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A ladder‐type rigid‐coplanar polymer with highly ordered molecular arrangement has been designed via a covalent cycloconjugation conformational strategy. Benefitting from the extended π‐electron delocalization in the highly aromatic ladder‐type polymeric backbone, the prepared polymer exhibits fast intra‐chain charge transport along the polymeric chain, realizing extraordinary proton‐storage capability in aqueous proton batteries.Affordable and safe aqueous proton batteries (APBs) with unique "Grotthuss mechanism," are very significant for advancing carbon neutrality initiatives. While organic polymers offer a robust and adaptable framework that is well‐suited for APB electrodes, the limited proton‐storage redox capacity has constrained their broader application. Herein, a ladder‐type polymer (PNMZ) has been designed via a covalent cycloconjugation conformational strategy that exhibits optimized electronic structure and fast intra‐chain charge transport within the high‐aromaticity polymeric skeleton. As a result, the polymer exhibits exceptional proton‐storage redox kinetics, which are evidenced by in‐operando monitoring techniques and theoretical calculations. It achieves a remarkable proton‐storage capacity of 189 mAh g−1 at 2 A g−1 and excellent long‐term cycling stability, with approximately 97.8 % capacity retention over 10,000 cycles. Finally, a high‐performance all‐polymer APB device has been successfully constructed with a desirable capacity retention of 99.7 % after 6,000 cycles and high energy density of 56.3 Wh kg−1. [ABSTRACT FROM AUTHOR]

Proton is a charge carrier with the smallest ionic size and quickest kinetics, making aqueous proton batteries (APBs), a promising technology for safe and profitable energy storage systems. Despite being potential electrode materials, organic compounds have not yet been fully investigated in terms of proton storage properties and APB applications due to their low capacity and unstable cycle life in aqueous electrolytes. Herein, a novel redox‐active polymer (PDPZ) with diquinoxalino‐phenazine as the structural unit has been designed, which is further integrated with MXene nanosheets to construct a flexible PDPZ@MXene electrode material with a rapid and ultra‐stable proton storage behavior. In‐operando monitoring techniques, i.e., in situ Raman and in situ FTIR, demonstrate the highly reversible redox reaction between CN and CN/NH bonds in electro‐active PDPZ molecule with the strong proton absorption ability. Theoretical calculation further proves the electron transfer from MXene to PDPZ promotes the redox reaction of the PDPZ@MXene electrode. As a result, a flexible APB device is developed with a considerable energy density (64.3 mWh cm−3), a supercapacitor‐level power density (6000 mW cm−3), and a record lifespan with ≈98.2% capacity retention over 10 000 cycles, revealing its potential applications in satisfying the various requirements of energy storage systems. [ABSTRACT FROM AUTHOR]

[Display omitted] • A rod-like phenazine-based organic electrode is designed and prepared via a facile dehydration. • In-situ analysis proves a fast, stable and efficient proton storage process in the organic electrode. • C N electroactive regions in each molecule can be simultaneously coordinated with two protons. • The phenazine-based organic electrode delivers a large proton storage capacity of ∼ 218 mAh g−1. • Soft-package and wire-shaped aqueous proton batteries are constructed for portable/wearable electronics. Aqueous proton batteries (APBs) have aroused attention because of the proton as charge carrier with smaller ionic size and faster kinetics when compared to the metallic ions in aqueous solutions. Although phenazine-based organic compounds with available redox-active sites are considered as promising organic electrode materials, the comprehensive study of their proton-storage behaviors and APB applications is still lacking so far. Herein, a rod-like diquinoxalino-phenazine (DPZ) organic compound is designed and synthetized via a facile dehydration approach. In-situ Raman investigation and theoretical calculation are conducted to probe into the proton redox process of DPZ organic electrode for the first time. It is demonstrated that three C N electroactive regions in each DPZ molecular unit could be simultaneously coordinated with two protons and the redox reaction between C N and C N bonds is highly reversible upon proton insertion/extraction. As expected, the DPZ organic electrode delivers a large proton-storage capacity of ∼ 218 mAh/g and long-term cycle performance without obvious dissolubility in acidic aqueous electrolyte. For real applications, soft-package and wire-shaped APBs based on such DPZ organic electrode are constructed, and they both achieve outstanding electrochemical characteristics, revealing their great potential applications in low-cost, high-safety, and high-performance energy technologies and portable/wearable electronics. [ABSTRACT FROM AUTHOR]

Owing to the proton as charge carrier with the smallest ionic size and fastest kinetics, aqueous proton batteries (APBs) with high safety and low cost are of great promise as flexible energy storage devices for portable/wearable electronics. Although Hexaazatrinaphthalene (HATN) is regarded as a potential organic electro-active material, the sluggish electron transfer and low tapped density of HATN seriously hinder its application as flexible electrode with high performance. Herein, we report a self-standing and binder-free HATN@MXene composite film electrode with high tapped density (∼2.21 g cm−3) for flexible APBs. In such film electrode, the HATN nanowires are encapsulated between the MXene flakes to construct a 3D lamination-like robust and conductive network to facilitate the electron transmission. As a result, the HATN@MXene film electrode delivers superior proton storage behaviors with a specific capacity as high as 516.2 mAh cm−3 (or 233.6 mA h g−1) in aqueous acidic electrolyte, while the reversible redox process upon proton uptake/removal is further revealed by in-situ Raman investigation. For real-life application, a high-performance flexible APB is assembled with high energy density (58.5 mWh cm−3) and long-term cycle performance upon the straight and bent states, suggesting its great potential for portable/wearable electronics. • A flexible and freestanding HATN@MXene composite film has been put forward. • Such composite film exhibits high tapped density and electronic conductivity. • Superior proton storage behaviors are achieved in composite film electrode. • Proton redox process is elucidated by DFT calculation and in-situ Raman investigation. • A flexible aqueous proton battery with reliable performance is constructed. [ABSTRACT FROM AUTHOR]

Although Polyindole (Pind) with a π-conjugated polymeric structure has been regarded as a promising organic material, the loosely packed and brittle backbones still hinder its long-term usage stability for various applications. Herein, a novel Pind/MXene composite with a 3D robust architecture has been developed by confining Pind nanoparticles in layered MXene through a simple and mild polymerization approach, which shows unique dual functionality for energy storage and corrosion protection for the first time. On the one hand, the Pind/MXene composite as an electrode material exhibits a rapid, reversible, and stable energy storage behavior with a large proton-storage capacity of 118 mAh g−1 and excellent cycle stability (∼98.2 % after 2000 cycles) in aqueous electrolyte. On the other hand, the Pind/MXene composite as an anti-corrosion additive is introduced into the epoxy resin to achieve a coating, which shows a long-term anti-corrosion performance with a low corrosion rate of 9.17 × 10−6 mm a−1 and a high corrosion inhibition efficiency of 99.72 %. Furthermore, theoretical calculations prove the obvious electron transfer between Pind and MXene, endowing the Pind/MXene composite with enhanced redox capability, high electrochemical activity and robust structural stability, suggesting its great potential as the bi-functional material for high-performance energy storage and corrosion protection. [Display omitted] • A bi-functional Polyindole-based composite material is proposed via a facile approach. • Polyindole nanodots are anchored on MXene to construct a 3D robust architecture. • Calculated and testing results reveal high electrochemical activity and redox capability. • The composite holds great potential for proton storage and corrosion protection. [ABSTRACT FROM AUTHOR]

[Display omitted] • A redox-active and π-electron delocalized polymer material is constructed with extended imine-conjugation. • Optimized molecular orbital endows an extremely small LUMO value of −3.26 eV in the polymer material. • Such polymer electrode shows large proton-storage capacity and long-term stability over 10,000 cycles. • Proton-storage redox behaviors are elucidated by multiple in-operando techniques and theoretical calculations. • A soft-package aqueous proton battery (APB) is constructed with reliable performances. Due to the unique "Grotthus mechanism" of the proton as the charge carrier, aqueous proton batteries (APBs) have the potential to become a type of feasible energy storage device with low cost and high security. Organic polymers with tunable molecule structures are promising for APB electrodes, whereas unsatisfactory redox capacity and low electron affinity hinder their real applications. Herein, a highly redox-active polymer, poly(diquinoxalino-phenazine) (PDQPZ), has been designed and synthesized with extended imine-conjugated polymeric backbones. Beneficial from the reasonable molecular configuration, the PDQPZ polymer shows extensive electron delocalization and optimized molecular orbitals with an extremely small LUMO value of −3.26 eV, leading to excellent electron affinity and high redox activity for fast, ultra-stable and extraordinary proton storage, which are further demonstrated by localized orbital locator-π (LOL-π) and iso -chemical shielding surface (ICSS) techniques. As such, the PDQPZ polymer as electrode material possesses a superior proton-storage capacity of 205.2 mAh g−1 and excellent cycling stability after 10,000 cycles with as low as 0.0008% decline per cycle. Multiple in-operando monitoring techniques further confirm highly reversible proton uptake/removal and the protonation pathways are proposed in detail. Finally, a high-performance and long-life APB device has been fabricated and operated over a wide temperature range. [ABSTRACT FROM AUTHOR]