Binder free porous ultrafine/nano structured LiCoO2 cathode from plasma deposited cobalt

Increasing global demand for rechargeable lithium (Li) ion batteries has been driving the research on innovative processing techniques and material systems for cheaper production of battery electrodes. While cost reduction is important, obtaining desired microstructures in the active electrode material is also very critical for efficient performance of the batteries. Conventional processing of bulk scale Li-ion battery electrodes involves time consuming and multi-step processes starting from the production of active powder materials, blending with conductive additives and binders to develop the electrode material coating on a current collector. On the other hand, thin film battery technologies employ expensive vapor based or sputtering or laser ablation techniques to develop the electrodes. In this study, an innovative, rapid and a two step scalable manufacturing process has been developed. While capable of developing porous and ultrafine/nano structured oxide based LiCoO2 cathode material directly on a charge collector from metallic Cobalt (Co) coatings, the process does not require polymeric binders. Following this approach, LiCoO2 cathodes were synthesized directly on a stainless steel charge collector from plasma sprayed Co coatings via thermal treatments using aqueous LiNO3 solution. X-ray diffraction (XRD) studies confirmed presence of LiCoO2 hexagonal phase. Microstructural and phase analysis showed porous active material with ultrafine/nano structural features along with imperfections (e.g., dislocations). Electrochemical characterization illustrated an average voltage around 3.9 V with a specific discharge capacity around 70-85% of the nominal capacity (∼138 mAh/g) against Li counter electrode. However, process optimization in terms of plasma spray coatings and thermal treatments, and addition of carbon may enhance the performance of LiCoO2 electrodes. Absence of polymeric binders makes these electrodes suitable for high temperature battery applications.