High-performance Na1.25V3O8 nanosheets for aqueous zinc-ion battery by electrochemical induced de-sodium at high voltage

Aqueous rechargeable zinc-ion batteries(ARZIBs) are expected to replace organic electrolyte batteries owing to its low price,safe and environmentally friendly characteristics.Herein,we fabricated vanadium-based Na1.25V3O8 nanosheets as a cathode material for ARZIBs,which present a high performance by electrochemical de-sodium at high voltage to form Na2V6O16 phase in the first cycle:high capacity of 390 mAh/g at 0.1 A/g,high rate perfo rmance(162 mAh/g at 10 A/g) and superior cycle stability(179 mAh/g with a high capacity retention of 88.2% of the maximum capacity after 2000 cycles).In addition,the cell exhibits a high energy density of 416.9 Wh/kg at 143.6 W/kg,suggesting great potential of the as-prepared Na1.25V3O8 nanosheets for ARZIBs.

High-performance (NH_(4))_(2)V_(6)O_(16).0.9H_(2)O nanobelts modified with reduced graphene oxide for aqueous zinc ion batteries

Ammonium vanadate has been considered as a competitive high-performance cathode material for aqueous Zn-ion batteries.However,it still suffers from insufficient rate capability and poor cyclability due to the low electronic conductivity.Herein,(NH_(4))_(2)V_(6)O_(16).0.9H_(2)Onanobelts with reduced graphene oxide(RGO)modification are synthesized by one-step hydrothermal reaction.Benefiting from the addition of RGO,an excellent electrochemical performance of(NH_(4))_(2)V_(6)O_(16).0.9H_(2)O@RGO nanobelts can be obtained.The(NH_(4))_(2)V_(6)O_(16).0.9H_(2)O@RGO displays a high-rate capacity and a high energy density of 386 Wh/kg at 72 W/kg.In particular,after 1000 cycles at 5 A/g,the capacity remains at 322 mAh/g with 92.8%capacity retention.In addition,the key reaction mechanisms of reversible Zn^(2+)insertion/extraction in(NH_(4))_(2)V_(6)O_(16).0.9H_(2)O@RGO are clarified.