A presodiation strategy with high efficiency by utilizing low-price and eco-friendly Na2CO3 as the sacrificial salt towards high-performance pouch sodium-ion capacitors

Sodium-ion capacitor (SIC) bridges the gap between sodium-ion battery (SIB) and supercapacitor (SC). It can exhibit high energy density than SC and deliver high power density and cyclic property than SIB. However, the advancement of SIC is restricted by presodiation. We present a presodiation strategy with high efficiency for pouch SIC by utilizing low-price and eco-friendly Na2CO3 as the presodiation material. With a high capacity utilization (82.6%), Na2CO3 displays a specific capacity of 417.1 mAh g−1. The constructed pouch SIC with Na2CO3 as the presodiation material exhibits a superior performance: 103 Wh kg−1, 13 kW kg−1 and a capacitance retention of 84.5% after 2000 cycles.