Interlayer Spacing Regulation of NiCo-LDH Nanosheets with Ultrahigh Specific Capacity for Battery-Type Supercapacitors

The transition metal-based layered double hydroxides (LDHs) have been extensively studied as promising functional nanomaterials owing to their excellent electrochemical activity and tunable chemical composition. In this work, using acetate anions (Ac–) as intercalating elements, the NiCo-LDH nanosheets arraying on Ni foam with different amounts of Ac– anion intercalation or volume of hydrothermal solution were prepared by a simple hydrothermal method. The optimized amount of Ac– anions expanded the interlayer space of LDH nanosheets from 0.8 to 0.94 nm. An ultrahigh specific capacity of 1200 C g–1 at 1 A g–1 (690 C g–1 without Ac– anions), an outstanding rate capability of 72.5% at 30 A g–1, and a cycle stability of 79.90% after 4500 cycles were mainly attributed to the higher interlayer spacing of Ac– anion intercalation. The enlarged interlayer spacing was beneficial for stabilizing the α-phase of LDHs and accelerating the electron transport and electrolyte penetration in the electrochemical reaction. This work sheds light on the mechanisms of the interlayer spacing regulation of NiCo-LDH nanosheets and offers a promising strategy to synthesize functional nanomaterials with excellent electrochemical performance via integrating their unique layered structure and interlayer anion exchange characteristics.