Control of electrolyte desolvation energy suppressing co-intercalation mechanism and organic electrode dissolution

Abstract

Despite numerous studies aimed at solving the detrimental dissolution issue of organic electrode materials (OEMs), a fundamental understanding of their dissolution mechanism has not yet been established. Herein, we systematically investigate how changes in electrolyte composition affect the ion-solvent interactions propagating to OEM dissolution by changing the cation. The cyclability of OEM is significantly different by alkali cations, where the OEM with K is stable even after 300 cycles and that with Li is drastically decayed within 100 cycles. This different behavior is owing to the dissolution of OEM into electrolytes, and the dissolution of OEMs was found to be highly dependent on the cation-solvent interaction. Strong cation-solvent interactions induce cointercalation into the layered structure of the electrode and cause electrode deformation. This behavior allows OEMs to easily detach from their original location, consequently leading to dissolution and severe capacity decay. The cation-solvent interaction-dependent phenomenon is similar to that of OEMs with high-concentration electrolytes, in which fewer cation-solvent pairs exist. The result provides insight into proper electrolyte selection and is expected to set a constructive milestone in the utilization of organic electrodes.