Self-Relaxant Superelastic Matrix Derived from C60 Incorporated Sn Nanoparticles for Ultra-High-Performance Li-Ion Batteries.

Homogeneously dispersed Sn nanoparticles approximately ⩽10 nm in a polymerized C60 (PC60) matrix, employed as the anode of a Li-ion battery, are prepared using plasma-assisted thermal evaporation coupled by chemical vapor deposition. The self-relaxant superelastic characteristics of the PC60 possess the ability to absorb the stress-strain generated by the Sn nanoparticles and can thus alleviate the problem of their extreme volume changes. Meanwhile, well-dispersed dot-like Sn nanoparticles, which are surrounded by a thin SnO2 layer, have suitable interparticle spacing and multilayer structures for alleviating the aggregation of Sn nanoparticles during repeated cycles. The Ohmic characteristic and the built-in electric field formed in the interparticle junction play important roles in enhancing the diffusion and transport rate of Li ions. SPC-50, a Sn-PC60 anode consisting of 50 wt % Sn and 50 wt % PC60, as confirmed by energy-dispersive X-ray spectroscopy analysis, exhibited the highest electrochemical performance. The resulting SPC-50 anode, in a half-cell configuration, exhibited an excellent capacity retention of 97.18%, even after 5000 cycles at a current density of 1000 mA g-1 with a discharge capacity of 834.25 mAh g-1. In addition, the rate-capability performance of this SPC-50 half-cell exhibited a discharge capacity of 544.33 mAh g-1 at a high current density of 10 000 mA g-1, even after the current density was increased 100-fold. Moreover, a very high discharge capacity of 1040.09 mAh g-1 was achieved with a capacity retention of 98.67% after 50 cycles at a current density of 100 mA g-1. Futhermore, a SPC-50 full-cell containing the LiCoO2 cathode exhibited a discharge capacity of 801.04 mAh g-1 and an areal capacity of 1.57 mAh cm-2 with a capacity retention of 95.27% after 350 cycles at a current density of 1000 mA g-1.

Pseudocapacitive Characteristics of Low-Carbon Silicon Oxycarbide for Lithium-Ion Capacitors.

Lithium-ion capacitors (LICs) and lithium-ion batteries (LIBs) are important energy storage devices. As a material with good mechanical, thermal, and chemical properties, low-carbon silicon oxycarbide (LC-SiOC), a kind of silicone oil-derived SiOC, is of interest as an anode material, and we have examined the electrochemical behavior of LC-SiOC in LIB and LIC devices. We found that the lithium storage mechanism in LC-SiOC, prepared by pyrolysis of phenyl-rich silicon oil, depends on an oxygen-driven rather than a carbon-driven mechanism within our experimental scope. An investigation of the electrochemical performance of LC-SiOC in half- and full-cell LIBs revealed that LC-SiOC might not be suitable for full-cell LIBs because it has a lower capacity (238 mAh g-1) than that of graphite (290 mAh g-1) in a cutoff voltage range of 0-1 V versus Li/Li+, as well as a substantial irreversible capacity. Surprisingly, LC-SiOC acts as a pseudocapacitive material when it is tested in a half-cell configuration within a narrow cutoff voltage range of 0-1 V versus Li/Li+. Further investigation of a "hybrid" supercapacitor, also known as an LIC, in which LC-SiOC is coupled with an activated carbon electrode, demonstrated that a power density of 156 000 W kg-1 could be achieved while maintaining an energy density of 25 Wh kg-1. In addition, the resulting capacitor had an excellent cycle life, holding ∼90% of its energy density even after 75 000 cycles. Thus, LC-SiOC is a promising active material for LICs in applications such as heavy-duty electric vehicles.

Oxidation-resistant hybrid metal oxides/metal nanodots/silver nanowires for high performance flexible transparent heaters.

Despite its excellent optical, electrical, mechanical, and thermal performances, a silver nanowire (AgNW)-based transparent conducting heater (TCH) still demonstrates several drawbacks such as facile nanowire breakdown on application of a high DC voltage, easy oxidation when exposed to harsh environments, leading to increased surface resistivity, and high resistance among wire junctions causing nonhomogeneous temperature profiles. To overcome these issues, the AgNW was hybridized with other transparent heating materials made of fluorine-doped tin oxide (FTO) thin films and NiCr nanodots (FTO/NiCr/AgNW). The dispersed NiCr nanodots (∼50 nm) and FTO thin films (∼20 nm) electrically bridge the nanowire junctions leading to a decreased sheet resistance and uniform temperature profiles. The hybrid transparent heater shows excellent optical transmittance (>90%) and high saturation temperature (162 °C) at low applied DC voltage (6 V). Moreover, the FTO/NiCr/AgNW heater exhibits a stable sheet resistance in a hostile environment, hence highlighting the excellent oxidation-resistance of the heating materials. These results indicate that the proposed hybrid transparent heaters could be a promising approach to combat the inherent problems associated with AgNW-based transparent heaters for various functional applications.

High thermal performance of SnO2:F thin transparent heaters with scattered metal nanodots.

Facile production and novel transparent heaters consisting of fluorine-doped tin oxide (SnO2:F or FTO) thin films covered with three different scattered metal nanodots (Cr-nd, NiCr-nd and Ni-nd) prepared by plasma-enhanced sputtering system and electron cyclotron resonance-metal organic chemical vapor deposition are investigated. The heaters exhibit excellent optical transmittances of over 85% and superior saturated temperatures of more than 80 °C when a relatively low 12 V DC is supplied. The scattered metal nanodots FTO heaters successfully improve the specific power of bare FTO heater by 21, 15, and 12% for NiCr-nd FTO, Cr-nd FTO, and Ni-nd FTO, respectively. These results reveal that the FTO transparent heaters with scattered metal nanodots are the suitable heating materials that can be applied for various functional devices.

Al-C hybrid nanoclustered anodes for lithium ion batteries with high electrical capacity and cyclic stability.

Structurally regulated and hybridized Al-C nanoclusters are prepared from C60 and Al precursors by thermal evaporation-combined plasma-enhanced chemical vapour deposition. The resulting Al-C hybrid nanoclustered anodes for Li-ion batteries exhibit a high reversible capacity of >900 mA h g(-1) at an optimized current density of 6 A g(-1) for over 100 cycles.

Effects of process parameters on sheet resistance uniformity of fluorine-doped tin oxide thin films.

An alternative indium-free material for transparent conducting oxides of fluorine-doped tin oxide [FTO] thin films deposited on polyethylene terephthalate [PET] was prepared by electron cyclotron resonance - metal organic chemical vapor deposition [ECR-MOCVD]. One of the essential issues regarding metal oxide film deposition is the sheet resistance uniformity of the film. Variations in process parameters, in this case, working and bubbler pressures of ECR-MOCVD, can lead to a change in resistance uniformity. Both the optical transmittance and electrical resistance uniformity of FTO film-coated PET were investigated. The result shows that sheet resistance uniformity and the transmittance of the film are affected significantly by the changes in bubbler pressure but are less influenced by the working pressure of the ECR-MOCVD system.

Comparison of characteristics of fluorine doped zinc and gallium tin oxide composite thin films deposited on stainless steel 316 bipolar plate by electron cyclotron resonance-metal organic chemical vapor deposition for proton exchange membrane fuel cells.

In order to replace the brittle graphite bipolar plates currently used for the PEMFC stack, coated SUS 316 was employed. As a metallic bipolar plate, coated SUS 316 can provide higher mechanical strength, better durability to shocks and vibration, less permeability, improved thermal and bulk electrical conductivity, as well as being thinner and lighter. To enhance the interfacial contact resistance and corrosion resistance of SUS 316, the deposition of GTO:F and ZTO:F composite films was carried out by ECR-MOCVD. The surface morphology of the films consisted of tiny elliptically shaped grains with a thickness of 1 microm. The corrosion current for GTO:F was 0.13 Acm(-2) which was much lower than that of bare SUS 316 (50.16 Acm(-2)). The GTO:F coated film had the smallest corrosion current due to the formation of a tight surface morphology with very few pin-holes. The GTO:F coated film exhibited the highest cell voltage and power density due to its lower ICR values.