P2-layered Na0.5Li0.07Mn0.61Co0.16Ni0.16O2 cathode boosted Na-storage properties via rational sub-group element doping. Issue 34 (28th June 2021) - Dai, Dongmei
Abstract : The sub-group element with low valence state and larger radius doping of a hybrid P2-layered Na0.5 Li0.07 Mn0.61 Co0.16 Ni0.16 O2 were systematically investigated. The refined XRD results and operando XRD data revealed the improved Na-storage capability. Abstract : P2-layered metal oxide cathodes exhibit great promise for use in sodium ion batteries due to their unique two-dimensional tunnel structure, high energy density and high redox potential, etc. However, the inferior structural stability and irreversible phase change of P2-layered cathodes inhibit their development. The best effective strategies to improve their structural stability and sodium storage properties are via the optimization of the P2-layered tunnel structure and morphology by adjusting the Na + contents, lithium substitution and rational element doping. Herein, the first sub-group element (Cu 2+, Ag + and Au + ) doped Na0.5 Li0.07 Mn0.61 Co0.16 Ni0.16 O2 cathodes were successfully prepared and systematically studied using operando X-ray powder diffraction (XRD), Rietveld refinement with corresponding Fourier electron cloud maps and the galvanostatic intermittent titration technique (GITT). These data indicate that the lattice parameters ( a / b, c and V ), energy barrier, and Na + diffraction coefficient of sub-group element-doped Na0.5 Li0.07 Mn0.61 Co0.16 Ni0.16 O2 cathodes are gradually improved in line with an increase in the sub-group element radii, which facilitate the kinetics of Na + migration due to the synergistic effect between the valence and radius. Additionally, the structural stability and sodium storage mechanism of the optimized hybrid Na0.5 Li0.07 Mn0.6 Co0.16 Ni0.16 Au0.01 O2 electrode was revealed via operando XRD.