Disordered Lithium-Rich Oxyfluoride as a Stable Host for Enhanced Li + Intercalation Storage (original) (raw)

rock-salt structures, with Li + /TM evenly sharing cation sites and close-packed anion arrays, may be a reasonable alternative for effi cient Li + storage. After Li + extraction, the TM may remain at the cation sublattice sites and uphold well the disordered rocksalt framework. A recent work based on ab initio computations revealed that Li + transport can be facile in a disordered cubic rock-salt oxide (Li 1.211 Mo 0.467 Cr 0.3 O 2 ) with Li-excess. [ 8 ] It was found that such framework is stable with a maximum of 45% of the cation sites vacant. Herein, we demonstrate that a new dilithium disordered rock-salt Li 2 VO 2 F intercalation material can deliver up to about 1.8 Li + capacity per TM (420 mAh g −1 ) at ≈2.5 V (1000 Wh kg −1 ) with only minor lattice volume change (≈3%). Such material with mixed O 2− /F − anion environment has been synthesized by a simple ball-milling method. The two Li + storage with V 3+ /V 5+ redox reactions (Li 2 VO 2 F ↔ 2 Li + + 2e − + VO 2 F) leads to an attractively high theoretical capacity of 462 mAh g −1 . Moreover, Li 2 VO 2 F shows good capacity retention and minor increase in polarization upon fast charging/discharging or upon low-temperature operation.