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.
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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