1. Zero-strain Co-doped Na2FeP2O7/carbon delivers superior rate capability and long-cycle stability for sodium ion batteries.
- Author
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Gao, Jianhong, Chen, Ziwei, Cao, Wei, Chen, Jiale, Zhang, Ming, Lin, Feng, Li, Yongsheng, Ahmad, Waqar, Ling, Min, Liang, Chengdu, and Chen, Jun
- Subjects
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ELECTRIC batteries , *SODIUM ions , *DOPING agents (Chemistry) , *AMORPHOUS carbon , *DIFFUSION kinetics , *SOL-gel processes , *DENSITY functional theory , *SOL-gel materials - Abstract
• Innovative introduction of Co element into Na 2 FeP 2 O 7 material using a sol–gel method, as well as the reduction of active particles' size to nano-level and the formation of continuous carbon layer. • Taking advantage of "zero-strain" characteristic. • Enhanced charge/discharge capacity, superb rate capability and ultra-long cycling lifespan with a high capacity retention. • Experimental and theoretical investigation of the effect of Co doping with various measurements, including in-situ/ ex-situ characterizations, FIB-SEM, DFT calculations etc. Na 2 FeP 2 O 7 cathode material exhibits great promise in sodium ion batteries (SIBs), due to its low cost and high structural durability. Nevertheless, the intrinsically poor electronic conductivity and sluggish Na+ diffusion kinetics of Na 2 FeP 2 O 7 hinder its practical application. Herein, a synergistic cooperation of continuous amorphous carbon layer and optimized Co doping strategy is proposed to design high-performance SIB cathode (Co-doped Na 2 FeP 2 O 7 /C) via in-situ sol–gel method, where Co integration significantly enhances both the electronic conductivity and the Na+ diffusion kinetics, as confirmed by the combination of ex/in-situ characterizations and density functional theory calculations. Valuably, the synergy of amorphous carbon layer and appropriate Co doping restrains the structure stress to "zero-strain", Which remains beneficial for 0.10Co-NFO@C to display a high capacity of 96.12 mAh g-1 at 0.05C and a high-rate capacity of 61.75 mAh g-1 at 60C with the capacity retention of 79.9% after 5000 cycles. Moreover, optimized Co-doped Na 2 FeP 2 O 7 /C also shows outstanding cycling performance and rate capability when assembled into full batteries (hard carbon as the anode), demonstrating a reversible capacity of ∼110.9 mAh g-1 at 50 mA g−1, and a respectable capacity retention of 78.0% at 500 mA g−1 for 500 cycles. The strategy inspires new advances towards zero-strained cathode materials for high performance SIBs. [ABSTRACT FROM AUTHOR]
- Published
- 2024
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