Binder-free CaV3O7 nanobelts with rich oxygen defects as high energy cathode for aqueous Zn-ion battery

The development of high-energy cathode for zinc-ion batteries (ZIBs) is highly attractive but a changeling. Herein, we demonstrate a kind of CaV3O7-x nanobelts with rich oxygen defects as new stable and robust cathode for aqueous Zn-ion battery, with high capacity and good electrochemical stability. The oxygen-deficient CaV3O7 nanobelts display an excellent gravimetric capacity of 471.04 mAh g−1 and areal capacitive of 2.26 mAh cm−2. In addition, a maximun energy density of 363.9 Wh kg−1 at a power density of 644.1 W kg−1 is also obtained for this as-fabricated aqueous battery based on the cathode materials. This battery also has a good durability with over 82% capacitance reservation after 400 cycles. Furthermore, a flexible and high-capacity quasi-solid-state battery with the CaV3O7-x as cathode presents an admirable energy density of 9.2 mWh cm−3. This work provides valuable ideas for designing other advanced cathode materials for electrochemical energy storage.