Crack-free single-crystalline Co-free Ni-rich LiNi0.95Mn0.05O2 layered cathode

The rapid growth in global electric vehicles (EVs) sales has promoted the development of Co-free, Ni-rich layered cathodes for state-of-the-art high energy-density, inexpensive lithium-ion batteries (LIBs). However, progress in their commercial use has been seriously hampered by exasperating performance deterioration and safety concerns. Herein, a robust single-crystalline, Co-free, Ni-rich LiNi0.95Mn0.05O2 (SC-NM95) cathode is successfully designed using a molten salt-assisted method, and it exhibits better structural stability and cycling durability than those of polycrystalline LiNi0.95Mn0.05O2 (PC-NM95). Notably, the SC-NM95 cathode achieves a high discharge capacity of 218.2 mAh g(-1), together with a high energy density of 837.3 Wh kg(-1) at 0.1 C, mainly due to abundant Ni2+/Ni3+ redox. It also presents an outstanding capacity retention (84.4%) after 200 cycles at 1 C, because its integrated single-crystalline structure effectively inhibits particle microcracking and surface phase transformation. In contrast, the PC-NM95 cathode suffers from rapid capacity fading owing to the nucleation and propagation of intergranular microcracking during cycling, facilitating aggravated parasitic reactions and rock-salt phase accumulation. This work provides a fundamental strategy for designing high-performance single-crystalline, Co-free, Ni-rich cathode materials and also represents an important breakthrough in developing high-safe, low-cost, and high-energy LIBs.

Automated summary

This study successfully designed a robust single-crystalline, Co-free, Ni-rich cathode material, which has advantages over polycrystalline materials in terms of structural stability and cycling durability and can achieve high discharge capacity and high energy density, with good capacity retention.