Bismuth Oxychloride/MXene symmetric supercapacitor with high volumetric energy density

Since the discovery of two-dimensional (2D) graphene, a new class of 2D materials with excellent electrical conductivity has recently been attracting attention in studying promising electrode materials in energy storage applications. Herein, bismuth oxychloride nanosheets-immobilised Ti3C2Tx MXene material (TCBOC) is synthesised by a facile and cost-effective chemical bath deposition (CBD) route. The bismuth oxychloride (BiOCl) nanosheets are grown and immobilised on surfaces of Ti3C2Tx-MXene flakes. An electrode based on the TCBOC nanocomposite exhibited a remarkably volumetric specific capacitance of 396.5 F cm-3 at 1 A g−1 and 228.0 F cm-3 at 15 A g−1. Furthermore, a symmetric supercapacitor (SSC) assembled using TCBOC material proves to have a high energy density of 15.2 Wh kg−1 at a power density of 567.4 W kg−1 compared to SSCs using previously reported Ti3C2Tx MXene materials. The SSC shows cycle life retention of 85.0% after 5000 cycles (at 5 A g−1). The enhanced capacitive performance is attributed to the increased surface area due to BiOCl nanosheets anchored on a 2D MXene surface, the activities of BiOCl sheets, and the excellent conductivity of a Ti3C2Tx MXene material.