Bioinspired Redox-Active Catechol-Bearing Polymers as Ultrarobust Organic Cathodes for Lithium Storage

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^-1 at 5C and 320 mA h g^-1 at 30C in LIBs. The high ion and electron mobilities within the buckypaper also enable to register 96 mA h g^-1 (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.