Microstructure and rheology of microporous layer ink for proton exchange membrane fuel cells

doi:10.16085/j.issn.1000-6613.2021-1856

Abstract

Abstract:

The microporous layer (MPL) is an important component of water management in proton exchange membrane fuel cells (PEMFC). It is crucial to gain an in-depth understanding of MPL ink, which determines MPL's structure and performance. In this paper, four typical carbon blacks [ACET, XC-72R, BP2000, and natural gas cracking carbon black (NG)] were selected to systematically study the microstructure of the slurry by using atomic force microscopy (AFM), field emission transmission electron microscopy (TEM) and dynamic light scattering particle size analyzer (DLS PSD). Agglomeration was proposed as an ink evaluation criterion, and quantitative criteria were also given by combining rheology study. The results showed that the agglomeration degree of different carbon blacks was in the following order: ACET>XC-72R>BP2000>NG. The larger the shear thinning index n, the lower the agglomeration degree of MPL slurry and the more uniform the particle dispersion, and the smaller the n, the higher the agglomeration degree. Specifically, for the solid content α=6%, n_NG-MPL=0.554, n_BP2000-MPL=0.320, n_XC-72R-MPL=0.118, and n_ACET-MPL=0.039. The measured agglomerates particle sizes of ACET, XC-72R, BP2000 and NG were 1.358μm, 1.149μm, 0.732μm and 0.406μm, respectively. So the shear thinning index of the ink should be inversely proportional to the degree of agglomeration. In conclusion, NG-MPL has the lowest shear thinning degree and is a more suitable carbon material for MPL, which also provides guidance for the preparation and optimization of MPL in the future.

Key words: fuel cell, microporous layer, carbon black, microstructure, rheology

摘要：

微孔层（MPL）是质子交换膜燃料电池（PEMFC）水管理的重要部件。本文系统性选择了4种典型炭黑[ACET、XC-72R、BP2000、天然气裂解炭黑（NG）]，借助原子力显微镜（AFM）、场发射透射电镜（TEM）和动态光散射粒度分析仪（DLS PSD）对浆液微观结构的研究，给出团聚性这一浆液评价标准，并结合流变性揭示了定量标准。研究结果表明，不同炭黑的团聚程度大小依次为ACET>XC-72R>BP2000>NG。剪切稀化指数n越大，MPL浆液团聚程度越低，颗粒分散越均匀；n越小，团聚程度越高。具体而言，固含量α=6%时，添加NG、BP2000、XC-72R、ACET炭黑的MPL浆液的剪切稀化指数n分别为0.554、0.320、0.118、0.039；测得的ACET、XC-72R、BP2000、NG的团聚体粒径分别为1.358μm、1.149μm、0.732μm、0.406μm，所以浆液的剪切稀化指数与其团聚程度成反比。总之，NG-MPL剪切稀化程度最低，NG更加适合作为MPL的碳材料，也为今后MPL的制备和优化提供指导。

关键词: 燃料电池, 微孔层, 炭黑, 微观结构, 流变性

CLC Number:

CHEN Zhekun, PAN Weitong, YAO Dingsong, DING Lu, WANG Fuchen. Microstructure and rheology of microporous layer ink for proton exchange membrane fuel cells[J]. Chemical Industry and Engineering Progress, 2022, 41(7): 3808-3815.

陈哲坤, 潘伟童, 姚顶松, 丁路, 王辅臣. 质子交换膜燃料电池微孔层浆液微观结构与流变性[J]. 化工进展, 2022, 41(7): 3808-3815.

Figures/Tables 8

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炭黑类型	V_总孔/m³·g^－1	V_{介孔+大孔}/ m³·g^－1	V_微孔/m³·g^－1
ACET	0.168	0.167	0.001
XC-72R	0.441	0.410	0.031
NG	0.951	0.941	0.010

炭黑类型	V_总孔/m³·g^－1	V_{介孔+大孔}/ m³·g^－1	V_微孔/m³·g^－1
ACET	0.168	0.167	0.001
XC-72R	0.441	0.410	0.031
NG	0.951	0.941	0.010

炭黑类型	平均粒径/nm	多分散性指数
ACET	443.6	0.403
XC-72R	374.3	0.062
NG	209.5	0.040

炭黑类型	平均粒径/nm	多分散性指数
ACET	443.6	0.403
XC-72R	374.3	0.062
NG	209.5	0.040

炭黑类型	α/%	k	n	R²
ACET	3	1.807	0.213	0.993
	4	2.781	0.188	0.996
	5	10.478	0.076	0.999
	6	55.951	0.039	0.998
	7	79.806	0.015	1.000
XC-72R	3	1.149	0.340	0.963
	4	1.359	0.310	0.974
	5	1.843	0.276	0.983
	6	8.023	0.118	0.992
	7	14.300	0.067	0.996
BP2000	3	0.732	0.396	0.937
	4	0.961	0.389	0.962
	5	1.059	0.355	0.978
	6	1.218	0.320	0.978
	7	1.521	0.295	0.973
NG	3	0.052	1.000	—
	4	0.057	1.000	—
	5	0.070	1.000	—
	6	0.125	0.554	0.981
	7	0.674	0.233	0.981