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The effect of surface-bulk potential difference on the kinetics of intercalation in core-shell active cathode particles
Journal of Power Sources ( IF 9.2 ) Pub Date : 2018-02-22 , DOI: 10.1016/j.jpowsour.2018.02.023
Saeed Kazemiabnavi , Rahul Malik , Bernardo Orvananos , Aziz Abdellahi , Gerbrand Ceder , Katsuyo Thornton

Surface modification of active cathode particles is commonly observed in battery research as either a surface phase evolving during the cycling process, or intentionally engineered to improve capacity retention, rate capability, and/or thermal stability of the cathode material. Here, a continuum-scale model is developed to simulate the galvanostatic charge/discharge of a cathode particle with core-shell heterostructure. The particle is assumed to be comprised of a core material encapsulated by a thin layer of a second phase that has a different open-circuit voltage. The effect of the potential difference between the surface and bulk phases (Ω) on the kinetics of lithium intercalation and the galvanostatic charge/discharge profiles is studied at different values of Ω, C-rates, and exchange current densities. The difference between the Li chemical potential in the surface and bulk phases of the cathode particle results in a concentration difference between these two phases. This leads to a charge/discharge asymmetry in the galvanostatic voltage profiles, causing a decrease in the accessible capacity of the particle. These effects are more significant at higher magnitudes of surface-bulk potential difference. The proposed model provides detailed insight into the kinetics and voltage behavior of the intercalation/de-intercalation processes in core-shell heterostructure cathode particles.



中文翻译:

表面体电势差对核-壳型活性阴极颗粒内插动力学的影响

活性阴极颗粒的表面改性通常在电池研究中观察到,要么是在循环过程中形成的表面相,要么是经过有意设计以提高阴极材料的容量保持率,倍率能力和/或热稳定性。在这里,建立了一个连续尺度模型来模拟具有核-壳异质结构的阴极颗粒的恒电流充/放电。假定该颗粒由被具有不同开路电压的第二相的薄层包封的芯材料组成。表面相和本体相之间的电势差的影响(Ω)上的锂嵌入动力学和恒电流充/放电曲线在不同的温度下进行了研究 Ω,C速率和交换电流密度。阴极颗粒的表面相和本体相中的Li化学势之间的差异导致这两个相之间的浓度差异。这导致恒电流电压曲线中的充电/放电不对称,导致颗粒的可利用容量降低。这些效应在较高的表面体电位差时更为显着。所提出的模型提供了对核-壳异质结构阴极颗粒中的嵌入/脱嵌过程的动力学和电压行为的详细了解。

更新日期:2018-02-22
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