Nitrogen-doped carbon-coated graphite negative electrode material and preparation method thereof

Abstract

The invention discloses a nitrogen-doped carbon-coated graphite negative electrode material and a preparation method thereof. The nitrogen-doped carbon-coated graphite negative electrode material is composed of the following raw materials in weight ratio: 80%-95% of graphite and 5%-20% of ionic liquid, wherein the outer surface of graphite is uniformly coated with the ionic liquid to form a core-shell type structure; the preparation method comprises the following steps: firstly coating, and then carbonizing. The graphite negative electrode material has relatively high compaction density, specific capacity and initial efficiency; the problem that an artificial graphite material is large in irreversible capacity loss and low in specific capacity when applied to real preparation of a lithium battery negative electrode is solved, and the rate capability and the circulating performance of a lithium ionic battery are greatly improved by doping with nitrogen; therefore, the material can be well applied to a power battery with high performance requirement. The preparation method disclosed by the invention is simple in process, convenient to operate and less in production equipment, thereby further reducing the cost; the method is convenient for popularization and application and suitable for large-scale production.

Description

technical field [0001] The invention relates to the technology in the field of battery electrode material preparation, in particular to a nitrogen-doped carbon-coated graphite negative electrode material and a preparation method thereof. Background technique [0002] With the deepening of the global energy crisis, the depletion of oil resources and the increasing harm of air pollution and global temperature rise, it is imperative to develop clean energy. In the development of new energy, lithium-ion batteries, which have the advantages of high working voltage, high energy density, stable discharge voltage, long cycle life and environmental friendliness, are widely used. Anode materials are one of the key factors to evaluate the overall performance of lithium-ion batteries. At present, the anode material of commercially used lithium batteries is mainly graphite, which has the characteristics of low lithium extraction / intercalation potential (0-0.25V vs Li / Li+), high capacity...

AI Technical Summary

Problems solved by technology

However, graphite-based materials still have some shortcomings as lithium-ion negative electrode materials, mainly in: weak interlayer interaction between graphite layers, poor compatibility with electrolyte, solvent molecules will be inserted into graphite layers during charging and discharging, resulting in graphite flakes Peeling of layers resulting in poor cycle performance

[0003] Chinese patent CN 103682350 B discloses a lithium battery negative electrode material coated with modified artificial graphite in pitch liquid phase. The modified artificial graphite negative electrode material has improved initial efficiency and specific capacity, but still only has an initial efficiency of less than 94%. The specific capacity is less than 360, and there is still room for improvement

[0004] Chinese patent CN101604743A uses heteroatom-doped resin polymer pyrolytic carbon to coat graphite material, which significantly improves the electrical properties of graphite, but there are also some problems, such as poor affinity between resin materials and graphite, resin heat During the solution process, there are many volatiles, and the specific surface area is higher, which will affect the tap density, compaction density, etc.

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