Molecular Effects of Li-Coordinating Binders and Negatively Charged Binders on the Li Local Mobility near the Electrolyte/LiFePO Cathode Interface within Lithium-Ion Batteries.

The development of lithium-ion batteries (LIBs) is important in the realm of energy storage. Understanding the intricate effects of binders on the Li transport at the cathode/electrolyte interface in LIBs remains a challenge. This study utilized molecular dynamics simulations to compare the molecular effects of conventional polyvinylidene difluoride (PVDF), Li-coordinating polyethylene oxide (PEO), and negatively charged polystyrene sulfonate (PSS) binders on local Li mobility at the electrolyte/LiFePO (LFP) cathode interface. By examining concentration profiles of Li, three different polymer binders, and anions near Li-rich LFP and Li-depleted FePO (FP) surfaces, we found a superior performance of the negatively charged PSS on enhancing Li distribution near the Li-depleted FP surface. The radial distribution function and coordination number analyses revealed the potent interactions of PEO and PSS with Li disrupting Li coordination with electrolyte solvents. Our simulations also revealed the effects of non-uniform binder dispersions on the Li local mobility near the cathode surface. The combined results provide a comparative insight into Li transport at the electrolyte/cathode interface influenced by distinct binder chemistries, offering a profound understanding of the binder designs for high-performance LIBs.