PMMA涂胶隔膜对软包锂离子电池制程及性能影响研究

doi:10.11949/0438-1157.20250994

摘要/Abstract

摘要：

大尺寸软包锂离子电池存在结构变形风险，其常用的聚丙烯（PP）隔膜因易褶皱，可能引发极片黑斑及析锂缺陷。本研究以50 Ah叠片式软包动力电池为载体，系统研究了聚甲基丙烯酸甲酯（PMMA）基涂胶材料对PP基膜在生产制造及电化学性能方面的改进效果。结果表明，PP基膜表面均匀分布的PMMA胶层在有效维持锂离子传输所需多孔结构的同时，显著优化了物性参数。此外，采用PMMA涂胶隔膜的极芯经冷压处理后整体机械强度提高，隔膜与极片贴合紧密，焊接与封装短路率分别从5.37%和0.49%降至0.02%及0%，极片界面和电芯外观显著改善。与基膜组相比，涂胶隔膜组电芯基准容量提升约2.5%，高温放电容量提升约1%–2%，1.0C充电恒流比和1.5C放电容量分别增加约0.6%和1%，常温与高温循环500周后容量保持率分别提升约5%和3.2%。研究结果为下一代高性能锂离子电池的设计与制造提供了新的解决思路。

关键词: 涂胶隔膜, 软包锂离子电池, 冷压, 粘结, 短路率, 电化学, 优化, 设计

Abstract:

Large-sized pouch lithium-ion batteries often encounter structural deformation problems during manufacturing and operation. The commonly used polypropylene (PP) separator, prone to wrinkling, can lead to black spots on electrodes and lithium plating defects. To address these challenges, this study systematically compares the effects of polymethyl methacrylate (PMMA) adhesive-separators and conventional PP separators on the manufacturing process and electrochemical performance of 50 Ah stacked pouch power batteries. Results reveal that the PMMA adhesive layer, uniformly distributed on the PP separator surface, improves the physical and mechanical properties while effectively preserving the porous structure required for lithium-ion transport. In terms of process optimization, batteries utilizing PMMA adhesive-coated separators exhibit enhanced interlayer adhesion strength after cold pressing. Furthermore, the occurrence rates of short circuits during welding and packaging processes are significantly reduced from 5.37% and 0.49% to 0.02% and 0%, respectively. The resulting batteries exhibit a smooth and flat exterior, a design-compliant thickness, and improved electrode interface quality. Electrochemical evaluations demonstrate that batteries with PMMA adhesive-coated separators achieve a 2.5% increase in baseline capacity compared to PP-based counterparts. The constant-current ratio at 1.0C charging rate improves by approximately 0.6%, while discharge capacity ratios at 1.0C and 1.5C rates increase by around 1%. High-temperature discharge capacity improves by 1%-2%. Additionally, After 500 cycles, the capacity retention rates under ambient and elevated temperatures surpass those of PP-based batteries by 5% and 3.2%, respectively. The research results provide new solutions for the design and manufacture of the next generation of high-performance lithium-ion batteries.

Key words: adhesive-separator, pouch lithium-ion battery, cold pressing, adhesion strength, short-circuit rate, electrochemistry, optimization, design

中图分类号:

TM912.9

周晴晴, 项良顺, 国海超, 肖辉, 赵好阳, 姜媛媛, 韦芳芳, 杨东辉, 屠芳芳, 张育红, 相佳媛. PMMA涂胶隔膜对软包锂离子电池制程及性能影响研究[J]. 化工学报, DOI: 10.11949/0438-1157.20250994.

Qingqing Zhou, Liangshun Xiang, Haichao Guo, Hui Xiao, Haoyang Zhao, Yuanyuan Jiang, Fangfang Wei, Donghui Yang, Fangfang Tu, Yuhong Zhang, Jiayuan Xiang. Influence of PMMA Adhesive-Separator on the Manufacturing Process and Performance of Pouch Lithium-ion Battery[J]. CIESC Journal, DOI: 10.11949/0438-1157.20250994.

图/表 11

表1 电池设计参数

Table 1 Design parameters of battery

参数	设计值
参数	正极	负极
面密度/g/m²	380	171
压实密度/g/cm³	2.48	1.55
箔材厚度/µm	12+1+1	4.5
极芯厚度/mm	9.8±0.3
电池厚度/mm	10.8±0.3
单位面积负极容量/正极容量（N/P）	1.15
注液量/g	168±2
设计容量/Ah	50
电池长×宽/mm	252×161

图1 PP隔膜和PMMA涂胶隔膜SEM图

Fig.1 SEM micrographs of PP separator and PMMA adhesive-separator

表2 PP隔膜和涂胶隔膜物性对比

Table 2 Comparison of physical properties of PP separator and adhesive-separator

测试项	PP隔膜	涂胶隔膜
厚度/µm	16	16
透气度/s/100 ml	240	262
接触角/°	54.4°	37.4°
吸液率ρ/%	339.4	808.5
离子电导率σ/10^-4S/cm	2.92	10.73
针刺强度/gf	221	337
MD拉伸强度/kgf/cm²	1650	2011
TD拉伸强度/kgf/cm²	150	154
MD热收缩90 ℃/12 h/%	3.0	0.8
TD热收缩90 ℃/12 h/%	0.2	0
MD热收缩130 ℃/0.5 h/%	3.5	1.0
TD热收缩130 ℃/0.5 h/%	0.15	0

图2 不同冷压条件极芯状态 (a-d); 不同方案极芯封装上料状态 (e-f)

Fig.2 Battery core coil states under different cold pressing conditions (a-d); Battery core packaging status of different schemes (e-f)

表3 8MPa/4 s冷压前后涂胶隔膜的透气值对比

Table 3 Comparison of the air permeability values of the adhesive-separator before and after cold pressing at 8 MPa/4 s

参数	冷压前	冷压后
透气值/s/100 ml	262	267

图3 冷压后负极片与隔膜粘结状态 (a)；冷压后正极片与隔膜粘结状态 (b)；电解液浸润24 h后极芯状态 (c)；极芯冷压前后厚度变化 (d)注:(a) (b) (c) (d)

Fig.3 The bonding state between the negative electrode sheet and the separator after cold pressing (a); The bonding state between the positive electrode sheet and the separator after cold pressing (b); The core wound state (c) after 24 hours of electrolyte immersion; Thickness change of the core before and after cold pressing (d)

表4 电池装配不良对比

Table 4 Comparison of poor battery assembly

参数	PP隔膜	涂胶隔膜
总产出数量/Pcs	10000
焊接前短路数量/Pcs	537	2
焊接前短路率/%	5.37	0.02
封装短路数量/Pcs	49	0
封装短路率/%	0.49	0.00

图4 方案A和方案B电芯外观 (a,b) 和满电极片界面对比 (c,d)

Fig.4 Comparison of the appearance of battery cells (a,b) and the interface of full electrode sheets (c,d) between Scheme A and Scheme B

表5 电化学性能测试数据

Table 5 Test data of electrochemical properties

测试项	方案A		方案B
一步克容量mAh/g	138.5		138.7
三步克容量mAh/g	142.5		142.9
基准容量/Ah	51.8		52.5
倍率充电恒流比/%	0.33C	98.9、99.2	99.0、99.0
	0.5C	98.5、98.6	98.9、99.0
	1.0C	97.2、97.1	97.7、97.8
倍率充电温升/℃	0.33C	1.5、1.9	1.9、2.0
	0.5C	2.4、2.6	2.1、2.2
	1.0C	8.6、8.8	5.7、6.0
倍率放电容量比率/%	0.5C	98.8、98.8	99.1、99.1
	1.0C	96.9、96.6	97.6、97.7
	1.5C	96.6、96.3	97.5、97.3
倍率放电温升/℃	0.5C	3.7、3.7	3.9、3.0
	1.0C	6.5、7.0	7.3、5.6
	1.5C	11.9、12.3	11.0、13.0
55 ℃容量比率/%	101.4、101.4		102.3、103.0
-10 ℃容量比率/%	80.6、87.3		79.6、86.7
60 ℃荷电容量比率/%	96.6、96.5		96.5、96.6
25 ℃荷电容量比率/%	97.0、97.1		97.4、97.8

图5 方案A和方案B电芯基准容量对比

Fig.5 Comparison of Battery Reference Capacity between Scheme A and Scheme B

图6 方案A和方案B电芯倍率充电曲线对比 (a-c)；方案A和方案B电芯倍率放电曲线对比 (d-g)；方案A和方案B电芯不同温度循环性能对比 (h,i)

Fig.6 Comparison of battery rate charging curves between scheme A and B (a-c); Comparison of battery rate discharge curves between scheme A and B (d-g); Comparison of battery cycling performance at different temperatures in scheme A and scheme B (h- i)

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