Electrode−electrolyte interfaces (EEIs) affect the rate capability, cycling stability, and thermal safety of lithium-ion batteries (LIBs). Designing stable EEIs with fast Li + transport is crucial for developing advanced LIBs. Here, we study Li + kinetics at EEIs tailored by three nanoscale polymer thin films via chemical vapor deposition (CVD) polymerization. Small binding energy with Li + and the presence of sufficient binding sites for Li + allow poly(3,4-ethylenedioxythiophene) (PEDOT) based artificial coatings to enable fast charging of LiCoO 2 . Operando synchrotron X-ray diffraction experiments suggest that the superior Li + transport property in PEDOT further improves current homogeneity in the LiCoO 2 electrode during cycling. PEDOT also forms chemical bonds with LiCoO 2 , which reduces Co dissolution and inhibits electrolyte decomposition. As a result, the LiCoO 2 4.5 V cycle life tested at C/2 increases over 1700% after PEDOT coating. In comparison, the other two polymer coatings show undesirable effects on LiCoO 2 performance. These insights provide us with rules for selecting/designing polymers to engineer EEIs in advanced LIBs.

Measuring the thermal conductivity of oxidative chemical vapor deposited poly(3,4-ethylenedioxythiophene) thin films.

The effect of electromagnetic fields on nanoscale atomic structure was determined using synchrotron X-ray pair distribution function (PDF) analysis.

In situ pair distribution function analysis reveals that electromagnetic radiation exposure during SnO2 nanoparticle growth alters local atomic structure and the synthetic pathway compared to conventional hydrothermal synthesis routes.