The effects of state of charge (SOC) on the elastic properties of 3D structural battery composites are studied. An analytical model based on micromechanical models is developed to estimate the effective elastic properties of 3D structural battery composite laminae at different SOC. A parametric study is performed to evaluate how different design parameters such as volume fraction of active materials, stiffness of constituents, type of positive electrode material, etc. affect the moduli of the composite lamina for extremes in SOC. Critical parameters and configurations resulting in large variations in elastic properties due to change in SOC are identified. As the extreme cases are of primary interest in structural design, the effective elastic properties are only estimated for the electrochemical states corresponding to discharged (SOC=0) and fully charged (SOC=1) battery. The change in SOC is simulated by varying the volume and elastic properties of the constituents based on data from literature. Parametric finite element (FE) models for square and hexagonal fibre packing arrangements are also analysed in the commercial FE software COMSOL and used to validate the analytical model. The present study shows that the transverse elastic properties and and the in-plane shear modulus are strongly affected by the SOC while the longitudinal stiffness is not. Fibre volume fraction and the properties of the coating (such as stiffness and Poisson’s ratio) are identified as critical parameters that have significant impact on the effect of SOC on the effective elastic properties of the composite lamina. For configurations with fibre volume fraction ≥ 0.4 and Young’s modulus of the coating of 1 GPa or higher, the transverse properties and change more than 30% between extremes in SOC. Furthermore, for configurations with high volume fractions of electrode materials and coating properties approaching those of rubber the predicted change in transverse stiffness is as high as +43%. This shows that it is crucial to take effects of SOC on the elastic properties into account when designing 3D structural battery composite components.

中文翻译：

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荷电状态对3D结构电池复合材料弹性性能的影响

研究了荷电状态 (SOC) 对 3D 结构电池复合材料的弹性性能的影响。开发了基于微机械模型的分析模型，以估计 3D 结构电池复合材料薄片在不同 SOC 下的有效弹性性能。进行参数研究以评估不同的设计参数（例如活性材料的体积分数、成分的刚度、正极材料的类型等）如何影响复合材料薄片在 SOC 极端情况下的模量。确定了因 SOC 变化而导致弹性特性发生较大变化的关键参数和配置。由于极端情况是结构设计的主要关注点，仅针对对应于放电 (SOC=0) 和完全充电 (SOC=1) 电池的电化学状态估计有效弹性特性。根据文献数据，通过改变成分的体积和弹性特性来模拟 SOC 的变化。在商用有限元软件 COMSOL 中还分析了方形和六边形纤维填料排列的参数化有限元 (FE) 模型，并用于验证分析模型。本研究表明，横向弹性特性和面内剪切模量受 SOC 的强烈影响，而纵向刚度则不受此影响。纤维体积分数和涂层的特性（例如刚度和泊松比）被确定为关键参数，这些参数对 SOC 对复合材料层板的有效弹性特性的影响具有显着影响。对于纤维体积分数 ≥ 0.4 和 1 GPa 或更高涂层杨氏模量的配置，横向特性 和 SOC 在两个极端之间变化超过 30%。此外，对于具有高体积分数的电极材料和接近橡胶的涂层性能的配置，横向刚度的预测变化高达 +43%。这表明在设计 3D 结构电池复合组件时考虑 SOC 对弹性性能的影响至关重要。4和1GPa或更高的涂层的杨氏模量，横向性能和SOC在极端之间变化超过30%。此外，对于具有高体积分数的电极材料和接近橡胶的涂层性能的配置，横向刚度的预测变化高达 +43%。这表明在设计 3D 结构电池复合组件时考虑 SOC 对弹性性能的影响至关重要。4和1GPa或更高的涂层的杨氏模量，横向性能和SOC在极端之间变化超过30%。此外，对于具有高体积分数的电极材料和接近橡胶的涂层性能的配置，横向刚度的预测变化高达 +43%。这表明在设计 3D 结构电池复合组件时考虑 SOC 对弹性性能的影响至关重要。