Metal Oxides with Distinctive Valence States in an Electron‐Rich Matrix Enable Stable High‐Capacity Anodes for Li Ion Batteries. Issue 2 (27th November 2019)

• Record Type: Journal Article
• Authors: Liu, Jipeng; Dong, Liwei; Chen, Dongjiang; Han, Yupei; Liang, Yifang; Yang, Mengqiu; Han, Jiecai; Yang, Chunhui; He, Weidong
• Is Part Of: Small methods. Volume 4:Issue 2(2020)
• Page Start: n/a
• Page End: n/a
• Publication Date: 2019-11-27
• Subjects: lithium ion batteries -- MoOx/NCNTs -- oxide anodes -- pyrolysis methods -- valence states; Nanotechnology -- Methodology -- Periodicals; Nanotechnology -- Periodicals; Periodicals; 620.5028
• DOI: 10.1002/smtd.201900753
• Languages: English
• ISSNs: 2366-9608

Abstract

Abstract: Metal oxides are arguably a promising solution to next‐generation high‐energy‐density anode materials. In particular, molybdenum oxides own high theoretical specific capacity (1117 and 838 mA h g −1 for MoO3 and MoO2, respectively), high chemical stability, and low cost. The low electronic conductivity of MoO3 limits their charge–discharge rate performances and delithiation capability. By controlling the valence state of MoO x with carbon, partial MoO3 can be reduced to MoO2 with low electrical resistance and high‐rate capacity. Nonetheless, both molybdenum oxides undergo large‐volume expansion/shrinkage and even pulverization in the lithiation/delithiation process. Herein, through a facile pyrolysis method a MoO x /N‐doped carbon nanotube (NCNT) anode with controllable valence states of Mo is designed. The high conductivity and flexibility of the NCNT matrix form a stable MoO2 /MoO3 anode with finely matched lattices and coordinated 3d electrons. Owing to molecularly close contact between electron‐rich CNTs and MoO x, MoO x /NCNTs own a high conductivity of 0.36 S cm −1, and mitigate the volume expansion in charges and discharges. The MoO3 /MoO2 /NCNTs anode delivers an unparalleled high gravimetric capacity of 970 mA h g −1, over 100‐cycle stability and high rate capability. Abstract : MoO x /N‐doped carbon nanotubes (NCNTs) anodes are synthesized through pyrolysis, owning a high conductivity (0.36 S cm −1 ) and unparalleled cycle stability. In situ Raman and density‐functional‐theory calculation are employed to assess the electrochemical reaction mechanism and confirm strong adsorption between NCNTs and MoO x . This method has the potential for the practical applications of double‐oxide anodes in electron‐rich matrices in high‐performance lithium ion batteries.