Diffusion Enhancement in Lithium Secondary Batteries for Safe and Long-Term Cycling

The increasing demand for lithium batteries with superior energy and power density levels is fueled by their expanding role in diverse applications. However, ion transport limitations constitute the critical barrier to achieving advanced lithium batteries. Specifically, sluggish lithium-ion diffusion during fast charging/discharging directly triggers electrode degradation, electrolyte decomposition, and interfacial instability, severely restricting energy density and cycle life. Addressing this challenge requires the fundamental optimization of diffusion kinetics and their compatibility with electrochemical interfaces. In this review, a chemical engineering framework is employed to dissect mass transfer barriers across essential battery components, including electrolytes plagued by conductivity-induced concentration gradients, solid electrolyte interphases with intrinsically restricted lithium-ion conduction, and electrodes constrained by diffusion limitations. Unlike conventional material‑specific modifications, the engineering approach of applying external physical fields actively regulates ion transport across different battery components and can be universally applicable. Limitations of the current technologies, including their field penetration constraints and scalability issues, are further noted. Finally, targeted research priorities, including multifield coupling systems, field-responsive interphases, and a multiscale in situ characterization that bridges ion dynamics with battery performance, are identified. This work establishes foundational principles for mastering transport phenomena, accelerating the ability of next-generation lithium batteries to meet extreme operational demands.