Organic redox-active polymers provide promising alternatives to metalcontaining inorganic compounds in Li-ion batteries (LIBs), whereas suffer from low actual capacities, poor rate/power capabilities, and inferior cycling stability. Herein, poly(anthraquinonyl sulfide)-coated carbon nanotubes (CNT@PAQS) are readily performed by in situ polymerization to form core–sheath nanostructures. Remarkably, flower-like PAQS nanosheets are interwoven around CNTs to synergistically create robust 3D hierarchical networks with abundant cavities, internal channels, and sufficiently-exposed surfaces/edges, thereby promoting electron transport and making more active sites accessible for electrolytes and guest ions. Apparently, the asfabricated CNT@PAQS cathode delivers the large reversible capacity (200.5 mAh g⁻¹ at 0.05 A g⁻¹), high-rate capability (161.5 mAh g⁻¹ at 5.0 A g⁻¹), and impressive cycling stability (retaining 88.0% over 1000 cycles). In addition, an asymmetric full-battery using CNT@PAQS as a cathode and cyclized polyacrylonitrile-encapsulated CNTs as an anode is assembled that delivers a high energy density of 86.3 Wh kg⁻¹, and retains 81.3% of initial capacity after 1000 cycles. This work opens up an efficient strategy to combine highly conductive and redox-active phases into core–sheath heterostructures to unlock the barrier of high-rate charge storage. The further integration of two polymer-based electrodes into asymmetric full cells would also consolidate the development of low-cost, sustainable, and powerful batteries.

Carbonyl polymers as booming electrode materials for lithium-organic batteries are currently limited by low practical capacities and poor rate performance due to their inherent electronic insulation and microscopic agglomeration morphologies. Herein graphene/carbonyl-enriched polyquinoneimine (PQI@Gr) composites were readily prepared by in situ hydrothermal polycondensation of dianhydride and anthraquinone co-monomer salts in the presence of graphene oxide (GO). Conductive graphene sheets derived from hydrothermal reduction of GO are fully sandwiched between densely interlaced quinone-containing polyimide nanosheets. Remarkably, the as-fabricated PQI@Gr cathodes exhibit much larger specific capacity (205 mAh g⁻¹ at 0.1 A g⁻¹), higher carbonyl utilization (up to 89.9%), and better rate capability (179.4 mAh g⁻¹ at 5.0 A g⁻¹) due to a surface-dominated capacitive process via fast kinetics compared to bare PQI electrode (162.5 mAh g⁻¹ at 0.1 A g⁻¹; 67.5%; 96.9 mAh g⁻¹ at 5 A g⁻¹). The capacity retention as high as 73% for PQI@Gr is also achieved over ultra-long 10 000 cycles at 5.0 A g⁻¹. Such outstanding electrochemical performances are attributable to the combined merits of polyimides and polyquinones, and robust 3D hierarchical heterostructures with efficient conductive networks, abundant porous channels for electrolyte infiltration and ion accessibility, and highly exposed carbonyl groups. This work offers new insights into the development of high-performance polymer electrodes for sustainable batteries.

Lithium-ion batteries using inorganic electrode materials have been long demonstrated as the most promising power supplies for portable electronics, electric vehicles, and smart grids. However, the increasing cost and descending availability of lithium resources in combination with the limited electrochemical performance and eco-sustainability have created serious concerns with the competitiveness of lithium-ion batteries. There is a pressing need for the discovery of new redox chemistries between the alternative host materials and charge carriers. Organic nonlithium batteries using organic electrodes have recently attracted considerable interests as the future substitutes for energy storage systems, because of their combined merits (e.g., natural abundance, rich chemistry of organics, rapid kinetics, and multielectron redox) of Li-free batteries and organic electrodes. Herein, an overview on the state-of-the-art developments of emerging carbonyl polymers for nonlithium metal-ion batteries is comprehensively presented with a primary focus on polyquinones and polyimides from the perspective of chain engineering. Six distinct categories, including monovalent (Na⁺, K⁺) and multivalent (Mg²⁺, Zn²⁺, Ca²⁺, Al³⁺) metal-ions batteries are individually outlined. Advantages of polymer electrode materials and characteristics of charge storage mechanisms are highlighted. Some key performance parameters such as specific capacity, rate capability, and cycle stability are carefully discussed. Moreover, aqueous nonlithium batteries based on carbonyl polymers are specially scrutinized due to the less reactivity of Li-free metals when exposed in aqueous electrolytes and ambient atmosphere. Current challenges and future prospects of developing polymer-based batteries are proposed finally. This review provides a fundamental guidance for the future advancement of next-generation sustainable batteries beyond lithium-ion batteries.