In-situ catalytic dehydration construction of hierarchical nano microporous carbon with NH4Cl for supercapacitors and zinc ion hybrid capacitors

Hierarchical porous carbon is an ideal electrode material in the electrochemical energy storage, but the relatively single distribution of micropores has poor universality for different electrolytes, especially for the electrolytes with large ion sizes. Herein, a simple strategy for enhancing the electrochemical performance of biomass-based porous carbon by constructing hierarchical nano micropores is developed, using NH 4 Cl as in-situ catalytic dehydration agent of high molecular polysaccharide polymer, and ZnCl 2 as synergistic dehydration activator. The hierarchical nano micropores greatly improves the capacitance, rate performance, and electrochemical stability of corn straw-derived porous carbon in KOH, Na 2 SO 4 and ZnSO 4 electrolytes. In 1 M Na 2 SO 4 system with large-sized ion, the specific capacitance of CSPC-N-850 electrode can increase from 124.4 to 260.4 F g −1 , the rate performance increase from 63.8 % to 80.4 %, and without capacity degradation in ultra-high current density of 10 A g −1 after 100,000 charge/discharge cycles. In addition, CSPC-N-850 electrode also exhibits excellent electrochemical performances in zinc ion hybrid capacitor with a high specific capacity of 135.7 mAh g −1 at 0.2 A g −1 , good energy density of 99.6 Wh kg −1 at the power density of 412.1 W kg −1 , and 100 % of capacitance retention after 5000 cycles at 1 A g −1 .