Preparation method of tin carbon composite material for negative electrode of lithium ion batteries

Abstract

The invention discloses a preparation method of a tin carbon composite material for negative electrode of lithium ion batteries. The preparation method comprises the following steps: the method that a medium is adopted to block discharge plasma for assisting high-energy ball milling is adopted to ball mill the mixed powder of tin and graphite for 2.5h to 20h, thus obtaining the tin carbon composite powder; and then the tin carbon composite powder is made into an lithium ion electrode plate which is then assembled into batteries, wherein the mass of a graphite raw material accounts 30 to 70 percent of the total mass of the mixed powder; during the ball milling process, the mass ratio of the grinding balls to the ball powder of the tin and graphite mixed powder is 30:1 to 70:1; and the medium adopts an inert gas which is not reacted with Sn, such as helium, neon, argon, krypton, xenon or nitrogen. The preparation method can effectively improve ball-milling efficiency, keep lamellar integrity of graphite, improve first reversible capacity and cycle life, and refine Sn particles to enable the relative volume change of a working electrode in the charging and discharging process to be reduced and improve the cycle performance of the lithium batteries.

Description

technical field [0001] The invention relates to the field of lithium ion batteries, in particular to a preparation method of a tin-carbon composite material for lithium ion battery negative electrodes. Background technique [0002] At present, most commercially used lithium-ion batteries use carbon materials as negative electrodes, but the energy density and specific energy density of carbon materials are low (the theoretical specific capacity of carbon materials is only 372mA hg -1 . With the rapid development of the electronics industry, the capacity of existing lithium batteries has been difficult to meet the needs of various fields. Many metal materials (such as Sn, Si, Al) can react with lithium to form alloys, thus having a high theoretical capacity. Sn can form Li with Li 4.4 Sn, the theoretical capacity is 990mA·hg -1 , is expected to replace carbon materials and become a commercial anode material for lithium-ion batteries. However, during the charging and disch...

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Problems solved by technology

For the former, the ball milling time is as long as 150h in order to refine the powder, and the long-time ball milling makes C amorphous, introduces a large number of defects, and greatly increases the first irreversible capacity; although the latter ball milling time is shortened to 25h, it adds a large amount of Inactive material, sacrificing its overall specific capacity

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