Sodium-ion batteries (SIBs) are now emerging as a low-cost alternative to the current lithium-ion batteries, but their performance is limited by the sluggish transportation of large Na ions in electrodes. Expanded graphite has been employed in enhancing the transport kinetics. However, high-performance graphite should be synthesized at high temperatures when using traditional methods, which inevitably increases the total cost of material production. To tackle the kinetic issue for SIBs, we develop a three-dimensional network of graphene during catalytic graphitization in carbon electrodes at a temperature as low as 450 °C by using Prussian blue as a precursor. Furthermore, a strategy is proposed to enhance the transport ability of the Na-ion in the network by controlling the diffusion distance of the Fe cluster and the distance between Prussian blue particles, leading to optimized performance with both excellent high-rate performance (167 mAh g-1 at 1.0 A g-1) and high charging capacity (390 mAh g-1 at 0.05 A g-1). The results provide insights into the engineering of ionic transport properties through low-temperature catalytic graphitization in electrodes for SIBs and help design high-performance and low-cost electrodes for large-scale energy storage systems.
Keywords: Prussian blue; catalytic graphitization; graphene; ionic transport; sodium-ion battery.