Entropy Engineering toward Positive Temperature Coefficient and Large Voltage in High-Temperature Zinc-Ion Batteries

Voltage attenuation at high temperatures poses a significant challenge to the commercial application of aqueous zinc-ion batteries (AZIBs). Herein, we first reversed the temperature coefficient of voltage in AZIB, enhancing its high-temperature performance. The introduction of the low-cost ligand 3,5-diamino-1,2,4-triazole (daTZ) into the electrolyte results in stable Zn2(daTZ)3(SO4)2 with a triligand-bridged dimer structure. This modification led to a significant negative entropy change (ΔS) in the anode reaction during discharge, increasing the temperature coefficient of full battery from −0.394 mV·K–1 to recorded 2.088 mV·K–1 and improving the operating voltage at 60 °C by 156 mV. Additionally, daTZ disrupted the solvation structure between Zn2+ and H2O, reducing side reactions and achieving stable cycling for up to 195 cycles with only a 25% capacity attenuation. This work offers a strategy to regulate the temperature coefficient and optimize the high-temperature voltage of batteries through entropy regulation in electrolytes.