LiNi_0.5Mn_1.5O₄ Cathode Materials Co-Doped with La³⁺ and S²⁻ for Use in Lithium-Ion Batteries (Supporting Information)

Spherical LiNi_0.5Mn_1.5O₄ particles co-doped with lanthanum (La) and sulfur (S) were synthesized by a facile co-precipitation assisted solid-state annealing method with stable oxysulfide La₂O₂S (x = 0, 0.3, 0.5, 0.7, 1.0, and 1.2 at%) as a dopant. The prepared composite materials exhibited a slight shrinkage of lattice parameters without any impurity phase under x ≤ 0.7 at%, and the Ni/Mn disordered arrangement in the spinel lattice increased with an increase in the ratio of dopants, as confirmed by X-ray diffraction and Raman spectroscopy. X-ray photoelectron spectroscopy and electrochemical measurements also clearly indicated that the residual Mn³⁺ in the cubic lattice could be effectively eliminated with the use of La₂O₂S dopants. The composite materials showed outstanding rate and cycling performance compared with those of the pristine material. Specifically, the material doped with 0.5 at% La₂O₂S showed a high reversible capacity of 115.9 mAh g⁻¹ at 10 C, and a remarkable cycling performance of 109.2 mAh g⁻¹ even after 200 cycles. All of these extraordinary performances were attributed to the synergistic effects of La and S in the spinel structure, which induce a suitable pathway for lithium ion and a robust architecture during the electrochemical assessment.