Development of Large Area All Solid-State Lithium-Ion Cells Using Scalable and Manufacturable Coating Processes

The NREL team has fabricated all solid-state full cells with sulfide-based electrolytes using fabrication techniques suitable for high speed/low-cost manufacturing, such as slurry and tape casting. Slurry coating is a well-established and cost-effective process feasible for large scale/continuous process (e.g., roll-to-roll processing). However, most solid-state cells fabricated to date have been small area (1 cm 2 ) cells with single mAh capacities. These cells are generally fabricated by dry mixing of powders and compressing layers to hundreds of MPa up to GPa of pressure and high temperatures to condense powders into a coin-cell size battery. The use of such high pressures is not suitable for large-scale manufacturing. Further, the separator layer in this configuration is often prohibitively thick (hundreds of microns) resulting in poor rate capability and low energy density. NREL has demonstrated ability to cast thin (100 micron) electrically isolating sulfide-based separator layers and composite solid-state cathodes. Functioning large-area cells (30 cm 2 ) have been fabricated by punching out sections of cast layers to make cells tested at modest pressures. The chemical reactivity of sulfide-based electrolytes with solvents for casting and active cathode oxide materials (NMC, NCA, etc.) is particularly challenging. Figure below shows all solid-state cathode (left) and anode/argyrodite separator (right) having dimensions of 5X6 cm. The anode, cathode, and separator all use a chloride argyrodite electrolyte (Li 6 PS 5 Cl). The anode active material is graphite and cathode is alumina coated NMA with high specific capacity (> 200 mAh/g). Initial performance testing will be shared. Figure 1