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

Abstract

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.

Hierarchical Nanocages Assembled by NiCo-Layered Double Hydroxide Nanosheets for a High-Performance Hybrid Supercapacitor

“…Similarly, Pan et al investigated systematically the effect of acetate anions (Ac – ) on interlayer spacing of NiCo-LDH nanosheets. The optimal product (NaAc10-LDH) delivered an ultrahigh specific capacity of 1200 C g –1 at 1 A g –1 . Another feasible tactic is to rationally design the LDH-based hybrid nanoarchitectures with other well-known electrode materials of high specific capacitance and good conductivity, thus overcoming the inherent defect of low electrical conductivity.…”

“…The optimal product (NaAc10-LDH) delivered an ultrahigh specific capacity of 1200 C g −1 at 1 A g −1 . 15 Another feasible tactic is to rationally design the LDH-based hybrid nanoarchitectures with other well-known electrode materials of high specific capacitance and good conductivity, thus overcoming the inherent defect of low electrical conductivity. Zhang et al fabricated NiMn-LDH/MXene hybrid composites by the in situ crystallization process, and the NiMn-LDH/MXene hybrid composite with an optimized ratio of 2:1 showed a high specific capacitance of 1575 F g −1 at 0.5 A g −1 and impressive cycling stability (90.3% of initial capacitance after 10,000 cycles at 5 A g −1 ).…”

Hierarchical pipe cactus-like Ni/NiCo-LDH core–shell nanotube networks as a self-supported battery-type electrode for supercapacitors with high volumetric energy density

“…The employed deposition time represents a compromise between a high amount of NiCo-LDH as redox-active material to boost the energy density while keeping the porous structure of the catalyst with its torturous pathways free from clogging, 35 which facilitates the accessibility of the electrolyte to the active sites on the tubes, resulting in a great contribution to the reversible and fast faradaic reactions and an enhanced capacity of the electrode. 51,52 The successful incorporation of NiCo-LDH was further conrmed by EDX measurements performed on the large area lateral view of the as-prepared Ni-NTNW and NiCo-LDH@Ni-NTNW as shown in Fig. 2c and f, respectively.…”

Anion‐cation double‐substitution endows iron sulfide with remarkably enhanced specific capacity and rate performance as anode for supercapacitors

“…Figure S12A shows the CV curves of NiCo‐LDH/G electrode at diverse scan rates from 5 to 25 mV s −1 with congruent shapes and exhibits obvious redox peaks within −0.1 to 0.45 V (vs. Ag/AgCl), indicating the fast and reversible redox reactions generated by nickel and cobalt elements. The redox reaction is based on the following equations: 47–49 …”