High performance of HNaV_(6)O_(16)·4H2_(O) nanobelts for aqueous zinc-ion batteries with in-situ phase transformation by Zn(CF_(3)SO_(3))_(2) electrolyte

摘要

Zn(CF_(3)SO_(3))_(2)as an electrolyte has been widely used to improve the electrochemical performance for ZIBs due to that the bulky CF_(3)SO_(3)-can reduce the solvation effect of Zn^(2+)and promote the ionic diffusion.Herein,we found that Zn(CF_(3)SO_(3))_(2)electrolyte can induce different electrochemical mechanisms from ZnSO_(4)electrolyte.Compared to the ZnSO^(4)electrolyte,the HNaV_(6)O_(16)·4H2_(O)electrode with Zn(CF_(3)SO_(3))_(2)electrolyte exhibits a high capacity of 444 mAh·g^(-1)at 500 mA·g^(-1)with a capacity retention of 92.3%after 80 cycles.Even,at a high rate of 5 Ag-1,the HNaV_(6)O_(16)·4H_(2)O electrode delivers an initial discharge capacity of 328 mAh·g^(-1)with a capacity retention of 93.7%after 1000 cycles.Differing from the mechanism with ZnSO4 electrolyte,the excellent cycle stability of HNaV_(6)O_(16)·4H_(2)Oelectrode can be attributed to the in-situ phase transformation to ZnxV_(2)O_(5)·nH_(2)O based on the co-intercalation of Zn^(2+)/H^(+).