Systematic Optimization of High‐Energy‐Density Li–Se Semi‐Solid Flow Battery
Kai Huang, Pei Zhou, Hongning Chen
Abstract
Redox flow batteries (RFBs) are still unable to be applied in more fields due to their low energy density. This work proposes a high‐energy‐density Li–Se semi‐solid flow battery (SSFB), and improves its performance through an optimization process. The effect of composite synthesis, current collector types, and electrolyte solvent types are systematically studied. The method of impregnating Se and Ketjen black (KB) directly according to their proportion in the suspension as a composite without adding additional KB can not only effectively improve the stability and utilization of suspension, but also greatly reduce its viscosity. Carbon paper is used as the current collector to improve the performance of the system by its smaller contact resistance. The selected solvent of tetraethylene glycol dimethyl ether (TEGDME) has smaller volatility and a larger contact angle, which contributes to the formation of a stable and uniform suspension. After optimization, the demonstrated system has achieved a volumetric capacity of 156–386 Ah L −1 with high Coulombic efficiency (≈100%) for 100 cycles. Finally, the intermittent‐flow mode test has confirmed the applicability of the system. This research provides a reference for the practical application of SSFBs and a direction for the optimization of other types of suspensions.