Polyvinylidene Fluoride (PVDF)–Trimethylaluminum (TMA) Chemistry: First-Principles Investigation and Experimental Insights

Abstract

Atomic layer deposition (ALD) is a popular method of coating battery electrodes with metal oxides for improved cycling stability. While significant research has focused on the interaction between the reactive metal alkyl precursor and the electrode materials, little is known about the reactivity of the precursor toward other components of the battery electrode, such as the polymer binder. This study presents a combined computational and experimental investigation of the reaction between the popular polyvinylidene (PVDF) binder and the trimethylaluminum (TMA) precursor commonly used for coating Al₂O₃ by ALD. X-ray photoelectron spectroscopy (XPS) was used to interrogate the reactivity of PVDF toward TMA and to characterize the reaction products. Density functional theory (DFT) simulations identified an exothermic reaction of TMA with PVDF, yielding methane (CH₄), dimethyl aluminum fluoride, and nonsaturated carbons at the reaction site in the PVDF backbone, which is well aligned with XPS results. The newfound chemistry involving TMA and PVDF reveals that PVDF undergoes side reactions in ALD, contradicting the previous belief that PVDF is chemically inert as a battery binder. This discovery prompts a reassessment of PVDF’s application scenarios in the battery industry.