Incorporating Interstitial Carbon Atoms and Graphene Quantum Dots in Crystalline Ni(OH)Cl for Ultrastable and Superior Rate Supercapacitors

Despite their high theoretical capacity, Ni-based materials are hindered by significant issues such as structural degradation, low intrinsic conductivity, and sluggish kinetics, resulting in poor stability and rate performance. Herein, the Ni(OH)Cl-ICA-GQDs incorporated with interstitial carbon atoms (ICAs) and graphene quantum dots (GQDs) are proposed to radically reverse its structural stability and electronic transport capability. ICAs can induce lattice micro-strain that adjusts bond lengths and angles, leading to intrinsically ameliorated structural stability under alkaline and even acidic conditions. GQDs promote the formation of micro-conductive circuits, optimizing the electronic configuration and redox kinetics. As a result, the Ni(OH)Cl-ICA-GQDs electrode achieves exceptional cyclic stability (91.5% retention after 20 000 cycles versus 70.3% retention after 2000 cycles for Ni(OH)Cl) and remarkable rate capability (312C g⁻¹ at 100 A g⁻¹ vs 109C g⁻¹ at 50 A g⁻¹ for Ni(OH)Cl). Furthermore, the Ni(OH)Cl-ICA-GQDs//AC hybrid supercapacitor achieves an ultrahigh power density of 41.5 kW kg⁻¹ with an energy density of 28.8 Wh kg⁻¹, surpassing most Ni-based supercapacitors. This approach offers a promising strategy for the precise modification of high-performance electrodes for energy storage applications.