锂离子电池负极材料的制备 ——用气相氧化法改性天然石墨

Preparation of Anode Material for Lithium Ion Secondary Battery ——The Modification of Natural Graphite by Gas-Phase Oxidation Method

在 50 0℃、550℃和 60 0℃下用空气作氧化剂 ,将普通的天然石墨进行氧化改性。改性后 ,除去了一些活性高的缺陷结构 ,提高了石墨结构的稳定性及电子自旋共振信号的相对强度 ;在除去缺陷结构的同时 ,增加了纳米级微孔及通道的数目。另外 ,氧化时形成的氧化物层与石墨结合得比较紧 ,可作为致密的钝化膜 ,并防止石墨结构的破坏。这些因素的变化有利于锂的嵌入和脱出 ,抑制电解质的分解 ,导致可逆容量从 2 51mAh/g增加到 350mAh/g ,第 1次循环的充放电效率达 80 %以上 ,前 10次循环的可逆容量没有衰减。

The physicochemical properties of general natural graphite were modified by gas-phase oxidation using air as oxidant at temperatures of 500℃,550℃ and 600℃.This gas-phase oxidation eliminated some imperfect structures with high activity,stabilized the graphite structure and increased the relative intensity of electron spinning resonance.When the imperfect structures were eliminated,the number of nano-meter micropores and channels were increased and an oxide layer that bonded strongly with graphite structure was formed.This oxide layer could act as a dense passivating film and prevent destroying of graphite structure.Changes of these factors favored intercalation and deintercalation of lithium,inhibited decomposition of electrolytes and resulted in enhancement of reversible lithium capacity from 251mAh/g to 350mAh/g.In addition,coulombic efficiency in the first cycle could be above 80% and reversible capacity did not fade in the first 10 cycles.