Wei Aijia, Yang Yuqi, Mu Jinping, He Rui, Li Xiaohui, Zhang Haipeng, Liu Zhenfa, Wang Shasha, Zheng Yong, Mei Shuxing
Institute of Energy Resources, Hebei Academy of Sciences, Shijiazhuang, 050081, Hebei Province, People's Republic of China.
State Key Laboratory of Heavy Oil Processing at Karamay, China University of Petroleum-Beijing at Karamay, Karamay, 834000, China.
Sci Rep. 2025 Feb 20;15(1):6186. doi: 10.1038/s41598-025-90702-z.
The instability of the electrode/electrolyte interface and the metal-ions dissolution of high-voltage LiNiMnO (LNMO) material lead to significant degradation of cycling performance, thereby limiting the large-scale application of LNMO-based batteries. Here, inorganic Mg/Ca/Sr-contained phosphates (MgHPO, CaHPO, and SrHPO) are used individually as functional additives of standard electrolytes to enhance the cycling performance of LNMO. Combined with theoretical calculations, a series of electrochemical measurements and characteristics corroborate that the MgHPO is the optimal additive and can preferentially undergo oxidation and reduction decomposition over carbonate solvents. Electrochemical results reveal that the LNMO/Li half-cell containing the MgHPO additive shows a capacity retention of 91.9% after 500 cycles at 5 C, higher than that obtained with STD (76.5%). In addition, the LNMO/graphite (Gr) full-cell with MgHPO additive increases the capacity retention from 70.8 to 78.0% after 100 cycles at 0.5 C. The addition of MgHPO allows a thin, uniform, and conductive cathode-electrolyte interphase (CEI) and solid-electrolyte interphase (SEI) film to be formed on the LNMO cathode and graphite anodes. Furthermore, the preferential reduction of MgHPO inhibits the lithium dendritic growth and enables the formation of a more stable SEI on the Li anode. Besides, the MgHPO additive serves as a scavenger of detrimental HF, thus suppressing the Ni/Mn ions dissolution and improving the structural stability of LNMO. This study provides a cost-effective strategy involving the use of an inorganic additive for improving the electrochemical performance of high-voltage lithium-ion batteries.
电极/电解质界面的不稳定性以及高压LiNiMnO（LNMO）材料中金属离子的溶解导致循环性能显著下降，从而限制了基于LNMO的电池的大规模应用。在此，含无机Mg/Ca/Sr的磷酸盐（MgHPO、CaHPO和SrHPO）分别用作标准电解质的功能添加剂，以提高LNMO的循环性能。结合理论计算，一系列电化学测量和特性证实MgHPO是最佳添加剂，并且相较于碳酸酯溶剂，它能优先发生氧化和还原分解。电化学结果表明，含有MgHPO添加剂的LNMO/Li半电池在5C下循环500次后容量保持率为91.9%，高于使用STD时获得的容量保持率（76.5%）。此外，含有MgHPO添加剂的LNMO/石墨（Gr）全电池在0.5C下循环100次后，容量保持率从70.8%提高到了78.0%。添加MgHPO可使在LNMO阴极和石墨阳极上形成薄的、均匀的且导电的阴极-电解质界面（CEI）和固体电解质界面（SEI）膜。此外，MgHPO的优先还原抑制了锂枝晶生长，并使得在锂阳极上形成更稳定的SEI。此外，MgHPO添加剂可作为有害HF的清除剂，从而抑制Ni/Mn离子溶解并提高LNMO的结构稳定性。本研究提供了一种具有成本效益的策略，即使用无机添加剂来改善高压锂离子电池的电化学性能。
