Various Solvent-Binder Compositions and their Crystalline Phase for Optimal Screen-Printing of NMC Cathodes

Abstract

This research examines the compatibility and performance of various solvents and binders in the battery cathode fabrication. The study focused on the applicability of solvents, including DMF, NMP, p-Xylene, Ethanol, Toluene, Cyrene, and KJCMPA, in conjunction with binders such as PVDF #9300, PVDF #1100, HSV 1810, PVP, Oppanol N150, and Oppanol B15 for NMC-based slurry formulation. Each solvent-binder combination was evaluated with NMC material, and those demonstrating optimal solubility, adhesion, and film quality were selected for cathode screen-printing trials. Results show that the combination of NMP solvent and HSV 1810 binder outperformed other pairings in cycling stability and capacity retention, achieving 87 % capacity retention after 1,000 1C/1C cycles. Comprehensive analyses using SEM, XRD, and FTIR offered insights into the structural and binder phase characteristics of the fabricated cathodes, especially the alterations in binder crystallinity phases (α, β, and γ). The data suggest that the use of the homopolymer HSV 1810, irrespective of the solvent, results in a pronounced presence of the γ-phase within the binder, which subsequently improves battery performance. Moreover, the findings underscore the importance of the solvent-binder combinations in enhancing battery performance and longevity.