Effect of Silicon-Graphite-Based Anode Slurry Storage Conditions on Rheology, Stability, and Electrochemical Performance

Storage of electrode slurries between mixing and coating can affect electrode quality and subsequent cell performance. Here, water-based silicon/graphite anode slurries with five Si/C composite-to-graphite ratios were stored for up to 14 d under continuous stirring at room temperature (RT) or statically at 5 °C and compared with previously reported static RT storage. Rheology, zeta potential, maximum particle size, and electrochemical performance were evaluated. All slurries remained shear-thinning, but viscosity decreased during storage. Continuous stirring maintained macroscopic homogeneity while accelerating rheological and electrokinetic degradation, whereas static storage at 5 °C preserved the rheological state closest to the fresh slurry and caused the smallest zeta-potential shift. For the RT-stored slurries, no systematic increase in maximum particle size was observed. Rheological and electrokinetic results instead indicated degradation at the particle-binder network and particle-liquid interfaces. Coin full-cell tests with 4.4 mAh cm −2 anodes showed that storage effects depended strongly on active-material composition and storage condition. For the silicon-rich formulation, 14 d at RT resulted in approximately 12%–13% greater capacity loss than for cells prepared from the corresponding fresh slurry, whereas storage at 5 °C limited this storage-related increase to ∼3% after the 200-cycle long-term cycling protocol.