中国科学技术大学余彦团队报道了Sn(OTf)₂添加剂定制Na⁺溶液化环境和电极-电解质界面，在不燃磷酸盐电解质中的相互作用，实现安全高效的Na-S电池。相关研究成果发表在2024年1月29日出版的《德国应用化学》。

室温钠硫（RT-Na–S）电池有望用于低成本和大规模的储能应用。然而，由于传统电解质的高度易燃性，这些电池受到安全问题的困扰。尽管不可燃电解质消除了火灾风险，但由于与钠金属阳极和硫阴极的兼容性较差，它们往往会导致电池性能受损。

该文中，研究人员开发了一种三氟甲磺酸锡(Sn(OTf)₂) 在不可燃磷酸盐电解质中的添加剂，通过调节Na⁺溶剂化环境和界面化学来提高RT-Na–S电池的循环稳定性。添加剂降低了Na⁺的脱溶能，提高了电解质的稳定性。此外，它还促进了Na–Sn合金基阳极固体电解质界面（SEI）和阴极电解质界面（CEI）的构建。这些界面有助于抑制钠枝晶的生长和多硫化钠（NaPS）的溶解/穿梭，从而提高可逆容量。具体而言，采用设计电解质的Na–S电池在0.5 A g^-1的条件下将容量从322mAhg^-1提高到906mAhg^-1。

该项研究为开发RT Na–S电池中安全高性能的电解质提供了宝贵的见解。

附：英文原文

Title: Tailoring Na+ Solvation Environment and Electrode–Electrolyte Interphases with Sn(OTf)2 Additive in Non-flammable Phosphate Electrolytes towards Safe and Efficient Na–S Batteries

Author: Lifeng Wang, Naiqing Ren, Wei Jiang, Hai Yang, Shufen Ye, Yang Jiang, Ghulam Ali, Li Song, Xiaojun Wu, Xianhong Rui, Yu Yao, Yan Yu

Issue&Volume: 2024-01-29

Abstract: Room-temperature sodium–sulfur (RT Na–S) batteries are promising for low-cost and large-scale energy storage applications. However, these batteries are plagued by safety concerns due to the highly flammable nature of conventional electrolytes. Although nonflammable electrolytes eliminate the risk of fire, they often result in compromised battery performance due to poor compatibility with sodium metal anode and sulfur cathode. Herein, we develop an additive of tin trifluoromethanesulfonate (Sn(OTf)2) in non-flammable phosphate electrolytes to improve the cycling stability of RT Na–S batteries via modulating the Na+ solvation environment and interface chemistry. The additive reduces the Na+ desolvation energy and enhances the electrolyte stability. Moreover, it facilitates the construction of Na–Sn alloy-based anode solid electrolyte interphase (SEI) and cathode electrolyte interphase (CEI). These interphases help to suppress the growth of Na dendrites and the dissolution/shuttling of sodium polysulfides (NaPSs), resulting in improved reversible capacity. Specifically, the Na–S battery with the designed electrolyte boosts the capacity from 322 to 906 mAh g-1 at 0.5 A g-1. This study provides valuable insights for the development of safe and high-performance electrolytes in RT Na–S batteries.

DOI: 10.1002/anie.202320060

Source: https://onlinelibrary.wiley.com/doi/10.1002/anie.202320060