Distinguishing Li⁺Charge Transfer Kinetics at NCA/Electrolyte and Graphite/Electrolyte Interfaces, and NCA/Electrolyte and LFP/Electrolyte Interfaces in Li-Ion Cells

In examining the Li + charge transfer kinetics at the graphite anode and the lithium nickel cobalt aluminum oxide, LiNi 0.80 Co 0.15 Al 0.05 O 2 (NCA), cathode in a full cell, we found that the activation energy, E a , for the charge transfer at the graphite/electrolyte interface is about 68 kJ/mol, which is consistent with recently reported values. However, the E a for the charge transfer at the NCA/electrolyte interface is about 50 kJ/mol, which is lower than at the graphite anode. With desolvation as the predominate step for limiting the kinetics and both electrodes subjected to the same electrolyte, the difference in E a suggests that it is greatly influenced with respect to the nature of the electrode materials and their associated SEIs. This is further confirmed by the examination of Li + charge transfer at the LiFePO 4 (LFP)/electrolyte and the graphite/electrolyte interfaces using a LFP/graphite full cell.