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

Area of Science:

• Materials Science
• Electrochemistry
• Surface Chemistry

Background:

• Atomic layer deposition (ALD) is widely used for coating battery electrodes with metal oxides to enhance cycling stability.
• The chemical interactions between ALD precursors and electrode materials are well-studied, but their reactivity with battery binders remains largely unexplored.
• Polyvinylidene fluoride (PVDF) is a common polymer binder in battery electrodes, often assumed to be chemically inert during ALD processes.

Purpose of the Study:

• To investigate the reactivity of the polyvinylidene fluoride (PVDF) binder with trimethylaluminum (TMA), a common precursor in atomic layer deposition (ALD).
• To elucidate the chemical products formed from the interaction between TMA and PVDF.
• To reassess the chemical stability and suitability of PVDF as a binder in ALD-processed battery components.

Main Methods:

• Combined experimental and computational approach.
• X-ray photoelectron spectroscopy (XPS) was employed to analyze the surface chemistry and reaction products of PVDF exposed to TMA.
• Density functional theory (DFT) simulations were utilized to model the reaction mechanism and thermodynamics between TMA and PVDF.

Main Results:

• Density functional theory (DFT) simulations predicted an exothermic reaction between trimethylaluminum (TMA) and polyvinylidene fluoride (PVDF).
• The reaction yields methane (CH4), dimethyl aluminum fluoride, and creates nonsaturated carbons within the PVDF backbone.
• X-ray photoelectron spectroscopy (XPS) results corroborated the DFT findings, confirming the chemical transformation of PVDF upon exposure to TMA.

Conclusions:

• The study reveals that polyvinylidene fluoride (PVDF) is not chemically inert during atomic layer deposition (ALD) processes involving trimethylaluminum (TMA).
• Side reactions between TMA and PVDF occur, leading to chemical modifications of the binder.
• These findings necessitate a re-evaluation of PVDF's role and application in battery technologies utilizing ALD for electrode coatings.