Advanced electrolyte with high stability and low-temperature resistance for zinc-ion batteries

Aqueous zinc-ion batteries (AZIBs) are considered to be a green and safe energy storage system. However, electrolyte leakage, zinc dendrite growth and side reactions are still barriers to their practical application. A quasi-solid sodium alginate gel electrolyte (GE) was designed to alleviate these pain points. To further stabilize the water molecules in this GE and extend its application to subzero temperatures, a disaccharide called trehalose (TreH) was introduced as a multifunctional additive. The rational introduction of TreH notably improved the strength (186.6 kPa) of the sodium alginate GE while retaining a high ionic conductivity (22.4 mS cm-1) at 25 degrees C. The zinc-polyaniline full battery assembled with this composite GE exhibited a capacity retention of 70.4% after 500 cycles at 25 degrees C, and still delivered a reversible capacity of 120.6 mA h g-1 at -20 degrees C. These results show that the sodium alginate GE with trehalose as an additive has great potential for development in AZIBs. Sodium alginate was selected as a matrix and trehalose was employed as an additive to form a hydrogel electrolyte for Zn-ion batteries applied at low temperatures.