Lithium All‐Solid‐State Batteries Fabricated at Room Temperature by the Powder Aerosol Deposition Method with Garnet‐Type Electrolyte and Graded Composite Cathode

Lithium‐based all‐solid‐state batteries (ASSBs) are attracting worldwide attention as the next step in the evolution of Li‐ion batteries (LIBs). They have the potential to address safety concerns and limited energy densities, which are key challenges for LIBs. The current focus is on enhancing the electrochemical properties of ASSBs. However, a suitable economic method for fabricating them remains to be established, especially when ceramic materials are used as solid electrolytes. The powder aerosol deposition method (PAD or ADM) is a ceramic processing method that uses raw ceramic powders to fabricate dense, several micrometer thick ceramic films. The entire process takes place at room temperature and in the absence of additional binders. Therefore, PAD is used in this study to fabricate ASSBs with LiNi0.83Mn0.11Co0.06O2 (NMC) as the cathode active material and Al0.2Li6.025La3Zr1.625Ta0.375O12 (LLZO) as the solid electrolyte. The cathode is fabricated as a composite with a gradient in the electrolyte concentration. The successful fabrication is confirmed through scanning electron microscopy and energy‐dispersive X‐ray spectroscopy analysis. Electrochemical characterization shows that a PAD‐ASSB can be cycled. Furthermore, it can be shown that 145 µm thick NMC films can be fabricated by PAD. The electrochemical results are compared with the theoretical potential of PAD‐ASSBs, and methods to further improve the achieved state are discussed.