The Influence of Thick Cathode Fabrication Processing on Battery Cell Performance

The lithium-ion battery (LIB) is the key energy storage device for electric transportation. The thick electrode (single-sided areal capacity >4.0 mAh/cm2) design is a straightforward and effective strategy for improving cell energy density by improving the mass proportion of electroactive materials in whole cell components and for reducing cost of the battery cell without involving new chemistries of uncertainties. Thus, selecting a low-cost and environmentally friendly fabrication process to achieve a thick cathode electrode with good electrochemical performance is of strong interest. This study investigated the impact of fabrication processes on the performance of thick LiNi0.75Mn0.25O2 (NM75) cathode electrodes in pouch cells. Two fabrication methods were compared: the conventional polyvinylidene fluoride (PVDF)-based slurry casting method (C-NM75) and the polytetrafluoroethylene (PTFE)-based powder fibrillating process (F-NM75). The pouch cells with F-NM75 electrodes exhibited significantly improved discharge and charge rate capabilities, with a discharge capacity ratio (3 C vs. C/3) > 62% and a charge capacity ratio (2 C vs. C/3) > 81%. Furthermore, F-NM75 cells demonstrated outstanding C/3 cycling performance, retaining 86% of discharge capacity after 2200 cycles. These results strongly indicated that the PTFE-based powder fibrillating process is a promising solution to construct high-performance thick cathode electrodes for electric vehicles (EVs) applications.