动力电池铝箔的性能衰减机理及工艺改进

摘要

针对动力电池用 A1100 铝箔在室温贮存过程中存在延伸率显著衰减的难题，论文通过力学性能测试、X射线衍射、扫描电镜和热力学计算等手段，对比分析了出厂放置不同时间材料的力学性能和显微组织的变化。结果表明A1100铝箔在室温放置5天后延伸率相比放置2天下降了约 14.5%。进一步的微结构表征和热力学计算分析可知，室温放置过程中，残余应力作用下Si原子扩散加快形成原子偏聚，促进了α-AlFeSi向β-AlFeSi转变及亚结构的粗化。基于所分析的性能衰减机理，提出了加大轧制变形量和提升一级退火温度的工艺优化方案。采用改进工艺，A1100铝箔经室温放置5天后的抗拉强度为 263.8±3.7 MPa (传统工艺：247.8±0.8 MPa)，延伸率为 6.4±0.4% (传统工艺：4.1±0.2 %)，相比传统工艺材料综合性能显著提升。本研究为动力电池铝箔工业生产中的性能一致性与稳定性调控提供了有效的工艺路线。

Abstract

To address the significant decrease in elongation of A1100 aluminum foil for power batteries during room-temperature storage, this study systematically investigates the evolution of mechanical properties and microstructure in materials stored for different durations through mechanical property testing, XRD, SEM, and thermodynamic calculations. The results show that the elongation decreased by approximately 14.5% after 5 days of room-temperature storage compared with that after 2 days. Further microstructural characterization and thermodynamic calculations revealed that residual stress accelerated the diffusion of Si atoms, leading to atomic segregation, and promoted the transformation of α-AlFeSi to β-AlFeSi as well as the coarsening of the substructure during room-temperature storage. An optimized processing route involving an increased rolling reduction and a higher first-stage annealing temperature was proposed based on the identified mechanism of property degradation. The A1100 aluminum foil exhibited a tensile strength of 263.8 ± 3.7 MPa (247.8 ± 0.8 MPa for the conventional process) after 5 days of room-temperature storage, while the elongation reached 6.4 ± 0.4% (4.1 ± 0.2% for the conventional process), it were significantly improved compared with the conventional process. This study provides an effective processing strategy for improving the consistency and stability of the mechanical properties of A1100 aluminum foil during industrial production for power battery applications.