Journal of Power Sources ( IF 8.1 ) Pub Date : 2023-06-08 , DOI: 10.1016/j.jpowsour.2023.233293
Shuangshuang Cui , Dan Zhang , Yang Gan
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Rechargeable aqueous Zn/MnO2 batteries receive extensive attention owing to the high capacity and safety. Pre-adding Mn2+ in electrolyte is widely adopted as an effective strategy to improve the electrochemical performance of Zn/MnO2 batteries. However, the reaction mechanism of MnO2 electrode during long cycles is still unclear with Mn2+ pre-added in electrolyte because of the complex reactions involved Mn2+. In this work, the reaction process of δ-MnO2 electrode with different concentration of Mn2+ pre-added in electrolyte is elucidated. The pre-addition of 0.1 M Mn2+ promotes the formation of vernadite on δ-MnO2 electrode and delivers extra capacity. Nevertheless, with the increasing Mn2+ concentration in electrolyte, electrochemical inactive ZnMn2O4 forms and the coverage of ZnMn2O4 nanoparticles on δ-MnO2 electrode hinders the electrodissolution of δ-MnO2 thus leading to the severe capacity fading. The different electrodeposition reactions with different concentration of Mn2+ pre-added in electrolyte cause the distinct irreversible transformation of δ-MnO2 into vernadite or ZnMn2O4 after long cycles. These findings shed new light on the reaction mechanism for δ-MnO2 electrode in aqueous zinc ion batteries.
中文翻译:
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Mn2+ 添加剂对水性 Zn/δ-MnO2 电池容量的影响:阐明 δ-MnO2 不可逆转变对 Mn2+ 浓度的依赖性
可充电水系Zn/MnO 2电池由于其高容量和安全性而受到广泛关注。在电解液中预添加Mn 2+作为提高Zn/MnO 2电池电化学性能的有效策略被广泛采用。然而,由于涉及Mn 2+的复杂反应,在电解质中预添加Mn 2+时,MnO 2电极在长循环过程中的反应机理仍不清楚。在这项工作中,阐明了在电解质中预添加不同浓度的Mn 2+的δ-MnO 2电极的反应过程。预加0.1 M Mn 2+促进了δ-MnO 2电极上蛭石的形成并提供了额外的容量。然而,随着电解质中Mn 2+浓度的增加,电化学惰性的ZnMn 2 O 4形成,ZnMn 2 O 4纳米粒子覆盖在δ-MnO 2电极上阻碍了δ-MnO 2的电溶解,从而导致严重的容量衰减。电解液中预加不同浓度Mn 2+的不同电沉积反应导致δ-MnO 2明显不可逆地转变为蛭石或ZnMn 2 O 4经过长时间的循环。这些发现为 δ-MnO 2电极在水性锌离子电池中的反应机制提供了新的思路。