The need of energy storage is a priority to minimize fluctuations of renewable energy sources in the electric grid and to comply with the increasing energy demand. One of the technologies with higher potential to store energy is the semi-solid Zinc-Air RFB. In this study a zinc slurry, consisting in zinc microparticles dispersed in alkaline electrolyte using different gelling agents, works as a flowing electrode and their performance is evaluated by discharge kinetics. Challenging conditions reduce the availability of rheology modifiers able to produce homogenous dispersions over time. This approach substitutes the commonly used zinc plate working as fixed electrode and its configuration reaches higher energy densities. Slurry formulation have a great impact on battery performance. Carbopol and attapulgite were used here mainly because of their stability under process conditions. Gelling agent concentration is assessed by the slurry anode electrolyte performance in a zinc-air RFB. A synergistic effect is found when mixing the two gelling agents, reaching approximate 4-times higher current densities when compared to each of the gelling agents alone. Rheological characterizations were performed on the new gelled matrix and slurries to determine their behavior and relationship with the interesting electrochemical results. It is found that increasing concentration of Carbopol increases the slurry elasticity and yield stress. On the other hand, higher concentrations of Carbopol leads to highly viscous slurries that despite of showing lower charge transfer resistance, do not reach the desired current density. Flow curves of slurries were fitted to the Herschley-Bulkley model, providing useful information about their flow behavior. Battery performance can be improved by optimizing formulation of anode slurry electrodes, at the same time rheology plays an important role as the design of the cell can be tuned-up by simulating the flow of slurries with defined flow behavior