Halide and Sulfide Electrolytes in Cathode Composites for Sodium All-Solid-State Batteries and their Stability.

Sodium all-solid-state batteries may become a novel storage technology overcoming the safety and energy density issues of (liquid-based) sodium ion batteries at low cost and good resource availability. However, compared to liquid electrolyte cells, contact issues and capacity losses due to interface reactions leading to high cell resistance are still a problem in solid-state batteries. In particular, sulfide-based electrolytes, which show very high ionic conductivity and good malleability, exhibit degradation reactions at the interface with electrode materials and carbon additives.

Protective NaSICON Interlayer between a Sodium-Tin Alloy Anode and Sulfide-Based Solid Electrolytes for All-Solid-State Sodium Batteries.

This paper presents a suitable combination of different sodium solid electrolytes to surpass the challenge of highly reactive cell components in sodium batteries. The focus is laid on the introduction of ceramic NaZrSiPO serving as a protective layer for sulfide-based separator electrolytes to avoid the high reactivity with the sodium metal anode. The chemical instability of the anode|sulfide solid electrolyte interface is demonstrated by impedance spectroscopy, X-ray photoelectron spectroscopy, and scanning electron microscopy.