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標題: | 新的電化學參數評估法用於循環老化後的鋰離子電池 A novel evaluation of electrochemical parameters for cycle aged lithium-ion batteries |
作者: | Jin-Hao Yang 楊晉豪 |
指導教授: | 陳國慶(Kuo-Ching Chen) |
關鍵字: | 鋰離子電池,循環老化,dQ/dV圖形,老化機制,電化學參數, Lithium-ion battery,cycle aging,dQ/dV pattern,aging mechanism,electrochemical parameters, |
出版年 : | 2020 |
學位: | 碩士 |
摘要: | 由於鋰離子電池的電化學參數過於繁雜,並且會隨著電池的老化而改變,目前推測電池老化的方式都是由電化學模型再附加一個老化模型進行模擬。而在本研究中,將提出一些全新的方法對使用過後的鋰離子電池之電化學參數進行評估。從實驗結果得知,電池在充放電過程中電荷(Q)-電壓(V)圖形的一階導數dQ/dV圖形峰值之偏移量,會隨著電池的老化而有所改變。因此,透過dQ/dV圖形峰值的偏移量,進而得到電化學參數隨老化改變的資訊。 首先LCO電池的部分,使用全新電池經小電流放電後的電荷(Q)-電壓(V)圖形為依據,調整大部分的參數使模擬的電荷(Q)-電壓(V)圖形與實驗吻合,取得全新LCO電池所有的電化學參數。由文獻中的實驗結果得知,LCO電池使用時正極活性材料表面並不會有明顯的改變。因此,歸納出負極鋰離子初始濃度(Cs_neg)及負極顆粒體積分率(εs_neg)兩個電化學參數為主導鋰鈷氧電池老化的主要參數,並改變這兩個電化學參數進行模擬,取得電化學參數與dQ/dV圖形峰值偏移量的關係,建立資料庫。經由循環老化實驗取得電池老化後dQ/dV圖形峰值偏移量,查詢模擬所建立之資料庫,便能得到電池老化後的電化學參數,再進一步建立電化學參數與電池容量之間的比例關係,最後比較藉由電化學參數推出的容量與實驗測得的容量進行驗證。 本研究對主導LFP電池老化的電化學參數進行評估,藉由dQ/dV圖形提供更多的資訊,歸納出LFP電池在老化前期由負極鋰離子初始濃度(Cs_neg)、負極顆粒體積分率(εs_neg)、正極粒子半徑(rp_pos)為主要變動的電化學參數。LFP電池在老化後期則為負極擴散係數(Ds_neg)所主導。再實際對LFP電池進行實驗,並與文獻實驗結果比較,發現LFP電池若是要有較精準的dQ/dV圖形測試電流必需很小,溫度的誤差不能過大。 利用NCA電池的電化學老化模型,透過dQ/dV圖形的比較,驗證文獻中Alawa tool的模擬結果,發現dQ/dV圖形中的Peak 1偏移是受到電極活性材料損失的影響。最後,NMC電池的部分,本研究透過調整負極鋰離子初始濃度(Cs_neg)、負極顆粒體積分率(εs_neg)、正極顆粒體積分率(εs_pos),觀察dQ/dV圖形中峰值的變化,提出一套求解電化學參數的流程。 Because the electrochemical parameters of lithium-ion batteries are too complicated, and it will change as the battery ages. At present, it is speculated that the way of battery aging is simulated by the electrochemical aging model. This study will propose some new methods to evaluate the electrochemical parameters of used lithium-ion batteries. From the experimental results, it is known that the dQ/dV pattern peak shift obtained by extending the capacity (Q)-voltage (V) pattern during charging and discharging of the battery will change as the battery ages. Therefore, the information about the change of electrochemical parameters with the aging of the battery can be obtained through the shift of the peak value of the dQ/dV pattern. First of all, according to the capacity (Q)-voltage (V) graph of the new battery after a small current discharge, adjust most of the electrochemical parameters to make the simulation fit the capacity (Q)-voltage (V) graph of the experiment, so all the electrochemical parameters of the new LCO battery are obtained. It is known from experiments in the literature that the surface of the positive electrode active material does not change significantly when the LCO battery is used. Therefore, it is concluded that Cs_neg and εs_neg are the electrochemical parameters that dominate the aging of LCO batteries, and the two electrochemical parameters are changed for simulation to obtain the relationship between the electrochemical parameters and the dQ/dV graph peak offset and establish a database. Through the cycle aging experiment, the dQ/dV graph peak offset after battery aging is obtained. Querying the database can obtain the electrochemical parameters after battery aging, and then establish the proportional relationship between the electrochemical parameters and the battery capacity. Finally, compare the simulation and experimental capacity to verify. In this study, the electrochemical parameters of LFP batteries after aging were evaluated. Through dQ/dV graph to provide more information, it is concluded that the dominant electrochemical parameters of LFP battery in the linear aging stage are Cs_neg, εs_neg and rp_pos. In the non-linear aging stage of the LFP battery, the electrochemical parameter that dominates the aging of the LFP battery is Ds_neg. By comparing the experimental results of the LFP battery with the experimental results in the literature, it is found that if the LFP battery is to measure a more accurate dQ/dV pattern, the current must be very small, and the temperature deviation cannot be too large. Using the electrochemical aging model of NCA battery, through the comparison of dQ/dV graphics, the simulation results of Alawa tool in the literature were further verified. It is found that the Peak 1 shift in the dQ/dV pattern is affected by the loss of electrode active material. At the end of the NMC battery, this study adjusts Cs_neg, εs_neg, εs_pos to observe the change of the peak value in the dQ/dV graph, and proposes a set of procedures for solving the electrochemical parameters. |
URI: | http://tdr.lib.ntu.edu.tw/jspui/handle/123456789/68538 |
DOI: | 10.6342/NTU202003717 |
全文授權: | 有償授權 |
顯示於系所單位: | 應用力學研究所 |
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