Silver-carbon negative electrode plate, preparation method thereof and all-solid-state battery

Abstract

The invention provides a silver-carbon negative electrode plate, a preparation method thereof and an all-solid-state battery, the silver-carbon negative electrode plate comprises silver and a Li3N-carbon material, and the Li3N-carbon material is prepared by calcining raw materials; the raw materials comprise a carbon source, a nitrogen source and a lithium molten salt system; the nitrogen source is selected from one or more of melamine, dihydrodiamine, urea and ammonium chloride. A lithium molten salt system is utilized, the structure of a carbon source is regulated and controlled during high-temperature calcination, a specific type of nitrogen source is introduced, and a Li3N modification layer is constructed on the surface and internal gaps of the carbon source and is used as the carbon source in the silver-carbon negative electrode, so that a high-density stacked electrode coating is favorably formed, the specific surface area is small, and side reaction is favorably reduced; the Li3N can improve the diffusion rate of lithium ions, accelerate the migration rate of the lithium ions on the negative electrode side in the charging and discharging process, promote the rapid and uniform deposition of the lithium ions on the current collector side, and avoid the formation of lithium dendrites at the interface, thereby improving the stability and cyclicity of the battery.

Description

Technical Field

[0001] The present invention belongs to the technical field of negative electrode sheets, and particularly relates to a silver-carbon negative electrode sheet, a preparation method thereof, and a all-solid-state battery. Background Art

[0002] In an all-solid-state battery, the solid-solid contact between the electrolyte and the negative electrode interface is poor, and the current density distribution at the interface is uneven during the charge and discharge cycle. Lithium ions are usually deposited between the two interfaces and rapidly nucleate and grow at the place where the current is too large, leading to the problem of lithium dendrites and causing battery short circuit. Therefore, it is very necessary to promote the rapid transfer of lithium ions at the negative electrode interface and inside, and to achieve uniform and dense deposition on one side of the current collector, so as to inhibit the formation and growth of lithium dendrites. Summary of the Invention

[0003] In view of this, the purpose of the present invention is to provide a silver-carbon negative electrode sheet, a preparation method thereof, and a all-solid-state battery. The silver-carbon negative electrode sheet can improve the rapid transfer of lithium ions at the negative electrode interface and inside; enhance the interface contact with the electrolyte layer, promote the uniform and rapid deposition of lithium on the current collector side, and further improve the stability of the battery system.

[0004] The present invention provides a silver-carbon negative electrode sheet, which includes silver and Li 3 N-carbon material;

[0005] The Li 3 N-carbon material is obtained by calcining raw materials; the raw materials include a carbon source, a nitrogen source, and a lithium molten salt system;

[0006] The nitrogen source is selected from one or more of melamine, dihydrodiamine, urea, and ammonium chloride.

[0007] Preferably, the carbon source is selected from one or more of mesophase carbon microspheres, graphite, graphene, carbon black, carbon nanofibers, and carbon nanotubes;

[0008] The lithium molten salt system is selected from one or more of LiCl, LiF, LiI, LiBr, LiNO 3 , LiCl-LiF, LiCl-LiBr, and LiCl-LiI.

[0009] Preferably, the mass ratio of the carbon source, the nitrogen source, and the lithium molten salt system is (4.8-5.2):1:(19-21).

[0010] The present invention provides a preparation method of the silver-carbon negative electrode sheet according to the above technical solution, which is characterized by including the following steps:

[0011] Disperse the lithium molten salt system, the nitrogen source, and the carbon source into a solvent, stir evenly, and obtain a precursor dispersion;

[0012] Evaporate the solvent from the precursor dispersion, grind it, and calcine it in an inert atmosphere to obtain a calcined product;

[0013] Wash the calcined product with water and dry it to obtain Li 3 N-carbon material;

[0014] Ball-mill silver powder and the Li 3 N-carbon material in a glue solution to obtain a slurry;

[0015] Coat the slurry and dry it to obtain a silver-carbon negative electrode sheet.

[0016] Preferably, the particle size of the silver powder is 20-60 μm;

[0017] The glue solution is PVDF-NMP or PAALi-H 2 O.

[0018] Preferably, the calcination temperature is 500-600 °C, the heating rate of calcination is 4-5 °C / min, and the calcination time is 3.5-4.5 h.

[0019] The present invention provides a all-solid-state battery, which is prepared by the following method:

[0020] Coat the electrolyte slurry on the silver-carbon negative electrode sheet described in the above technical solution, and dry it to obtain a composite negative electrode sheet;

[0021] After die-cutting the composite negative electrode sheet and the positive electrode sheet, scrape off the material coated on the tab, bond them, encapsulate them, perform warm isostatic pressing, weld the tab, and encapsulate them again to obtain an all-solid-state battery.

[0022] Preferably, the conditions of warm isostatic pressing are: pressure is 300-500 MPa, temperature is 80-120 °C, and time is 9-11 min.

[0023] Preferably, the electrolyte slurry is a P04H electrolyte slurry prepared with an IBIB-NBR glue solution.

[0024] Preferably, when the all-solid-state battery is tested for performance, the pressure applied to the battery is 4 MPa, and the test temperature is 55 °C.

[0025] The present invention provides a silver-carbon negative electrode sheet, which includes silver and Li 3 N-carbon material; the Li 3 N-carbon material is obtained by calcining raw materials; the raw materials include a carbon source, a nitrogen source, and a lithium molten salt system; the nitrogen source is selected from one or more of melamine, dihydrodiamine, urea, and ammonium chloride. The present invention utilizes the lithium molten salt system to regulate the structure of the carbon source during high-temperature calcination, and introduces a specific type of nitrogen source to construct a Li 3 N modification layer on the surface and internal pores of the carbon source, and incorporate Li3 The N-carbon material is used as a carbon source in the silver-carbon negative electrode. If it is a spherical particle carbon source (such as mesophase carbon microspheres), it is beneficial to form a high-density electrode coating with a small specific surface area, which is conducive to reducing side reactions; the in-situ formed Li 3 N can improve the diffusion rate of lithium ions, accelerate the migration rate of lithium ions on the negative electrode side during the lithium-ion charge and discharge process, promote its rapid and uniform deposition on the current collector side, avoid the formation of lithium dendrites at the interface, and thus improve the stability and cycle performance of the battery. Description of the Drawings

[0026] Figure 1 SEM characterization and Mapping analysis diagram of the raw material mesophase carbon microspheres used in Example 1;

[0027] Figure 2 For the SEM characterization and Mapping analysis diagram of Li 3 N-mesophase carbon microspheres in Example 1;

[0028] Figure 3 SEM characterization and Mapping analysis diagram of the silver-carbon negative electrode sheet in Example 1;

[0029] Figure 4 Cycling performance test diagram of the battery prepared in Example 1;

[0030] Figure 5 SEM characterization and Mapping analysis diagram of the raw material melamine in Example 2 of the present invention;

[0031] Figure 6 SEM characterization and Mapping analysis diagram of C65 in Example 2;

[0032] Figure 7 For the SEM characterization and Mapping analysis diagram of Li 3 N-C65 in Example 2;

[0033] Figure 8 Cycling performance test diagram of the battery prepared in Example 2. Detailed Description of the Invention

[0034] The present invention provides a silver-carbon negative electrode sheet, which includes silver and Li 3 N-carbon material;

[0035] The Li 3 N-carbon material is obtained by calcining raw materials; the raw materials include a carbon source, a nitrogen source, and a lithium molten salt system;

[0036] The nitrogen source is selected from one or more of melamine, dihydrodiamine, urea, and ammonium chloride.

[0037] The present invention utilizes a lithium molten salt system to regulate the structure of the carbon source during high-temperature calcination, and introduces a specific type of nitrogen source to construct a Li 3 N modification layer on the surface and internal voids of the carbon source, and uses the Li 3 N-carbon material as the carbon source in the silver-carbon negative electrode. The spherical carbon source (such as mesophase carbon microsphere particles) is conducive to forming a high-density stacked electrode coating, and has a small specific surface area, which is conducive to reducing side reactions; the in-situ formed Li 3 N can improve the diffusion rate of lithium ions, accelerate the migration rate of lithium ions on the negative electrode side during the lithium-ion charge and discharge process, promote its rapid and uniform deposition on the current collector side, and avoid the formation of lithium dendrites at the interface; after preparing the solid electrolyte into a uniform slurry and directly coating it on the surface of the silver-carbon negative electrode, compared with the use of the lamination transfer method, the electrolyte integration method greatly enhances the interfacial contact between the negative electrode sheet and the electrolyte layer, and improves the stability of the battery system.

[0038] The silver-carbon negative electrode sheet provided by the present invention includes silver, and the silver is nanoscale silver powder; the particle size of the silver powder is 20-60 μm, specifically 20 μm, 30 μm, 40 μm, 50 μm or 60 μm;

[0039] The silver-carbon negative electrode sheet provided by the present invention includes Li 3 N-carbon material; the Li 3 N-carbon material is obtained by calcining raw materials; the raw materials include a carbon source, a nitrogen source and a lithium molten salt system.

[0040] In the present invention, the carbon source is selected from one or more of mesophase carbon microspheres, graphite, graphene, carbon black, carbon nanofibers and carbon nanotubes, preferably mesophase carbon microspheres or carbon black; the nitrogen source is selected from one or more of melamine, dihydrodiamine, urea and ammonium chloride, preferably melamine. The lithium molten salt system in the present invention is selected from one or more of LiCl, LiF, LiI, LiBr, LiNO 3 , LiCl-LiF, LiCl-LiBr and LiCl-LiI. In the present invention, the mass ratio of the carbon source, the nitrogen source and the lithium molten salt system is (4.8-5.2):1:(19-21). In specific embodiments, the mass ratio of the carbon source, the nitrogen source and the lithium molten salt system is 5:1:20.

[0041] In the present invention, the mass ratio of the silver and the Li 3 N-carbon material is 1:2.5-3.5, preferably 1:2.9-3.2, more preferably 1:3.

[0042] In the present invention, due to the presence of metallic silver, the silver-carbon negative electrode itself has a good affinity with lithium, can effectively reduce the nucleation energy of lithium, accelerate the transmission rate of lithium ions inside the silver-carbon negative electrode, and achieve deposition on the current collector; the carbon material with Li 3The N-functional layer has high ionic conductivity characteristics, which further accelerates the transport rate of lithium ions at the anode interface and inside, slows down the lithium deposition reaction at the interface, and promotes the rapid and uniform deposition of lithium ions on the current collector side.

[0043] The present invention provides a method for preparing the silver-carbon anode sheet described in the above technical solution, which is characterized by including the following steps:

[0044] Disperse the lithium molten salt system, nitrogen source and carbon source into a solvent, stir evenly to obtain a precursor dispersion;

[0045] Evaporate the solvent from the precursor dispersion, grind it and then calcine it in an inert atmosphere to obtain a calcined product;

[0046] Wash the calcined product with water and dry it to obtain Li 3 N-carbon material;

[0047] Ball-mill the silver powder and the Li 3 N-carbon material in a glue solution to obtain a slurry;

[0048] Coat and dry the slurry to obtain a silver-carbon anode sheet.

[0049] In the present invention, the lithium molten salt system, nitrogen source and carbon source are dispersed into a solvent, stirred evenly to obtain a precursor dispersion. The solvent used in the dispersion is selected from polar low-toxic solvents, preferably one or more of anhydrous ethanol, deionized water and ethylene glycol. The present invention preferably first disperses the lithium molten salt system, carbon source and nitrogen source into the solvent, ultrasonically disperses for 4-6 min, and then magnetically stirs for 110-130 min to obtain a precursor dispersion.

[0050] After obtaining the precursor dispersion, the present invention evaporates the solvent from the precursor dispersion, grinds it and then calcines it in an inert atmosphere to obtain a calcined product. In the present invention, the evaporation of the solvent is preferably carried out under oil bath conditions and with stirring; the temperature provided by the oil bath is 100 °C, and the stirring rate is 550-650 rpm. The present invention fully grinds the evaporated material and places it in a tube furnace for calcination; the calcination is carried out in an inert atmosphere; the calcination temperature is 500-600 °C, and the calcination time is 3.5-4.5 h; the present invention preferably raises the temperature to the calcination temperature at a heating rate of 4-5 °C / min. After the calcination is completed, it is cooled to room temperature, and the calcination is ended.

[0051] The present invention washes the calcined material with water; the washing temperature is 75-85 °C; the washing is carried out under stirring conditions, and the stirring rate is 550-650 rpm; the washing time is 4.5-5.5 h. The present invention washes away the excess molten salt system by washing with water; after the washing is completed, suction filtration and drying are carried out, and it is placed in an oven for drying and standby to obtain Li 3 N-carbon material.

[0052] Obtain Li 3 After obtaining the Li 3 N-carbon material, the present invention ball-mills silver powder and the Li 2 N-carbon material in a glue solution to obtain a slurry. In the present invention, the glue solution is selected from PVDF-NMP or PAALi-H

[0053] The Li 3 The mass ratio of the N-carbon material to the silver powder is 2.5 to 3.5:1, preferably 2.9 to 3.2:1, and more preferably 3:1.

[0054] The ball-milling beads used for ball-milling in the glue solution in the present invention are a mixture of 4 ZrO 2 spherical beads with a diameter of 10 mm, 6 with a diameter of 8 mm, and 24 with a diameter of 6 mm; the rotation speed of ball-milling is 280 to 320 rpm, and the ball-milling time is 11 to 13 h; in a specific embodiment, the rotation speed of ball-milling is 300 rpm, and the ball-milling time is 12 h.

[0055] After obtaining the slurry, the present invention coats and dries the slurry to obtain a silver-carbon negative electrode sheet. The current collector for coating is a 12-μm copper foil or a 12-μm stainless steel foil. After ball-milling, a coating thickness of 60 μm to 120 μm is used with a four-sided scraper to coat on a current collector with a thickness of 12 μm to prepare a silver-carbon electrode sheet, which is dried overnight and then reserved.

[0056] The present invention provides a all-solid-state battery, which is prepared by the following method:

[0057] Coat an electrolyte slurry on the silver-carbon negative electrode sheet described in the above technical solution, and dry it to obtain a composite negative electrode sheet;

[0058] After die-cutting the composite negative electrode sheet and the positive electrode sheet, scrape off the materials coated on the tabs, fit them, encapsulate them, perform warm isostatic pressing, weld the tabs, and encapsulate them again to obtain a all-solid-state battery.

[0059] The present invention coats an electrolyte slurry on the silver-carbon negative electrode sheet described in the above technical solution, and dries it to obtain a composite negative electrode sheet. In the present invention, the electrolyte slurry includes a 5 wt% IBIB-NBR glue solution, a P04H electrolyte powder, and an IBIB solvent, and their mass ratio is 4:4:3.3. When preparing the electrolyte slurry, zirconium beads are used for ball-milling; the diameter of the zirconium beads is 3 mm. After ball-milling, it is defoamed, coated on the silver-carbon negative electrode sheet, and vacuum-dried overnight to obtain a composite negative electrode sheet.

[0060] After obtaining the composite negative electrode sheet, the present invention die-cuts the composite negative electrode sheet and the positive electrode sheet, scrapes off the materials coated on the tabs, fits them, encapsulates them, performs warm isostatic pressing, welds the tabs, and encapsulates them again to obtain a all-solid-state battery.

[0061] In the present invention, the positive electrode sheet is prepared by pulping in a two-step wet mixing method; in the first step, C45, LPSCl electrolyte powder, p-xylene, and 8 wt% PIB-p-xylene colloidal solution are mixed and ball-milled, degassed, then NCM H3, p-xylene, and 8 wt% PIB-p-xylene colloidal solution are added, degassed again, coated, and dried to obtain the positive electrode sheet. Preferably, in the present invention, a coating thickness of 400 μm with a four-sided blade is coated on a 20-μm-thick aluminum foil current collector, and it is reserved after vacuum drying overnight.

[0062] In the present invention, the positive electrode sheet is die-cut into a size of 2 cm × 3 cm, the size of the composite negative electrode sheet is 2.5 cm × 3.5 cm, the materials coated on the positive and negative electrode tabs are scraped off, and then the mass of the positive electrode sheet is weighed and recorded, and a 5 cm × 6 cm PET board is used for electrode sheet lamination.

[0063] After the lamination is completed, preferably, in the present invention, an aluminum foil bag is used for vacuum packaging, and then warm isostatic pressing is carried out to make the electrode sheets closely adhere; the conditions of the warm isostatic pressing are: the pressure is 300 - 500 MPa, the temperature is 80 - 120 °C, and the time is 10 min.

[0064] After the warm isostatic pressing, the electrode tabs are welded, and vacuum packaging is carried out with an aluminum foil bag. Finally, it is fixed with a stainless steel plate fixture, and 4 layers of sulfuric acid paper and one layer of silica gel pad are placed between the soft-pack battery and the clamping plate as a buffer layer. Thus, the assembly of the soft-pack battery is completed.

[0065] In the present invention, the battery performance test is carried out in an oven, the applied pressure of the battery is 4 MPa, and the test temperature is 55 °C.

[0066] Starting from the perspective of the modified silver-carbon negative electrode carbon material, in the present invention, a functional layer for improving the rapid lithium-ion transmission is constructed on the surface and inside the pores of the carbon material. After being uniformly mixed and dispersed with silver powder, it is prepared into a silver-carbon negative electrode sheet, which is used as the negative electrode structure of the all-solid-state lithium-ion battery to enhance the rapid transfer of lithium ions at the negative electrode interface and inside; at the same time, the solid electrolyte is prepared into a uniform slurry and directly coated on the surface of the modified silver-carbon negative electrode. Compared with the electrolyte integration method using the lamination and transfer method, the interfacial contact between the negative electrode and the electrolyte layer is greatly enhanced, further enhancing the rapid transfer of lithium ions at the negative electrode interface and inside, and promoting the uniform and rapid deposition of lithium on the side of the negative electrode sheet and the current collector. Due to the presence of metallic silver, the silver-carbon negative electrode sheet itself has a good affinity with lithium, which can effectively reduce the nucleation energy of lithium, promote the transmission rate of lithium ions, and deposit on the current collector. At the same time, the Li 3 N functional layer on the carbon material has high ionic conductivity characteristics, which improves the rapid and uniform deposition of lithium ions, thereby enhancing the stability of the battery system. The two interact with each other to jointly improve the performance of the battery system.

[0067] The method provided by the present invention is green and economical. The molten salt system used has a low price and can still be recycled during the subsequent suction filtration process. The operation process is simple and does not require complex equipment, which can accelerate the transmission rate of lithium ions at the negative electrode interface and inside.

[0068] To further illustrate the present invention, a silver-carbon negative electrode sheet, a preparation method thereof, and a all-solid-state battery provided by the present invention will be described in detail below with reference to embodiments, but they should not be construed as limiting the protection scope of the present invention.

[0069] In the following embodiments, IBIB: isobutyl isobutyrate; P04H: electrolyte model, belonging to LPSCl electrolyte; PIB: polyisobutylene; NBR: nitrile rubber; NCM H3: nickel-cobalt-manganese ternary cathode material model; C45 conductive carbon model; PET: polyethylene terephthalate resin; PAALi: lithium polyacrylate;

[0070] Example 1

[0071] 1) Disperse 15.37 g of LiCl, 4.63 g of LiF, 1.0 g of melamine, and 5 g of mesophase carbon microspheres into 200 mL of absolute ethanol. After ultrasonic dispersion for 5 min and magnetic stirring for 2 h, a uniform precursor dispersion liquid is obtained. After completion, in an oil bath at 100 °C, stir and evaporate the solvent at 600 r / min;

[0072] 2) Grind the evaporated material thoroughly and place it in a tube furnace. Use N 2 as an inert atmosphere for high-temperature calcination. The heating rate is 5 °C / min, and calcine at 550 °C for 4 h;

[0073] 3) After calcination, perform water washing under the conditions of 80 °C - 600 r / min - 5 h. After suction filtration, place it in an oven at 60 °C and dry overnight to obtain Li 3 N-mesophase carbon microspheres;

[0074] 4) Take 4.5 g of Li 3 N-mesophase carbon microspheres and silver powder are mixed at a mass ratio of 3:1, and ball-milled with 1 wt% PAALi-H 2 O glue solution at a mass ratio of 1:4.5. The ball-milling beads are 4 ZrO 2 spherical beads with a diameter of 10 mm, 6 with a diameter of 8 mm, and 24 with a diameter of 6 mm. The rotation speed is 300 r / min, and the ball-milling time is 12 h. After completion, use a four-sided scraper to coat with a thickness of 60 μm on a copper foil current collector with a thickness of 12 μm to obtain a silver-carbon negative electrode sheet, and dry it overnight for standby;

[0075] 5) Use 4.0 g of 5 wt% IBIB-NBR glue solution, 4.0 g of P04H electrolyte powder, 3.3 g of IBIB solvent, and 20 ZrO with a diameter of 3 mm2 The spherical beads are placed in a 50 mL degassing tank and prepared with electrolyte slurry. The degassing machine is run twice at 300 rpm-900 rpm-120 s and 600 rpm-900 rpm-600 s (rotation speed-revolution speed-time (seconds)) to make slurry. The beads are coated on the surface of the silver-carbon negative electrode sheet with a coating thickness of 100 μm using a four-sided scraper. The negative electrode and the electrolyte layer are integrated and vacuum dried overnight for use.

[0076] 6) The positive electrode sheet is slurried by a two-step wet mixing method. 0.4g C45, 2.8g LPSCl electrolyte powder, 10g p-xylene and 4g 8wt% PIB-p-xylene glue are added with 4 8mm and 16 6mm ball mills, and mixed by a degassing procedure of 200rpm-900rpm-900s once and 300rpm-900rpm-900s twice. After the degassing, 16g NCM H3, 2g p-xylene and 6g 8wt% PIB-p-xylene glue are added, and the slurry is continued by the above two-step degassing and mixing method. After the degassing, a four-sided scraper is used to apply a coating thickness of 400μm on a 20μm thick aluminum foil current collector. The positive electrode sheet is prepared and dried in a vacuum oven overnight for use;

[0077] 7) Die-cut the prepared composite negative electrode and positive electrode sheets. The size of the positive electrode is 2cm*3cm, and the size of the negative electrode is 2.5cm*3.5cm. Scrape off the materials coated on the positive and negative electrode tabs, then weigh and record the mass of the positive electrode sheet, and use a 5cm*6cm PET plate for electrode sheet bonding;

[0078] 8) After the bonding is completed, vacuum packaging is performed in an aluminum foil bag, followed by warm isostatic pressing at 300Mpa-1000℃-10min, so that the pole pieces are tightly bonded under high temperature and high pressure;

[0079] 9) After warm isostatic pressing, the pole ears are welded and vacuum packaged with aluminum foil bags. Finally, they are fixed with stainless steel plate clamps. Four layers of sulfuric acid paper and one layer of silicone pad are placed between the soft-pack battery and the clamp as a buffer layer. At this point, the soft-pack battery assembly is completed.

[0080] The present invention performs a performance test of a battery in an oven, the applied pressure of the battery is 4 MPa, and the test temperature is 55°C.

[0081] The present invention performs SEM characterization and mapping analysis on the raw material mesophase carbon microspheres to observe the morphology. The results are as follows Figure 1 As shown in the figure, it can be seen that the mesocarbon microspheres are spherical particles, the carbon sphere particles are relatively uniform, and the particle size is about 10-20μm. Mapping analysis shows that the C and O elements are evenly distributed.

[0082] The present invention is to 3SEM characterization and Mapping analysis were carried out on N-mesophase carbon microspheres, and the results are as Figure 2 shown. It can be seen that the spherical particle morphology and particle size of the mesophase carbon microspheres before and after calcination did not change significantly, and there was little difference from that before modification. The Mapping analysis shows that the distributions of the four elements C, Cl, N, and F are uniform, indicating good doping state, and Li 3 N was successfully introduced.

[0083] SEM characterization and Mapping analysis were carried out on the prepared silver-carbon negative electrode sheet in the present invention, and the results are as Figure 3 shown. Figure 3 In a and b are the plane of the electrode sheet of Li 3 N-modified mesophase carbon microspheres. It can be seen that the spherical particles of the mesophase carbon microspheres are damaged after ball milling overnight and become irregular blocks and lamellar structures. Figure 3 The cross-section of the electrode sheet in c and d shows that the thickness is about 30 μm. The Mapping analysis shows that the distributions of the five elements Ag, C, Cl, N, and F are relatively uniform, and the properties of the electrode sheet are relatively excellent.

[0084] Figure 4 are the test results of the stability and cycle performance of the battery prepared in Example 1. It can be Figure 4 seen that: after 80 charge-discharge cycles of the mesophase carbon microspheres modified by Li 3 N, the discharge specific capacity is 103.5 mAh g -1 , and the capacity retention rate is 69.4%. The reversible specific capacity is improved compared with that before modification, and the stability is improved, indicating that the modification of Li 3 N on the mesophase carbon microspheres plays a positive role.

[0085] Example 2

[0086] 1) 5.0 g of LiCl, 0.5 g of melamine, and 1.0 g of C65 (conductive carbon black model) were dispersed in 200 mL of absolute ethanol. After ultrasonic dispersion for 5 min and magnetic stirring for 2 h, a uniform precursor dispersion was obtained. After that, the solvent was evaporated by stirring at 600 r / min in an oil bath at 100 °C;

[0087] 2) The evaporated material was thoroughly ground and placed in a tube furnace. N 2 was used as an inert atmosphere for high-temperature calcination. The heating rate was 5 °C / min, and calcination was carried out at 550 °C for 4 h;

[0088] 3) After calcination, water washing was carried out under the conditions of 80 °C - 600 r / min - 5 h. After suction filtration, it was placed in an oven at 60 °C overnight to dry, and Li 3 N-C65 was obtained;

[0089] 4) Take 0.6 g of Li3 N-C65 and silver powder were mixed in a mass ratio of 3:1 and 1wt% PAALi-H 2 The ZrO gel was ball milled at a mass ratio of 1:4.5, and the ball milling beads were 4 with a diameter of 10 mm, 6 with a diameter of 8 mm, and 24 with a diameter of 6 mm. 2 Spherical beads, rotating speed 300r / min, ball milling time 12h. After finishing, use a four-sided scraper with a coating thickness of 60μm, and coat it on a 12μm thick copper foil current collector to obtain a silver-carbon negative electrode sheet, which is dried overnight for use;

[0090] 5) 4.0 g 5 wt% IBIB-NBR glue, 4.0 g P04H electrolyte powder, 3.3 g IBIB solvent and 20 ZrO particles with a diameter of 3 mm were used. 2 The spherical beads are placed in a 50 mL degassing tank to prepare electrolyte slurry, and the degassing machine is run twice with the program of 3-9-120 and 6-9-600 to make slurry, and a four-sided scraper is used to coat the surface of the silver-carbon negative electrode sheet with a coating thickness of 100 μm. The negative electrode and the electrolyte layer are integrated, and vacuum dried overnight for use;

[0091] 6) The positive electrode sheet is slurried by a two-step wet mixing method. 0.4g C45, 2.8g LPSCl electrolyte powder, 10g p-xylene and 4g 8wt% PIB-p-xylene glue are added with 4 8mm and 16 6mm ball mills, and mixed by a degassing procedure of 2-9-900 once and 3-9-900 twice. After the degassing, 16g NCM H3, 2g p-xylene and 6g 8wt% PIB-p-xylene glue are added, and the slurry is continued by the above two-step degassing and mixing method. After the degassing, a four-sided scraper is used to apply a coating thickness of 400μm on a 20μm thick aluminum foil current collector. The positive electrode sheet is prepared and dried in a vacuum oven overnight for use;

[0092] 7) Die-cut the prepared composite negative electrode and positive electrode sheets. The size of the positive electrode is 2cm*3cm, and the size of the negative electrode is 2.5cm*3.5cm. Scrape off the materials coated on the positive and negative electrode tabs, then weigh and record the mass of the positive electrode sheet, and use a 5cm*6cm PET plate for electrode sheet bonding;

[0093] 8) After the bonding is completed, vacuum packaging is performed in an aluminum foil bag, followed by warm isostatic pressing at 300Mpa-100℃-10min, so that the pole pieces are tightly bonded under high temperature and high pressure;

[0094] 9) After warm isostatic pressing, the pole ears are welded and vacuum packaged with aluminum foil bags. Finally, they are fixed with stainless steel plate clamps. Four layers of sulfuric acid paper and one layer of silicone pad are placed between the soft-pack battery and the clamp as a buffer layer. At this point, the soft-pack battery assembly is completed.

[0095] The performance test of the battery is carried out in an oven, the applied pressure of the battery is 4 MPa, and the test temperature is 55 °C.

[0096] The present invention conducts SEM characterization and Mapping analysis on the raw material melamine to observe the morphology, and the results are as Figure 5 shown; it can be seen that: melamine is irregular small particles, the dispersion is relatively uniform, there is no agglomeration phenomenon, and the particle size is about 30 - 50 μm. The Mapping spectrum test shows that the material contains two elements, C and N, and the distribution is relatively uniform, without large clusters generated, which is consistent with the material itself.

[0097] The present invention conducts SEM characterization and Mapping analysis on the raw material C65 to observe the morphology, and the results are as Figure 6 shown; it can be seen that: the morphology of the carbon source C65 used is spherical small particles adhered together, the carbon sphere particles are relatively uniform, and the particle size is about 50 - 60 μm. The Mapping analysis shows that it contains two elements, C and O, and the distribution is uniform.

[0098] The present invention conducts SEM characterization and Mapping analysis on Li 3 N-C65, and the results are as Figure 7 shown. It can be seen that: the morphology of C65 after modification has not changed significantly. The Mapping test contains three elements, C, N, and Cl, and the N element is successfully introduced, and the element distribution is uniform. The surface of the N-C65Ag electrode is relatively flat, without large particles and agglomeration phenomena, and the surface is smooth and not mottled. The Mapping analysis shows four elements, Ag, C, N, and Cl, and the distribution is relatively uniform, and the properties of the electrode are excellent.

[0099] For the soft-pack battery assembled with C65 before and after modification at 300 Mpa - 100 °C - 10 min, using the Li 2 ZrO 3 -coated NCM H3 positive electrode, the charge-discharge cycle performance test at 0.1C / 0.2C is as Figure 8 shown: after being modified by Li 3 N, the stability of the Ag-Li 3 N@C65-P04H-LZO-NCMH3 soft-pack battery system has been greatly improved. After 85 charge-discharge cycles at 0.1C / 0.2C, the discharge specific capacity is 111.8 mAh g -1 , and the capacity retention rate is 78%. Li 3 N plays a positive role in the modification of C65.

[0100] From the above embodiments, it can be seen that the present invention provides a silver-carbon negative electrode sheet, including silver and Li 3 N-carbon material; the Li 3The N-carbon material is obtained by calcining raw materials; the raw materials include a carbon source, a nitrogen source, and a lithium molten salt system; the nitrogen source is selected from one or more of melamine, dihydrodiamine, urea, and ammonium chloride. The present invention utilizes the lithium molten salt system to regulate the structure of the carbon source during the high-temperature calcination process, and introduces a specific type of nitrogen source to construct a Li 3 N modification layer on the surface and internal voids of the carbon source, and uses the Li 3 N-carbon material as the carbon source in the silver-carbon negative electrode. The spherical particles of the mesophase carbon microspheres are beneficial to the formation of a high-density packed electrode coating, and have a small specific surface area, which is beneficial to reducing side reactions; the in-situ formed Li 3 N can improve the diffusion rate of lithium ions, accelerate the migration rate of lithium ions on the negative electrode side during the lithium-ion charge and discharge process, promote its rapid and uniform deposition on the current collector side, avoid the formation of lithium dendrites at the interface, and thus improve the stability and cycle performance of the battery.

[0101] The above are only the preferred embodiments of the present invention. It should be noted that for those of ordinary skill in the art, without departing from the principle of the present invention, several improvements and refinements can be made, and these improvements and refinements should also be regarded as the protection scope of the present invention.

Claims

1. A silver-carbon negative electrode sheet, characterized in that: Including silver and Li3N-carbon materials; The Li3N-carbon material is prepared by calcining raw materials; the raw materials include a carbon source, a nitrogen source and a lithium molten salt system; The nitrogen source is selected from one or more of melamine, dihydrogen diamine, urea and ammonium chloride.

2. The silver-carbon negative electrode sheet according to claim 1, characterized in that: The carbon source is selected from one or more of mesocarbon microspheres, graphite, graphene, carbon black, carbon nanofibers and carbon nanotubes; The lithium molten salt system is selected from one or more of LiCl, LiF, LiI, LiBr, LiNO3, LiCl-LiF, LiCl-LiBr and LiCl-LiI.

3. The silver-carbon negative electrode according to claim 1, characterized in that: The mass ratio of the carbon source, the nitrogen source and the lithium molten salt system is (4.8-5.2):1:(19-21).

4. A method for preparing the silver-carbon negative electrode sheet according to claim 1, characterized in that: The following steps are involved: Dispersing the lithium molten salt system, the nitrogen source and the carbon source in a solvent, and stirring evenly to obtain a precursor dispersion; The precursor dispersion is evaporated to dryness of solvent, ground and then calcined in an inert atmosphere to obtain a calcined product; The calcined product is washed with water and dried to obtain a Li3N-carbon material; Ball milling the silver powder and the Li3N-carbon material in a colloid to obtain a slurry; The slurry is coated and dried to obtain a silver-carbon negative electrode sheet.

5. The preparation method according to claim 4, characterized in that: The particle size of the silver powder is 20 to 60 μm; The glue is PVDF-NMP or PAALi-H2O.

6. The preparation method according to claim 4, characterized in that: The calcination temperature is 500-600° C., the calcination heating rate is 4-5° C. / min, and the calcination time is 3.5-4.5 h.

7. An all-solid-state battery is prepared according to the following method: Coating the electrolyte slurry on the silver-carbon negative electrode sheet according to claim 1, and drying to obtain a composite negative electrode sheet; After the composite negative electrode sheet and positive electrode sheet are die-cut, the material coated on the tabs is scraped off, the sheets are bonded, packaged, warm isostatically pressed, the tabs are welded, and packaged again to obtain an all-solid-state battery.

8. The all-solid-state battery according to claim 7, characterized in that: The conditions of the warm isostatic pressing are: pressure of 300-500 MPa, temperature of 80-120° C., and time of 9-11 min.

9. The all-solid-state battery according to claim 7, characterized in that: The electrolyte slurry is P04H electrolyte slurry prepared by IBIB-NBR glue.

10. The all-solid-state battery according to claim 7, characterized in that: During the performance test of the all-solid-state battery, the pressure applied to the battery was 4MPa and the test temperature was 55°C.

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