應用 PyBaMM 之偽二維模型評估鋰鍍覆反應

Abstract

鋰離子電池在儲能應用中佔有重要地位，然而在低溫或快速充電條件下，容易發生鋰鍍覆反應 (即鋰金屬沉積)，進而導致容量衰退與短路風險增加。因此，了鋰鍍覆機制及其安全操作區域，對於設計兼具效率與安全性的充電策略至關重要。 本研究基於 PyBaMM 電池模擬平台，建構具備鋰鍍覆反應計算能力之 P2D電化學模型，並以過電位變化作為鋰鍍覆與剝離行為轉換的判斷依據，定義過電位轉為負值之時間點為鋰鍍覆反應啟動的臨界時間點。研究針對不同充電倍率（C-rate）與溫度條件，分別分析兩段時間區間：其一為充電至商用電池電壓上限4.2 V 的「全程充電階段」，其二為「鋰鍍覆發生前充電階段」。 分析結果顯示，鋰鍍覆量並非單純隨溫度降低及充電速率提高而增加，而是會受到截止電壓限制的影響，在低溫高倍率條件下，由於系統過早達到截止電壓，鋰鍍覆無足夠時間持續發生，因而呈現非線性的變化趨勢。在−10◦C / 0.2 C至 25◦C / 1.0 C 以上形成無鋰鍍覆的操作區域，為安全充電範圍。鋰鍍覆最嚴重的條件出現在 −10◦C / 1.8 C，鍍覆量佔比最高。在效率評估中，25◦C / 1.2 C 為一小時內充至 SOC 50%，的效率最佳條件；相對地，−10◦C / 1.8 C 為效率最低條件。 綜上所述，本研究透過電化學模型模擬結果建立了一套評估鋰鍍覆反應發生區域及其嚴重度的方法，可以作為未來充電策略設計的參考。

Lithium-ion batteries play a crucial role in energy storage applications. However, under low-temperature or fast-charging conditions, they are prone to lithium metal deposition (i.e., lithium plating), which leads to capacity degradation and increased risk of internal short circuits. Understanding the mechanism of lithium plating and identifying its safe operating region is essential for developing charging strategies that balance efficiency and safety. In this study, a pseudo-two-dimensional (P2D) electrochemical model incorporating lithium plating reactions was developed based on the PyBaMM simulation platform. The model uses overpotential behavior to determine the onset and reversal of lithium plating and stripping. The onset of lithium plating is defined as the moment when the overpotential becomes negative. Two time intervals were analyzed under various C-rates and temperature conditions: (1) the full charging stage, defined as the charging period up to the commercial voltage limit of 4.2 V, and (2) the pre-plating charging stage, defined as the charging duration before lithium plating begins. The analysis shows that the amount of lithium plating does not simply increase with lower temperatures and higher charging rates, but is instead affected by the cutoff voltage.Under low-temperature and high-rate conditions, the system reaches the cutoff voltage prematurely, leaving insufficient time for continuous lithium plating, resulting in a nonlinear plating trend. An operating range from −10 ◦C / 0.2 C to 25 ◦C / 1.0 C and above forms a safe charging window with virtually no lithium plating. The most severe plating occurs at −10 ◦C / 1.8 C, where the proportion of plated lithium reaches its maximum. In terms of efficiency evaluation, 25 ◦C / 1.2 C is identified as the optimal condition, achieving 50% SOC within one hour, whereas −10 ◦C / 1.8 C shows the lowest efficiency. In summary, this study used electrochemical model simulations to establish a method for evaluating the occurrence and severity of lithium plating. These results can serve as a reference for future charging strategy design.