| Summary: | 碩士 === 逢甲大學 === 材料科學所 === 92 === Abstract
Secondary lithium batteries have been the primary power supply components for various portable electronic devices, such as cell phones and notebook computers. However, as the weight and volume of the portable devices continuously decrease, the search for smaller, lighter, and higher-power-density sources has never stopped. In order to meet these requirements, the concept of Thin Film Batteries (TFB), or all solid state micro-batteries, has therefore been of great interest. With only a few micron meters of thickness or less, thin film batteries are compatible with micron electro-mechanical devices, and can be the back-up power for SRAM, as well.
This research uses LiMn2O4 as cathode material of thin film batteries. The applied substrate bias during sputtering of LixMn2-yO4 thin film will control the ion-bombarding energy and achieve the in-situ modification. Moreover, the air annealing will improve the properties of LixMn2-yO4 thin film, such as the capacity, discharge voltage and electric conductivity. The result shows that bias -20VDC will deposit LixMn2-yO4 film with some appropriate defects. These defects are expected to provide a flexible space which can help to maintain the spinel structure. These films have better cycle life and their discharge capacity can reach 122 mAh/g. The 600℃-1hr air annealing can increase effectively the characteristic of 0VDC deposited LixMn2-yO4 films. These air-annealed films can have a perfect spinel structure and exhibit a two-stage discharge voltage plate（4.1 and 3.9V）.
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