多尺度設計飛彈熱激發電池離子傳輸材料與熱電化學性能

Multi-scale Design of Ionic Transport Materials and Thermo-Electrochemical Performance of Thermal Batteries

陳忠富(Chen, Chung Fu)

指導教授 ： 洪哲文

國立清華大學/工學院/動力機械工程學系/博士(2016年)

摘要

本論文主要以多尺度模擬方法，結合計算量子力學及分子動力學所計算之熔融鹽材料性質與離子傳輸現象，運用計算流體力學方法執行熱電化學性能模擬，進行研究熱啟動電池於不同操作溫度下之熱/質傳分析與電化學性能預測之評估；參考國外文獻所提供之非機密實驗結果，驗證所建立模型與研究方法之正確性與可行性，進而建立一套具多尺度且完整的設計模擬工具，以期能達到開發新式熔融鹽電解質熱電池之性能預測與優化目的。
熱電池又稱為熱激發電池，屬熔融鹽電池的一種，主要特徵為使用之電解質由共晶混合鹽所組成，當外部點火器啟動給予熱源時，透過各單電池的上下熱片傳遞大量熱源，迅速加熱使電解質呈熔融態，並使熱電池開始作電化學反應及放電。本論文首先從熔鹽電解質之二元材料出發，建構微觀尺度模型，利用計算量子力學理論計算原子分布/組成、勢能模型及離子擴散性等，並輔以分子動力學計算離子傳導率、熱傳導率、比熱與熔點等性質；接著運用計算流體力學方法建構巨觀尺度模型及代入微觀尺度模型所計算之性質，求解溫度分布及濃度場，並導入電化學理論，進而探討熱電池放電性能優化分析與評估熱效應造成之影響；另外亦嘗試針對熱電池失效模式(熱崩解及短路)作模擬與預測，探究其可能失效之原因與提出改善建議。
本論文最後提出具備成本低、安全性佳且不易造成環境破壞等優點之LiCl-LiBr-based三元、四元新型電解質材料，並從模擬結果中顯示它們可大幅提升電池性能。此外，四元材料不但可有效降低操作溫度(熔點低)，減少電池失效機率，亦可延長電池作用時間(壽命)。本論文之研究成果，除可有效降低熱電池研發成本，大幅縮減研發時程，並可作為未來研發設計新型熱電池之重要參考依據，從而提升台灣國防科技之競爭力。

關鍵字

多尺度設計 ； 離子傳輸 ； 熔鹽 ； 熱電池 ； 計算量子力學 ； 分子動力學 ； 計算流體力學

並列摘要

The main purpose of this thesis is to set up a multi-scale simulation method which stems from computational quantum mechanics (CQM) to molecular dynamics (MD) to calculate material properties and ionic transport phenomenon. Furthermore, it is integrated with the computational fluid dynamics (CFD) technique to evaluate heat/mass transfer and electrochemical performance of thermal batteries. The simulation results have been compared with experimental data from non-confidential literatures. This is for verifying the correctness and accuracy of the simulation results. The next objective is to establish a multi-scale simulator to design the future novel thermal battery for defense purpose.
Thermal batteries are also named as thermally activated batteries, which employ eutectic salts as their electrolytes, so they are also called molten-salt batteries. At first, we construct a nano-scale model of binary molten-salt electrolytes to perform computational quantum mechanics (CQM) calculations. Secondly, we use molecular dynamics (MD) technique to calculate the ionic conductivity, thermal conductivity, specific heat, and melting point of the material. The CFD technique is then employed to predict the temperature distribution and concentration field in a macro-scale model. Finally, the heat transfer and thermo-electrochemical performance prediction of this battery is carried out. In addition, we also use this package to do the failure analysis (due to thermal runaway and short circuit) of various designs of thermal batteries.
A novel thermal battery, which employs LiCl-LiBr-based ternary and quaternary systems, has been designed using this multiscale simulation package. The results reveal that both the ternary and quaternary materials will enhance the battery performance, also the quaternary ones can reduce the operating temperature that implies quicker start up and longer working life. The multiscale simulation technique provides a low cost alternative to expensive experiments and is able to optimize the battery design under realistic operating conditions for future R&D.

並列關鍵字

multi-scale design ； ionic transport ； molten salt ； thermal batteries ； computational quantum mechanics ； molecular dynamics ； computational fluid dynamics

參考文獻

李皓宇(指導教授 洪哲文)，“熔融電解質熱電池之熱質傳性質與性能分析”，國立清華大學動力機械工程研究所碩士論文，2015年。

R. A. Guidotti, and P. J. Masset, “Thermally activated (thermal) battery technology Part I：An overview,” J. Power Sources, 161, 1443-1449, 2006.

P. J. Masset, and R. A. Guidotti, “Thermally activated (thermal) battery technology Part II：Molten salt electrolytes,” J. Power Sources, 164, 397-414, 2007.

P. Masset, A. Henry, J. Y. Poinso, and J. C. Poignet, “Ionic conductivity measurements of molten iodide–based electrolytes,” J. Power Sources, 160, 752-757, 2006.

P. Masset, “Iodide-based electrolytes: A promising alternative for thermal batteries,” J. Power Sources, 160, 688–697, 2006.