Enhanced electrochemical performance of Li-rich layered cathode materials by combined Cr doping and LiAlO2 coating

A Li-rich layered cathode material Li1.2Ni0.2Mn0.6O2 with enhanced electrochemical performance has been fabricated by combining the Cr doping and LiAlO2 coating. The structural characterization shows the perfect layered crystal structure. The 3 wt% LiAlO2 coated Li1.2Ni0.16Mn0.56Cr0.08O2 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% LiAlO2 coated Li1.2Ni0.16Mn0.56Cr0.08O2. The midpoint voltage value of Li1.2Ni0.2Mn0.6O2 after 100 cycles is enhanced from 2.746 V to 3.128 V with Cr doping and LiAlO2 coating. The lower Rct (charge transfer resistance) and higher DLi+ (ion diffusion coefficient) of 3 wt% LiAlO2 coated Li1.2Ni0.16Mn0.56Cr0.08O2 contribute to the excellent rate capability. The results suggest that ions doping combini...