Engineering multiple defects for active sites exposure towards enhancement of Ni3S2 charge storage characteristics

A promising strategy of multiple defects by engineering edges and vacancies simultaneously into the Ni3S2 structure significantly enhances the charge storage. In this work, vacancy scheming not only increases the interplanar spacing for greater availability of active sites but also improves the rate capability from 47% to 60%. Owing to enhance free electrons after vacancies, the resulting Ni3S2 (SNS) shows less band gap which in turn escalates the kinetics of charge storage. Furthermore, edges (thickness similar to 20-30 nm) of hexagonal nanoplatelet form during reduction treatment also contributes towards the additional exposure of active sites to the ions. This synergism imparts Ni3S2 with improved conductivity (one order) and large carrier concentration further augments energy density and cyclic stability. Charge storage in S vacancy induced Ni3S2 (SNS similar to 2994.46 F g(-1)) outperform the Ni3S2 (NS similar to 840.34 F g(-1)) by a factor 3. Whereas, the energy density obtained for SNS electrode is 4 times higher than NS. In addition, disorder structure in SNS lowers the surface energy and thus results in better stability with 88.72% retention. Moreover, asymmetric device SNS//LRGONR shows outstanding electrochemical performance of 53.38 Wh kg(-1)@997.45 W kg(-1). This simplistic approach might shed new light on designing active site rich charge storage materials.