Tailoring the Heterostructure Interfaces of Solid-State Supercapacitors for High-Power Density

Solid-state supercapacitors (SSCs) using gel electrolytes show high promise for safety and mechanical flexibility, but their power densities are typically lower than those using liquid electrolytes due to the ill-fitted heterostructure interfaces among gel electrolyte, electrode film, and current collector. Herein, a strategy of tailoring the heterostructure interfaces is proposed, where the current collector and electrode film are one-step microimprinted into a unified film with dual 3D microstructures at their interface and surface, facilitating infiltration of gel electrolyte and ion/electron transport concurrently. As a result, the generated SSCs based on activated carbon retain 81% capacitance at a high current density of 30 A g^-1, not less than that using the corresponding liquid electrolyte. Moreover, the pouch SSCs with a capacitance of 436 F deliver a high-power density of 12.8 kW kg^-1, and cylindrical SSCs can withstand an ultrahigh impact pressure of up to 67 GPa, equivalent to an extreme impact of up to 60 000 times the acceleration of gravity, demonstrating ultra-high safety. More importantly, a 5 m tailored electrode film can be fabricated within 2 min using the roll-to-roll process, demonstrating the high scalability for large-scale capacitive energy storage.