Emerging rechargeable aluminium batteries (RABs) offer a sustainable option for next-generation energy storage technologies with low cost and exemplary safety. However, the development of RABs is restricted by the limited availability of high-performance cathode materials. Herein, we report two polyimide two-dimensional covalent organic frameworks (2D-COFs) cathodes with redox-bipolar capability in RAB. The optimal 2D-COF electrode achieves a high specific capacity of 132 mAh g À 1 . Notably, the electrode presents long-term cycling stability (with a negligible � 0.0007 % capacity decay per cycle), outperforming early reported organic RAB cathodes. 2D-COFs integrate n-type imide and ptype triazine active centres into the periodic porous polymer skeleton. With multiple characterizations, we elucidate the unique Faradaic reaction of the 2D-COF electrode, which involves AlCl 2 + and AlCl 4 À dual-ions as charge carriers. This work paves the avenue toward novel organic cathodes in RABs.
The anion-intercalation chemistries of graphite have the potential to construct batteries with promising energy and power breakthroughs. Here, we report the use of an ultrathin, positively charged two-dimensional poly(pyridinium salt) membrane (C2DP) as the graphite electrode skin to overcome the critical durability problem. Large-area C2DP enables the conformal coating on the graphite electrode, remarkably alleviating the electrolyte. Meanwhile, the dense face-on oriented single crystals with ultrathin thickness and cationic backbones allow C2DP with high anion-transport capability and selectivity. Such desirable anion-transport properties of C2DP prevent the cation/solvent co-intercalation into the graphite electrode and suppress the consequent structure collapse. An impressive PF6−-intercalation durability is demonstrated for the C2DP-covered graphite electrode, with capacity retention of 92.8% after 1000 cycles at 1 C and Coulombic efficiencies of > 99%. The feasibility of constructing artificial ion-regulating electrode skins with precisely customized two-dimensional polymers offers viable means to promote problematic battery chemistries.
Neuartige Aluminium-Akkumulatoren (AlAKs) stellen eine nachhaltige Option für Energiespeichertechnologien der nächsten Generation mit niedrigen Kosten und beispielhafter Sicherheit dar. Die Entwicklung von AlAKs wird jedoch durch die begrenzte Verfügbarkeit von Hochleistungs-Kathodenmaterialien eingeschränkt. In diesem Artikel beschreiben wir zwei Polyimid-basierte zweidimensionale Covalent-Organic-Framework-(2D COF) Elektrodenmaterialien mit redox-bipolarer Fähigkeit in AlAKs. Die optimierte 2D-COF-Elektrode erreicht eine hohe spezifische Kapazität von 132 mAh g À 1 . Die Elektrode weist eine langfristige Zyklenstabilität auf (mit einem vernachlässigbaren Kapazitätsabfall von � 0.0007 % pro Zyklus) und übertrifft damit frühere Ergebnisse organischer AlAK-Kathoden. Unsere 2D-COFs beinhalten n-Type-Imide und p-Type-Triazine als aktive Zentren im periodisch-porösen Polymerskelett. Anhand umfänglicher Charakterisierungen erklären wir die ungewöhnliche Faradische Reaktion der 2D-COF-Elektrode, bei der AlCl 2 + -und AlCl 4 À Dualionen als Ladungsträger beteiligt sind. Diese Arbeit ebnet den Weg zu neuartigen organischen Kathodenmaterialien in AlAKs.
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