Fabrication of an Inexpensive Hydrophilic Bridge on a Carbon Substrate and Loading Vanadium Sulfides for Flexible Aqueous Zinc-Ion Batteries

Coupling electrode materials with carbon substrates to construct flexible aqueous Zn-ion batteries (ZIBs) with excellent electrochemical performance is an attractive research focus. However, further improving the Zn²⁺/electron diffusion kinetics in such systems is still desirable. Herein, we present a novel hydrophilic carbon substrate that employs acid-treated natural halloysite and carbon nanotubes for the first time as structural and interfacial modifiers for loading V₃S₄ as a composite cathode (denoted as HCC-V₃S₄) for flexible ZIBs. The devices exhibit a high specific capacity of 148 mA h·g^–1 under a current density of 0.5 A·g^–1 (95% retention after 200 cycles), excellent rate performance, and a high energy density of 155.7 W h·kg^–1, together with a high-power density of 5000 W·kg^–1. The promising electrochemical property can be associated with the formation of the hydrophilic surface/interface and with the good conductivity of the composite electrode, which increases the Zn²⁺/electron transmission rate. Owing to the cost-effective design of the flexible substrate and the ZIB’s impressive electrochemical performance, the fabricated device shows good potential applications in portable and wearable electronics.