Metal-Free Eutectic Electrolyte with Weak Hydrogen Bonds for High-Rate and Ultra-Stable Ammonium-Ion Batteries.
Hu HongJiaxiong ZhuYiqiao WangZhiquan WeiXun GuoShuo YangRong ZhangHuilin CuiQing LiDechao ZhangChunyi ZhiPublished in: Advanced materials (Deerfield Beach, Fla.) (2023)
As the need for sustainable battery chemistry grows, non-metallic ammonium ion (NH 4 + ) batteries are receiving considerable attention because of their unique properties, such as low cost, nontoxicity, and environmental sustainability. In this study, we elucidated the solvation interactions between NH 4 + and solvents and proposed design principles for NH 4 + weakly solvated electrolytes. Given that hydrogen bond interactions dominate the solvation of NH 4 + and solvents, the strength of the solvent's electrostatic potential directly determines the strength of its solvating power. As a proof of concept, succinonitrile with relatively weak electronegativity was selected to construct a metal-free eutectic electrolyte (MEE). As expected, this MEE was able to significantly broaden the electrochemical stability window and reduce the solvent coordination number and binding energy in the solvation shell, which led to a lower desolvation energy barrier and a fast charge transfer process. As a result, the as-constructed NH 4 -ion batteries exhibited superior reversible rate capability (energy density of 65 Wh kg -1 total active mass at 600 W kg -1 ) and unprecedented long-term cycling performance (retention of 90.2% after 1000 cycles at 1.0 A g -1 ). Our proposed methodology for constructing weakly hydrogen bonded electrolytes will provide guidelines for implementing high-rate and ultra-stable NH 4 + -based energy storage systems. This article is protected by copyright. All rights reserved.