Enhancement of Electrochemical Properties of SIBs by Generating a New Phase in Potassium-Doped NaV6O15 Film Electrodes

Potassium-doped NaV6O15 thin films have been grown on fluorine-doped tin oxide (FTO) conductive glass using a simple low-temperature liquid-phase deposition method and through the annealing process. X-ray photoelectron spectroscopy revealed that potassium ions were successfully doped in NaV6O15 thin...

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Veröffentlicht in:Journal of physical chemistry. C 2022-05, Vol.126 (19), p.8208-8217
Hauptverfasser: Xu, Haiyan, Liu, Fanglin, Li, Dongcai, Ruan, Junhai, Wang, Aiguo, Sun, Daosheng
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Sprache:eng
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Zusammenfassung:Potassium-doped NaV6O15 thin films have been grown on fluorine-doped tin oxide (FTO) conductive glass using a simple low-temperature liquid-phase deposition method and through the annealing process. X-ray photoelectron spectroscopy revealed that potassium ions were successfully doped in NaV6O15 thin films. The kinetics analysis based on cyclic voltammetry measurements showed that the doped potassium ions enhanced the Na+ intercalation behavior and induced the formation of a new phase. Moreover, high-resolution transmission electron microscopy further verified the formation of the new phase. The annealed doped films exhibited excellent structural stability during cycling. With these benefits, the capacities of the film electrodes annealed at 400 and 450 °C were maintained to be 83.24 and 188.16% after 100 cycles, respectively. The surprising capacity growth of the doped film annealed at 450 °C can be attributed to the phase transition from NaV6O15 to NaV3O8. The discharge–charges profiles further showed that the capacity first increased and then decreased during the charging/discharging process. Also, the chronoamperometry curve test revealed that the Na+ transference number of the NaClO4/PC electrolyte was 0.077. Due to the synergistic effect of NaV3O8 and NaV6O15, the film showed capacity growth instead of capacity fading. It is the doped potassium ions that prevent the structural collapse, ensuring that the phase transition can be smoothly carried out during the cycles. Our research presents an effective way for improving electrode materials with a long cycle life.
ISSN:1932-7447
1932-7455
DOI:10.1021/acs.jpcc.1c10613