High capacity and temperature adaptive aqueous zinc ion batteries through Ca²⁺ intercalated into NH₄V₄O₁₀ cathode materials

Ammonium vanadate has been extensively studied as a promising electrode material for energy-storage devices with the tunable layered structure. Nevertheless, the excessive extraction of NH₄⁺ leads to the irreversible structure degradation and capacity decrease in cycling process. In this work, we introduce Ca²⁺ into the NH₄V₄O₁₀ samples via a simple hydrothermal route, which stabilizes the interlayer structures. At a current density of 0.2 A·g⁻¹, the assembled cells possess a discharge specific capacity of 547.9 mAh·g⁻¹. In addition, they still operate steadily at diverse temperatures from 20 to –20 °C. The soft-packaged devices also present remarkable mechanical properties under various folding degrees.