Pre-lithiated Li(Ni_<i>x</i>Mn_<i>y</i>Co_<i>z</i>)O₂ nanoparticles with a double-layer lithium structure

Li(Ni x Mn y Co z )O 2 cathode materials (NMC) have advantages such as the good Li ion diffusivity, stable reversible capacity, and environmental compatibility in spite of a low actual capacity. Although a double-layer lithium structure can be generated by pre-lithiation, the thickness is very small and the capacity improvement is limited. In this work, a series of Li([Formula: see text][Formula: see text][Formula: see text])O 2 nanoparticles are prepared by the sol–gel method and centrifugation and the pre-lithiation process are monitored by transmission electron microscope (TEM). A double lithium structure of about 10 nanometers thick is produced on the NMC materials with different sizes. With decreasing NMC particle size, the proportion of the double-layer lithium structure increases and reaches 48% for a particle diameter of 100[Formula: see text]nm. The results reveal a viable means to improve the capacity of NMC materials in charging and discharging.