報告書番号

W03029

タイトル（和文）

MCFC寿命予測手法の開発 -性能表示式と電解質量との関係解明-

タイトル（英文）

Development of estimation method for MCFC life time Modification of reaction resistance model based on the electrolyte content

概要 （図表や脚注は「報告書全文」に掲載しております）

MCFCのセル電圧は、電池内電解質が主に腐食によって損耗するため、時間経過とともに徐々に低下する。国は４万時間運転後のセル電圧低下を初期セル電圧の１割以下に抑制することを開発目標としているが、この実証には長期を要するため、初期運転データを基に４万時間運転後のセル電圧を予測することができれば電池改良を効率的に行うことが可能となる。そこで、MCFCの４万時間運転後の単セル電圧を予測するため、電解質量の時間依存性を表す式を提案した。次に、電解質組成（Li/K、Li/Na）や温度を種々の条件に設定し実測されたデータから反応面積を算出する方法を確立した。さらに、運転開始時の反応面積で除し規格化した反応面積は、推算電解質量に比例することを明らかにし、実験せずに推算電解質量のみから性能表示式係数を決定することが可能となった。推算電解質量の時間依存性を基に、性能表示式の係数を求めセル電圧を予測した結果、電解質組成等の条件を問わず実測値を5mV程度の誤差で良く再現でき、４万時間運転後のセル電圧の予測が初めて可能となった。

概要 （英文）

Cell voltage of Molten Carbonate Fuel Cell (MCFC) decreases with operating time since the electrolyte is consumed mainly by corrosion of separator plates. In the Japanese national project, the target of cell voltage decreasing rate is lower than 10% of initial cell voltage at 40000 h in operating time. However, it takes much time to demonstrate that MCFC keeps its cell voltage at higher than 90% of initial cell voltage. If cell voltage at 40000 h is able to be estimated from initial cell voltage, improvement of cell material or design is achieved in short time. Therefore, cell lifetime estimation method has been developed.At first, an estimation equation of the electrolyte content in the cell with time, has been derived. The electrolyte content estimated by the equation approximately agrees with the value calculated from measured internal resistance. Subsequently, reaction areas of gas and liquid phases were determined using the anode and cathode reaction resistance models and physical properties. Standardized reaction area divided by initial reaction area is proportional to the electrolyte content. As a result, parameters in the anode and cathode reaction resistance models are able to be determined by the electrolyte content and physical properties. Time dependency of parameters in the resistance models are calculated by physical properties and the electrolyte content change with time. Cell voltage change with time is calculated using time dependency of parameters in resistance models. Consequently, cell voltages estimated by this cell lifetime estimation method agree with measured cell voltages. It is conformed that their voltage difference is lower than 5 mV and cell lifetime estimation method has good accuracy for cell voltage estimation for 40000 h.

報告者

キーワード