Structure, Composition, and Electrochemistry of Chromium-Substituted ε-LiVOPO 4. Lee, K., Siu, C., Hidalgo, M., F., V., Rana, J., Zuba, M., Chung, Y., Omenya, F., Piper, L., F., J., Liu, H., Chernova, N., A., & Whittingham, M., S. ACS Applied Energy Materials, 4(2):1421-1430, 2, 2021.
Structure, Composition, and Electrochemistry of Chromium-Substituted ε-LiVOPO 4 [pdf]Paper  Structure, Composition, and Electrochemistry of Chromium-Substituted ε-LiVOPO 4 [link]Website  doi  abstract   bibtex   9 downloads  
Lithium vanadyl phosphate (LiVOPO4) is an attractive cathode material for next-generation lithium-ion batteries, having the ability to reversibly intercalate two Li ions per transition metal redox center to reach a theoretical capacity of 305 mAh g-1. This material has a high energy density with two voltage plateaus of 2 and 4 V. However, reduced capacity retention at faster rates and sluggish kinetics in the high-voltage region leaves much room for improvement. Cr substitution was implemented to mitigate these limitations and enhance the electrochemical performance of ε-LiVOPO4. By various characterization techniques, we have established the composition of the hydrothermally synthesized Cr-substituted samples to be LixHyCrzV1-zOPO4 solid solution (0.80 ≤ x ≦ 0.85, 0.25 ≦ y ≦ 0.60, and z ≦ 0.05). All Cr-substituted samples demonstrated higher coulombic efficiency and superior cycling stability for over 40 cycles at C/15. Electrochemical tests show Cr substitution enhances the Li-ion diffusion in the high-voltage regime and the reaction reversibility of ε-LiVOPO4.

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