LiCoO2/人造石墨全電池在高電壓與高溫下之研究

因應能源需求及電子產品的開發，對鋰電池中鋰離子容量的要求，只升不降，因此對於鋰離子二次電池體系運用之電壓之要求隨之增高。然而，隨著電壓(>4.2V)的提升，會導致正極材料結構不穩定而造成放熱反應，而造成安全疑慮∘故，尋找能承受高壓高溫之正極材料，在產業中成為一急需解決的課題。本研究係利用物理納米化及化學沉積表面包覆兩種方法合成之正極LiCoO2材料，分別與人造石墨組成的全電池，就材料在高電壓與高溫下充、放電行為變化之差異，進行一系列之研究。研究結果顯示，利用化學沉積包覆之B型正極材料較物理納米化之A型正極材料佳，除已突破目前商業化充電上限55℃的要求，並在60℃環境下以1C速率連續充放電300圈後，電容量仍能保持>84%之水準。此外，在4.4V 飽電及70℃下之環境下靜置15天，此電池之產氣量尚可管控在10%以下。此研究證實，化學沉積物包覆B型正極材料所使用之表面包覆方法為一有效之技術，用在電池中明顯改善其效能，而其原因則歸於電解液與正極兼容性的改善∘

關鍵字

鋰電池；高電壓

並列摘要

In response to the demand of energy and electronic product development, increasing the lithium ion capacity is highly required, leading to the pursuit of high voltage lithium-ion battery system. However, under the high voltage performance, the instability of cathode material structure is resulted due to the occurrence of the exothermic reactions, resulting in the security concerns. Therefore, looking for a high-voltage high- temperature stable cathode material has become an urgent need in industry. To meet the need, in this study, the investigation and comparison of a series of the lithium batteries, composed with a Artificial graphite as the negative electrode and two kinds of LiCoO2, synthesized by physical nano-crystallization method and chemical deposition coating method, respectively, as the positive electrode material were conducted. The results showed that the charge and discharge behavior of the two LiCoO2 positive materials are different. The results of the study indicated that the batteries fabricated with the coated LiCoO2 (B-type cathode material) showed better efficiency. It demonstrated a higher charging temperature limit than the current commercial charging temperature limit of 55 ℃. Besides, at 60 ℃, after 300 times of continuous charge and discharge with 1C rate, the capacity can still maintain> 84% of the standard. Furthermore, under the environment of the saturated voltage (4.4V) and 70℃ for 15 days, the percentage of the battery swelling produced was controlled below 10%. This study confirmed that the surface coating method used by the chemical deposition method to cover the B-type positive electrode material is an effective technique that significantly improved the effectiveness in the lithium battery, and is ascribed to the improvements in the compatibility between the electrolyte and the positive material.

並列關鍵字

lithium-ion battery ； high voltage

參考文獻

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LiCoO2/人造石墨全電池在高電壓與高溫下之研究

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