Method for preparing hard carbon material and lithium ion battery

Abstract

The invention discloses a method for preparing a hard carbon material and a lithium ion battery and aims to solve the technical problems of low lithium intercalation capacity and reversible capacity of the lithium ion battery and low high-power charging and discharging performance. The method for preparing the hard carbon material comprises the following steps of: adding an asphalt material into an organic polymer solution which contains an epoxy group to form a cracking precursor; carbonizing to form carbide; crushing to form a hard carbon matrix; adding a coating precursor for coating; and pyrolyzing. The hard carbon material is coated on a cathode of the lithium ion battery and prepared by using the preparation method which comprises the steps of formation of the cracking precursor, carbonization, crushing, coating and pyrolysis. Compared with the prior art, the invention has the advantages that by co-pyrolysis of high-molecular weight organic molecules and asphalt, the hard carbon material which is high in porosity and highly-ordered is synthesized; and the hard carbon material is high in cycle stability, simple in preparation method, low in cost and applicable to the occasions of high capacity, low temperature and high-power discharge.

Description

technical field [0001] The present invention relates to a preparation method of a negative electrode material and a lithium ion battery of a negative electrode material prepared by the method, in particular to a preparation method of a hard carbon negative electrode material and a lithium ion battery of a hard carbon negative electrode material prepared by the method . Background technique [0002] Lithium-ion battery anode materials mainly include carbon materials, alloy materials and composite materials, among which, due to factors such as wide distribution and low price of carbon materials, carbon materials have been widely used in the field of lithium-ion batteries; Materials usually include graphite-like carbon materials and non-graphite-like carbon materials; and graphite-like carbon materials, although they have good electrical conductivity and high crystallinity, have a good charge-discharge platform, but due to the layered structure of graphite, it is different from...

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Problems solved by technology

[0002] Lithium-ion battery anode materials mainly include carbon materials, alloy materials and composite materials, among which, due to factors such as wide distribution and low price of carbon materials, carbon materials have been widely used in the field of lithium-ion batteries; Materials usually include graphite-like carbon materials and non-graphite-like carbon materials; and graphite-like carbon materials, although they have good electrical conductivity and high crystallinity, have a good charge-discharge platform, but due to the layered structure of graphite, it is different from organic The compatibility of solvents is poor. During the charging process of lithium-ion batteries, the solvent molecules are easily embedded in the graphite sheet with lithium ions and destroy the graphite layered structure, resulting in the peeling of the graphite layered structure and the cracking or pulverization of graphite particles. , which in turn leads to the degradation of lithium-ion battery cycles and the reduction of capacity; and due to the particularity of graphite's own structure, its high-power charge and discharge performance is relatively poor, so to a certain extent, it limits the use of graphite-based carbon materials in high-power lithium-ion batteries. The application on the battery also leaves a broader development space for non-graphite carbon materials

[0003] Non-graphite carbon materials include soft carbon and hard carbon, and soft carbon usually needs to be modified before it can be used as a negative electrode material for lithium-ion batteries due to its low output voltage and no obvious charge-discharge platform; hard carbon materials are generally polymers The polymer is formed by pyrolysis at high temperature. Compared with graphite carbon materials, it has many advantages such as low cost, long cycle life, and good power performance, and it has good compatibility with propylene carbonate PC electrolyte. However, due to the existing hard carbon The material preparation method is limited, its porosity is generally low, and the layer structure is not very regular, resulting in relatively small lithium intercalation capacity and reversible capacity of existing hard carbon materials, and poor low temperature performance, which affects the use of hard carbon materials in lithium-ion batteries. Therefore, it is necessary to improve the existing hard carbon material preparation methods

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