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 article 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 N-doped carbon (As8Mg) electrode achieved a reversible capacity of 254 mA h g⁻¹ at 0.1 A g⁻¹. Moreover, the As8Mg-based SIC device achieves high combinations of power/energy densities (53 W kg⁻¹ at 224 Wh kg⁻¹ and 10 410 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 pseudocapacitive mode.