Orthoquinone–Based Covalent Organic Frameworks with Ordered Channel Structures for Ultrahigh Performance Aqueous Zinc–Organic Batteries

Abstract

Elaborate molecular design on cathodes is of great importance for rechargeable aqueous zinc-organic batteries' performance elevation. Herein, we design a novel orthoquinone-based covalent organic framework with an ordered channel structures (BT-PTO COF) cathode for an ultrahigh performance aqueous zinc-organic battery. The ordered channel structure facilitates ions transfer and makes the COF follow a redox pseudocapacitance mechanism. Thus, it delivers a high reversible capacity of 225 mAh g À 1 at 0.1 A g À 1 and an exceptional long-term cyclability (retention rate 98.0 % at 5 A g À 1 ( � 18 C) after 10 000 cycles). Moreover, a co-insertion mechanism with Zn 2 + first followed by two H + is uncovered for the first time. Significantly, this co-insertion behaviour evolves to more H + insertion routes at high current density and gives the COF ultra-fast kinetics thus it achieves unprecedented specific power of 184 kW kg À 1 (COF) and a high energy density of 92.4 Wh kg À 1 (COF) . Our work reports a superior organic material for zinc batteries and provides a design idea for future high-performance organic cathodes.

Proton storage chemistry in aqueous zinc‐organic batteries: A review

“…Thus, as illustrated in Figure 11C, the organic electrode materials located in region A are usually some small molecules with loose π-π interaction, which exhibit a limited cyclic life. As a contrast, the COFs 69,75,87 and some molecules with enlarged conjugated planes supramolecular structure (such as HATNQ 62 ) located in region B, demonstrate redox electrochemistry dominated by Zn 2+ intercalation (as discussed above) and show robust cycling stability. Consequently, although the storage of proton will improve the utilization rate of active groups in organic electrode materials and the capacity of aqueous Zn-organic batteries, especially in at large current density, the effect of proton storage on cycling stability deserves careful consideration.…”

“…The evolution of proton storage chemistry. 58,61,[67][68][69] storage was dominant in Zn-HATN batteries, which may originate from the proton-chelating ability of imine groups in the π-conjugated aromatic compounds. 23…”

“…In contrast to the existing mechanisms of pure proton storage and Zn 2+ intercalation, numerous studies in recent years have reported a H + /Zn 2+ co-storage mechanism in small quinone molecules, 62,67,68,[78][79][80][81][82][83] polymers, [84][85][86] and COFs. 69,75,87 The structures of these organic electrode materials are illustrated in Figure 6. It should be noted that the abovementioned organic compounds are either quinones or imines.…”

“…in organic electrode materials can only experience singleelectron reaction per active group while the Zn 2+ ions carry two positive charges. 88 Thus, the coordination reaction between Zn 2+ and the organic electrode materials take place in adjacent electrochemical active groups within one molecule 58,[69][70][71]75 or from adjacent molecules. 67,68,78 In either case, the utilization rate of active groups is limited due to the restrictions on their spatial location.…”

Covalent Organic Frameworks: Recent Progress in Biomedical Applications

“…Since the discovery of COFs by Yaghi in 2005, much research on the synthesis, properties, and diverse applications of COF materials has been conducted. COFs are crystalline porous polymers , that mainly comprise light elements, typically C, H, O, N and B, that are connected together through covalent bonds, such as imide, azine, imine, boronate ester, hydrazone, and other linkages. − Over the past two decades, a wide range of 2D and 3D COF structures have been realized and applied in many areas, such as gas storage, − photovoltaics, conductivity, − batteries, ,− catalysis, − optoelectronic devices, electrochemical sensing, and optical sensing because of their excellent features. Moreover, emerging COF materials with large surface areas and ultrathin structures allow for surface modification with versatile components, thus further enabling exquisite tailoring for biomedical applications, biosensors, and multifunctional bioelectronics. − Also, the different pore sizes and surface areas of 2D and 3D COF materials could lead to diverse results in biomedical research.…”