Advances in Electrochemical Energy Devices Constructed with Tungsten Oxide-Based Nanomaterials

Tungsten oxide-based materials have drawn huge attention for their versatile uses to construct various energy storage devices. Particularly, their electrochromic devices and optically-changing devices are intensively studied in terms of energy-saving. Furthermore, based on close connections in the forms of device structure and working mechanisms between these two main applications, bifunctional devices of tungsten oxide-based materials with energy storage and optical change came into our view, and when solar cells are integrated, multifunctional devices are accessible. In this article, we have reviewed the latest developments of tungsten oxide-based nanostructured materials in various kinds of applications, and our focus falls on their energy-related uses, especially supercapacitors, lithium ion batteries, electrochromic devices, and their bifunctional and multifunctional devices. Additionally, other applications such as photochromic devices, sensors, and photocatalysts of tungsten oxide-based materials have also been mentioned. We hope this article can shed light on the related applications of tungsten oxide-based materials and inspire new possibilities for further uses

Microstructure and electrochemical performance of thin film anodes for lithium ion batteries in immiscible Al-Sn system

The immiscible Al-Sn alloy thin films prepared by electron-beam deposition were first investigated as possible negative electrodes for lithium ion batteries. In the complex structure of the Al-Sn thin films, tiny Sn particles dispersed homogeneously in the Al active matrix. Their electrochemical characteristics were tested in comparison with the pure Al and Sn films. Cyclic voltammetry results indicated that the Li+-transport rates in these Al-Sn alloy films were significantly enhanced. Charge-discharge tests showed that the Al-Sn alloy film anodes had good cycle performance. The electrode with high Al content (Al-33 wt%Sn) delivered a high initial discharge capacity of 752 mAh g-1 while the electrode with high Sn content (Al-64 wt%Sn) had better cycleability with a stable specific capacity of about 300 mAh g-1 under 0.8 C rate. The good performance of these immiscible Al-Sn alloy film anodes was attributed to their unique microstructure. The mechanism of lithiation and delithiation reaction had been proposed based on cyclic voltammograms and impedance response of the Al-Sn alloy thin film electrodes. Our preliminary results demonstrate that the Al-Sn immiscible alloy is a potential candidate negative material for Li-ion battery. © 2008 Elsevier B.V. All rights reserved.Link_to_subscribed_fulltex

SiO–Sn2Fe@C composites with uniformly distributed Sn2Fe nanoparticles as fast-charging anodes for lithium-ion batteries

SiO-based materials represent a promising class of anodes for lithium-ion batteries (LIBs), with a high theoretical capacity and appropriate and safe Li-insertion potential. However, SiO experiences a large volume change during the electrochemical reaction, low Li diffusivity, and low electron conductivity, resulting in degradation and low rate capability for LIBs. Here, we report on the rapid crafting of SiO–Sn2Fe@C composites via a one-step plasma milling process, leading to an alloy of Sn and Fe and in turn refining SiO and Sn2Fe into nanoparticles that are well dispersed in a nanosized, few-layer graphene matrix. The Sn and Fe nanoparticles generated during the first Li-insertion process form a stable network to improve Li diffusivity and electron conductivity. As an anode material, the SiO–Sn2Fe@C composite manifests high reversible capacities, superior cycling stability, and excellent rate capability. The capacity retention is found to be as high as 95% and 84% at the 100th and 300th cycles under 0.3 ​C. During rate capability testing at 3, 6, and 11 ​C, the capacity retentions are 71%, 60%, and 50%, respectively. This study highlights that this simple, one-step plasma milling strategy can further improve SiO-based anode materials for high-performance LIBs

Sn buffered by shape memory effect of NiTi alloys as high-performance anodes for lithium ion batteries

By applying the shape memory effect of the NiTi alloys to buffer the Sn anodes, we demonstrate a simple approach to overcome a long-standing challenge of Sn anode in the applications of Li-ion batteries - the capacity decay. By supporting the Sn anodes with NiTi shape memory alloys, the large volume change of Sn anodes due to lithiation and delithiation can be effectively accommodated, based on the stress-induced martensitic transformation and superelastic recovery of the NiTi matrix respectively, which leads to a decrease in the internal stress and closing of cracks in Sn anodes. Accordingly, stable cycleability (630 mA h g(-1) after 100 cycles at 0.7C) and excellent high-rate capabilities (478 mA h g(-1) at 6.7C) were attained with the NiTi/Sn/NiTi film electrode. These shape memory alloys can also combine with other high-capacity metallic anodes, such as Si, Sb, Al, and improve their cycle performance. (c) 2012 Acta Materialia Inc. Published by Elsevier Ltd. All rights reserved

Oxygen-Incorporated and Polyaniline-Intercalated 1T/2H Hybrid MoS₂ Nanosheets Arrayed on Reduced Graphene Oxide for High-Performance Supercapacitors

This work synthesizes the hybrid 1T/2H phase MoS₂ nanosheets array on reduced graphene oxide for high-performance supercapacitors under extreme environmental temperature via oxygen incorporation and polyaniline intercalation method. The oxygen incorporation, which leads to the formation of MoS₂ with hybrid phase of 1T and 2H structure, and polyaniline intercalation provide excellent conductivity and expand the interlayer distance of MoS₂. Meanwhile, the sandwiched oxygen-incorporated MoS₂/polyaniline nanosheet array aligns on reduced graphene oxide, creating sufficient heterointerface among polyaniline, MoS₂, and reduced graphene oxide, which constructs a conducting network that is beneficial for charge transfer and structure stability. The obtained oxygen-incorporated MoS₂/polyaniline/reduced graphene oxide hierarchical nanosheets exhibit a capacitance of 752.0 F g^–1 at 1 A g^–1 in 1 M H₂SO₄ in a three-electrode system. When cycles at 50 A g^–1 for 50 000 cycles, it has a capacitance retention of 80.4 % for the initial cycle (282.3 F g^–1). The material shows excellent performance in an extremely wide range of temperatures. The symmetric cell has capacitances of 79.6, 100.1, and 122.0 F g^–1 at 2 A g^–1 at 0 °C, room temperature, and 50 °C and maintains about 89.9, 86.1, and 73.9% of the initial capacitance, respectively, after 30 000 cycles

Oxygen-Incorporated and Polyaniline-Intercalated 1T/2H Hybrid MoS₂ Nanosheets Arrayed on Reduced Graphene Oxide for High-Performance Supercapacitors

This work synthesizes the hybrid 1T/2H phase MoS₂ nanosheets array on reduced graphene oxide for high-performance supercapacitors under extreme environmental temperature via oxygen incorporation and polyaniline intercalation method. The oxygen incorporation, which leads to the formation of MoS₂ with hybrid phase of 1T and 2H structure, and polyaniline intercalation provide excellent conductivity and expand the interlayer distance of MoS₂. Meanwhile, the sandwiched oxygen-incorporated MoS₂/polyaniline nanosheet array aligns on reduced graphene oxide, creating sufficient heterointerface among polyaniline, MoS₂, and reduced graphene oxide, which constructs a conducting network that is beneficial for charge transfer and structure stability. The obtained oxygen-incorporated MoS₂/polyaniline/reduced graphene oxide hierarchical nanosheets exhibit a capacitance of 752.0 F g^–1 at 1 A g^–1 in 1 M H₂SO₄ in a three-electrode system. When cycles at 50 A g^–1 for 50 000 cycles, it has a capacitance retention of 80.4 % for the initial cycle (282.3 F g^–1). The material shows excellent performance in an extremely wide range of temperatures. The symmetric cell has capacitances of 79.6, 100.1, and 122.0 F g^–1 at 2 A g^–1 at 0 °C, room temperature, and 50 °C and maintains about 89.9, 86.1, and 73.9% of the initial capacitance, respectively, after 30 000 cycles