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Scale Synthesis of Uniform Fe1-xS Nanomaterials and Its Application in Sodium Ion Batteries
Introduction:
In an effort to overcome the limitations of lithium-ion batteries in energy storage applications, sodium-ion batteries have gained significant attention due to their abundant sodium resources, widespread availability, and lower costs. This makes them a promising candidate for large-scale energy storage solutions. The development of high-performance anode materials is crucial for the commercial success of sodium-ion batteries. Among the various anode materials being explored, iron sulfide stands out due to its high theoretical capacity, excellent reversibility, abundant natural resources, and eco-friendly nature. These attributes make iron sulfide one of the most promising candidates for new anode materials.
It's widely acknowledged that nanostructures play a vital role in enhancing the electrochemical performance of nanomaterials. However, the complex experimental processes involved in synthesizing nanomaterials with specific nanostructures have hindered their practical application.
Recently, Professor Peng Shengjie from Nanjing University of Aeronautics and Astronautics developed a one-step vulcanization method to synthesize Fe1-xS nanomaterials with uniform morphology suitable for large-scale production. When used as an anode material in sodium-ion batteries, these materials exhibit remarkable rate performance and excellent cycle stability. Even after 2000 cycles at a current density of 10 A g-1, the reversible capacity retention remains at approximately 100%. Kinetic analysis indicates that the Ta capacitor plays a pivotal role in the material’s superior rate performance. Additionally, in-situ XRD characterization was utilized to study the sodium storage mechanism of Fe1-xS nanomaterials. Furthermore, when paired with Na0.6Co0.1Mn0.9O2, the Fe1-xS material forms a full sodium-ion battery cell that demonstrates high specific capacity and excellent cycle stability. Specifically, at a current density of 20 mA g-1, after 100 cycles, the capacity remains stable around 380 mAh g-1.
This work was published online in the journal Nano Energy (2017, 37, 81-89) under the title "Large-scale synthesis of highly uniform Fe1-xS nanostructures as a high-rate anode for sodium-ion batteries."
Graphical Introduction:
Figure 1. Physical Characterization of Fe1-xS Nanomaterials
(a, b) SEM images of Fe1-xS nanomaterials at different magnifications; (c, d) TEM images of Fe1-xS nanomaterials, inset: electron diffraction images; (e) EDX surface scan of each element of the Fe1-xS nanomaterial.
Figure 2. Electrochemical Performance of Fe1-xS Nanomaterials
(a) CV diagram of Fe1-xS nanomaterial; (b) charge and discharge curve; (c) cycle stability curve; (d) AC impedance diagram; (e) cycle stability curve under different charge and discharge rates.
Figure 3. Kinetic Properties of Fe1-xS Nanomaterials
(a) Rate performance curve of Fe1-xS nanomaterials; (b) charge-discharge curve at corresponding magnification; (c) CV curve at different sweep speeds; (d) log i vs. log v curve at corresponding redox peaks; (e) contribution of tantalum capacitance at different sweep speeds; (f) ratio of CV curve and corresponding tantalum capacitance when the sweep speed is 0.5 mV s-1.
Figure 4. Mechanism of Sodium Storage in Fe1-xS Nanomaterials
(a) In-situ XRD pattern of charge and discharge in the first week; (b) In-situ XRD pattern of charge and discharge in the third week; (c) XRD pattern at a certain charge and discharge potential.
Figure 5. Sodium Ion Full Cell Performance of Fe1-xS Nanomaterials
(a) Comparison of charge and discharge curves of Na0.6Co0.1Mn0.9O2 positive electrode and Fe1-xS negative electrode; electrochemical performance of Na0.6Co0.1Mn0.9O2/Fe1-xS full cell at current density of 20 mA g-1 (b, c) charge and discharge curve; (d) cycle stability curve.
Summary:
In this research, a uniform Fe1-xS nanostructure was successfully fabricated using a straightforward one-step vulcanization approach. As an anode material in sodium-ion batteries, it showcases impressive rate performance and prolonged cycle stability. Moreover, its outstanding sodium storage capabilities are clearly demonstrated in the sodium-ion full-cell configuration, further highlighting its potential for commercial applications.