Life Prediction Modeling of Lithium-Ion Batteries based on Electrochemical Analysis

鋰電池因具有高能量密度、良好的穩定度、充放電效率高、循環壽命長等優點，已成為電動車儲能裝置的主流，但國內、外鮮少見到鋰電池量化可靠度的研究。本研究第一部份使用電化學原理建立鋰電池分析模型，得出負載電流與電池輸出電壓間的關係，藉以瞭解固定的電流下電池額定電壓至截止電壓的時間，並求出電池額定電量。以上額定電量並不隨充放電次數而改變，與真實情況不符，故本研究第二部份根據鋰電池衰退機制，考量負電極固態電解質界面膜的成長量，建立鋰電池電量衰退模型。研究第三部份則考量鋰電池充電後額定電量降低至百分之八十的失效情境，將文獻所載一車輛每日行駛距離分佈，轉換成每次隨機放電深度分佈，而後代入鋰電池電量衰退模型中，得出電池壽命分佈及其它可靠度指標。本研究特別呈現三種特定情境下，鋰電池的量化可靠度及相關指標。The lithium-ion battery has been considered a good candidate for use in electric vehicle energy storage devices owing to its stability, high–power density, and high cycle–life. However, there are few studies about the quantitative reliability of lithium-ion battery. Therefore, in this study, a quantitative reliability analysis for lithium-ion battery is carried out. The study consists of three parts. First, mathematical model is established based on electrochemical theorem. Secondly, the capacity fading is examined by focusing on the growth of solid electrolyte at the Negative electrode, which is considered the canonical degradation mechanism of the battery. It is shown that a simple single-particle model is enough to explain experimentally observed capacity fading of a battery with negative electrode. The third part of this study focuses on the reliability estimation of lithium-ion battery. The un-reliability or failure condition is defined as when a battery’s capacity after recharging drops to 80% of its nominal capacity. When considering the usage situation, the distribution of driving distance per day of a vehicle is transformed into the depth of discharge and also randomized. The mean and standard deviation of life and quantitative reliability of the battery are estimated accordingly. Three different environmental and usage situations are considered in particular