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Abstract Organic materials with redox‐active oxygen functional groups are of great interest as electrode materials for alkali‐ion storage due to their earth‐abundant constituents, structural tunability, and enhanced energy storage properties. Herein, a hybrid carbon framework consisting of reduced graphene oxide and oxygen functionalized carbon quantum dots (CQDs) is developed via the one‐pot solvothermal reduction method, and a systematic study is undertaken to investigate its redox mechanism and electrochemical properties with Li‐, Na‐, and K‐ions. Due to the incorporation of CQDs, the hybrid cathode delivers consistent improvements in charge storage performance for the alkali‐ions and impressive reversible capacity (257 mAh g−1at 50 mA g−1), rate capability (111 mAh g−1at 1 A g−1), and cycling stability (79% retention after 10 000 cycles) with Li‐ion. Furthermore, density functional theory calculations uncover the CQD structure‐electrochemical reactivity trends for different alkali‐ion. The results provide important insights into adopting CQD species for optimal alkali‐ion storage.
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High‐Rate Polymeric Redox in MXene‐Based Superlattice‐Like Heterostructure for Ammonium Ion Storage
Abstract Achieving both high redox activity and rapid ion transport is a critical and pervasive challenge in electrochemical energy storage applications. This challenge is significantly magnified when using large‐sized charge carriers, such as the sustainable ammonium ion (NH4+). A self‐assembled MXene/n‐type conjugated polyelectrolyte (CPE) superlattice‐like heterostructure that enables redox‐active, fast, and reversible ammonium storage is reported. The superlattice‐like structure persists as the CPE:MXene ratio increases, accompanied by a linear increase in the interlayer spacing of MXene flakes and a greater overlap of CPEs. Concurrently, the redox activity per unit of CPE unexpectedly intensifies, a phenomenon that can be explained by the enhanced de‐solvation of ammonium due to the increased volume of 3 Å‐sized pores, as indicated by molecular dynamic simulations. At the maximum CPE mass loading (MXene:CPE ratio = 2:1), the heterostructure demonstrates the strongest polymeric redox activity with a high ammonium storage capacity of 126.1 C g−1and a superior rate capability at 10 A g−1. This work unveils an effective strategy for designing tunable superlattice‐like heterostructures to enhance redox activity and achieve rapid charge transfer for ions beyond lithium.
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- Award ID(s):
- 2318105
- PAR ID:
- 10641531
- Publisher / Repository:
- Wiley Blackwell (John Wiley & Sons)
- Date Published:
- Journal Name:
- Advanced Energy Materials
- Volume:
- 14
- Issue:
- 42
- ISSN:
- 1614-6832
- Format(s):
- Medium: X
- Sponsoring Org:
- National Science Foundation
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