基于相场模型的锂电池电极浆料稳定涂布窗口分析

doi:10.19799/j.cnki.2095-4239.2023.0300

摘要/Abstract

摘要：

极片涂布是锂离子电池极片制造的关键工艺之一，涂布质量决定了极片结构的均匀度，进而影响电池的性能和寿命。针对电极浆料涂布质量控制问题，选取狭缝涂布模头和集流体组成的局部区域为研究对象，建立了相场-流场耦合的多物理场模型。基于该模型模拟了电极浆料的流动以及电极涂层形成，并根据涂布质量确定了稳定的涂布窗口，通过与实验结果的对比验证了仿真模型的可靠性。以拓宽涂布窗口、实现高速稳定涂布为目标对涂布模头的主要尺寸进行优化。结果表明，浆料流量过大或过小将导致气泡混入或上游溢出，涂布过程无法达到稳定；模头的主要几何尺寸对稳定涂布窗口有一定影响，但仅通过对其简单增减无法将涂布窗口拓宽；对上游模头、下游模头进行非对称式调整，改变上下游流动阻力的相对大小，可以将浆料流量上限提高约40%。通过数值模拟对狭缝涂布过程中的浆料流动进行了分析，为锂电池电极浆料涂布工艺参数的优化提供了参考。

关键词: 锂离子电池, 制造工艺, 电极浆料, 狭缝涂布, 数值模拟

Abstract:

Electrode coating is one of the key processes in the manufacturing of lithium-ion battery electrodes. The coating quality determines the uniformity of the electrode structure, which in turn affects the performance and lifespan of the battery. In response to the quality control problem of electrode slurry slot die coating, this study selects a local area composed of the slot die and the fluid collector as the research object and establishes a multiphysics field model coupled with phase field and flow field. Based on this model, the slurry flow during the slit coating process was analyzed through numerical simulation, providing a reference for optimizing the coating process parameters of lithium battery electrode slurry. Similarly, a stable coating window was determined based on the coating quality. The reliability of the simulation model was verified by comparing it with experimental results. We optimized the main dimensions of the coating die with the goal of expanding the coating window and achieving high-speed and stable coating. The results indicated that excessive or insufficient slurry flow rate will cause bubbles to mix in or overflow upstream, making the coating process unstable. The main geometric dimensions of the slot die had a specific impact on the stable coating window; however, simply increasing or decreasing the geometric dimensions cannot broaden the coating window. Asymmetric adjustment of the upstream and downstream die heads could increase the upper limit of slurry flow by 40% by changing the relative magnitude of upstream and downstream flow resistance.

Key words: lithium ion battery, manufacturing process, electrode slurry, slot die coating, numerical simulation

中图分类号:

TQ 024.1

陈育新, 杨家沐, 练成, 刘洪来. 基于相场模型的锂电池电极浆料稳定涂布窗口分析[J]. 储能科学与技术, 2023, 12(7): 2185-2193.

Yuxin CHEN, Jiamu YANG, Cheng LIAN, Honglai LIU. Analysis of stable coating window of lithium battery electrode paste based on phase field models[J]. Energy Storage Science and Technology, 2023, 12(7): 2185-2193.

图/表 12

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图9

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参数	数值
狭缝宽度W/mm	0.3，0.5，0.7
模唇宽度L/mm	0.8，1.0，1.5
模头高度H/mm	0.15，0.2，0.3
模头倾角 β /(°)	45
浆料密度 ρ_l/(kg/m³)	1320
浆料表面张力 σ /(N/m)	0.066
浆料黏度 μ_l/(Pa∙s)	式(1)
参考剪切速率 γ_ref/s^-1	1
流体一致性系数M/(Pa∙s)	3.585
流动特性指数N	0.6322
浆料-模头接触角 θ₁/(°)	72.5
浆料-集流体接触角 θ₂/(°)	55.6
空气密度 ρ_g/(kg/m³)	1.2
空气黏度 μ_g/(mPa∙s)	0.02

分组	调整的模头尺寸	数值
H1-1	模头高度H/mm	0.3
H1-2	模头高度H/mm	0.15
W1-1	狭缝宽度W/mm	0.7
W1-2	狭缝宽度W/mm	0.3
L1-1	模唇宽度L/mm	1.5
L1-2	模唇宽度L/mm	0.8

分组	调整的模头尺寸	数值
L2-1	上游模唇宽度L_u/mm	1.5
L2-1	下游模唇宽度L_d/mm	0.8
L2-2	上游模唇宽度L_u/mm	0.8
L2-2	下游模唇宽度L_d/mm	1.5
H2-1	上游模头高度H_u/mm	0.3
H2-1	下游模头高度H_d/mm	0.15
H2-2	上游模头高度H_u/mm	0.15
H2-2	下游模头高度H_d/mm	0.3

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