Fully Aqueous-Processed Li-Ion Electrodes with Ultra-High Loading and Potential for Roll-to-Roll Processing

Abstract

In this study, high- and ultra-high-loading NMC622-based cathodes (7.0 and 18.0 mAh/cm²) and graphite-based anodes (9.0 and 22.5 mAh/cm²) were prepared by using a porous carbon structure as current collector. All electrodes in this work were prepared by an NMP-free, PFAS-free and scalable process. Full cells with areal capacities of 7 mAh/cm² and 18 mAh/cm² were assembled and tested. The results show an excellent cycling stability, reaching up to 950 cycles at 10 mA/cm² for the cells with ultra-high-loading electrodes (capacity 18 mAh/cm²) and 650 cycles at 8 mA/cm² for the cells with high-loading electrodes (capacity of 7 mAh/cm²). The influence of cathode porosity on the electrochemical performance in cells capacity of 7 mAh/cm² showed that a lower porosity leads to a poorer rate capability as well as a worse cycling capability (400 cycles at 6 mA/cm²). Post-mortem analysis reveal that the anode aging is more pronounced during full cell cycling. Further the scalability of the production process was demonstrated by using a padder tool. With that, cathodes with a loading of 5 mAh/cm² were produced in a roll-to-roll process.