Multiscale coupled electron–ion transport in semi-solid lithium flow batteries

Abstract

Semi-solid lithium flow batteries (LFBs), inheriting the advantages of high scalability of flow batteries (FBs) and high energy density of rechargeable lithium ion batteries (LIBs), are considered as an emerging technology for grid-scale energy storage. Distinct from traditional FBs and LIBs, semi-solid LFBs employ multiphase electrodes containing solid particles and liquid electrolyte. Such semi-solid electrodes are always under flowable and dynamic state during operation, leading to multiscale coupled reaction dynamics and unique charge transport mechanisms. Understanding the intrinsic electron–ion transport mechanisms and homogenizing transport kinetics is imperative for the rational optimization of semi-solid LFBs. Nevertheless, the unique electron–ion transport mechanisms and design strategies for manipulating charge transport kinetics have rarely been systematically elucidated and analyzed. Hence, this review provides a comprehensive understanding and recognization of intrinsic electron–ion transport mechanisms via decoupling charge transport processes in semi-solid LFBs over multiscale domains. Meanwhile, current strategies to manipulate multiscale electron–ion transport kinetics of semi-solid electrodes and membranes are systematically summarized. Moreover, we highlight the multi-physics field modelling of semi-solid LFBs to fundamentally understand the correlation between the electrochemistry and battery structure. In particular, potential advantages and challenges toward commercialization of semi-solid LFBs are also assessed. Finally, future perspectives on crucial scientific and practical issues for different development stages are outlined. This review aims to bridge the current research gap between fundamental electrochemistry and commercial applications of semi-solid LFBs, which will accelerate their deployment in the field of energy storage.