Single-crystal nickel-rich materials are promising alternatives to polycrystalline cathodes owing to their excellent structure stability and cycle performance while the cathode material usually appears high cation mixing, which may have a negative effect on its electrochemical performance. The study presents the structural evolution of single-crystal LiNi0.83 Co0.12 Mn0.05 O2 in the temperature-composition space using temperature-resolved in situ XRD and the cation mixing is tuned to improve electrochemical performances. The as-synthesized single-crystal sample shows high initial discharge specific capacity (195.5 mAh g-1 at 1 C), and excellent capacity retention (80.1 % after 400 cycles at 1 C), taking account of lower structure disorder (Ni2+ occupying Li sites is 1.56 %) and integrated grains with an average of 2-3 μm. In addition, the single-crystal material also displays a superior rate capability of 159.1 mAh g-1 at the rate of 5 C. This excellent performance is attributed to the rapid Li+ transportation within the crystal structure with fewer Ni2+ cations in Li layer as well as intactly single grains. In sum, the regulation of Li+ /Ni2+ mixing provides a feasible strategy for boosting single-crystal nickel-rich cathode material.
Keywords: Nickel-rich cathodes; cation mixing; electrochemical performance; lithium-ion batteries; structural evolution.
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