In‐Situ Electrochemically Activated Surface Vanadium Valence in V2C MXene to Achieve High Capacity and Superior Rate Performance for Zn‐Ion Batteries. (4th December 2020)

• Record Type: Journal Article
• Authors: Liu, Ying; Jiang, Yue; Hu, Zhe; Peng, Jian; Lai, Weihong; Wu, Dianlun; Zuo, Shouwei; Zhang, Jing; Chen, Bin; Dai, Ziwen; Yang, Yingguo; Huang, Yang; Zhang, Wei; Zhao, Wei; Zhang, Wang; Wang, Lei; Chou, Shulei
• Is Part Of: Advanced functional materials. Volume 31:Number 8(2021)
• Page Start: n/a
• Page End: n/a
• Publication Date: 2020-12-04
• Subjects: electrochemical activation -- high‐valence V -- V 2C MXenes -- V‐C‐V structure -- Zn‐ion batteries; Materials -- Periodicals; Chemical vapor deposition -- Periodicals; 620.11
• DOI: 10.1002/adfm.202008033
• Languages: English
• ISSNs: 1616-301X

Abstract

Abstract: Vanadium‐based materials are fascinating potential cathodes for high energy density Zn‐ion batteries (ZIBs), due to their high capacity arising from multi‐electron redox chemistry. Most vanadium‐based materials suffer from poor rate capability, however, owing to their low conductivity and large dimension. Here, we propose the application of V2 C MXene (V2 CT x ), a conductive 2D nanomaterial, for achieving high energy density ZIBs with superior rate capability. Through an initial charging activation, the valence of surface vanadium in V2 CT x cathode is raised significantly from V 2+ /V 3+ to V 4+ /V 5+, forming a nanoscale vanadium oxide (VO x ) coating that effectively undergoes multi‐electron reactions, whereas the inner V‐C‐V 2D multi‐layers of V2 CT x are intentionally preserved, providing abundant nanochannels with intrinsic high conductivity. Owing to the synergistic effects between the outer high‐valence VO x and inner conductive V‐C‐V, the activated V2 CT x presents an ultrahigh rate performance, reaching 358 mAh g −1 at 30 A g −1, together with remarkable energy and power density (318 Wh kg −1 /22.5 kW kg −1 ). The structural advantages of activated V2 CT x are maintained after 2000 cycles, offering excellent stability with nearly 100% Coulombic efficiency. This work provides key insights into the design of high‐performance cathode materials for advanced ZIBs. Abstract : An effective strategy to unleash the potential of V2 C MXene for fast Zn‐ion storage is developed via regulating the valence of surface vanadium while preserving the inner 2D conductive V‐C‐V layers, which forms a VO x /V2 CT x heterostructure. This heterostructure not only offers abundant active sites for Zn 2+ storage, but also provides ordered nanochannels for rapid electron/ion transfer.