Effects of Surfactants on Al2O3-Modified Li-Rich Layered Metal Oxide Cathode Materials for Advanced Li-Ion Batteries

In this work, a series of Li-rich layered metal oxides (LLMO) were prepared by the coprecipitation method for use as cathode materials in lithium ion batteries. Various surfactants were used for the preparation of Al2O3-modified LLMO. The roles of surfactants were systematically investigated to reveal the mechanism of Al2O3 modification. The microstructure and morphology of the as-prepared samples were studied by the X-ray diffraction (XRD), scanning electron microscopy (SEM), and transmission electron microscopy (TEM). The electrochemical performance was evaluated by means of cyclic voltammetry, galvanostatic charge/discharge, and electrochemical impedance spectroscopy. The experimental results showed that Al2O3 nanoparticles were uniformly dispersed on the LLMO surface using N, N, N-trimethyl-1-dodecanaminium bromide (DTAB) as the surfactant, to obtain an initial discharge capacity of 186 mAh.g(-1) at the current density of 600 mA.g(-1). After 500 cycles, the reversible discharge capacity was 132 mAh.g(-1) with a satisfactory capacity retention of 71%. Moreover, the voltage fading of the LLMO was greatly suppressed after Al2O3 modification. Therefore, the Al2O3-modified LLMO exhibited superior electrochemical performances compared with unmodified LLMO.