Novel Dilithium Metal Oxyfluoride As High Capacity Intercalation Cathode Material for Li-Ion Batteries
Recently, we developed a new disordered dilithium metal oxyfluoride of Li2VO2F [3-4]. The novel material exhibits outstandingly high capacity of 420 mAh g-1 with small lattice change of only 3% owing to its stable rock-salt host structure. Lithium, occupying 2/3 of the cation sites, is highly mobile [5-6]. Compared to the redox of V3+/5+ at ~2.5 V, the chromium substitution into Li2VO2F leads to increased discharge voltages (accordingly higher energy density) and better cyclic stability. Moreover, nearly 1.8 Li+are accessible and can be reversibly stored at a current rate of ~ C/35 and room temperature . Various characterization techniques were applied to verify the redox process and reversible structural change upon electrochemical cycling. The novel dilithium oxyfluoride intercalation material with disordered rock-salt structure opens new possibilities for obtaining higher storage capabilities for LIBs.
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