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

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.