Single-Crystalline Ni-Rich layered cathodes with Super-Stable cycling

Robust single-crystalline Ni-rich cathodes with increasing Ni proportion, LiNi0.83Co0.11Mn0.06O2 (SC83), LiNi0.88Co0.06Mn0.06O2 (SC88), and LiNi0.95Co0.03Mn0.02O2 (SC95) were successfully designed with molten salt-assisted method, and the correlation between the Li+ storage properties, particle microcracking, surface phase transitions, and Ni fraction in the single-crystalline Ni-rich cathodes have been profoundly investigated. [Display omitted] •-crystalline Ni-rich cathodes with increasing Ni proportion were designed with molten salt-assisted method.•The single-crystalline LiNi0.83Co0.11Mn0.06O2 cathode presents superior structural stability and cycling durability.•Performance degradations were attributed to the aggravated Li/Ni mixing and H2 ↔ H3 phase transition.•It provides approach for designing high-energy density and stable single-crystalline Ni-rich cathodes. Further commercial development of polycrystalline Ni-rich layered cathode is severely hindered by the deep-rooted particle microcracking, mainly initiated among the randomly orientated grain boundaries of the primary particles. Herein, robust single-crystalline Ni-rich LiNi0.83Co0.11Mn0.06O2 (SC83) prepared by molten salt-assisted method shows the enhanced structure stability and cycling durability. It’s found that the particle microcracking is effectively removed for SC83 cathode during prolonged cycling helped with its eliminated grain boundaries and slight crystal shrinkage, leading to superior capacity retention of 92.8% after 100 cycles. Notably, the discharge capacity and energy density are effectively boosted with increasing Ni fraction majorly based on the more available Ni2+/Ni3+ redox, giving rise to high capacities of 211.2 and 219.4 mAh g−1 for LiNi0.88Co0.06Mn0.06O2 (SC88) and LiNi0.95Co0.03Mn0.02O2 (SC95) cathodes, respectively. However, the particle microcracking is progressively exacerbated owing to the aggravated Li/Ni mixing and H2 ↔ H3 phase transition with Ni proportion higher than or equal to 88% in SC cathodes, resulting in severe structure collapse and capacity fading during high-rate cycling, in which a poor capacity retention of 51.8% after 250 cycles at 5C is observed for single-crystalline SC95cathode. This work sheds light on the rational design of single-crystalline Ni-rich cathodes, and highlighted the trade-off between the energy density and cycling durability, facilitating the extensive applications of single-crystalline Ni-rich cathodes in high-performance ele