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 alpha-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.

Automated summary

In this study, the use of Ac- anions for intercalation effectively expanded the interlayer space of NiCo-LDH nanosheets, leading to significantly enhanced electrochemical performance. This provides a promising strategy for synthesizing functional nanomaterials with excellent electrochemical properties by regulating the interlayer spacing with intercalated anions.