Charge Transport Limitations to the Power Performance of LiNi 0.5 Mn 0.3 Co 0.2 O 2 Composite Electrodes with Carbon Nanotubes
Résumé
The power performance of EV-designed LiNi0.5Mn0.3Co0.2O2 (NMC 532)/PVdF/CB-CNT based electrodes with 25 mg.cm(-2) active mass loading, 3.4 g.cm(-3) density, 23.5% porosity and 96:1.8:2.2 wt% composition, were measured at 0 degrees C, 22 degrees C and 40 degrees C. The CB/CNTs ratio is 100:0 or 50:50 v%. The polarization resistance and the discharge capacity are improved by using the CB-CNTs blend especially at 0 degrees C and 40 degrees C. The shape factor of the CNTs favor the electronic wiring of the active mass at 0 degrees C by forming conductive bridges over the resistive grain boundaries at the surface of NMC clusters. At 40 degrees C, the CNTs favor both the electronic and the ionic wirings of the active mass. At this temperature, the swelling of the CB/PVdF domains could be responsible for the degradation of the electrons transfer and ions transport through the electrode. This detrimental phenomenon is mitigated with the CB/CNTs blend likely due to the CNTs shape factor.