Tetrahydrofuran intercalated layered vanadium(III) phosphate electrode for aqueous zinc-ion battery

Layered VOPO4·2H2O is considered a good electrode material structure for the insertion and extraction of energy storage ions, but the lattice water may affect the electrochemical stability. To provide more active site and more stable layered structure, the lattice water was replaced by tetrahydrofuran (THF), and the THF intercalated VOPO4 was obtained. The interlayer spacing has changed from 7.4 to 6.3 Å after THF intercalation, and the layered structure of VOPO4-THF is well preserved. It offers enhanced structural stability during charge and discharge processes, minimizing electrode degradation. In addition, increasing the oxidation state of pentavalent vanadium in VOPO4-THF is also beneficial for enhancing the capacitance of electrode materials. Combining the stable layered structure with a high oxidation state, VOPO4-THF electrode material exhibits good capacity and long cycle life. Our work convert traditional VOPO4·2H2O electrode into a promising high-performance active electrode for zinc-ion batteries.