High power low expansion silicon-oxygen metal oxide composite and method of making same

Abstract

The application relates to the technical field of lithium ion battery materials, and discloses a high-power low-expansion silicon-oxygen metal oxide composite material and a preparation method thereof, wherein porous metal is used as an inner core, nano silicon and carbon nanotubes are deposited on the surface of the porous metal through an electrochemical deposition method, drying is carried out, and finally, a fast ion composite conductor is deposited on the surface of the porous metal through an atomic vapor deposition method, so that a silicon-oxygen composite material is obtained. The silicon-oxygen composite material utilizes the fast ion conductor of the shell to improve the ion transmission rate in the charging and discharging process, utilizes the porous metal of the inner core to reduce expansion and improve electronic conductivity, simultaneously utilizes the network structure of the carbon nanotubes to bind the expansion of silicon, improve liquid retention, and improve cycle performance. The silicon-oxygen composite material prepared by the application has the characteristics of low expansion, good power performance, excellent cycle performance and the like when applied to a lithium ion battery.

Description

TECHNICAL FIELD

[0001] The present application relates to the technical field of lithium ion battery materials, in particular to a high-power low-expansion silicon-oxygen metal oxide composite material and a preparation method thereof. BACKGROUND

[0002] Silicon-oxygen materials have become the preferred negative electrode material for high-energy-density lithium ion batteries due to their high energy density, good cycle performance, low price, and other advantages. However, the electronic conductivity of silicon-oxygen materials is relatively poor, which affects the rate performance of the battery. In addition, the silicon-oxygen material itself has a large full-charge expansion, which causes the repeated expansion of the electrode during charging and discharging, resulting in the repeated repair of the SEI, consumption of lithium ions, and reduction of the cycle and storage performance. There are many methods to improve the electronic conductivity of the material and reduce the expansion, such as surface coating, reducing the reaction temperature to reduce the silicon grain size, preparing a porous core material and providing a buffer space, and reducing the expansion. However, the above measures can reduce the expansion and impedance, but they have poor uniformity and can cause deterioration of the storage and cycle performance, making it difficult to industrialize. SUMMARY

[0003] To improve the power performance and reduce the expansion of silicon-oxygen materials, the present application prepares a porous metal and deposits silicon-oxygen and carbon nanotubes on the surface thereof by electrochemical deposition, dries it, and finally deposits a fast-ion composite conductor on the surface thereof by atomic vapor deposition to obtain a fast-ion conductor-coated silicon-oxygen metal oxide composite material. This composite material has high electronic and ionic conductivity, improves the power performance, and the porous metal core buffers the expansion of silicon-oxygen during charging and discharging, improving the cycle performance.

[0004] The technical solution of the present application is: a high-power low-expansion silicon-oxygen metal oxide composite material, characterized in that: the composite material has a core-shell structure, the core is a porous metal, the middle layer is nano-silicon and carbon nanotubes, and the shell is a fast-ion composite conductor. The mass ratio of the core, the middle layer, and the shell is 10-30:30-60:1-10.

[0005] Another technical solution of the present application is: a preparation method of a high-power low-expansion silicon-oxygen metal oxide composite material, characterized in that it comprises the following steps:

[0006] 1) Electrochemical deposition is performed using a porous carbon as a substrate and as a cathode, a 0.1 mol / L metal chloride salt solution as a solvent, a metal rod as an anode, a constant current method, and an electric current density of 1-10 A / cm 2 2) After electrochemical deposition for 10-120 min, washing, vacuum drying, and transferring to a tube furnace, oxygen mixed gas is introduced for sintering to obtain a porous metal compound;

[0007] 2) using the electrochemical deposition method, taking the porous metal compound prepared in step 1) as a working electrode, a saturated mercury-mercury electrode as a reference electrode, and a silane coupling agent and carbon nanotube mixed solution as a solvent, using the cyclic voltammetry method, under the condition of -2V-2V voltage and 0.5-5mV / S scanning speed, and after 10-100 cycles, dilute hydrochloric acid washing and vacuum drying, carbonization at 800℃ for 1-6h, a silicon-oxygen and carbon nanotube loaded porous metal oxide is obtained;

[0008] 3) transferring the silicon-oxygen and carbon nanotube loaded porous metal oxide prepared in step 2) into a tube furnace, using the atomic vapor deposition method to deposit a fast ionic composite conductor, and then naturally cooling to room temperature, to obtain a fast ionic conductor coated silicon-oxygen metal oxide composite material.

[0009] Further, the metal chloride salt in the metal chloride salt solution in step 1) is selected from one of nickel chloride, copper chloride, cobalt chloride, manganese chloride and iron chloride; the metal rod is selected from one of a nickel rod, a copper rod, a cobalt rod, a manganese rod and an iron rod, and the purity of the metal rod is ≥99%.

[0010] Further, the preparation method of the silane coupling agent and carbon nanotube mixed solution in step 2) is that 1-10 parts of a silane coupling agent and 1-10 parts of carbon nanotubes are weighed and added into 500 parts of N-methyl pyrrolidone, and then ultrasonic dispersion is performed until uniform, and then 0.1-1 parts of lithium difluoroborate is added and ultrasonic dispersion is performed until uniform, to obtain the mixed solution.

[0011] Further, the silane coupling agent is selected from one of γ-chloropropyltrimethoxysilane, vinyltrichlorosilane, vinyltriethoxysilane, vinyltris(2-methoxyethoxy)silane and γ-methacryloyloxypropyltrimethoxysilane.

[0012] Further, the fast ionic composite conductor in step 3) is an organic fast ionic composite conductor, and the preparation method of the fast ionic composite conductor is that an organic lithium salt, a binder and a conductive agent are mixed uniformly, the mass ratio of the organic lithium salt, the binder and the conductive agent is 10:1-2:1-2, and hot pressing is performed at 25-100℃, to obtain the fast ionic composite conductor.

[0013] Further, the organic lithium salt is a lithium sulfonylimide salt or lithium difluoro(oxalato)borate; the binder is selected from one of polymethyl methacrylate, polyacrylate, polyvinyl alcohol and polyvinylidene fluoride; and the conductive agent is selected from one of polyaniline, polythiophene and polypyrrole.

[0014] The beneficial effects of the application are as follows:

[0015] 1) The porous metal compound is prepared, and a silicon-based material is deposited on the surface thereof by an electrochemical deposition method, which has the advantages of high deposition density, uniform deposition, high efficiency, etc. The porous metal compound prepared by the present application has the characteristics of high electronic conductivity, thereby improving the rate performance.

[0016] 2) The fast ion composite conductor is deposited by an atomic vapor deposition method, which relies on the characteristics of high electronic conductivity of the fast ion conductor to improve the fast charging performance, and combines the characteristics of high electronic conductivity of the carbon nanotube, so that the shell fast ion conductor and the carbon nanotube can synergistically improve the fast charging performance. BRIEF DESCRIPTION OF DRAWINGS

[0017] Figure 1 FIG. 1 is an SEM image of a fast ion conductor coated silicon-oxygen metal oxide composite material prepared in Example 1. DETAILED DESCRIPTION

[0018] Example 1

[0019] A preparation method of a high-power low-expansion silicon-oxygen metal oxide composite material, comprising the following steps:

[0020] 1) A porous carbon is used as a substrate and as a cathode, a 0.1 mol / L nickel chloride solution is used as a solvent, a nickel rod is used as an anode, and a constant current method (current density: 5 A / cm 2 ) is used to perform electrochemical deposition for 60 min, then washed, vacuum dried at 80°C for 24 h, then transferred to a tube furnace, and an oxygen mixed gas (volume ratio, oxygen: argon = 1:10) is introduced to perform 800°C sintering for 3 h, to obtain a porous metal compound;

[0021] 2) The porous metal compound prepared in step 1) is used as a working electrode, a saturated mercury-mercury electrode is used as a reference electrode, a silane coupling agent and a carbon nanotube mixed solution are used as a solvent, and a cyclic voltammetry method is used to perform cyclic voltammetry for 10 weeks under the condition of a voltage of -2V-2V and a scanning speed of 0.5 mV / S, then washed with dilute hydrochloric acid, vacuum dried at 80°C for 24 h, and carbonized at 800°C for 3 h, to obtain a silicon-oxygen and carbon nanotube loaded porous metal oxide;

[0022] 3) The silicon-oxygen and carbon nanotube loaded porous metal oxide prepared in step 2) is transferred to a tube furnace, and a lithium sulfonimide composite conductor is deposited by an atomic vapor deposition method, then naturally cooled to room temperature, to obtain a fast ion conductor coated silicon-oxygen metal oxide composite material (referred to as: silicon-carbon composite material).

[0023] The preparation method of the silane coupling agent and carbon nanotube mixed solution in step 2) is as follows: 5 g of γ-chloropropyltrimethoxysilane and 5 g of carbon nanotubes are weighed respectively and added into 500 g of N-methylpyrrolidone, and then ultrasonic dispersion is performed until uniform, after which 0.5 g of lithium difluoroborate is added and ultrasonic dispersion is performed until uniform, to obtain the silane coupling agent and carbon nanotube mixed solution.

[0024] The preparation method of the lithium sulfonimide salt composite conductor in step 3) is as follows: 10 g of lithium sulfonimide salt, 2 g of polyvinyl alcohol, and 2 g of polyaniline are weighed respectively and mixed uniformly, and then hot pressing is performed at a temperature of 60°C for 1 h to obtain the lithium sulfonimide salt composite conductor.

[0025] The atomic vapor deposition method in step 3) is as follows: the lithium sulfonimide salt composite conductor is used as the target material, the vacuum chamber is evacuated and kept at a pressure of 0.1 Torr, the temperature is raised to 500°C, and the lithium sulfonimide salt composite conductor and the oxygen source are introduced into the reaction chamber for cyclic deposition. The set program for cyclic deposition is as follows: the lithium sulfonimide salt composite conductor is introduced for 0.5 seconds, nitrogen is blown for 60 seconds, the oxygen source is introduced for 5 seconds, nitrogen is blown for 5 seconds, water is introduced for 0.05 seconds, and nitrogen is blown for 50 seconds. The cyclic deposition is performed for 50 cycles starting from the introduction of the lithium sulfonimide salt composite conductor for 0.5 seconds.

[0026] Example 2:

[0027] A preparation method of a high-power low-expansion silicon-oxygen metal oxide composite material, comprising the following steps:

[0028] 1) A porous metal compound is obtained by the following steps: an electrochemical deposition method is used, porous carbon is used as the substrate and as the cathode, a 0.1 mol / L copper chloride solution is used as the solvent, a copper rod is used as the anode, and then a constant current method (current density: 1 A / cm 2 ) is used for electrochemical deposition for 10 min, and then washing, vacuum drying at 80°C for 24 h, and then transferring into a tube furnace and introducing oxygen mixed gas (volume ratio, oxygen: argon = 1:10) for 800°C sintering for 3 h.

[0029] 2) A silicon-oxygen and carbon nanotube supported porous metal oxide is obtained by the following steps: an electrochemical deposition method is used, the porous metal compound prepared in step 1) is used as the working electrode, a saturated calomel electrode is used as the reference electrode, the silane coupling agent and carbon nanotube mixed solution is used as the solvent, and then a cyclic voltammetry method is used, the voltage is -2V-2V, the scanning speed is 0.5 mV / S, and the cyclic deposition is performed for 10 cycles, and then dilute hydrochloric acid washing, vacuum drying at 80°C for 24 h, and 800°C carbonization for 1 h.

[0030] 3) The silicon oxide and carbon nanotube loaded porous metal oxide prepared in step 2) is transferred into a tube furnace, and a lithium bis (fluorosulfonyl) borate composite conductor is deposited by atomic vapor deposition, and then naturally cooled to room temperature to obtain a fast ionic conductor coated silicon oxide metal oxide composite (referred to as: silicon-carbon composite material).

[0031] The preparation method of the silane coupling agent and carbon nanotube mixed solution in step 2) is as follows: 1 g of vinyltrichlorosilane and 1 g of carbon nanotubes are weighed and added to 500 g of N-methylpyrrolidone, and ultrasonic dispersion is performed until uniform, then 0.1 g of lithium difluoroborate is added and ultrasonic dispersion is performed until uniform, to obtain a silane coupling agent and carbon nanotube mixed solution (vinyltrichlorosilane and carbon nanotube mixed solution).

[0032] The preparation method of the lithium bis (fluorosulfonyl) borate composite conductor in step 3) is as follows: 10 g of lithium bis (fluorosulfonyl) borate, 1 g of polyvinylidene fluoride, and 1 g of polythiophene are weighed and mixed uniformly, and hot-pressed at a temperature of 25°C for 2 h to obtain a lithium bis (fluorosulfonyl) borate composite conductor.

[0033] The atomic vapor deposition method in step 3) is as follows: the lithium bis (fluorosulfonyl) borate composite conductor is used as the target material, the vacuum chamber is evacuated and maintained at a pressure of 0.1 Torr, the temperature is raised to 500°C, and the lithium bis (fluorosulfonyl) borate composite conductor and the oxygen source are introduced into the reaction chamber for cyclic deposition. The cyclic deposition program is set as follows: introduction of the lithium bis (fluorosulfonyl) borate composite conductor for 0.5 seconds, nitrogen purging for 60 seconds, introduction of the oxygen source for 5 seconds, nitrogen purging for 5 seconds, introduction of water for 0.05 seconds, and nitrogen purging for 50 seconds. The cyclic deposition is performed for 10 cycles starting from the introduction of the lithium bis (fluorosulfonyl) borate composite conductor for 0.5 seconds.

[0034] Example 3:

[0035] A method for preparing a high-power low-expansion silicon oxide metal oxide composite material, comprising the following steps:

[0036] 1) A porous carbon is used as the substrate and as the cathode, a 0.1 mol / L iron chloride solution is used as the solvent, and a metal iron is used as the anode, and then a constant current method (current density: 10 A / cm 2 ) is used for electrochemical deposition for 120 min, and then washed and vacuum dried at 80°C for 24 h, and then transferred into a tube furnace and introduced into an oxygen mixed gas (volume ratio, oxygen: argon = 1:10) for sintering at 800°C for 3 h to obtain a porous metal compound.

[0037] 2) Electrochemical deposition method, porous metal compound prepared in step 1) as working electrode, saturated calomel electrode as reference electrode, silane coupling agent and carbon nanotube mixed solution as solvent, and cyclic voltammetry method, under the condition of-2V-2V voltage, scanning speed is 5mV / S, cycle 100 times, then dilute hydrochloric acid washing, 80℃ vacuum drying 24h, 800℃ carbonization 1h, get silicon and carbon nanotube loaded porous metal oxide;

[0038] 3) The silicon and carbon nanotube loaded porous metal oxide prepared in step 2) is transferred to a tube furnace, and atomic vapor deposition method is used to deposit lithium difluoro(oxalato)borate composite conductor, and then naturally cooled to room temperature to obtain a fast ion conductor coated silicon metal oxide composite material (referred to as: silicon carbon composite material).

[0039] The preparation method of the silane coupling agent and carbon nanotube mixed solution in step 2) is as follows: 10g of vinyl tri(2-methoxyethoxy) silane and 1g of carbon nanotube are weighed and added into 500 parts of N-methyl pyrrolidone, and ultrasonic dispersion is uniform, then 1g of lithium difluoroborate is added and ultrasonic dispersion is uniform, to obtain a silane coupling agent and carbon nanotube mixed solution.

[0040] The preparation method of the lithium difluoro(oxalato)borate composite conductor in step 3) is as follows: 10g of lithium difluoro(oxalato)borate, 1g of polymethyl methacrylate and 1g of polypyrrole are mixed uniformly, and hot pressing is carried out at a temperature of 100℃ for 0.5h to obtain a lithium difluoro(oxalato)borate composite conductor.

[0041] The atomic vapor deposition method in step 3) is as follows: the lithium difluoro(oxalato)borate composite conductor is used as the target material, the vacuum chamber is evacuated and kept at a pressure of 0.1 Torr, the temperature is raised to 500℃, and the lithium difluoro(oxalato)borate composite conductor and the oxygen source are introduced into the reaction chamber for cyclic deposition. The setting program for cyclic deposition is as follows: introduction of lithium difluoro(oxalato)borate composite conductor for 0.5 seconds, nitrogen blowing for 60 seconds, introduction of oxygen source for 5 seconds, nitrogen blowing for 5 seconds, introduction of water for 0.05 seconds, and nitrogen blowing for 50 seconds. The cyclic deposition is started from the introduction of lithium difluoro(oxalato)borate composite conductor for 0.5 seconds and is repeated for 100 cycles.

[0042] Comparative Example 1:

[0043] A preparation method of a fast ion conductor / silicon-based / carbon nanotube coated metal oxide material, comprising the following steps:

[0044] 1) Electrochemical deposition method, nickel rod as working electrode, the rest same as example 1 step 2), get silicon and carbon nanotube loaded metal oxide;

[0045] 2) Transfer the silicon oxide and carbon nanotube-loaded metal oxide prepared in step 1) to a tube furnace, and repeat the same steps as in Example 1, step 3), to obtain a fast ion conductor / silicon-based / carbon nanotube-coated metal oxide material.

[0046] Comparative Example 2:

[0047] Take 100 mL of the vinyltrichlorosilane and carbon nanotube mixture prepared in Example 2, add 10 g of nickel chloride and disperse evenly, then filter, vacuum dry at 80 °C for 24 h, then transfer to a tube furnace, introduce methane gas to remove air from the tube, and carbonize at 800 °C for 1 h, then pulverize to obtain silicon-carbon composite material.

[0048] Test Experiment 1

[0049] 1. Physicochemical tests

[0050] (1) Morphological test

[0051] The silicon-carbon composite material prepared in Example 1 was subjected to SEM testing, and the test results are as follows: Figure 1 As shown. By Figure 1 It can be seen that the material has a granular structure, and the particle size distribution is uniform and reasonable. There are amorphous carbon materials between the particles, and the particle size is between 2-8μm.

[0052] (2) The specific surface area, tap density and carbon content of silicon-based composite materials were tested in accordance with GB / T 38823-2020 "Silicon Carbon", and the electrical conductivity of silicon carbon composite materials was tested using a four-probe tester.

[0053] (3) Full charge expansion: Test the thickness D1 of the negative electrode sheet of the coin cell after rolling, then dissect the full charge thickness D2 of the negative electrode sheet when the coin cell is fully charged to 100% SOC, and then calculate the expansion rate (expansion rate = (D2-D1) / D1*100%).

[0054] The test results are shown in Table 1.

[0055] 2. Electrochemical performance testing

[0056] (1) Button cell test

[0057] The silicon-carbon composite materials used in Examples 1-3 and Comparative Examples 1-2 were used as negative electrode materials for lithium-ion batteries to prepare coin cells according to the following method:

[0058] The binder, the conductive agent and the solvent are added to the silicon-carbon composite material, and stirring is carried out to prepare a slurry, which is coated on a copper foil, and then dried and rolled to obtain a negative electrode sheet; the binder is polyvinylidene fluoride (PVDF), the conductive agent is conductive carbon black (SP), and the solvent is N-methyl pyrrolidone (NMP), wherein the amount ratio of the silicon-carbon composite material, SP, PVDF and NMP is 95g:1g:4g:220mL; the electrolyte is a solution of lithium hexafluorophosphate (LiPF6) as an electrolyte, and the concentration is 1mol / L, wherein the solvent is a mixture of ethylene carbonate (EC) and diethyl carbonate (DEC) in a volume ratio of 1:1; lithium metal is used as a counter electrode, and a polypropylene (PP) film is used as a separator. The button cell is assembled in an argon-filled glove box.

[0059] The electrochemical performance is tested on a Wuhan Lan Electric CT2001A battery tester, and the charge and discharge voltage range is 0.005V to 2.0V, and the charge and discharge rate is 0.1C.

[0060] The test results are shown in Table 1.

[0061] Table 1

[0062]

[0063] As can be seen from the data in Table 1, the specific capacity and the first efficiency of the silicon-carbon composite material prepared by the application are obviously better than those of the comparative examples. The reason is that: the silicon-oxygen material is deposited by an electrochemical deposition method, which has the advantages of high density, reduced impedance, reduced material defect degree to improve the first efficiency, and the porous structure of the porous metal material has the advantages of high specific surface area and high electronic conductivity of the material; and the expansion of the material is reduced.

[0064] Test experiment two

[0065] The silicon-carbon composite materials of Examples 1-3 and Comparative Examples 1-2 are respectively doped with 90% artificial graphite as a negative electrode material, and assembled into 5Ah soft package batteries with positive electrode ternary material (LiNi 1 / 3 Co 1 / 3 Mn 1 / 3 O2), electrolyte and separator. The separator is celegard 2400, and the electrolyte is a LiPF6 solution (the solvent is a mixed solution of EC and DEC in a volume ratio of 1:1, and the concentration of LiPF6 is 1.3mol / L). The prepared soft package batteries (lithium ion batteries) are respectively marked as A-2, B-2, C-2, D-2 and E-2.

[0066] The soft package batteries are subjected to the following performance tests:

[0067] 1. Liquid absorption capacity test

[0068] Using a 1 mL burette, and taking electrolyte V mL, dropping one drop on the surface of the pole piece, and timing until the electrolyte is absorbed, recording the time t, and calculating the liquid absorption rate of the pole piece V / t. The test results are shown in Table 2.

[0069] 2. Liquid retention rate test

[0070] According to the pole piece parameters, the theoretical liquid absorption amount of the pole piece mL is calculated, and the weight of the pole piece m2 is weighed, then the pole piece is placed in the electrolyte for 24 h, the weight of the pole piece is weighed as m3, the liquid absorption amount of the pole piece m3-m2 is calculated, and the liquid retention rate is calculated according to the following formula: liquid retention rate = (m3-m2)*100% / mL. The test results are shown in Table 2.

[0071] Table 2

[0072] Suction rate (mL / min) Liquid retention Example 1 5.4 90.1％ Example 2 5.9 91.2％ Example 3 4.5 89.4％ Comparative Example 1 2.5 84.9％ Comparative Example 2 1.5 82.7％

[0073] As can be seen from Table 2, the liquid absorption and retention capacity of the silicon-carbon composite material prepared in Examples 1-3 is obviously higher than that of the comparative examples. The reason is that the specific surface area of the silicon-carbon composite material prepared in Examples 1-3 is larger, which improves the liquid absorption and retention capacity of the material.

[0074] 3. Rate and cycle performance

[0075] The cycle performance test and rate test are carried out on the soft pack batteries A-2 to E-2. The cycle test conditions are: the charge and discharge voltage range is 2.5-4.2 V, the temperature is 25±3.0℃, the charge and discharge rate is 0.5C / 1.0C, and the cycle number is 500 times. The rate test conditions are: the constant current ratio of the material under 2C condition is tested, then the 100% SOC of the charged battery is dissected and analyzed, and the full charge rebound of the pole piece before the test is tested. The test results are shown in Table 3.

[0076] Table 3

[0077]

[0078] As can be seen from Table 3, the cycle performance of the soft pack lithium ion battery prepared by using the silicon-carbon composite material of the application is better than that of the comparative examples, and the reason is that the silicon-carbon material of the application is electrochemically deposited on the porous metal to reduce the expansion and has a higher specific surface area, which improves the liquid retention performance of the material and improves the cycle performance; at the same time, the silicon-carbon composite material of the application is doped with a metal compound with high electronic conductivity to reduce the impedance and improve the rate performance (constant current ratio); at the same time, the application uses a porous metal as a substrate to deposit a silicon-based material on the surface of the substrate to reduce the expansion.

[0079] The above-described embodiments are only the preferred schemes of the application, and do not limit the application in any form, and other variants and modifications can be made without exceeding the technical scheme recited in the claims.

Claims

1. A high power low expansion silicon-oxygen-metal oxide composite, characterized by: The composite material presents a core-shell structure, the inner core is a porous metal, the intermediate layer is nano silicon and carbon nanotubes, and the shell is a fast ion composite conductor, and the mass ratio of the inner core, the intermediate layer and the shell is 10-30:30-60:1-10. The preparation method of the composite material comprises the following steps: 1) using electrochemical deposition method, taking porous carbon as matrix and as cathode, 0.1 mol / L metal chloride salt solution as solvent, metal rod as anode, using constant current method, current density is 1-10 A / cm 2 , electrochemical deposition for 10-120 min, then washing, vacuum drying, and transferring to tube furnace, sintering by passing oxygen mixed gas, to obtain porous metal compound; 2) using the porous metal compound prepared in step 1) as a working electrode, a saturated mercury-mercury electrode as a reference electrode, and a silane coupling agent and carbon nanotube mixed solution as a solvent, a cyclic voltammetry method is used to scan at a voltage of-2V-2V and a scanning speed of 0.5-5mV / S for 10-100 cycles, and then the prepared product is washed with dilute hydrochloric acid, vacuum dried, and carbonized at 800℃ for 1-6h to obtain a silicon-oxygen and carbon nanotube loaded porous metal oxide; the preparation method of the silane coupling agent and carbon nanotube mixed solution is as follows: 1-10 parts of a silane coupling agent and 1-10 parts of carbon nanotubes are weighed and added to 500 parts of N-methyl pyrrolidone, ultrasonic dispersion is performed until they are uniformly dispersed, then 0.1-1 parts of lithium difluoroborate is added and ultrasonic dispersion is performed until it is uniformly dispersed, and a mixed solution is obtained; 3) the silicon-oxygen and carbon nanotube loaded porous metal oxide prepared in step 2) is transferred into a tube furnace, an atomic vapor deposition method is used to deposit a fast ion composite conductor, and then the prepared product is naturally cooled to room temperature to obtain a fast ion conductor coated silicon-oxygen metal oxide composite material.

2. The method for preparing the high-power, low-expansion silicon-oxygen metal oxide composite material according to claim 1, characterized in that: The metal chloride salt in the metal chloride salt solution in step 1) is selected from one of nickel chloride, copper chloride, cobalt chloride, manganese chloride and iron chloride; the metal rod is selected from one of a nickel rod, a copper rod, a cobalt rod, a manganese rod and an iron rod, and the purity of the metal rod is greater than or equal to 99%.

3. The method for preparing the high-power, low-expansion silicon-oxygen metal oxide composite material according to claim 1, characterized in that: The silane coupling agent is selected from one of γ-chloropropyltrimethoxysilane, vinyltrichlorosilane, vinyltriethoxysilane, vinyltri(2-methoxyethoxy)silane and γ-methacryloyloxypropyltrimethoxysilane.

4. The method for preparing the high-power, low-expansion silicon-oxygen metal oxide composite material according to claim 1, characterized in that: The fast ion composite conductor in step 3) is an organic fast ion composite conductor, and the preparation method of the fast ion composite conductor is as follows: an organic lithium salt, a binder and a conductive agent are uniformly mixed, the mass ratio of the organic lithium salt, the binder and the conductive agent is 10:1-2:1-2, and hot pressing is performed at 25-100℃ to obtain the fast ion composite conductor.

5. The method for preparing the high-power, low-expansion silicon-oxygen metal oxide composite material according to claim 4, characterized in that: The organic lithium salt is a lithium sulfonylimide salt or lithium difluoro(oxalato)borate; the binder is selected from one of polyacrylate, polyvinyl alcohol and polyvinylidene fluoride; and the conductive agent is selected from one of polyaniline, polythiophene and polypyrrole.

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