Huang Jiangfeng, Xue Liang, Huang Yin, Jiang Yanchen, Wu Ping, Fan Xiulin, Zhu Junwu
Key Laboratory for Soft Chemistry and Functional Materials, Ministry of Education, School of Chemistry and Chemical Engineering, Nanjing University of Science and Technology, Nanjing, China.
Jiangsu Key Laboratory of New Power Batteries, School of Chemistry and Materials Science, Nanjing Normal University, Nanjing, China.
Nat Commun. 2024 Aug 6;15(1):6666. doi: 10.1038/s41467-024-51060-y.
LiMnO (LMO) is an attractive positive electrode material for aqueous lithium-ion batteries (ALIBs), but its inferior cycle performance limits the practical application. The degradation mechanism of LMO in ALIBs is still unclear, resulting in inability to predictably improve its structural stability. The electrode/electrolyte interface is believed to play an important role in electrode degradation. However, the interactions of the water-containing electrode/electrolyte interface of LMO are underexplored. In this work, we demonstrate the insertion of HO into LMO during cycling in aqueous electrolyte and elucidate the paradoxical effects of HO. The crystal HO enhances the structural stability of LMO by forming a gradient Mn-rich protective shell, but an excess amount of crystal HO leads to poor Li conductivity, resulting in rapid capacity fading. Combining electrochemical analyses, structural characterizations, and first-principles calculations, we reveal the intercalation of HO into LMO and its associated mechanism on the structural evolution of LMO. Furthermore, we regulate the crystal HO content in LMO by modifying the hydrogen bond networks of aqueous electrolyte to restrict HO molecule activity. This approach utilizes an appropriate amount of crystal HO to enhance the structural stability of LMO while maintaining sufficient Li diffusion.
LiMnO（LMO）是水系锂离子电池（ALIBs）中一种有吸引力的正极材料，但其较差的循环性能限制了实际应用。LMO在ALIBs中的降解机制仍不清楚，导致无法可预测地提高其结构稳定性。电极/电解质界面被认为在电极降解中起重要作用。然而，LMO含水电极/电解质界面的相互作用尚未得到充分研究。在这项工作中，我们证明了在水系电解质循环过程中HO插入LMO，并阐明了HO的矛盾效应。晶体HO通过形成富含Mn的梯度保护壳增强了LMO的结构稳定性，但过量的晶体HO导致Li传导性差，从而导致容量快速衰减。结合电化学分析、结构表征和第一性原理计算，我们揭示了HO插入LMO及其对LMO结构演变的相关机制。此外，我们通过修饰水系电解质的氢键网络来调节LMO中的晶体HO含量，以限制HO分子的活性。这种方法利用适量的晶体HO来增强LMO的结构稳定性，同时保持足够的Li扩散。
