Freestanding V5O12 · 6H2O‐CNTs composite films as cathode for foldable aqueous zinc‐ion batteries

Summary Advanced wearable portable electronic products are needed energy storage devices with foldable properties. Zinc‐ion batteries (ZIBs) are one of the most promising alternatives for energy storage devices due to their significant advantages, such as low cost, high reliability, and safety for folding. Herein, V5O12 · 6H2O (VOH) was obtained by facile electrodeposition strategy on carbon nanotube (CNTs) film, forming the freestanding V5O12 · 6H2O‐CNTs (VOH‐CNTs) composite films. The resultant VOH‐CNTs composite films with high mechanical properties can be directly used as the cathode for foldable aqueous zinc‐ion batteries (AZIBs). The VOH‐CNTs electrode at a current density of 1 A g−1 shows a high specific capacity of 356 mAh g−1 and the capacity retention of 96% after 500 cycles. Even a reversible specific capacity of 292 mAh g−1 can be achieved at a current density of 5 A g−1 and the capacity retention of 93% after 4000 cycles. A high coulombic efficiency stays nearly 100%. The electrochemical properties of the prepared cells measured in different folding states remain stable, indicating the devices are suitable for use as foldable energy storage devices. Freestanding V5O12 · 6H2O‐CNTs cathodes can be directly assembled into soft pack cells. When the soft pack battery was folded to different angles of 90°, 180° and returned to the initial state, the corresponding LED could still be lighted.