Characterization of low-temperature solution-processed LiCoO2 thin-film cathode with molecular weight control of polyvinylpyrrolidone

Numerous LiCoO2 cathode thin-films have been prepared for all-solid-state thin-film battery applications. Preparation methods include sputtering, pulsed laser deposition, electron beam evaporation, screen printing, and spin coating. When compared to vacuum deposition methods, the solution-processed fabrication methods could result in significant cost savings and large-area production. Unfortunately, high-temperature annealing (Tanneal > 700 °C) of LiCoO2 cathode thin film is usually crucial for achieving a high performance layered phase. Here, we report on phase control of spin-coated LiCoO2 thin film by varying the molecular weight of polyvinylpyrrolidone (PVP) at low temperature. We could achieve thick and smooth film morphology by optimizing the PVP molecular weight. This method could be a promising cathode layer for low-cost thin-film batteries.