• A system-level strategy is presented to achieve high charging efficiency in triboelectric nanogenerator (TENG)-supercapacitor (SC) hybrid devices, with a focus on frequency response design.
• This study reveals that the high-frequency characteristics of SCs and the prolonged output pulse duration of TENGs are critical for achieving high charging efficiency.
• A three-dimensional hollow-structured MXene is synthesized as a high-frequency SC electrode material, demonstrating a twofold increase in charging efficiency compared to conventional SCs.
• The study highlights the importance of frequency response design in developing efficient chargeable TENG–SC hybrid devices.