The Impact of PTFE:PVDF Ratio on the Fabrication of Free-Standing Electrodes for Solvent-Free Dry Electrodes in Libs

The current wet process of LIB electrode fabrication presents several challenges, including the use of the environmentally toxic and harmful N-methyl-2-pyrrolidone (NMP) solvent and non-uniform binder distribution due to the capillary force of the drying process. In addition, it is difficult to increase the thickness of the electrode and leads to relatively low-capacity electrodes. To address these issues, solvent-free dry electrode processes are promising. In the dry electrode process, binders play crucial roles in free-standing electrode formation. Fibrillization of Polytetrafluoroethylene(PTFE) occurs at a temperature of about 19 ℃, and the shear force of high temperature and high pressure helps to maintain the shape of the free-standing electrode. In this study, we performed a comparative analysis through the physical blending of PTFE and PVDF polymer binders with different ratios. A variety of characterization tools are used to investigate the optimal ratio that ensures good cycle performance for high-loading cathode electrodes while maintaining free-standing electrodes: 180° peel test, sheet-resistance test, SAICAS, FE-SEM, and electrochemical performance tests Keywords : Solvent-free, Dry electrode; electrode fabrication; PTFE polymer binder, Fibrillization, Lithium ion batteries Figure 1