Tailoring Electrode-Electrolyte Interfaces in Lithium-Ion Batteries Using Molecularly Engineered Functional Polymers.

Area of Science:

• Materials Science
• Electrochemistry
• Polymer Chemistry

Background:

• Electrode-electrolyte interfaces (EEIs) critically influence lithium-ion battery (LIB) performance, affecting rate capability, cycling stability, and safety.
• Developing stable EEIs with efficient Li+ transport is essential for advanced LIBs.

Purpose of the Study:

• To investigate Li+ kinetics at EEIs modified by nanoscale polymer thin films.
• To evaluate the impact of different polymer coatings on LiCoO2 electrode performance for LIBs.

Main Methods:

• Chemical vapor deposition (CVD) polymerization for creating nanoscale polymer thin films.
• Operando synchrotron X-ray diffraction to study Li+ transport and electrode behavior.
• Electrochemical testing of LiCoO2 electrodes with polymer coatings.

Main Results:

• Poly(3,4-ethylenedioxythiophene) (PEDOT) coatings demonstrated superior Li+ transport due to optimal binding energy and sites.
• PEDOT coatings improved current homogeneity, reduced cobalt dissolution, and inhibited electrolyte decomposition.
• LiCoO2 electrodes with PEDOT coatings exhibited a >1700% increase in 4.5 V cycle life at C/2.
• Other polymer coatings showed detrimental effects on electrode performance.

Conclusions:

• PEDOT-based artificial coatings enable fast charging and enhance the cycle life of LiCoO2 electrodes.
• The study provides guidelines for selecting and designing polymers to engineer stable and efficient EEIs for advanced LIBs.