Zirconium effect on the lithiation mechanism of LiNi_0.83Mn_0.05Co_0.12O₂ positive electrode material

Ni-rich LiNi_1-x-yMn_xCo_yO₂ (x + y ≤ 0.2) materials are employed to enhance the energy density of lithium-ion batteries, while they are still facing the stability issue. Doping is considered as an efficient approach to improve the stability of the LiNi_1-x-yMn_xCo_yO₂ materials. A considerable number of studies have concluded that Zr-doping improves the stability when undoped and doped LiNi_1-x-yMn_xCo_yO₂ materials are lithiated under the same conditions. Unfortunately, a fundamental understanding of the Zr dopants role during lithiation conditions is still lacking. This work investigates the Zr effects on lithiation mechanism of LiNi_0.83Mn_0.05Co_0.12O₂ (NMC). The main findings are: First, the NMC and Zr-doped NMC have different lattice parameter growth speeds, and the (003) & (101) lattice planes form order structures at lower temperatures during lithiation process when the dopant is included. Second, Zr is prone to locate near the surface region of NMC secondary particles. Third, when lithiation time increases from 8 h to 12 h at 800 °C, the undoped NMC electrochemical performance deteriorates whereas the doped material improves. These findings highlight that understanding the mechanism behind lithiation conditions is essential for doped LiNi_1-x-yMn_xCo_yO₂. The insights revealed in this work can guide for design of other dopants for Ni-rich positive electrode materials.