The Effect of Slurry pH Values on The Electrochemical Properties of Manganese-Based-Oxide Electrode for Solid-State Batteries

With the rapid growth of electric vehicles, their conventional lithium-ion batteries (LIBs) are suffered from insufficient energy density and potential safety risks. High-capacity, earth- abundance, and low-flammability make manganese oxides a promising active material for anodes. Furthermore, the pH value of solid-state batteries (SSBs) influences lithiation and delithiation reactions, which in turn impacts the lithium wettability and interface resistance of SSBs. It is critical to study the effect of pH range so as to optimize the active materials and binders in manganese-based-oxide anodes.<br/><br/>In this work, the different pH values of electrode slurries will be investigated to improve the stability of binders and active materials. Furthermore, the pH value will be optimized to inhibit the unnecessary irreversible reactions during charge and discharge. It is expected that the optimized pH value of electrode slurries will enhance the retention, Coulombic efficiency, and rate-capability of the manganese-based-oxide anode in SSBs.<br/><br/>For the optimization of the pH value for manganese-based-oxide electrode slurries, water-based slurries will be produced by mixing manganese oxide powders, carbon black (super P), carboxymethyl cellulose (CMC), and styrene-butadiene rubber (SBR). The pH value of slurries will be adjusted with an oxalic acid. After that, the premixed slurries will be coated on copper foils by using a doctor blade, and then baked in a vacuum oven. After battery assembly, the electrochemical impedance spectroscopy (EIS) and galvanostatic charge-discharge (GCD) analyses will be applied to analyze the Coulombic efficiency, cycling life, and impedance variation resulted from different pH values. The composition and structure of active materials will be characterized by field-emission scanning electron microscopy (FE-SEM), energy-dispersive X-ray spectroscopy (EDX), and X-ray diffraction (XRD). This work will shed a light on controlling the pH value of manganese-based-oxide electrode slurries, for the improvement of SSB retention.