Zhao Xuesong, Zhang Xuan, Dong Ning, Yan Mengdie, Zhang Fenglin, Mochizuki Kenji, Pan Huilin
Department of Chemistry, Zhejiang University, Hangzhou, 310027, China.
Small. 2022 May;18(21):e2200742. doi: 10.1002/smll.202200742. Epub 2022 Apr 22.
Mild aqueous Zn batteries have attracted increasing attention for energy storage due to the advantages of high safety and low cost; however, the rechargeability of Zn anodes is one major issue for practical applications. In this work, an effective approach is proposed to improve the reversibility and stability of Zn anodes using advanced acidic electrolytes. A trace amount of acetic acid (HAc) is employed as a buffering agent to provide a stable pH environment in aqueous Zn electrolytes, and thus suppress passivation from precipitation reactions on Zn electrodes. Meanwhile, tetramethylene sulfone (TMS) is introduced as the critical component to stabilize the Zn anodes in the acidic electrolyte. TMS greatly strengthens the hydrogen-bonding network with reduced H O activity and extends the electrochemical window of acidic electrolytes. With the optimal 3 m Zn(OTF) in (H O-HAc)/TMS acidic electrolyte (pH 1.6), the Zn electrode exhibits a coulombic efficiency of >99.8% and smooth Zn deposition. The Zn-V O full cell demonstrates ultra-stable cycling over 20 000 cycles with a low decay rate of 0.0009% for each cycle at a negative/postive capacity ratio of 6.5. This work provides an insightful perspective to stabilize Zn electrodes by regulating the pH environment and limiting the H O activity simultaneously for long-life Zn anodes.
温和水系锌电池因其高安全性和低成本的优势在能量存储领域受到越来越多的关注；然而，锌负极的可再充电性是实际应用中的一个主要问题。在这项工作中，提出了一种有效的方法，即使用先进的酸性电解质来提高锌负极的可逆性和稳定性。微量乙酸（HAc）用作缓冲剂，在水系锌电解质中提供稳定的pH环境，从而抑制锌电极上沉淀反应导致的钝化。同时，引入四亚甲基砜（TMS）作为关键成分，以在酸性电解质中稳定锌负极。TMS通过降低H₂O活性极大地增强了氢键网络，并扩展了酸性电解质的电化学窗口。在（H₂O-HAc）/TMS酸性电解质（pH 1.6）中使用最佳的3 m Zn（OTF）₂时，锌电极表现出大于99.8%的库仑效率和光滑的锌沉积。锌-二氧化钒全电池在负/正极容量比为6.5时，展示了超过20000次循环的超稳定循环，每次循环的低衰减率为0.0009%。这项工作为通过同时调节pH环境和限制H₂O活性来稳定锌电极以实现长寿命锌负极提供了深刻的见解。
