Lithium electrochemistry of NiSe2: A new kind of storage energy material

NiSe2 thin film has been successfully fabricated by reactive pulsed laser deposition and was investigated for its electrochemistry with lithium for the first time. The reversible discharge capacities of NiSe2/Li cells cycled between 1.0 V and 3.0 V were found in the range of 314.9–467.5 mA h g−1 during the first 200 cycles. By using ex situ X-ray diffraction, transmission electron microscopy, and selected-area electron diffraction measurements, the intermediates of β-NiSe, and Ni3Se2 were identified during the reversible conversions of NiSe2 into metal nickel and Li2Se. Both cation (nickel) and anion (selenium) in NiSe2 provide the redox active centers in its electrochemical reaction with lithium, indicating one of the features of its lithium electrochemistry. The high reversible capacity and good cycle ability of NiSe2 electrode made it become a promising cathode material for future rechargeable lithium batteries.