Ma Xiangdong, Ji Chuang, Yu Xiaoyuan, Liu Yike, Xiong Xunhui
Guangzhou Key Laboratory of Surface Chemistry of Energy Materials, New Energy Research Institute, School of Environment and Energy, South China University of Technology, Guangzhou 510006, P.R. China.
Key Laboratory for Biobased Materials and Energy of Ministry of Education, College of Materials and Energy, South China Agricultural University, Guangzhou, Guangdong 510642, China.
ACS Appl Mater Interfaces. 2021 Nov 17;13(45):53965-53973. doi: 10.1021/acsami.1c16730. Epub 2021 Nov 5.
Transition-metal phosphides (TMPs) anodes for lithium ion batteries (LIBs) usually show poor rate capability and rapid capacity degradation owing to their low electronic conductivities, huge volumetric changes, as well as inferior reversibility of the discharge product LiP. Herein, a covalent heterostructure with TMPs quantum dots anchored in N, P co-doped carbon nanocapsules (NPC) has been prepared in which the P element in TMPs is simultaneously doped into the carbon matrix. As a proof of concept, CoP quantum dots covalently anchored in NPC (CoP QDs/NPC) is prepared and evaluated as an anode for LIBs. The CoP QDs/NPC electrode not only demonstrates a high capacity and an extraordinary rate performance but also delivers an impressive cyclability with a high capacity retention of 102.5% after 1600 cycles, one of the best reported values for TMPs-based electrode materials for LIBs. The covalent heterostructure can facilitate the electron/ion transfer and maintain the structural stability during the intensive cycles. Moreover, density functional theory calculations demonstrate that the interfacial covalent coupling can enhance the electrochemical reversibility of the discharge product LiP in the charge processes lowering the conversion reaction energies. This work presents an effective interfacial engineering strategy for developing high-performance TMPs anodes for advanced LIBs.
用于锂离子电池（LIBs）的过渡金属磷化物（TMPs）阳极通常表现出较差的倍率性能和快速的容量衰减，这归因于其低电子电导率、巨大的体积变化以及放电产物LiP的较差可逆性。在此，制备了一种共价异质结构，其中TMPs量子点锚定在N、P共掺杂的碳纳米胶囊（NPC）中，TMPs中的P元素同时掺杂到碳基质中。作为概念验证，制备了共价锚定在NPC中的CoP量子点（CoP QDs/NPC）并将其评估为LIBs的阳极。CoP QDs/NPC电极不仅展现出高容量和出色的倍率性能，还具有令人印象深刻的循环稳定性，在1600次循环后容量保持率高达102.5%，这是基于TMPs的LIBs电极材料所报道的最佳值之一。这种共价异质结构可以促进电子/离子转移，并在密集循环过程中保持结构稳定性。此外，密度泛函理论计算表明，界面共价耦合可以增强充电过程中放电产物LiP的电化学可逆性，降低转化反应能量。这项工作提出了一种有效的界面工程策略，用于开发用于先进LIBs的高性能TMPs阳极。
