Abstract
Reduced graphene oxide (rGO) sheets were synthesized by a modified Hummer's method without additional reducing procedures, such as chemical and thermal treatment, by appropriate drying of graphite oxide under ambient atmosphere. The use of a moderate drying temperature (250°C) led to mesoporous characteristics with enhanced electrochemical activity, as confirmed by electron microscopy and N2 adsorption studies. The dimensions of the sheets ranged from nanometres to micrometres and these sheets were entangled with each other. These morphological features of rGO tend to facilitate the movement of guest ions larger than Li+. Impressive electrochemical properties were achieved with the rGO electrodes using various charge-transfer ions, such as Li+, Na+ and K+, along with high porosity. Notably, the feasibility of this system as the carbonaceous anode material for sodium battery systems is demonstrated. Furthermore, the results also suggest that the high-rate capability of the present rGO electrode can pave the way for improving the full cell characteristics, especially for preventing the potential drop in sodium-ion batteries and potassium-ion batteries, which are expected to replace the lithium-ion battery system
Highlights
Over the past decades, various carbonaceous graphite species, such as natural graphite, coke and graphitized carbon have been widely investigated as the anodes for rechargeable lithium-ion batteries (LIBs)
The TEM image of the sample prepared at 2508C in figure 1f details the morphology and porous features of the Reduced graphene oxide (rGO)
The rGO samples synthesized by this simple method are activated to different degrees with increasing drying temperature
Summary
Various carbonaceous graphite species, such as natural graphite, coke and graphitized carbon have been widely investigated as the anodes for rechargeable lithium-ion batteries (LIBs). Among the different types of carbon anodes, natural graphite appears to be the most promising candidate due to its high capacity, low cost and low electrode potential relative to lithium metal [1]. LIBs do not meet the performance criteria (including cost, charge/discharge rate, energy density and safety) needed to enter new markets such as those for all-electric vehicles and for the storage of electrical energy from renewable wind and/or solar plants [2]. In this respect, researchers have explored rechargeable battery systems with alternative charge carriers. Sodium-ion and potassium-ion batteries offer attractive features of low cost, lower toxicity, improved safety and the ability to use electrolytes with low decomposition potential [3]
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