Self-Catalysis-Graphitization Strategy Toward Coal-Derived Graphitic Hierarchical Porous Carbon with Advanced Zn-Ion...

Based on dual carbon targets, it is a clean and efficient utilization to convert coal into high value-added carbon materials for Zn-ion hybrid supercapacitor (ZIHSC), coupling high energy density of batteries and high power output of supercapacitors. Herein, a one-step self-catalysis-graphitization approach is developed to fabricate N/O/S co-doped graphitic hierarchical porous carbon from bituminous coal by taking advantages of the intrinsic heteroatoms for self-doping, the associated minerals for graphization and KOH activation for hierarchical porosity, contributing to abundant entrapments for Zn²⁺ capture, express transfer pathway for fast kinetics and sturdy skeleton for long-term duration and thereby endowing the coin-type ZIHSC device an ultrahigh capacity of 229.8 mAh g^-1 at 0.1 A g^-1 with 110.7 mAh g^-1 conservation even at a 500-fold amplified current density, the maximum energy density of 183.2 Wh kg^-1 and an outstanding stability of 99.3% over 100,000 cycles at 50 A g^-1. Gratifyingly, the soft-pack ZIHSC device still delivered a capacity of 141.2 mAh g^-1 at 0.1 A g^-1 and a energy density of 112.3 Wh kg^-1 for practicability. The quasi-solid ZIHSC device also displayed a capacity of 144.7 mAh g^-1 at 0.1 A g^-1 with a energy density of 115.2 Wh kg^-1 plus excellent mechanical flexibility.