Effect of Li1/3Mn2/3-Substitution on Electrochemical Performance of P2-Na0.74CoO2 Cathode for Sodium-ion Batteries

•The Li1/3Mn2/3-substitution Na0.74CoO2 materials are prepared by sol-gel method.•The Li1/3Mn2/3 substitution suppresses phase transformation in intercalation process.•The Li1/3Mn2/3-substitution electrode exhibits excellent rate capability.

Na0.74(Li1/3Mn2/3)xCo1-xO2 (x = 0, 1/6, 1/3, 1/2) as sodium-ion battery cathode materials are prepared by using sol-gel method. The XRD tests demonstrate that Na0.74CoO2 and its Li1/3Mn2/3-substituted samples possess typical P2 structure. The charging/discharging tests exhibit that the Na0.74CoO2 electrode has a reversible capacity of 131 mAh g−1 with good cycling performance. When Co is partially substituted by Li1/3Mn2/3, the Li1/3Mn2/3-substituted samples exhibit decreasing reversible capacity of 122, 115, 83 mAh g−1 for x = 1/6, 1/3, 1/2, respectively. However, the rate capability of the Li1/3Mn2/3-substituted samples is greatly improved due to the suppression of the complicated phase conversion in intercalation process. Moreover, the structure stability for Li1/3Mn2/3-substituted samples is apparently observed when cycled between 4.5 and 2.0 V. Therefore, the substitution of Li1/3Mn2/3 can suppress the complex phase changes of the Na-based oxides and improve their electrochemical performance, which can provide a promising choose for high-performance Na-ion storage cathode material.

Graphical abstractThe Li1/3Mn2/3-substituted Na0.74(Li1/3Mn2/3)xCo1-xO2 are prepared by by using sol-gel method. The Li1/3Mn2/3-substituted electrodes exhibit excellent rate capability (a reversible capacity of 80 mAh g−1 at 10C when x = 1/3), which results from the suppression of phase transformation in intercalation process. The Li1/3Mn2/3-substituted electrodes possibly serve as a promising high capacity, stable cathode material and excellent rate capability for sodium ion battery applications.Download high-res image (171KB)Download full-size image