Takovite-derived 2-D Ni/Al double hydroxide monolayer and graphene hybrid electrodes for electrochemical energy storage applications with high volumetric capacitance

Exfoliated Ni/Al layered double hydroxide (LDH) is a high-aspect-ratio material possessing enhanced electrical conductivity and exposure of electrochemically active sites compared with its bulk counterpart. However, its application in electrochemical energy storage is rarely explored. In this work, 2D Ni/Al LDH with a single layer thickness was achieved by exfoliation of takovite crystals. A novel electrode consisting of self-assembled layered Ni/Al LDH and graphene was fabricated for electrochemical energy storage device. Attributed to the ideal structure of this hybrid electrode combining improved conductivity and site exposure of exfoliated Ni/Al LDH and highly conductive graphene interlayers, the electrode has a high volumetric capacitance of 818.9 F/cm3, an outstanding rate capability of 81.1% retention after a 10 fold increase in current, and a good cycling stability, which demonstrates its great potential for supercapacitor applications.