Cheng Wenbo, Wan Biao, Xu Shishuai, Zhang Miaoxin, Zeng Rongguang, Liu Zexin, Zhang Chengwei, Yin Fuxing, Wang Gongkai, Gou Huiyang
Center for High Pressure Science and Technology Advanced Research, Beijing 100094, China.
School of Material Science and Engineering, Research Institute for Energy Equipment Materials, Hebei University of Technology, Tianjin 300130, China.
ACS Appl Mater Interfaces. 2020 Jul 1;12(26):29218-29227. doi: 10.1021/acsami.0c04963. Epub 2020 Jun 16.
Performance degradation of lithium/sodium-ion capacitors (LICs/SICs) mainly originates from anode pulverization, particularly the alloying and conversion types, and has spurred research for alternatives with an insertion mechanism. Three-dimensional (3D) topotactic host materials remain much unexplored compared to two-dimensional (2D) ones (graphite, .). Herein, vanadium monophosphide (VP) is designed as a 3D topotactic host anode. electrochemical characterizations reveal that there are no phase changes during (de)intercalation, which follows the topotactic intercalation mechanism. Computational simulations also confirm the metallic feature and topotactic structure of VP with a spacious interstitial position for the accommodation of guest species. To boost the electrochemical performance, carbon nano-onions (CNOs) are coupled with 3D VP. Superior specific capacity and rate capability of VP-CNOs lithium/sodium can be delivered due to the fast ion diffusion nature. An exceptional capacity retention of above 86% is maintained after 20 000 cycles, benefitting from the topotactic intercalation process. The optimized LICs/SICs exhibit high energy/power densities and an ultrastable lifespan of 20 000 cycles, which outperform most of the state-of-the-art LICs and SICs, demonstrating the potential of VP-CNOs as insertion anodes. This exploration would draw attention with regard to insertion anodes with 3D topotactic host topology and provide new insights into anode selection for LICs/SICs.
锂/钠离子电容器（LICs/SICs）的性能退化主要源于阳极粉化，尤其是合金化和转化型阳极粉化，这推动了对具有嵌入机制的替代材料的研究。与二维（2D）主体材料（如石墨等）相比，三维（3D）拓扑主体材料的研究仍较少。在此，单磷化钒（VP）被设计为一种3D拓扑主体阳极。电化学表征表明，在（脱）嵌入过程中没有相变，这遵循拓扑嵌入机制。计算模拟也证实了VP的金属特性和拓扑结构，其具有宽敞的间隙位置以容纳客体物种。为了提高电化学性能，将碳纳米洋葱（CNOs）与3D VP耦合。由于快速的离子扩散特性，VP-CNOs对锂/钠具有优异的比容量和倍率性能。在20000次循环后，得益于拓扑嵌入过程，仍保持超过86%的出色容量保持率。优化后的LICs/SICs表现出高能量/功率密度和20000次循环的超稳定寿命，优于大多数现有技术的LICs和SICs，证明了VP-CNOs作为嵌入阳极的潜力。这一探索将引起人们对具有3D拓扑主体结构的嵌入阳极的关注，并为LICs/SICs的阳极选择提供新的见解。
