Structural stabilizing action of terbium cation and phosphate anion to layered transition-metal oxide cathodes

Abstract

The capacity decay and safety issues of layered cathodes caused by structural deterioration upon deeply delithiated state, have impeded the further large-scale commercial-used of layered transition-metal cathodes in advanced lithium-ion batteries. In this work, the terbium cation and phosphate anion are doped homogeneously into LiCoO2 and LiNi0.83Co0.11Mn0.06O2 cathodes via the facile solid phase reaction method. We found that the lattice oxygen can be stabilized by the introduction of the Tb element, leading to the mitigation of structural degradation. More impressively, the PO43− polyanion possesses a benign binding affinity for Li-ions, further accelerating Li-ion transportation. Theoretically, the incorporation of the Tb element into the crystal lattice can alleviate oxygen redox activity in the high delithiation state. Thus, the introduction of an appropriate content of anion and cation dopants synergistically modulates the robust layered structure to suppress structural collapse during cycling. Consequently, the Tb element and PO43− polyanion co-doped LiNi0.83Co0.11Mn0.06O2 (a capacity of 179.3 mAh g−1 after 100 cycles with capacity retention of 96%) and LiCoO2 (169.4 mAh g−1 after 400 cycles and with capacity retention of 95%) illustrate prominent cycling stability. This study proposes a feasible and powerful strategy for enhancing the structural stability and cycling durability of high-voltage LiCoO2 and nickel-rich ternary layered cathode materials.