Stacking fault disorder induced by Mn doping in Ni(OH)2 for supercapacitor electrodes

Mn-doping engineering route has been demonstrated an effective way to enhance the electronic conductivity of alpha-Ni(OH)(2) as a hybrid supercapacitor electrode material. However, the problem of limited cycling lifetime remains unsolved and the structural evolution of Mn-doping at the atomic level is still under debate. Herein, a novel life span improving strategy is proposed to modulate the electronic configuration and the layer stacking mode of Mn doped Ni(OH)(2) (NiMn-LDH) in situ grown on nickel foam by controlling the Mn doping level (similar to 6% atomic) and occupied site (3a site only). XRD, EXAFS and DFT calculations have been employed to confirm that the modified electronic configuration due to Mn doping induces local contraction of metal-O/metal bond length and increases curve degree within ab planes, which further introduces special stacking fault disorder between layers to stabilize the structure. Finally, the suitable-dose Mn doped NiMn-LDH exhibits high capacity (1498 C g(-1) at 2 A g(-1)), excellent rate capability and superior cycling performance (almost 100% capacity retention after 30,000 cycles at 50 A g(-1)). This work demonstrates modulating local environment by suitable dose of metal doping can boost the cycling performance of nickel-based electrode materials for applications in energy storage and conversion.

Automated summary

The study proposed a strategy to improve the cycling performance of Mn-doped NiMn-LDH by controlling the Mn doping level and occupied site, effectively modulating the electronic configuration and layer stacking mode to stabilize the structure. This resulted in high capacity, excellent rate capability, and superior cycling performance, demonstrating the potential for modulation of local environment to enhance the cycling performance of nickel-based electrode materials for energy storage and conversion applications.