The challenges, solutions and development of high energy Ni-rich NCM/NCA LiB cathode materials

Abstract

In the last three decades, the successful application of lithium ion batteries (LIB) for consumer electronics has laid solid foundation for the rapid development of large format batteries for electric vehicles (EV) and energy storage systems (ESS). Up to now, in most of the commercial LIB, carbon material, e.g. graphite is used as anode material, while the cathode material changes from spinel LiMn2O4 (LMO), olivine LiFePO4 (LFP), to layer-structured material LiNi1-x-yCoxMnyO2, and LiNi1-x-yCoxAyO2 (NCA), in order to get increased gravimetric and volumetric energy density. By combining the merits of the high capacity of lithium nickel oxide (LiNiO2), with the good rate capability of lithium cobalt oxide (LiCoO2), and the thermal stability and low cost of lithium manganese oxide (LiMnO2), lithium nickel cobalt manganese oxide (LiNi1-x-y CoxMnyO2, NCM) enjoys outstandingly comprehensive advantages, and turns to be the major cathode material for lithium ion batteries. One way to increase the energy densityof NCM/NCA materials is to increase the Ni content and thus lowering the Co/Mn(Al) content, another way to get high energy density is to increase the charging cut-off voltage. High energy NCM/NCA materials are confronted more challenging issues, like degradated cycle life, severe swelling upon thermal storage, and safety problems. This paper will address such issues, and put forward some feasible solutions.