Batteries In an electrochemical cell, the electrolyte has the role of separating and shuttling ions to produce a current. A good electrolyte thus should have high ionic conductivity and good thermal and electrochemical stability, although many in use do not have all these attributes. For example, solid electrolytes can show greater stability, but they are often poorer conductors. Joos et al. consider a deep eutectic solvent, in which the combination of two compounds radically lowers the melting temperature, immobilized within a silica matrix to form a gel. This material was easily processed, had decent ionic conductivity and thermal stability up to 130°C, and was successfully cycled in a Li/LiFePO4 cell. Chem. Mater. 10.1021/acs.chemmater.7b03736 (2018).