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Sol–Gel Synthesis of Aliovalent Vanadium-Doped LiNi0.5Mn1.5O4 Cathodes with Excellent Performance at High Temperatures

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Abstract

Extraordinary performance at elevated temperature is achieved for high-voltage spinel-phase LiNi0.5Mn1.5O4 cathodes prepared using an adipic-acid-assisted sol–gel technique and doped with vanadium. V-substitution in the Li sites (Wykoff position 8a) is confirmed by V K-edge X-ray absorption spectroscopy and Rietveld refinement (Li0.995V0.005Ni0.5Mn1.5O4). V-doped LiNi0.5Mn1.5O4 delivered a reversible capacity of approximately 130 and 142 mAh g−1 at ambient and elevated temperature conditions, respectively. Furthermore, the Li0.995V0.005Ni0.5Mn1.5O4 phase rendered approximately 94 % and 84 % of initial capacity compared to approximately 85 % and 3 % for the LiNi0.5Mn1.5O4 phase after 100 cycles in ambient and elevated temperature conditions, respectively. The enhancements are mainly because of the suppression of Mn dissolution and unwanted side reaction with electrolyte counterpart, and to the increase in conductivity, improving the electrochemical profiles for the V-doped phase.

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