Enhanced Electrochemical Performance of Li-Rich Layered Cathode Materials by Combined Cr Doping and LiAlO2 Coating

A Li-rich layered cathode material Li 1.2 Ni 0.2 Mn 0.6 O 2 with enhanced electrochemical performance has been fabricated by combining the Cr doping and LiAlO 2 coating. The structural characterization shows the perfect layered crystal structure. The 3 wt % LiAlO 2 -coated Li 1.2 Ni 0.16 Mn 0.56 Cr 0.08 O 2 shows the highest discharge specific capacity and the best cycling stability among different coating levels. The first discharge specific capacity is enhanced from 230.4 mAhg –1 to 268.8 mAhg –1 . The capacity retention ratio is improved from 92.7% to 97.3% after 100 cycles. The spinel phase is suppressed effectively in the 3 wt % LiAlO 2 -coated Li 1.2 Ni 0.16 Mn 0.56 Cr 0.08 O 2 . The midpoint voltage value of Li 1.2 Ni 0.2 Mn 0.6 O 2 after 100 cycles is enhanced from 2.746 to 3.128 V with Cr doping and LiAlO 2 coating. The lower R ct (charge transfer resistance) and higher D Li + (ion diffusion coefficient) of 3 wt % LiAlO 2 -coated Li 1.2 Ni 0.16 Mn 0.56 Cr 0.08 O 2 contribute to the excellent rate capability. The results suggest that ion doping combined with fast ion conductor coating is an effective way to enhance the electrochemical properties of the Li-rich layered cathode materials.