武汉大学曹余良团队报道了通过阴离子-阳离子相互作用调制设计高安全和长寿命钠离子电池的先进电解质。相关研究成果发表在2024年6月4日出版的《美国化学会杂志》。

易燃电解质引起的安全隐患一直是钠离子电池实际应用的主要障碍。采用不可燃的全磷酸盐电解质可以有效提高SIBs的安全性，然而，传统的低浓度磷酸盐电解质与碳基阳极不兼容。

该文中，研究人员报道了一种阴离子-阳离子相互作用调节策略，以设计具有优异物理化学性质的低浓度磷酸盐电解质。引入三（2,2,2-三氟乙基）磷酸酯（TFEP）作为共溶剂，通过增强阴离子-阳离子相互作用来调节离子-溶剂配位（ISC）结构，形成稳定的阴离子诱导ISC（AI-ISC）结构，即使在低盐浓度（1.22M）下也是如此。

通过光谱分析和理论计算，揭示了这些电解质稳定的潜在机制。令人印象深刻的是，硬碳（HC）阳极和Na₄Fe_2.91(PO₄)₂(P₂O₇) (NFPP)阴极都能很好地与所开发的电解质一起工作。所设计的磷酸盐电解质使Ah水平的HC//NFPP袋状电池在2000次循环后具有超过99.9%的平均库仑效率（CE）和84.5%的容量保持率。此外，袋状电池可以在较宽的温度范围（20至60°C）内运行，并成功通过严格的安全测试。

该项工作为高安全性和长寿命SIBs的电化学相容性电解质的设计提供了新的见解。

附：英文原文

Title: Designing Advanced Electrolytes for High-Safety and Long-Lifetime Sodium-Ion Batteries via Anion–Cation Interaction Modulation

Author: Hui Chen, Kean Chen, Jingyu Yang, Biaolan Liu, Laibing Luo, Hui Li, Long Chen, Along Zhao, Xinmiao Liang, Jiwen Feng, Yongjin Fang, Yuliang Cao

Issue&Volume: June 4, 2024

Abstract: Safety hazards caused by flammable electrolytes have been major obstacles to the practical application of sodium-ion batteries (SIBs). The adoption of nonflammable all-phosphate electrolytes can effectively improve the safety of SIBs; however, traditional low-concentration phosphate electrolytes are not compatible with carbon-based anodes. Herein, we report an anion–cation interaction modulation strategy to design low-concentration phosphate electrolytes with superior physicochemical properties. Tris(2,2,2-trifluoroethyl) phosphate (TFEP) is introduced as a cosolvent to regulate the ion–solvent-coordinated (ISC) structure through enhancing the anion–cation interactions, forming the stable anion-induced ISC (AI-ISC) structure, even at a low salt concentration (1.22 M). Through spectroscopy analyses and theoretical calculations, we reveal the underlying mechanism responsible for the stabilization of these electrolytes. Impressively, both the hard carbon (HC) anode and Na4Fe2.91(PO4)2(P2O7) (NFPP) cathode work well with the developed electrolytes. The designed phosphate electrolyte enables Ah-level HC//NFPP pouch cells with an average Coulombic efficiency (CE) of over 99.9% and a capacity retention of 84.5% after 2000 cycles. In addition, the pouch cells can operate in a wide temperature range (20 to 60 °C) and successfully pass rigorous safety testing. This work provides new insight into the design of the electrochemically compatibility electrolyte for high-safety and long-lifetime SIBs.

DOI: 10.1021/jacs.4c01395

Source: https://pubs.acs.org/doi/abs/10.1021/jacs.4c01395