We investigated electrochemical performance of natural graphite surface-treated with aluminum compared to that of untreated graphite. Aluminum triethoxide was used as the treatment source. In the treatment process, the drying temperature has critical influence on electrochemical performance of the treated samples. The surface property of treated samples was investigated by scanning electron microscopy and Raman spectroscopy. The E 2g vibration mode of the treated sample was sharpened and shifted upward, whereas no remarkable changes were found in A 1g mode. The electrochemical performance improved markedly with Al treatment. The impedance measurement shows that the Al treated sample had much smaller charge-transfer resistance during cycling.Rechargeable lithium-ion batteries, using a carbon material as anode and transition metal oxide, such as LiCoO 2 , LiMn 2 O 4 , or LiNiO 2 , as cathode, have been developed. Recently, there has been a lot of research to improve battery performance, usually carried out on various types of carbonaceous material ranging from graphite to disordered carbon by control of various properties such as structure, 1-3 surface modification. 4-6 Among the several types of carbonaceous materials, natural or synthetic graphitic carbons are commonly found in most commercial products in the market today due to their merits such as flat and low working voltage with respect to lithium metal and relatively high coulombic efficiency. Specifically, natural graphite can be thought of as a potential material for anodes in lithium-ion batteries due to cost considerations. 7 However, it is known that it is difficult to control the key parameters of natural graphite that affect their characteristics for use as anodes because carbon materials have large variations in their electrical properties. Among the various parameters of natural graphite, surface property is one of the critical factors that affect electrochemical performance, such as reversible specific capacity, cycle life, and rate capability. 7 In this paper, we report on an investigation of the influence of surface and/or structure modification of natural graphite by introducing aluminum compound for electrochemical performance of anodes in lithium-ion batteries. ExperimentalAluminum treated samples were prepared by aluminum triethoxide (Al͑OC 2 H 5 ͒ 3 ), Soekawa Chemicals͒ treatment on NG2 ͑Kansai chemicals͒. The NG2 graphite was soaked in ethanol solution containing 10 wt % aluminum triethoxide, followed by ultrasonic treatment for 3 h, filtration, and drying at various temperatures for 1 day to remove residual alcohol. Untreated samples were also prepared by alcohol soaking without Al triethoxide, ultrasonic treatment, and heat-treatment for comparison with Al-treated one. The infrared ͑IR͒ spectra of the samples were measured with a Jasco FT/IR 350 by KBr method. An X-ray diffractometry ͑XRD, Rigaku RINT2500͒ with Cu K␣ radiation was used to measure Bragg reflections from untreated and treated NG2. Raman scattering measurements were carried...

The purpose of this research is to demonstrate a new design for a cortisol immunosensor for the noninvasive and quantitative analysis of salivary cortisol. We propose a cortisol immunosensor with a fluid control mechanism which has both a vertical flow and a lateral flow. The detected current resulting from a competitive reaction between the sample cortisol and a glucose oxidase (GOD)-labeled cortisol conjugate was found to be inversely related to the concentration of cortisol in the sample solution. A calibration curve using the relative detected current showed an R2 = 0.98 and CV = 14% for a range of standard cortisol solutions corresponding to the concentrations of native salivary cortisol (0.1 – 10 ng/ml). The measurement could be accomplished within 35 minutes and the cortisol immunosensor could be reused. These results show promise for realizing an on-site and easy-to-use biosensor for cortisol. Used for evaluation of human salivary cortisol levels, the cortisol immunosensor measurement corresponded closely with commercially available ELISA method (R2 = 0.92). Our results indicate the promise of the new cortisol immunosensor for noninvasive, point-of care measurement of human salivary cortisol levels.

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MnO2 nanosheet with acetylene black composite material has been synthesized from layered K0.45MnO2 powder. The electrochemical lithiation reaction of nanosheet composite material proceeds in a different manner from that of the parent material, layered K0.45MnO2 powder. To elucidate the origin of the changes in discharge profile, the electronic and local structures for the nanosheet composites and its parent and protonated material have been investigated by Mn K-edge and O K-edge X-ray absorption spectroscopy (XAS). The results showed that local and electronic structure around Mn ions does not vary during nanosheet formation, while significant changes in electronic structure around oxide ions were observed. Accordingly, it is suggested that the difference observed in discharge profile is due to the electronic structural change induced by nanosheet formation.

In order to improve the cyclability of Sn negative electrode, we tried preparing the Sn film negative electrode by a pulse electrodeposition. Based on the SEM observations, the crystal grains of the Sn film after the pulse electrodeposition were comparatively homogeneous and their grain size was ca. 1 μm. The discharge capacity and the charge-discharge efficiency at the 1st cycle were 679.3 mAh g −1 and 93.0 %, respectively.The charge-discharge tests indicated that the initial electrochemical characteristic of Sn film electrode prepared by a pulse electrodeposition was much better than that of the Sn film electrode prepared by a constant current electrodeposition. The GD-OES profile suggested that Li + ions were easily extracted during the discharge reaction. In addition, it was found that no exfoliation of the film was observed after the 1st discharge though the cracking in the film was observed after the 1st discharge. Consequently, the Sn film electrode prepared by a pulse electrodeposition exhibited a better cyclability for the initial 10 cycles compared to the Sn film electrode prepared by a constant current electrodeposition. By reducing the particle size and repressing the morphological change, the initial electrochemical characteristics were considerably improved. (193 words)

In order to improve the negative electrode characteristics of a graphite electrode in a propylene carbonate (PC) -containing electrolyte, we have prepared a graphite negative electrode coated with a water-soluble anionic polymer as a binder for composite graphite electrodes. The electrochemical characteristics of the coated graphite were evaluated by cyclic voltammetry and charge-discharge cycle tests. The coated graphite negative electrode showed a stable Li + ion intercalation / deintercalation reaction without the exfoliation of the graphene layers caused by the co-intercalation of the PC solvent in the LiClO 4 / PC solution. The charge-discharge characteristic of the coated graphite negative electrode in a PC -containing electrolyte was almost the same as that in ethylene carbonate-based electrolyte.

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