Enabling ultra-fast charging for Ni-rich LiNi0.88Co0.09Mn0.03O2 cathode by bulk W-doping

Abstract

W-doped Ni-rich LiNi0.879Co0.088Mn0.030W0.003O2 cathode material for lithium-ion batteries (LIBs) is synthesized from a bulk W-doped Ni0.879Co0.088Mn0.03W0.003(OH)2 precursor. Comparative study between the W-doped cathode and its undoped counterpart LiNi0.88Co0.09Mn0.03O2 is implemented. X-ray diffraction indicates that the W-doping shows no obvious influence on the crystallographic structure. Scanning electron microscope measurements indicate that the W-doped material has coarsened primary particles. Electrochemical evaluations reveal that the electrochemical performance is significantly improved by a small amount of W-doping, especially for the rate capability. The W-doped cathode delivers an initial discharge capacity of 201.7 mAh g−1, which is slightly higher than that of the undoped one (197.5 mAh g−1). When tested at 20C, the W-doped sample still has a discharge capacity of about 140 mAh g−1, whereas the value of the undoped one is only 104 mAh g−1. Furthermore, cyclic voltammetry and electrochemical impedance spectra measurements suggest that the W-doping can stabilize the H2 → H3 phase transition, as well as suppress the impedance increase during cycling process.