S‐doped 3D porous carbons derived from potassium thioacetate activation strategy for zinc‐ion hybrid supercapacitor applications

Aqueous zinc-ion hybrid supercapacitors (ZHSCs) emerge as a promising option for green energy storage in recent years. However, development of reliable carbon-based cathodes remains a challenge. Herein, an effective potassium thioacetate activation technique has been promoted for the producing of S-doped 3D porous carbons (S-3DPCs) by employing sustainable pine needles as the carbon source without any additives. Different from the previously reported routes, the potassium thioacetate can serve as the activator as well as the S source. The resulting S-3DPCs display a unique 3D architecture with a large specific surface area, a certain amount of sulfur (~0.88-3.60 at%), which enables S-3DPCs to exhibit excellent electrochemical performance as the cathodes for ZHSCs. Particularly, S-3DPC-800 (pyrolysis at 800) can deliver a large specific capacity of 203.3 mAh g−1 (the volumetric capacity is 123.8 mAh cm−3) in 2 M ZnSO4 at 0.2 A g−1, high rate performance, and outstanding cyclic durability. Moreover, S-3DPC-800-based ZHSCs can possess the maximum energy density up to 162.6 Wh kg−1 (99.0 Wh L−1) at a power density of 160 W kg−1 (97.4 W L−1), which suggests the significant potential of S-3DPCs as the robust cathodes for ZHSCs. This facile potassium thioacetate activation strategy points toward a new way to develop S-doped 3D porous carbon cathodes for high performances ZHSCs applications.