Template-induced graphitic nanodomains in nitrogen-doped carbons enable high-performance sodium-ion capacitors

Sodium-ion capacitors (SICs) have great potential in energy storage due to their low cost, the abundance of Na, and the potential to deliver high energy and power simultaneously. This paper demonstrates a template-assisted method to induce graphitic nanodomains and micro-mesopores into nitrogen-doped carbons. This study elucidates that these graphitic nanodomains are beneficial for Na+ storage. The obtained As8Mg electrode achieved a reversible capacity of 254 mA h g−1 at 0.1 A g−1 and excellent cycling stability of 98.7% capacity retention over 350 cycles. Moreover, the As8Mg-based SIC device achieves high combinations of power/energy densities (52 W kg−1 at 204 Wh kg−1 and 10,456 W kg−1 at 51 Wh kg−1) with outstanding cycle stability (99.7% retention over 600 cycles at 0.2 A g−1). Our findings provide insights into optimizing carbon’s microstructure to boost sodium storage in the pseudo-capacitive mode.