Sewable and Cuttable Flexible Zinc-Ion Hybrid Supercapacitor Using a Polydopamine/Carbon Cloth-Based Cathode

The booming of portable electronics has stimulated great interest in developing flexible Zn-ion hybrid supercapacitors (Zn HSCs) that feature low cost and high operational safety. However, the commercial applications of Zn HSCs are greatly hindered by low energy density due to the low capacity of the cathode and also the invalid weight of the flexible current collector. Here, a free-standing cathode is developed by patterning redox-active polydopamine (PDA) with abundant quinone groups on the porous carbon cloth substrate via a hydrothermal polymerization process. Unlike the traditional carbon cloth-based electrode, the carbon cloth adopted here is activated by the air calcination process, which is beneficial for the loading of PDA and absorption of Zn2+ ions. Benefiting from the hybrid mechanism of Zn2+–quinone group coordination and electrical double layer absorption, the polydopamine-coated porous carbon cloth (PDA@PCC) delivers a high area capacity of 1.25 mA h cm–2 and a high capacity retention of 100% after 10,000 cycles at a current density of 10 mA cm–2. Moreover, when assembled into flexible Zn HSCs, PDA@PCC still displays a high capacity of 0.92 mA h cm–2, and the flexibility and operation safety have also been demonstrated by several extreme condition tests, such as cutting and sewing tests. This work may promote new opportunities for next-generation flexible Zn HSCs.