Interface crystal domain regulation via TiO2 surface modification enhancing stability of layered LiNi0.5Co0.2Mn0.3O2 for lithium-ion batteries

Cyclic stability is one of the key factors limiting the large-scale application of ternary materials for lithium-ion batteries. TiO2 surface-modified LiNi0.5Co0.2Mn0.3O2 is prepared by a simple method under low-temperature heat treatment to improve its cyclic stability. It is the first time to interpret the specific mechanism from the perspective of crystal domains, which is explored by X-ray diffraction (XRD), field emission scanning electron microscopy (FESEM), transmission electron microscope (TEM), energy-dispersive X-ray (EDX) mapping, and electrochemical tests in detail. The distribution of TiO2 and crystal domains are regulated, which stabilizes the interface and reduced the grain boundary, respectively. The increasing of charge transfer impedance and solid electrolyte interphase (SEI) membrane impedance is restrained, which finally improves the cycling stability. Average cycling capacity retention rates of samples with TiO2 surface modification at 0.1 C after 150 cycles and 1 C after 300 cycles are increased by 13.5% and 23%.