Dealloying-constructed hierarchical nanoporous bismuth-antimony anode for potassium ion batteries

• Published in: Fundamental research (Beijing) Vol. 1; no. 4; pp. 408 - 417
• Main Authors: Gao, Hui, Yin, Kuibo, Guo, Zhiyuan, Zhang, Ying, Ma, Wensheng, Yang, Wanfeng, Sun, Ke, Peng, Zhangquan, Zhang, Zhonghua
• Format: Journal Article
• Language: English
• Published: Elsevier B.V 01.07.2021; KeAi Communications Co. Ltd
• Subjects: Bismuth-antimony anodes; Dealloying; Density functional theory; Operando X-ray diffraction; Potassium ion battery; Density functional theory; Potassium ion battery; Dealloying; Bismuth-antimony anodes; Operando X-ray diffraction
• ISSN: 2667-3258; 2667-3258
• DOI: 10.1016/j.fmre.2021.06.001

Bi-Sb alloys are appealing anode materials for potassium ion batteries (PIBs) but challenged by their enormous volumetric variation during operation. Herein, a facile one-step dealloying protocol was devised and utilized to prepare the Bi-Sb alloys that manifest an exotic bicontinuous hierarchical nanoporous (np) microstructure ideal for volume-change mitigation and K+ transport percolation. The growth mechanism fostering the peculiar morphology of the np-(Bi,Sb) alloys was investigated and clarified via operando X-ray (XRD) and ex-situ scanning electron microscopy (SEM). In particular, the np-Bi6Sb2 electrode, optimized for comprehensive electrochemical performance, achieves decent reversible capacities and a superior lifespan, as benchmarked with the monometallic references and other Bi-Sb alloy electrodes. The (de)potassiation mechanism of the np-(Bi,Sb) alloys was studied by operando XRD and further rationalized by density functional theory (DFT) calculations, whereby a homogeneous (segregation-free) and robust two-step electrochemically-driven phase transformations’ catenation of (Bi,Sb) ↔ K(Bi,Sb)2 ↔ K3(Bi,Sb) was reliably established to substantiate the outstanding reversibility of the np-(Bi,Sb) anodes in PIBs.