大湾区大学赵康宁团队近日研究了金属钙在Ca(TFSI)₂/DMAc电解质及其溶液中经合金界面和竞争性溶剂化的腐蚀。该成果于2025年6月18日发表在《德国应用化学》杂志上。

钙金属电池因其高理论容量和丰富的钙而成为大规模储能的有前景的候选者，但存在与钙金属不相容的电解质问题。研究组揭示了钙金属在Ca（TFSI）₂/DMAc电解质中的两种腐蚀类型：老化过程中溶剂还原引起的自然钝化和阴离子分解引起的电化学腐蚀。天然钝化层在钙金属表面显示出裂纹，钝化层通过TSFI-分解为大晶粒Ca²⁺绝缘体CaF₂加剧了电化学腐蚀，导致钙金属电池故障。 

研究组引入了双功能SnI₂电解质添加剂，以同时减轻这两种腐蚀。Sn²⁺阳离子促进自发电偶置换反应形成Ca-Sn合金，抑制自然钝化，而I-阴离子取代TSFI-参与Ca²⁺初级溶剂化壳，防止电化学TSFI-分解。通过利用上述特征，他们实现了500多个小时的稳定循环，在0.1 mA cm^-2和0.1 mAh cm^-2下的过电势降低到0.33 V，优于最先进的Ca（TFSI）₂基电解质。该工作提供了对钙金属表面腐蚀的基本理解，并将指导金属电池防腐的合适电解质设计。

附：英文原文

Title: Corrosion of Calcium Metal in Ca(TFSI)2/DMAc Electrolyte and its Solution  via  Alloy Interface and Competitive Solvation

Author: Jiang Liang, Min Wang, Shaohua Zhu, Dongyao Zhu, Rui Wang, Jiajing Wang, Lianmeng Cui, Meng Huang, Wenwei Zhang, Qinyou An, Lei Zhang, Kangning Zhao

Issue&Volume: 2025-06-18

Abstract: Calcium metal batteries are promising candidates for large-scale energy storage due to their high theoretical capacity and the abundance of calcium, but suffer from the incompatible electrolyte with calcium metal. Here, we unveil two types of corrosion of calcium metal in Ca(TFSI)2/DMAc electrolytes: native passivation from solvent reduction during aging and electrochemical corrosion from anion decomposition. The native passivation layer shows cracks in the calcium metal surface and the passivation layer aggravates the electrochemical corrosion by the decomposition of TSFI to the large grain Ca2+-insulator CaF2, leading to the calcium metal battery failure. We introduce bifunctional SnI2 electrolyte additive to simultaneously mitigate both corrosions. The Sn2+ cations facilitate the spontaneous galvanic replacement reaction to form the Ca-Sn alloy, inhibiting native passivation, while the I anions replace TSFI to participate in the Ca2+ primary solvation shell and prevent the electrochemical TSFI decomposition. By taking advantage of those features above, over 500 hours of stable cycling with a reduced overpotential of 0.33 V at 0.1 mA cm2 and 0.1 mAh cm2 were achieved, outperforming state-of-the-art Ca(TFSI)2-based electrolytes. Our work provides a fundamental understanding of corrosion at calcium metal surface and will guide suitable electrolyte design for anti-corrosion in metal batteries.

DOI: 10.1002/anie.202502729

Source: https://onlinelibrary.wiley.com/doi/10.1002/anie.202502729