论文标题
电池多孔电极中反应不均匀的热力学起源及其缓解
Thermodynamic Origin of Reaction Non-Uniformity in Battery Porous Electrodes and its Mitigation
论文作者
论文摘要
多孔电极中非均匀反应电流分布的发展是电池充电 /放电过程中普遍存在的现象，并且经常控制电池电池的速率性能。多孔电极中的反应不均匀性归因于电解质和/或固体电极相内的质量转运的动力学限制。但是，在这项工作中，我们揭示了它也受到电极材料的固有热力学行为的强烈影响，特别是当平衡电位曲线的斜率减少时，平衡电位对电荷状态的依赖性越来越明显。我们采用数值模拟和等效电路模型来阐明这种相关性，并表明反应程度不均匀性和所得的放电能力可以通过无量纲的反应均匀性数来预测。对于对电荷状态不敏感并表现出明显不均匀性的电势的电极材料，我们演示了几种方法，可以将空间匀浆化的多孔电极内部反应电流（包括匹配电子和离子电极），引入分级的电子电导率并降低表面反应动力学。
The development of non-uniform reaction current distribution within porous electrodes is a ubiquitous phenomenon during battery charging / discharging and frequently controls the rate performance of battery cells. Reaction inhomogeneity in porous electrodes is usually attributed to the kinetic limitation of mass transport within the electrolyte and/or solid electrode phase. In this work, however, we reveal that it is also strongly influenced by the intrinsic thermodynamic behavior of electrode materials, specifically the dependence of the equilibrium potential on the state of charge: electrode reaction becomes increasingly non-uniform when the slope of the equilibrium potential curve is reduced. We employ numerical simulation and equivalent circuit model to elucidate such a correlation and show that the degree of reaction inhomogeneity and the resultant discharge capacity can be predicted by a dimensionless reaction uniformity number. For electrode materials that have equilibrium potentials insensitive to the state of charge and exhibit significant reaction non-uniformity, we demonstrate several approaches to spatially homogenizing the reaction current inside porous electrodes, including matching the electronic and ionic resistances, introducing graded electronic conductivity and reducing the surface reaction kinetics.
