Engineering high performance LiNi0·8Co0·1Mn0·1O2 cathodes through controlling fabrication methods

The demand for high-energy Li-ion batteries has spurred extensive research on Ni-rich layered cathode materials, particularly LiNi_0·8Co_0·1Mn_0·1O₂ (NMC811). However, challenges such as cation mixing and structural instability persist, hindering their widespread application. This study investigates the synergistic effects of co-precipitation and high-energy ball milling techniques on the physicochemical and electrochemical properties of NMC811 cathode materials for lithium-ion batteries. By meticulously controlling ammonia concentration during co-precipitation, a uniform particle distribution within the precursor material was achieved. Subsequent high-energy ball milling further refined the material, promoting a reduction in particle size and an increase in oxygen vacancy concentrations, as confirmed by different characterizations. These structural modifications resulted in enhanced electrochemical performance, including improved rate capability and cycling stability. Electrochemical Impedance Spectroscopy confirmed these enhancements, revealing a significantly higher Li-ion diffusion coefficient and reduced interfacial resistances for the ball-milled sample, compared to NMC811 synthesized without ball milling. The ball-milled NMC811 exhibited a higher capacity retention of 81 % after 100 cycles at 0.5C, compared to 69 % for the non-ball-milled sample. This improvement is attributed to the reduced particle size and increased oxygen vacancies, which facilitate faster lithium-ion diffusion, as directly supported by the increased D_Li, and enhanced structural stability, partly by mitigating detrimental phase transitions like the H2–H3 transition during cycling. The findings underscore the potential of combining co-precipitation with high-energy ball milling as a viable strategy for developing high-performance NMC811 cathodes for advanced lithium-ion battery applications.