Electrochemical activation of Ni-based layered double hydroxides via host layer oxidation-induced conductivity enhancement

Abstract Compared with lithium-ion batteries that use flammable organic solvents, aqueous batteries are safer, but they often suffer from short cycle life due to dissolution–precipitation reactions of active materials. To overcome this limitation, we investigated layered double hydroxides (LDHs), which undergo intercalation-type reactions. Although LDHs have been reported as battery-active materials, their detailed mechanism remains unclear. Our study revealed that pristine LDHs exhibit large irreversible capacity and insufficient charge–discharge performance. After electrochemical oxidation treatment compensated for this irreversible capacity, a stable cycling capacity was achieved. Conductivity increased by more than an order of magnitude after oxidation, suggesting that holes were induced within the crystal. We conclude that oxidation treatment is crucial for the practical utilization of LDHs as active materials.