基于热应力分析的固体氧化物燃料电池阳极功能层优化设计

doi:10.15541/jim20160341

摘要/Abstract

摘要：

为了降低固体氧化物燃料电池在制备和工作过程中产生的热应力, 提高电池的电化学性能, 在电池中引入功能梯度层可以有效减小电池各层之间材料参数的差异, 从而缓解各层之间的热失配应力。本研究将阳极功能层引入燃料电池中, 通过阳极功能层子层数目和非线性梯度成分指数n控制各子层材料属性的变化情况, 研究了燃料电池在800℃下的热应力分布。结果表明: 选取适当的指数n和阳极功能层的分层数目可以明显降低阳极层的最大拉应力和电解质层的最大压应力。

关键词: 固体氧化物燃料电池, 分层法, 阳极功能层, 热应力

Abstract:

In order to reduce the thermal stress of solid oxide fuel cell in the process of preparation and working, and improve the electrochemical performance of the cell, the functionally graded layer is introduced into the cell. Due to the property of the functionally gradient material changes continuously or stepwise in a certain direction, the layer can reduce the difference of material parameters and relieve the thermal mismatch stress between layers effectively. On the basis of the previous research and the idea of hierarchical method, the anode functional layer is introduced into the solid oxide fuel cell, and the material parameters of the sub-layers are controlled through the anode functional layer number and the nonlinear gradient component exponent n. Thermal stress of the solid oxide fuel cell is studied at 800℃ within the operating temperature. The results show that the maximum tensile stress of the anode layer and the maximum compressive stress of the electrolyte layer decreases by introducing the anode functional layer. With the same anode functional layer number, the maximum tensile stress increases with the exponent n, and the maximum compressive stress of the electrolyte layer decreases with the exponent n increase. The thermal stress may lead to cracks and destroy the solid oxide fuel cell structure. This research provides theoretical basis for design and optimization of the solid oxide fuel cell.

Key words: solid oxide fuel cell, hierarchical method, anode functional layer, thermal stress

中图分类号:

TM911

谢佳苗, 王峰会. 基于热应力分析的固体氧化物燃料电池阳极功能层优化设计[J]. 无机材料学报, 2017, 32(4): 400-406.

XIE Jia-Miao, WANG Feng-Hui. Thermal Stress Analysis of Solid Oxide Fuel Cell with Anode Functional Layer[J]. Journal of Inorganic Materials, 2017, 32(4): 400-406.

图/表 11

图1 SOFC几何模型图

Fig. 1 Geometry models of SOFC(a) Without AFL; (b) With AFL

图2 AFL不同分层情况

Fig. 2 Different layer cases of AFL

表1 电极、电解质等的材料属性[19-21]

Table 1 Material properties of electrodes and electrolyte[19-21]

	T	NiO-YSZ	YSZ	LSM	NiO
E/GPa	20℃	127.3	215	110	110
E/GPa	800℃	105.5	185	118	90
$\mu $	20℃	0.33	0.308	0.36	0.34
$\mu $	800℃	0.33	0.313	0.36	0.34
CTE /×10^-6	20℃	11.77	7.6	9.8	13.0
	800℃	12.42	10.5	11.8	13.0
	1400℃	12.50	10.5	11.8	13.1

图3 分层梯度的材料模型[22]

Fig. 3 Model of graded elements[22]

图4 AFL各层NiO的体积分数与该层的相对位置之间的关系

Fig. 4 Relationship between volume fraction and normalized position of NiO in AFL

表2 各AFL子层中NiO的体积分数

Table 2 Volume fraction of NiO in AFL sublayers

Layer	AFL	NiO volume fraction
Layer	AFL	n=2	n=1	n=0.5
1	AFL1	20%	40%	56%
2	AFL1	5%	20%	40%
2	AFL2	45%	60%	69%
3	AFL1	2.5%	13%	32%
	AFL2	20%	40%	56%
	AFL3	55%	66%	73%
4	AFL1	1.3%	10%	27%
	AFL2	11.3%	30%	49%
	AFL3	31.0%	50%	63%
	AFL4	61.0%	70%	75%
5	AFL1	1%	8%	25%
	AFL2	7%	24%	43%
	AFL3	20%	40%	56%
	AFL4	39%	56%	66%
	AFL5	65%	72%	76%

图5 电解质层在20℃下的应力云图

Fig. 5 Minimum principal stress of YSZ under 20℃

表3 YSZ最大压应力结果对比

Table 3 Comparison results of the maximum compressive stresses of YSZ

	Presented model	Experimental	Numerical analysis
Max. compressive stresses of YSZ /MPa	633.3	670^[29]	608.46^[30]
Error	—	5.8%	3.9%

图6 阳极层的最大拉应力随AFL划分层数和指数n的变化情况(a)、未设置AFL的阳极应力云图(b)及n=0.5、AFL划分2层的应力云图(c)

Fig. 6 (a) Maximum tensile stresses of anode with the layers of AFL and the exponent n; (b) contour of anode without AFL; (c) contour of two layers of AFL (n=0.5)

图7 YSZ的最大压应力随AFL划分层数和指数n的变化情况(a)、未设置AFL的YSZ应力云图(b)及n=0.5、AFL划分1层的应力云图(c)

Fig. 7 (a) Maximum compressive stresses of YSZ with the layers of AFL and the exponent n, (b) contour of YSZ without the AFL and (c) contour of YSZ with two layers of the AFL (n=0.5)

图8 电解质层和阳极层界面两侧单元的最大主应力差(x=1、z=1)

Fig. 8 Maximum principal stress difference of interface element between YSZ and anode (x=1, z=1)

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