Improving Li⁺ Kinetics and Structural Stability of Nickel-Rich Layered Cathodes by Heterogeneous Inactive-Al³⁺ Doping

To improve the Li⁺ kinetics and structural stability of high-capacity nickel-rich layered oxides, but not at the cost of reducing reversible capacity, a heterogeneous inactive-Al³⁺ doping strategy is proposed to build an Al³⁺-rich surface within a low doping amount. As anticipated, the heterogeneous inactive-Al³⁺ doped nickel-rich LiNi_0.7Co_0.15Mn_0.15O₂ shows a large reversible capacity of ∼215 mAh g^–1, corresponding to a high energy density of ∼850 Wh kg^–1. Moreover, it also exhibits long-term cycle lifespan, capacity retention of ∼90% after 200 cycles even at a high upper cutoff voltage of 4.5 V (vs Li/Li⁺), and improved thermal stability. Surprisingly, the heterogeneous inactive-Al³⁺ doped electrode shows a high capacity of ∼145 mAh g^–1 even at a high rate of 10C, which corresponds to ∼70% capacity retention at 0.1C, due to the enhanced Li⁺ kinetics. Also this heterogeneous inactive-ion doped approach is capable of being readily expanded to other types of layered, spinel and olivine cathodes to enhance their structural stability and Li⁺ kinetics