The toughening design of pseudocapacitive materials via graphene quantum dots: Towards enhanced cycling stability for supercapacitors

Poor cycling stability of various pseudocapacitive electrode materials has been a major obstacle facing in front of the development of supercapacitors. Herein, we for the first time bring the toughening mechanism into the design of pseudocapacitive electrode materials to enhance the cycling stability. A hybrid of two-dimensional (2D) NiCo-layered double hydroxides (LDHs) and zero-dimensional (0D) graphene quantum dots (GQDs), in which NiCo-LDHs provide high specific capacitance and GQDs serve as the toughening materials, is designed here. As a result, the GQDs/NiCo-LDH shows high specific capacitance of 2220 F g⁻¹ under a current density of 1 A g⁻¹, and the cycling stability is also significantly enhanced. The flexible all-solid-state GQDs/NiCo-LDH//AC supercapacitor delivers a high energy density of 50.84 W h kg⁻¹, power density of 8 kW kg⁻¹, and superior flexibility. This work proves that GQDs are promising materials to enhance the performance of pseudocapacitive materials, and provides some new insights for the designing of pseudocapacitive electrode materials.