ABSTRACT

Separating cathode material and Al foil from spent lithium-ion batteries (LIBs) is a critical step for LIBs recycling. As compared to chemical dissolving and decomposition, the pyrolysis pretreatment is an alternative and simple method. In this work, the pyrolysis kinetics of cathode material were comparatively studied using various isoconversional methods, including Flynn-Wall-Ozawa (FWO), Friedman, Kissinger-Akahira-Sunose, Starink, Tang, and Boswell. The thermal degradation mechanism was investigated by the Coats-Redfern (CR) and master-plot methods as well. The thermogravimetric analysis revealed that cathode material decomposition could be divided into three stages with mass losses of 1.51%, 0.787%, and 0.449%, respectively. Activation energy (Eα) calculated using the six model-free methods showed a similar trend, gradually increasing as the degree of conversion (α) increased from 0.001 to 0.009, and then significantly elevating. The FWO method gave the best fitting and Eα values first increased from 12.032 to 24.433 kJ·mol⁻¹ with α elevating from 0.001 to 0.009, then increased further to 43.187 kJ·mol⁻¹. Both CR and Criado methods indicated that the degradation of cathode material can be explained by the diffusion models.

Implications: The rapid growth in the production and consumption of lithium-ion batteries (LIBs) for portable electronic devices and electric vehicles has resulted in an increasing number of spent LIBs. Thermal treatment offers advantages of high-efficiency and simple operation. Understanding the thermal process of spent LIBs and probing its kinetic are significant for the large-scale treatment. Through this study, it will be significant for the reactor designing and optimizing in practice.

 抽象的

从废旧锂离子电池（LIB）中分离正极材料和铝箔是锂离子电池回收的关键步骤。与化学溶解和分解相比，热解预处理是一种替代且简单的方法。在这项工作中，使用各种异构转化方法对正极材料的热解动力学进行了比较研究，包括Flynn-Wall-Ozawa (FWO)、Friedman、Kissinger-Akahira-Sunose、Starink、Tang 和Boswell。还通过 Coats-Redfern (CR) 和主图方法研究了热降解机制。热重分析表明，正极材料分解可分为三个阶段，质量损失分别为1.51%、0.787%和0.449%。使用六种无模型方法计算的活化能（E α ）显示出类似的趋势，随着转化度（ α ）从0.001增加到0.009而逐渐增加，然后显着升高。 FWO方法拟合效果最好，Eα值首先从12.032增加到24.433 kJ·mol ^-1 ， α从0.001增加到0.009，然后进一步增加到43.187 kJ·mol ^-1 。 CR 和 Criado 方法均表明正极材料的降解可以通过扩散模型来解释。

影响：便携式电子设备和电动汽车用锂离子电池 (LIB) 生产和消费的快速增长导致废旧锂离子电池数量不断增加。热处理具有效率高、操作简单等优点。了解废锂离子电池的热过程并探究其动力学对于大规模处理具有重要意义。通过本研究，对于反应器的实际设计和优化具有重要意义。