Stretchable Energy Storage Devices Research Articles

High-Performance Organic-Inorganic Hybrid Conductive Hydrogels for Stretchable Elastic All-Hydrogel Supercapacitors and Flexible Self-Powered Integrated Systems.

Conductive polymer hydrogels exhibit unique electrical, electrochemical, and mechanical properties, making them highly competitive electrode materials for stretchable high-capacity energy storage devices for cutting-edge wearable electronics. However, it remains extremely challenging to simultaneously achieve large mechanical stretchability, high electrical conductivity, and excellent electrochemical properties in conductive polymer hydrogels because introducing soft insulating networks for improving stretchability inevitably deteriorates the connectivity of rigid conductive domain and decreases the conductivity and electrochemical activity. This work proposes a distinct confinement self-assembly and multiple crosslinking strategy to develop a new type of organic-inorganic hybrid conductive hydrogels with biphase interpenetrating cross-linked networks. The hydrogels simultaneously exhibit high conductivity (2000 S m-1), large stretchability (200%), and high electrochemical activity, outperforming existing conductive hydrogels. The inherent mechanisms for the unparalleled comprehensive performances are thoroughly investigated. Elastic all-hydrogel supercapacitors are prepared based on the hydrogels, showing high specific capacitance (212.5 mF cm-2), excellent energy density (18.89 µWh cm-2), and large deformability. Moreover, flexible self-powered luminescent integrated systems are constructed based on the supercapacitors, which can spontaneously shine anytime and anywhere without extra power. This work provides new insights and feasible avenues for developing high-performance stretchable electrode materials and energy storage devices for wearable electronics.

High-Performance Organic-Inorganic Hybrid Conductive Hydrogels for Stretchable Elastic All-Hydrogel Supercapacitors and Flexible Self-Powered Integrated Systems.

Conductive polymer hydrogels exhibit unique electrical, electrochemical, and mechanical properties, making them highly competitive electrode materials for stretchable high-capacity energy storage devices for cutting-edge wearable electronics. However, it remains extremely challenging to simultaneously achieve large mechanical stretchability, high electrical conductivity, and excellent electrochemical properties in conductive polymer hydrogels because introducing soft insulating networks for improving stretchability inevitably deteriorates the connectivity of rigid conductive domain and decreases the conductivity and electrochemical activity. This work proposes a distinct confinement self-assembly and multiple crosslinking strategy to develop a new type of organic-inorganic hybrid conductive hydrogels with biphase interpenetrating cross-linked networks. The hydrogels simultaneously exhibit high conductivity (2000 S m-1), large stretchability (200%), and high electrochemical activity, outperforming existing conductive hydrogels. The inherent mechanisms for the unparalleled comprehensive performances are thoroughly investigated. Elastic all-hydrogel supercapacitors are prepared based on the hydrogels, showing high specific capacitance (212.5 mF cm-2), excellent energy density (18.89 µWh cm-2), and large deformability. Moreover, flexible self-powered luminescent integrated systems are constructed based on the supercapacitors, which can spontaneously shine anytime and anywhere without extra power. This work provides new insights and feasible avenues for developing high-performance stretchable electrode materials and energy storage devices for wearable electronics.

Integrated construction of stretchable supercapacitor with outstanding deformation stability and flame retardancy

The fast development of wearable electronics requires urgently stretchable energy storage devices, but conventional stretchable energy-storage devices suffer from poor dynamic deformation stability. The key is to create a new construction strategy of "electrode/electrolyte interface integration". Herein, we have proposed a clever strategy that combines layer-by-layer electrospinning with a self-selected vapor-phase polymerization (VPP) method to assemble the integrated stretchable supercapacitors (ISSCs). Furthermore, the interface stability enhancement mechanism is revealed through experimental and theoretical simulations, showing that the synergistic effect of molecular chain entanglement and mechanical meshing endows excellent anti-deformation stability of ISSCs. As a result, the as-assembled ISSCs deliver excellent dynamic deformation electrochemical stability with 99.5 % capacitance retention after 500 stretching cycles at strain and outstanding flame retardancy (limiting oxygen index (LOI) up to 48.1 % at a film thickness of only 0.22 mm). The innovative integrated design strategy endows a systematic construction plan for the scalable fabrication of wearable organic energy storage devices.

Recyclable liquid metal – Graphene supercapacitor

Because of their high electrical conductivity, fluidic deformability, self-healing properties, and the possibility of recycling, Ga-based liquid metal alloys like eutectic gallium indium (EGaIn) have tremendous potential as electrodes for stretchable energy storage devices. However, EGaIn droplets could never be used as electrodes in thin-film supercapacitors (SCs) at the desired micro/nano scale, because they rapidly coalesce into bulk EGaIn when contacting acidic/alkaline electrolytes. Here, we show that coating EGaIn droplets with only 0.08 wt% of reduced graphene oxide (GO) nanosheets tremendously improves their chemical stability. We fabricated binder-free GO-coated EGaIn nanocomposite electrodes that show excellent stability in a strong alkaline electrolyte. We demonstrated a symmetric soft-matter pseudo-SC with areal capacitances of 1200mF/cm2@0.3 mA/cm2 and 220mF/cm2@1mA/cm2, which is > 10 × compared to previous SCs based on bulk EGaIn. This SC retains 98.4 % of the initial capacitance after 4000 electrochemical cycles and exhibits comparable self-discharge rates to state-of-the-art flexible pseudo-SCs. Surprisingly, applying mechanical strain results in improved areal capacitance. We demonstrate rapid, laser-based fabrication of a wirelessly chargeable elastic film with an integrated energy harvesting antenna and energy-storage SC that can be used in wearable biomonitoring patches, and e-textiles. Finally, we demonstrate the recovery of the metals from the disposed of SCs through an electrowinning technique.

Scalable 2D/2D Assembly of Ultrathin MOF/MXene Sheets for Stretchable and Bendable Energy Storage Devices

AbstractScalable assembly of two dimensional (2D) lamellar nanomaterials for deformable films has potential in wearable energy storage devices, but overcoming the trade‐off in mechanical and energy storage properties is a challenge. Here, a blade‐coating strategy is reported to develop highly stretchable and bendable metal‐organic frameworks/large‐sized Ti3C2Tx MXene (MOF/LMX) composite films on the pre‐stretched elastomer substrates. The LMX sheets serve as conductive scaffolds for loading the small‐sized ultrathin MOF sheets (SUMOFs), resulting in an improved tensile strength (≈97 MPa) of the films, which guarantees their structural integrity when forming a wavy structure on a relaxed substrate. In addition, SUMOFs incorporated in‐between LMX layers not only expose active redox sites by mitigating the intrinsic self‐restacking of MOF but also accelerate the electron transfer in the redox reaction process revealed through the density functional theory calculations. As a result, the composite films deliver high electrical conductivity (3244 S cm−1) and energy storage capability (1238 F g−1). When assembled into an asymmetric supercapacitor device, it also exhibits stable performances under different bending and stretching states. Thus, the development of conducting and deformable MOF‐based films with high mechanical, electrical, and energy storage properties enables their potential commercial applications for wearable electronics.

Stretchable microbatteries and microsupercapacitors for next-generation wearable electronics

Stretchable energy-storage devices are required to power next-generation wearable electronics intimately integrated with the human body. The microbatteries and microsupercapacitors represent promising candidates featuring small footprints and facile system integration. This perspective reviews common strategies to convert conventional rigid devices into stretchable forms. Several prototype soft electronic systems are presented utilizing microbatteries and microsupercapacitors as power sources. We discuss the current challenges and perspectives of the stretchable microbattery and microsupercapacitor. Stretchable forms of miniaturized energy-storage devices often show a significant trade-off between mechanical deformability and electrochemical performances, which present attractive opportunities for the material and engineering community.

An intrinsically stretchable symmetric organic battery based on plant-derived redox molecules

A plant-based, stretchable organic battery was developed by formulating a quaternary biocomposite electrode that possesses high electrical and ionic conductivities, charge storage capacity of 6.8 mA h cm−3, and tensile stretchability over 300%.

3D-Printed Silicone Substrates as Highly Deformable Electrodes for Stretchable Li-Ion Batteries.

Stretchable energy storage devices receive a considerable attention at present due to their growing demand for powering wearable electronics. A vital component in stretchable energy storage devices is its electrode which should endure a large and repeated number of mechanical deformations during its prolonged use. It is crucial to develop a technology to fabricate highly deformable electrode in an easy and an economic manner. Here, the fabrication of stretchable electrode substrates using 3D-printing technology is reported. The ink for fabricating it contains a mixture of sacrificial sugar particles and polydimethylsiloxane resin which solidifies upon thermal curing. The printed stretchable substrate attains a porous structure after leaching the sugar particles in water. The resulting printed porous stretchable substrates are then utilized as electrodes for Li-ion batteries (LIBs) after loading them with electrode materials. The batteries with stretchable electrodes exhibit a decent electrochemical performance comparable to that of the conventional electrodes. The stretchable electrodes also exhibit a stable electrochemical performance under various mechanical deformations and even after several hundreds of stretch/release cycles. This work provides a feasible route for constructing LIBs with high stretchability and enhanced electrochemical performance thereby providing a platform for realizing stretchable batteries for next generation wearable electronics.

(Invited, Digital Presentation) 3D Printing of Flexible and Wearable Supercapacitors

Flexible and wearable electronics have recently emerged as a potential solution for next-generation electronics for healthcare, sports, transport, military, soft robotics, artificial intelligence, the internet of things, and other applications. However, these devices are still at a fledgling stage due to the use of traditional manufacturing processes, lack of compatible power supply, poor commercialization capabilities, and integration problems. Here, we present 3D printing approaches for developing batteries and supercapacitors for flexible electronic applications. Such manufacturing techniques can revolutionize the rapidly growing field of flexible and wearable electronics due to their several attributes like; rapid production, simplicity, capability to produce size and shape versatile patterns, computer-aided design, user control, and environmental friendliness.(1-4) Different aspects of 3D printed supercapacitors (such as; device design, ink preparation of electrode/ electrolyte components, rheology control of inks, surface modification to get good print quality, electrochemical performance of printed devices, and flexibility analysis) will be discussed in detail with a focus on future requirements.References Sundriyal P, Bhattacharya S. Scalable micro-fabrication of flexible, solid-state, inexpensive, and high-performance planar micro-supercapacitors through inkjet printing. ACS Applied Energy Materials. 2019;2(3):1876-90.Sundriyal P, Bhattacharya S. Inkjet-printed electrodes on A4 paper substrates for low-cost, disposable, and flexible asymmetric supercapacitors. ACS Applied Materials & Interfaces. 2017;9(44):38507-21.Sundriyal P, Bhattacharya S, editors. 3-D Printed Electrode Materials for Low-Cost, Flexible, and Stretchable Energy Storage Devices. ECS Meeting s; 2019: IOP Publishing.Sundriyal P, Bhattacharya S. Textile-based supercapacitors for flexible and wearable electronic applications. Scientific reports. 2020;10(1):1-15.

Mini Review of Reliable Fabrication of Electrode under Stretching for Supercapacitor Application.

Currently, there is an increasing demand for portable and wearable electronics. This has necessitated the development of stretchable energy storage devices, while simultaneously maintaining performance. Hence, the electrodes and electrolyte materials used in stretchable supercapacitors should be robust under severe mechanical deformation. Polymers are widely used in the fabrication of stretchable supercapacitors. It is not only crucial to choose good polymer candidates with inherent advantages, but it is also important to design suitable polymer materials for both electrodes and electrolytes. This mini-review explains the concept of stretchable supercapacitors, the theoretical background of polymer-based electrodes for supercapacitors, and the fabrication strategies of stretchable electrodes for supercapacitors. Finally, we present the drawbacks and areas that still need to be developed.

Supramolecular Gel-Derived Highly Efficient Bifunctional Catalysts for Omnidirectionally Stretchable Zn-Air Batteries with Extreme Environmental Adaptability.

Most existing stretchable batteries can generally only be stretched uniaxially and suffer from poor mechanical and electrochemical robustness to withstand extreme mechanical and environmental challenges. A highly efficient bifunctional electrocatalyst is herein developed via the unique self‐templated conversion of a guanosine‐based supramolecular hydrogel and presents a fully integrated design strategy to successfully fabricate an omnidirectionally stretchable and extremely environment‐adaptable Zn–air battery (ZAB) through the synergistic engineering of active materials and device architecture. The electrocatalyst demonstrates a very low reversible overpotential of only 0.68 V for oxygen reduction/evolution reactions (ORR/OER). This ZAB exhibits superior omnidirectional stretchability with a full‐cell areal strain of >1000% and excellent durability, withstanding more than 10 000 stretching cycles. Promisingly, without any additional pre‐treatment, the ZAB exhibits outstanding ultra‐low temperature tolerance (down to −60 °C) and superior waterproofness, withstanding continuous water rinsing (>5 h) and immersion (>3 h). The present work offers a promising strategy for the design of omnidirectionally stretchable and high‐performance energy storage devices for future on‐skin wearable applications.

Toward stretchable batteries: 3D-printed deformable electrodes and separator enabled by nanocellulose

The needs for stretchable batteries surge as wearable and epidermal electronics emerge. The development of stretchable batteries, however, remains a grand challenge, as the battery components are intrinsically brittle and fracture easily under mechanical loading. Existing efforts to increase the stretchability of battery components often involve complex fabrication processes and thus are not viable for scalable and cost-effective manufacturing. To address this challenge, herein a facile yet effective strategy is developed to fabricate stretchable electrodes and separator for Li-ion batteries using extrusion-based 3D printing of active materials mixed with nanofibrillated cellulose. The resulting electrodes and separator can achieve reversible stretchability of 50%. After 50 stretching cycles, the resistance of the electrodes under 50% stretch only increases by 3%. The origin of the exceptional mechanical and electrical performances of the 3D-printed battery components is twofold: (i) excellent deformability enabled by the 3D-printed serpentine structure at the component level; (ii) the robust nanoscale structure due to the high aspect ratios of nanofibrillated cellulose and carbon nanotubes and the strong interactions between nanofibrillated cellulose and carbon nanotubes or among the individual cellulose fibers at the material structure level. The facile 3D printing of the patterned electrodes/separator leads to low-cost manufacturing of high-performance stretchable Li-ion batteries, demonstrating its promising potential to enable stretchable energy storage devices for wearable and epidermal electronics.

High-Performance-Integrated Stretchable Supercapacitors Based on a Polyurethane Organo/Hydrogel Electrolyte.

Stretchable supercapacitors (SSCs) are promising energy storage devices for emerging wearable electronics. However, the low-energy density and poor deformation performance are still a challenge. Herein, an amphiphilic polyurethane-based organo/hydrogel electrolyte (APUGE) with a H2O/AN-in-salt (H2O/AN-NaClO4) is prepared for the first time. The as-prepared APUGE shows a wide voltage window (∼2.3 V), good adhesion, and excellent resilience. In addition, the intrinsically stretchable electrodes are prepared by coating the activated carbon slurry onto the PU/carbon black/MWCNT conductive elastic substrate. Based on the strong interface adhesion of the PU matrix, the as-assembled SSC delivers high-energy density (5.65 mW h cm-3 when the power density is 0.0256 W cm-3) and excellent deformation stability with 94.5% capacitance retention after 500 stretching cycles at 100% strain. This fully integrated construction concept is expected to be extended to multisystem stretchable metal ion batteries, stretchable lithium-sulfur batteries, and other stretchable energy storage devices.

Study of fabric knitted using Ag-coated filaments to form stretchable electrodes for use in energy storage applications

ABSTRACT Stretchable and flexible electrodes are desirable for use in mobile and wearable devices. When one surface of a fabric is non-conductive and the other surface is electrochemically active, such a fabric could potentially be used as an electrode in an electrochemical application without a separator because the non-conductive surface would prevent short circuits between the electrodes. In this study, a stretchable fabric with a conductive surface that has been knitted using Ag-coated filaments was cycled in aqueous (alkaline, acidic, and neutral) and non-aqueous (ionic liquid) electrolytes to study their electrochemical behaviors for their usability as energy storage devices. After study via cyclic voltammetry, KOH solution was selected as the most appropriate electrolyte among the four considered because the fabric showed stable oxidation and reduction peaks in this electrolyte after repetitive cycling. The Ag-based fabric electrode was also found to evolve (became stable) in this electrolyte. Electrochemical (cyclic voltammogram) and non-electrochemical (X-ray diffraction, scanning electron microscope, energy dispersive X-ray spectroscopy) characterization of the electrode were carried out. The cycling of stretchable fabric was stopped at the oxidized and reduced potential in KOH electrolyte in order to characterize the crystalline, morphological, and compositional structure of the electrode as dependent on the applied potential. The capacitances of the electrode remained similar when the timescale was increased 40-fold, indicating that the electrode has a high power density. The reaction between the fabric and OH− electrolyte was found to proceed as a ‘mixture’ of a surface- and a diffusion-controlled mechanism. The areal and specific capacitances of the electrode were found to be 46 mF cm−2 and 36 F g−1, respectively. The stretchable fabric with Ag-coated filaments could potentially be used as an electrode in a hydroxide-based electrolyte for stretchable and flexible energy storage devices.

Crumpled MXene Electrodes for Ultrastretchable and High-Area-Capacitance Supercapacitors.

In spite of the excellent electrical and electrochemical properties, two-dimensional transition metal carbide (MXene) is often limited by the high stiffness for the direct implementation in next-generation stretchable and wearable energy storage devices. The improved deformability has been achieved in ultrathin composite electrodes utilizing additives that substantially reduce the specific capacitance. Here, we demonstrate an ultrastretchable and high-performing supercapacitor based on MXene electrodes with crumpled textures. After screening on the thickness, the crumpled MXene film of ∼3 μm in thickness is identified as the optimal choice to mitigate the crack formations under large and repetitive mechanical strains. The as-prepared symmetric supercapacitor, therefore, demonstrates a high specific capacitance of ∼470 mF cm-2, ultrahigh stretchability up to 800% area strain, and >90% retention of the initial capacitance after 1000 stretch-relaxation cycles. The developments offer an attractive avenue to design stretchable electrodes based on various two-dimensional nanomaterials and their composites.

A high-strength and ultra-stable halloysite nanotubes-crosslinked polyacrylamide hydrogel electrolyte for flexible zinc-ion batteries

Zinc-ion batteries (ZIBs) promises to satisfy the development of flexible and wearable electronic devices. However, it remains a challenge to render the electrolyte of flexible ZIBs operating in harsh conditions during daily use, while maintaining their stability and durability. Herein, we report a high-strength and ultra-stable hydrogel electrolyte by crosslinking the halloysite nanotubes (HNTs) modified by 3-Methacryloxypropyltrimethoxysilane (MPS) with polyacrylamide (PAM), denoted as M-HNTs/PAM. The M-HNTs/PAM hydrogel exhibits a large strain of 1200% with a strength of 49 kPa. The designed flexible Zn/Zn symmetric batteries based on M-HNTs/PAM hydrogel electrolyte enable stable Zn plating and stripping over 1200 h at 4.4 mA cm−2 and 1.1 mA h cm−2. The flexible ZIBs based on M-HNTs/PAM hydrogel electrolyte possess outstanding cycling stability and great capacity retention of 92.7% after 1000 cycles at 10 C. Moreover, the flexible ZIBs can overcome violent tests of bending, folding, hammering, and even poking. It opens up new perspectives to utilize clay minerals and provides new valuable insights for durable wearable and stretchable energy storage devices.

A Quest for Sustainable Energy: From Nanoscale Energy Generators to Green Batteries and Supercapacitors

Batteries run just about everything portable in our lives such as smartphones, tablets, computers, etc. While we have become accustomed to the rapid improvement of portable electronics, the slow development of batteries is holding back technological progress. This has put energy storage research as one of the most explored areas in chemistry and materials science. In this talk, I will discuss innovative techniques for the fabrication of energy-storage devices with new features not possible with current state-of-the-art technology. Several examples will be given, ranging from smaller and more powerful batteries to completely flexible and stretchable energy-storage devices as well as green and biodegradable batteries. Special emphasis will be placed on supercapacitors that are gradually changing our lives in many ways; they are also revolutionizing a breadth of industries including transport, aerospace and consumer electronics. In addition, our work holds promise for a new generation of pacemakers that could save millions of lives by monitoring and controlling the heart rhythms of the patients. While current pacemakers rely on primary batteries for their power, their limited lifespan make replacement surgery unavoidable, putting patients at risk of serious and life-threatening infection. The talk will present ultrathin power sources we have recently developed for harvesting energy from the human body as a promising approach for implantable medical devices that may not need to be replaced during the lifetime of the patient.The second part of my talk will be dedicated to our recent work on nanogenerators that convert ambient mechanical energy into electricity, offering an alternative for sustainably driving portable electronics. Using 3D extrusion printing, our team developed a prototype nanogenerator to create electricity when it comes into contact with snow. The device could potentially be integrated with solar panels to ensure continuous power supply in areas with frequent snowfall. It is also used as a smartwatch for tracking winter sports, such as skiing, to more precisely assess and improve an athlete’s performance when running, walking or jumping. We utilized a similar technology for designing and building an electronic skin (e-skin) with functionalities and mechanical properties that mimic the natural skin. Unlike current research in this area where tethering to a large battery unit seems inevitable, the new e-skin contains integrated network of energy efficient sensors that create their own charge by touching the skin. This technology can be used to monitor vital signs and chronic medical conditions and may have great implications in robotics, prosthetics, and human-computer interface.These discoveries were made possible through the development of new functional nanomaterials with interesting and potentially useful characteristics such as optical, structural and electrochemical properties. At the forefront of these materials is graphene that was once established as the thinnest, strongest and most conductive material and today it continues to attract much attention in the scientific community and triggers significant industrial interest. The last part of my talk will discuss the efforts our team is taking to lead the transition of graphene technology from the lab to the marketplace through a UCLA spinoff known as Nanotech Energy, Inc. After 6 years of development, current production capacity has reached one metric tons per year, which catalyzed our ability to transform various graphene discoveries into commercial products, with the very first demonstrations in EMI shielding materials, printed electronics and more powerful batteries and supercapacitors. Figure 1

Fully integrated design of intrinsically stretchable electrodes for stretchable supercapacitors

Constructing the intrinsically stretchable electrodes can fundamentally solve the problems of complex assembly process and insufficient structural stability of stretchable energy-storage devices. Further considering the practical needs, it is very necessary to realize the coordinated improvement of electrochemical performance, deformation performance and fire safety. Here, an intrinsically stretchable device with homogeneous configuration based on elastic flame-retardant matrix was proposed for the first time. In detail, a high-performance stretchable asymmetric supercapacitor was realized through using a conductive elastomer prepared by compounding poly(3,4-ethylenedioxythiophene) nanofibers into fluororubber (PEDOT NFs@FKM) as positive electrode, the Ag nanowires/fluororubber conductive elastic substrate coated with PDAA nanoparticles (PDAA@Ag NWs/FKM) as the negative electrode, and the fluororubber-based porously fibrous membrane prepared by electrospinning (pFKM) as the quasi-solid electrolyte substrate. Due to this fully integrated design, the newly developed supercapacitor is high stretchable and simultaneously deliver high energy density (11.8 mWh cm−3 when the power density is 0.0693 W cm−3). During 300 cycles of stretching at 50% stretch ratio, the device maintains good electrochemical performance. This fully integrated construction concept of this work is expected to be extended to stretchable lithium-ion battery, stretchable lithium sulfur batteries and other systems.

Stretchable Energy Storage Devices Based on Carbon Materials.

Stretchable energy storage devices are essential for developing stretchable electronics and have thus attracted extensive attention in a variety of fields including wearable devices and bioelectronics. Carbon materials, e.g., carbon nanotube and graphene, are widely investigated as electrode materials for energy storage devices due to their large specific surface areas and combined remarkable electrical and electrochemical properties. They can also be effectively composited with many other functional materials or designed into different microstructures for fabricating stretchable energy storage devices. This review summarizes recent advances toward the development of carbon-material-based stretchable energy storage devices. An overview of common carbon materials' fundamental properties and general strategies to enable the stretchability of carbon-material-based electrodes are presented. The performances of the as-fabricated stretchable energy storage devices including supercapacitors, lithium-ion batteries, metal-air batteries, and other batteries are then carefully discussed. Challenges and perspectives in this emerging field are finally highlighted for future studies.

Design and analysis of Cu circuit for stretchable electronic circuits using finite element analysis

Stretchable electronic devices are desirable for the next application of electronic devices such as stretchable sensors, stretchable energy storage devices, and humanmachine interfaces. Also, stretchable electronic systems require a stretchable metal circuit on the elastomeric substrate for electrical connection to components. The stretchable circuits fabricated by Cu foil lamination on the thermoplastic polyurethane (TPU) film are investigated with various zigzag-patterned circuit designs. The various circuit designs are simulated by finite element analysis (FEA) for fatigue life prediction and the simulation results are compared with experimental results. The 6 types of zigzag-shaped circuit designs with different corner patterns are investigated. The thicknesses of the Cu electrode and TPU substrate are 18 μm and 50 μm, respectively. The stretchability of Cu stretchable circuits is evaluated by the uniaxial tensile test with 10% elongation. Also, the equivalent plastic strain is calculated for fatigue life prediction. The number of stretch cycles to failure increased as decreasing the equivalent plastic strain obtained by FEA. The tendency of crack propagation and fatigue life prediction are well agreed with FEA results. Thus, it is considered that modifying the circuit patterns of the strain concentration area is the most important to enhance the mechanical reliability of stretchable circuits.