一种通用的一步原位合成策略制备金属硫化物/还原氧化石墨烯纳米片用于高性能超级电容器

A generalized one-step in situ formation of metal sulfide/reduced graphene oxide nanosheets toward high-performance supercapacitors

金属硫化物在超级电容器领域具有良好的应用前景,但缓慢的反应动力学抑制了其电化学性能.增加电化学表面积并与碳材料结合可以改善其电化学性能.然而,寻求一种简单通用的方法制备金属硫化物和导电碳的复合材料仍具有挑战性.本文设计了一种简单的一步热解法,在温和的条件下将硫化钴镍(CoNi2S4)原位生长在还原氧化石墨烯(rGO)纳米片上.制备的硫化镍钴/还原氧化石墨烯(CoNi2S4/rGO)材料具备纳米片结构,可以提供大量的活性位点,有效地缩短电子/离子的扩散路径.得益于这些优点,所制备的CoNi2S4/rGO电极材料在电流密度分别为2和20 A g^−1时具有1526和988 F g^−1的高比电容.基于CoNi2S4/rGO的非对称超级电容器工作电压窗口为1.6 V,在功率密度为798 W kg^−1时能量密度高达54.8 W h kg^−1.在3 A g^−1下循环8000次后,其容量保持率为93.7%.利用该方法可获得一系列金属硫化物/rGO复合材料,此通用策略可推广应用于各种能源器件电极材料的制备.

Metal sulfides are promising candidates for supercapacitors,but their slow reaction kinetics hinders their electrochemical performance.Large electrochemical surface area and combination with conductive carbon are potential methods to improve their capacitive performance.However,seeking for a generalized and simple approach to prepare two-dimensional composites of metal sulfide and conductive carbon for supercapacitors is challengeable.Herein,a generalized and facile one-step pyrolysis method was designed for in situ growth of cobalt nickel sulfides(CoNi2S4)on reduced graphene oxide(rGO)nanosheets(CoNi2S4/rGO)under mild conditions.The as-prepared CoNi2S4/rGO materials possess the nanoparticles-on-nanosheets structure,which is effective to provide a myriad of active sites and optimized electron/ion diffusion pathway.Benefiting from those advantages,the resultant CoNi2S4/rGO electrodes exhibit impressed specific capacitances of 1526 and 988 F g^−1 at 2 and 20 A g^−1,respectively.The supercapacitors based on CoNi2S4/rGO showcase an operation potential window of 1.6 V,and energy density of 54.8 W h kg^−1 at the power density of 798 W kg^−1.The capacitance retention of the supercapacitor is about 93.7%after 8000 cycles at 3 A g^−1.Moreover,a series of metal sulfide/rGO hybrids are obtained by this generalized strategy,which could be extended to construct electrode materials for various energy devices.