Zhenyang Zhao

Electrochemical performance enhancement of graphite negative electrode by nano-metallic-oxides

Severe mechanical strain and rapid capacity decay during Li+ insertion/extraction processes restrict the potential applications of copper oxides as lithium-ion battery anode materials and modified electrode materials. Herein, a new method for obtaining nano-copper-oxides by decomposing Cu(CH3COO)2·H2O at high temperatures was put forward to improve the electrochemical properties of graphite. Moreover, the positive effects of LiAlO2 and Al2O3 on the electrochemical properties of natural graphite have been proved by our laboratory. Then, the modified graphite containing these nano-metallic-oxides was fabricated by solution mixing and high-temperature sintering. The discharge capacity was 493.3 mA h g−1 at 0.5C after 120 cycles, which significantly increased from 522.8 to 675.9 mA h g−1 after 155 cycles at 0.1C. Microstructural analysis showed that the thickness of the graphite layers and the degree of disorder were caused by the chemical reactions. First-principles calculations were performed to investigate the structure, conductivity and lithium storage properties of the graphite that was intercalated by different metal ions. The results prove that metal insertion can efficiently improve the performance of the material.

Distinctive electronic transport in pyridine-based devices with narrow graphene nanoribbon electrodes

Narrow zigzag graphene nanoribbons (ZGNRs) are used to construct two kinds of simple pyridine-based nano-devices, whose distinctive non-equilibrium electron transport properties are theoretically and thoroughly researched. Results show that the conjugated devices exhibit robust negative differential resistance (NDR) behavior and higher current, while the device based on a saturated bridge displays slight rectifying behavior and multistage NDR behavior, which can be used to build multi-functional devices and manifests its extensive potential applications. Analyses of the physical mechanisms for the devices are given. Remarkably, these pyridine-based devices possess two different transformations of transmission peaks and further there are two different explanations for the inner mechanisms of their NDR effects. We also present the effect of the width of the ZGNR electrodes on transport properties. Our findings provide valuable guidance for the design of new excellent organic-functional devices and raise the prospect of narrow ZGNR electrodes and pyridine-linked molecules for application in molecular electronics.

Wetting and coalescence of the liquid metal on the metal substrate

Molecular dynamics (MD) simulations are performed to investigate the wettability of liquid metal on the metal substrate. Results show that there exists different wettability on the different metal substrates, which is mainly determined by the interaction between the liquid and the substrate. The liquid metal is more likely to wet the same kind of metal substrate, which attracts the liquid metal to one side on the hybrid substrate. Exchanging the liquid metal and substrate metal has no effect on the wettability between these two metals. Moreover, the study of metal drop coalescing indicates that the metal substrate can significantly affect the coalescence behavior, in which the changeable wettability of liquid metal plays a predominant role. These studies demonstrate that the wetting behavior of liquid metal can be controlled by choosing the suitable metal substrate.