Determination and Engineering of Li‐Ion Tortuosity in Electrode Toward High Performance of Li‐Ion Batteries

Abstract With the progressively widespread application of lithium‐ion batteries, their energy density and power density are being pursued to the extremely high. However, both cannot be reached simultaneously at present. Tortuosity depicts the relationship in ionic diffusion between bulk electrolyte and the electrolyte in a porous electrode, provides information about channels within electrodes, and correlates the current dilemma between energy density and power capability of the lithium‐ion batteries. It is crucial to upgrade the fast charging and discharging performance of LIBs electrodes without losing volumetric energy density and using tortuosity as a guide is able to achieve this goal fundamentally. Meanwhile, tortuosity can serve as an evaluation parameter for production quality assessment, but this demands a fast, accurate, and cost‐effective measuring method. After the definition and measurement of tortuosity are provided, this article analyzes the structural influencing factors of tortuosity which have impacts on ion transportation and subsequently on tortuosity to facilitate a more systematic and comprehensive picture. Through the discussion of contradictions and influencing factors, a more refined transmission line model (the refined TLM) is perceived as the very first step to drive both aforementioned goals toward success and is discussed in the perspective part.