Carbon-coated silicon negative electrode material with hollow structure and preparation method thereof

A negative electrode material, carbon coating technology, applied in the field of electrochemical energy storage, can solve problems such as silicon powder pulverization, and achieve the effect of solving silicon powder pulverization and inhibiting excessive volume expansion of silicon

CN112678799AInactive Publication Date: 2021-04-20SICHUAN UNIV
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Patent Information

Authority / Receiving Office
CN · China
Patent Type
Applications(China)
Current Assignee / Owner
Publication Date
2021-04-20
Estimated Expiration
Not applicable · inactive patent

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Abstract

The invention discloses a carbon-coated silicon negative electrode material with a hollow structure prepared by taking ZIF-67 as a template and a preparation method of the carbon-coated silicon negative electrode material, and the preparation method comprises the following steps: ultrasonically dispersing silicon powder into methanol, and respectively adding 2-methylimidazole and cobalt salt under a stirring condition; standing, carrying out centrifugal separation, and drying to obtain a precursor Si@ ZIF-67; ultrasonically dispersing the obtained Si @ ZIF-67 in ethanol, and adding the obtained Si @ ZIF67 into a tannic acid solution under a stirring condition; standing, centrifugally separating, washing with ethanol, drying and carbonizing to obtain a product, namely the carbon-coated silicon negative electrode material with the hollow structure. The silicon-carbon negative electrode material prepared by the method can inhibit overlarge volume expansion of silicon in the charging and discharging process to a certain extent, provides a proper space for volume expansion of silicon powder, and can solve the problem of silicon powder pulverization caused by internal stress.
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Description

technical field

[0001] The invention belongs to the field of electrochemical energy storage, and in particular relates to a carbon-coated silicon negative electrode material with a hollow structure and a preparation method thereof. Background technique

[0002] Currently, energy crisis and environmental pollution have posed potential threats to social development and human health. Therefore, it is crucial to design and construct a green and efficient energy conversion and storage device. Lithium-ion batteries have become one of the most promising energy storage devices due to their high energy density, good rate capability, and long cycle life. Graphite is well known as an anode material for commercial lithium-ion batteries, but its low theoretical capacity (372 mAh / g) hinders its application in high-energy-density energy storage. Therefore, various electrode materials have been studied and reported to replace graphite, such as silicon, transition metal oxides, and sulfide...

Examples

Embodiment 1

[0026] (1) Ultrasonically disperse 0.06g of silicon powder in 50mL of methanol, under stirring conditions, add 1.72g of 2-methylimidazole respectively according to the molar ratio of silicon powder, 2-methylimidazole and cobalt nitrate as 1:6:2 and 1.28 g of cobalt nitrate.

[0027] (2) After standing for 2 hours, centrifuge and freeze-dry for 12 hours to obtain the precursor Si@ZIF-67.

[0028] (3) According to the mass ratio of tannic acid to Si@ZIF-67 of 2:5, 0.62 g of tannic acid was added to a 300 mL solution with a volume ratio of ethanol and water of 1:1 and stirred for 10 minutes to obtain a tannic acid solution.

[0029] (4) Ultrasonic disperse the Si@ZIF-67 in step (2) in 30mL ethanol, add the tannic acid solution in step (3) under stirring condition, let stand for 2 hours, centrifuge and wash with ethanol 3 times , freeze-dried for 2 hours.

[0030] (5) The dried product obtained in step (4) was heated up to 800°C for carbonization at a rate of 5°C / min and held fo...

Embodiment 2

[0032] A method for preparing a carbon-coated silicon negative electrode material with a hollow structure is basically the same as that of Example 1, the difference being:

[0033] In step (1), cobalt chloride is used to replace cobalt nitrate, and the dosage is 0.90 g.

Embodiment 3

[0035] A method for preparing a carbon-coated silicon negative electrode material with a hollow structure is basically the same as that of Example 1, the difference being:

[0036] The drying method adopted is ordinary drying at 80° C. for 6 hours.