Regulating interfacial structure enables high-voltage dilute ether electrolytes
Huwei Wang, Jinkai Zhang, Haodong Zhang, Wei Li, Ming Chen, Qing Guo, Kah Chun Lau, Liang Zeng, Guang Feng, Dengyun Zhai, Feiyu Kang
Abstract
Poor oxidation stability of ether solvents at the cathode restricts the use of dilute ether electrolytes with conventional concentrations around 1 M in high-voltage, lithium-metal batteries. Here, we report an anion-adsorption approach to altering the ether solvent environment within the electrical double layer (EDL) at the cathode by adding a small amount of nitrate so that the oxidation tolerance of nitrate-containing dilute ether electrolytes is enhanced up to 4.4 V (versus Li/Li+), leading to complete compatibility with high-voltage cathodes and exhibiting superior cycling stability. Constant potential molecular dynamics simulations reveal that ether molecules are mostly excluded from the cathode because of nitrate occupation in the inner layer of the EDL, thus suppressing ether oxidative decomposition. This work highlights that regulating the interfacial structure by adding surface adsorbates, rather than passivating the cathode-electrolyte interphase or changing ion solvation, can help to enhance the oxidation stability of ether solvents.