Bismuth has emerged as a promising anode material for sodium‐ion batteries (SIBs), owing to its high capacity and suitable operating potential. However, large volume changes during alloying/dealloying processes lead to poor cycling performance. Herein, bismuth nanoparticle@carbon (Bi@C) composite is prepared via a facile annealing method using a commercial coordination compound precursor of bismuth citrate. The composite has a uniform structure with Bi nanoparticles embedded within a carbon framework. The nanosized structure ensures a fast kinetics and efficient alleviation of stress/strain caused by the volume change, and the resilient and conductive carbon matrix provides an interconnected electron transportation pathway. The Bi@C composite delivers outstanding sodium‐storage performance with an ultralong cycle life of 30 000 cycles at a high current density of 8 A g−1 and an excellent rate capability of 71% capacity retention at an ultrahigh current rate of 60 A g−1. Even at a high mass loading of 11.5 mg cm−2, a stable reversible capacity of 280 mA h g−1 can be obtained after 200 cycles. More importantly, full SIBs by pairing with a Na3V2(PO4)3 cathode demonstrates superior performance. Combining the facile synthesis and the commercial precursor, the exceptional performance makes the Bi@C composite very promising for practical large‐scale applications.

Organic cathode materials as economical and environment‐friendly alternatives to inorganic cathode materials have attracted comprehensive attention in potassium‐ion batteries (KIBs). Nonetheless, active material dissolution and mismatched electrolytes result in insufficient cycle life that definitely hinders their practical applications. Here, a significantly improved cycle life of 1000 cycles (80% capacity retention) on a practically insoluble organic cathode material, anthraquinone‐1,5‐disulfonic acid sodium salt, is realized, in KIBs through a solid‐electrolyte interphase (SEI) regulation strategy by ether‐based electrolytes. Such an excellent performance is attributed to the robust SEI film and fast reaction kinetics. More importantly, the ether‐electrolyte‐derived SEI film has a protective inorganic‐rich inner layer arising from the prior decomposition of potassium salts to solvents, as revealed by X‐ray photoelectron spectroscopy analysis and computational studies on molecular orbital energy levels. The findings shed light on the critical roles of electrolytes and the corresponding SEI films in enhancing performance of organic cathodes in KIBs.

Organic cathode materials have attracted extensive attention because of their diverse structures,f acile synthesis, and environmental friendliness.H owever,t hey often suffer from insufficient cycling stability caused by the dissolution problem, poor rate performance,a nd lowv oltages.A ni nsitu electropolymerization method was developed to stabilize and enhance organic cathodes for lithium batteries.4 ,4',4''-Tris-(carbazol-9-yl)-triphenylamine (TCTA) was employed because carbazole groups can be polymerized under an electric field and they may serve as high-voltage redox-active centers. The electropolymerized TCTAe lectrodes demonstrated excellent electrochemical performance with ah igh discharge voltage of 3.95 V, ultrafast rate capability of 20 Ag À1 ,a nd al ong cycle life of 5000 cycles.O ur findings provideanew strategy to address the dissolution issue and they explore the molecular design of organic electrode materials for use in rechargeable batteries.

Organic cathode materials have gained substantial attention in sodium‐ion batteries (SIBs) because of their low cost, structure versatility, and environmental friendliness. Nevertheless, the use of organic materials is plagued by the unsatisfactory cycling performance caused by dissolution of organic electrode materials, use of inappropriate electrolytes, and/or poor interfacial compatibility. In this work, an ultralong cycle life of SIBs through coupling an insoluble organic cathode, N, N′‐bis(glycinyl) naphthalene diimide, with ether‐based electrolytes, is realized. A thin and stable inorganic‐rich solid electrolyte interphase is constructed through a prior reduction of salt in the organic solvents in the ether‐based electrolytes, promising fast charge transfer kinetics and stable cycling performance of organic electrodes in SIBs. A superb long cycle life of 70 000 cycles at 10C is demonstrated, which is a new record for organic cathode materials in SIBs. The findings highlight the key role of electrolytes and electrolyte/electrode interfaces in furthering the practical prospects of organic electrodes.

Organic cathode materials have attracted extensive attention because of their diverse structures, facile synthesis, and environmental friendliness. However, they often suffer from insufficient cycling stability caused by the dissolution problem, poor rate performance, and low voltages. An in situ electropolymerization method was developed to stabilize and enhance organic cathodes for lithium batteries. 4,4′,4′′‐Tris(carbazol‐9‐yl)‐triphenylamine (TCTA) was employed because carbazole groups can be polymerized under an electric field and they may serve as high‐voltage redox‐active centers. The electropolymerized TCTA electrodes demonstrated excellent electrochemical performance with a high discharge voltage of 3.95 V, ultrafast rate capability of 20 A g−1, and a long cycle life of 5000 cycles. Our findings provide a new strategy to address the dissolution issue and they explore the molecular design of organic electrode materials for use in rechargeable batteries.