2.3. Cathode Fabrication and Cell Assembly

LiFePO₄, Super P, polyvinylidene fluoride (PVDF) in the weight ratio of 8:1:1 was dispersed in NMP and vigorously stirred for 6 h. The uniform slurry was cast onto the carbon-coated aluminum foils and dried under vacuum at 100 °C for 12 h to obtain the cathode foil. The CR2025-type cells were assembled for different test: LFP/solid electrolyte/Li, Li/solid electrolyte/Li (SE), steel sheet/solid electrolyte/steel sheet (SS), carbon paper electrode/solid electrolyte/Li (CL). Taking the LiFePO₄/Li coin cells as an example. The LiFePO₄/Li coin cells were assembled in the order of “positive electrode shell—LFP electrode—polymer solution—supporting membrane—lithium anode—steel sheet—shim—negative electrode shell”; specifically, the polymer solution was directly drop-coated onto the cathode, and the volatile solvent evaporated to form an electrolyte film on the cathode. Then, a support film was placed on top, allowing a small amount of electrolyte to infiltrate the electrode, creating a concentration gradient between the positive electrode and the electrolyte to enhance interface compatibility. The entire step was finished in an Ar-filled glove box (Mikrouna, Shanghai, China) with O₂ and H₂O contents below 0.1 ppm. After assembly, the cells were placed in a 60 °C blast oven for 24 h to enhance the interface stability between the electrode and electrolyte.