Building Efficient Ion Pathway in Highly Densified Thick Electrodes with High Gravimetric and Volumetric Energy Densities.

Wu, Jingyi; Ju, Zhengyu; Zhang, Xiao; Takeuchi, Kenneth J; Marschilok, Amy C; Takeuchi, Esther S; Yu, Guihua · Nano Lett · 2021

basic_science · Level V

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Abstract

A common practice in thick electrode design is to increase porosity to boost charge transport kinetics. However, a high porosity offsets the advantages of thick electrodes in both gravimetric and volumetric energy densities. Here we design a freestanding thick electrode composed of highly densified active material regions connected by continuous electrolyte-buffering voids. By wet calendering of the phase-inversion electrode, the continuous compact active material region and continuous ion transport network are controllably formed. Rate capabilities and cycling stability at high LiFePO<sub>4</sub> loading of 126 mg cm<sup>-2</sup> were achieved for the densified cathode with porosity as low as 38%. The decreased porosity and efficient void utilization enable high gravimetric/volumetric energy densities of 330 Wh kg<sup>-1</sup> and 614 Wh L<sup>-1</sup>, as well as improved power densities. The versatility of this method and the industrial compatible "roll-to-roll" fabrication demonstrate an important step toward the practical application of thick electrodes.