Low-temperature soft electrochemical actuator based on hierarchically structured polypyrrole membranes for subzero operation

Abstract

Low-temperature-resistant actuating materials are highly desirable for enabling exploration in extreme environments, such as polar regions or outer space. However, most electrochemically active polymers experience severe performance degradation at subzero temperatures due to impaired ionic and electronic transport. Consequently, achieving temperature-tolerant electrochemical actuation remains a significant challenge. Herein, a soft electrochemical actuator is developed based on a self-supporting polypyrrole membrane featuring hollow vesicles structures with coral-like rods. This hierarchical structure ensures a continuous conductive network and facilitates rapid ion diffusion, enabling stable actuation performance even at −24°C. The actuator demonstrates remarkable performance, including large actuation strain (∼37%), low energy consumption per unit strain (0.12 mW cm⁻² %⁻¹), high coulombic efficiency (1.76 mC mg⁻¹ deg⁻¹), and a substantial deformation angle of ∼98°. These results highlight the significance of morphological design in enhancing electrochemical responsiveness under extreme conditions. This work offers a promising strategy for developing next-generation low-temperature electrochemical actuators.