Spent shell as a calcium source for constructing calcium vanadate for high-performance Zn-ion batteries

In this article, waste shell is directly used as a raw material to synthesize CaV₃O₇ as a cathode for aqueous zinc ion batteries. The obtained cathode material exhibits better performance than that of CaV₃O₇ prepared from pure calcium carbonate as a raw material. At 0.1 A g^-1, the CaV₃O₇ prepared by spent shell as a calcium source displays a highly reversible discharge capacity of 373 mA h g^-1. A high initial discharge capacity of 177.7 mA h g^-1 can be gained at 5.0 A g^-1, and the specific capacity remains at 133.3 mA h g^-1 with a capacity retention of 75% after 3000 cycles. This work may spark inspiration for energy storage and generate more effective routes for recycling solid waste.