Building better all-solid-state batteries with Li-garnet solid electrolytes and metalloid anodes

All-solid-state batteries provide new opportunities to realize safe, non-flammable, and temperature-tolerant energy storage and display a huge potential to be the core of future energy storage devices, especially in applications where energy density is key to the technology. Garnet-type solid-state electrolytes based on cubic Li7La3Zr2O12 possess one of the highest Li+ conductivities, a wider electrochemical stability window compared to liquid electrolytes, and exceptional chemical and thermal stabilities among various solid electrolytes. Most of the first reports, however, employ lithium metal as the anode with unavoidable Li-dendrite formation through polycrystalline Li-garnet electrolytes at current densities above 0.5 mA cm−2. Accordingly, alternative materials and processing strategies for anodes or interlayers are inherently needed for high currents and fast charging for Li-garnet-type battery integration. Here, we demonstrate, through the use of a composite anode based on antimony nanocrystals, that metalloids offer high and stable storage capacities of up to 330 mA h g−1 for Li-garnet all-solid-state batteries at reasonably high current densities (e.g. 240 mA g−1) at 95 °C. The results are also compared towards standard liquid type electrolytes and reveal high coulombic efficiencies and improved cycle stability for the solid-state cell design. Guidelines and aspects to process alternative materials and impact the interface design towards fast lithium charge transfer between the metalloid and the Li-garnet electrolyte are formulated. The architecture and scalable processing of metalloid-based batteries are obvious advantages of this work, opening a promising avenue to avoid Li-dendrite formation at high current loads in garnet-type all-solid-state rechargeable batteries.