The proposed system is highly accurate and reliable for measuring the severity of skin pore enlargement. It can be suitably used for objective assessment of the pore tightening treatments.

Surface morphological changes of Li powder compacted electrodes were investigated and compared with extruded Li foil electrodes during the dissolution (discharge)/deposition (charge) process. The area of derlclrite growing surfaces was reduced remarkably for Li powder compacted electrodes. Impedance measurements showed that Li compacted powder electrodes had a lower resistance than Li foil electrodes. This is presumed to be related with resistance reduction due to increasing ion conductivity in the SEI (solid electrolyte interface) formed on the surface along with the increase of the reaction area for the powder electrode.Keywords : lithium, battery, SEI, impedance, lithium metal battery, lithium powder I N T R O D U C T I O NAlthough pure Li metal has remarkable electrochemical characteristics of not only increasing the capacity but also reducing the weight of secondary batteries, carbon is used instead as anode active material for Li-ion batteries. This is mainly due to the cycling efficiency deterioration and safety problem caused by dendrite growth during the deposition (charge) which limits its application [1][2][3]. Some parts of deposited Li are isolated from newly formed surface films [1,2]. Such isolated Li, called dead Li, is electrically separated from Li metal substrate, and cannot participate in the electrochemical reaction [1,2]. It results in capacity loss, and reduces the cycling efficiency. Moreover, Li dendrites may pierce the separator and cause short circuits in batteries [3].The most popular model for the interface between Li metal and nonaqueous electrolytes, proposed by Peled, is called the solid electrolyte interface (SEI) model [4]. In the SEI model, the surface film can affect the morphology of the electrodeposited Li because Li metal is deposited via migration of Li § ions through the SEI film. The SEI films are known to be composed of various lithium compounds such as LiOH, Li20, and Li2CO3 [5], and therefore the as-formed SEI film has heterogeneous compositions. In the case of a rechargeable battery, the charging current distribution in such an SEI film is localized and causes dendritic growth [3].Dendritic growth of deposited Li causes the worst problem in metal rechargeable batteries; for this reason much research has been done on the prevention of Li dendrite growth. It has been said that Li dendrite growth is restrained when SEI is stable, thin, smooth and homogeneous [3]. This condition can be brought about by surface control using various additives such as CO2, HE surfactants, etc. [3,[6][7].In this paper, compacted Li powders that were made in the lab were introduced for the Li metal battery anode and the results were compared with those of conventionally extruded Li foil. Half-cell tests were performed on both the powders and the foils to observe the mechanism of Li dendrite growth. The changes o f the surface morphology of Li were investigated through an optical microscope. Impedance measurement of the powders and the foil specimen were also done. EXPERIMENTALSTo find Li den...

Stabilities of Ca-alginatc fiber and ACP(Alginate + Cclitc R-634 + Pectin) gel fibers containing different concentrations of alginatc w'crc tested. The results showed that the stability of ACP gel fiber containing 5% alginate(5% ACP gel fiber) was better than those of other fibers tested, considering the degree of release of yeast from gel fiber. Scanning electron microscopic observation proved the above results, and concentrations of ccl1 and ethanol obtained by 5% ACP gel fiber \vere higher than those of others, respectively.