Hydrogen Bond Interaction in the Trade-Off Between Electrolyte Voltage Window and Supercapacitor Low-Temperature Performances

Liquid electrolyte determines the voltage window and extreme working temperature of supercapacitors. However, the effect of weak interaction between electrolyte species on voltage window and low-temperature capacitive performance is unclear. Herein, an electrolyte model system with increasing H-bond interaction was constructed to clarify this concern. The results indicated that strong H-bond interaction was positively correlated with the number of hydroxyls, which was beneficial to expand voltage window, but deteriorated rate performance; weak H-bond improved low-temperature performance. Supercapacitors with an optimized electrolyte presented high voltage and good low-temperature performance; even at -40 degrees C, the maximum energy density could be maintained at 7.0 Wh kg(-1) (>80 % retention relative to at -20 degrees C). This study revealed the mechanism of the influence of the H-bonds on electrolyte voltage window and anti-freezing capability and provided a new insight for the design of electrolytes with both high working voltage and low-temperature performance.

Automated summary

This study investigates the effect of weak interaction between electrolyte species on the voltage window and low-temperature capacitive performance of supercapacitors. The results show that strong H-bond interaction expands the voltage window but deteriorates rate performance, while weak H-bond improves low-temperature performance. Supercapacitors with optimized electrolytes exhibit high voltage and good low-temperature performance.