An Energy‐Adjustable, Deformable, and Packable Wireless Charging Fiber Supercapacitor

Abstract Wireless charging energy storage devices eliminate bulky wires of wearable electronics. However, rigid shape and specific charging energy restrict their applications in space‐limited portable electronics. Herein, an all‐carbon fiber supercapacitor is presented that features shape‐adjustable, packable, and energy‐controllable wireless charging functions. With the unique on‐dimensional circuit structure, the maximum energy transfer efficiency from the electrical energy received by the wireless charging unit to the output energy of the fiber supercapacitor can reach up to ≈60.8%, and meanwhile this integrated fiber device exhibits an outstanding area capacity of 803 mF cm −2 and energy density of 1004 µWh cm −2 , superior to most of the fiber supercapacitors. Moreover, this unique device can endure significant deformation in shape of circles ranging from 2 to 20 cm diameter, and can be packed into narrow spaces, such as smart bracelet and disk‐shaped pet global positioning system (GPS). By altering the device shape, the wireless charging current, voltage, and power can be adjusted in the range of 0.5–20 mA, 1.4–15.5 V, and 0.003–313 mW, accommodating the energy requirements for nearly all existing micro‐electronics. This work offers unprecedented opportunities for packable, space‐confined and energy harvesting controllable wearable electronics.