New Dissolution Chemistry of Nylon Promises Reversible Li-Metal Batteries

Integrating additives into electrolytes serves as an effective strategy for cultivating robust interphases in batteries. Traditionally, the emphasis has been placed on small-molecule additives, whereas macromolecules have been largely overlooked due to their insolubility in conventional solvents. In this study, we establish that the macromolecule polyamide (nylon, PA) can be effectively solubilized in Li⁺ electrolytes and utilized as a macromolecular additive. The dissolution capability of the electrolyte is governed by multiple parameters. Specifically, the dissolution of PA is facilitated by stronger Lewis acidity of the cations, weaker solvating capabilities of the solvents, smaller anions, and higher salt concentrations. At the molecular level, coordination of cations with carbonyl groups and the formation of H-bonds between anions and amido groups disrupt the crystalline structure of PA, thereby enhancing its solubility. As a paradigm for practicability, the solubilized PA in carbonate-based electrolytes induces Li₃N-rich interphases, significantly boosting the rechargeability of Li-metal batteries (LMBs).