Despite the widespread interest in electrolytic Zn-MnO2 batteries with excellent output voltage and high theoretical capacity, the spontaneous disproportionation reaction of free Mn3+ along with the disorderly deposited inactive MnO2 results in the low Mn2+/MnO2 conversion reversibility, which seriously affects their cycling stability. Here, we propose a novel aqueous SiO2 colloidal electrolyte with FeSO4 mediator (denoted as SF electrolyte) based on a bidirectional electrochemical-chemical model to achieve dual regulation of the MnO2 deposition/dissolution process. During the charging process, the SiO2 colloidal particles located at the carbon felt interface and the electrolyte bulk phase simultaneously provide sufficient disproportionation sites for the diffused Mn3+ to guide the orderly rapid deposition of MnO2. Meanwhile, the introduction of Fe2+ mediators during the discharge process can sufficiently react with MnO2 on the SiO2 particles in the electrolyte, thereby further enabling the efficient conversion of Mn2+/MnO2. Consequently, electrolytic Zn-MnO2 battery with SF electrolyte can stably run for 550 cycles at 10 mA h cm-2 and achieve superior reversibility at a high area capacity of 20 mA h cm-2. This work demonstrates the feasibility of colloidal electrolytes in modulating electrochemical-chemical processes to stabilize electrolytic Zn-MnO2 batteries.