Laser sintering of ceramic-based solid-state battery materials

Summary:

Solid-state batteries are a promising technology for high travelling ranges and safety in future electromobility. In a solid-state battery, separator and liquid electrolyte materials are combined to one solid-state electrolyte layer. Suitable ceramic materials are lithium lanthanum zirconate (LLZ) as electrolyte and lithium cobalt oxide (LCO) as cathode active material. For the cathode layer, a combination of LCO and LLZ is aspired to have ionic conductivity in the “mixed” cathode layer. This would improve the battery performance.
The approach to produce a ceramic battery cell is to functionalize the different screen-printed layers made of ceramic micro particles by laser sintering. Conventionally, sintering is done in an oven process. A main disadvantage is the diffusion of materials into adjacent layers due to long process times (in the range of minutes) at high temperatures. Furthermore, layer stacks consisting of materials with incompatibilities in decomposition temperatures cannot be treated successfully.
Preservation of the crystal structure and a suitable temperature management during the sintering process are of enormous importance. By means of laser processing, short interaction times within the range of seconds and below are realised. High heating rates show potential for reducing diffusion processes and preserving the crystal structure of the materials.
In this work, a scalable laser sintering process of a battery half-cell is presented. By means of screen printing, the mixed cathode material is applied on a metallic current collector foil. The influence of different interaction times is investigated. The ionic conductivity of the mixed cathode layer is measured to demonstrate the influence of electrolyte particles on the ionic conductivity.