Cathode Electrolyte Interphase Regulation for High-Performance Lithium–Organic Batteries

Abstract

Organic cathode materials (OCMs) have garnered significant attention due to their high capacity and environmental friendliness. However, their practical application is severely limited by their strong interaction with conventional liquid electrolytes, leading to serious dissolution. To address this issue, we introduced a series of lithium fluorocarboxylates (LFCs) with a low conjugation effect and high energies of the highest occupied molecular orbital (HOMO) into the electrolyte, forming a favorable cathode electrolyte interphase (CEI) layer on the surface of the OCMs. This mitigates the direct interaction between the electrolyte and electrode materials, resolving the dissolution problem and achieving excellent cycling stability. Theoretical calculations and spectroscopic analyses indicate that the introduction of LFCs results in more fluorine-containing anions participating in the solvation structure, which further decompose to form a uniform, dense, and robust CEI layer during discharge-charge cycles. Notably, when the L3FC with strong adsorption to carbonyl materials is introduced, the resulting CEI layer provides excellent interfacial kinetics and effectively protects the cathode from electrolyte erosion. In this electrolyte, the pyrene-4,5,9,10-tetraone (PTO) cathode exhibits outstanding electrochemical performance, with a discharge capacity of 232 mA h g^-1 at a rate of 5C and capacity retention rate of 72% after 1000 cycles at 2C. This study proposes the construction of an excellent CEI layer tailored for OCMs by regulating the electrolyte composition to alleviate dissolution of electrode materials in the electrolyte, thereby significantly enhancing electrochemical performance.