Morphology and Lattice Regulation Stabilizes High-Voltage Single-Crystal Ni-Rich Cathodes

Single-crystal Ni-rich cathodes possess prominent structural integrity and thermal stability compared to the poly-crystal counterparts, yet their application at high-voltage is hampered by the intragranular cracks which remain intractable to be availably mitigated. Herein, an efficacious morphology and lattice regulation is achieved in single-crystal LiNi0.83Co0.12Mn0.05O2 (NCM) by in-situ Nb5+ doping. Doped Nb5+ reduces the surface energies of (001), (012), and (104) faces, following by the diminution of grain size based on the classical nucleation theory. Less planar slips exist in Nb5+ doped single-crystal cathodes than the pristine under the voltage of 4.8 V, accompanied by scare intragranular cracks after 100 cycles. Meanwhile, a heterogeneous structure can be constructed by Nb5+ doping on the grain surface, which acts as a shield to alleviate deleterious interfacial phase transition. Under a high-voltage of 4.4 V, the 0.5 mol% Nb5+ doped NCM delivers an outstanding discharge capacity (211.3 mAh g-1) at 0.1C, a higher capacity retention (155.0 mAh g-1 vs. 130.2 mAh g-1) at 1C after 100 cycles and a superior rate capacity (152.3 mAh g-1 vs. 118.9 mAh g-1) at 5C in comparison with the pristine. This bifunctional regulation strategy provides a novel insight for the rational design of single-crystal Ni-rich cathodes.