High-performance zinc-ion batteries enabled by electrochemically induced transformation of vanadium oxide cathodes

• 作者: Yang Li Wang Yang Wu Yang Yongfeng Huang Guoxiu Wang Chengjun Xu Feiyu Kang Liubing Dong
• 来源期刊: 能源化学
• 年，卷（期）: 2021,（9）
• 页码范围: 233-240
• 页数: 8页
• 语种: 英文

摘要

Rechargeable aqueous zinc-ion batteries(ZIBs)have become a research hotspot in recent years,due to their huge potential for high-energy,fast-rate,safe and low-cost energy storage.To realize good electro-chemical properties of ZIBs,cathode materials with prominent Zn2+ storage capability are highly needed.Herein,we report a promising ZIB cathode material based on electrochemically induced transformation of vanadium oxides.Specifically,K2V6O16·1.5H2O nanofibers were synthesized through a simple stirring method at near room temperature and then used as cathode materials for ZIBs in different electrolytes.The cathode presented superior Zn2+ storage capability in Zn(OTf)2 aqueous electrolyte,including high capacity of 321 mAh/g,fast charge/discharge ability(96 mAh/g delivered in 35 s),high energy density of 235 Wh/kg and good cycling performance.Mechanism analysis evidenced that in Zn(OTf)2 electrolyte,Zn2+ intercalation in the first discharge process promoted K2V6O16·1.5H2O nanofibers to transform into Zn3+ xV2O7(OH)2·2H2O nanoflakes,and the latter served as the Zn2+ -storage host in subsequent charge/dis-charge processes.Benefiting from open-framework crystal structure and sufficiently exposed surface,the Zn3+ xV2O7(OH)2·2H2O nanoflakes exhibited high Zn2+ diffusion coefficient,smaller charge-transfer resis-tance and good reversibility of Zn2+ intercalation/de-intercalation,thus leading to superior electrochem-ical performance.While in ZnSO4 aqueous electrolyte,the cathode material cannot sufficiently transform into Zn3+ xV2O7(OH)2·2H2O,thereby corresponding to inferior electrochemical behaviors.Underlying mechanism and influencing factors of such a transformation phenomenon was also explored.This work not only reports a high-performance ZIB cathode material based on electrochemically induced transfor-mation of vanadium oxides,but also provides new insights into Zn2+ -storage electrochemistry.