Synergistic high-shear pH-regulated precipitation and selenium modification for boosting the electrochemical performance of LiNi0.9Mn0.1O2 cathodes

To enhance the electrochemical performance of high-nickel and cobalt-free cathode material LiNi 0.9 Mn 0.1 O 2 (NM), this study proposes a synergistic strategy integrating high-shear pH-regulated precipitation to fabricate uniform micron-sized structured precursors, with Se-surface modification to enhance the cycling stability. First, the optimal sample NM-8.1 was synthesized via high-shear precipitation with the controlling pH value of 8.1, exhibiting the initial discharge capacity of 208.3 mAh g −1 at 25 °C and 0.1 C (2.7–4.4 V) and the capacity retention of 79.9% after 200 cycles at 1 C. Then, Se-driven surface coating was prepared to improve the cycle stability for NM-8.1, and the optimized NM-1Se shows the initial discharge capacity of 210.7 mAh g −1 (25 °C, 0.1 C, 2.7–4.4 V), the capacity retention of 88.5% after 200 cycles (1 C) and 82.3% after 500 cycles at 5 C. After 200 cycles (1 C), the R ct value equals 60.42 Ω for NM-8.1, whereas 29.08 Ω for NM-1Se. X-ray diffraction (XRD), high-resolution transmission electron microscopy (HRTEM), scanning electron microscopy (SEM), cyclic voltammetry (CV) and electrochemical impedance spectroscopy (EIS) analyses indicate that both the uniform, micron-sized structured precursors and the Se modification can promote Li + diffusion, stabilize the lattice oxygen and decelerate the growth of charge transfer impedance, thereby enhancing the cycling stability of the cathode material. This work offers a generalizable paradigm for the synthesis of advanced electrode materials, providing valuable guidelines for optimizing the preparation of other high-energy-density batteries. Graphical abstract Synergistic pH-regulated precipitation and Se surface modification enhance the capacity, cycling stability, and reaction kinetics of cobalt-free Ni-rich cathodes for high performance lithium-ion batteries.