Luo Haiyan, Ji Xiangyu, Zhang Baodan, Chen Ming, Wu Xiaohong, Zhu Yuanlong, Yu Xiaoyu, Wang Junhao, Zhang Haitang, Hong Yuhao, Zou Yeguo, Feng Guang, Qiao Yu, Zhou Haoshen, Sun Shi-Gang
State Key Laboratory of Physical Chemistry of Solid Surfaces, Collaborative Innovation Center of Chemistry for Energy Materials (iChEM), Department of Chemistry, College of Chemistry and Chemical Engineering, Xiamen University, Xiamen, 361005, P. R. China.
State Key Laboratory of Coal Combustion, School of Energy and Power Engineering, Huazhong University of Science and Technology (HUST), Wuhan, 430074, P. R. China.
Angew Chem Int Ed Engl. 2024 Dec 16;63(51):e202412214. doi: 10.1002/anie.202412214.
Electrolyte engineering is crucial for improving cathode electrolyte interphase (CEI) to enhance the performance of lithium-ion batteries, especially at high charging cut-off voltages. However, typical electrolyte modification strategies always focus on the solvation structure in the bulk region, but consistently neglect the dynamic evolution of electrolyte solvation configuration at the cathode-electrolyte interface, which directly influences the CEI construction. Herein, we reveal an anti-synergy effect between Li-solvation and interfacial electric field by visualizing the dynamic evolution of electrolyte solvation configuration at the cathode-electrolyte interface, which determines the concentration of interfacial solvated-Li. The Li solvation in the charging process facilitates the construction of a concentrated (Li-solvent/anion-rich) interface and anion-derived CEI, while the repulsive force derived from interfacial electric field induces the formation of a diluted (solvent-rich) interface and solvent-derived CEI. Modifying the electrochemical protocols and electrolyte formulation, we regulate the "inflection voltage" arising from the anti-synergy effect and prolong the lifetime of the concentrated interface, which further improves the functionality of CEI architecture.
电解质工程对于改善阴极电解质界面（CEI）以提高锂离子电池的性能至关重要，尤其是在高充电截止电压下。然而，典型的电解质改性策略总是侧重于本体区域的溶剂化结构，却始终忽视了阴极 - 电解质界面处电解质溶剂化构型的动态演变，而这直接影响CEI的形成。在此，我们通过可视化阴极 - 电解质界面处电解质溶剂化构型的动态演变，揭示了锂溶剂化与界面电场之间的反协同效应，该效应决定了界面溶剂化锂的浓度。充电过程中的锂溶剂化有助于构建浓缩（富锂 - 溶剂/阴离子）界面和阴离子衍生的CEI，而界面电场产生的排斥力则诱导形成稀释（富溶剂）界面和溶剂衍生的CEI。通过修改电化学协议和电解质配方，我们调节了由反协同效应产生的“拐点电压”，并延长了浓缩界面的寿命，这进一步改善了CEI结构的功能。
