Improved Rate Capability in Composite Solid-State Battery Electrodes Using 3‑D Architectures

The limited rate capability observed at faster charging rates is a critical challenge for composite electrodes in solid-state batteries (SSBs). This becomes further amplified with increasing electrode thickness and higher ratios of active material to solid electrode, which result in trade-offs between energy and power density. To overcome these trade-offs, it is necessary to understand the factors responsible for poor rate capability by exploring new approaches to boost power density without compromising energy density. Herein, we fabricated 3-D patterned composite graphite (Gr/Li₆PS₅Cl) electrodes with low-tortuosity electrolyte channels using a templating approach. Graphite was chosen as a model system to study inhomogeneous lithiation in composite SSB electrode architectures because of the visible color changes that occur as a function of local state-of-charge. At faster cycling rates (1C), the 3-D patterned electrodes enabled considerably higher accessible capacity (38% increase) compared to the unpatterned control electrodes. These enhancements were visualized using operando video microscopy, where 3-D electrode architectures showed improved homogeneity in the local state-of-charge throughout the electrode thickness. The insights presented here will enable new strategies based on 3-D electrode architectures to overcome power/energy trade-offs in SSBs.