Li4Ti5O12 (LTO) is considered the anode material of choice for low-cost, high-power lithium-ion batteries. Advantageously, just as in the case of graphite-based electrodes, also LTO electrodes can be prepared using water-soluble, fluorine-free polymers as binder and water as the processing solvent, rendering the fabrication sustainable and cost-efficient. Recently, we optimized the aqueous processing of lithium transition metal oxide cathodes by adding phosphoric acid to the electrode slurry, yielding enhanced electrochemical performance and a stabilized electrode|electrolyte interface.[3,4] Herein, we present our research towards the optimization of the aqueous electrode preparation for LTO anodes including the addition of phosphoric acid. In fact, we found that the electrode slurry composition and the processing parameters have to be very carefully selected to obtain long-term stable, high-performance LTO electrodes. For instance, improper mixing conditions and slurry compositions result in the formation of Li3PO4 particles, which leads, amongst others, to inferior mechanical properties of the electrode. In addition, a negative impact on the crystal structure and surface of the LTO active material was observed. However, these findings eventually enabled the realization of high-mass loading electrodes with superior performance thanks to the carefully optimized slurry composition including an additional processing additive and optimized electrolyte composition. This optimization results in lower cell polarization at elevated dis-/charge rates, increased apparent lithium-ion diffusion and charge transfer, as well as enhanced cycle life in half-cells and full-cells at low and high dis-/charge rates.