• Journal of the Korean Electrochemical Society
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• v.25 no.4
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• pp.184-190
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• 2022

Spinel LiMn₂O₄ (LMO) and layered LiNi_0.5Co_0.2Mn_0.3O₂ (NCM) are widely used as positive electrode materials for lithium-ion batteries. LMO and NCM positive electrode materials have a complementary properties. LMO has low cost and high safety and NCM materials show a relatively high specific capacity and better cycle life even at elevated temperature. Therefore, the LMO and NCM active materials are blended and used as a positive electrode in large-size batteries for electric vehicles (xEV). In this study, the cycle performance of a blended electrode prepared by simply mixing LMO and NCM and a bi-layer electrode in which two electrode layers aree sequentially coated are compared. The bi-layer electrode prepared by composing the same ratio of both active materials has similar capacity and cycle performance to the blend electrode. However, the LN electrode coated with LMO first and then NCM is the best in the full cell cycle performance at elevated temperature, and the NL electrode, in which NCM is first coated with LMO has a faster capacity degradation than the blended electrode because LMO is mainly located on the top of the electrode adjacent to electrolyte and graphite negative electrode. Also, the LSTA (linear sweep thermmametry) analysis results show that the LN bi-layer electrode in which the LMO is located inside the electrode has good thermal stability.

• KOREAN JOURNAL OF CROP SCIENCE
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• v.51 no.5
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• pp.432-439
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• 2006

An experiment was conducted to characterize the seed vigour of sweet (su) and super sweet (sh2) corn seeds stored at different temperatures and relative humidities (RH). Hybrid seeds of Early Sunglow ${\times}$ Golden Cross Bantam 70 (su) and Xtrasweet 82 ${\times}$ Fortune (sh2) were stored at different temperatures ($5\;and\;15^{\circ}C$) and RH(70 and 85%) for 10 months. Results of the experiment show that seed deterioration of super sweet corn was much faster than that of sweet corn under all storage conditions. Germination rate of sweet corn seeds at $25^{\circ}C$ and emergence rate in cold test showed similar patterns. Emergence rate of super sweet corn in cold test was significantly lower than the germination rate at $25^{\circ}C$. Germination rate of both sweet and super sweet corns was positively correlated to the emergence rate in cold test, but the correlation coefficient of super sweet corn was much lower compared to the sweet corn. This implies that the viability of super sweet corn seeds should be tested in the cold test to estimate field emergence rate. Seeds of sweet corn could be stored for 5 months under all storage conditions without significant seed deterioration, while those of super sweet corn should be stored at low temperature and RH. The emergence rate of sweet corn in cold test was not correlated to the leakage of total sugars, electrolytes or ${\alpha}-amylase$ activity, while that of super sweet com was positively correlated to the ${\alpha}-amylase$ activity, negatively correlated to the leakage of electrolytes, and was not correlated to the leakage of total sugars.