Interlayer ionic diffusion driven in situ QD-deposition in the Co9S8–LDH hybrid supercapacitor electrode†

The micro/nano-structural design of 2D interlayers greatly enhances the electrochemical energy and kinetics of the supercapacitor electrode. Herein, a hetero-Co₉S₈ QD-doped 2D CoNi-LDH with the proper content was constructed through diverse sulfurization time, showing a 3D flower-like microsphere. The highly dispersed active QDs on 2D layers promoted both rapid ion/electron transfer kinetics and electrochemical storage capacity, which were evidenced by experiments and density functional theory calculations. As a result, the assembled hybrid supercapacitor QDs-Co₉S₈/CoNi-LDH//activated carbon displays a maximum energy density of 33.3 Wh kg⁻¹ at a power density of 820.0 W kg⁻¹. Furthermore, the in-depth analysis of interlayer ion diffusion and formation of quantum dots in heterostructure provides a good way for synthesizing high-performance electrode materials with adjustable size and composition.