Boosting the Capacitance of an Aqueous Zinc-Ion Hybrid Energy Storage Device by Using Poly(3,3′-dihydroxybenzidine)-Modified Nanoporous Carbon Cathode

Abstract

Aqueous electrochemical energy storage devices are highly safe, low cost, and environmentally benign, yet suffer from low energy storage capacity. Here, we devise a novel cathode material for making aqueous Zn-ion hybrid energy storage devices with high areal capacitance. A pseudocapacitive polymer, poly­(3,3′-dihydroxybenzidine, DHB), is electrodeposited onto the surfaces of porous active carbon (AC) granules to increase the capacitance. This composite coating has high mass loading, leading to high areal capacitance in F cm–2 scale. The flexible sandwich-structured cell made by combing the poly­(3,3′-DHB)/AC cathode and the Zn foil anode shows stable electrochemical performance upon bending. The areal capacitance of this cell is up to 1.3 F cm–2, and the maximum energy and power densities are 0.18 mWh cm–2 and 4.01 mW cm–2, respectively. Moreover, a Zn-ion micro cell is fabricated by combing two sets of carbon-paper-based finger electrodes, one is plated with Zn and the other is coated with the poly­(3,3′-DHB)/AC composite. The in-plane micro cell shows a high areal capacitance of 1.1 F cm–2 and a high areal energy density of 152 μWh cm–2. Our research suggests a new approach to make high-capacitance Zn-ion hybrid energy storage devices with different forms to meet various applications.

Electrochemical Zinc Ion Capacitors: Fundamentals, Materials, and Systems

“…Reproduced with permission. [ 118 ] Copyright 2019, American Chemical Society. h) CV, i) GCD curves, and j) charge storage mechanism of the ladder‐like polymer poly(2,3‐dithiino‐1,4‐benzoquinone) (PDB, C 6 S 2 O 2 ) n cathode.…”

“…www.advancedsciencenews.com assembled a micro ZIC using a poly(3,3′-dihydroxybenzidine, DHB) and AC composite cathode. [118] The charge storage mechanism of poly(3,3′-DHB) was elucidated to be the redox reactions of imine components (Figure 8c). In the charge state, the positively charged NH +  groups were formed, accompanying the adsorption of SO 4 2− anions (Figure 8d).…”

“…f) CV and g) GCD curves of Zn//poly(3,3′-DHB)/AC ZIC. Reproduced with permission [118]. Copyright 2019, American Chemical Society.…”

Zinc based micro‐electrochemical energy storage devices: Present status and future perspective

“…To address this stumbling issue, an effective strategy was to apply the materials with high pseudocapacitance into the cathode. For instance, Wang et al 102 devised an innovative cathode of a pseudocapacitance polymer (poly(3,3′‐dihydroxybenzidine) [DHB]) electrodeposited onto the surfaces of porous active carbon and zinc anode by electrodeposition (Figure 6B). Assisted with the pseudocapacitance polymer, the resulting ZIMSCs exhibited ultrahigh areal capacitance of 1.1 F/cm 2 and maximum areal energy density of 152 μWh/cm 2 , in conjunction with high capacity retention of 80% after 3000 cycles.…”

“…B, Schematics of ZIMSCs based on DHB and zinc anode, corresponding SEM images. Reproduced with permission 102 . Copyright 2019, American Chemical Society.…”