基于天然纤维素物质的C/TiO_(2)/CuMoO_(4)微-纳结构复合纤维材料构筑及其电化学性能

Fabrication and electrochemical performance of micronanostructured C/TiO_(2)/CuMoO_(4) fibrous composite based on natural cellulose

锂离子电池作为目前常见的储能器件,具有能量密度高、功率密度大、价格低廉、绿色环保等特点,已经得到广泛应用。目前发展非石墨基负极材料以提升电池性能的需求日益迫切,钼酸铜由于理论比容量高、还原电位低,是一种极具潜力的负极材料。本研究工作以天然棉花纤维为结构支架和碳源构建了一种具有微-纳结构的C/TiO_(2)/CuMoO_(4)复合纤维材料,解决了钼酸铜作为电极材料时导电性差和易粉碎的问题,表现出优异的电化学性能。首先对棉花纤维进行酸碱预处理提高其比表面积;然后通过溶胶-凝胶法在纤维表面沉积超薄二氧化钛层;再利用层层自组装(LbL)技术沉积钼酸铜层;最后在氩气氛围中于500℃煅烧6h得到微-纳结构的C/TiO_(2)/CuMoO_(4)复合纤维材料。当用作电极材料时,在100mA/g的电流密度下,钼酸铜质量分数为22.8%的复合材料首圈放/充电比容量分别为1212mAh/g和675mAh/g,库仑效率为55.7%,经过200圈循环后,其比容量为403mAh/g,保持率为59.7%,具有良好的循环性能和倍率性能。这种微-纳结构提高了复合材料的导电性和稳定性,从而增强了其电化学性能。

Lithium-ion batteries(LIBs)have been widely applied as common energy storage devices owing to their high energy and power densities,low cost,environmental friendliness,etc.The demand for developing nongraphite-based anode materials to improve battery performance is increasingly urgent.CuMoO_(4) is a potential anodic material owing to its high theoretical specific capacity and low reduction potential.To address the problems of poor electrical conductivity and irreversible structural pulverization when CuMoO_(4) is used as an anodic material,micro-nanostructured C/TiO_(2)/CuMoO_(4) fibrous composite was fabricated using natural cotton fibers as the structural scaffold and C source,showing excellent electrochemical performance.The cotton fibers were first pretreated with H_(2)SO_(4) and NaOH to increase the specific surface area,and thereafter,ultrathin TiO_(2) layers were deposited on the fiber surfaces using a sol-gel method.The CuMoO_(4) layers were further deposited via the layer-by-layer(LbL)self-assembly technique.The micro-nanostructure C/TiO_(2)/CuMoO_(4) fibrous composite was obtained via calcination at 500℃in an Ar atmosphere for 6 h.When applied as an anodic material for LIBs,the composite with 22.8%CuMoO_(4) delivered initial discharge and charge capacities of 1212 mAh/g and 675 mAh/g,respectively,with a coulomb efficiency of 55.7%;after 200 charge-discharge cycles at 100 mA/g,the specific capacity was 403 mAh/g with a capacity retention of 59.7%,showing good cycle and rate performances.The conductivity and structural stability of the composite are improved owing to its micro-nanostructure,enhancing electrochemical performances.