A silicon-lithium battery anode and a silicon-lithium battery having the anode

Abstract

The present invention belongs to the technical field of batteries, and particularly relates to a negative electrode of a silicon lithium battery and a silicon lithium battery having the negative electrode. A negative electrode of a silicon lithium battery is prepared from polyacrylamide, aniline, silicon nanoparticles, negatively charged silver-polyphosphazene microspheres, and ammonium persulfate with a mass ratio of 2-5:2-8:8-14:2-5:3-5. The negatively charged silver-polyphosphazene microspheres are crosslinked from hexachlorocyclotriphosphazene and hydroxylated negatively charged silver particles under the catalysis of triethylamine. The silver particles in the hydroxylated negatively charged silver particles are prepared by in-situ reduction of silver nitrate in an aqueous sodium alginate solution. The present invention improves the electrical conductivity of the silicon negative electrode and the contact area with the positive electrode plate. During the silicon expansion process, it prevents the positive electrode plate from being broken due to high deformation, improves the stability of the battery structure, and increases the number of cycles.

Description

Technical Field

[0001] The present invention belongs to the technical field of batteries, and particularly relates to a negative electrode of a silicon lithium battery and a silicon lithium battery having the negative electrode. Background Art

[0002] The demand for fast charging and discharging of mobile power sources by electric vehicles and portable electronic products is increasing day by day, which stimulates the development of research work on high-performance electrochemical energy storage devices. The key to developing high-performance lithium-ion batteries is to develop positive / negative electrode materials with high specific energy and long life. At present, the specific capacity of the positive electrode material has been doubled, so improving the specific capacity of the negative electrode material is a necessary task for the development of current high-performance lithium-ion batteries. Currently, the negative electrode of commercial lithium-ion batteries uses graphite-based materials, which have approached the theoretical capacity and it is difficult to improve further.

[0003] Silicon has become the most promising negative electrode material for lithium batteries due to its high theoretical specific capacity (4200 mAh / g), moderate lithium intercalation potential (~0.4V vs Li / Li+), and the advantage of being abundant in nature. However, during the process of lithium intercalation / deintercalation, silicon undergoes a phase change process between amorphous and crystalline states, which causes huge volume expansion and contraction. The mechanical stress caused by the huge volume change makes itself pulverize, and even the entire electrode collapses, greatly shortening the service life of the battery. Therefore, it is urgent to invent a silicon-based electrode with better flexibility to adapt to the volume expansion and contraction changes and improve the battery cycle effect.

[0004] In addition, during the preparation process of the electrode sheet slurry, a conductive agent needs to be added to improve its conductivity. Commonly used conductive agents are mainly granular conductive carbon black, carbon fiber, etc. However, due to the small particle size of conductive agents such as conductive carbon black, they are easily agglomerated and cannot form a good conductive network well, and it is difficult to meet the need for greatly improving the power performance, affecting the stability of the battery cycle. Therefore, how to select a suitable conductive agent and make the conductive agent uniformly dispersed is of great significance for improving the electrical performance of lithium-ion capacitors. Summary of the Invention

[0005] (1) Technical Problems to be Solved

[0006] Aiming at the deficiencies of the prior art, the present invention provides a negative electrode of a silicon lithium battery, which solves the problem of poor stability of the silicon-based electrode during the battery cycle process.

[0007] (2) Technical Solutions

[0008] In order to solve the above problems, the present invention provides the following technical solutions: a silicon-lithium battery negative electrode is prepared from polyacrylamide, aniline, silicon nanoparticles, negatively charged silver-polyphosphazene microspheres and ammonium persulfate in a mass ratio of 2-5:2-8:8-14:2-5:3-5, wherein the negatively charged silver-polyphosphazene microspheres are cross-linked with hexachlorocyclotriphosphazene and hydroxylated negatively charged silver particles under the catalysis of triethylamine, the silver particles in the hydroxylated negatively charged silver particles are prepared by in-situ reduction of silver nitrate in a sodium alginate aqueous solution, and the diameter of the silicon nanoparticles is 50-80 nm.

[0009] The present invention provides a method for preparing a negative electrode of a silicon-lithium battery, the steps of which are as follows:

[0010] (1) Preparation of negatively charged silver particles

[0011] Adding a silver nitrate solution dropwise to a sodium alginate aqueous solution with a pH of 8-13, stirring to obtain a mixture, adding an ascorbic acid solution dropwise to the mixture, ultrasonically treating the mixed system, centrifuging to discard the supernatant, washing with distilled water, placing the precipitate in a -80°C refrigerator for 1-2 days, and then freeze-drying at -40°C for 1-3 days to obtain sodium alginate nanosilver particles;

[0012] (2) Preparation of hydroxylated negatively charged silver particles

[0013] Dissolving sodium alginate nanosilver particles in deionized water, then adding glycolic acid, then adding hydrochloric acid, stirring until the reaction is complete, then pouring the resulting reaction mixture into ethanol for filtration, washing the precipitate with ethanol, and drying at room temperature to obtain hydroxylated negatively charged silver particles;

[0014] (3) Preparation of negatively charged silver-polyphosphazene microspheres

[0015] In a nitrogen atmosphere, hexachlorocyclotriphosphazene and hydroxylated negatively charged silver particles are dispersed in anhydrous acetonitrile, triethylamine is added after stirring, and the mixture is heated for reaction. After the reaction is completed, the product is collected by centrifugation, washed with acetonitrile and ethanol for 3-5 times, and dried in vacuum to obtain negatively charged silver-polyphosphazene microspheres;

[0016] (4) Preparation of solution A

[0017] Add polyacrylamide to deionized water, stir to obtain a polyacrylamide aqueous solution, add negatively charged silver-polyphosphazene microspheres to the polyacrylamide aqueous solution, stir evenly at 45-55° C., add aniline and silicon nanoparticles, and disperse evenly by ultrasonication at room temperature to obtain solution A;

[0018] (5) Preparation of silicon-lithium battery negative electrode

[0019] Ammonium persulfate was added to deionized water to obtain an ammonium persulfate solution. The ammonium persulfate solution was slowly poured into Solution A, and the mixed solution was stirred to make it uniform. The mixed solution was polymerized at a low temperature and then kept at room temperature for 12 - 24 h. The formed hydrogel was slowly washed clean with deionized water to obtain a silicon lithium battery negative electrode.

[0020] Preferably, in step (1), the concentration of the sodium alginate aqueous solution is 10 - 20 mg / mL, the molar concentration of the silver nitrate solution is 40 - 60 mmol / L, and the concentration of the ascorbic acid solution is 5 - 15 mg / L.

[0021] Preferably, in step (1), the volume ratio of the sodium alginate aqueous solution, the silver nitrate solution, and the ascorbic acid solution is 100:1 - 5:1 - 5.

[0022] Preferably, in step (1), the ultrasonic conditions are treatment at 15 - 90 °C with 100 - 900 W for 0.5 - 1.5 h.

[0023] Preferably, in step (2), the mass ratio of deionized water, sodium alginate silver nanoparticles, glycolic acid, and hydrochloric acid is 30 - 50:5 - 10:3 - 6:5 - 10.

[0024] Preferably, in step (2), the reaction conditions are stirring and reacting in the dark at 70 - 90 °C for 2 - 3 h.

[0025] Preferably, in step (3), the mass ratio of hexachlorocyclotriphosphazene, negatively charged silver hydroxide particles, and triethylamine is 15 - 25:100:1 - 2.

[0026] Preferably, in step (3), the reaction conditions are heating and reacting at 90 - 100 °C for 12 - 24 hours.

[0027] Preferably, in step (4), the mass ratio of deionized water and polyacrylamide is 50:2 - 5.

[0028] Preferably, in step (4), the reaction conditions of deionized water and polyacrylamide are stirring at 60 - 90 °C for 2 - 4 h.

[0029] Preferably, in step (5), the mass ratio of ammonium persulfate and deionized water is 3 - 5:10.

[0030] Preferably, in step (5), the reaction conditions of the mixed solution are cooling to 0 - 3 °C for polymerization for 4 - 6 h.

[0031] The present invention also provides a silicon lithium battery, which includes the above-mentioned silicon lithium battery negative electrode, and its preparation method is as follows:

[0032] (1)Coat the silicon-based hydrogel prepared by the present invention on the negative electrode grid plate, and after pressurization and drying, a silicon-based hydrogel negative electrode plate is prepared;

[0033] (2)Select a conventional formula lithium battery positive electrode as the positive electrode plate of the battery, select the above-mentioned silicon-based hydrogel negative electrode plate as the negative electrode plate, use a commercially available battery cell of the corresponding size as the battery cell body, assemble it into the battery cell in the positive electrode - separator - negative electrode manner, and then inject electrolyte into the battery cell body to assemble a silicon-based lithium battery.

[0034] Compared with the prior art, the beneficial technical effects of the present invention are as follows:

[0035] (1)For the negative electrode of a silicon lithium battery of the present invention, ammonium persulfate is used as an initiator to in-situ polymerize to obtain a polyaniline polymer chain; charge interaction occurs between the negatively charged silver - polyphosphazene microspheres and the positively charged polyaniline polymer chain, which promotes the dispersion of the polyaniline polymer chain in the polyacrylamide hydrogel. At the same time, the negatively charged silver - polyphosphazene microspheres and polyaniline can synergistically improve the conductivity. The polyphosphazene in the negatively charged silver - polyphosphazene microspheres can improve the flexibility of the silver conductive agent and enhance the contact with the positive electrode plate. During the silicon expansion process, it can prevent the positive electrode plate from being broken due to high deformation, improve the stability of the battery structure, and increase the number of cycles.

[0036] (2)For the negative electrode of a silicon lithium battery of the present invention, silicon nanoparticles are used as fillers. On the basis of maintaining the inherent tensile strength of the hydrogel, the electrochemical performance of the material is enhanced. Moreover, the hydrogel provides tension for the volume change process of the silicon nanoparticles during lithium intercalation and deintercalation, reduces the pulverization phenomenon of the silicon nanoparticles, and maintains the stability of the battery cycle. Specific Embodiments

[0037] To achieve the above object, the present invention provides the following examples and comparative examples:

[0038] Example 1

[0039] The present invention provides a preparation method for the negative electrode of a silicon lithium battery, and the steps are as follows:

[0040] (1)Prepare negatively charged silver particles

[0041] Dropwise add 2 ml of a silver nitrate solution with a concentration of 40 mmol / L to 100 ml of an aqueous sodium alginate solution with a pH of 8 and a concentration of 10 mg / mL drop by drop, stir evenly to obtain a mixture, then dropwise add 2 ml of an ascorbic acid solution with a concentration of 5 mg / L to the mixture, treat it at 30 °C with 200 W for 1 h, centrifuge to discard the supernatant, wash it with distilled water, place the precipitate in a -80 °C refrigerator and freeze it for 2 d, and then freeze-dry it at -40 °C for 1 d to obtain sodium alginate silver nanoparticles;

[0042] (2) Preparation of hydroxylated negatively charged silver particles

[0043] Dissolve 5 g of sodium alginate silver nanoparticles in 50 ml of deionized water, then add 3 g of glycolic acid, and then add 5 ml of hydrochloric acid. Stir and react under dark conditions at 70 °C for 2 h. Then pour the obtained reaction mixture into ethanol for filtration. Wash the precipitate with ethanol and dry it at room temperature to obtain hydroxylated negatively charged silver particles;

[0044] (3) Preparation of negatively charged silver-polyphosphazene microspheres

[0045] Under a nitrogen atmosphere, disperse 3 g of hexachlorocyclotriphosphazene and 20 g of hydroxylated negatively charged silver particles in 30 ml of anhydrous acetonitrile. After stirring, add 1 g of triethylamine and heat and react at 90 °C for 12 hours. After the reaction is completed, collect the product by centrifugation, wash it 3 times with acetonitrile and ethanol, and dry it under vacuum to obtain negatively charged silver-polyphosphazene microspheres;

[0046] (4) Preparation of Solution A

[0047] Add 2 g of polyacrylamide to 50 ml of deionized water and stir at 60 °C for 2 h to obtain an aqueous polyacrylamide solution. Add 2 g of negatively charged silver-polyphosphazene microspheres to the aqueous polyacrylamide solution, stir evenly at 45 °C, add 3 g of aniline and 8 g of silicon nanoparticles with a diameter of 50 nm, and ultrasonically disperse evenly at room temperature to obtain Solution A;

[0048] (5) Preparation of the negative electrode of a silicon lithium battery

[0049] Add 3 g of ammonium persulfate to 10 ml of deionized water to obtain an ammonium persulfate solution. Slowly pour the ammonium persulfate solution into Solution A, stir the mixed solution to make it uniform, cool the mixed solution to 3 °C and polymerize for 4 h, and then keep it at room temperature for 12 h. Slowly wash the formed hydrogel with deionized water to obtain a negative electrode of a silicon lithium battery.

[0050] Example 2

[0051] The present invention provides a method for preparing a negative electrode of a silicon lithium battery, and the steps are as follows:

[0052] (1) Preparation of negatively charged silver particles

[0053] Dropwise add 2 ml of a silver nitrate solution with a concentration of 50 mmol / L to 100 ml of an aqueous sodium alginate solution with a pH of 9 and a concentration of 15 mg / mL drop by drop, stir evenly to obtain a mixture. Dropwise add 2 ml of an ascorbic acid solution with a concentration of 10 mg / L to the mixture, treat it at 60 °C with 600 W for 1 h, centrifuge and discard the supernatant, wash it with distilled water, place the precipitate in a -80 °C refrigerator and freeze it for 1 d, and then freeze-dry it at -40 °C for 3 d to obtain sodium alginate silver nanoparticles;

[0054] (2) Preparation of negatively charged hydroxylated silver particles

[0055] Dissolve 8 g of sodium alginate silver nanoparticles in 50 ml of deionized water, then add 4 g of glycolic acid, and then add 7 ml of hydrochloric acid. Stir the reaction mixture in the dark at 80 °C for 2 h. Then pour the obtained reaction mixture into ethanol for filtration. Wash the precipitate with ethanol and dry it at room temperature to obtain negatively charged hydroxylated silver particles;

[0056] (3) Preparation of negatively charged silver-polyphosphazene microspheres

[0057] Under a nitrogen atmosphere, disperse 4 g of hexachlorocyclotriphosphazene and 20 g of negatively charged hydroxylated silver particles in 30 ml of anhydrous acetonitrile. After stirring, add 1 g of triethylamine and heat the reaction at 90 °C for 12 hours. After the reaction, collect the product by centrifugation, wash it 3 times with acetonitrile and ethanol, and dry it under vacuum to obtain negatively charged silver-polyphosphazene microspheres;

[0058] (4) Preparation of Solution A

[0059] Add 5 g of polyacrylamide to 50 ml of deionized water and stir at 60 °C for 4 h to obtain an aqueous polyacrylamide solution. Add 4 g of negatively charged silver-polyphosphazene microspheres to the aqueous polyacrylamide solution, stir evenly at 55 °C, add 6 g of aniline and 10 g of silicon nanoparticles with a diameter of 60 nm, and ultrasonically disperse evenly at room temperature to obtain Solution A;

[0060] (5) Preparation of the negative electrode of a silicon lithium battery

[0061] Add 4 g of ammonium persulfate to 10 ml of deionized water to obtain an ammonium persulfate solution. Slowly pour the ammonium persulfate solution into Solution A, stir the mixed solution to make it uniform, cool the mixed solution to 0 °C and polymerize for 4 h, and then keep it at room temperature for 24 h. Slowly wash the formed hydrogel with deionized water to obtain a negative electrode of a silicon lithium battery.

[0062] Example 3

[0063] The present invention provides a method for preparing the negative electrode of a silicon lithium battery, and the steps are as follows:

[0064] (1) Preparation of negatively charged silver particles

[0065] Dropwise add 4 ml of a silver nitrate solution with a concentration of 50 mmol / L to 100 ml of an aqueous sodium alginate solution with a pH of 12 and a concentration of 15 mg / mL drop by drop, stir evenly to obtain a mixture, dropwise add 4 ml of an ascorbic acid solution with a concentration of 12 mg / L to the mixture, treat it at 90 °C with 900 W for 1.5 h, centrifuge and discard the supernatant, wash it with distilled water, place the precipitate in a -80 °C refrigerator and freeze it for 2 d, and then freeze-dry it at -40 °C for 3 d to obtain sodium alginate silver nanoparticles;

[0066] (2) Preparation of hydroxylated negatively charged silver particles

[0067] Dissolve 8 g of sodium alginate silver nanoparticles in 50 ml of deionized water, then add 4 g of glycolic acid, and then add 8 ml of hydrochloric acid. Stir and react under dark conditions at 70 °C for 2 h. Then pour the obtained reaction mixture into ethanol for filtration. Wash the precipitate with ethanol and dry it at room temperature to obtain hydroxylated negatively charged silver particles;

[0068] (3)Preparation of negatively charged silver-polyphosphazene microspheres

[0069] Under a nitrogen atmosphere, disperse 3 g of hexachlorocyclotriphosphazene and 20 g of hydroxylated negatively charged silver particles in 30 ml of anhydrous acetonitrile. After stirring, add 2 g of triethylamine and heat and react at 100 °C for 12 h. After the reaction, centrifuge to collect the product, wash it 5 times with acetonitrile and ethanol, and dry it under vacuum to obtain negatively charged silver-polyphosphazene microspheres;

[0070] (4)Preparation of Solution A

[0071] Add 4 g of polyacrylamide to 50 ml of deionized water and stir at 90 °C for 4 h to obtain an aqueous polyacrylamide solution. Add 4 g of negatively charged silver-polyphosphazene microspheres to the aqueous polyacrylamide solution, stir evenly at 55 °C, add 8 g of aniline and 14 g of silicon nanoparticles with a diameter of 80 nm, and ultrasonically disperse evenly at room temperature to obtain Solution A;

[0072] (5)Preparation of the anode of a silicon lithium battery

[0073] Add 5 g of ammonium persulfate to 10 ml of deionized water to obtain an ammonium persulfate solution. Slowly pour the ammonium persulfate solution into Solution A, stir the mixed solution to make it uniform, cool the mixed solution to 0 °C and polymerize for 6 h, and then keep it at room temperature for 24 h. Slowly wash the formed hydrogel with deionized water to obtain an anode of a silicon lithium battery.

[0074] Example 4

[0075] The present invention provides a method for preparing the anode of a silicon lithium battery, and the steps are as follows:

[0076] (1)Preparation of negatively charged silver particles

[0077] Dropwise add 5 ml of silver nitrate solution with a concentration of 60 mmol / L into 100 ml of sodium alginate aqueous solution with a pH of 13 and a concentration of 20 mg / mL, stir evenly to obtain a mixture, then dropwise add 5 ml of ascorbic acid solution with a concentration of 15 mg / L into the mixture, treat it at 900 W for 1.5 h at 90 °C, centrifuge to discard the supernatant, wash with distilled water, place the precipitate in a -80 °C refrigerator and freeze for 2 d, and then freeze-dry at -40 °C for 3 d to obtain sodium alginate silver nanoparticles;

[0078] (2) Preparation of hydroxylated negatively charged silver particles

[0079] Dissolve 10 g of sodium alginate silver nanoparticles in 50 ml of deionized water, then add 6 g of glycolic acid, and then add 10 ml of hydrochloric acid. Stir and react under dark conditions at 90 °C for 3 h. Then pour the obtained reaction mixture into ethanol for filtration, wash the precipitate with ethanol, and dry it at room temperature to obtain hydroxylated negatively charged silver particles;

[0080] (3) Preparation of negatively charged silver-polyphosphazene microspheres

[0081] Under a nitrogen atmosphere, disperse 5 g of hexachlorocyclotriphosphazene and 20 g of hydroxylated negatively charged silver particles in 30 ml of anhydrous acetonitrile. After stirring, add 2 g of triethylamine and heat and react at 100 °C for 24 hours. After the reaction, centrifuge to collect the product, wash it 5 times with acetonitrile and ethanol, and dry it under vacuum to obtain negatively charged silver-polyphosphazene microspheres;

[0082] (4) Preparation of solution A

[0083] Add 5 g of polyacrylamide to 50 ml of deionized water, stir at 90 °C for 4 h to obtain an aqueous polyacrylamide solution. Add 5 g of negatively charged silver-polyphosphazene microspheres to the aqueous polyacrylamide solution, stir evenly at 55 °C, add 8 g of aniline and 14 g of silicon nanoparticles with a diameter of 80 nm, and ultrasonically disperse evenly at room temperature to obtain solution A;

[0084] (5) Preparation of the negative electrode of a silicon lithium battery

[0085] Add 5 g of ammonium persulfate to 10 ml of deionized water to obtain an ammonium persulfate solution. Slowly pour the ammonium persulfate solution into solution A, stir the mixed solution to make it uniform, cool the mixed solution to 3 °C and polymerize for 6 h, and then keep it at room temperature for 24 h. Slowly wash the formed hydrogel with deionized water to obtain a negative electrode of a silicon lithium battery.

[0086] Comparative example 1

[0087] The present invention provides a method for preparing a negative electrode of a silicon lithium battery, and the steps are as follows:

[0088] (1) Preparation of solution A

[0089] Add 2 g of polyacrylamide to 50 ml of deionized water, stir at 60 °C for 2 h to obtain an aqueous polyacrylamide solution. Add 2 g of negatively charged silver-polyphosphazene microspheres to the aqueous polyacrylamide solution, stir evenly at 45 °C, add 3 g of aniline and 8 g of silicon nanoparticles with a diameter of 50 nm, and ultrasonically disperse evenly at room temperature to obtain Solution A;

[0090] (2) Preparation of the negative electrode of a silicon lithium battery

[0091] Add 3 g of ammonium persulfate to 10 ml of deionized water to obtain an ammonium persulfate solution. Slowly pour the ammonium persulfate solution into Solution A, stir the mixed solution to make it uniform, cool the mixed solution to 3 °C and polymerize for 4 h, then keep it at room temperature for 12 h. Slowly wash the formed hydrogel with deionized water until clean to obtain a negative electrode of a silicon lithium battery.

[0092] Prepare the negative electrode of a silicon lithium battery obtained in Examples 1-4 and Comparative Example 1 into a battery, and the steps are as follows:

[0093] Coat the negative electrode of the silicon lithium battery on a copper foil, press and cure it, and dry it at 50 °C for 24 h to obtain a negative electrode plate; use lithium cobaltate as the positive electrode plate and a polypropylene film as the separator. Assemble it into a battery cell according to the positive electrode-separator-negative electrode method with a battery cell diameter of 14 mm and a height of 50 mm. Then inject LiPF6 electrolyte into the battery cell to assemble a silicon-based lithium battery.

[0094] Perform performance tests on the silicon-based batteries prepared in the above Examples 1-4 and Comparative Example 1:

[0095] Electrochemical performance test method: Use a Wuhan Blue Electric CT2001A battery tester, with a charge-discharge voltage range of 0.005 V to 2.0 V and a charge-discharge rate of 0.1 C.

[0096] Specific surface area detection method: According to the national standard GB / T 19587-2004, use the gas adsorption BET method to measure the specific surface area of solid substances.

[0097] The test results are shown in Table 1 below:

[0098] Table 1

[0099] Negative electrode material Example 1 Example 2 Example 3 Example 4 Comparative Example 1 Initial discharge capacity (mAh / g) 501.43 500.53 502.21 503.98 199.65 <![CDATA[Specific surface area (m 2 / g)]]> 11.4 12.2 12.7 13.9 9.2

[0100] It can be seen from Table 1 of the above Examples 1-4 and Comparative Example 1 that the negative electrode material prepared by the present invention has good initial discharge capacity and specific surface area. In Comparative Example 1, after removing the negatively charged silver-polyphosphazene microspheres, the specific surface area of the negative electrode material decreased significantly, and the initial discharge capacity was also affected.

[0101] Cycling performance test:

[0102] The cycle performance of the battery was tested at a charge-discharge rate of 1C / 1C, a voltage range of 2.5V - 3.65V, and a temperature of 25 ± 3°C. The test results are shown in Table 2 as follows:

[0103] Table 2

[0104] Battery Capacity retention rate after 500 cycles (%) Example 1 90.98 Example 2 91.45 Example 3 91.09 Example 4 92.67 Comparative Example 1 72.6

[0105] As can be seen from Table 2, the cycle performance of the battery prepared from the anode of the silicon lithium battery of the present invention is significantly better than that of the comparative example. The possible reason is that: the silicon-based anode material prepared in the present invention has a certain tension and can accommodate the expansion change of the silicon-based material. At the same time, the introduction of negatively charged silver-polyphosphazene microspheres makes the dispersibility of the conductive agent polyaniline and silicon nanoparticles better, and the structure is more stable during the charge-discharge process, thus improving its cycle performance.

[0106] The above embodiments are only used to illustrate the technical solutions of the present invention and are not intended to limit them. Although the present invention has been described in detail with reference to the preferred embodiments, those of ordinary skill in the art should understand that the technical solutions of the present invention can be modified or equivalently replaced without departing from the spirit and scope of the technical solutions of the present invention, and they should all be covered within the scope of the claims of the present invention.

Claims

1. A silicon-lithium battery negative electrode, characterized in that, it is prepared from polyacrylamide, aniline, silicon nanoparticles, negatively charged silver-polyphosphazene microspheres and ammonium persulfate with a mass ratio of 2-5:2-8:8-14:2-5:3-5. The negatively charged silver-polyphosphazene microspheres are crosslinked by hexachlorocyclotriphosphazene and hydroxylated negatively charged silver particles under the catalysis of triethylamine. The silver particles in the hydroxylated negatively charged silver particles are prepared by in-situ reduction of silver nitrate in an aqueous sodium alginate solution. The diameter of the silicon nanoparticles is 50-80 nm; The preparation method of the silicon-lithium battery negative electrode includes the following steps: (1) Preparation of negatively charged silver particles Dropwise add a silver nitrate solution to an aqueous sodium alginate solution with a pH of 8-13, stir evenly to obtain a mixture, dropwise add an ascorbic acid solution to the mixture, ultrasonically treat the mixed system, centrifuge to discard the supernatant, wash with distilled water, place the precipitate in a -80 °C refrigerator and freeze for 1-2 d, and then freeze-dry at -40 °C for 1-3 d to obtain sodium alginate silver nanoparticles; (2) Preparation of hydroxylated negatively charged silver particles Dissolve the sodium alginate silver nanoparticles in deionized water, then add glycolic acid, and then add hydrochloric acid, stir until the reaction is complete, then pour the obtained reaction mixture into ethanol for filtration, wash the precipitate with ethanol, and dry at room temperature to obtain hydroxylated negatively charged silver particles; (3) Preparation of negatively charged silver-polyphosphazene microspheres Under a nitrogen atmosphere, disperse hexachlorocyclotriphosphazene and hydroxylated negatively charged silver particles in anhydrous acetonitrile, stir and then add triethylamine, heat the reaction, after the reaction is completed, centrifuge to collect the product, wash with acetonitrile and ethanol 3-5 times, and dry in vacuum to obtain negatively charged silver-polyphosphazene microspheres; (4) Preparation of solution A Add polyacrylamide to deionized water, stir to obtain an aqueous polyacrylamide solution, add negatively charged silver-polyphosphazene microspheres to the aqueous polyacrylamide solution, stir evenly at 45-55 °C, add aniline and silicon nanoparticles, and ultrasonically disperse evenly at room temperature to obtain solution A; (5) Preparation of the silicon-lithium battery negative electrode Add ammonium persulfate to deionized water to obtain an ammonium persulfate solution, slowly pour the ammonium persulfate solution into solution A, stir the mixed solution to make it uniform, polymerize the mixed solution at low temperature, and then keep it at room temperature for 12-24 h. Slowly wash the formed hydrogel with deionized water to obtain a silicon-lithium battery negative electrode.

2. A silicon-lithium battery negative electrode according to claim 1, characterized in that, in step (1), the volume ratio of the aqueous sodium alginate solution, the silver nitrate solution and the ascorbic acid solution is 100:1-5:1-5.

3. A silicon-lithium battery negative electrode according to claim 1, characterized in that, in step (1), the concentration of the aqueous sodium alginate solution is 10-20 mg / mL, the molar concentration of the silver nitrate solution is 40-60 mmol / L, the concentration of the ascorbic acid solution is 5-15 mg / L, and the ultrasonic condition is to treat at 15-90 °C with 100-900 W for 0.5-1.5 h.

4. A silicon-lithium battery negative electrode according to claim 1, characterized in that, In the step (2), the mass ratio of deionized water, sodium alginate silver nanoparticles, glycolic acid and hydrochloric acid is 30-50:5-10:3-6:5-10.

5. A silicon lithium battery negative electrode according to claim 1, wherein In the step (2), the reaction conditions are stirring reaction for 2-3 h under light avoidance at 70-90 °C.

6. A silicon lithium battery negative electrode according to claim 1, wherein In the step (3), the mass ratio of hexachlorocyclotriphosphazene, hydroxylated negatively charged silver particles and triethylamine is 15-25:100:1-2, and the reaction conditions are heating reaction for 12-24 hours at 90-100 °C.

7. A silicon lithium battery negative electrode according to claim 1, wherein In the step (4), the mass ratio of deionized water and polyacrylamide is 50:2-5, and the reaction conditions of deionized water and polyacrylamide are stirring for 2-4 h at 60-90 °C.

8. A silicon lithium battery, comprising the silicon lithium battery negative electrode according to any one of claims 1-7, wherein The preparation method of the silicon lithium battery comprises the following steps: (1) Coating the prepared silicon-based hydrogel on the negative electrode grid, and after pressurization and drying, preparing a silicon-based hydrogel negative electrode plate; (2) Selecting a conventional formula lithium battery positive electrode as the positive electrode plate of the battery, using a commercially available battery cell of corresponding size as the battery cell body, assembling it into the battery cell in the order of positive electrode - separator - negative electrode, and then injecting electrolyte into the battery cell body to assemble a silicon-based lithium battery.