Article ID | Journal | Published Year | Pages | File Type |
---|---|---|---|---|
1609162 | Journal of Alloys and Compounds | 2015 | 8 Pages |
Abstract
High Mn content multicomponent olivine phosphate LiMn0.9Fe0.1âxCoxPO4/C (x = 0, 0.05 and 0.1) are synthesized by two-step solid-state method and characterized by X-ray powder diffraction, FTIR spectra, XPS, electron microscopy and electrochemical measurements. Upon substitution, the cell volume decrease as a result of the smaller ionic radii of Fe2+ and Co2+ compared to Mn2+. Structural analysis demonstrates that Fe and/or Co substitution decrease the Mn-O and P-O bond length and increase the Li-O bond length, leading to enhanced physical stability and expanded Li diffusion channels. The Fe2+ and/or Co2+ substituted LiMnPO4 is found to have improved kinetics, lithium storage performance, and electronic conductivity during electrochemical reaction. In particular, LiMn0.9Fe0.05Co0.05PO4/C delivers a capacity of 145 mA h gâ1 at a current of 0.05 C and exhibits enhanced capacity retention compared to that of unmodified LiMnPO4/C. The enhanced electrochemical performance of co-substituted LiMnPO4 is attributed to the enhanced physical stability, the favorable delithiation/lithiation induced by previous redox reaction of Fe2+/Fe3+and Co2+/Co3+ and the improved electric/ionic transport properties.
Related Topics
Physical Sciences and Engineering
Materials Science
Metals and Alloys
Authors
Wei Xiang, Yanjun Zhong, Yan Tang, Huihui Shen, Enhui Wang, Heng Liu, Benhe Zhong, Xiaodong Guo,