Enhanced homogeneity of electrochemical reaction via low tortuosity enabling high-voltage nickel-rich layered oxide thick-electrode

Abstract

Inhomogeneous electrochemical reactions during the charging-discharging process of high-voltage nickel-rich layered oxide cathodes play a major role in cracks formation and deteriorating cyclability. Especially in thick electrodes, the severe concentration polarization aggravates the inhomogeneity and further diminishes the cycle life. In this work, a low-tortuous thick electrode of LiNi0.7Co0.1Mn0.2O2 (NCM712) is constructed by the ice-templating strategy and the effect of low tortuosity on electrochemical performance is investigated. Low-tortuous NCM712 electrode exhibits reduced concentration polarization and fast lithium-ion transport kinetics, consequently enabling superior rate capability. Furthermore, benefiting from the effective electronic and ionic transport network in low-tortuous thick electrode, NCM712 particles present homogeneous electrochemical reaction and alleviated intragranular stress, which suppresses cation mixing and cracking formation at high voltage condition. The homogeneity of electrochemical reaction in the low-tortuous thick electrode is favorable to attain the structural integrity, the robust electrolyte interface and superior cyclability. This strategy provides a new concept to homogenize the electrochemical reaction of thick nickel-rich layered oxide electrodes by low tortuosity electrode architecture design, leading to superb electrochemical performance with high energy density.