Pan Qianfeng, Zheng Fenghua, Deng Dingfei, Chen Bo, Wang Yang
School of Chemical Engineering and Technology, Tianjin University, Tianjin 300350, China.
Department of Mechanical Engineering, University of Maryland, College Park, Maryland 20742, United States.
ACS Appl Mater Interfaces. 2021 Dec 1;13(47):56692-56703. doi: 10.1021/acsami.1c19320. Epub 2021 Nov 17.
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 at 1 A g (690 C g without Ac anions), an outstanding rate capability of 72.5% at 30 A g, 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.
基于过渡金属的层状双氢氧化物（LDHs）因其优异的电化学活性和可调节的化学成分，作为有前景的功能纳米材料受到了广泛研究。在本工作中，以醋酸根阴离子（Ac）作为插层元素，通过简单的水热法制备了不同醋酸根阴离子插层量或水热溶液体积的、排列在泡沫镍上的NiCo-LDH纳米片阵列。优化后的醋酸根阴离子量将LDH纳米片的层间距从0.8 nm扩大到了0.94 nm。在1 A g下具有1200 C g的超高比容量（无醋酸根阴离子时为690 C g）、在30 A g下具有72.5%的出色倍率性能以及在4500次循环后具有79.90%的循环稳定性，这些主要归因于醋酸根阴离子插层带来的更大层间距。扩大的层间距有利于稳定LDHs的α相，并加速电化学反应中的电子传输和电解质渗透。这项工作揭示了NiCo-LDH纳米片层间距调控的机制，并通过整合其独特的层状结构和层间阴离子交换特性，为合成具有优异电化学性能的功能纳米材料提供了一种有前景的策略。
