Scalable Fabrication of LiMn2O4/Polythiophene with Improved Electrochemical Performance for Lithium-Ion Batteries

Surface modification with conductive polymers has been widely used to improve the electrochemical performance of cathode materials for lithium-ion batteries. However, the conductive polymer-modified cathodes universally employ a solution-based oxidation polymerization method, making suspicious Li+ leaching of the cathodes during the modification process. In this paper, we report on a simple method for scalable fabrication of polythiophene-coated LiMn2O4 (LMO/PTh) through a room-temperature-and-pressure chemical vapor deposition approach. Thiophene can be oxidized by surface Mn4+ ions of LMO, yielding in situ PTh formation upon LMO. The resulting LMO/PTh composites are characterized with XRD, SEM, TEM, ICP-OES, XPS, and AES techniques. A thin layer of PTh with an average thickness of ca. 1.5 nm can be coated onto the LMO particles, using 300 mu L of thiophene relative to 10 g of LMO powders. The LMO/PTh-300 composite manifests improved aging resistance and electrochemical performance at both room temperature and 55 degrees C, compared with pristine LMO. The improved properties are attributed to the PTh coating, which not only functions as a moisture-buffering layer but also serves as an absorber to eliminate HF in the electrolyte.

Automated summary

In this study, a simple method for scalable fabrication of polythiophene-coated LiMn2O4 (LMO/PTh) through chemical vapor deposition approach is reported. Thiophene can be oxidized by surface Mn4+ ions of LMO, resulting in in situ PTh formation upon LMO particles. The resulting composites exhibit improved aging resistance and electrochemical performance attributed to the PTh coating as a moisture-buffering layer and HF absorber in the electrolyte.