Unlocking the electrochemistry abilities of nanoscaled Na 2/3 Ni 1/4 Mn 3/4 O 2 thin films

Different thickness of Na2/3Ni1/4Mn3/4O2 thin films were deposited on stainless steel substrates by pulsed laser deposition technique. X-ray diffraction and field-emission scanning electron microscope results reveal that the thin film with highly preferred c-axis orientation is composed of homogeneous nano-sized grains. The charge/discharge tests indicate that the 0.55 μm thick film demonstrates a high initial discharge capacity of 175.3 mAhg−1 and a retention of 91% after 30 cycles at a current density of 13 mAg−1. Furthermore, as the current density increases from 13 to 130 mAg−1, about 89% of its initial discharge capacity can be maintained, exhibiting excellent rate capability. These superior electrochemical properties would promote Na2/3Ni1/4Mn3/4O2 thin film to be a promising cathode material for sodium-ion micro-batteries.