Trace doping realizing superior electrochemical performance in P2-type Na0.50Li0.08Mn0.60Co0.16Ni0.16O2 cathode for sodium-ion batteries

P2-type layered oxides are receiving significant interest due to their superior structure and intrinsic performances. There are strenuous attempts to balance the structure stability, phase transition as well as desirable electrochemical performances by inducing anion/cation ions, changing morphology, adjusting valence, etc. In this work, several same-period elements of Sc, Ti, V, Cr, Fe, Cu and Zn are doped into Na0.50Li0.08Mn0.60Co0.16Ni0.16O2 cathodes, which are manipulated by ions radii and valence state, further studied by operando X-ray powder diffraction patterns (XRD). As a result, the Cu2+ doped cathode performed higher rate capacities (as high as 86 mAh/g even at 10 C) and more stable structures (capacity retention of ∼89.4% for 100 cycles), which owing to the synergistic effect among the tightened TMO2 layer, enlarged d-spacing, reduce O-O electrostatic repulsion, ameliorate lattice distortion as well as mitigate ordering of Na+/vacancy.