Enhancing high volumetric energy density of supercapacitors through diatomic reconstruction of layered double hydroxides

Double atom regulation and synergistic phosphorus doping and oxygen vacancy (O V ) engineering are effective strategies for optimizing the electronic structure of layered double hydroxides (LDHs). In this study, a self-supporting P-doped O V -(Co 0.5 Ni 0.5 ) 3 V 2 O 8 electrode with interpenetrating carbon nanotube networks was synthesized via cation/anion co-reconstruction. Leveraging vanadium's high valence states, the dual-atom system creates a microporous architecture that enables precise charge redistribution, enhancing both electrical conductivity and OH - adsorption capacity. Density functional theory confirms that P-O V synergy reduces charge transfer resistance while optimizing ion diffusion pathways and charge storage kinetics. The optimized electrode achieves outstanding performance: 3807.9 F cm -3 volumetric capacitance at 1 A g -1 and exceptional cycling stability (100% capacity retention over 10000 cycles). Assembled asymmetric supercapacitors deliver 158.1 Wh L -1 energy density at 992 W L -1 power density, surpassing most reported LDH-based devices. This dual-atom charge redistribution mechanism establishes a universal paradigm for designing high-capacity electrodes, addressing critical challenges in energy storage materials through simultaneous electronic structure modulation and microstructural stabilization. A high-performance hybrid supercapacitor cathode material was developed through dual-atom regulation and synergistic optimization of P-doping and oxygen vacancies. • The performance of O V -CNVP@CNT is synergistically improved by phosphorus doping and oxygen vacancies through the dual atom control strategy. • The O V -CNVP@CNT electrode shows the specific capacity of 3807.9 F cm -3 at 1 A g -1 . • DFT analysis demonstrates significant enhancement of material OH - adsorption energy by the synergistic effect of P doping and oxygen vacancies. • The supercapacitor delivers a high energy density of 158.1 Wh L -1 at power density of 992 W L -1 .