KxV2O5 with excellent electrochemical properties can be used as an excellent cathode material for aqueous zinc-ion batteries,and its controllable synthesisis especially important.In this study,the effects of the molar ratio of oxalic acid(C2H2O4·2H2O)to vanadium pentoxide(V2O5)on the structure,morphology and electrochemical properties of potassium vanadate(K0.486 V2O5)cathodes were investigated.The controllable preparation of K0.486 V2O5 was achieved.The results show that when the molar ratio of C2H2O4·2H2O/V2O5 is about 5:2,potassium vanadate has higher crystallinityandmore regularnanorod-likemorphology.The distinct pseudocapacitive effect endows it with excellent rate performance and outstanding kinetic characteristics,showing high capacity and good cycling stability.At current densities of 0.1,0.2,0.5,1,2,5 and 10 A·g-1,the discharge specific capacities are 395.3,366.9,323.4,283.5,247.7,181.8 and 127.3 mAh·g-1,respectively.At a high current density of 5 A·g-1,it still delivers a reversible capacity of 196.5 mAh·g-1 after 2 000 cycles with an ultrahigh capacity retention rate of 127.9%.The energy storage process of K0.486 V2O5 is controlled by ion diffusion process and surface capacitance behavior.With the increase of the scanning rate,the storage of Zn2+is mainly controlled by the capacitive behavior.The significant pseudocapacitance effect is the key factor to obtaining excellent rate performance and eminentkinetic behavior.
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维普
