Structural optimization of VO₂/NH₄V₄O₁₀ cathode materials for high-performance wide-temperature zinc-ion batteries

Abstract

Ammonium vanadate is considered as one of the most desirable cathodes for aqueous zinc ion batteries due to its favorable theoretical capacity and open crystal structure. Nevertheless, their further development is still limited by the poor structural stability, low electrical conductivity and compatibility of the electrolytes. In this work, we propose a regulation strategy through the pre-introduction of Ce ions. The incorporation of Ce ions increases the interlayer spacing of the host material, which improves the electrical conductivity and accelerates the ion transfer efficiency. The assembled Zn//0.05Ce-VO/NHVO cells deliver an initial capacity of 547.8 mAh g-1 at 0.2 A g-1. And they still keep a capacity of 331 mAh g-1 at 5 A g-1 after 4000 times cycling. Moreover, the system operates well over a wide temperature range (-20-40 oC). It keeps 92% and 87% capacity retention rate after 1500 cycles at the temperatures of -20 oC and 0 oC, respectively.