Wu Mingzhu, Yang Mingchen, Yu Jiangtao, Ma Xinyu, Sun Shipeng, She Yupo, Yang Jinhua, Zou Xiuyang, Hu Yin, Yan Feng
Jiangsu Engineering Laboratory of Novel Functional Polymeric Materials, Jiangsu Key Laboratory of Advanced Negative Carbon Technologies College of Chemistry, Suzhou Key Laboratory of Soft Material and New Energy, College of Chemistry, Chemical Engineering and Materials Science, Soochow University, Suzhou 215123, China.
Jiangsu Engineering Research Center for Environmental Functional Materials, School of Chemistry and Chemical Engineering, Huaiyin Normal University, Huaian 223300, China.
J Am Chem Soc. 2024 Dec 25;146(51):35229-35241. doi: 10.1021/jacs.4c12353. Epub 2024 Dec 13.
Electrolytes for high-performance sodium metal batteries (SMBs) are expected to have high electrode compatibility, low solvation energy, and nonflammability. However, conventional flammable carbonate ester electrolytes show high Na desolvation energy and poor compatibility with sodium metal anodes, leading to slow Faradaic reactions and significant degradation of SMBs. Herein, we report a weakly solvating electrolytes (WSEs) design developed by an ionized ether-induced solvent molecule polarization strategy. The steric hindrance and electron-withdrawing effect of the pyrrolidine cation weaken the solvation ability of the ionized ether and enable carbonate ester with low solvation energy through intermolecular polarization interactions. It enables WSEs with fast Na migration kinetics and electric-field-reinforced cationic electrode/electrolyte interface, thereby promoting the stability and reversibility of SMBs even under high-charge-rate conditions. The Na||NaV(PO) battery with ionized ether-based WSEs exhibits a capacity retention of 83.5% with an average Coulombic efficiency (CE) of 99.69% after 500 cycles at 10C. Furthermore, the Na||NaFe(SO) cells maintained 92.8% capacity retention after 1000 cycles at 5C with an average CE of 99.77% at a cutoff voltage of 4.5 V. The ionized ether also eliminates the fire and safety risks associated with WSEs. This work offers valuable insights into the design of WSEs for safe and high-performance sodium metal batteries.
用于高性能钠金属电池（SMB）的电解质有望具有高电极兼容性、低溶剂化能和不可燃性。然而，传统的易燃碳酸酯电解质表现出高的钠去溶剂化能，并且与钠金属负极的兼容性较差，导致法拉第反应缓慢以及SMB显著降解。在此，我们报道了一种通过离子化醚诱导的溶剂分子极化策略开发的弱溶剂化电解质（WSE）设计。吡咯烷阳离子的空间位阻和吸电子效应削弱了离子化醚的溶剂化能力，并通过分子间极化相互作用使碳酸酯具有低溶剂化能。这使得WSE具有快速的钠迁移动力学和电场增强的阳离子电极/电解质界面，从而即使在高充电率条件下也能促进SMB的稳定性和可逆性。采用基于离子化醚的WSE的Na||NaV(PO)电池在10C下500次循环后容量保持率为83.5%，平均库仑效率（CE）为99.69%。此外，Na||NaFe(SO)电池在5C下1000次循环后容量保持率为92.8%，在4.5V的截止电压下平均CE为99.77%。离子化醚还消除了与WSE相关的火灾和安全风险。这项工作为安全和高性能钠金属电池的WSE设计提供了有价值的见解。
