Synthesis of Cobalt-Free, Low-Cost Layered LiNi0.6Mn0.2Fe0.2O2 (NMF622) Cathode Electrodes for Next Generation Lithium-Ion Batteries

Abstract

In this research, we synthesized LiNi0.6Mn0.2Fe0.2O2 (NMF622) cathodes by substituting iron for cobalt in the cathode electrodes, which are typically associated with the chemistry of LiNi0.6Mn0.2Co0.2O2 (NMC622) cathode material used in lithium-ion batteries (LIBs). The production of NMF622 nanoparticles was achieved using the sol-gel method, incorporating metal salts as key components for structure formation. We meticulously examined the structure of NMF622 nanoparticles and electrodes through X-ray diffraction (XRD) and field emission scanning electron microscopy (FESEM), revealing the absence of impurities in the NMF622 nanopowders. Our FESEM analysis further determined particle sizes ranging from 30 to 110 nm. To evaluate the performance of NMF622 cathodes, we conducted galvanostatic charge and discharge tests at a rate of 1C within the potential range of 2.0 to 4.6 volts. Notably, the NMF622 cathodes exhibited various capacities at different rates, including 211.86, 206.07, 198.68, 191.56, 167.16, 154.99, 135.62, 115.96, 188.36, 195.36, 202.46, and 209.3 mAh/g at different C-rates. Electrochemical impedance tests indicated that all resistance values increased with the number of cycles. This study represents a significant development and evaluation of NMF cathodes, which are proposed as an alternative to NMC chemistry. As a result, it led to a substantial 60% reduction in cell manufacturing costs compared to NMC chemistry. Furthermore, the environmentally conscious choice of using iron instead of cobalt, along with the use of water-soluble binders, contributed to a reduction in toxicity.