壳聚糖衍生碳包覆纳米硅复合材料锂离子电池性能研究

Performance of Chitosan-Derived Carbon-coated Nanosilicon Anode Materials for Lithium-ion Batteries

硅负极材料因具有较高的理论容量(Li22Si5合金相对应4200 mAh/g)、较低的工作电压(0.2~0.3 V vs Li/Li+)和地球上丰富的原材料储备,成为代替石墨负极的理想材料之一。但是,低电导率及在循环过程中发生剧烈体积膨胀导致电极失效问题限制了硅负极材料的进一步发展。因此,本工作通过物理法利用壳聚糖和石墨对纳米硅实现碳包覆和复合,制备壳聚糖/石墨@纳米硅复合材料(C/G@Si复合材料),对C/G@Si复合材料的结构、形貌和电化学性能进行研究。结果表明:随着石墨添加量的提高,C/G@Si复合材料的可逆比容量略微下降,循环性能和导电性能显著提高。当添加50%(质量分数)石墨时,在100 mA/g的电流密度下,C/G@Si复合材料的首次放电比容量为1136.1 mAh/g,循环充放电100次后剩余容量保持在658.5 mAh/g,展示出优异的电化学性能,对进一步推广硅碳负极材料具有一定的参考价值。

Silicon anode material has become an ideal material to replace graphite anode due to its high theoretical capacity(4200 mAh/g),low opera-ting voltage(0.2—0.3 V vs Li/Li+)and abundant raw materials on the earth for energy storage.However,the volume expansion of silicon anode materials would lead to electrode degradation during the cycle.Therefore,in this paper,chitosan/graphite@silicon(C/G@Si)composite was prepared by using chitosan and graphite to achieve carbon coating and compositing on nano silicon through physical methods.For C/G@Si,the structure,morphology and electrochemical properties of the composites were studied.The results showed that with the increase of graphite addition,the reversible specific capacity decreased slightly,while the cycle performance and conductivity improved significantly.When 50wt%graphite was added,the specific capacity of the first discharge was 1136.1 mAh/g under the current density of 100 mA/g,and the residual capacity remained at 658.5 mAh/g after 100 cycles of charging/discharging,which exhibits excellent electrochemical performance and has certain reference value for further promotion of silicon-carbon anode materials.