A flexible carbon nanotube@V2O5 film as a high-capacity and durable cathode for zinc ion batteries

Abstract Aqueous zinc-ion batteries (ZIBs) are receiving a continuously increasing attention for mobile devices, especially for the flexible and wearable electronics, due to their non-toxicity, non-flammability, and low-cost features. Despite the significant progress in achieving higher capacities for electrode materials of ZIBs, to endow them with high flexibility and economic feasibility is, however, still a significant challenge remaining unsolved. Herein, we present a highly flexible composite film composed of carbon nanotube film and V2O5 (CNTF@V2O5) with high strength and high conductivity, which is prepared by simply impregnating a porous CNT film with an aqueous V2O5 sol under vacuum. For this material, intimate incorporation between V2O5 and CNTs has been achieved, successfully integrating the high zinc ion storage capability with high mechanical flexibility. As a result, this CNTF@V2O5 film delivers a high capacity of 356.6 mAh g−1 at 0.4 A g−1 and excellent cycling stability with 80.1% capacity retention after 500 cycles at 2.0 A g−1. The novel strategy and the outstanding battery performance presented in this work should shed light on the development of high-performance and flexible ZIBs.