Achieving Both High Voltage and High Capacity in Aqueous Zinc‐Ion Battery for Record High Energy Density

In this work, a high‐voltage output and long‐lifespan zinc/vanadium oxide bronze battery using a Co 0.247 V 2 O 5 ⋅0.944H 2 O nanobelt is developed. The high crystal architecture could enable fast and reversible Zn 2+ intercalation/deintercalation at highly operational voltages. The developed battery exhibits a high voltage of 1.7 V and delivers a high capacity of 432 mAh g −1 at 0.1 A g −1 . The capacity at voltages above 1.0 V reaches 227 mAh g −1 , which is 52.54% of the total capacity and higher than the values of all previously reported Zn/vanadium oxide batteries. Further study reveals that, compared with the pristine vanadium oxide bronze, the absorption energy for Zn 2+ increases from 1.85 to 2.24 eV by cobalt ion intercalation. Furthermore, it also shows a high rate capability (163 mAh g −1 even at 10 A g −1 ) and extraordinary lifespan over 7500 cycles, with a capacity retention of 90.26%. These performances far exceed those for all reported zinc/vanadium oxide bronze batteries. Subsequently, a nondrying and antifreezing tough flexible battery with a high energy density of 432 Wh kg −1 at 0.1 A g −1 is constructed, and it reveals excellent drying and freezing tolerance. This research represents a substantial advancement in vanadium materials for various battery applications, achieving both a high discharge voltage and high capacity.