Mechanical deformation effects on ion conduction in stretchable polymer electrolytes

Abstract

Flexible and stretchable energy storage devices, including batteries, supercapacitors, and ionic piezoelectrics, have garnered substantial research interest in recent years to address a wide range of applications such as smart textiles and medical implants. These devices are intended to undergo mechanical deformation, and the impact of deformation on electrochemical performance is not well understood. One important area of focus is studying how mechanical deformation influences ion conduction in polymer electrolytes. In this work, a dual theoretical and experimental approach is taken to further evaluate this phenomenon. A stretchable solid polymer electrolyte film subjected to tensile deformation (approximately 48% strain), through which ion diffusion occurs, is analyzed using a continuum approach treating ion diffusion and mechanical deformation as coupled. Thermodynamic laws are applied to obtain governing multiphysics equations accounting for large deformation mechanics and material nonlinearity. The theoretical solution obtained demonstrates how through-plane ionic conductivity changes when the polymer is subjected to stretching. Evolutionary materials deformation of the polymer electrolyte is considered to elucidate the underlying driving physical mechanisms of ion conduction. An experiment was also conducted to measure change in through-plane ionic conductivity with applied uniaxial strain in a sample of polyethylene oxide (PEO), a material commonly used as the electrolyte in solid polymer electrolyte lithium ion batteries. The experimental results show a greater than 1600% ionic conductivity enhancement for approximately 48% strain. The theoretical and experimental results are in good agreement and show that ion conduction is enhanced with increasing strain following an exponential function for a PEO electrolyte.

Flexible Artificial Synapses Based on Field Effect Transistors: From Materials, Mechanics towards Applications

“…In contrast to previous reports, the ion conductivity decreased with an increase in the mechanical strain. [55,56] The decrease in the ion-gel film resistance was due to the highly deformation-dependent ion migration in the ion-gel, which is consistent with the mechanical deformation effect on the biological nervous system (Figure 5e). [57][58][59] This study initially utilized a mechanical deformation method to adjust synaptic performance, while future research should further explore the development of actual applications.…”

General Fabrication of 3D Hierarchically Structured Bamboo-like Nitrogen-Doped Carbon Nanotube Arrays on 1D Nitrogen-Doped Carbon Skeletons for Highly Efficient Electromagnetic Wave Energy Attenuation

“…At a high frequency, the eddy effect usually occurred in the magnetic metal−carbon composites, leading to negative values of μ″ and tan δ m . 64 Nevertheless, the magnetic losses of 3D HMCNTs are greatly lower than their dielectric losses, revealing that the EMW attenuation performances of our designed 3D structures are mainly contributed by their dielectric losses. In addition, the specific surface area of samples is also one of the crucial factors for the EMW loss.…”

“…The low magnetic losses are attributed to the large coercivities. , It is worth noticing that the μ″ and tan δ m values of HMCNTs are negative at a high frequency. At a high frequency, the eddy effect usually occurred in the magnetic metal–carbon composites, leading to negative values of μ″ and tan δ m . Nevertheless, the magnetic losses of 3D HMCNTs are greatly lower than their dielectric losses, revealing that the EMW attenuation performances of our designed 3D structures are mainly contributed by their dielectric losses.…”

Stretchable Transistor‐Structured Artificial Synapses for Neuromorphic Electronics

“…[30] The PUU polymer elastomer has a low glass transition temperature, high chain segmental motion (ion dissociation and conduction), excellent dielectric properties, and high mechanical stretchability-an ideal dielectric material for stretchable synaptic transistors based on the ion conduction mechanism. [102][103][104] The devices have successfully emulated biological synaptic functions, including excitatory and inhibitory behaviors, STP, and filtering characteristics. During stretching tests, the devices exhibited excellent mechanical stretchability such that both the transistor characteristics and the synaptic functions remained stable even after experiencing 400 stretching cycles by 25% strain.…”