Cold Co-Sintering Studies of Composite Cathode for All Solid-State Li Batteries

In the present work, we applied cold sintering for the processing of Li1.3Al0.3Ti1.7(PO4)3 (LATP) and then LiMn2O4/LATP/Carbon black composite cathode. Their high-temperature processing is challenging due to Li evaporation and undesirable diffusion between electrode and electrolyte, leading to high interfacial resistance between these components. Cold sintering can be an option to address these problems. For cold sintered LATP, X-ray diffraction analysis displayed only a minor amount of secondary phases, X-ray photoelectron spectroscopy showed slight reduction of Ti+4 to Ti+3 and Arrhenius plot presented higher activation energy for Li+ conduction. Transferring this knowledge to our composite cathode, we got ∼85% relative density at merely 400 °C, 400 MPa using 1 molar aqueous solution of LiOH in a 1 min dwell time. To the best of our knowledge this is the first time a cold co-sintered composite cathode of this type has been prepared. It was wetted with polymer electrolyte and characterized electrochemically against a Li-metal anode. While the cell could be reversible cycled several times, proving the concept, impurity phases after cold sintering limited the extractable capacity. This detailed investigation contributes a deep insight of cold co-sintering application for composite cathodes.