Improving the electrochemical performances of Li rich Li1.20Ni0.13Co0.13Mn0.54O2 through a cooperative doping of Na and PO43 with Na3PO4

Li rich layered oxide cathodes suffer from poor rate capability, voltage decay and inferior cycling stability. Herein, we propose a novel synergistic strategy to improve the electrochemical performances of Li rich Li1.20Ni0.13Co0.13Mn0.54O2 by the co doping of Na and PO4 3 amp; 8722;. The co doping of Na for Li and PO4 3 amp; 8722; for Mn is simultaneously achieved using Na3PO4 as a dopant. The co doping of Na and PO4 3 amp; 8722; not only enhances the high rate performance 106.4 mAhg amp; 8722;1 10C and capacity retention 93.8 1C 100 cycles but also mitigates the voltage decay owing to the synergistic effect of Na and PO4 3 amp; 8722; co doping. The synergistic mechanism is unraveled based on neutron diffraction, aberration corrected scanning transmission electron microscope, Xray photoelectron spectroscopy, ex situ X ray absorption spectra, ex situ X ray diffraction, electrochemical impedance spectroscopy and electrochemical measurements. The co doping of Na and PO4 3 amp; 8722; enlarges the interlayer spacing and suppresses Li Ni mixing which increases Li diffusivity and enhances the rate capability. Meanwhile, the co doping of Na and PO4 3 amp; 8722; shrinks the thickness of the slabs, weakens the TM O covalency and alleviates the volume change in the charge discharge process which improves the layered structure stability and the cycling performances. This study presents some new insights into designing high performance cathode materials through a cooperative modulation of different crystal sites dopin