Improvement in electromechanical performance of degradable bio‐inspired soft ionic actuators with high energy density conductive electrodes

Abstract Recently, renewable natural electroactive soft ionic actuators have attracted widespread attention to its potential applications in biomedical equipment, soft robots, and micro‐nano actuators and sensors, and so on. However, low‐energy conversion rates, unstable stability, and slow response speed that severely constrain their practical application. In this article, three kinds of conductive nanoparticles (polyaniline [PANI], polythiophene and its derivatives [PEDOT], and acetylene black [ACET]) are co‐doped into the electrodes of chitosan/MCNT/rGO to prepare high performance soft ionic actuators, and specific capacitance, energy density, cycling stability, and conductivity have been significantly improved. Results showed that after doping three kinds of conductive nanoparticles, the electrode has the highest energy density (up to 145.922 Wh Kg⁻¹), the highest conductivity (up to 850.91 S m⁻¹) and good cycling stability with 82.55% of initial capacitance after 10 000 cycles. After assembling, ionic actuators have the maximum deflection displacement (up to 17.50 mm) increased by 7.6 times and the largest output force (up to 4.795 mN) increased by 2.465 times under power‐on excitation for 120 seconds of 5 V DC voltage. In addition, the displacement of ionic actuators with doping ACET electrode is better than actuators with the doped PANI electrode, while the output force of ionic actuators with doping PANI electrode is higher than actuators with the doped ACET electrode. This inconsistency indicates that the three conductive particles improve electrode performance through different mechanisms. This inconsistency demonstrates that the introduction of some conductive particles can enhance the ordered lamellar void structure inside the electrode and specific capacitance, and the introduction of some particles can improve the cycle stability.