Forschungsvorhaben LASIBAT

Abstract

LASIBAT aims to develop a scalable inline blue-laser sintering process for manufacturing ceramic solid-state batteries (SSBs) by addressing materials, system integration and process engineering to raise TRL from 2 to 4–5. Fraunhofer ILT focused on laser process development to produce a porous phase-pure LLZO scaffold on a metallic substrate for KAM infiltration, a dense phase-pure LLZO separator layer, and scaling both processes using line optics. LLZO pastes were screen-printed onto metal substrates and processed with blue laser radiation to form either a porous, sintered skeleton or a dense separator film, enabling layer-by-layer assembly from mixed cathode to Li-metal anode without prolonged furnace sintering. Selective, high heating rates and short interaction times minimize interlayer diffusion and reactions, overcoming LLZO's high sintering temperature relative to KAM. Initial trials revealed inhomogeneous sintering: low-sinter zones coexisted with resolidified melt spheres, attributed to temperature-dependent optical property changes. To stabilize absorption at 450 nm, laser additives were introduced, enabling absorption control between ~40% and 60%. Process parameters (power, traverse speed, line overlap) influenced phase composition: increasing energy input reduced the LLZO phase and promoted formation of insulating La2Zr2O7. Pulsed operation also led to LLZO decomposition prior to densification. System handover allowed scaled-area trials with zoom optics. The results remained suboptimal. Material adjustments by adding a Li-excess in the form of LiOH to screen-printing pastes and substrate change from stainless steel to titanium improved phase stability, likely by providing a lithium-rich local environment to stabilize cubic LLZO. Focus shifted to separator development. A high-density, phase-pure LLZO separator with low residual porosity and thermal cracking was achieved, reaching an area processing rate of 240 mm²/s, exceeding the 100 mm²/s target. Ionic conductivity measurements remained inconclusive due to residual defects. The project demonstrates laser-based sintering feasibility for LLZO separators and informs further optimization of composition, optics and thermal management toward inline scalable SSB production. Planned next steps include targeted defect mitigation, reproducibility studies, ion-conductivity validation, and integration trials combining laser-sintered layers with lithium metal handling strategies toward industrial scale-up efforts.