[0009] Furthermore, based on the above technical solution, the thickness of the porous "sponge" material is 5-200 μm, preferably 25 μm;

[0010] And / or, the porosity of the "sponge" material with a porous structure is 15% to 70%, preferably 40%;

[0011] And / or, the pressure applied to the saturated "sponge" is in the range of 0.2 to 2 MPa, preferably 0.4 MPa.

[0012] Furthermore, based on the above technical solution, the "sponge" material with a porous structure includes one of polyurethane sponge, polyimide sponge, nickel foam, or aluminum foam.

[0013] And / or, the solid electrolyte is an inorganic solid electrolyte;

[0014] The inorganic solid electrolyte is a sulfide solid electrolyte;

[0015] The sulfide solid electrolyte is LiPSCl5.

[0016] Furthermore, based on the above technical solution, the electrolyte is an organic lithium salt electrolyte;

[0017] The organic lithium salt electrolyte comprises an organic lithium salt and a solvent;

[0018] The concentration of the organic lithium salt electrolyte is greater than 1 mol / L;

[0019] The organic lithium salts include N-methyl-N-butylpyrrolidine bis(trifluoromethanesulfonyl)imide, lithium bis(fluoroxanimide), lithium trifluoromethanesulfonate, and lithium tri(trifluoromethanesulfonyl)imide;

[0020] The solvent includes one or more of ethylene carbonate, dimethyl carbonate, ethyl methyl carbonate, and diethyl carbonate.

[0021] Furthermore, based on the above technical solution, the saturated state refers to the state in which the "sponge" material with a porous structure can no longer absorb electrolyte.

[0022] The present invention also provides a method for preparing the "sponge" solid electrolyte as described above, comprising the following steps:

[0023] S1: Pre-treat the "sponge" material with a porous structure;

[0024] S2: Immerse the pretreated "sponge" material in the electrolyte until it is saturated to obtain saturated "sponge" material;

[0025] S3: Cover both sides of the solid electrolyte with saturated "sponge" material to obtain a "sponge" solid electrolyte.

[0026] Furthermore, based on the above technical solution, in step S1, the pretreatment includes selecting the porosity and thickness of the "sponge" material with a porous structure, and cutting it into the same size as the solid electrolyte.

[0027] The present invention also provides a "sponge-like" solid electrolyte prepared by the preparation method of the "sponge-like" solid electrolyte as described above, or the application of the "sponge-like" solid electrolyte as described above, which can be used to assemble with positive and negative electrode sheets in a solid-state battery mold to form a solid-state battery.

[0028] Furthermore, based on the above technical solution, the solid-state battery comprises, from top to bottom: a negative electrode current collector, a negative electrode active material layer, a saturated "sponge" material layer, an inorganic solid electrolyte layer, a saturated "sponge" material layer, a positive electrode active material layer, and a positive electrode current collector.

[0029] The negative electrode sheet consists of a negative electrode current collector and a negative electrode active material layer coated on the surface of the negative electrode current collector.

[0030] The positive electrode current collector and the positive electrode active material layer coated on the surface of the positive electrode current collector constitute the positive electrode sheet;

[0031] The inorganic solid electrolyte layer and the saturated "sponge" material layers on both sides of the inorganic solid electrolyte layer constitute the "sponge" solid electrolyte.

[0032] Furthermore, based on the above technical solution, the positive electrode current collector includes aluminum foil or carbon material;

[0033] The positive electrode active material layer is a high-nickel NCM ternary material;

[0034] And / or, the negative electrode current collector includes one of copper foil, titanium foil, nickel foil, and stainless steel;

[0035] The negative electrode active material layer is made of silicon-carbon material.

[0036] The present invention provides a "sponge-like" solid electrolyte, its preparation method, and its application, with the following beneficial effects:

[0037] 1. Improved Interfacial Contact: This invention solves the interfacial problem between the electrolyte and electrode by attaching a three-dimensional "sponge" material to the surface of the solid electrolyte membrane to adsorb the electrolyte, allowing the electrolyte to seep out under relatively low pressure. Compared to existing technologies that improve the interfacial contact between the electrolyte and electrode by adding various additives, this invention eliminates the need for additives, avoiding adverse effects on the electrochemical performance of the electrolyte. Furthermore, it eliminates the need to optimize the composition and structure of the electrolyte, saving on experimental research and development costs.

[0038] 2. High stability: The "sponge" material in this invention is stable under both high and low voltage conditions, preventing sulfides from contacting the positive and negative electrodes and reducing side reactions at the interface. Compared to existing technologies that reduce side reactions at the interface by coating a protective film on the electrode surface, the "sponge" material of this invention not only reduces side reactions at the interface but also, due to its high stability, can be used in a wider voltage range, improving the stability and lifespan of the battery.

[0039] 3. Electrolyte Leakage: This invention allows the electrolyte to leak out from the "sponge" material under relatively low pressure, ensuring full contact between the electrolyte and the electrodes. Compared to existing technologies that improve the compatibility between the electrolyte and electrodes by optimizing the composition and structure of the electrolyte, this invention uses a physical method to allow the electrolyte to leak out. This method is simple to operate, highly efficient, and can significantly improve battery performance.

[0040] 4. Low cost: The "sponge" material used in this invention is inexpensive, easy to obtain and prepare. Compared to existing technologies that require extensive experimental research and development to optimize the composition and structure of the electrolyte, this technical solution has a significant cost advantage. Compared to existing technologies, this invention not only has a significant advantage in solving the interface problem between the electrolyte and the electrode, but also exhibits outstanding superiority in terms of stability, electrolyte leakage, and cost.

[0041] 5. This invention allows the electrolyte to seep out of the "sponge" material under relatively low pressure, overcoming the limitation that sulfide solid electrolytes can only work under high pressure, and expanding the application range of sulfide solid electrolytes. Attached Figure Description

[0042] To more clearly illustrate the specific embodiments of the present invention or the technical solutions in the prior art, the drawings used in the description of the specific embodiments or the prior art will be briefly introduced below. Obviously, the drawings described below are some embodiments of the present invention. For those skilled in the art, other drawings can be obtained from these drawings without creative effort.

[0043] Figure 1 This is a schematic diagram of the structure of the mold battery provided by the present invention;

[0044] Icon labels:

[0045] 1. Negative electrode current collector; 2. Negative electrode active material layer; 3. Saturated "sponge" material layer; 4. Inorganic solid electrolyte layer; 5. Positive electrode active material layer; 6. Positive electrode current collector. Detailed Implementation

[0046] To make the objectives, technical solutions, and advantages of this invention clearer, the technical solutions in the embodiments of this invention will be clearly and completely described below in conjunction with the embodiments of this invention. Those skilled in the art should understand that the embodiments described are merely illustrative of the invention and should not be considered as specific limitations thereof. All other embodiments obtained by those skilled in the art based on the embodiments of this invention without creative effort are within the scope of protection of this invention. Process parameters not specifically specified in the following embodiments are generally performed under conventional conditions.

[0047] The endpoints and any values ​​of the ranges disclosed in this invention are not limited to the precise ranges or values, and these ranges or values ​​should be understood to include values ​​close to these ranges or values. For numerical ranges, the endpoint values ​​of the various ranges, the endpoint values ​​of the various ranges and individual point values, and individual point values ​​can be combined with each other to obtain one or more new numerical ranges, which should be considered as specifically disclosed in this invention.

[0048] According to a first aspect of the present invention, a "sponge" solid electrolyte is provided, comprising a solid electrolyte and a "sponge" material saturated on both sides of the solid electrolyte;

[0049] The saturated "sponge" material is obtained by absorbing electrolyte to a saturated state using a "sponge" material with a porous structure.

[0050] The saturated "sponge" material can undergo elastic deformation under certain pressure, causing the electrolyte to seep out from the "sponge" material.

[0051] Specifically, this invention causes the electrolyte to seep out from a "sponge" material under pressure, ensuring full contact between the electrolyte and the electrodes. Compared to existing technologies that improve the compatibility between the electrolyte and electrodes by optimizing the composition and structure of the electrolyte, this technical solution uses a physical method to cause the electrolyte to seep out, which is simple to operate, highly efficient, and can significantly improve battery performance.

[0052] As an optional embodiment of the present invention, the thickness of the porous "sponge" material is 5-200 μm (e.g., 10 μm, 20 μm, 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, etc.), preferably 25 μm;

[0053] The porosity of the "sponge" material with a porous structure is 15% to 70% (e.g., 20%, 30%, 40%, 45%, 50%, 55%, 60%, 65%, etc.), preferably 40%;

[0054] The pressure applied to the saturated "sponge" is in the range of 0.2 to 2 MPa (e.g., 0.4 MPa, 0.6 MPa, 0.8 MPa, 1.0 MPa, 1.2 MPa, 1.4 MPa, 1.6 MPa, 1.8 MPa, etc.), preferably 0.4 MPa.

[0055] Specifically, attaching a three-dimensional saturated "sponge" material to the surface of an inorganic solid electrolyte allows the electrolyte to seep out under pressure, thereby improving the contact between the electrolyte and the electrodes. The porous "sponge" material is stable under both high and low voltage conditions. Attached to the surface of the solid electrolyte membrane, it effectively isolates the electrolyte and electrodes, reducing side reactions at the interface and thus improving battery performance and lifespan. The amount of electrolyte absorbed can be controlled by adjusting the porosity and thickness of the porous "sponge" material; the amount of electrolyte extruded can be controlled by adjusting the applied pressure, allowing the electrolyte to seep out within the "sponge" material. This creates good contact between the electrolyte and the electrodes without increasing electrode resistance, effectively improving battery performance.

[0056] Furthermore, if the thickness of the porous "sponge" material is less than 5 μm or its porosity is less than 15%, it limits the "sponge" material's ability to store electrolyte, resulting in a significant reduction in the amount of electrolyte that can be absorbed. This insufficient amount of electrolyte makes it difficult to fully wet the surfaces of the electrodes and electrolyte membrane, leading to a restricted ion conduction pathway and thus affecting battery performance.

[0057] If the thickness of a porous "sponge" material is greater than 200 μm or the porosity is greater than 70%, a large amount of space inside the "sponge" material will not be effectively utilized. Although these spaces can store electrolyte, most of the electrolyte may not effectively participate in the ion transport process during battery operation, thereby reducing the energy efficiency and economy of the battery and wasting electrolyte.

[0058] If the pressure applied to the saturated "sponge" material is less than 0.2 MPa, it cannot be ensured that the electrolyte in the "sponge" can be evenly and effectively distributed on the electrolyte surface. This uneven electrolyte distribution will lead to an increase in the internal resistance of the battery, affecting the uniform transmission of current and thus reducing the overall performance of the battery.

[0059] If the pressure applied to the saturated "sponge" material exceeds 2 MPa, excessive compression may occur, forcing the "sponge" to release too much electrolyte. This excessive release of electrolyte not only wastes resources but may also cause changes in the internal structure of the battery, such as the shedding of electrode materials or damage to the electrolyte membrane, thereby threatening the safety and lifespan of the battery.

[0060] As an optional embodiment of the present invention, the "sponge" material with a porous structure includes one of polyurethane sponge, polyimide sponge, nickel foam, or aluminum foam;

[0061] Specifically, the reason for using the materials mentioned above as "sponge" materials is that these materials have high stability, do not react with the electrolyte, and do not react under high / low voltage conditions, thus having no impact on battery performance. In addition, these materials have high thermal stability, with a thermal decomposition temperature above 350°C, resulting in high battery safety.

[0062] And / or, the solid electrolyte is an inorganic solid electrolyte, and the inorganic solid electrolyte is a sulfide solid electrolyte;

[0063] Preferably, the sulfide solid electrolyte is LiPSCl5.

[0064] As an optional embodiment of the present invention, the electrolyte is an organic lithium salt electrolyte;

[0065] Preferably, the organic lithium salt electrolyte comprises an organic lithium salt and a solvent;

[0066] Preferably, the concentration of the organic lithium salt electrolyte is greater than 1 mol / L;

[0067] Preferably, the organolithium salt comprises one or more of N-methyl-N-butylpyrrolidine bis(trifluoromethanesulfonyl)imide, lithium bis(fluoroxanthione)imide, lithium trifluoromethanesulfonate, and lithium tri(trifluoromethanesulfonyl)imide.

[0068] Preferably, the solvent includes one or more of ethylene carbonate, dimethyl carbonate, ethyl methyl carbonate, and diethyl carbonate.

[0069] As an optional embodiment of the present invention, a saturated state refers to a state in which a certain property or capability of an object or system reaches its maximum limit and cannot be increased or improved further; in the present invention, the saturated state refers to a state in which a "sponge" material with a porous structure can no longer absorb electrolyte.

[0070] According to a second aspect of the present invention, a method for preparing the "sponge" solid electrolyte as described above is provided, comprising the following steps:

[0071] S1: Pre-treat the "sponge" material with a porous structure;

[0072] S2: Immerse the pretreated "sponge" material in the electrolyte until it is saturated to obtain saturated "sponge" material;

[0073] S3: Cover both sides of the solid electrolyte with saturated "sponge" material to obtain a "sponge" solid electrolyte.

[0074] As an optional embodiment of the present invention, in step S1, the pretreatment includes selecting the porosity and thickness of the "sponge" material with a porous structure, and cutting it into the same size as the solid electrolyte.

[0075] As an optional embodiment of the present invention, in step S2, the saturated state is the state in which the pretreated "sponge" material can no longer absorb electrolyte.

[0076] As an optional embodiment of the present invention, in step S3, the solid electrolyte is prepared into a membrane by a dry method and pressed under a pressure of 400 MPa during use, so that the solid electrolyte membrane is denser and has no pores, and cannot be permeated by electrolyte.

[0077] According to a third aspect of the present invention, an application is provided of a "sponge-like" solid electrolyte as described above or a "sponge-like" solid electrolyte prepared by the preparation method of the "sponge-like" solid electrolyte as described above, which can be used to assemble with a positive electrode and a negative electrode in a solid-state battery mold to form a solid-state battery.

[0078] Specifically, during the assembly process, the mass of the positive and negative electrodes may exert pressure on the saturated "sponge" solid electrolyte. However, this pressure will not cause the electrolyte to overflow from the saturated "sponge". Therefore, after the battery is assembled, when testing the battery, pressure is applied to the "sponge" solid electrolyte through a pressure sensor inside the solid battery mold. This causes the "sponge" solid electrolyte to deform, thereby causing the electrolyte to overflow from the saturated "sponge" and wet the surfaces of the positive and negative electrodes, thus improving the interfacial contact.

[0079] As an optional embodiment of the present invention, in the solid-state battery, such as Figure 1 As shown, from top to bottom, they are: negative electrode current collector 1, negative electrode active material layer 2, saturated "sponge" material layer 3, inorganic solid electrolyte layer 4, saturated "sponge" material layer 3, positive electrode active material layer 5, and positive electrode current collector 6.

[0080] Among them, the negative electrode current collector 1 and the negative electrode active material layer 2 coated on the surface of the negative electrode current collector constitute the negative electrode sheet;

[0081] The positive electrode current collector 6 and the positive electrode active material layer 5 coated on the surface of the positive electrode current collector constitute the positive electrode sheet;

[0082] The inorganic solid electrolyte layer 4 and the saturated "sponge" material layers 3 on both sides of the inorganic solid electrolyte layer 4 constitute the "sponge" solid electrolyte.

[0083] As an optional embodiment of the present invention, the positive current collector includes aluminum foil, carbon materials, etc.

[0084] The positive electrode active material layer is a high-nickel NCM ternary material.

[0085] As an optional embodiment of the present invention, the negative electrode current collector includes copper foil, titanium foil, nickel foil, stainless steel, etc.

[0086] The negative electrode active material layer is made of silicon-carbon (Si-C).

[0087] The present invention will now be described in further detail with reference to specific embodiments and comparative examples.

[0088] Example 1

[0089] Preparation of sulfide (LiPSCl5) solid electrolyte:

[0090] The membrane is prepared by dry process and has a diameter of φ19mm and a thickness of 65μm. It is pressed under a pressure of 400MPa during use, which makes the solid electrolyte membrane more compact and non-porous, and prevents the electrolyte from permeating.

[0091] Preparation of "sponge-like" solid electrolytes:

[0092] (1) Select a polyurethane “sponge” material with a porosity of 40% (a “sponge” material with a porous structure), cut it into a size of φ19mm in diameter and 25μm in thickness, so that it can cover the surface of the sulfide solid electrolyte membrane.

[0093] (2) Soak the cut polyurethane sponge in the electrolyte of N-methyl-N-butylpyrrolidine bis(trifluoromethanesulfonyl)imide salt for 5 minutes. After it fills the electrolyte to saturation, leave it for later use.

[0094] In this process, N-methyl-N-butylpyrrolidine bis(trifluoromethanesulfonyl)imide salt is placed in ethylene carbonate to prepare an organic lithium salt electrolyte with a concentration of 2 mol / L.

[0095] (3) The soaked polyurethane sponge (saturated "sponge" material) is covered on both sides of the sulfide solid electrolyte membrane to obtain the "sponge" solid electrolyte.

[0096] Fabrication of solid-state batteries using fully sealed molds:

[0097] The obtained "sponge" solid electrolyte, positive electrode, and negative electrode are assembled in a solid battery mold. A pressure of 0.4 MPa is applied by a pressure sensor to deform the "sponge" solid electrolyte, causing the electrolyte to seep out. The seeping electrolyte can wet the surface of the electrode and improve the contact between the solid electrolyte and the electrode.

[0098] The positive electrode sheet was prepared by uniformly mixing high-nickel NCM ternary material with PVDF, SP, and CNT in a mass ratio of 96.5:2.0:1.0:0.5 and coating it evenly onto a 13μm carbon-coated aluminum foil to obtain an areal density of 190mg / 10cm³. 2 The positive electrode plate;

[0099] Preparation of the negative electrode: Silicon-carbon, SP, CMC, and SBR were mixed uniformly in a mass ratio of 94:2:1.5:2.5 and then uniformly coated onto a 6μm copper foil to obtain an areal density of 90mg / 10cm². 2 The negative electrode plate;

[0100] In a solid-state battery mold, the components from top to bottom are: negative electrode, "sponge" solid electrolyte, and positive electrode, which are assembled into a fully sealed mold solid-state battery.

[0101] Examples 2-8

[0102] The preparation methods in Examples 2-8 are the same as those in Example 1. The technical parameters and operations that differ from those in Example 1 are shown in Table 1.

[0103] Comparative Example 1

[0104] The sulfide (LiPSCl5) solid electrolyte, the positive electrode and the negative electrode prepared in Example 1 were directly assembled in a solid battery mold without applying pressure or adding electrolyte, as shown in Table 1.

[0105] Comparative Example 2

[0106] The sulfide (LiPSCl5) solid electrolyte, the positive electrode and the negative electrode prepared in Example 1 were directly assembled in a solid battery mold, and a pressure of 5 MPa was applied without adding electrolyte, as shown in Table 1.

[0107] Comparative Example 3

[0108] The sulfide (LiPSCl5) solid electrolyte, the positive electrode and the negative electrode prepared in Example 1 were directly assembled in a solid battery mold, a pressure of 0.4 MPa was applied, and 2 drops of the electrolyte in Example 1 were added, as shown in Table 1.

[0109] Comparative Examples 4-7

[0110] The preparation methods in Comparative Examples 4-7 are the same as in Example 1, and the technical parameters and operations that differ from those in Example 1 are shown in Table 1.

[0111] Table 1

[0112]

[0113] Performance testing

[0114] The performance tests of the fully sealed mold solid-state batteries prepared in the above embodiments and comparative examples specifically include:

[0115] Battery capacity retention

[0116] Capacity retention rate refers to the ratio of a battery's discharge capacity to its initial discharge capacity after a certain period of time or a certain number of cycles. It is usually expressed as a percentage. The battery capacity retention rate test is performed on the prepared battery, and the specific test method includes the following steps:

[0117] 1) Initial discharge capacity test: First, within the voltage range of 2.5-4.2V, the first charge and discharge test is carried out at 0.1C to obtain the initial discharge capacity of the battery;

[0118] 2) Cycling: Charge and discharge tests were conducted at 0.2C charging and 0.2C discharging, with an initial discharge capacity of C0;

[0119] 3) Re-discharge test: After 30 cycles of the test, the battery is charged again at 0.2C and discharged at 0.2C to obtain the discharge capacity C1 at this time;

[0120] Calculate the capacity retention rate: Based on the definition of capacity retention rate, which is the ratio of C1 to C0, the capacity retention rate of the battery is calculated.

[0121] A higher capacity retention rate indicates more stable battery performance and a longer lifespan.

[0122] Coulombic efficiency of battery

[0123] The coulombic efficiency of a battery refers to the ratio of output charge to input charge during charging and discharging, usually expressed as a percentage. The coulombic efficiency test of the prepared battery includes the following steps:

[0124] 1) Preparation stage: Place the battery in the temperature chamber and connect the battery and the test equipment using a four-wire connection. Set the temperature chamber temperature to 35℃ to simulate the temperature conditions of the actual working environment.

[0125] 2) Connect the test equipment: Ensure that the battery is correctly connected to the test equipment in order to conduct subsequent charge and discharge tests;

[0126] 3) Charge / discharge test: Perform charge / discharge tests on the battery according to the requirements of the testing equipment. Record the battery's input charge during charging and the battery's output charge during discharging.

[0127] The Coulomb efficiency is calculated based on the recorded ratio of output charge to input charge.

[0128] The higher the coulombic efficiency, the less charge loss the battery experiences during charging and discharging, and the better its performance.

[0129] The test results are shown in Table 2:

[0130] Table 2

[0131]

[0132]

[0133] As shown in Comparative Example 1 in Table 2, in solid-state batteries, without the addition of sponge material and electrolyte, and with an applied pressure of 0, the interfacial contact between the electrode and the electrolyte membrane is poor, the battery impedance is high, the battery performance cannot be fully utilized, and the battery cycle performance is poor.

[0134] As shown in Comparative Example 2 in Table 2, in solid-state batteries, when no "sponge" material is added to both sides of the solid electrolyte membrane, a larger pressure is required to improve the interfacial contact between the membrane and the electrodes.

[0135] As shown in Comparative Example 3 in Table 2, in solid-state batteries, adding electrolyte directly at the interface will result in uneven distribution of electrolyte at the interface and poor battery performance.

[0136] As shown in Comparative Example 4 and Example 3 in Table 2, in solid-state batteries, when the porosity of the "sponge" material is large, the amount of electrolyte used will increase, and the ability of the pores to bind the electrolyte will weaken, leading to easy loss of electrolyte during cycling and a decrease in battery cycle performance.

[0137] As shown in Comparative Example 5 in Table 2, in solid-state batteries, when the thickness of the "sponge" material is large, there is a large amount of unused space inside the "sponge" material, which prevents most of the electrolyte from effectively participating in the ion transport process, thereby reducing the energy efficiency and cycle performance of the battery and causing waste of electrolyte.

[0138] As shown in Comparative Example 6 in Table 2, in solid-state batteries, when the pressure applied to the "sponge" material is too high, an excessive compression effect is generated, forcing the "sponge" to release too much electrolyte. This excessive release of electrolyte not only wastes resources, but may also cause changes in the internal structure of the battery, threatening the safety and lifespan of the battery.

[0139] As shown in Comparative Example 7 in Table 2, in solid-state batteries, when the "sponge" material is not saturated with electrolyte, the electrolyte cannot overflow from the "sponge" material when the applied pressure is 0.4 MPa. The interface contact between the electrode and the electrolyte membrane is poor, the battery impedance is high, the battery performance cannot be normalized, and the battery cycle performance is poor.

[0140] In summary, using a "sponge" to absorb electrolyte has little impact on the use of sponge materials and can improve the interfacial contact of a single cell without requiring too much pressure, thus reducing energy loss during battery manufacturing. Porosity and material thickness affect the amount of electrolyte absorbed. Too low porosity and too thin a material result in less electrolyte absorption, failing to fully wet the electrode and electrolyte membrane surfaces, thus affecting battery performance. Excessive porosity and a thick "sponge" material absorb too much electrolyte, leading to some electrolyte waste.

[0141] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention, rather than to limit it. Although the present invention has been described in detail with reference to the above embodiments, those skilled in the art should understand that they can still modify the technical solutions described in the above embodiments, or replace some or all of the technical features therein with equivalents. However, these modifications or replacements do not cause the essence of the corresponding technical solutions to deviate from the scope of the technical solutions of the embodiments of the present invention.

Claims

1. A "sponge-like" solid electrolyte, characterized in that, This includes solid electrolytes and "sponge" materials saturated on both sides of the solid electrolyte; The saturated "sponge" material is obtained by absorbing electrolyte to a saturated state using a "sponge" material with a porous structure. The saturated "sponge" material can undergo elastic deformation under certain pressure, causing the electrolyte to seep out from the "sponge" material; The pressure applied to the saturated "sponge" ranges from 0.2 to 2 MPa.

2. The "sponge" solid electrolyte according to claim 1, characterized in that, The thickness of the porous "sponge" material is 5~200μm; And / or, the porosity of the "sponge" material with a porous structure is 15% to 70%; And / or, the pressure applied to the saturated "sponge" is 0.4 MPa.

3. The "sponge" solid electrolyte according to claim 2, characterized in that, The solid electrolyte has a porous "sponge" material with a thickness of 25 μm.

4. The "sponge" solid electrolyte according to claim 2, characterized in that, The porosity of the "sponge" material with a porous structure is 40%.

5. The "sponge" solid electrolyte according to claim 1, characterized in that, The porous "sponge" material includes one of polyurethane foam, polyimide foam, nickel foam, or aluminum foam. And / or, the solid electrolyte is an inorganic solid electrolyte; The inorganic solid electrolyte is a sulfide solid electrolyte; The sulfide solid electrolyte is LiPSCl5.

6. The "sponge" solid electrolyte according to claim 1, characterized in that, The electrolyte is an organic lithium salt electrolyte; The organic lithium salt electrolyte comprises an organic lithium salt and a solvent; The concentration of the organic lithium salt electrolyte is greater than 1 mol / L; The organolithium salts include N-methyl-N-butylpyrrolidine bis(trifluoromethanesulfonyl)imide, lithium bis(fluoroxanimide), lithium trifluoromethanesulfonate, and lithium tri(trifluoromethanesulfonyl)imide; The solvent includes one or more of ethylene carbonate, dimethyl carbonate, ethyl methyl carbonate, and diethyl carbonate.

7. The "sponge" solid electrolyte according to claim 1, characterized in that, The saturated state refers to the state in which a porous "sponge" material can no longer absorb electrolyte.

8. A method for preparing a "sponge-like" solid electrolyte as described in any one of claims 1-7, characterized in that, Includes the following steps: S1: Pre-treat the "sponge" material with a porous structure; S2: Immerse the pretreated "sponge" material in the electrolyte until saturation to obtain saturated "sponge" material; S3: Cover both sides of the solid electrolyte with saturated "sponge" material to obtain a "sponge" solid electrolyte.

9. The method for preparing the "sponge" solid electrolyte according to claim 8, characterized in that, In step S1, the pretreatment includes selecting the porosity and thickness of the "sponge" material with a porous structure and cutting it into the same size as the solid electrolyte.

10. The application of a "sponge-like" solid electrolyte prepared by the preparation method of the "sponge-like" solid electrolyte as described in any one of claims 8-9, or the "sponge-like" solid electrolyte as described in any one of claims 1-7, characterized in that, It can be used to assemble with positive and negative electrode plates in a solid-state battery mold to form a solid-state battery.

11. The application according to claim 10, characterized in that, In the solid-state battery, from top to bottom, there are: negative electrode current collector, negative electrode active material layer, saturated "sponge" material layer, inorganic solid electrolyte layer, saturated "sponge" material layer, positive electrode active material layer and positive electrode current collector; The negative electrode sheet consists of a negative electrode current collector and a layer of negative electrode active material coated on the surface of the negative electrode current collector. The positive electrode current collector and the positive electrode active material layer coated on the surface of the positive electrode current collector constitute the positive electrode sheet; The inorganic solid electrolyte layer and the saturated "sponge" material layers on both sides of the inorganic solid electrolyte layer constitute the "sponge" solid electrolyte.

12. The application according to claim 11, characterized in that, The positive electrode current collector includes aluminum foil or carbon material; The positive electrode active material layer is a high-nickel NCM ternary material; And / or, the negative electrode current collector includes one of copper foil, titanium foil, nickel foil, and stainless steel; The negative electrode active material layer is made of silicon-carbon material.

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