Ti at the oxidation states of Ti3+ and Ti4+, was used to enhance the performance of Na3V2(PO4)2F2O by partially substituting vanadium. After doping Ti, the crystallographic volume is decreased due to the less radii of Ti3+/4+, and the valence of Ti is demonstrated identical to V. During sodium insertion in Ti-doped Na3V2(PO4)2F2O, the two discharge plateaus split into three because of the rearrangement of local redox environment. Consequently, the optimized Na3V0.96Ti0.04(PO4)2F2O shows a specific capacity of 123 and 63 mA·h/g at 0.1C and 20C, respectively. After 350 cycles at 0.5C, the capacity is gradually reduced corresponding to a retention of 71.05%. The significantly improved performance is attributed to the rapid electrochemical kinetics, and showcases the strategy of replacing V3+/4+ with Ti3+/4+ for high-performance vanadium-based oxyfluorophosphates.
孙孝飞,Anastase NDAHIMANA,王凌志,王子康,李泉省,唐 伟,杨敏行,梅雪松
. Improved rate and cycling performances of Na3V2(PO4)2F2O by Ti3+/4+ doping with two oxidation states for sodium cathodes[J]. Transactions of Nonferrous Metals Society of China, 2025
, 35(1)
: 243
-256
.
DOI: 10.1016/S1003-6326(24)66677-X