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Prof. Jang-Uk Choi develops Strong, Long-lasting Lithium-ion Battery Lithium-ion secondary battery with high power, as well asmuch longer life span, has been developed using nanotechnology. Professor Jang-Uk Choi and his colleagues at KAIST University EEWS graduate school has succeeded in developing a new lithium-ion secondary battery that has more than five times the output and three times the life span of the conventional batteries. The industry expects the new battery to significantly improve the acceleration performance and solve the drawbacks of slow electric cars, which occurred due to failure of battery performance to keep up with the output of the motors during acceleration. It is also expected that the new battery could be utilized in various fields that require high power batteries such as Smart Grid, which is the next generation intelligent electrical grid, as well as electric tools and many others. Currently, the most widely used commercial lithium ion batteries’ lithium-cobalt-based cathode material has the disadvantage of expensive cost, high toxicity, short life expectancy and long-charge/discharge time. Also, it has been difficult to apply in electric cars that require a large current density and are vulnerable to heat generated during charging/discharging. On the other hand, Professor Choi and his colleagues’ lithium-manganese based cathode material is gaining popularity for having the advantages such as abundant raw materials, cheap prices, eco-friendliness and especially excellent high-temperature stability and high output, which are suitable for use as electrode material in electric cars. The pure lithium manganese based cathode material has a critical drawback of a very short life expectancy, only lasting about average of 1-2 years, which is due to the elution when the melted manganese flows out into the electrolyte. There have been various studies to solve this problem; however, the unique crystal structure of the material remained as a challenge for many scientists. Professor Choi’s team analyzed the structure of the crystal at the time shortly before manganese oxides were formed, while controlling the reaction temperature at the step of synthesizing nanomaterial. It has been found that, at 220℃, there are simultaneously existing two crystal faces, one that inhibits the dissolution of manganese ions and the other that enables lithium ions to move smoothly. Each of these crystal faces improves both the life span and output, increasing the output more than five times and life expectancy over three times. In addition, the existing high temperature life span, that was known to be especially vulnerable, has improved ten-fold. “By controlling the crystal face of lithium manganese anode material, which has previously existed in the battery as chunks of about 10 micro-meter particles, both output and life span has significantly improved,” said Professor Choi, “Domestic and international patent application for the regarding technology has been finished and we have plans to work with companies in the future for commercialization within 2-3 years.” Professor Yi Cui of Stanford University, the world’s leading scholar on the secondary battery, has evaluated that “This research exemplifies how nanotechnology can innovatively develop the field of secondary battery.” Meanwhile, the research led by Professor Jang-Uk Choi and participated by researcher Ju-Seong Kim has been published on the online edition (dated Nov 27th) of Nanoletters, the world’s leading authority on Nanoscience.
2012.12.21 View 8769

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