Revealing the materials, design, and performance of Ni-rich LiNi1-x-yCoxMnyO2/graphite pouch cells

Abstract

Among lithium-ion batteries (LIBs), Ni-rich LiNi1-x-yCoxMnyO2/Graphite batteries hold a dominant position in electric vehicles due to high energy density, good cycling stability, and low content of Co element. In this work, Ni-rich LiNi1-x-yCoxMnyO2 (LiNi0.83Co0.07Mn0.10O2, NCM83)/Graphite pouch cells with a capacity of around 2.1 Ah are designed and manufactured. The structure and micromorphology of NCM83 as well as graphite are revealed. The XRD Rietveld refinement method clarifies the lattice parameters of NCM83. The PE separator modified by Al2O3 and PVDF (PE/Al2O3/PVDF) is used in the cells. The design parameters, formation, and aging processes are disclosed as well. Charge-discharge tests demonstrate that the NCM83/Graphite pouch cells have good electrochemical performance. Notably, the cell delivers an initial discharge capacity of 2.158 Ah at 1 A and 25 °C, and retains a high reversible discharge capacity of 1.715 Ah after 500 cycles with a capacity retention of close to 80 %. Additionally, the polarization characteristics during charging and discharging are discussed in detail, demonstrating that a good linear relationship exists between polarization voltage and cycle number. This work systematically reveals the materials, and design technology of NCM83/Graphite battery cells and helps deepen the understanding of commercial LIBs based on Ni-rich LiNi1-x-yCoxMnyO2 cathode materials.