Design, production, and characterization of three-dimensionally-structured oxide-polymer composite cathodes for all-solid-state batteries

Abstract

Inorganic all-solid-state batteries with oxide electrolytes show improved safety compared to conventional lithium-ion batteries due to the application of a non-flammable solid electrolyte. However, the currently applied production methods are unsuitable for creating oxide composite cathodes with a good interfacial contact between the solid electrolyte and the cathode active material, which limits the accessible discharge capacity. Thus, solid electrolyte matrix-supported all-solid-state batteries, for which a porous scaffold is filled with cathode active material, have recently seen increasing research interest. This publication introduces a scalable production route for a matrix-supported cell concept with a three-dimensionally-structured oxide-based composite cathode. Directed microstructures with different geometries were introduced into NASICON-type Li1.5Al0.5Ti1.5(PO4)3 oxide solid electrolyte layers via laser ablation. The obtained porous scaffold was infiltrated with various cathode slurries containing cathode active material and an ion-conducting polymer electrolyte to fabricate hybrid composite cathodes with an improved electrode-electrolyte interface. Scanning electron microscopy and energy-dispersive X-ray spectroscopy confirmed a high pore filling degree. A promising specific discharge capacity of 120.1 mAh·g−1 was achieved during electrochemical testing of a prototype all-solid-state battery with a LiNi0.6Mn0.2Co0.2O2 composite cathode and a lithium metal anode. Overall, this work serves as a proof-of-concept for the novel, matrix-supported cell design and provides insights into the production processes involved.