FeVO4•nH2O@rGO nanocomposite as high performance cathode materials for aqueous Zn-ion batteries

Aqueous zinc ion batteries (ZIBs) have recently attracted an increasing attention as an environmental friendliness, low cost and highly potential novel energy storage system. Although vanadium-based materials serve as a capable of arousing and holding the attention cathode materials for ZIBs, whereas low conductivity and confusing zinc ion storage mechanisms remain an obstacle. Herein, FeVO4 center dot n-H2O@rGO composite is employed to evaluate zinc ion storage capability as a cathode for the first time in 2 M Zn(TFSI)(2) electrolyte. Benefiting from the large lattice spacing, dual electrochemical activity and fast electron transfer, the composite delivers excellent rate performance and long life cycle (the capacity retained similar to 100 mAh g(-1) at 1.0 A g(-1) after 1000 cycle). In addition, the electrochemical performance of graphene-modified FeVO4 center dot nH(2)O is superior to other precursors for comparison. Furthermore, the intercalated/de-intercalated mechanism of zinc ion is distinct from the traditional conversion reaction, which is confirmed by in-situ X-ray diffraction and various ex-situ techniques. (C) 2019 Elsevier B.V. All rights reserved.