Preparation of M1/3Ni1/3Mn2/3O2 (M = Mg or Zn) and its performance as the cathode material of aqueous divalent cations battery.

M 1/3 Ni 1/3 Mn 2/3 O 2 (M = Mg or Zn) is sucessfully synthesize from Na 2/3 Ni 1/3 Mn 2/3 O 2 via a electrochemical conversion method. The structure and morphology of the as-prepared material are systematically characterized by X-ray diffraction (XRD), scanning electron microscopy (SEM), transmission electron microscopy (TEM), inductively coupled plasma atomic emission spectroscopy (ICP-AES) and X-ray photoelectron spectroscopy (XPS), respectively. The nano-sized morphology of M 1/3 Ni 1/3 Mn 2/3 O 2 is beneficial for the reduction of diffusion length and transfer acceleration of cations from the surface into the bulk interiors. XRD patterns reveal that crystal structure is maintained after the reversible Mg 2+ or Zn 2+ intercalation/deintercalation. Its performance for Mg 2+ and Zn 2+ intercalation/deintercalation in aquesous electrolytes is evaluated by cyclic voltammetry, galvanostatic cycling and electrochemical impedance spectroscopy. Mg 1/3 Ni 1/3 Mn 2/3 O 2 exhibits an initial capacity of 170.5 mAh g −1 in 1 mol L −1 Mg(NO 3 ) 2 , Zn 1/3 Ni 1/3 Mn 2/3 O 2 displays capacity of 113.7 mAh g −1 in 1 mol L −1 ZnSO 4 . Mg 1/3 Ni 1/3 Mn 2/3 O 2 shows a good cycling performance and maintains 52.7 mAh g −1 at 1.0C after 200 cycles in 1.0 mol L −1 MgSO 4 . [ABSTRACT FROM AUTHOR]