Effect of porosity and tortuosity of electrodes on carbon polymer soft actuators

Abstract

This work presents an electro-mechanical model and simulation of ionic electroactive polymer soft actuators with a porous carbon electrode, polymer membrane, and ionic liquid electrolyte. An attempt is made to understand the effects of specific properties of the porous electrodes such as porosity and tortuosity on the charge dynamics and mechanical performance of the actuator. The model uses porous electrode theory to study the electrochemical response of the system. The mechanical response of the whole laminate is attributed to the evolution of local stresses caused by diffusion of ions (diffusion-induced stresses or chemical stresses). The model indicates that in actuators with porous electrode, the diffusion coefficient of ions, conductivity of the electrodes, and ionic conductivity in both electrodes and separator are altered significantly. In addition, the model leads to an obvious deduction that the ions that are highly active in terms of mobility will dominate the whole system in terms of resulting mechanical deformation direction and rate of deformation. Finally, to validate the model, simulations are conducted using the finite element method, and the outcomes are compared with the experimental data. Significant effort has been put forward to experimentally measure the key parameters essential for the validation of the model. The results show that the model developed is able to well predict the behavior of the actuator, providing a comprehensive understanding of charge dynamics in ionic polymer actuator with porous electrodes.

Soft parallel manipulator fabricated by additive manufacturing

“…The model uses the Butler-Volmer equation [66] to represent the faradaic current due to redox reactions and the current plateaus representing double layer charging effect are described using phenomenological double layer capacitive relation exhibiting a linear dependence of the charge stored with the width of the potential window [58,67,68]. Previously we have reported multiphysics modelling of coupling electrochemical and mechanical response for carbon-based actuator ionic actuators [69], with purely capacitive behaviour taken into consideration and here the model is modified to also include the redox behaviour.…”

High-Performance All-Gel-State Nano-Biopolymer Artificial Muscles Enabled by Macromolecularly Interconnected Conductive Microporous Chitosan and Graphene Loaded Carbon Nanosheet Based Ionic Electrolyte Membrane

“…In the past study, more efforts was devoted to electrodes with high conductivity of gel-based polymer composite actuators, which was based on the latest derivatives of carbon-based nanomaterials. 17,18 However, according to the structure composition of nano-polymer actuator, the effect of interlayer electrolyte layer on the electromechanical properties is significantly greater than that of the electrode layer. This is because the thickness of the middle electrolyte layer is significantly larger than the electrode layer.…”