Indexed on: 15 Feb '17Published on: 15 Feb '17Published in: Analytical Chemistry
Nickel Manganese Cobalt oxide (NMC) is a high energy capacity cathode material that attracts the interest of many research groups. Coating a protection layer on the NMC surface is one approach to improve its cycling and safety performance. However there is no standard and consistent way to characterize the coating performance (thickness) of this protection layer, especially due to the nano-scale of primary particle and spherical morphology of the secondary particle. In this paper, a novel empirical method based on Energy Dispersive X-ray Spectroscopy (EDX) analysis at low accelerating voltage is proposed to evaluate the protection layer thickness on the scale of tens of nanometers. The layer thickness is characterized by measuring the intensity decrease of a substrate element due to absorption by overlying coating layers. An internal standard coating (metal layer) is applied to mimic the morphology influence and improve the accuracy of thickness quantitation. For the model sample evaluation, carbon layer coating 1 to10 nm thick were successfully quantified by this method.