Membrane‐Free Zn/MnO<sub>2</sub> Flow Battery for Large‐Scale Energy Storage
Guodong Li, Wei Chen, Hao Zhang, Yongji Gong, Feifei Shi, Jiangyan Wang, Rufan Zhang, Guangxu Chen, Yang Jin, Tong Wu, Zhiyong Tang, Yi Cui
Abstract
Abstract The traditional Zn/MnO 2 battery has attracted great interest due to its low cost, high safety, high output voltage, and environmental friendliness. However, it remains a big challenge to achieve long‐term stability, mainly owing to the poor reversibility of the cathode reaction. Different from previous studies where the cathode redox reaction of MnO 2 /MnOOH is in solid state with limited reversibility, here a new aqueous rechargeable Zn/MnO 2 flow battery is constructed with dissolution–precipitation reactions in both cathodes (Mn 2+ /MnO 2 ) and anodes (Zn 2+ /Zn), which allow mixing of anolyte and catholyte into only one electrolyte and remove the requirement for an ion selective membrane for cost reduction. Impressively, this new battery exhibits a high discharge voltage of ≈1.78 V, good rate capability (10C discharge), and excellent cycling stability (1000 cycles without decay) at the areal capacity ranging from 0.5 to 2 mAh cm ‐2 . More importantly, this battery can be readily enlarged to a bench scale flow cell of 1.2 Ah with good capacity retention of 89.7% at the 500th cycle, displaying great potential for large‐scale energy storage.