A Practical High-Energy Alkaline Aqueous Battery and Strategies to Suppress Its Hydrogen Evolution

High Resolution Image Download MS PowerPoint Slide Aqueous VB 2 –air batteries with high mass and volume specific energy and high safety have attracted an increasing amount of attention due to the multielectron reactions of VB 2 . However, the existing VB 2 -based batteries have many shortcomings, such as alkaline electrolyte volatilization and carbonation due to the half-open structure of air cathode and hydrogen evolution corrosion of the VB 2 anode. Thus, it is crucial to identify a cathode material with a stable structure, high energy density, and suitability for VB 2 -based batteries. In this work, four crystallographic structures of MnO 2 (α-, β-, γ-, and δ-) were selected as the cathode to construct a closed VB 2 -based alkaline battery. The results of galvanostatic discharge tests show that the γ-MnO 2 cathode has the highest discharge specific capacity of 280 mAh g –1 with utilization reaching 90.9%. XRD and in situ Raman analyses indicate that the cathode mainly undergoes a proton-embedded transition-type reaction. Additionally, V 2 O 5 was adopted as an anode additive to suppress hydrogen evolution corrosion. The closed VB 2 –MnO 2 aqueous battery with a designed capacity of 30–35 mAh cm –2 can achieve a discharge specific capacity of 2385 mAh g –1 at a current density of 800 mA g –1, which is 1080 mAh g –1 higher than that without additives, indicating that such an optimized VB 2 –MnO 2 aqueous battery has high practical potential.