Recently, an undergraduate research team supervised by Professor Yi Tingfeng from the School of Resources and Materials at NEU Qinhuangdao has made significant progress in the field of cathode materials for aqueous zinc-ion batteries. Their research paper, titled "Reversible construction of rigid-flexible layered-tunnel heterostructures endowing MnO₂ cathodes with robust zinc ion storage," has been published in the Journal of Energy Chemistry—a leading journal under the Chinese Excellence Initiative for Science and Technology Journals and classified as a Tier 1 journey by the Chinese Academy of Sciences. The first author of the paper is Song Zhuoyun, a 2022 undergraduate student majoring in Materials Science and Engineering at NEU Qinhuangdao. The corresponding authors are Professor Yi Tingfeng and Dr. Liu Zonglin from NEU Qinhuangdao, and Professor Xie Ying from Heilongjiang University. NEU Qinhuangdao is listed as the primary affiliation.
Aqueous zinc ion batteries (AZIBs) have become a research hotspot in energy storage due to their low cost, high safety, and environmental friendliness. However, their commercialization faces a key challenge: the poor conductivity and structural instability of cathode materials, which lead to limited cycle life. In recent years, constructing heterostructures has been widely recognized as an effective strategy to improve the capacity and structural stability of manganese-based cathode materials. Previous studies have used composite materials to create heterogeneous interfaces and enhance electrochemical performance. However, such methods are often limited by interface instability caused by lattice mismatch between the two phases, limiting further progress.
To address this, the author team innovatively introduced Ce³⁺ and Cu²⁺ into layered δ-MnO₂, constructing a cathode material with a δ/α-MnO₂ heterostructure. Theoretical calculations and experiments demonstrate that Cu²⁺ substitution for Mn activates the Mn⁴⁺/Mn²⁺ redox pair, enabling localized two-electron transfer and significantly enhancing specific capacity. Ce³⁺ doping induces partial conversion of δ-MnO₂ to α-MnO₂, forming a heterostructure with a built-in electric field. This structure employs a "rigid-flexible" system composed of an α-phase rigid skeleton and a δ-phase flexible zinc storage layer, effectively suppressing interlayer collapse and volume expansion while preventing stress concentration. Ultimately, the CCMO cathode achieved a high capacity of 455.4 mAh g⁻¹ (at 0.2 A g⁻¹), excellent rate performance, and long-term cycling stability (95% capacity retention after 1,500 cycles at 2 A g⁻¹).
This study demonstrates that a synergistic strategy combining heterostructure engineering and valence state regulation can simultaneously enhance the capacity and stability of MnO₂ cathodes. It provides a novel design strategy for manganese-based cathodes in AZIBs, thereby advancing their practical application.
