Dry-processed bimodal cathode with single-crystalline particles for high-density and high-performance lithium-ion batteries

Abstract

The development of high-performance and environmentally friendly cathodes is crucial for advancing the lithium-ion battery (LIB) technology. This study aims to solve the problems associated with the conventional wet electrode fabrication that uses a N-methyl-2-pyrrolidone solvent by introducing a solvent-free electrode process employing polytetrafluoroethylene binder to fabricate cathodes with Ni-rich LiNi_1-x-y-zCo_xMn_yAl_zO₂ active materials. In addition, to enhance electrode density, this study explores bimodal active materials composed of large polycrystalline (PC) and small single crystalline (SC) particles mixed in an optimal ratio. By employing bimodal cathode active materials, electrode density is easily enhanced during processing while minimizing the pulverization of the cathode materials. Furthermore, the inclusion of small SC particles promotes a more uniform dispersion of conductive additives in the electrodes and improves cell cycling performance. As a result, the full cell using bimodal materials demonstrates superior capacity retention of 80.1 % (146.4 mAh g⁻¹) compared to 64.6 % (117.3 mAh g⁻¹) for the cell with PC materials after 300 cycles. This study provides a foundation for advancing LIB cathode research and industrial applications, paving the way for future high-energy-density cathode designs.