Micro-scale graded electrodes for improved dynamic and cycling performance of Li-ion batteries
Micro-scale graded electrodes for improved dynamic and cycling performance of Li-ion batteries
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DOI：
10.1016/j.jpowsour.2018.12.021
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发表时间：
2019-02-15
影响因子：
9.2
通讯作者：
Grant, Patrick S.
中科院分区：
文献类型：
--
作者：
Cheng, Chuan;Drummond, Ross;Grant, Patrick S.
基于LiFePO 4的锂离子电池阴极通过逐层喷涂方法制造，具有活性材料、导电碳和粘合剂的连续厚度梯度。与通常的均匀分布的阴极相比，但具有相同的平均组成，梯度电极的C速率和容量衰减性能都显着改善。例如，在2C下，具有优化的材料分布的分级阴极具有比喷涂均匀或常规浆料浇铸均匀阴极高15%和31%的放电容量，并且容量退化速率比2C下的均匀阴极慢40-50%。梯度电极的改进的性能被示出为源自于在高C-速率下较低的电荷转移电阻和降低的极化，这表明过电位的更空间均匀的分布，这导致在循环期间形成更薄的固体电解质界面，并维持改进的C-速率和长期循环性能。
Li-ion battery cathodes based on LiFePO4 are fabricated by a layer-by-layer spray printing method with a continuous through thickness gradient of active material, conductive carbon, and binder. Compared with cathodes with the more usual homogeneous distribution, but with the same average composition, both C-rate and capacity degradation performance of the graded electrodes are significantly improved. For example at 2C, graded cathodes with an optimized material distribution have 15% and 31% higher discharge capacities than sprayed uniform or conventional slurry cast uniform cathodes, and capacity degradation rates are 40-50% slower than uniform cathodes at 2C. The improved performance of graded electrodes is shown to derive from a lower charge transfer resistance and reduced polarization at high C-rates, which suggests a more spatially homogeneous distribution of over-potential that leads to a thinner solid electrolyte interphase formation during cycling and sustains improved C-rate and long-term cycling performance.