摘要
MAX phases are gaining attention as precursors of two-dimensional MXenes that are intensively pursued in applications for electrochemical energy storage.Here,we report the preparation of V_(2)SnC MAX phase by the molten salt method.V_(2)SnC is investigated as a lithium storage anode,showing a high gravimetric capacity of 490 mAh g−1 and volumetric capacity of 570 mAh cm^(−3) as well as superior rate performance of 95 mAh g^(−1)(110 mAh cm^(−3))at 50 C,surpassing the ever-reported performance of MAX phase anodes.Sup-ported by operando X-ray diffraction and density functional theory,a charge storage mechanism with dual redox reaction is proposed with a Sn-Li(de)alloying reaction that occurs at the edge sites of V_(2)SnC particles where Sn atoms are exposed to the electrolyte followed by a redox reaction that occurs at V_(2)C layers with Li.This study offers promise of using MAX phases with M-site and A-site elements that are redox active as high-rate lithium storage materials.
基金
supported by the National Natural Science Foundation of China(Grants No.51902215,91426304,21671195,21805295,51902320,51902319,21875271,and U2004212)
the China Postdoctoral Science Foundation(Grant No.2020M680082)
the International Partnership Program of Chinese Academy of Sciences(Grants 174433KYSB20190019)
the Leading Innovative and Entrepreneur Team Introduction Program of Zhejiang(Grant No.2019R01003)
the Ningbo top-talent team program for financial support
support from the Swedish Government Strategic Research Area in Materials Science on Functional Materials at Link?ping University(Faculty Grant SFO Mat LiU No.200900971)
support of the electron microscopy laboratory in Link?ping(Grant KAW 2015.0043)
an Academy Fellow Grant(P.E.,2020.0196)
the Swedish Foundation for Strategic Research(SSF)through project funding(EM16-0004)
a Research Infrastructure Fellow Grant(RIF 14-0074)。
