Effects of volume variations under different compressive pressures on the performance and microstructure of all-solid-state batteries
Effects of volume variations under different compressive pressures on the performance and microstructure of all-solid-state batteries
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DOI：
10.1016/j.jpowsour.2020.228595
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发表时间：
2020-10
影响因子：
9.2
通讯作者：
Mari Yamamoto;Y. Terauchi;A. Sakuda;A. Kato;Masanari Takahashi
中科院分区：
文献类型：
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作者：
Mari Yamamoto;Y. Terauchi;A. Sakuda;A. Kato;Masanari Takahashi
采用硫化物固体电解质（SE）的全固态电池在运行过程中施加的压缩压力有助于颗粒接触，从而维持离子和电子传导网络。活性材料的压缩压力和体积变化之间的关系对于设计具有增强的基于电池的能量密度的实用全电池至关重要。然而，对这些方面的研究却很少。在这里，我们系统地研究了活性材料 [硅、石墨和 LiNi1/3Mn1/3Co1/3O2(NMC)] 在不同压力（75 和 50 MPa）下的体积变化对电化学性能、电池内阻和具有薄 SE 层（约 75 μm 厚）的全电池微观结构的影响。 75 MPa 的加压和使用较低膨胀率的石墨可提高容量和容量保持率。负极体积变化的增加会增加 NMC 复合层中的电荷转移电阻和裂纹形成。这表明薄SE层的弹性变形的缓冲效果不足。压力促进LixSi和SE的塑性变形，从而改善它们的接触，而垂直裂纹出现在整个硅复合层中，有效地减轻了因硅体积变化而产生的应力。这项研究为工业应用所需的先进活性材料和电池的设计提供了重要的机制见解。
Compressive pressure applied during the operation of all-solid-state batteries that employ a sulfide solid electrolyte (SE) assists particle contact, thereby maintaining the ionic and electronic conduction network. The relationship between compressive pressure and volume variation in active materials is critical for designing practical full-cells with enhanced cell-based energy densities. However, studies into these aspects are rare. Here, we systematically investigate the effects of volume change of active materials [silicon, graphite, and LiNi1/3Mn1/3Co1/3O2(NMC)] at different pressures (75 and 50 MPa) on electrochemical performance, cell internal resistance, and microstructure of full-cells with a thin SE layer (approximately 75-μm-thick). Pressurization at 75 MPa and use of graphite with lower expansion ratios improves capacity and capacity retentions. Increasing variation in the negative electrode volume increases charge-transfer resistance and crack formation in the NMC-composite layer. This indicates that the buffering effect via the elastic deformation of the thin SE layer is insufficient. Pressure facilitates plastic deformation of LixSi and SE, resulting in their improved contact, while perpendicular cracks appear throughout the Si-composite layer, effectively alleviating stress derived from variations in the volume of Si. This study provides important mechanistic insights into the design of advanced active materials and batteries required for industrial applications.