CN112421100A

CN112421100A - Preparation method and application of glued solid electrolyte membrane

Info

Publication number: CN112421100A
Application number: CN201910774299.9A
Authority: CN
Inventors: 杨凡; 周翔; 晁流
Original assignee: Nanjing Bochi New Energy Co ltd
Current assignee: Nanjing Bochi New Energy Co ltd
Priority date: 2019-08-21
Filing date: 2019-08-21
Publication date: 2021-02-26

Abstract

The invention provides a preparation method and application of a gummed solid electrolyte membrane, and particularly relates to a method for coating a layer of glue layer on the surface of a solid electrolyte membrane, wherein the material of the gummed layer can conduct lithium ions when a battery is charged and discharged, and then the gummed solid electrolyte membrane is wound (or laminated) with a positive plate and a negative plate of the battery to form a bare cell and then is subjected to hot-pressing adhesion. The invention effectively improves the ionic conductivity between the solid electrolyte membrane of the solid lithium ion battery and the anode and cathode plates, and the internal resistance and the cycle performance of the solid lithium ion battery manufactured by the coating solid electrolyte membrane and the application process method thereof are obviously improved.

Description

Preparation method and application of glued solid electrolyte membrane

Technical Field

The invention relates to the technical field of solid lithium ion batteries, in particular to a preparation method and application of a gummed solid electrolyte membrane.

Background

The development of pure electric vehicles is always restricted by low energy density of batteries. The energy density of the battery is not greatly broken through, and the endurance mileage of the pure electric vehicle cannot be greatly improved. At present, the single energy density of the ternary lithium battery is close to the limit, and the specific gravity of nickel in the battery needs to be further improved in order to further improve the energy density of the ternary lithium battery. However, when the specific gravity of nickel in the battery is increased, the thermal stability of high nickel is poor, so that the thermal reaction inside the battery is very severe, and thus safety problems are worried. By means of a ternary lithium battery technical route, the energy density of the power battery is required to reach the target of 350Wh/kg, and the difficulty is high. Because the solid-state battery has no liquid electrolyte, is nonflammable, non-corrosive, nonvolatile, has good performance at high temperature and higher safety, the technical problem of further improving the energy density and the safety performance of the battery by the solid-state battery is urgently needed to be solved in the field. However, the solid-state battery has technical challenges in terms of battery internal resistance and cycle life because the internal resistance of the interface contact between the electrolyte of the solid-state battery and the positive and negative electrode sheets is large.

Disclosure of Invention

In order to overcome the technical problems, the invention provides a preparation method of a gummed solid electrolyte membrane, and the electrolyte membrane obtained by the method has the advantages of more compact solid-solid contact between a glue layer and a base membrane layer, higher ionic conductivity and more excellent performance in batteries.

The technical scheme of the invention is as follows:

a preparation method of a gummed solid electrolyte membrane comprises the following steps:

s1, dissolving the colloid main material in a required solvent, and mixing to obtain uniform gluing slurry;

and S2, coating the gluing slurry on the upper surface and the lower surface of the solid electrolyte membrane, and drying to obtain the gluing solid electrolyte membrane.

Preferably, the colloidal main material of the gummed slurry in S1 is one or more of polyvinylidene fluoride, polypropylene, polymethyl methacrylate and polyethylene oxide polymer.

Preferably, the solvent required by the sizing slurry in S1 is one or more of dimethylformamide, dimethyl sulfoxide, dichloromethane, N-methylpyrrolidone and deionized water.

Preferably, the mass ratio of the colloid main material to the solvent is 5-10: 100.

Preferably, a dispersing agent is also added into the S1, the dispersing agent is one or two of polyvinylpyrrolidone and sodium carboxymethyl cellulose, and the dispersing agent accounts for 0.5% of the weight of the main colloid material.

Preferably, the solid electrolyte membrane used in S2 is any one of a polymer, oxide, sulfide solid electrolyte membrane.

Preferably, in S2, a tape casting type, spraying type or gravure type coating device is adopted to carry out double-sided coating on the solid electrolyte membrane, and the thickness of a single coating layer is 0.2-10 μm; the drying temperature is 35-70 ℃.

The invention also provides application of the battery cell prepared by the method, and specifically the method further comprises the following steps:

and S3, winding or laminating the coated solid electrolyte membrane, the positive electrode plate and the negative electrode plate together to form a naked battery cell, and then carrying out hot-press bonding on the naked battery cell to obtain a final battery cell finished product.

Preferably, the hot-pressing bonding mode in S3 is air cylinder pressing plate type hot-pressing bonding, the pressure is 0.2-1.0 MPa, the pressing plate temperature is 60-110 ℃, and the hot-pressing pressure is maintained for 20-100S.

The material of the glue coating layer can conduct lithium ions when the battery is charged and discharged, and can effectively conduct the lithium ions between the solid electrolyte membrane and the anode and cathode pole pieces. The solid electrolyte membrane coated with the glue layer can be tightly adhered to the positive pole piece and the negative pole piece under the high-temperature hot-pressing condition, so that the ionic conductivity between the solid electrolyte membrane and the positive pole piece and the negative pole piece is greatly improved, and further, the cycle performance of the solid lithium ion battery is improved.

Description of the drawings:

FIG. 1 is a schematic view of a rubberized solid electrolyte membrane according to the invention;

fig. 2 is a schematic view of the hot-press bonding of bare cells according to the present invention;

FIG. 3 is a graph of a battery capacity cycling test according to an embodiment of the present invention;

in the figure, 1-solid electrolyte membrane, 2-glue coating layer, 3-naked electric core, 4-upper hot pressing plate, 5-lower hot pressing plate and 6-pressure cylinder.

The specific implementation mode is as follows:

example 1

dissolving polymethyl methacrylate and polyethylene oxide colloid main materials in a mass ratio of 1:2 into a mixed solvent of dichloromethane and dimethylformamide in a mass ratio of 1:1, and performing mixed stirring for 60-300 min by using a 50L volume planetary stirrer to perform revolution at 30rpm and disperse at 1200 rpm.

And adding 0.5 mass percent (relative to the main colloid material) of polyvinylpyrrolidone dispersing agent into the mixed slurry, and performing revolution at 30rpm and dispersion at 1200rpm for mixing and stirring for 30-90 min to obtain the low-viscosity (viscosity is 50-500cp) non-Newtonian fluid gluing slurry.

Coating the gluing slurry on the surfaces (upper surface and lower surface) of the solid electrolyte membrane by using a gravure coater, and drying by using a drying channel oven at 35-70 ℃ to obtain the glued solid electrolyte membrane, as shown in figure 1.

And winding the coated solid electrolyte membrane, a positive pole piece and a negative pole piece (the positive pole is LNCM523, and the negative pole is artificial graphite) into a naked battery cell (the theoretical design capacity of the battery cell is 6.5Ah) according to the lamination sequence of the coated solid electrolyte membrane, the positive pole piece, the coated solid electrolyte membrane and the negative pole piece.

Placing the bare cell in a hot-pressing board clamping groove of a hot-pressing device, and carrying out hot-pressing adhesion by using parameters of 85 ℃, 0.8MPa and 40s to obtain a tightly and hard wound cell in which the adhesive-coated solid electrolyte membrane is adhered to the positive and negative pole pieces, as shown in figure 2.

And (3) finishing the manufacture of a battery finished product (the battery is finally charged to 3.850V by using a 0.5C constant current and a constant voltage) by the steps of tab welding, external packaging treatment, high-temperature baking, pre-packaging, standing, formation, degassing, packaging, aging and capacity grading test.

The OCV, ACR, capacity of the battery in the above embodiment 1 were measured, see table 1.

3 normal cells from example 1 were selected for 0.5C/0.5C capacity cycling tests, see FIG. 3.

Comparative example 1

The conventional (non-coated) solid electrolyte membrane was used to prepare the cell, with the following steps:

the solid electrolyte membrane without glue coating and positive and negative pole pieces (the positive pole is LNCM523, the negative pole is artificial graphite) are wound into a naked cell (the theoretical design capacity of the cell is 6.5Ah) according to the lamination sequence of the solid electrolyte membrane, the positive pole piece, the solid electrolyte membrane and the negative pole piece.

Placing the naked electric core in a hot pressing plate clamping groove of hot pressing equipment, performing hot pressing adhesion by using parameters of 85 ℃, 0.8MPa and 40s, wherein the electric core after hot pressing is basically unchanged from the electric core before hot pressing.

The OCV, ACR, capacity of the cell of comparative example 1 above was tested and is shown in table 1.

3 normal cells of comparative example 1 above were selected for 0.5C/0.5C capacity cycling tests, see FIG. 3.

Table 1: example 1 and example 2 cell OCV, ACR/capacity test data.

The above embodiment is one of the embodiments implemented in the scope of the present invention, and any other hot press bonding processes (including but not limited to) using the gummed slurry made of various materials with other compounding ratios derived from the various materials described in the scope of the present invention, and other process parameters derived from the hot press bonding process method described in the present invention belong to the scope of the present invention.

Claims

1. The preparation method of the gummed solid electrolyte membrane is characterized by comprising the following steps:

2. The method according to claim 1, wherein the colloidal host material of the gummed slurry in S1 is one or more of polyvinylidene fluoride, polypropylene, polymethyl methacrylate and polyethylene oxide polymer.

3. The preparation method according to claim 1, wherein the solvent required by the sizing slurry in S1 is one or more of dimethylformamide, dimethyl sulfoxide, dichloromethane, N-methylpyrrolidone and deionized water.

4. The preparation method according to claim 1, wherein the mass ratio of the colloid main material to the solvent is 5-10: 100.

5. The preparation method according to claim 1, wherein a dispersant is further added to S1, the dispersant is one or both of polyvinylpyrrolidone and sodium carboxymethylcellulose, and the dispersant accounts for 0.5% of the weight of the colloidal main material.

6. The production method according to claim 1, wherein the solid electrolyte membrane used in S2 is any one of a polymer, an oxide, and a sulfide solid electrolyte membrane.

7. The preparation method according to claim 1, wherein in S2, a casting type, spraying type or gravure type coating device is used for double-sided coating of the solid electrolyte membrane, and the thickness of a single coating layer is 0.2-10 μm; the drying temperature is 35-70 ℃.

8. Use of a solid electrolyte membrane prepared according to any of claims 1 to 7 in the preparation of a cell.

9. The use according to claim 8, further comprising the steps of:

10. The use according to claim 9, wherein the thermocompression bonding in S3 is a cylinder platen thermocompression bonding, the pressure is 0.2-1.0 MPa, the platen temperature is 60-110 ℃, and the thermocompression pressure is maintained for 20-100S.