Closed-loop control strategy of mass-density flow field evolution and film morphology for slot die coating

doi:10.19799/j.cnki.2095-4239.2024.0025

Abstract

Abstract:

As a key process in manufacturing lithium-ion batteries, coating compliance with process specifications plays a crucial role in the capacity consistency and safety of batteries and involves complex mechanisms such as surface chemistry and rheology theory. Lithium-ion battery manufacturers and coating equipment suppliers are pursuing automated and intelligent coating operation methods, whereas current research on coating is often limited to surface chemistry and other microscopic problems. Based on comprehensive literature research and simulation analysis, four evolution processes of mass-density flow field and film morphology of slurry, namely during slot die coating, mold expansion, wetting film formation, and drying shrinkage, are proposed for the first time. The influence of six key processes and quality indices, namely the consistency of the transverse opposite density, consistency of longitudinal areal density, edge thickness, film width, missing coating defects, and peel strength after calendaring, are summarized in the process of coating evolution. Through the analysis of these active variables and uncontrollable factors affecting the coating process, we can better understand the possible problems and reasons related to these problems in the coating process. Finally, a closed-loop control strategy combining intelligence and manual intervention was devised to manage the six coating quality indices. This strategy provides theoretical guidance and an algorithmic framework for improving intelligent coating and unmanned production. Additionally, this strategy is of great significance for improving the quality and production efficiency of lithium-ion battery coatings.

Key words: slot die coating, surface chemistry, rheology, manufacturing process, intelligent manufacturing

CLC Number:

TQ 586.3

Yuqing LIU, Huaifeng LIN, Yanling YU, Dong CUI. Closed-loop control strategy of mass-density flow field evolution and film morphology for slot die coating[J]. Energy Storage Science and Technology, 2024, 13(4): 1118-1127.

Figures/Tables 14

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因素分类	详细因素	面密度横向一致性	面密度纵向一致性	边缘厚度	膜区宽度	漏涂缺陷	辊压后剥离强度
浆料特性	黏度	√		√
	弹性				√
	粒度					√
	表面张力			√	√	√

成膜能力	设计膜区厚度					√
成膜能力	基材表面能					√

供料系统	缓存罐液位差	√	√
	螺杆泵磨损	√	√
	滤芯堵塞	√	√

模头系统	腔体数量/形状	√
	腔体压条	√
	唇口阻流块	√
	唇口变形推拉杆	√
	垫片厚度	√				√
	垫片流道宽度				√
	垫片开角			√

唇口与背辊空间	模头唇口水平度	√				√
	模头间隙	√		√	√	√
	背辊圆跳动	√	√

烘箱系统	烘箱温度			√			√
烘箱系统	烘烤风速			√			√

因素分类	详细因素	能否智能监测	能否智能控制
浆料特性	黏度	流变仪	被动变量
	弹性	流变仪
	粒度	人工测量
	表面张力	人工测量
成膜能力	设计膜区厚度	面密度测重仪
成膜能力	基材表面能	人工测量

供料系统	缓存罐液位差	上料压力波动监控	可智能(泵速调节)
	螺杆泵磨损
	滤芯堵塞

模头系统	腔体数量/形状	人工设计	被动变量
	腔体压条	人工测量	人工更换(需停机)
	唇口阻流块	位移传感器	可智能(阻流块位移)
	唇口变形推拉杆	人工测量	人工调节(无需停机)
	垫片	人工测量	人工更换(需停机)

唇口与背辊空间	模头唇口水平度	人工测量	人工修复(需停机)
	模头间隙	位移传感器	可智能(进退模头)
	背辊圆跳动	人工测量	人工修复(需停机)

烘箱系统	烘箱温度	温度传感器	可智能(温度调节)
烘箱系统	烘烤风速	风速仪	可智能(风速调节)

质量问题	监测工具	湿膜监测时延	干膜监测时延	调节策略数量	智能化调节策略数量	优先级
面密度横向一致性	面密度仪	实时	涂布烘烤时间	9	3	低
面密度纵向一致性	面密度仪	实时	涂布烘烤时间	2	1	高
边缘厚度	激光测厚仪	实时	涂布烘烤时间	4	3	低
膜区宽度	机器视觉	实时	涂布烘烤时间	1	1	高
漏涂缺陷	机器视觉	实时	涂布烘烤时间	3	1	中
辊压后剥离强度	拉力机	无法监测	涂布烘烤时间+辊压时间+等待时间	2	2	中

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