CN110311167A - A kind of composite solid electrolyte sheet and its preparation method and solid-state battery - Google Patents

Abstract

The present invention provides a kind of composite solid electrolyte pieces, comprising: the poly-dopamine layer on the electrolyte sheet surface is arranged in electrolyte sheet.Poly-dopamine layer in composite solid electrolyte piece provided by the invention is evenly distributed, can deformation occurs, solid electrolyte surface and positive electrode surface in solid state battery can be made to realize good interface contact, the influence that the volume change that electrode material occurs in cyclic process contacts electrode/electrolyte interface can be effectively reduced, reduce interface impedance, to promote the cycle performance and service life of battery.The present invention also provides the preparation methods and solid state battery of a kind of composite solid electrolyte piece.

Description

A kind of composite solid electrolyte sheet and its preparation method and solid-state battery

technical field

The invention relates to the technical field of batteries, in particular to a composite solid electrolyte sheet, a preparation method thereof, and a solid-state battery.

Background technique

In order to alleviate the current situation of environmental degradation and change the existing irrational energy structure, the development and storage of new green and clean energy has become an urgent task. In order to realize the utilization of green and clean energy, the research on electrochemical energy storage technology with less geographical restrictions and mature technology is very important. Therefore, it is of great significance to develop secondary batteries with high efficiency, safety, large capacity, long service life, and stable energy release during use.

Due to a series of advantages such as high energy density and long service life, lithium-ion batteries are widely used in 3C products, and have good application prospects in power batteries and smart grid energy storage. However, the electrolyte used in lithium-ion batteries is extremely prone to combustion and explosion, which affects the large-scale application of lithium-ion batteries. Therefore, improving its safety has become a key research direction. The all-solid-state battery using a safe and stable solid electrolyte solves the safety problem of the battery and effectively improves the energy density of the battery, so it is an important direction for future battery development.

However, due to the contact between the solid electrolyte and the electrode material in the form of a solid/solid interface, which is a point-to-point contact, the contact area is much smaller than the contact between the electrolyte and the electrode material, which hinders the transport of carriers at the interface, so the all-solid state The battery still has the problem of excessive interface resistance. In addition, during the charge-discharge cycle, the electrode material undergoes a volume change, resulting in a further reduction in the contact area between the solid electrolyte and the electrode material. The above factors will lead to a gradual decrease in the capacity of the all-solid-state battery during the charge-discharge cycle, and poor rate performance, which directly affects the energy density and power density of the battery. Therefore, how to solve the above-mentioned problems of solid-state batteries has become a research hotspot in this field.

Contents of the invention

In view of this, the object of the present invention is to provide a composite solid electrolyte, a preparation method thereof and a solid-state battery. The solid-state battery prepared by the composite electrolyte provided by the present invention has better cycle performance.

The invention provides a composite solid electrolyte sheet, comprising:

Electrolyte sheet;

A polydopamine layer arranged on the surface of the electrolyte layer.

In the present invention, the material of the electrolyte sheet can be selected from one of NASICON structure solid electrolyte, Garnet structure solid electrolyte and perovskite structure solid electrolyte.

In the present invention, the thickness of the electrolyte sheet may be 0.1-1 mm, or 0.2-0.8 mm, or 0.3-0.6 mm.

In the present invention, the polydopamine layer is mainly composed of polydopamine. In the present invention, the thickness of the polydopamine layer may be 2-500 nm, or 10-400 nm, or 50-300 nm, or 100-250 nm, or 150-200 nm.

In the present invention, the polydopamine layer is arranged on one side surface of the electrolyte sheet.

The present invention provides a method for preparing the composite solid electrolyte sheet described in the above technical solution, comprising:

mixing dopamine hydrochloride, additives and solvents to obtain a dopamine polymerization solution;

The dopamine polymerization solution and the electrolyte sheet are mixed and then dried to obtain a composite solid electrolyte sheet.

In the present invention, the auxiliary agent may be selected from trihydroxymethylaminomethane, cetyltrimethylammonium bromide or polyvinyl alcohol.

In the present invention, the solvent may be selected from water, ethanol or isopropanol.

In the present invention, the mass ratio of dopamine hydrochloride, additives and solvents can be (1-30): (0.05-1): 100, or (5-25): (0.1-0.8): 100, It may also be (10-20):(0.3-0.7):100.

In the present invention, the mixing method can be:

Mix the additive and the solvent to obtain a mixed solution;

Dopamine hydrochloride is added into the mixed solution to obtain a dopamine polymerization solution.

In the present invention, the method of mixing the dopamine polymerization solution and the electrolyte sheet can be:

The electrolyte sheet was soaked in the dopamine polymerization solution.

In the present invention, before mixing the electrolyte sheet and the dopamine polymerization solution, it may also include:

Polish and clean the surface of the electrolyte sheet.

In the present invention, the cleaning reagent may be ethanol.

In the present invention, the mixing temperature of the electrolyte sheet and the dopamine polymerization solution may be 40-80°C, or 50-70°C, or 60°C; the mixing time of the electrolyte sheet and the dopamine polymerization solution may be 10-15 hours, or 12-13 hours; to complete the growth of the polydopamine layer on the surface of the electrolyte sheet.

In the present invention, before said drying may also include:

The electrolyte sheet mixed with the dopamine polymerization solution was rinsed with water.

In the present invention, the water may be distilled water.

In the present invention, the drying may be performed in an oven. In the present invention, the drying temperature may be 70-90°C, or 75-85°C, or 80°C; the drying time may be 10-15 hours, or 12-13 hours .

The invention provides a solid-state battery, comprising: a negative electrode material, a composite solid electrolyte sheet and a composite positive electrode material.

In the present invention, the material of the negative electrode material can be selected from metal lithium, metal sodium or alloy; the alloy can be selected from lithium indium alloy or lithium tin alloy.

In the present invention, the shape of the negative electrode material may be a sheet; the thickness of the sheet-shaped negative electrode material may be 0.1-3 mm, or 0.5-2.5 mm, or 1-2 mm.

In the present invention, the composite solid electrolyte sheet is consistent with the composite solid electrolyte sheet described in the above technical solution, and will not be repeated here.

In the present invention, the composite positive electrode may include:

Cathode material, solid electrolyte powder, conductive additive and binder.

In the present invention, the positive electrode material may be selected from FeS ₂ , Fe _1-x S, WS ₂ , Na ₃ V ₂ (PO ₄ ) ₃ , LiCoO ₂ , LiFePO ₄ , NCM or NCA.

In the present invention, the material of the solid electrolyte powder can be selected from one or more of NASICON-structured solid electrolytes, Garnet-structured solid electrolytes and perovskite-structured solid electrolytes.

In the present invention, the particle size of the solid electrolyte powder may be 0.1-10 μm, or 0.5-8 μm, or 2-6 μm.

In the present invention, the conductive additive may be selected from one or more of Ketjen black, acetylene black, Super P, carbon nanotubes and graphene.

In the present invention, the binder can be selected from one of ethyl cellulose (EC), polyvinylidene fluoride (PVDF), sodium alginate (SA) and sodium carboxymethyl cellulose (CMC) or Several kinds.

In the present invention, the mass ratio of the positive electrode material, solid electrolyte powder, conductive additive and binder may be (45-70): (15-40): (10-20): (5-15), or It can be (50-65): (20-35): (12-18): (8-12), or (55-60): (25-30): (14-16): 15.

In the present invention, the shape of the composite positive electrode may be layered, and the thickness of the layered composite positive electrode material may be 0.1-500 μm, or 0.5-400 μm, or 1-300 μm, or 10-200 μm, It may be 50-150 micrometers, and may be 100 micrometers.

In the present invention, the preparation method of the composite positive electrode can be:

Mix positive electrode material, solid electrolyte powder, conductive additive, binder and solvent to obtain positive electrode slurry;

The positive electrode slurry is coated on the surface of the composite solid electrolyte sheet with the polydopamine layer and then dried to obtain a composite positive electrode.

In the present invention, the type and amount of the positive electrode material, solid electrolyte powder, conductive additive and binder are consistent with the type and amount of positive electrode material, solid electrolyte powder, conductive additive and binder described in the above technical solution. This will not be repeated here.

In the present invention, the solvent may be selected from one or both of N-methylpyrrolidone and terpineol. In the present invention, there is no special limitation on the amount of the solvent used, as long as the solvent can dissolve the components in the positive electrode material.

In the present invention, the thickness of the coating is consistent with the thickness of the layered composite positive electrode described in the above technical solution, and will not be repeated here.

In the present invention, the drying temperature may be 70-90°C, or 75-85°C, or 80°C; the drying time may be 10-15 hours, or 12-13 hours .

In the present invention, the solid-state battery may include:

Composite solid electrolyte sheet;

A composite positive electrode provided on the surface of the composite solid electrolyte sheet with a layer of polydopamine;

The negative electrode material arranged on the surface of the other side of the composite solid electrolyte sheet.

In the present invention, the preparation method of the solid-state battery can be:

Loading the composite positive electrode on the surface of the composite solid electrolyte sheet with a polydopamine layer;

The negative electrode material is loaded on the surface of the other side of the composite solid electrolyte sheet, assembled into a battery and sealed to obtain a solid state battery.

In the present invention, the method of loading the composite positive electrode on the surface of the composite solid electrolyte sheet with the polydopamine layer is consistent with the preparation method of the composite positive electrode described in the above technical solution, and will not be repeated here.

In the present invention, the loading of the negative electrode material can be carried out under an inert atmosphere, more preferably in an inert atmosphere glove box.

The present invention optimizes the interface between the solid electrolyte and the electrode material, by setting a layer of uniformly distributed, fully contacted, and deformable high molecular polymer polydopamine modification layer on the surface of the solid electrolyte to improve the contact between the solid electrolyte and the electrode material Purpose. Studies have shown that the addition of the polydopamine modification layer in the present invention can significantly improve the cycle performance of the solid-state battery, prolong the service life of the battery, and effectively expand the application of the solid-state battery in the fields of energy and environmental protection.

The solid-state battery provided by the present invention has a polydopamine polymer modification layer, which has a large surface area, can fully contact the surface of the solid electrolyte and the surface of the positive electrode in the solid-state battery, and can further reduce the volume of the positive electrode during charging and discharging through deformation The impact of changes on the electrode/electrolyte interface contact, thereby improving the battery interface contact, reducing the interface impedance, and improving the cycle performance and service life of the battery. After the polydopamine polymer modification layer is adopted in the present invention, the cycle stability and service life of the assembled solid-state battery are obviously improved. In addition, the preparation method provided by the invention is simple and efficient, and is suitable for large-scale application.

Description of drawings

In order to more clearly illustrate the embodiments of the present invention or the technical solutions in the prior art, the following will briefly introduce the drawings that need to be used in the description of the embodiments or the prior art. Obviously, the accompanying drawings in the following description are only It is an embodiment of the present invention, and those skilled in the art can also obtain other drawings according to the provided drawings on the premise of not paying creative efforts.

Fig. 1 is the SEM image of the surface morphology of the polydopamine polymer modification layer prepared in Example 1 of the present invention;

2 is a cycle performance curve and a Coulombic efficiency curve of the solid-state battery in Example 1 of the present invention at a current density of 0.1C;

3 is a cycle performance curve and a Coulombic efficiency curve of the solid-state battery in Example 2 of the present invention at a current density of 0.1C;

Fig. 4 is a cycle performance curve and a coulombic efficiency curve of the solid-state battery in Example 3 of the present invention at a current density of 0.1C;

5 is a cycle performance curve and a Coulombic efficiency curve of the solid-state battery in Example 4 of the present invention at a current density of 0.1C;

Fig. 6 is a cycle performance curve and a coulombic efficiency curve of the solid-state battery in Example 5 of the present invention at a current density of 0.1C;

Fig. 7 is a cycle performance curve and a Coulombic efficiency curve of the solid-state battery in Example 6 of the present invention at a current density of 0.1C;

Fig. 8 is a cycle performance curve and a Coulombic efficiency curve of the solid-state battery in Example 7 of the present invention at a current density of 0.1C;

Fig. 9 is a cycle performance curve and a coulombic efficiency curve of the solid-state battery in Example 8 of the present invention at a current density of 0.1C;

Fig. 10 is a cycle performance curve and a Coulombic efficiency curve of the solid-state battery in Comparative Example 1 of the present invention at a current density of 0.1C;

Figure 11 is a cycle performance curve and a Coulombic efficiency curve of the solid-state battery in Comparative Example 2 of the present invention at a current density of 0.1C;

Fig. 12 is a cycle performance curve and a Coulombic efficiency curve of the solid-state battery in Comparative Example 3 of the present invention at a current density of 0.1C.

Detailed ways

The following will clearly and completely describe the technical solutions in the embodiments of the present invention with reference to the accompanying drawings in the embodiments of the present invention. Obviously, the described embodiments are only some, not all, embodiments of the present invention. Based on the embodiments of the present invention, all other embodiments obtained by persons of ordinary skill in the art without making creative efforts belong to the protection scope of the present invention.

The raw materials used in the following examples of the present invention are all commercially available products, the electrolyte sheet used is provided by Hefei Kejing Material Technology Co., Ltd., the dopamine hydrochloride used is provided by Aladdin Company, and the positive electrode material used is Hunan Binbin New Material Co., Ltd. The solid electrolyte powder is provided by Hefei Kejing Material Technology Co., Ltd., the conductive agent is provided by Nanjing Xianfeng Nano Material Technology Co., Ltd., and the negative electrode material is provided by Sigma Aldrich Company and Tianjin Zhongneng Lithium Industry Co., Ltd. of.

Example 1

Polish the surface of NASICON solid electrolyte sheets with a thickness of 0.6mm, wash them in ethanol and dry them for later use. Dissolve trishydroxymethylaminomethane in ethanol and stir for 2 hours until uniform to obtain a solution with a concentration of 0.1mol/L. Then add 20 mg of dopamine hydrochloride to 100 ml of the above solution, stir evenly, put the solid electrolyte sheet into it, and keep stirring at 50° C. for 12 hours to complete the growth of the polymer-modified layer on the surface of the solid electrolyte sheet. Then the electrolyte sheet with the polymer modification layer was taken out, washed with distilled water, put into a drying oven, and dried at 80° C. for 12 hours to complete the preparation of the polydopamine modification layer and obtain a composite solid electrolyte sheet.

Mix positive electrode material FeS ₂ , NASICON solid electrolyte powder, conductive agent Super P, and binder EC at a mass ratio of 50:25:15:10, add terpineol as a solvent, and mix to make positive electrode slurry. The above positive electrode slurry was uniformly coated on the surface of the composite solid electrolyte sheet with the polydopamine layer, and dried at 80° C. for 12 hours. The above-mentioned composite solid electrolyte sheet coated with positive electrode material was transferred into an inert atmosphere glove box, and a metal Na sheet with a thickness of 0.5 mm was loaded on the other side of the composite solid electrolyte sheet, assembled into a battery and sealed to obtain a solid-state battery.

SEM detection was carried out on the polydopamine layer of the composite solid electrolyte sheet prepared in Example 1 of the present invention, and the detection results are shown in Figure 1. It can be seen from Figure 1 that the polydopamine polymer modification layer grows uniformly on the crystal grains on the surface of the electrolyte sheet.

The solid-state battery prepared in Example 1 of the present invention was tested for its electrochemical performance using the Blue Electric CT2001A battery test system. The charging and discharging voltage range was 0.8-3.0V, the temperature was 60°C, and the current density was 0.1C, and then it was charged at a constant rate. Discharge, evaluate the discharge capacity retention rate and coulombic efficiency of 50 cycles, and the test results are shown in Figure 2. As can be seen from Figure 2, the solid-state battery prepared by this solid electrolyte sheet with a polydopamine-modified layer is 60 The first discharge specific capacity at ℃ and 0.1C current density is 460.3mAh/g, and the first charge specific capacity is 251.9mAh/g. After 50 cycles of charging and discharging, the discharge specific capacity is 149.0mAh/g, the charge specific capacity is 148.7mAh/g, and the Coulombic efficiency is 99.83%. After stable cycling, the battery capacity retention rate is high.

Example 2

Polish the surface of NASICON solid electrolyte sheets with a thickness of 0.4mm, wash them in ethanol and dry them for later use. Dissolve hexadecyltrimethylammonium bromide in distilled water and stir for 2 hours until uniform to obtain a solution with a concentration of 0.05 mol/L. Add 10 mg of dopamine hydrochloride to 100 ml of the above solution, stir evenly, put the solid electrolyte sheet into it, and keep stirring at 60° C. for 10 h to complete the growth of the polymer-modified layer on the surface of the solid electrolyte sheet. Then the solid electrolyte sheet with the polymer modification layer was taken out, washed with distilled water, put into a drying oven, and dried at 80° C. for 12 hours to complete the preparation of the polydopamine modification layer to obtain a composite solid electrolyte sheet.

Mix positive electrode material FeS ₂ , NASICON solid electrolyte powder, conductive agent acetylene black, and binder PVDF at a mass ratio of 50:30:15:5, add NMP as a solvent, and mix to make positive electrode slurry. The positive electrode slurry was uniformly coated on the surface of the composite solid electrolyte sheet with the polydopamine layer, the coating thickness was 0.2 mm, and dried at 80° C. for 12 hours. The above-mentioned composite solid electrolyte sheet coated with positive electrode slurry was transferred into an inert atmosphere glove box, and a metal Na sheet with a thickness of 0.4 mm was loaded on the other side of the composite solid electrolyte sheet, assembled into a battery and sealed to obtain a solid-state battery.

The electrochemical performance of the solid-state battery prepared in Example 2 of the present invention was tested using the Blue Electric CT2001A battery test system. The charging and discharging voltage range was 0.8-3.0V, the temperature was 60°C, and the current density was 0.1C, and then a constant rate charge was carried out. Discharge, evaluate the discharge capacity retention rate and coulombic efficiency of 50 cycles, and the test results are shown in Figure 3. As can be seen from Figure 3, the solid-state battery prepared by this solid electrolyte sheet with a polymer-modified layer is 60 The first discharge specific capacity at ℃ and 0.1C current density is 320.5mAh/g, and the first charge specific capacity is 182.0mAh/g. After 50 cycles of charging and discharging, the discharge specific capacity is 163.0mAh/g, the charge specific capacity is 162.1mAh/g, and the Coulombic efficiency is 99.44%. After stable cycling, the battery capacity retention rate is high.

Example 3

Polish the surface of NASICON solid electrolyte sheets with a thickness of 0.8mm, wash them in ethanol and dry them for later use. Dissolve trishydroxymethylaminomethane in isopropanol and stir for 2 hours until uniform to obtain a solution with a concentration of 0.2 mol/L. Then add 20 mg of dopamine hydrochloride to 100 ml of the above solution, stir evenly, put the solid electrolyte sheet into it, and keep stirring at 70° C. for 6 hours to complete the growth of the polymer-modified layer on the surface of the solid electrolyte sheet. Then the solid electrolyte sheet with the polymer modification layer was taken out, washed with distilled water, put into a drying oven, and dried at 80° C. for 12 hours to complete the preparation of the polydopamine modification layer to obtain a composite solid electrolyte sheet.

Mix the positive electrode material Fe _1-x S, NASICON solid electrolyte powder, conductive agent Super P, and binder CMC at a mass ratio of 50:20:20:10, add NMP as a solvent, and mix to form a positive electrode slurry. The positive electrode slurry was uniformly coated on the surface of the composite solid electrolyte sheet with the polydopamine layer, the coating thickness was 0.15 mm, and dried at 80° C. for 12 hours. The above-mentioned composite solid electrolyte sheet coated with positive electrode slurry was transferred into an inert atmosphere glove box, and a metal Na sheet with a thickness of 0.5 mm was loaded on the other side of the composite solid electrolyte sheet, assembled into a battery and sealed to obtain a solid-state battery.

The solid-state battery prepared in Example 3 of the present invention was tested for electrochemical performance using the Blue Electric CT2001A battery test system. The charging and discharging voltage range was 0.5-3.0V, the temperature was 60°C, and the current density was 0.1C, and then the constant rate charge was carried out. Discharge, evaluate the discharge capacity retention rate and coulombic efficiency of 50 cycles, the test results are shown in Figure 4, as can be seen from Figure 4, the solid-state battery prepared by this solid electrolyte sheet with a polymer modification layer has The first discharge specific capacity at ℃ and 0.1C current density is 518.3mAh/g, and the first charge specific capacity is 320.0mAh/g. After 50 cycles of charging and discharging, the discharge specific capacity is 215.0mAh/g, the charge specific capacity is 214.2mAh/g, and the Coulombic efficiency is 99.61%. After stable cycling, the battery capacity retention rate is high.

Example 4

Polish the surface of NASICON solid electrolyte sheets with a thickness of 0.5mm, wash them in ethanol and dry them for later use. Dissolve polyvinyl alcohol in distilled water and stir for 2 hours until uniform to obtain a solution with a concentration of 0.2 mol/L. Add 20 mg of dopamine hydrochloride to 100 ml of the above solution, stir evenly, put the solid electrolyte sheet into it, and keep stirring at 80° C. for 10 h to complete the growth of the polymer-modified layer on the surface of the solid electrolyte sheet. Then the solid electrolyte sheet with the polymer modification layer was taken out, washed with distilled water, put into a drying oven, and dried at 80° C. for 12 hours to complete the preparation of the polydopamine modification layer and obtain a composite solid electrolyte sheet.

Mix positive electrode material FeS ₂ , NASICON solid electrolyte powder, conductive agent graphene, and binder SA at a mass ratio of 55:20:15:10, add terpineol as a solvent, and mix to make positive electrode slurry. The above positive electrode slurry was evenly coated on the surface of the composite solid electrolyte sheet with the polydopamine layer, the coating thickness was 0.3 mm, and dried at 80° C. for 12 hours. The above-mentioned composite solid electrolyte sheet coated with positive electrode slurry was transferred into an inert atmosphere glove box, and a metal Na sheet with a thickness of 0.3 mm was loaded on the other side of the composite solid electrolyte sheet, assembled into a battery and sealed to obtain a solid-state battery.

The electrochemical performance of the solid-state battery prepared in Example 4 of the present invention was tested using the Blue Electric CT2001A battery test system. The charging and discharging voltage range was 0.8-3.0V, the temperature was 60°C, and the current density was 0.1C, and then a constant rate charge was carried out. Discharge, evaluate the discharge capacity retention rate and coulombic efficiency of 50 cycles, the test results are shown in Figure 5, as can be seen from Figure 5, the solid-state battery prepared by this solid electrolyte sheet with a polymer modified layer has a 60 The first discharge specific capacity at ℃ and 0.1C current density is 417.8mAh/g, and the first charge specific capacity is 267.6mAh/g. After 50 cycles of charging and discharging, the discharge specific capacity is 205.0mAh/g, the charge specific capacity is 203.2mAh/g, and the Coulombic efficiency is 99.11%. After stable cycling, the battery capacity retention rate is high.

Example 5

Polish the surface of Garnet solid electrolyte sheets with a thickness of 1mm, wash them in ethanol and dry them for later use. Dissolve trishydroxymethylaminomethane in distilled water and stir for 2 hours until uniform to obtain a solution with a concentration of 0.2 mol/L. Add 25 mg of dopamine hydrochloride to 100 ml of the above solution, stir evenly, put the solid electrolyte sheet into it, and keep stirring at 80° C. for 12 hours to complete the growth of the polymer-modified layer on the surface of the solid electrolyte sheet. Then the solid electrolyte sheet with the polymer modification layer was taken out, washed with distilled water, put into a drying oven, and dried at 80° C. for 12 hours to complete the preparation of the polydopamine modification layer to obtain a composite solid electrolyte sheet.

The positive electrode material LiFePO ₄ , Garnet solid electrolyte powder, conductive agent Super P, and binder EC were mixed in a mass ratio of 60:20:10:10, and terpineol was added as a solvent to make positive electrode slurry. The positive electrode slurry was uniformly coated on the surface of the composite solid electrolyte sheet with the polydopamine layer, the coating thickness was 0.1 mm, and dried at 80° C. for 12 hours. The above-mentioned composite solid electrolyte sheet coated with positive electrode material was transferred into an inert atmosphere glove box, and a metal Li sheet with a thickness of 0.2 mm was loaded on the other side of the composite solid electrolyte sheet, assembled into a battery and sealed to obtain a solid-state battery.

The solid-state battery prepared in Example 5 of the present invention was tested for electrochemical performance using the Blue Electric CT2001A battery test system. The charging and discharging voltage range was 2.8-3.8V, the temperature was 60°C, and the current density was 0.1C, and then a constant rate charge was carried out. Discharge, evaluate the discharge capacity retention rate and coulombic efficiency of 50 cycles, and the test results are shown in Figure 6. It can be seen from Figure 6 that the solid-state battery prepared by this solid electrolyte sheet with a polymer modification layer is ℃, 0.1C current density, the first charge specific capacity is 145.2mAh/g, and the first discharge specific capacity is 144.6mAh/g. After 50 cycles of charging and discharging, the charge specific capacity is 140.7mAh/g, the discharge specific capacity is 140.2mAh/g, and the Coulombic efficiency is 99.64%. After stable cycling, the battery capacity retention rate is high.

Example 6

Polish the surface of Garnet solid electrolyte sheets with a thickness of 1mm, wash them in ethanol and dry them for later use. Dissolve hexadecyltrimethylammonium bromide in isopropanol and stir for 2 hours until uniform to obtain a solution with a concentration of 0.1mol/L. Add 15 mg of dopamine hydrochloride to 100 ml of the above solution, stir evenly, put the solid electrolyte sheet into it, and keep stirring at 60° C. for 6 hours to complete the growth of the polymer-modified layer on the surface of the solid electrolyte sheet. Then the solid electrolyte sheet with the polymer modification layer was taken out, washed with distilled water, put into a drying oven, and dried at 80° C. for 12 hours to complete the preparation of the polydopamine modification layer to obtain a composite solid electrolyte sheet.

The positive electrode material LiCoO ₂ , Garnet solid electrolyte powder, carbon nanotubes, and binder PVDF were mixed according to a mass ratio of 70:15:10:5, and terpineol was added as a solvent to prepare the positive electrode slurry. The above-mentioned cathode slurry was evenly coated on the above-mentioned composite solid electrolyte sheet with a coating thickness of 0.3 mm, and dried at 80° C. for 12 hours. The above-mentioned composite solid electrolyte sheet coated with positive electrode slurry was transferred into an inert atmosphere glove box, and a Li-In alloy negative electrode with a thickness of 0.6 mm was loaded on the other side of the composite solid electrolyte sheet, assembled into a battery and sealed to obtain a solid-state battery.

The solid-state battery prepared in Example 6 of the present invention was tested for electrochemical performance using the Blue Electric CT2001A battery test system. The charging and discharging voltage range was 2.5 to 3.6V, the temperature was room temperature, and the current density was 0.1C. Then, constant rate charging and discharging was performed. , to evaluate the discharge capacity retention and coulombic efficiency of 50 cycles, and the test results are shown in Figure 7. It can be seen from Figure 7 that the solid-state battery prepared from this solid electrolyte sheet with a polymer modified layer can be cooled at 60 ° C , The first charge specific capacity at 0.1C current density is 81.6mAh/g, and the first discharge specific capacity is 72mAh/g. After 50 cycles of charging and discharging, the charge specific capacity is 95.9mAh/g, the discharge specific capacity is 95.6mAh/g, and the Coulombic efficiency is 99.69%. After stable cycling, the battery capacity retention rate is high.

Example 7

Polish the surface of Garnet solid electrolyte sheets with a thickness of 1mm, wash them in ethanol and dry them for later use. Dissolve trishydroxymethylaminomethane in isopropanol and stir for 2 hours until uniform to obtain a solution with a concentration of 0.3 mol/L. Then add 25 mg of dopamine hydrochloride to 100 ml of the above solution, stir evenly, put the solid electrolyte sheet into it, and keep stirring at 50° C. for 4 hours to complete the growth of the polymer modification layer on the surface of the solid electrolyte sheet. Then the solid electrolyte sheet with the polymer modification layer was taken out, washed with distilled water, put into a drying oven, and dried at 80° C. for 12 hours to complete the preparation of the polydopamine modification layer to obtain a composite solid electrolyte sheet.

The positive electrode material NCA, Garnet solid electrolyte powder, Ketjen black, and binder PVDF were mixed in a mass ratio of 65:20:10:5, NMP was added as a solvent, and mixed to form a positive electrode slurry. The positive electrode slurry was uniformly coated on the surface of the composite solid electrolyte sheet with the polydopamine layer, the coating thickness was 0.4 mm, and dried at 80° C. for 12 hours. The above-mentioned coated composite solid electrolyte sheet was transferred into an inert atmosphere glove box, and a Li-In alloy negative electrode with a thickness of 0.5 mm was loaded on the other side of the composite solid electrolyte sheet, assembled into a battery and sealed to obtain a solid-state battery.

The solid-state battery prepared in Example 7 of the present invention was tested for electrochemical performance using the Blue Electric CT2001A battery test system. The charging and discharging voltage range was 2.5 to 3.6V, the temperature was room temperature, and the current density was 0.1C, and then a constant rate charging and discharging was performed. , to evaluate the discharge capacity retention and coulombic efficiency of 50 cycles, and the test results are shown in Figure 8. It can be seen from Figure 8 that the solid-state battery prepared from this solid electrolyte sheet with a polymer modified layer can be cooled at 60 ° C , The first charge specific capacity at 0.1C current density is 104.4mAh/g, and the first discharge specific capacity is 81.6mAh/g. After 50 cycles of charging and discharging, the charge specific capacity is 71.6mAh/g, the discharge specific capacity is 70.7mAh/g, and the Coulombic efficiency is 98.74%. After stable cycling, the battery capacity retention rate is high.

Example 8

Polish the surface of NASICON solid electrolyte sheets with a thickness of 0.5mm, wash them in ethanol and dry them for later use. Dissolve polyvinyl alcohol in water and stir for 2 hours until uniform to obtain a solution with a concentration of 0.3 mol/L. Add 15 mg of dopamine hydrochloride to 100 ml of the above solution, stir evenly, put the solid electrolyte sheet into it, and keep stirring at 80° C. for 8 hours to complete the growth of the polymer-modified layer on the surface of the solid electrolyte sheet. Then the solid electrolyte sheet with the polymer modification layer was taken out, washed with distilled water, put into a drying oven, and dried at 80° C. for 12 hours to complete the preparation of the polydopamine modification layer to obtain a composite solid electrolyte sheet.

Mix the positive electrode material Na ₃ V ₂ (PO ₄ ) ₃ , NASICON solid electrolyte powder, acetylene black, and binder EC at a mass ratio of 55:25:10:10, add terpineol as a solvent, and mix to make a positive electrode slurry material. The positive electrode slurry was uniformly coated on the surface of the composite solid electrolyte sheet with the polydopamine layer, the coating thickness was 0.25 mm, and dried at 80° C. for 12 hours. The above-mentioned composite solid electrolyte sheet coated with positive electrode slurry was transferred into an inert atmosphere glove box, and a metal Na sheet with a thickness of 0.4 mm was loaded on the other side of the composite solid electrolyte sheet, assembled into a battery and sealed to obtain a solid-state battery.

The solid-state battery prepared in Example 8 of the present invention was tested for electrochemical performance using the Blue Electric CT2001A battery test system. The voltage range of charge and discharge was 2.5-4.0V, the temperature was room temperature, and the current density was 0.1C, and then charged and discharged at a constant rate , to evaluate the discharge capacity retention and coulombic efficiency of 50 cycles, and the test results are shown in Figure 9. It can be seen from Figure 9 that the solid-state battery prepared from this solid electrolyte sheet with a polymer-modified layer is stable at 60 ° C , The first charge specific capacity at 0.1C current density is 87.3mAh/g, and the first discharge specific capacity is 79.2mAh/g. After 50 cycles of charging and discharging, the charging specific capacity is 66.0mAh/g, the discharging specific capacity is 65.7mAh/g, and the Coulombic efficiency is 99.55%. After stable cycling, the battery capacity retention rate is high.

Comparative example 1

Polish the surface of NASICON solid electrolyte sheets with a thickness of 0.5mm, wash them in ethanol and dry them for later use. Mix positive electrode material FeS ₂ , NASICON solid electrolyte powder, conductive agent Super P, and binder CMC at a mass ratio of 50:25:20:5, add NMP as a solvent, and mix to make positive electrode slurry. The above positive electrode slurry was evenly coated on the above unmodified solid electrolyte sheet with a coating thickness of 0.2 mm, and dried at 80° C. for 12 hours. The electrolyte sheet coated with the positive electrode material was transferred into an inert atmosphere glove box, and a metal Na sheet with a thickness of 0.5 mm was loaded on the other side of the electrolyte sheet, assembled into a battery and sealed to obtain a solid-state battery.

The solid-state battery prepared in Comparative Example 1 of the present invention was tested for electrochemical performance using the Blue Electric CT2001A battery test system. The charging and discharging voltage range was 0.8 to 3.0V, the temperature was 60°C, and the current density was 0.1C, and then the battery was charged at a constant rate. Discharge, evaluate the discharge capacity retention rate and coulombic efficiency of 50 cycles, and the test results are shown in Figure 10. It can be seen from Figure 10 that the solid-state battery prepared by this solid electrolyte sheet without a polymer modification layer is 60 The first discharge specific capacity at ℃ and 0.1C current density is 453.3mAh/g, and the first charge specific capacity is 315.8mAh/g. After 50 cycles of charging and discharging, the discharge specific capacity is 99.1mAh/g, the charge specific capacity is 89.9mAh/g, and the Coulombic efficiency is 90.65%. The battery has obvious capacity decay during long-term cycling, poor cycle stability, and reduced Coulombic efficiency.

Comparative example 2

Polish the surface of NASICON solid electrolyte sheets with a thickness of 0.6mm, wash them in ethanol and dry them for later use. Mix positive electrode material FeS ₂ , NASICON solid electrolyte powder, conductive agent Ketjen black, and binder PVDF at a mass ratio of 45:20:25:10, add NMP as a solvent, and mix to make positive electrode slurry. The above positive electrode slurry was evenly coated on the above unmodified solid electrolyte sheet with a coating thickness of 0.15 mm, and dried at 80° C. for 12 hours. The above-mentioned electrolyte sheet coated with positive electrode slurry was transferred into an inert atmosphere glove box, and a metal Na sheet with a thickness of 0.5 mm was loaded on the other side of the electrolyte sheet, assembled into a battery and sealed to obtain a solid-state battery.

The solid-state battery prepared in Comparative Example 2 of the present invention was tested for electrochemical performance using the Blue Electric CT2001A battery test system. The charging and discharging voltage range was 0.8-3.0V, the temperature was 60°C, and the current density was 0.1C, and then the constant rate charge was carried out. Discharge, evaluate the discharge capacity retention rate and coulombic efficiency of 50 cycles, the test results are shown in Figure 11, as can be seen from Figure 11, the solid-state battery prepared by this solid electrolyte sheet without a polymer modification layer is 60 The first discharge specific capacity at ℃ and 0.1C current density is 390.0mAh/g, and the first charge specific capacity is 295.4mAh/g. After 50 cycles of charging and discharging, the discharge specific capacity is 55.8mAh/g, the charge specific capacity is 53.6mAh/g, and the Coulombic efficiency is 96.09%. The battery has obvious capacity decay during long-term cycling, poor cycle stability, and reduced Coulombic efficiency.

Comparative example 3

Polish the surface of the NASICON solid electrolyte sheet with a thickness of 0.7mm, wash and dry it in ethanol, and transfer it to an inert atmosphere glove box. Dissolve PEO in acetonitrile, mix conductive lithium salt LiTFSI with PEO according to the ratio of EO group: Li ⁺ =18:1 and stir evenly. The PEO solution was uniformly coated on the surface of the solid electrolyte sheet and dried to a thickness of 0.3 mm to complete the preparation of the PEO layer to obtain a composite solid electrolyte sheet. Mix positive electrode material FeS ₂ , NASICON solid electrolyte powder, conductive carbon nanotubes, and binder PVDF at a mass ratio of 65:15:15:5, add NMP as a solvent, and mix to make positive electrode slurry. The above positive electrode slurry was evenly coated on the above unmodified solid electrolyte sheet with a coating thickness of 0.25 mm, and dried at 80° C. for 12 hours. A metal Na sheet with a thickness of 0.5 mm is loaded on the other side of the electrolyte sheet coated with the positive electrode slurry, assembled into a battery and sealed to obtain a solid-state battery.

The solid-state battery prepared in Comparative Example 3 of the present invention was tested for electrochemical performance using the Blue Electric CT2001A battery testing system. The charging and discharging voltage range was 0.8-3.0V, the temperature was 60°C, and the current density was 0.1C, and then the battery was charged at a constant rate. Discharge, evaluate the discharge capacity retention rate and coulombic efficiency of 50 cycles, and the test results are shown in Figure 12. It can be seen from Figure 12 that the solid-state battery prepared by this solid electrolyte sheet without a polymer modification layer is The first discharge specific capacity at ℃ and 0.1C current density is 372.3mAh/g, and the first charge specific capacity is 355.4mAh/g. After 50 cycles of charging and discharging, the discharge specific capacity is 155.5mAh/g, the charge specific capacity is 154.2mAh/g, and the Coulombic efficiency is 99.17%. The battery has obvious capacity fading during long-term cycle.

The above description of the disclosed embodiments is provided to enable any person skilled in the art to make or use the invention. Various modifications to these embodiments will be readily apparent to those skilled in the art, and the general principles defined herein may be implemented in other embodiments without departing from the spirit or scope of the invention. Therefore, the present invention will not be limited to the embodiments shown herein, but is to be accorded the widest scope consistent with the principles and novel features disclosed herein.

Claims (10)

1. a kind of composite solid electrolyte piece, comprising:

Electrolyte sheet；

The poly-dopamine layer on the electrolyte sheet surface is set.

2. composite solid electrolyte piece according to claim 1, which is characterized in that the material of the electrolyte sheet is selected from One in the solid electrolyte of NASICON structure, the solid electrolyte of Garnet structure and the solid electrolyte of perovskite structure Kind is several.

3. composite solid electrolyte piece according to claim 1, which is characterized in that the poly-dopamine layer with a thickness of 2 ~500nm.

4. a kind of preparation method of composite solid electrolyte piece, comprising:

Dopamine hydrochloride, auxiliary agent and solvent are mixed, dopamine polymeric solution is obtained；

It is dry after the dopamine polymeric solution and electrolyte sheet are mixed, obtain composite solid electrolyte piece.

5. according to the method described in claim 4, it is characterized in that, the auxiliary agent is selected from trishydroxymethylaminomethane, 16 Alkyl trimethyl ammonium bromide or polyvinyl alcohol.

6. according to the method described in claim 4, it is characterized in that, the solvent is selected from water, ethyl alcohol or isopropanol.

7. a kind of solid state battery, comprising: negative electrode material, composite solid electrolyte piece and anode composite.

8. solid state battery according to claim 7, which is characterized in that the anode composite includes:

Positive electrode, solid electrolyte powder, conductive additive and binder.

9. solid state battery according to claim 8, which is characterized in that the positive electrode is selected from FeS₂、Fe_1-xS、WS₂、 Na₃V₂(PO₄)₃、LiCoO₂、LiFePO₄, NCM or NCA；

The conductive additive is selected from one or more of Ketjen black, acetylene black, Super P, carbon nanotube and graphene.

10. solid state battery according to claim 8, which is characterized in that the binder is selected from ethyl cellulose, gathers inclined fluorine One or more of ethylene, sodium alginate and sodium carboxymethylcellulose.