Hydroquinone versus Pyrocatechol Pendants Twisted Conjugated Polymer Cathodes for High‐Performance and Robust Aqueous Zinc‐Ion Batteries

Abstract

Aqueous zinc-ion batteries (ZIBs) have emerged as a cost-effective and safe energy storage technology but have remained a challenge in developing efficient Zn 2+ hosting materials for large-scale applications. The authors have herein designed a ladder-type dithieno[3,2-b:2′,3′-d]pyrrole core twisting hydroquinone or pyrocatechol redox pendants as redox conducting polymer cathodes for highly-efficient and robust aqueous ZIBs. The impact of pendant configuration on the energy level, Zn 2+ hosting behavior, and battery performance of these polymer electrodes are systematically investigated. Experimental and theoretical studies clearly reveal the outstanding molecular planarity and highly reversible redox reaction for hydroquinone-derived PDpBQ cathode, which can effectively tackle the bottleneck problems for ZIBs on aspects of structural stability and Zn 2+ insertion/extraction dynamics. Steady capacity output upon 120 mAh g −1 is achieved with considerable rate performance (52.5% of capacity retention at 5 A g −1 ), while pyrocatechol-derived polymer PDoBQ exhibits a sharply fading redox responsiveness (over 45%) due to restricted charge transfer and unselective zinc-ion capturing nature. This molecular design of highly conductive backbone twisting redox pendants with planar molecular plane and specific Zn 2+ hosting as polymer cathodes demonstrates an effective strategy for high-performance and robust ZIBs.

A quinoxalinophenazinedione covalent triazine framework for boosted high-performance aqueous zinc-ion batteries

“…14,15 Among them, aqueous zinc-ion batteries (AZIBs) have shown great potential as candidate rechargeable batteries for nextgeneration grid-scale energy storage, mainly attributed to their nonammability, low cost and environmental benignity. 16,17 Compared to other metal anodes for aqueous batteries, the zinc anode possesses high theoretical capacity (820 mA h g À1 ) and low redox potential (À0.76 V vs. SHE). The search for suitable cathode materials, however, remains urgent since they determine the energy density and cycling performance of AZIBs.…”

Manipulating Polymer Configuration to Accelerate Cation Intercalation Kinetics for High‐Performance Aqueous Zinc‐Ion Batteries

“…More importantly, the initial capacity remains 97% when current density is switched back to 0.3 A g -1 . Overall, P3Q-t displays superior electrochemical performance comparable to those of the state-of-the-art organic ZIB cathodes based on redox polymers (Figure 3d;Table S1, Supporting Information), [12,23,36,[44][45][46][47][48], e.g., PDBS (260 mA h g -1 at 0.1 A g -1 ), [12] t-CNTs-PA-PE (238 mA h g -1 at 0.2 A g -1 ), [44] PDA (126 mA h g -1 at 0.02 A g -1 ), [45] HqTp-COF (276 mA h g -1 at 0.125 A g -1 ), [46] Cu 3 (HHTP) 2 (228 mA h g -1 at 0.05 A g -1 ). [48] We further conducted the long-term GCD cycles for polymerbased ZIBs at the current density of 3 A g -1 (Figure 3e).…”

“…The b-value obtained by fitting logarithmic equation: log(i) = log(a) + blog(v), is used to distinguish the charge storage kinetics of electrode materials. [23] For redox polymer in aqueous electrolytes, the intercalation and migration of hydrated ions occur within active site layer (ca. CO, CN, etc.)…”

“…[20,21] However, Zn 2+ ions reveal not only a high energy barrier that retards solid state diffusions but sluggish interfacial charge transfer due to strong solvation and ion-pair formation. [22,23] Moreover, it usually motivates the inevitable compensation of hydrion (H + ) to participate in redox reactions (generally seen in acidic aqueous zinc electrolyte such as ZnSO 4 ), which may aggravate poor rate and cycle performance caused by impeded Zn 2+ transfer. [24,25] Up to now, there have been many studies about organic cathodes for exploring their charge storage mechanisms in ZIBs (including Zn 2+ , H + , and Zn 2+ /H + co-insertion).…”

Conducting polymers with redox active pendant groups: their application progress as organic electrode materials for rechargeable batteries

“…169 Previous studies have demonstrated that faster electron transport pathways can be provided by the grafting of quinone groups to long conjugated polymer chains. 167,170 Wang et al 171 were inspired to graft twisting para-benzoquinone (pBQ) to the ladder-type dithieno[3,2-b : 2 0 3 0 -d]pyrrole core as the redox conducting polymer of ZIB cathodes. The hydroxyl group of quinone groups was oxidized to form oxygen radicals, providing a large number of active sites that bind only to Zn 2+ , and showing highly reversible Zn 2+ insertion/release during the charge and discharge of the battery.…”