A novel boron-doping approach for long-term cycling life of Li-rich layered cathode

Abstract

The commercial application of Li-rich Mn-based layered oxides (LLOs) is hindered due to their instability of lattice oxygen and dissolution of manganese. Herein, an effective and large-scale production co-precipitation boron-doping strategy was proposed to improve the performance of Li1.15Mn0.53Ni0.22Co0.1O2. We found that the boron introduced in the co-precipitation process will be uniformly distributed in the bulk and the resulting boron-doped Li1.15Mn0.53Ni0.22Co0.1O2 shows excellent electrochemical properties with low doping amount. Multi-dimensional analysis shows that boron doping significantly improves the structural stability of materials. After 1200 cycles at 1C, boron-doped sample can deliver 147 mAhg−1 with an excellent retention of 80.1%, which is much higher than that of the pristine sample of 44% after 700 cycles. Moreover, the discharge voltage decay of the boron-doped samples is only 0.54 mV per cycle (1.39 mV for pristine). It is worth mentioning that the pouch-cell full battery cycle performance of doped samples is also excellent. The doped cathode//graphite shows a superior capacity retention of 83.6% after 500 cycles without gas generation, while the pristine//graphite only hold the 46.6% of initial capacity. The dQ/dV curves and the SEM/EDS of electrode analysis verified higher reversibility of lattice oxygen, less manganese dissolution and more stable microstructure, which greatly improved the cycling life after boron doping.