ACS Applied Energy Materials
·
2020
·
IF 4.473
Jiahong Xun,Yu Zhang,Bo Zhang,Huayun Xu,Liqiang Xu
Here, we report a novel material structure for sodium ion battery cathodes. The material has an enormously enhanced conductive framework of Na2FePO4F (NFPF), combining both 1D carbon nanotube (CNT) and 2D graphene nanosheets (GNs). Uniform Na2FePO4F nanorods were synthesized first via a one-step hydrothermal method. Then, the highly efficient conductive network of NFPF@CNT&GN was synthesized with a straightforward mechanical ball milling technique. The obtained NFPF@CNT&GN shows a reversible capacity of 67.5 mA h g–1 at 10C rate, which exceeds all of the published results for NFPF to date. Remarkably, the degradation rate is only 0.02% per cycle even after 2500 cycles at the 5C rate. The electrochemical impedance spectroscopy kinetic study demonstrates that the superior electrochemical properties for NFPF@CNT&GN should be attributed to the great improvement of the electronic conductivity and sodium-ion diffusion ability.
研究领域:
材料科学
·
电化学
✓ 已验证
DOI
高影响因子
ELECTROCHIMICA ACTA
·
2021
·
IF 6.901
Haiming Li,Tailin Wang,Xue Wang,Guangda Li,Jianxing Shen,Jinling Chai
An Al-doped Na 2 FePO 4 F/mesoporous carbon nanonetwork derived from an metal–organic framework (MOF) material, was synthesized using a simple solid-state reaction method and evaluated as a promising cathode material for sodium-ion batteries. The MIL-53(Al) derived mesoporous carbon nanonetwork coating can enhance electron conductivity in Na 2 FePO 4 F cathode materials. The doping derived from MIL-53(Al) caused no damage to the crystal structure of the material, and Fe 2+ site was replaced by Al 3+ successfully. Therefore, the Al-doped Na 2 FePO 4 F/MOF-C composites exhibit substantial improvements in electrochemical performance in terms of rate capability and cycle performance. When current density increased from 0.1 C to 5 C, the specific capacity of Na 1.94 Fe 0.94 Al 0.06 PO 4 F/MOF-C only decreased from 115.2 mAh g −1 to 63.2 mAh g −1 ; thus, the composite presented outstanding rate capability. Moreover, an excellent capacity retention of 70.3% was maintained from the initial value of 70.4 mAh g −1 to 49.5 mAh g −1 after the 500th cycle at 5 C. This study provides insights into designing high-performance cathode materials by improving structural stability and the electrical conductivity induced by MOF-derived carbon coating and metal doping.
研究领域:
材料科学
·
电化学
✓ 已验证
DOI
高影响因子
JOURNAL OF ELECTROANALYTICAL CHEMISTRY
·
2022
·
IF 4.598
Mingjun Lu,Rongting Guo,Wei Li,Yiju Lv,Fushun Tang,Weiyi Feng,Zheng Liu,Guo-Cheng Han,Zhihua Zhan
The interfacial characterization of the cathode material Na 2 FePO 4 F with carbon capping material Na 2 FePO 4 F@C taking bagasse as the carbon source is reported. Both the higher-capacity Na 2 FePO 4 F@C material (93 mAh/g) and lower-capacity Na 2 FePO 4 F material (10 mAh/g) showed different degrees of capacity decay during cycling. The rupture and spontaneous repair process of the solid electrolyte interface (SEI) film resulting in increased impedance and blocked charge transfer, as well as irreversible changes in the surface microstructure of the electrode material after cycling, which are responsible for the decrease in capacity. The XRD and FTIR results before and after cycling shown that the characteristic peaks of the carbon coated material Na 2 FePO 4 F@C and raw material Na 2 FePO 4 F were consistent, indicated that their functional groups and crystalline structures are not the main causes of capacity decay at low cycling times (within 50 cycles).
研究领域:
电化学
·
材料科学
·
能源存储
·
电池技术
·
界面化学
·
无机非金属材料
✓ 已验证
DOI
高影响因子
Advanced Science
·
2019
·Vol. 6
·期 13
·1900649
·
IF 15.804
Fanfan Wang,Ning Zhang,Xudong Zhao,Lixuan Wang,Jian Zhang,Tianshi Wang,Fanfan Liu,Yongchang Liu,Li-Zhen Fan
In this paper, the synthesis of ultrasmall Na 2 FePO 4 F nanoparticles (≈3.8 nm) delicately embedded in porous N-doped carbon nanofibers (denoted as Na 2 FePO 4 F@C) by electrospinning is reported. The as-prepared Na 2 FePO 4 F@C fiber film tightly adherent on aluminum foil features great flexibility and is directly used as binder-free cathode for sodium-ion batteries, exhibiting admirable electrochemical performance with high reversible capacity (117.8 mAh g −1 at 0.1 C), outstanding rate capability (46.4 mAh g −1 at 20 C), and unprecedentedly high cyclic stability (85% capacity retention after 2000 cycles). The reaction kinetics and mechanism are explored by a combination study of cyclic voltammetry, ex situ structure/valence analyses, and first-principles computations, revealing the highly reversible phase transformation of Na 2 Fe II PO 4 F ↔ NaFe III PO 4 F, the facilitated Na + diffusion dynamics with low energy barriers, and the desirable pseudocapacitive behavior for fast charge storage. Pouch-type Na-ion full batteries are also assembled employing the Na 2 FePO 4 F@C nanofibers cathode and the carbon nanofibers anode, demonstrating a promising energy density of 135.8 Wh kg −1 and a high capacity retention of 84.5% over 200 cycles. The distinctive network architecture of ultrafine active materials encapsulated into interlinked carbon nanofibers offers an ideal platform for enhancing the electrochemical reactivity, electronic/ionic transmittability, and structural stability of Na-storage electrodes.
研究领域:
材料科学
·
电化学
·
能源存储
✓ 已验证
DOI
高影响因子
CERAMICS INTERNATIONAL
·
2012
·Vol. 39
·期 5
·5379-5385
·
IF 1.751
Jingjing Zhou,Jiefeng Zhou,Yuanhao Tang,Yujing Bi,Chenyun Wang,Deyu Wang,Siqi Shi
Using NaF as the only Na precursor, fluorophosphate Na 2 FePO 4 F/C materials have been synthesized via the solid-state reaction. Na 2 FePO 4 F starts to form at 300 °C, becomes the sole crystalline form between 400 and 600 °C, and decomposes at 650 °C. Comparing with the theoretical capacity of 124 mAh g −1 , the sample prepared at 600 °C delivered a discharge capacity of 118 mAh g −1 . The outstanding electrochemical performance is believed to result from the good crystallization and high purity of the synthesized materials . The capacity retentions at 0.5 C and 2 C are 95.8% and 89.8%, respectively, of that at 0.05 C. Furthermore, a discharge capacity of 122 mAh g −1 is maintained under the cycling between 2.0 and 5.2 V vs. Li/Li + , indicating that the second Na + is not extracted from the Na 2 FePO 4 F lattice.
研究领域:
材料科学
·
电化学
·
能源存储
·
无机化学
·
固体化学
✓ 已验证
DOI
高影响因子
ACS Applied Materials & Interfaces
·
2026
·
IF 7.8
Wenxin Xia,Huan Ye,Guoxing Ren,Wenqing Zhao,Jiayu Hao,Wanwan Hong,Wenhua Xu,Dongfu Liu,Qiqi Huang,Jianwei Zhao,Songwen Xiao,Zhongwei Zhao
Na2FePO4F (NFPF) is a promising cathode material for sodium-ion batteries, yet it is still confronted with a cost–performance trade-off. In this study, a low-cost preparation method of high-performance NFPF cathode materials was proposed via an Al-doping strategy, using commercial FePO4 without premodification. The effect of the Al content on the crystal structure, sodium-ion diffusion kinetics, and electrochemical performance of NFPF was investigated in detail. X-ray diffraction and Rietveld refinements confirmed the high-purity phase. Na1.98Fe0.98Al0.02PO4F/C (NFPF-Al0.02) showed an excellent rate capability (57.7 vs 44.5 mAh·g–1 at 5.0 C) and better cycling stability (93.6% vs 66.7% after 100 cycles at 0.5 C) than the undoped NFPF sample. NFPF-Al0.02 also exhibited an excellent capacity retention of 84.6% after 1000 cycles at 5.0 C. GITT, CV, and EIS results revealed an order-of-magnitude increase in the sodium-ion diffusion coefficient of Al-doped NFPF-Al0.02 compared to that of pristine NFPF. A cost–performance comparison between this work and previous studies was conducted. In summary, this innovative method, which can produce high-performance NFPF cathode materials at low cost, is anticipated to significantly promote the commercialization of NFPF-based sodium-ion batteries.
✓ 已验证
DOI
PubMed
高影响因子
IONICS
·
2025
·
IF 2.6
Li Zhongyong,Zhang Dandan,Xiao Dong,Fan Hui,Mishra Yogendra Kumar,Xiong Jian
As an iron-based fluorophosphate with a two-dimensional layered structure, Na₂FePO₄F (NFPF) has become an ideal cathode material for energy storage applications due to its low cost, high safety, and structural stability. However, the inherently low conductivity and limited kinetic behavior of NFPF result in inferior electrochemical performance, which hinders its commercialization. Herein, we employed a one-step carbon–nitrogen co-doping method to modify NFPF. First, carbon coating effectively enhances the conductivity of the NFPF cathode. Moreover, nitrogen doping introduces additional vacancies and active sites in the carbon layer, providing more Na⁺ diffusion channels. The NFPF/PVP material, synthesized using polyvinylpyrrolidone (PVP) as both the nitrogen and carbon source, delivers a specific capacity of 119 mAh g⁻ 1 at 0.1 C, an excellent rate capability of 90 mAh g⁻ 1 at 10 C, and unprecedented long-term cycling stability (81.9% capacity retention after 2000 cycles). These properties are significantly superior to those of previously reported NFPF cathode materials. Furthermore, electrochemical impedance spectroscopy (EIS) revealed that the charge transfer resistance of NFPF/PVP (123.59 Ω) is much lower than that of pristine NFPF (500.23 Ω), indicating facilitated charge transfer and faster Na⁺ transport kinetics. The Na⁺ diffusion coefficient of NFPF/PVP (4.78 × 10⁻ 11 cm 2 s⁻ 1 ) is two orders of magnitude higher than that of NFPF (3.35 × 10⁻ 13 cm 2 s⁻ 1 ), further demonstrating that the PVP-derived nitrogen-doped carbon coating effectively improves the reaction kinetics of NFPF. This study provides new strategies and insights for developing cost-effective and high-performance NFPF-based materials.
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