For the development of light, flexible, and wearable electronic devices, it is crucial to develop energy storage components combining high capacity and flexibility. Herein, an all-solid-state supercapacitor is prepared through an in situ growth method. The electrode contains polyaniline deposited on a carbon nanotube and a poly (ethylene-co-vinyl acetate) film. The hybrid electrode exhibits excellent mechanical and electrochemical performance. The optimized few-layer polyaniline wrapping layer provides a conductive network that effectively enhances the cycling stability, as 66.4% of the starting capacitance is maintained after 3000 charge/discharge cycles. Furthermore, the polyaniline (PANI)-50 displays the highest areal energy density of 83.6 mWh·cm⁻², with an areal power density of 1000 mW·cm⁻², and a high areal capacity of 620 mF cm⁻². The assembled device delivers a high areal capacity (192.3 mF·cm⁻²) at the current density of 0.1 mA·cm⁻², a high areal energy (26.7 mWh·cm⁻²) at the power density of 100 mW·cm⁻², and shows no significant decrease in the performance with a bending angle of 180°. This unique flexible supercapacitor thus exhibits great potential for wearable electronics.

In this work, we present a cellulose acetate membrane flexible supercapacitor prepared through a direct writing method. A carbon nanotube (CNT) and silver (Ag) nanoparticle were prepared into ink for direct writing. The composite electrode displayed excellent electrochemical and mechanical electrochemical performance. Furthermore, the CNT-Ag displayed the highest areal capacity of 72.8 F/cm³. The assembled device delivered a high areal capacity (17.68 F/cm³) at a current density of 0.5 mA/cm², a high areal energy (9.08–5.87 mWh/cm³) at a power density of 1.18–0.22 W/cm³, and showed no significant decrease in performance with a bending angle of 180°. The as-fabricated CNT/Ag electrodes exhibited good long-term cycling stability after 1000 time cycles with 75.92% capacitance retention. The direct writing was a simple, cost-effective, fast, and non-contact deposition method. This method has been used in current printed electronic devices and has potential applications in energy storage.