Fluorine-free water-based Ni-rich positive electrodes and their performance in pouch- and 21700-type cells

Abstract

In recent years substantial progress has been made in the lab-scale aqueous processing of cathode electrodes containing Ni-rich active materials such as LiNi0.83Co0.12Mn0.05O2. Now it has to be proven in production-scale that such an environmentally-friendly, water-based process will deliver cells with competitive performance. We demonstrate the upscaling of a carboxymethyl cellulose and styrene-butadiene rubber based electrode-coating recipe from 250 mL lab-scale to 10 L production-scale by coating a double-sided electrode with 140 m length, very homogeneous mass loading, and excellent roll to roll processability. Several challenges such as the control and stabilization of slurry pH and fine adjustment of the mixing and coating time have been solved. The organic- and H2O-based pilot scale cathode electrodes with areal capacities of 3.0 mAh cm−2 were characterized in pouch- and 21700-type cylindrical cells. The cells were cycled at room temperature and 45 °C for up to 2000 cycles at 1C/1C. Pouch cells containing H2O-based electrodes show a high capacity retention of 79.3% after 1000 cycles. Similarly, H2O-based electrodes built into 21700-type cells with 3.5 Ah capacity achieved 80% after 1000 cycles at 1C/1C cycling.