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Ultra‐long cycle life and high rate performance subglobose Na 3 V 2 ( PO 4 ) 2 F 3 @C cathode and its regulation
Author(s) -
Zhan Wenxing,
Fan Changling,
Zhang Weihua,
Yi Guodong,
Chen Han,
Han Shaochang,
Liu Jinshui
Publication year - 2020
Publication title -
international journal of energy research
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.808
H-Index - 95
eISSN - 1099-114X
pISSN - 0363-907X
DOI - 10.1002/er.5397
Subject(s) - ammonium bromide , cathode , materials science , electrochemistry , carbon fibers , chemical engineering , polyvinylidene fluoride , diffusion , nuclear chemistry , analytical chemistry (journal) , chemistry , electrode , chromatography , pulmonary surfactant , composite material , physics , composite number , engineering , thermodynamics , polymer
Summary A nitrogen‐doped carbon coated subglobose Na 3 V 2 (PO 4 ) 2 F 3 @C (NVPF) cathode for sodium‐ion batteries was synthesized by using hexadecyl trimethyl ammonium bromide (CTAB) as soft template and polyvinylidene fluoride (PVDF) as carbon source. CTAB plays a significant role on the formation of sphere micelles. Precursor ions are self‐assembled on the surface at appropriate concentration and its mechanism is investigated in subglobose NVPF@C‐4. CTAB also increases the conductivity of carbon layer as −(CH 3 ) 3 N + in CTAB is combined with residual carbon from PVDF to form partially N‐doped carbon. Meanwhile, the carbon source PVDF contributes to prevent the generation of impurity Na 3 V 2 (PO 4 ) 3 by compensating the evaporative fluorine. Generally, CTAB and PVDF play multifunctional roles in regulating Na 3 V 2 (PO 4 ) 2 F 3 @C cathode with well‐developed crystallite, high rate performance, good conductivity, and ultra‐long cycle life. The specific capacity of NVPF@C‐4 cathode at 0.1 C and 10 C is as high as 121.5 mAh·g −1 and 99.2 mAh·g −1 with high capacity retention of 90.1% even after 1000 cycles at 10 C. The excellent rate performance is also attributed to the high diffusion coefficient of Na + and high exchange current according to the kinetic analysis. The enhanced electrochemical performances reveal the special regulation in this paper is feasible to obtain excellent structural stability of NVPF materials.