High-performance biocompatible nano-biocomposite artificial muscles based on a renewable ionic electrolyte made of cellulose dissolved in ionic liquid

In this work, high-performance biocompatible nano-biocomposite artificial muscles were developed via various thicknesses of renewable microporous ionic electrolytes (ICEs) made of natural biopolymer cellulose dissolved in ionic liquid with excellent ionic conductivity and flexibility. The changing thickness experiments illustrated that 0.7 mm thick ICEs could deliver outstanding areal capacitance of 44.708 mF cm⁻² and ionic conductivity of 79.7 μS cm⁻¹, as well as minimum resistance of 1.61 Ω. The current density changed from 1 to 10 Ag⁻¹, and improvements were achieved in energy density (from 3.88 to 21.25 Wh kg⁻¹) and power density (from 2.63 to 5.51 KW kg⁻¹). The voltage window widened from 0.5 to 1 V, and improvements were gained in energy density (from 4.13 to 22.01 Wh kg⁻¹) and power density (from 1.25 to 2.81 KW kg⁻¹). Moreover, good flexibility of 0.7 mm thick ICE with porosity of 89.61% and elastic modulus of 74.38 MPa was discovered. Electromechanical experiments demonstrated from the above results that the maximum peak displacement with 0.3 mm ICE was 5.33 mm at 5 V 0.02 Hz sine wave voltage, and the maximum displacement and force with 0.7 mm ICE was 17.44 mm and 5.93 mN at 5 V DC voltages. These findings suggest that the explored excellent ionic conductivity and flexibility of ICEs holds great promise for the further study of high-performance green actuators. (paper)