All-solid-state battery capable of preventing short circuit

Abstract

The utility model provides an all-solid-state battery capable of preventing short circuit, and relates to the technical field of solid-state batteries. The short-circuit-preventing electrolyte membrane comprises a solid electrolyte central area and an insulating material inert insulating frame, the inert insulating frame surrounds the outer side of the solid electrolyte central area, under the external pressure condition, the inert insulating frame plays a role in hardening and supporting and can slightly overflow, and when the short-circuit-preventing electrolyte membrane is used for assembling a battery cell, the short-circuit-preventing electrolyte membrane is not damaged. The sizes of the positive pole piece and the negative pole piece which are overlapped can be kept consistent, so that the pole pieces are not easy to misplace during lamination assembly and pressurization test, and the operation process is easier; under the external pressure, the positive pole piece and the negative pole piece in the battery cell are uniformly stressed, so that the pressing penetration phenomenon caused by edge stress is not easy to occur, the edge fragmentation problem can be avoided, the short circuit of the battery is avoided, and the battery cell assembly success rate is greatly improved. In addition, the inert insulating frame can play a flame-retardant role to a certain extent.

Description

Technical Field

[0001] This utility model relates to the field of solid-state battery technology, specifically to an all-solid-state battery that prevents short circuits and prevents contact between the edges of the battery cell or electrode assembly. Background Technology

[0002] All-solid-state batteries, which use solid electrolytes instead of traditional liquid electrolytes, combine high energy density, high power density, and high safety, and are expected to meet the needs of more life scenarios. They are considered a key direction for future industry development.

[0003] In solid-state batteries, to prevent lithium edge deposition, the negative electrode is typically larger than the positive electrode. On one hand, due to material limitations, the contact resistance between solid-solid materials is much greater than that between liquid-solid materials. To minimize this impact, external forces (10-300 MPa) are applied during assembly and testing of solid-state batteries. This can easily cause electrode breakage due to uneven stress at the edges where electrode sizes differ, leading to short circuits caused by contact between the positive and negative electrode edges. On the other hand, during multi-layer stacking, it is difficult for each smaller electrode to be perfectly aligned in the stacking direction, easily resulting in misalignment, which complicates the production of cells or electrode assemblies. Utility Model Content

[0004] The purpose of this invention is to provide an all-solid-state battery that prevents short circuits. A short-circuit-resistant solid electrolyte membrane is designed to enable the assembly of positive and negative electrodes of the same size. During the assembly process, electrode misalignment is less likely to occur (when electrodes are assembled in different sizes, the positive electrode needs to be centered on the negative electrode as much as possible. During the alternating stacking of electrodes, relative displacement may occur between the electrodes due to equipment vibration, electrode bending, shaking, or other factors, and this is difficult to adjust, affecting the final energy density. With same-size assembly, the positive and negative electrodes are easily aligned, and misalignment is less likely to occur or is easier to adjust), greatly reducing operational difficulty. Simultaneously, the electrodes inside the cell can be evenly stressed, preventing pressure breakdown caused by edge stress, avoiding the circumferential cutting problem of high-strength positive electrode sheets, suppressing edge breakage, and improving the cell assembly success rate.

[0005] In order to achieve the above-mentioned objectives of this utility model, the following technical solution is adopted:

[0006] In a first aspect, the present invention provides an all-solid-state battery that prevents short circuits, comprising: a short-circuit-proof solid electrolyte membrane and alternatingly stacked positive and negative electrodes, wherein the short-circuit-proof solid electrolyte membrane is located between the positive and negative electrodes;

[0007] The short-circuit protection solid electrolyte membrane includes a solid electrolyte central region and an inert insulating frame surrounding the solid electrolyte central region.

[0008] The solid electrolyte membrane is designed to prevent short circuits, and the positive and negative electrodes are of the same size.

[0009] As described in the background art, unlike liquid electrolytes, all-solid-state batteries usually require additional pressure to improve the solid-solid interface contact inside the battery. When the pressure is too high, the space between the positive and negative electrodes at the edges is deeply squeezed, which can easily lead to edge stress causing the electrode to break or even break.

[0010] Based on this, see Figure 1 To solve the above problems, this utility model provides a short-circuit resistant solid electrolyte membrane, which is composed of a solid electrolyte central region 10 and an inert insulating frame 20.

[0011] Furthermore, the central region of the solid electrolyte is completely and seamlessly surrounded by an inert insulating frame.

[0012] Preferably, the thickness 'a' of the solid electrolyte central region and the thickness 'b' of the inert insulating frame satisfy the following condition: 0 ≤ ba ≤ 30 μm. That is, the thicknesses of the solid electrolyte central region and the inert insulating frame are the same, or the coating thickness of the inert insulating frame is slightly higher than the coating thickness of the solid electrolyte central region.

[0013] Furthermore, the central region of the solid electrolyte is rectangular, and the width of the inert insulating frame is 1 to 15 mm, preferably 4 to 8 mm.

[0014] Preferably, see Figure 2 The width L1 of the inert insulating frame along its length is 1mm ≤ L1 ≤ 15mm, and the width L2 of the inert insulating frame along its width is 1mm ≤ L2 ≤ 15mm. Preferably, L1 = L2.

[0015] The solid electrolyte core region is the solid electrolyte material region, which can be a polymer-type solid electrolyte material region, a perovskite-type solid electrolyte material region, an anti-perovskite-type solid electrolyte material region, an oxide solid electrolyte material region, a NASICON-type solid electrolyte material region, a LISICON-type solid electrolyte material region, a halide solid electrolyte material region, a sulfide solid electrolyte material region, etc.

[0016] An inert insulating frame is a four-frame structure that serves an insulating function. It can be a thermosetting polymer frame, such as a rubber frame, a polypropylene (PP) frame, a polyoxymethylene (POM) resin frame, an epoxy resin frame, a polycarbonate (PC) plastic frame, an epoxy phenolic resin frame, a polyamide / nylon (PA) frame, a polyimide frame, a polystyrene (PS) frame, a cyanate ester frame, a bismaleimide frame, a vinyl ester frame, a polyester resin frame, a polyurethane frame, a polyurea / polyurethane hybrid frame, a phenolic resin frame, a thermosetting plastic frame, a urea-formaldehyde resin frame, a melamine resin frame, etc.

[0017] The dimensions of the positive and negative electrodes are consistent with the dimensions of the short-circuit-protected solid electrolyte membrane.

[0018] There are no special restrictions on the cathode material; cathodes known in the field can be used, such as ternary material cathodes, lithium iron phosphate cathodes, lithium cobalt oxide cathodes, lithium manganese iron phosphate cathodes, lithium-rich manganese-based material cathodes, etc.

[0019] There are no special restrictions on the negative electrode; any negative electrode known in the art can be used, such as carbon negative electrodes (e.g., conductive carbon black, carbon nanotubes, graphene, fullerene, carbon nanofiber negative electrodes), silicon negative electrodes, tin negative electrodes, lithium metal negative electrodes, etc.

[0020] The solid electrolyte central region is formed by coating with solid electrolyte slurry; the inert insulating frame is formed by coating with thermosetting insulating material (thermosetting polymer) on the outside of the solid electrolyte central region.

[0021] The aforementioned all-solid-state battery that prevents short circuits can be prepared by the following method:

[0022] (1) An inert insulating frame is formed on the substrate layer;

[0023] (2) A solid electrolyte slurry is coated inside an inert insulating frame to form a solid electrolyte central region. After drying, it is pressed and peeled off from the substrate to obtain a short-circuit-proof solid electrolyte membrane.

[0024] (3) The positive and negative electrode sheets are cut to the same size as the short-circuit-proof solid electrolyte membrane;

[0025] (4) The positive electrode, the short-circuit protection solid electrolyte membrane, and the negative electrode are stacked in sequence from top to bottom to form a battery cell or electrode assembly. The assembled battery cell structure is as follows: Figure 3 As shown;

[0026] (5) Apply additional pressure to the cell or electrode assembly along the stacking direction to obtain a solid-state battery that prevents short circuits. The cell structure after being subjected to the force is as follows: Figure 4 As shown.

[0027] The base layer can be PET film, PP film, PE film, aluminum foil, nickel foil, etc.;

[0028] Step (1) specifically involves using a glue gun to apply thermosetting polymer emulsion / high-concentration solution or heated thermosetting polymer fluid onto the substrate layer, and then drying it to form a frame structure.

[0029] Step (2) Prepare solid electrolyte slurry: Weigh solid electrolyte powder, add binder and solvent, and mix and disperse the mixture using a double planetary mixer to obtain slurry.

[0030] Solid electrolyte slurry is obtained by dispersing / dissolving a solid electrolyte and a binder in a solvent. Taking a sulfide electrolyte as an example, the binder includes any one or a combination of at least two of the following: butadiene rubber, styrene-butadiene rubber (SBR), nitrile rubber (NBR), styrene-butadiene-styrene block copolymer (SBS), hydrogenated styrene-butadiene rubber, hydrogenated nitrile rubber, polyimide (PI), and polyvinylidene fluoride (PVDF), more preferably styrene-butadiene rubber (SBR) or nitrile rubber (NBR). The solvent includes one or more of toluene, xylene, anisole, butyl butyrate, n-heptane, pentane, hexane, octane, cyclohexane, cyclohexanone, methylcyclohexanone, chlorobenzene, dichlorobenzene, dichloromethane, methanol, ethanol, isopropanol, diethyl ether, propylene oxide, methyl acetate, ethyl acetate, propyl acetate, acetone, methyl butyl ketone, methyl isobutyl ketone, ethylene glycol monomethyl ether, ethylene glycol monoethyl ether, ethylene glycol monobutyl ether, and acetonitrile; preferably one or more of toluene, xylene, anisole, and n-heptane.

[0031] The above slurry is applied to the frame structure, and then transferred to an oven to remove the solvent.

[0032] The electrolyte membrane was pressed at 30°C and 10MPa for 1 minute to peel off the substrate layer, forming a short-circuit-resistant solid electrolyte membrane.

[0033] Step (5) The positive electrode, the anti-short-circuit solid electrolyte membrane, and the negative electrode are stacked in turn from top to bottom to form a cell or electrode assembly. An additional pressure is applied to the cell or electrode assembly along the stacking direction. The additional pressure is 2-500 MPa, preferably 150-400 MPa.

[0034] Technical effects:

[0035] 1) The anti-short-circuit solid electrolyte membrane in this utility model has both the ion conduction function of the solid electrolyte central region and the anti-short-circuit function of the inert insulating frame;

[0036] 2) The inert insulating frame fills the space gap between the positive and negative electrodes at their edges, preventing the electrodes from breaking or being crushed due to edge stress. At the same time, it enables the positive and negative electrodes to be assembled of the same size, which is easy for stacking operations. The wide planar contact between the electrodes (mutual support can be generated at the edges of the electrodes) effectively weakens the shearing effect inside the cell or electrode assembly, and improves the success rate of cell assembly.

[0037] 3) The insulating material in the inert insulating frame will undergo slight extrusion deformation and overflow after being pressurized, further restricting the edge contact of the positive and negative electrode sheets.

[0038] The present invention has been described in detail above; however, the above embodiments are merely illustrative and are not intended to limit the present invention. Furthermore, this document is not limited to the foregoing prior art or the content of the present invention, or any theory described in the following embodiments. Attached Figure Description

[0039] Figure 1 This is a schematic diagram of the structure of the anti-short-circuit solid electrolyte membrane in this utility model;

[0040] Figure 2 This is a schematic diagram showing the width of the inert insulating frame;

[0041] Figure 3 This is a schematic diagram of the battery cell assembled using a short-circuit-resistant solid electrolyte membrane in this utility model;

[0042] Figure 4 This is a schematic diagram of the structure of the battery cell assembled with a short-circuit-proof solid electrolyte membrane in this utility model after being subjected to pressure.

[0043] Diagram: 10 - Solid electrolyte central region; 20 - Inert insulating frame; 100 - Positive electrode; 200 - Negative electrode. Detailed Implementation

[0044] The present invention will be further described below with reference to the embodiments. It should be noted that the following embodiments are provided for illustrative purposes only and do not constitute a limitation on the scope of protection of the present invention.

[0045] Unless otherwise specified, the raw materials, reagents, and methods used in the embodiments are all conventional raw materials, reagents, and methods in the art.

[0046] Example 1

[0047] Using a glue gun, 90℃ insulating elastic polyurethane (Wanhua WHT-6290) is extruded and coated onto a PET film substrate. After vacuum curing and drying at room temperature, a frame structure is formed with an internal size of 4×6cm, L1 and L2 frame widths of 10mm, and a thickness of 63μm.

[0048] Prepare a sulfide solid electrolyte slurry with a certain proportion: Weigh 1.96g of LPSCl electrolyte powder, add 0.04g of SBS and 2g of toluene solution, and mix for half an hour using a double planetary mixer to obtain the slurry. Pour the above slurry onto the inside of a doctor blade and coat it in a 4×6cm area inside the frame structure. Maintain the ambient dew point temperature at -50℃ to -60℃. After coating, transfer it to a 60℃ oven for 5 hours to remove the toluene solvent. The film thickness is 60±2μm. Press the above electrolyte film at 30℃ and 10MPa pressure for 1 minute, peel off the substrate, and form the electrolyte film.

[0049] Example 2

[0050] The difference from Example 1 is that the polyurethane is replaced with polyimide resin (water content <0.1%, viscosity >20000mPa·S, molecular weight 50000), which is cured and dried under high temperature and vacuum to form a frame structure.

[0051] Example 3

[0052] The difference from Example 1 is that the polyurethane is replaced with vinyl ester resin (INEOS Derakane 8084), which is cured and dried at high temperature and vacuum to form a frame structure.

[0053] Example 4

[0054] The difference from Example 1 is that the elastic polyurethane coating thickness is 60 micrometers.

[0055] Example 5

[0056] The difference from Example 1 is that the elastic polyurethane coating thickness is 65 micrometers.

[0057] Example 6

[0058] The difference from Example 1 is that 1.96g of Li was weighed. 5.3 PS 4.3 ClBr 0.7 Add 0.04g SBS and 2g toluene solution to the electrolyte powder.

[0059] Example 7

[0060] The difference from Example 1 is that the frame widths of L1 and L2 are 2mm.

[0061] Example 8

[0062] The difference from Example 1 is that the frame widths of L1 and L2 are 8mm.

[0063] Example 9

[0064] The difference from Example 1 is that the internal frame structure and coating size are 6×8cm.

[0065] Comparative Example 1

[0066] The difference from Example 1 is that a sulfide electrolyte slurry with a size of 4×6cm is directly coated on the substrate to form an electrolyte membrane.

[0067] Comparative Example 2

[0068] The difference from Comparative Example 1 is that the coating size is 6×8cm.

[0069] Comparative Example 3

[0070] The difference from Comparative Example 1 is that, in the assembly process of the pouch cell, the size of the positive electrode is smaller than that of the negative electrode.

[0071] Four-positive-five-negative solid-state pouch cells were assembled using the electrolyte membranes, ternary NCM811 positive electrodes, and silicon-oxygen negative electrodes of the same size as those in Examples 1-9 and Comparative Examples 1-2. Comparative Example 3 assembled a four-positive-five-negative solid-state pouch cell using the electrolyte membrane, ternary NCM811 positive electrode, and silicon-oxygen negative electrode of different sizes (positive electrode smaller than negative electrode) obtained in Comparative Example 1. Cycle stability was tested at 0.1C between 2.5-4.3V, and the test results are shown in Table 1 below.

[0072] Table 1

[0073]

[0074]

[0075] As shown in Table 1, the experimental results demonstrate that applying the anti-short-circuit electrolyte membrane to multilayer solid-state pouch batteries, under the same electrode and test conditions, can improve the first-cycle efficiency and capacity retention after 100 cycles, significantly reducing the occurrence of short circuits or overcharges. When cells or electrode assemblies containing the anti-short-circuit electrolyte membrane are assembled and subjected to pressure testing, the initial voltage is significantly higher than that of batteries without additional treatment. This proves that the anti-short-circuit electrolyte membrane can effectively separate the positive and negative electrode active material layers under applied pressure, preventing edge contact and further improving the success rate of solid-state battery prototypes.

[0076] By comparing the initial voltage and short-circuit data after pressurization of Example 1 and Comparative Example 1, it can be seen that under the same conditions, the electrolyte membrane with added inert insulating frame has a better effect in preventing short circuits. The initial voltage is higher, and it is more stable during cycling, avoiding direct short circuits or overcharging. By comparing the initial voltage and short-circuit data after pressurization of Example 1, Comparative Example 1, and Comparative Example 3, it can be seen that without inert insulating frame, regardless of whether the electrode size is consistent, there is a high short-circuit rate, and overcharging and short circuits are inevitable. Adding inert insulating frame can fully separate the positive and negative electrode active material layers, and the electrodes can be assembled with the same size, which greatly reduces the difficulty of operation. By comparing the initial voltage and short-circuit data after pressurization of Example 9 and Comparative Example 2, it can be seen that the electrolyte membrane with added inert insulating frame is also suitable for cases where the electrode size is larger.

[0077] The above embodiments are merely illustrative of the technical solutions of this utility model and are not intended to limit it. Although this utility model has been described in detail with reference to the foregoing embodiments, those skilled in the art should understand that modifications can be made to the technical solutions described in the foregoing embodiments, or equivalent substitutions can be made to some or all of the technical features therein, without departing from the spirit and substance defined by the claims of this utility model; and such modifications or substitutions are still within the scope defined by the claims of this utility model.

Claims

1. A solid-state battery designed to prevent short circuits, characterized in that, Comprise: A short-circuit prevention solid-state electrolyte film and an alternating stack of a positive electrode and a negative electrode, the short-circuit prevention solid-state electrolyte film being interposed between the positive electrode and the negative electrode; The short-circuit prevention solid-state electrolyte film comprises a solid-state electrolyte central region and an inert insulating frame on the periphery of the solid-state electrolyte central region; the inert insulating frame is an insulating elastic polyurethane frame; The short-circuit prevention solid-state electrolyte film, the positive electrode and the negative electrode are consistent in size; The thickness a of the solid-state electrolyte central region and the thickness b of the inert insulating frame satisfy: 0≤b-a≤30μm; The width L1 of the inert insulating frame in the length direction is: 1mm≤L1≤15mm, and the width L2 of the inert insulating frame in the width direction is: 1mm≤L2≤15mm.

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