Controlling Dissolution-Redeposition via Solvating Power Engineering for Stable Organic Batteries

Abstract

Organic electrode materials (OEMs) have emerged as promising alternatives to transition-metal-based electrodes owing to their sustainability, molecular tunability, and environmental compatibility. However, their practical implementation is still challenged because of the dissolution problems during cycling. Recent studies have suggested that strong ion–solvent interactions facilitate co-intercalation of solvated complexes into layered organic lattices such as Perylene-3,4,9,10-tetracarboxylic dianhydride (PTCDA), thereby triggering lattice distortion and accelerated dissolution. This insight established co- intercalation suppression as the prevailing design rule for enhancing electrode stability. This finding underscored that controlling ion–solvent interactions and desolvation energy is essential for suppressing co-intercalation and improving electrode stability, establishing the prevailing design rule that complete prevention of co-intercalation is key to stabilizing organic electrodes. Nevertheless, this framework may be overly restrictive. The occurrence of co-intercalation alone does not necessarily dictate degradation; rather, electrode stability depends on how the electrode accommodates this process within the surrounding electrolyte environment. In particular, the solvating power of solvents governs the reversibility of subsequent dissolution–redeposition dynamics, determining whether co-intercalation leads to irreversible material loss or can proceed in a controlled and reversible manner. In this study, we systematically tuned the molecular structure of ether solvents to control their solvating power and examined its effect on the lithiation behavior of PTCDA electrodes. Strong solvating power solvents such as 1,2-dimethoxyethane (DME) induced high solubility of reduced species, leading to excessive dissolution and irreversible structural collapse. Weakly solvating power solvents such as methoxycyclopentane (CPME) suppressed co-intercalation but resulted in non-uniform precipitation and localized degradation of the cathode, accompanied by parasitic redeposition on the lithium-metal surface. In contrast, the intermediate-solvating-power solvent diethylene glycol dimethyl ether (DEGDME) provided balanced solubility, enabling uniform and reversible dissolution–redeposition while maintaining lattice integrity even under co-intercalation conditions. Consequently, DEGDME based cells achieved the most stable long-term performance, retaining approximately 80% of their initial capacity over 240 cycles with consistent Coulombic efficiency.