Dispersed nickel-cobalt double metal hydroxide self-assembled with polystyrene sulfonic acid polyelectrolyte for the preparation of carbon solid solid supercapacitors with wide temperature range and long cycle stability

Highlights: • PSS/NiCo-LDHs composite polyelectrolyte was prepared. • The specific capacitance of activated carbon electrodes reaches 119.8 F g⁻¹ at 80 °C. • The capacitance retention rate of activated carbon electrodes remains 96.2% after 5000 cycles. Although polyelectrolytes with good electrochemical compatibility have been widely used in all solid-state supercapacitors, the random dispersion of polymer chains results in a narrow operating temperature range, which limits its further application. Herein, through the electrostatic attraction assembly strategy, the negatively charged polystyrene sulfonic acid (PSS) and the positively charged layered nickel-cobalt double hydroxide (NiCo-LDH) nanosheets are synthesized into PSS/NiCo-LDH composite electrolyte. Meanwhile, the polyelectrolyte shows a wide temperature application range (20–80 °C) and excellent electrochemical cycle stability in solid supercapacitor (capacitance retention rate reaches 96.2% after 5000 cycles) based on activated-carbon electrodes. The remarkable thermal stability and electrochemical performance are mainly attributed to the addition of NiCo-LDH, which is not only limit the thermal decomposition of PSS molecular chains, but also accelerate the migration rate of electrolyte ions. This work opens a way for the preparation of polyelectrolyte with wide temperature range and long cycle stability for application in solid-state supercapacitors.