Sulfonated Hollow Silica Spheres as Electrolyte Store/Release Agents: High-Performance Supercapacitor Applications

Sulfonated hollow silica spheres (HSS-S) are synthesized and applied in supercapacitors as acid-filling and acid-releasing agents in a polymer matrix, thanks to their unique architecture wherein the hollow spheres can be filled with acid (HSS-S-F) and can be dispersed in poly(vinyl alcohol) (PVA) with various weight fractions to produce nanocomposite gel polymer electrolytes (GPEs), HSS-S/PVA, and HSS-S-F/PVA. The symmetrical supercapacitor device is assembled using an active carbon(AC) electrode and the GPE HSS-S-F/PVA shows a specific capacitance value of 147 F g⁻¹ at 0.5 A g⁻¹. Alternatively, the GPE HSS-S/PVA shows a specific capacitance of 52 F g⁻¹ at the same current density. The symmetrical supercapacitor based on HSS-S-F/PVA has a high-energy density of 20.40 W·h kg⁻¹ at a power density of 545 W kg⁻¹ with a remarkable cyclic stability with a loss of only 15% after 2250 charge–discharge cycles. This excellent property demonstrates that HSS-S is a promising additive and has the potential to produce more efficient energy storage devices by changing the hollow particle size, pore size, and using different host polymer electrolytes.