Colloidal electrolyte–mediated dispersion and transport mechanism: Enhancing stability and efficiency of MnO2-based slurry flow battery

Slurry flow batteries have recently garnered escalating attention due to their super-high theoretical capacity (utilizing insoluble redox-active materials and breaking through the solubility limit). Nevertheless, several longstanding and intractable issues, such as insoluble materials activity, cycling stability and static stability, must be resolved. This study demonstrates an innovative colloidal electrolyte-mediated dispersion and transport mechanism within a MnO 2 -based slurry flow battery (MnO 2 -SFB). Specifically, the MnO 2 particles are produced on the surface of colloidal substances and co-flow therewith. In this way, agglomeration and sedimentation are prevented, which helps maintain the stability of MnO 2 -SFB. Simultaneously, owing to the robust charge interaction among the colloidal materials and MnO 2 , the dispersion of MnO 2 particles is enhanced. During the discharge process, the reduction activity is augmented via the synergistic effect of electrochemical and chemical reactions, thus ensuring the reversibility of the battery. Consequently, the PBI-MnO 2 -SFBs can achieve running stability for over 300 cycles at 80 mA   cm −2 with an average energy efficiency of 81 % at a volume capacity of 42.8 Ah L −1 . Moreover, the MnO 2 -SFBs with PBI colloidal material can work effectively after static for over 60 days, which is, to our knowledge the highest value ever reported for slurry flow batteries. Overall, this study provides new insights into exhibiting highly reversible and long-cycling-capability slurry flow batteries and promotes their development.