(412c) Salt-Philic and Solvent-Phobic Carboxylated Polythiophene Conductive Layers for Fluoride-Rich Cathode Electrolyte Interface in Lithium-Ion Batteries

With the continuous development of energy storage technologies, lithium-ion batteries (LIBs) emerge as a pivotal role due to their superior energy density and lifespan. The electrode active material is the critical battery component, where complex interactions between the active materials and their surrounding environment directly influence both the energy output and the overall lifespan of the battery. However, the cathode electrolyte interphase (CEI) formed from traditional electrodes is non-uniform and fragile. The impact of the CEI generated by individual active materials is amplified under the bulk operational conditions of the battery, leading to rapid capacity degradation and safety concerns. Electrolyte component regulation and electrode interface engineering could enable a stable and robust CEI shield limiting damaging active material-electrolyte interactions and supporting ion transport. Thus, this shell can suppress electrochemical side reactions and prolong cycling life. Despite these recent achievements, the electrochemical performance of the state-of-the-art LIBs still cannot satisfy the rapidly increased demand for the next generation of LIBs.

To address these challenges and advance the next generation of LIBs, we developed a poly[3-(potassium-4-butanoate)thiophene] (PPBT) coated lithium iron phosphate (LFP) as the active material for highly stable LIB electrodes. PPBT, a water-soluble conjugated polymer, was selected because of its effectiveness in supporting ion and electron conduction as well as a chemical bridge for bonding on various active materials surfaces. Owing to its carboxylated side chain functionality and polythiophene backbone, PPBT exhibits distinctive salt-philic and solvent-phobic properties. Its salt-philic feature facilitates effective contact between active materials and lithium salts, while its solvent-phobic property can reduce electrolyte decomposition. The results of this study not only provide new insights into battery interface engineering but also offer practical strategies for the design and development of high-performance LIBs. Through detailed analysis of the PPBT coating layer, we demonstrate how active material surface engineering can optimize electrode interfacial interactions, thereby addressing key issues in traditional battery technology and creating a path forward to achieve improved electronic/ionic conductivity with controllable CEI formation.