Improved electrochemical performance of Li₁.₂Ni₀.₂Mn₀.₆O₂ cathode materials by ball milling and carbon coating
2013
Liu, Yunjian | Lv, Jun | Liu, Sanbin | Chen, Long | Chen, Xiaohua
Li₁.₂Ni₀.₂Mn₀.₆O₂ powders have been synthesized and then treated by ball milling and carbon coating to improve the electrochemical performance. The effect of ball milling and carbon coating on physical and electrochemical properties has been discussed through the characterizations of X-ray diffraction (XRD), scanning electron microscopy (SEM), transmission electron microscope (TEM), electrochemical impedance spectroscopy (EIS), discharge capacity and rate tests. The first discharge capacity and rate capability exhibit a great improvement for carbon-coated Li₁.₂Ni₀.₂Mn₀.₆O₂ than the pristine and ball-milled. The discharge capacities of carbon-coated cathode at 0.1 and 10C are 253 and 130mAhg⁻¹, while those of ball-milled cathode are 228 and 85mAhg⁻¹, and those of pristine Li₁.₂Ni₀.₂Mn₀.₆O₂ are only about 219 and 22mAhg⁻¹. The capacity retention of carbon-coated electrode after 50cycles is 97.8%, in compared with those of pristine and ball-milled are 95.3% and 92.8%, respectively. EIS results indicate that the charge transfer resistance (Rcₜ) of pristine electrode has been decreased from 62Ω to 35Ω after ball milling and to 23Ω after carbon coating, and the Rcₜ of pristine Li₁.₂Ni₀.₂Mn₀.₆O₂ increased faster than that of carbon-coated sample after cycles.
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