Redox-active catechols are bioinspired precursors for ortho-quinones that are characterized by higher discharge potentials than para-quinones, the latter being extensively used as organic cathode materials for lithium ion batteries (LIBs). Here, this study demonstrates that the rational molecular design of copolymers bearing catechol- and Li ion-conducting anionic pendants endow redox-active polymers (RAPs) with ultrarobust electrochemical energy storage features when combined to carbon nanotubes as a flexible, binder-, and metal current collector-free buckypaper electrode. The importance of the structure and functionality of the RAPs on the battery performances in LIBs is discussed. The structure-optimized RAPs can store high-capacities of 360 mA h g at 5C and 320 mA h g at 30C in LIBs. The high ion and electron mobilities within the buckypaper also enable to register 96 mA h g (24% capacity retention) at an extreme C-rate of 600C (6 s for total discharge). Moreover, excellent cyclability is noted with a capacity retention of 98% over 3400 cycles at 30C. The high capacity, superior active-material utilization, ultralong cyclability, and excellent rate performances of RAPs-based electrode clearly rival most of the state-of-the-art Li ion organic cathodes, and opens up new horizons for large-scalable fabrication of electrode materials for ultrarobust Li storage.

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Redox-active conjugated microporous polymers (RCMPs) polymerized by conventional methods are commonly obtained as irregular insoluble solid particles making the electrode processing difficult. In this work, the synthesis of RCMP based on anthraquinone moieties (IEP-11) is developed via a two-step pathway combining miniemulsion and solvothermal techniques that results in polymer nanostructures that are much easier to disperse in solvents facilitating the fabrication of electrodes. Interestingly, this synthetic approach is also found to have an important impact on the inherent morphology of IEP-11 that exhibits a dual porosity combining micro and mesopores with a specific surface area as high as 2200 m 2 g −1 , which is one of the highest values reported for RCMPs. Moreover, the compactness of the electrodes is also improved, the resulting electrodes have triple the density than those obtained with conventional methods. Consequently, when these electrodes are tested as cathodes in Li-ion battery, they deliver high gravimetric capacities (≈100 mAh g −1 ) and extraordinary rate capability keeping 76% of discharge capacity when charged-discharged in only 12 min (@5 C). Moreover, the insoluble and robust conjugated porous structure provides IEP-11-E12 with an unprecedented cycling stability retain ≈90% and ≈60% of its initial capacity after 5000 (@2 C) and 80 000 cycles (@30 C), respectively.

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DFT calculations reveal interesting structure–property relationships of the redox potentials of phenazines in non-aqueous media.

Redox-active organic compounds have become promising electrode materials for the development of more sustainable, economical, and safer batteries. However, their high electrochemical performance is inherently associated with the use of low mass-loading electrodes with high carbon content, which collectively hinders their applicability in real batteries. This work presents an innovative approach for developing high-performance and practical organic electrodes through the synthesis of anthraquinone-based conjugated microporous polymers in the presence of carbon nanostructures and further processing into self-supported buckypaper electrodes. This effective method enables high-mass-loading hybrid electrodes (up to 60 mg cm–2) with low carbon content (20 wt %), which attained high gravimetric capacity (83.7 mAh gelectrode –1), high areal capacity (6.3 mAh cm–2), good rate capability (0.8 mAh cm–2 at 10C), and remarkable cycle stability (>80% capacity retention over 1000 cycles). These are the highest values reported for an organic electrode, constituting a great leap forward in the development of practical organic batteries.

are limited by high cost, safety issues, poor recycling infrastructure, and growing concerns of resource scarcity. [4,5] Therefore, in the quest of finding alternative sustainable energy storage solutions, systems based on multivalent chemistries, such as Ca 2+ , Mg 2+ , Zn 2+ , Al 3+ , etc., should provide ample opportunities owing to their greater abundance, lower costs, superior safety features, in addition to their significantly higher volumetric energy densities. [6][7][8][9][10][11] In particular, zinc metal batteries (ZMBs) are highly intriguing because Zn anode shows high specific capacity (820 mAh g −1 ), high volumetric capacity of 5851 mAh cm −3 , nontoxicity, nonflammability, cost-effectiveness, large production, and easy processing. [12][13][14][15][16][17] Moreover, differently from other multivalent chemistries (Ca 2+ , Mg 2+ , Al 3+ ), the relatively higher redox potential of Zn (−0.76 V vs standard hydrogen electrode) makes it the only feasible choice as reversible anode for aqueous electrolytes. Certainly, taking advantage of the potentially large voltage window (>2 V) and high ionic conductivity of aqueous electrolytes, aqueous zinc metal batteries (AZMBs) might present an excellent high energy/power trade-off which is triggering the growing interest of this technology in the last years. [18,19] To date, AZMBs are mainly based on inorganic intercalation/ conversion cathode materials such as metal oxides (manganese, vanadium, etc.), transition metal dichalcogenides, polyanionic olivine-based phosphates, and Prussian blue analogs. [12,13,18,19] However, these cathode materials resulted in poor cell performances, exhibiting slow kinetics, low round-trip efficiency, and unstable cycling. This is due to the large cation size which hinders interfacial charge transfer and provokes strong electrostatic interactions between the highly charged Zn 2+ and the host inorganic framework causing destabilization of the crystal lattice and significant volume changes upon intercalation/deintercalation. [6][7][8][9][10][11] It is also important to highlight that most of these multivalent cathodes still involve toxic and/or environmentally unfriendly elements (except widely used MnO 2 ), which make further steps critical toward accomplishment of large-scale, sustainable energy storage systems. Therefore, the main challenge Aqueous zinc-metal batteries (AZMBs) are predicted to be an attractive solutions for viable, high-performance, and large-scale energy storage applications, but their advancement is greatly hindered by the lack of adequate aqueous electrolytes and sustainable cathodes. Herein, an ultra-robust Zn-polymer AZMB is demonstrated using poly(catechol) redox copolymer (P(4VC 86 -stat-SS 14 )) as the cathode and concentrated Zn(TFSI) 2 aqueous solution as stable electrolyte. The Zn(TFSI) 2 electrolyte shows enhanced iontransport properties and confers improved (electro)chemical compatibility with superior cell performance compared to traditional ZnSO 4 . The assembled Zn||P(4VC 86 -stat-SS 14 ) (2.5 mg cm ...

Organic electrode materials capable of reversible coordination/uncoordination of both mono- and multivalent ions in aqueous electrolytes are desired to develop safe, sustainable, and cost-effective water-based batteries. Here, we demonstrate the universality of bioinspired redox-active polymers bearing catechol pendants to reversibly coordinate/uncoordinate numerous cations including H+ and Li+ to Zn2+ and Al3+ with fast kinetics and ultralong cyclability. This unprecedented versatility is based on a catecholato–metal cation complex (Cat2–(mM n+)) charge storage mechanism that dictates the overall electrochemistry: formation of stronger complexes in M+ < M2+ < M3+ order resulted in a huge redox potential increment that might be used to tune the operating voltage of the battery.