Ordered-Vacancy-Induced Cation Intercalation into Layered Double Hydroxides: A General Approach for High-Performance Supercapacitors

New types of cation storage materials would show tremendous potential in the development of high-performance rechargeable energy storage devices. Herein, we develop layered double hydroxides (LDHs) as promising cation supercapacitor materials in aqueous and neutral operation, via an effective electrochemical activation strategy, for a reversible intercalation of a wide range of metal cations. These activated LDH materials exhibit overwhelming metal-ion storage capacities in aqueous electrolytes as a result of the phase transformation of LDH (repulsive to cations) to hydrogen-vacancy-enriched LDH (LDH-HV, attractive to cations) induced by the electrochemical activation process. The activated LDH-HV phase provides a two-dimensional open channel with abundant active sites (HV) for a reversible intercalation of metal ions, accounting for the significantly enhanced energy storage performance. This vacancy-induced cation intercalation into LDHs builds up a general approach for developing earth-abundant transition-metal resources as a prospective energy storage material toward a large variety of cation supercapacitors.