静电纺氧化锰复合碳纳米纤维柔性膜的电化学性能

Electrochemical Performance of Flexible Electrospun Carbon-MnO_x Hybrid Nanofibrous Membranes for Supercapacitors

采用一步法静电纺丝技术制备了具有超亲水特性的氧化锰/碳纳米纤维(MnO_x/CNFs)复合柔性膜电极材料,并通过X射线衍射、扫描电子显微镜和透射电子显微镜等对复合材料进行了表征.电化学性能测试结果表明,复合材料的电容性能优于单一材料,醋酸锰质量分数为40%时制得的复合纳米纤维电极(MC-4)在1 A/g电流密度下,于2 mol/L KOH电解液中的比电容高达1112.5 F/g,10 A/g电流密度下循环3000次比容量保持在93.4%,具有很好的稳定性.MnO_x/CNFs复合材料电化学性能增强一方面是由于三维超亲水纤维膜结构有利于电解液的快速浸润渗透,从而极大缩短了传输到材料基质的有效路径;另一方面是由于碳和MnO_x的协同效应,包裹在MnO_x粒子周围的碳层避免了MnO_x在充放电过程中的体积膨胀效应,这2种叠加机制促进了电化学性能的提升.

Super-hydrophilic flexible MnOx/carbon nanofibers（MnOx/CNFs） composites were fabricated by electrospinning technique. The nanostructures of MnOJCNFs were proved by XRD, SEM and TEM measurements. The results confirmed that the composites possessed higher electrochemical capacitance than each individual component as supercapacitor electrode materials. The hybrid nanofibrous electrodes with 40% （mass fraction） manganese acetate（MC-4） exhibits extremely high specific capacitance of 1112. 5 F/g at a current density of 1 A/g and superior cycling stability such as high capacitance retention of 93.4% at a current density of 10 A/g over 3000 charge-discharge cycles in a 2 mol/L KOH electrolyte. The enhanced electrochemical performance of the composite electrode originates from the combined effects of the two components as follows： （1） 3D superhydrophilic MnOx/CNFs network over a relatively larger surface area reduces the difusion resistance of the electrolyte into the electrode matrix; （2） the synergistic effect between carbon and MnOx. Carbon layer wrapped around MnOx particles can prevent structural damage to the MnOx during charge/discharge processes and contribute to an increased capacitance of the composite,