Ultrahigh-Loading Dry-Process for Solvent-Free Lithium-Ion Battery Electrode Fabrication

The current LIB electrode fabrication process relies heavily on the wet coating process, which uses the environmentally harmful and toxic N-methyl-2-pyrrolidone (NMP) solvent. Aside from being non-ecofriendly, this expensive organic solvent substantially increases the cost of battery production, as it needs to be dried and recycled throughout the manufacturing process. Furthermore, NMP is flammable and known to cause male infertility; thus, prolonged exposure can pose health risks to workers and present fire hazards. For this reason, achieving a completely solvent-free process for electrode fabrication is currently a unified goal for many battery researchers and manufacturers. Here, we report an industrially viable and facile dry process for LIB electrodes, namely, the dry press-coating process using multiwalled carbon nanotubes (MWNTs) and polyvinylidene fluoride (PVDF) as a dry powder composite and etched Al foil as a current collector. The MWNT-PVDF dry powder composite uniquely forms a robust 3D conductive scaffold that houses the active materials upon pressing, and the submicron pore-covered etched Al current collector provides remarkable adhesion to the interlayer. Notably, the mechanical strength and performance of the fabricated LiNi_0.7Co_0.1Mn_0.2O₂ (NCM712) dry press-coated electrodes (DPCEs) far exceed those of conventional slurry-coated electrodes (SCEs) and give rise to ultrahigh loading (71 mg cm^-2, 13.2 mAh cm^-2) with impressive specific energy and volumetric energy density of 372 Wh kg^-1 and 763 Wh L^-1, respectively.