中南大学材料科学与工程学院周江团队近日取得一项新成果。经过不懈努力，他们提出了电化学-化学过程调控实现Zn-MnO₂电解电池中Mn²⁺/MnO₂高可逆转化反应。相关论文于2025年2月18日发表在《德国应用化学》杂志上。

本文基于双向电化学-化学模型，提出了一种以FeSO₄为介质的新型水性SiO₂胶体电解质（简称SF电解质），以实现对MnO₂沉积/溶解过程的双重调控。在充电过程中，位于碳毡界面和电解质体相处的SiO₂胶体粒子同时为不同取向的Mn³⁺提供了充足的歧化位点，引导MnO₂有序快速沉积。同时，在放电过程中引入Fe²⁺介质，可以与电解液中SiO₂颗粒上的MnO₂充分反应，从而进一步实现Mn²⁺/MnO₂的高效转化。结果表明，在10 mA h cm^-2下，电解锌- MnO₂电池可以稳定运行550次，并在20 mA h cm^-2的高区域容量下具有优异的可逆性。这项工作证明了胶体电解质在调节电化学-化学过程中稳定电解Zn-MnO₂电池的可行性。

据了解，尽管人们对具有优异输出电压和高理论容量的电解Zn-MnO₂电池有着广泛的兴趣，但游离Mn³⁺的自发歧化反应以及无序沉积的非活性MnO₂导致了Mn²⁺/MnO₂转换可逆性低，严重影响了其循环稳定性。

附：英文原文

Title: Achieving Highly Reversible Mn²⁺/MnO₂ Conversion Reaction in Electrolytic Zn-MnO₂ Batteries via Electrochemical-Chemical Process Regulation

Author: Hengyue Chen, Pengchao Ruan, Hao Zhang, Zeinhom M. El-Bahy, Mohamed M. Ibrahim, Bingan Lu, Jiang Zhou

Issue&Volume: 2025-02-18

Abstract: Despite the widespread interest in electrolytic Zn-MnO₂ batteries with excellent output voltage and high theoretical capacity, the spontaneous disproportionation reaction of free Mn³⁺ along with the disorderly deposited inactive MnO₂ results in the low Mn²⁺/MnO₂ conversion reversibility, which seriously affects their cycling stability. Here, we propose a novel aqueous SiO₂ colloidal electrolyte with FeSO₄ mediator (denoted as SF electrolyte) based on a bidirectional electrochemical-chemical model to achieve dual regulation of the MnO₂ deposition/dissolution process. During the charging process, the SiO₂ colloidal particles located at the carbon felt interface and the electrolyte bulk phase simultaneously provide sufficient disproportionation sites for the diffused Mn³⁺ to guide the orderly rapid deposition of MnO₂. Meanwhile, the introduction of Fe²⁺ mediators during the discharge process can sufficiently react with MnO₂ on the SiO₂ particles in the electrolyte, thereby further enabling the efficient conversion of Mn²⁺/MnO₂. Consequently, electrolytic Zn-MnO₂ battery with SF electrolyte can stably run for 550 cycles at 10 mA h cm^-2 and achieve superior reversibility at a high area capacity of 20 mA h cm^-2. This work demonstrates the feasibility of colloidal electrolytes in modulating electrochemical-chemical processes to stabilize electrolytic Zn-MnO₂ batteries.

DOI: 10.1002/anie.202423999

Source: https://onlinelibrary.wiley.com/doi/10.1002/anie.202423999