Fe 3+ -driven tunnel engineering for stabilizing metastable ramsdellite MnO 2 in high-performance zinc-ion batteries

作者：Yutong Meng, Yangfan Li, Hang Xiao, Xiang Wang, Zhiwen Wang, Fan Zhang, Wenqing Ma, Da Xiong, Zisheng Xiao, Jiang Yin, Zhiye Yuan, Tong Zhou, Lishan Yang, Changhui Liu, Xiongwei Wu · 发表于：Energy Materials · 年份：2025 · DOI：10.20517/energymater.2025.113 · 被引用次数：10 · 研究领域：Advanced battery technologies research、Advancements in Battery Materials、Supercapacitor Materials and Fabrication

Ramsdellite MnO2 (R -MnO2), with its expanded (1 × 2) tunnels, offers superior Zn2+ diffusion kinetics for aqueous zinc-ion batteries but suffers from metastability-induced phase collapse. Herein, Fe3+ doping is demonstrated as a critical strategy to thermodynamically stabilize R -MnO2 while optimizing its electrochemical functionality. Through a synergistic H+/Fe3+ hydrothermal process, spent ZnMn2O4 from alkaline batteries is converted into orthorhombic R -FexMn1-xO2 nanocrystals. Fe3+ incorporation enlarges the tunnel structure, reduces surface energy, and mitigates Jahn-Teller distortion by increasing the Mn4+/Mn3+ ratio. This yields a high specific surface area, enhanced ion diffusion kinetics, and exceptional cycling stability. The R -FexMn1-xO2 cathode achieves a 286.8 mAh g-1 capacity at 0.1 A g-1, outperforming β -MnO2 (30.9 mAh g-1 at 1.5 A g-1). This work establishes Fe3+ doping as an essential mechanism for stabilizing high-performance metastable cathodes, enabling sustainable upcycling of battery waste.