CN113363473B - Preparation method of high-first-efficiency SiO graphite composite negative electrode material - Google Patents
Preparation method of high-first-efficiency SiO graphite composite negative electrode material Download PDFInfo
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Abstract
The invention relates to the technical field of battery preparation, and provides a preparation method of a high-efficiency SiO graphite composite negative electrode material aiming at the problem that the SiO material and graphite are difficult to uniformly mix, which comprises the following steps: 1) uniformly mixing SiO, graphite, an organic carbon source and Li salt to obtain a mixture A, wherein the particle size of the SiO is smaller than that of the graphite; 2) granulating the mixture A to obtain a precursor B of the SiO/graphite composite material; 3) and calcining the composite material precursor B at high temperature in the atmosphere of inert gas, and naturally cooling to room temperature to obtain the carbon-coated SiO/graphite composite negative electrode material. SiO is inlaid between graphite and bonded together through a carbon source, the problems of volume expansion and pulverization of the SiO are effectively limited through the outer-layer graphite, and the first coulombic efficiency and the cycling stability of the negative electrode material are greatly improved through Li salt. Meanwhile, the method has simple preparation process and low cost and is beneficial to mass production.
Description
Technical Field
The invention relates to the technical field of battery preparation, in particular to a preparation method of a high-first-efficiency SiO graphite composite negative electrode material.
Background
The negative electrode material of the lithium battery is one of the key factors determining the charge-discharge efficiency, the cycle life and other performances of the lithium battery. At present, the commercial lithium battery mainly uses graphite as a negative electrode material, and the specific capacity of a high-end graphite material in the market reaches 360-365mAh/g, which is close to the theoretical specific capacity (372mAh/g) of graphite, so that the promotion space of the energy density of the lithium battery using graphite as the negative electrode material is limited, and the requirement of the high energy density of the power battery cannot be met. The SiO material has high capacity (2600mAh/g), volume change in the cycle process is smaller than that of the Si material, lithium oxide and lithium silicate which are irreversibly formed in the first charge-discharge process can play a buffering role in the cycle process, and the cycle performance is better than that of the Si material, so that the SiO material becomes a commercial graphite cathodeOne of the alternatives of (a). But the SiO material can generate larger volume expansion in the process of lithium embedding, a conductive network is damaged, and the material is easy to pulverize in the circulating process, so that the capacity of the battery is quickly attenuated; the inherent conductivity of SiO is far lower than that of graphite, and serious electrode polarization can be generated during large-current charging and discharging; in the charge and discharge process, Li is continuously consumed due to the generation of a solid electrolyte interface film (SEI)+Resulting in reduced coulombic efficiency. Compared with graphite, the SiO material as a negative electrode material is obviously lower, and the capacity of the battery cell is not obviously increased.
The SiO material and the graphite are simply mixed together and are difficult to disperse uniformly in the process of preparing the pole piece, so that the SiO material and the graphite are effectively combined together to form the composite material, the problem of volume expansion and pole piece distribution can be effectively solved, and the composite material is expected to become one of the first choices of the next generation of high-energy density battery cathode material. For example, patent CN 109037636 a proposes a new method, which comprises the following steps: 1) weighing SiO and a sand grinding medium according to the mass ratio of (1-5) to (10), placing the SiO and the sand grinding medium in a sand mill tank, adding a grinding aid, mixing, then carrying out sand grinding to nano SiO to obtain SiO suspension liquid 2), dispersing the suspension liquid of SiO and an inorganic carbon source uniformly, and then carrying out spray drying granulation to obtain SiO powder coated by the carbon source; 3) placing the SiO powder coated with the carbon source in a tubular furnace, calcining at high temperature in the atmosphere of inert gas, and naturally cooling to room temperature to obtain a SiO/carbon composite material; 4) weighing the SiO/carbon composite material and graphite according to the mass ratio of 10:100, adding a ball milling medium for ball milling, uniformly mixing the SiO/carbon composite material and the graphite, and taking out to obtain the SiO/carbon/graphite composite negative electrode material. However, the preparation process of the nano SiO is complex, the cost is high, the commercialization is not facilitated, the nano SiO is adhered together to form large particles through spray drying, the nano effect cannot be achieved, and huge stress is still generated in the expansion process. Finally, the graphite and SiO composite material realized by the ball milling method has weak bonding force because the particles are physically polymerized together, and can be easily separated in the circulating process, so that the effect of relieving volume expansion cannot be realized. Accordingly, an ideal solution is needed.
Disclosure of Invention
The invention provides a preparation method of a high-first-efficiency SiO graphite composite negative electrode material, aiming at overcoming the problem that the SiO material and graphite are difficult to uniformly disperse in a mixed mode, SiO is embedded between the graphite and is bonded together through a carbon source, the problems of volume expansion and pulverization of the SiO are effectively limited through the graphite on the outer layer, and the first coulombic efficiency and the cycle stability of the negative electrode material are greatly improved through Li salt. Meanwhile, the method has simple preparation process and low cost and is beneficial to mass production.
In order to achieve the purpose, the invention adopts the following technical scheme:
a preparation method of a high-first-efficiency SiO graphite composite negative electrode material comprises the following steps:
(1) uniformly mixing SiO, graphite, an organic carbon source and Li salt according to the mass ratio of 1 (1-10) to 0.3-5 to 0.01-1 to obtain a mixture A, wherein the grain diameter of the SiO is smaller than that of the graphite;
(2) transferring the mixture A to granulation equipment for granulation in an inert gas atmosphere to obtain a SiO/graphite composite material precursor B;
(3) and calcining the composite material precursor B at high temperature in the atmosphere of inert gas, and naturally cooling to room temperature to obtain the carbon-coated SiO/graphite composite negative electrode material.
The preparation method of the SiO/carbon/graphite composite material provided by the invention comprises the steps of firstly, uniformly mixing SiO with a carbon source and Li salt, heating to melt the carbon source, and enabling SiO particles and the Li salt to react and be uniformly dispersed in the carbon source; then compounding with graphite and carrying out high-temperature carbonization treatment, so that the carbon source is re-melted to bond the SiO particles on the surfaces of the graphite particles. The surfaces of SiO and graphite are coated by carbon layers, and because the particle size of SiO is smaller than that of graphite, SiO is uniformly dispersed among the graphite in the granulation process to form a structure of sandwiching SiO between the graphite and the graphite, and the problems of volume expansion and pulverization of the SiO are effectively limited by the graphite at the outer layer. The method has the advantages of simple preparation process, low cost and good reproducibility, and is suitable for large-scale commercial production.
Preferably, the particle size of the SiO in step (1) is 0.5 to 5 μm.
Preferably, the organic carbon source in step (1) is one or more of glucose, citric acid, asphalt, polyvinylpyrrolidone, polyethylene glycol, sucrose, polyvinyl alcohol, polyacrylic acid, polyvinyl chloride and phenolic resin.
Preferably, the organic carbon source is citric acid, and the citric acid is subjected to modification treatment, specifically comprising the following steps:
1) dispersing citric acid in deionized water, adding titanium dioxide under stirring to ensure that the mass concentration of the titanium dioxide in the system is 180-300g/L and the mass of the citric acid is 0.05-0.1 percent of that of the titanium dioxide, performing wet ball milling for 20-30min, and drying to obtain the titanium dioxide grafted citric acid;
2) respectively dissolving titanium dioxide grafted citric acid and polyethylene oxide in dimethyl sulfoxide to prepare solutions, dropwise adding a titanium dioxide grafted citric acid solution into a polyethylene oxide solution according to the molar ratio (3-7) of the citric acid to the polyethylene oxide solution of 10, heating and stirring at 60-100 ℃ for reaction for 3-5h, cooling the reaction solution, dropwise adding the reaction solution into an ethanol solution of NaOH, separating out a solid, washing the solid, and drying to obtain the modified citric acid.
The organic carbon source bonds and fixes SiO in the graphite interlayer, and the invention modifies the organic carbon source citric acid: the citric acid contains hydroxyl and a plurality of carboxyl, the carboxyl of the citric acid reacts with the hydroxyl on the surface of the titanium dioxide to graft the titanium dioxide on the citric acid, and a large amount of hydroxyl on the surface of the titanium dioxide is beneficial to generating hydrogen bonds with SiO and graphite, so that the bonding property of an organic carbon source is improved, and the crushing of the SiO is effectively inhibited. Compared with the titanium dioxide particles directly added and compounded, the grafted titanium dioxide has better dispersity and stability. And reacting citric acid with polyoxyethylene to generate a cross-linked network structure, so as to form a protective layer and separate SiO from the electrolyte. And the citric acid can improve the mechanical property of the polyoxyethylene after reacting with the polyoxyethylene, and the citric acid plays a supporting role and can inhibit the volume expansion of SiO.
Preferably, the Li salt in the step (1) is one or more of LiH, LiOH and n-butyllithium.
Preferably, the graphite in the step (1) is one or more of artificial graphite, natural graphite and expanded graphite.
Preferably, the granulating equipment in the step (2) is one of a spray granulator, a VC coating machine, a vertical granulating kettle and a horizontal granulating kettle.
Preferably, the granulation process in step (2) is as follows: heating to 200-500 ℃ at the rate of 3-10 ℃/min, and preserving the heat for 30-60min, and then heating to 600-800 ℃ at the rate of 3-10 ℃/min, and preserving the heat for 1-3 h.
Preferably, the high-temperature calcination in step (3) is carried out by: heating to 800-.
Preferably, the inert gas comprises one or more of helium, argon and nitrogen.
Therefore, the invention has the following beneficial effects: (1) SiO is uniformly dispersed among the graphite in the granulation process to form a structure of sandwiching SiO between the graphite, and the problems of volume expansion and pulverization of the SiO are effectively limited by the graphite on the outer layer; (2) the modification of organic carbon source citric acid further limits the problems of volume expansion and pulverization of SiO; (3) the addition of the Li salt greatly improves the first coulombic efficiency and the cycling stability of the cathode material; (3) the method has the advantages of simple preparation process, low cost and good reproducibility, and is suitable for large-scale commercial production.
Detailed Description
The technical solution of the present invention is further illustrated by the following specific examples.
In the present invention, unless otherwise specified, all the raw materials and equipment used are commercially available or commonly used in the art, and the methods in the examples are conventional in the art unless otherwise specified.
Example 1
A preparation method of a high-first-efficiency SiO graphite composite negative electrode material comprises the following steps:
(1) taking SiO, artificial graphite, asphalt and LiH according to the mass ratio of 1:7:0.5:0.2, respectively, sucking the materials into a VC mixer through a vacuumizing pipeline, quickly stirring for 30 minutes, and stopping the machine after the four materials are effectively mixed; wherein the grain diameter of SiO is 0.5 μm, and the grain diameter of artificial graphite is 8 μm;
(2) transferring the mixed material to a vertical granulation kettle through vacuum equipment, introducing helium gas, stirring at the speed of 100 revolutions per minute, heating to 300 ℃ at the heating rate of 3 ℃/min, preserving heat for 1 hour, heating to 700 ℃ at the heating rate of 5 ℃/min, preserving heat for 2 hours, and naturally cooling to obtain a carbon source coated and bonded graphite/SiO composite material B;
(3) transferring the composite material B into a box furnace, heating to 900 ℃ at the heating rate of 5 ℃/min, preserving the heat for 2 hours, and then naturally cooling to obtain the SiO/graphite composite negative electrode material.
Example 2
A preparation method of a high-first-efficiency SiO graphite composite negative electrode material comprises the following steps:
(1) taking SiO, artificial graphite, asphalt and LiH according to the mass ratio of 1:7:0.5:0.1, respectively, sucking the materials into a VC mixer through a vacuumizing pipeline, quickly stirring for 30 minutes, and stopping the machine after the four materials are effectively mixed; wherein the grain diameter of SiO is 3 μm, and the grain diameter of artificial graphite is 10 μm;
(2) transferring the mixed material to a vertical granulating kettle through vacuum equipment, introducing argon, stirring at the speed of 100 revolutions per minute, heating to 300 ℃ at the heating rate of 3 ℃/min, preserving heat for 1 hour, heating to 700 ℃ at the heating rate of 5 ℃/min, preserving heat for 2 hours, and naturally cooling to obtain a carbon source coated and bonded graphite/SiO composite material B;
(3) transferring the composite material B into a box furnace, heating to 1000 ℃ at the heating rate of 5 ℃/min, preserving the heat for 2 hours, and then naturally cooling to obtain the SiO/graphite composite negative electrode material.
Example 3
A preparation method of a high-first-efficiency SiO graphite composite negative electrode material comprises the following steps:
(1) taking SiO, natural graphite, phenolic resin and n-butyl lithium according to the mass ratio of 1:6:0.7:0.3, respectively, sucking the materials into a VC mixer through a vacuumizing pipeline, quickly stirring for 30 minutes, and stopping the machine after the four materials are effectively mixed; wherein the grain diameter of SiO is 5 μm, and the grain diameter of artificial graphite is 15 μm;
(2) transferring the mixed material to a vertical granulation kettle through vacuum equipment, introducing nitrogen, stirring at the speed of 100 revolutions per minute, heating to 300 ℃ at the heating rate of 3 ℃/min, preserving heat for 1 hour, heating to 700 ℃ at the heating rate of 5 ℃/min, preserving heat for 2 hours, and naturally cooling to obtain a carbon source coated and bonded graphite/SiO composite material B;
(3) transferring the composite material B into a box furnace, heating to 1000 ℃ at the heating rate of 5 ℃/min, preserving the heat for 2 hours, and then naturally cooling to obtain the SiO/graphite composite negative electrode material.
Example 4
A preparation method of a high-first-efficiency SiO graphite composite negative electrode material comprises the following steps:
(1) taking SiO, artificial graphite, citric acid and LiH according to the mass ratio of 1:1:0.3:0.01, respectively, sucking the materials into a VC mixer through a vacuumizing pipeline, quickly stirring for 30 minutes, and stopping the machine after the four materials are effectively mixed; wherein the grain diameter of SiO is 0.5 μm, and the grain diameter of artificial graphite is 8 μm;
(2) transferring the mixed material to a vertical granulation kettle through vacuum equipment, introducing helium gas, stirring at 100 revolutions per minute, heating to 500 ℃ at the heating rate of 10 ℃/min, preserving heat for 30min, heating to 800 ℃ at the heating rate of 10 ℃/min, preserving heat for 1 hour, and naturally cooling to obtain a carbon source coated and bonded graphite/SiO composite material B;
(3) transferring the composite material B into a box furnace, heating to 1100 ℃ at the heating rate of 10 ℃/min, preserving the heat for 1 hour, and then naturally cooling to obtain the SiO/graphite composite negative electrode material.
Example 5
The preparation method of the high-first-efficiency SiO graphite composite negative electrode material is different from the embodiment 4 in that citric acid is subjected to modification treatment, and the specific operation is as follows:
1) dispersing citric acid in deionized water, adding titanium dioxide under stirring to ensure that the mass concentration of the titanium dioxide in the system is 180g/L and the mass of the citric acid is 0.1 percent of that of the titanium dioxide, performing wet ball milling for 20min, and drying to obtain titanium dioxide grafted citric acid;
2) respectively dissolving titanium dioxide grafted citric acid and polyethylene oxide in dimethyl sulfoxide to prepare solutions, dropwise adding a titanium dioxide grafted citric acid solution into a polyethylene oxide solution according to the molar ratio of 7:10 of the citric acid to the polyethylene oxide solution, heating and stirring at 60 ℃ for reaction for 5 hours, cooling a reaction solution, dropwise adding the cooled reaction solution into an ethanol solution containing 10 wt% of NaOH, precipitating solids, washing the solids, and drying to obtain the modified citric acid.
Example 6
The preparation method of the high-first-efficiency SiO graphite composite negative electrode material is different from the embodiment 4 in that citric acid is subjected to modification treatment, and the specific operation is as follows:
1) dispersing citric acid in deionized water, adding titanium dioxide under stirring to ensure that the mass concentration of the titanium dioxide in the system is 300g/L and the mass of the citric acid is 0.05 percent of that of the titanium dioxide, performing wet ball milling for 30min, and drying to obtain titanium dioxide grafted citric acid;
2) respectively dissolving titanium dioxide grafted citric acid and polyethylene oxide in dimethyl sulfoxide to prepare solutions, dropwise adding a titanium dioxide grafted citric acid solution into a polyethylene oxide solution according to the molar ratio of 3:10 of the citric acid to the polyethylene oxide, heating and stirring at 100 ℃ for reaction for 3 hours, cooling a reaction solution, dropwise adding the cooled reaction solution into an ethanol solution containing 5 wt% of NaOH, precipitating a solid, washing the solid, and drying to obtain the modified citric acid.
Example 7
The preparation method of the high-first-efficiency SiO graphite composite negative electrode material is different from the embodiment 4 in that citric acid is subjected to modification treatment, and the specific operation is as follows:
1) dispersing citric acid in deionized water, adding titanium dioxide under stirring to ensure that the mass concentration of the titanium dioxide in the system is 200g/L and the mass of the citric acid is 0.08 percent of that of the titanium dioxide, performing wet ball milling for 25min, and drying to obtain titanium dioxide grafted citric acid;
2) respectively dissolving titanium dioxide grafted citric acid and polyethylene oxide in dimethyl sulfoxide to prepare solutions, dropwise adding a titanium dioxide grafted citric acid solution into a polyethylene oxide solution according to the molar ratio of the citric acid to the polyethylene oxide of 5:10, heating and stirring at 70 ℃ for reaction for 4 hours, cooling a reaction solution, dropwise adding the cooled reaction solution into an ethanol solution containing 8 wt% of NaOH, precipitating a solid, washing the solid, and drying to obtain the modified citric acid.
Comparative example 1
A preparation method of a high-first-efficiency SiO graphite composite negative electrode material comprises the following steps:
(1) taking SiO and asphalt according to the mass ratio of 1:0.1, respectively, sucking the SiO and the asphalt into a VC mixer through a vacuum-pumping pipeline, quickly stirring for 30 minutes, and stopping the mixer after the two materials are effectively mixed;
(2) transferring the mixed material into a vertical granulating kettle through vacuum equipment, introducing inert atmosphere, stirring at the speed of 100 revolutions per minute, heating to 300 ℃ at the heating rate of 3 ℃/min, preserving heat for 1 hour, heating to 700 ℃ at the heating rate of 5 ℃/min, preserving heat for 2 hours, and naturally cooling to obtain a carbon source coated and bonded SiO material C;
(3) respectively taking graphite and asphalt according to the mass ratio of 1:0.1, sucking the graphite and the asphalt into a VC mixer through a vacuum-pumping pipeline, quickly stirring for 30 minutes, and stopping the machine after the two materials are effectively mixed;
(4) transferring the mixed material into a vertical granulating kettle through vacuum equipment, introducing inert atmosphere, stirring at the speed of 100 revolutions per minute, heating to 300 ℃ at the heating rate of 3 ℃/min, preserving heat for 1 hour, heating to 700 ℃ at the heating rate of 5 ℃/min, preserving heat for 2 hours, and naturally cooling to obtain a carbon source coated and bonded graphite material D;
(5) and mixing the materials C and D, transferring the mixture to a box furnace, heating to 1000 ℃ at the heating rate of 5 ℃/min, preserving the temperature for 2 hours, and then naturally cooling to obtain the SiO/carbon/graphite composite negative electrode material.
Performance testing
The preparation of the pole piece, the assembly of the button cell and the electrochemical performance test were carried out on the SiO/graphite composite negative electrode materials prepared in examples 1 to 5 and comparative example 1. The method comprises the following specific steps: mixing the SiO/graphite composite negative electrode material prepared in the examples 1-5 and the comparative example 1 with conductive carbon black, sodium carboxymethylcellulose (CMC) and Styrene Butadiene Rubber (SBR) according to the mass ratio of 90:5:2:3, adding deionized water as a solvent, and stirring; uniformly stirring, uniformly coating on a copper foil current collector by using coating equipment, baking for 24 hours in a vacuum drying oven at 90 ℃, then uniformly pressing by using a roll machine, and finally preparing a circular pole piece with the diameter of 14mm by using a sheet punching machine; and then, a metal lithium sheet is taken as a counter electrode, a diaphragm is a polypropylene membrane (Celgard 2300), an electrolyte is a mixed solution of 1mol/L lithium hexafluorophosphate and vinyl carbonate and dimethyl carbonate in equal volume ratio, a 2025 button cell is assembled in a vacuum glove box filled with high-purity nitrogen, and electrochemical performance tests are carried out, wherein the test results are shown in the following table. During testing, the charge and discharge cycles are carried out at 0.1C multiplying power (1C is calculated by 500 mAh/g), the voltage range is 0-1.5V, and the cycle times are 100 times. And disassembling the battery after the battery is circulated for 100 weeks to measure the expansion rate of the pole piece.
As can be seen from the data in table 1, the SiO/graphite composite negative electrode materials prepared in examples 1 to 5 all have higher first coulombic efficiency and good cycle stability, while comparative example 1 has severe cycle attenuation, which proves that SiO is uniformly dispersed and sandwiched in the graphite layer, effectively relieves volume expansion, avoids rapid pulverization of SiO, thereby greatly improving cycle stability, and the introduction of Li salt greatly improves first effect. It can also be seen from the expansion rate during the material cycle that the volume expansion is suppressed due to the SiO intercalation in the graphite. The difference between example 5 and example 4 is that citric acid is modified, and the modified citric acid has improved performances from the results, which shows that the modified citric acid has a positive effect on inhibiting the volume expansion and pulverization of SiO.
Although the present invention has been described with reference to a preferred embodiment, it should be understood that various changes, substitutions and alterations can be made herein without departing from the spirit and scope of the invention as defined by the appended claims.
Claims (8)
1. A preparation method of a high-first-efficiency SiO graphite composite negative electrode material is characterized by comprising the following steps:
(1) uniformly mixing SiO, graphite, an organic carbon source and Li salt according to the mass ratio of 1 (1-10) to 0.3-5 to 0.01-1 to obtain a mixture A, wherein the grain diameter of the SiO is smaller than that of the graphite; the organic carbon source is citric acid, and the citric acid is modified by the following specific operations:
1) dispersing citric acid in deionized water, adding titanium dioxide under stirring to ensure that the mass concentration of the titanium dioxide in the system is 180-300g/L and the mass of the citric acid is 0.05-0.1 percent of that of the titanium dioxide, performing wet ball milling for 20-30min, and drying to obtain the titanium dioxide grafted citric acid;
2) respectively dissolving titanium dioxide grafted citric acid and polyoxyethylene in dimethyl sulfoxide to prepare solutions, dropwise adding a titanium dioxide grafted citric acid solution into a polyoxyethylene solution according to the molar ratio (3-7) of the citric acid to the polyoxyethylene, heating and stirring at 60-100 ℃ for reaction for 3-5 hours, cooling the reaction solution, dropwise adding the reaction solution into an ethanol solution of NaOH, separating out a solid, washing the solid, and drying to obtain modified citric acid;
(2) transferring the mixture A to granulation equipment for granulation in an inert gas atmosphere to obtain a SiO/graphite composite material precursor B;
(3) and calcining the composite material precursor B at high temperature in the atmosphere of inert gas, and naturally cooling to room temperature to obtain the carbon-coated SiO/graphite composite negative electrode material.
2. The preparation method of the high-efficiency SiO graphite composite anode material according to claim 1, wherein the particle size of the SiO in the step (1) is 0.5-5 μm.
3. The preparation method of the high-efficiency SiO graphite composite anode material according to claim 1, wherein the Li salt in the step (1) is one or more of LiH, LiOH and n-butyllithium.
4. The preparation method of the high-efficiency SiO graphite composite anode material according to claim 1 or 3, wherein the graphite in the step (1) is one or more of artificial graphite, natural graphite and expanded graphite.
5. The preparation method of the high-efficiency SiO graphite composite anode material according to claim 1, wherein the granulation equipment in the step (2) is one of a spray granulator, a VC coater, a vertical granulation kettle and a horizontal granulation kettle.
6. The preparation method of the high-efficiency SiO graphite composite anode material as claimed in claim 1 or 5, wherein the granulation process in the step (2) is as follows: heating to 200-500 ℃ at the rate of 3-10 ℃/min, and preserving the heat for 30-60min, and then heating to 600-800 ℃ at the rate of 3-10 ℃/min, and preserving the heat for 1-3 h.
7. The preparation method of the high-efficiency SiO graphite composite anode material according to claim 1, wherein the high-temperature calcination process in the step (3) comprises the following steps: heating to 800-.
8. The preparation method of the high-efficiency SiO graphite composite anode material according to claim 1, wherein the inert gas comprises one or more of helium, argon and nitrogen.
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| CN202110295376.XA CN113363473B (en) | 2021-03-19 | 2021-03-19 | Preparation method of high-first-efficiency SiO graphite composite negative electrode material |
| PCT/CN2021/105896 WO2022193498A1 (en) | 2021-03-19 | 2021-07-13 | Method for preparing high-initial-coulombic-efficiency sio/graphite composite negative electrode material |
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| CN114975950A (en) * | 2022-06-14 | 2022-08-30 | 雅安天蓝新材料科技有限公司 | Carbon-silicon composite material and preparation method thereof |
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| CN110600662A (en) * | 2019-09-19 | 2019-12-20 | 湘潭大学 | Polyvinylidene fluoride-hexafluoropropylene/titanium dioxide composite membrane and preparation method and application thereof |
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