Mechanism exploration of enhanced electrochemical performance of single-crystal versus polycrystalline LiNi0.8Mn0.1Co0.1O2

Single-crystal LiNi 0.8 Mn 0.1 Co 0.1 O 2 (SC-811), which offers better cycle performance compared to the polycrystalline counterpart, has received great attention. We report herein the synthesis of SC-811 with a grain size of 2–4 μm by washing and reheating method, which compares with conventional polycrystalline LiNi 0.8 Co 0.1 Mn 0.1 O 2 (PC-811). The discharge capacity of SC-811 reaches 152.1 mAh·g −1 after 100 cycles (86.7% capacity retention) at 1.0C, which is much better than that of PC-811 (130.2 mAh·g −1 , 73.8% capacity retention). By using multiscale characterization, the results unveil that SC-811 can not only improve the reversibility of the H2-H3 phase transitions, suppress the generation of micro-cracks and phase transformations, but also mitigate the undesired side reactions between electrode and electrolyte. Besides, the Li–O bond of SC-811 is longer than that of PC-811, which is conducive to the de-intercalation of Li-ions, thereby enhancing the structural stability. This finding provides an impressive strategy to sustain structural stability and improve the cycling life of Ni-rich layered cathodes. Graphical abstract