Optimization of Sr-doping boosting the structural stability for single crystalline LiNi0.8Co0.1Mn0.1O2 cathode to enhance its electrochemical performance at elevated voltage and temperature

Abstract

Single crystalline (SC) Ni-rich cathodes have been considered the potential cathodes for the next generation lithium-ion batteries. Unfortunately, some inevitable defects, such as severe irreversible phase transition, microcracks formation and transition metal dissolution at high voltage, hinder its commercial applications. Herein, a high stable modified SC-LiNi0.8Co0.1Mn0.1O2 cathode is prepared by using Sr doping strategy, which is helpful to tackle the above challenges simultaneously. The introduction of Sr atoms can occupy the transition metal sites of the material, resulting in the increase of Li/Ni exchange energy and the improvement of oxygen layer stability. Meanwhile, Sr doping can promote the growth of primary particles and reduce the agglomeration of SC particles. The optimized doped sample of 0.5Sr-NCM exhibits pronounced improvements in pouch-type full cell with a remarkable capacity retention of 86.6% after 1200 cycles at 1C between 2.8 and 4.35 V (45 °C), while the pristine sample only shows a capacity retention of 80.8% after 798 cycles. The mechanism of enhanced electrochemical properties for the doped sample is revealed by the characterization analyses and density functional theory calculation. This work provides a facile strategy to regulate the bulk structure of SC Ni-rich materials, which may promote the development of high-energy-density lithium-ion batteries.