碳改性二硫化钼纳米片的制备及其储钠性能

Preparation and sodium storage performance of carbon modified molybdenum disulfide nanosheets

二硫化钼(MoS2)作为过渡金属硫化物的典型代表之一,具有二维层状结构(层间距为0.62 nm)和较高的理论比容量(670 mAh·g^(-1)),是一种很有前途的储钠材料。但因其较差的电子电导率和较弱的层间引力,极大地限制了钠离子电池(SIBs)的储钠性能。通过溶剂热法成功制备碳改性二硫化钼纳米片(MoS2/C-H)。碳材料和MoS2的成功复合一方面有效提高材料表面和内部的电子电导率;另一方面,使得MoS2的层间距从初始的0.62 nm宽化到1.00 nm,不仅有利于钠离子的快速脱嵌,还能有效缓解充放电过程中的体积膨胀问题,从而显著提高MoS2作为SIBs负极材料的循环稳定性和倍率性能。电化学性能测试结果显示在0.5 A·g^(-1)电流密度下,MoS2/C-H电极循环200圈后仍可维持320 mAh·g^(-1)的可逆比容量。此外,MoS2/C-H电极还具有良好的倍率性能,在0.5,1,2,5和10 A·g^(-1)电流密度下,比容量分别为437,409,379,337和299 mAh·g^(-1)。这项工作为其他过渡金属硫化物的结构设计提供了新的思路。

Molybdenum disulfide(MoS2),as one of the typical representatives of the transition metal sulfides,is a promising material for sodium storage with a two-dimensional layered structure(layer spacing of 0.62 nm)and a high theoretical specific capacity(670 mAh·g^(-1)).However,as an anode material for sodium ion batteries(SIBs),due to the poor electronic conductivity and weak interlayer attraction,the sodium storage performance of MoS2 was limitd.In this paper,MoS2/C-H nanosheets were successfully prepared by a solvothermal method.On the one hand,the electronic conductivity on the surface and inside of the material was effectively improved;On the other hand,the layer spacing of MoS2 was broadened from the initial 0.62 nm to 1.00 nm,which not only facilitates the rapid de-embedding of the sodium ions,but also effectively alleviates the volume expansion problem during the charging and discharging process.Thus,the cycle stability and rate performance of MoS2 as an anode material of SIB were significantly improved.The electrochemical performance test results show that the MoS2/C-H electrode can maintain a reversible specific capacity of 320 mAh·g^(-1)after 200 cycles at a current density of 0.5 A·g^(-1).In addition,the MoS2/C-H electrode has good rate performance with capacities of 437,409,379,337,and 299 mAh·g^(-1)at the current densities of 0.5,1,2,5,and 10 A·g^(-1),respectively.This work provides new ideas for the structural design of other transition metal sulfides.