Engineering a high-performance low-cobalt single crystalline Li1.2Ni0.167Co0.067Mn0.567O2 cathode material for lithium-ion battery

Abstract

Li-rich manganese-based layered oxides (LRM) can be regarded as the next-generation cathode materials for high-energy-density Li-ion batteries. The single crystalline LRMs make it have the potential to further application due to the higher compaction density and the absence of intergranular cracks. However, it can't meet the requirements for high energy density cathode materials because of its poor discharge capacity and unsatisfactory stability. In this study, we demonstrate the F doped single-crystal LRM (F-LRM) with the size is >800 nm giving an initial discharge capacity of 309 mAh g−1 at current density of 0.1 C (25 mA g−1) and the capacity retention is reaching up to 97.4 % after 100 cycles. Additionally, its rate capability is up to 206 mAh g−1 under 250 mA g−1 with 90.6 % and 80.6 % retention after 300 and 500 cycles, respectively. X-ray Diffraction (XRD), X-ray Photoelectron Spectroscopy (XPS) and Raman indicated that the F-doped LRM forms strong TM-F bonds and creates a suitable oxygen vacancies (OVs) concentration. Furthermore, operando Differential Electrochemical Mass Spectrometer (DEMS) and High-resolution Transmission Electron Microscopy (HRTEM) analysis revealed that O2 for F-LRM does not appear during the (de)lithiation with the layered structure maintained after cycling. The design of high-performance, low-cobalt single crystal materials offers a novel approach for the future development of lithium-rich cathodes.