Characteristics and current activation phenomenon of reduced graphite oxide membranes by low temperature thermal treatment for sodium ion battery electrodes

After self-assembly and thermal treatment at low temperature (350 ∘ C), reduced graphite oxide membranes (RGOM) with a specific surface area of 10.6 m 2 g[Formula: see text] and average interlayer distance of 0.372 nm were obtained. When used as free-standing electrodes for sodium ion battery (SIB), the RGOM could not show good electrochemical performances at high current density ([Formula: see text]52 mAh g[Formula: see text] at 200 mA g[Formula: see text] and [Formula: see text]22 mAh g[Formula: see text] at 500 mA g[Formula: see text]), which may be attributed to dense structure and low specific surface area. Cyclic voltammetry (CV) results showed that the energy storage of RGOM in SIB was ions’ diffusion-dependent. Thus, when the RGOM electrodes went through repeated charge/discharge cycles at 200 mA g[Formula: see text], an obvious improvement of specific capacity was found due to increase of Na[Formula: see text] diffusion speed. After [Formula: see text]300 times charge/discharge cycles, the specific capacity of RGOM was [Formula: see text]120 mAh g[Formula: see text]. Additionally, after the current activation at 200 mA g[Formula: see text], the electrodes also showed better performances at higher current density (from [Formula: see text]85 mAh g[Formula: see text] to [Formula: see text]68 mAh g[Formula: see text] at a current density of 500 mA g[Formula: see text] during 500 times charge/discharge cycles). The current activation phenomenon maybe a promising method for using RGOM as SIB electrodes on a large scale.