In:
Advanced Materials, Wiley, Vol. 34, No. 15 ( 2022-04)
Abstract:
2D transition metal carbides and/or nitrides, so‐called MXenes, are noted as ideal fast‐charging cation‐intercalation electrode materials, which nevertheless suffer from limited specific capacities. Herein, it is reported that constructing redox‐active phosphorus−oxygen terminals can be an attractive strategy for Nb 4 C 3 MXenes to remarkably boost their specific capacities for ultrafast Na + storage. As revealed, redox‐active terminals with a stoichiometric formula of PO 2 ‐ display a metaphosphate‐like configuration with each P atom sustaining three PO bonds and one PO dangling bond. Compared with conventional O‐terminals, metaphosphate‐like terminals empower Nb 4 C 3 (denoted PO 2 ‐Nb 4 C 3 ) with considerably enriched carrier density (fourfold), improved conductivity (12.3‐fold at 300 K), additional redox‐active sites, boosted Nb redox depth, nondeclined Na + ‐diffusion capability, and buffered internal stress during Na + intercalation/de‐intercalation. Consequently, compared with O‐terminated Nb 4 C 3 , PO 2 ‐Nb 4 C 3 exhibits a doubled Na + ‐storage capacity (221.0 mAh g ‐1 ), well‐retained fast‐charging capability (4.9 min at 80% capacity retention), significantly promoted cycle life (nondegraded capacity over 2000 cycles), and justified feasibility for assembling energy−power‐balanced Na‐ion capacitors. This study unveils that the molecular‐level design of MXene terminals provides opportunities for developing simultaneously high‐capacity and fast‐charging electrodes, alleviating the energy−power tradeoff typical for energy‐storage devices.
Type of Medium:
Online Resource
ISSN:
0935-9648
,
1521-4095
DOI:
10.1002/adma.202108682
Language:
English
Publisher:
Wiley
Publication Date:
2022
detail.hit.zdb_id:
1474949-X
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