Fabrication of 2D NiO Porous Nanosheets with Superior Lithium Storage Performance via a Facile Thermal-Decomposition Method

Because of their good mechanical flexibility and large exposed surfaces, two-dimensional (2D) nanostructures have attracted tremendous attention in the fields of renewable energy storage and conversion devices. However, fabricating 2D nanostructures with a facile and low-cost route remains a big challenge. In this work, a very facile thermal-decomposition strategy is proposed for preparing 2D NiO porous nanosheets by using nickel chloride and glucose as raw materials. In contrast to the microsized NiO polyhedrons, the 2D NiO porous nanosheets show significantly improved lithium storage capability. Benefiting from the robust 2D framework and porous nanostructure, the 2D NiO porous nanosheets exhibit high reversible capacity (926.5 mA h g–1 after 500 cycles at 1 A g–1), long cycling stability (557.7 mA h g–1 after 1100 cycles at 3 A g–1), and high-rate capability (350.7 mA h g–1 at 10 A g–1). The lithium storage mechanism of the 2D NiO porous nanosheets is explored based on ex situ X-ray diffraction, fourier transformation infrared spectrometry, transmission electron microscopy, and X-ray photoelectron spectroscopy measurements, combined with cyclic voltammetry and electrochemical impedance spectroscopy measurements. It reveals that the capacitive-controlled lithium storage originating from the reversible formation/dissolution of polymer/gel-like layer gives a remarkable contribution to the overall capacity of the 2D NiO porous nanosheets, which leads to the outstanding lithium storage performance. The 2D NiO porous nanosheets also show a good cycling performance when used as an anode material for full-cell lithium-ion battery (NiO//LiCoO2). The reported facile and low-cost method provides an avenue for the design and massive production of 2D nanostructured electrode materials for high performance lithium-ion batteries.