Flexible Solid State Research Articles

Supercapacitor devices based as SILAR synthesized ytterbium sulfide @ graphene oxide nanocomposite flexible thin film electrodes

• For first time Yb 2 S 3 , GO and GO/Yb 2 S 3 composite films are prepared by SILAR method. • The GO/Yb 2 S 3 composite thin film showed maximum Cs of 376 Fg −1 at 5 mV s −1 scan rate. • The FSS-SSC device showed Cs 58F g −1 , E. D. 23 Wh kg −1 and P. D. 0.43 kW kg −1. • The FSS-ASC device showed Cs 92F g −1 , E. D. 42 Wh kg −1 and P. D. 0.84 kW kg −1. • Glowing of 211 red LEDs panel showed the practical application of both devices. Ytterbium sulfide (Yb 2 S 3 ), graphene oxide (GO), and graphene oxide/ytterbium sulfide (GO/Yb 2 S 3 ) composite thin films were synthesized by binder-free successive ionic layer adsorption and reaction (SILAR) method. Formation of Yb 2 S 3 , GO and GO/Yb 2 S 3 composite thin films was confirmed by XRD and XPS techniques. Surface morphology and particle size of these films were observed through FE-SEM and TEM analyses. All thin films showed hydrophilic nature. The Yb 2 S 3 , GO and GO/Yb 2 S 3 composite thin films exhibited the maximum specific capacitance of 181, 193 and 376 F g −1 , respectively in 1 M Na 2 SO 4 electrolyte at scan rate of 5 mV s −1 . The flexible solid state supercapacitor (FSS-SSC) symmetric device was fabricated with GO/Yb 2 S 3 composite electrodes as an anode and a cathode and a flexible solid state asymmetric supercapacitor (FSS-ASC) device were fabricated with GO/Yb 2 S 3 as an anode and MnO 2 as a cathode electrode with the PVA-Na 2 SO 4 gel electrolyte. The FSS-SSC device showed specific capacitance 58 F g −1 , energy density 23 Wh kg −1 and power density 0.43 kW kg −1 . The FSS-ASC device showed specific capacitance 92 F g −1 , energy density 42 Wh kg −1 and power density 0.84 kW kg −1 . Both FSS-SSC and FSS-ASC devices showed coulombic efficiency of 88 and 79% for 10,000 GCD cycles, respectively. The FSS-ASC device showed better performance than the FSS-SSC device. The FSS-ASC device showed better performance than the FSS-SSC device.

Flexible Solid-State Supercapacitors with Outstanding Capacitive Performance Enabled by N/B-Codoped Porous Carbon Nanosheets

Flexible Solid-State Supercapacitors with Outstanding Capacitive Performance Enabled by N/B-Codoped Porous Carbon Nanosheets

In-Situ Growth of Urchin Manganese Sulfide Anchored Three-Dimensional Graphene (γ-MnS@3DG) on Carbon Cloth as a Flexible Asymmetric Supercapacitor.

In energy storage-device it is highly crucial to develop durable electrode materials having high specific capacitance and superior energy density without disturbing its inherent flexibility. Herein, we demonstrate three-dimensional graphene oxide decorated monodispersed hollow urchin γ-MnS (γ-MnS@3DG) via proficient one-step solvothermal method. The designed material delivers a remarkable capacitance of 858 F g-1 at 1 A g-1. A flexible solid state asymmetric supercapacitor (ASCs) device assembled using surface activated carbon cloth (CC) decorated with γ-MnS@3DG as positive and three-dimension graphene on carbon cloth (3DG@CC) as negative electrode, (γ-MnS@3DG//3DG). The device delivers 26 Wh kg-1 energy density at power density 500 W kg-1 @ 1A g-1 and retains favorable energy density 17.8 Wh kg-1 at an ultrahigh power density of 1500 W kg-1@3 A g-1. This carbon embedded transition-metal sulfide (TMS) based ASC demonstrates eminent mechanical flexibility under rigorous bending states maintaining invariant performance.

Lithium-Rich Anti-perovskite Li2OHBr-Based Polymer Electrolytes Enabling an Improved Interfacial Stability with a Three-Dimensional-Structured Lithium Metal Anode in All-Solid-State Batteries.

All-solid-state lithium-metal batteries, with their high energy density and high-level safety, are promising next-generation energy storage devices. Their current performance is however compromised by lithium dendrite formation. Although using 3D-structured metal-based electrode materials as hosts to store lithium metal has the potential to suppress the lithium dendrite growth by providing a high surface area with lithiophilic sites, their rigid and ragged interface with solid-state electrolytes is detrimental to the battery performance. Herein, we show that Li2OHBr-containing poly(ethylene oxide) (PEO) polymer electrolytes can be used as a flexible solid-state electrolyte to mitigate the interfacial issues of 3D-structured metal-based electrodes and suppress the lithium dendrite formation. The presence of Li2OHBr in a PEO matrix can simultaneously improve the mechanical strength and lithium ion conductivity of the polymer electrolyte. It is confirmed that Li2OHBr does not only induce the PEO transformation of a crystalline phase to an amorphous phase but also serves as an anti-perovskite superionic conductor providing additional lithium ion transport pathways and hence improves the lithium ion conductivity. The good interfacial contact and high lithium ion conductivity provide sufficient lithium deposition sites and uniform lithium ion flux to regulate the lithium deposition without the formation of lithium dendrites. Consequently, the Li2OHBr-containing PEO polymer electrolyte in a lithium-metal battery with a 3D-structured lithium/copper mesh composite anode is able to improve the cycle stability and rate performance. The results of this study provide the experimental proof of the beneficial effects of the Li2OHBr-containing PEO polymer electrolyte on the 3D-structured lithium metal anode.

Transport Properties of Flexible Composite Electrolytes Composed of Li1.5Al0.5Ti1.5(PO4)3 and a Poly(vinylidene fluoride-co-hexafluoropropylene) Gel Containing a Highly Concentrated Li[N(SO2CF3)2]/Sulfolane Electrolyte.

Flexible solid-state electrolyte membranes are beneficial for feasible construction of solid-state batteries. In this study, a flexible composite electrolyte was prepared by combining a Li+-ion-conducting solid electrolyte Li1.5Al0.5Ti1.5(PO4)3 (LATP) and a poly(vinylidene fluoride-co-hexafluoropropylene) (PVDF–HFP) gel containing a highly concentrated electrolyte of Li[N(SO2CF3)2] (LiTFSA)/sulfolane using a solution casting method. We successfully demonstrated the operation of Li/LiCoO2 cells with the composite electrolyte; however, the rate capability of the cell degraded with increasing LATP content. We investigated the Li-ion transport properties of the composite electrolyte and found that the gel formed a continuous phase in the composite electrolyte and Li-ion conduction mainly occurred in the gel phase. Solid-state 6Li magic-angle spinning NMR measurements for LATP treated with the 6LiTFSA/sulfolane electrolyte suggested that the Li+-ion exchange occurred at the interface between LATP and 6LiTFSA/sulfolane. However, the kinetics of Li+ transfer at the interface between LATP and the PVDF–HFP gel was relatively slow. The interfacial resistance of LATP/gel was evaluated to be 67 Ω·cm2 at 30 °C, and the activation energy for interfacial Li+ transfer was 39 kJ mol–1. The large interfacial resistance caused the less contribution of LATP particles to the Li-ion conduction in the composite electrolyte.

Enhanced specific energy of silver-doped MnO2/graphene oxide electrodes as facile fabrication symmetric supercapacitor device

The present work is about the preparation of silver (Ag)-doped manganese oxide (MnO2)/graphene oxide (GO) composite thin films are deposited by a facile and binder-free successive ionic layer adsorption and reaction (SILAR) method for the first time. The Brunauer-Emmett-Teller (BET) study revealed the nanosheets of MnO2–Ag3/GO exhibit high specific surface area of 192 m2 g−1. The tailored flower-like morphology and interconnected nanosheets of MnO2–Ag3/GO electrodes achieved high electrochemical performance. The maximum specific capacitance (Cs) of 877 F g−1 at the scan rate of 5 mV s−1 is obtained for MnO2–Ag3/GO electrode tested in 1 M sodium sulfate (Na2SO4) electrolyte with capacity retention of 94.57% after 5000 cycling stability. The MnO2–Ag3/GO composite-based flexible solid state symmetric supercapacitor (FSS-SSC) device delivered Cs as 164 F g−1 with specific energy of 57 Wh kg−1 at specific power of 1.6 kW kg−1 and capacitive retention of 94% after 10,000 cycles.

Preparation of a self-healing polyaniline-based gel and its application as a healable all-in-one capacitor

Polyaniline (PANI) prepared by polymerization methods is fragile due to its rigid structure. The preparation of PANI with desirable flexible performance and good ductility still remains a challenge. Here, a self-healing conductive polyacrylamide (PAM)/PANI gel (PPG) with sandwich structure is reported. The surface of PPG is composed of interpenetrating network of conductive PANI and flexible PAM through dynamic hydrogen bonds. PPG exhibits outstanding mechanical property with remarkable tensile strength (0.342 MPa) and elongation at break (277%), as well as efficient self-healing ability. Thus, PPG makes up for the flexible requirement of PANI and can be developed for potential application as an all-in-one solid-state capacitor with high performance. The flexible solid-state capacitor delivers a large capacitance (473 mF/cm2) and extraordinary self-healing performance. This work may provide new insight into the design of flexible PANI and a practical strategy to fabricate mechanically and electrochemically robust gel.

N-doped reduced graphene oxide (rGO) wrapped carbon microfibers as binder-free electrodes for flexible fibre supercapacitors and sodium-ion batteries

In this study, N-doped reduced graphene oxide (rGO) wrapped carbon micro fibres (CFs) were synthesized by one-step high temperature pyrolysis method. Free-standing binder-free electrodes of N-doped rGO on CF were fabricated to apply in extended flexible fibrous supercapacitors and sodium-ion batteries (NIBs). The results showed that the attachment of N-doped graphene onto CF led to high electrochemical capacitance properties. The micro-fibre electrodes showed high performance supercapacitor behaviour of 18.7 F cm−3 at a current density of 1 A cm−3 as a flexible solid-state energy storage device. In parallel with the supercapacitance properties, the micro-fibre electrode shows impressive electrochemical performances when evaluated as anode for NIB, delivering a reversible capacity of 400 mAh/g with capacity retention approaching 100% after 100 cycles. The excellent performances are attributed to defects induced by N-doping along with large surface area of hierarchical porous architecture that can facilitate the storage and diffusion of Na+ and prevent the restacking of rGO during cycling. Thus, these N-doped rGO fibrous materials have substantial promise for fabricating extended flexible cable electronics and NIBs with superior strength and performance.

The role of uniformly distributed ZnO nanoparticles on cellulose nanofibers in flexible solid state symmetric supercapacitors

Paper—a flexible, foldable, and cost-effective substrate made of one-dimensional cellulose nanofibers (1D-CNF)—is being extensively investigated as a promising aspirant for wearable as well as foldable energy storage appliances.

Hybrid Architecture of a Porous Polypyrrole Scaffold Loaded with Metal–Organic Frameworks for Flexible Solid-State Supercapacitors

Metal–organic frameworks (MOFs) are gaining more and more interest in the energy-storage technology. Especially, in supercapacitors, they are employed as electrode-active materials, owing to their ...

Self-Chargeable Flexible Solid-State Supercapacitors for Wearable Electronics.

Flexible supercapacitors (SCs) always face the charging issue when they are used in some special situations (e.g., wilderness island) that cannot provide electricity, which would limit the continuous energy supply for the attached wearable electronics. Herein, a self-chargeable flexible solid-state supercapacitor (FSSSC) was creatively constructed by sandwiching a piezoelectric polyvinyl alcohol/potassium hydroxide/barium titanate electrolyte between symmetric NiCo2O4@activated carbon cloth electrodes. By virtue of the efficient synergy of each component in the FSSSC, the device exhibits integrated merits with excellent flexibility, satisfactory electrochemical properties, and considerable self-charging capability through synchronously collecting and converting mechanical energy (e.g., repeated bending) into storable electrochemical energy in a persistent way. When the devices are serially connected and self-charged, they can be used to drive typical electronics with normal working. Such a unique material and device design enables the FSSSC with combined capabilities such as energy-harvesting and conversion and storage device for self-powered wearable electronics.

Fabrication of iron oxide-CNT based flexible asymmetric solid state supercapacitor device with high cyclic stability

Integration of high surface area nanostructures with conducting and deformable electrodes at large scale are of significant importance for flexible supercapacitors with high cyclic stability and low cost. Here, we report water assisted meter scale growth of aligned iron oxide and CNT 1D nanostructures on flexible stainless steel mesh for asymmetric supercapacitor device applications. Electron microscopic investigations revealed the uniform coverage of both iron oxide and CNT forest nanostructures over one meter length of SS mesh. Both iron oxide and CNT nanostructures were tested for supercapacitor electrode material in neutral electrolytes. Further, asymmetric solid state devices were fabricated and connected in serial fashion to demonstrate glowing of LEDs as well as rotation of 5 V micro fan. In addition, at bending angle of 90°, device showed 68% increase whereas, at 180° it showed 13% decrease in capacitance. The calculated specific capacitance for single device is found to be 14.4 mF cm−2. Corresponding energy density and power density are found to be 3 μW-hr cm−2 and 0.74 mW cm−2 respectively. The device showed remarkable capacitance retention of 87% over 25 000 charge discharge cycles. The flexible nature with remarkable cyclic stability of solid state iron oxide/CNT device is suitable for low cost flexible and wearable supercapacitor applications.

Carbon nanotube anodes decorated with Ag NWs/Ni(OH)2 NWs for efficient semitransparent flexible solid state supercapacitors

This work reports the electrochemical properties of flexible supercapacitors whose anodes were fabricated with carbon nanotubes (CNTs), silver nanowires (Ag NWs), and Nickel hydroxide nanowires (Ni(OH)2 NWs). The SEM analysis of the anodes demonstrated that the CNTs are oriented in a preferential direction, which favors the transport of charge carriers. Also, the Ag NWs, and Ni(OH)2 NWs have formed on the anodes a porous nanostructured network which look like a bird-nest, thus providing a high surface area for the charge storage. According to the optical transmittance spectra, the anodes made with the three components: CNTs, Ag NWs and Ni(OH)2 NWs presented an average transmittance of 46% in the visible region. The SC devices with anodes made with single CNT, CNT/Ag NWs, CNT/Ni(OH)2 NWs, and CNT/Ag NWs/Ni(OH)2 NWs were named CN, CN–Ag, CN–Ni, and CN–Ag/Ni, respectively. All these devices were semi-transparent and their cyclic voltammetry curves showed the presence of redox peaks, which suggest that these devices stored charge by redox reactions. In addition, the galvanostatic charge/discharge profiles of the SCs demonstrate that they can release energy for at least 10 h. The best SC device (CN–Ag/Ni) had a capacitance and energy density values of 88.6 F/g and 177.3 Wh/Kg, respectively. XPS, FTIR, and absorbance measurements were also carried out and confirmed the presence of oxygen vacancy defects, nickel hydroxides, silver oxides, and metallic silver in the anodes of the SCs. The presence of all these compounds was important because they acted as redox centers which all contribute simultaneously to the charge storage. Hence, the results presented here reveal that a flexible SC could be a feasible option as an energy source for portable devices.

A flexible composite electrolyte membrane with ultrahigh LLZTO garnet content for quasi solid state Li-air batteries

As an alternative next-generation energy storage device, solid state Li-air battery is generally investigated due to its high energy density and safety, yet the suitable solid state electrolyte and big overpotential issues hinder its application. Herein, we develop a novel flexible composite solid state electrolyte membrane with an ultrahigh LLZTO garnet content of ~89.6 wt% (LLZTO CMs) via a facile tap casting/phase-inversion process and a simple solution infiltration method. After introducing [Li∈12-C-4][I] supramolecular filler, LLZTO CMs exhibits high ionic conductivity of 6.92 × 10−4 S cm−1 at 20 °C and 2.85 × 10−3 S cm−1 at 80 °C, outstanding compatibility with Li metal and acceptable capability against Li dendrites. When pouch quasi solid state Li-air batteries are assembled with commercial carbon cloth (without any electrocatalysts) as oxygen electrode, a lower discharge-charge voltage gap of ~600 mV and an inspired cycling stability are obtained. This study suggests that LLZTO CMs could open a new avenue for developing advanced solid state Li-air batteries.

Chemical bath synthesis of NiCo2O4 nanoflowers with nanorods like thin film for flexible supercapacitor application-effect of urea concentration on structural conversion

In a simple chemical bath deposition, the flexible NiCo2O4 thin films with different nanostructures such as nanoflakes, nanoflowers with the surface composed of nanorods have been synthesized on stainless steel by changing the urea concentration of precursor. This study showed that the concentration of urea has a crucial role in the structural conversion of nanostructures. Here, the NiCo2O4 nanoflowers with nanorods like thin film demonstrated superior supercapacitive performance exhibiting a maximum specific capacitance of 702 F g−1 ascribed to the higher electronic conductivity of NiCo2O4 and lower ionic diffusion resistance due to nanoflowers with nanorods like mixed morphology. In further, the higher concentration of urea during synthesis leads to disorientation and overgrowth of the NiCo2O4 nanoflowers which deteriorated its supercapacitive performance. The two flexible solid state symmetric supercapacitor devices have been successfully fabricated using polyvinyl alcohol–KOH and polyvinyl alcohol-LiClO4 gel electrolytes. In comparison, the device with polyvinyl alcohol-LiClO4 gel exhibited superior performance exhibiting a maximum specific capacitance of 132 F g−1 with an energy density of 18.52 Wh kg−1 and a power density of 3.13 kW kg−1.

A Novel Quaternary Composite Solid State Electrolyte for Li Batteries

All-solid-state batteries continue to grow as an alternative to replace the traditional liquid-based ones not only because they provide increased safety but also higher power and energy density [1]. However, current solid-state electrolytes are either brittle (ceramics) or suffer low ionic conductivity at room temperature (polymers) [1]. Therefore, composite solid electrolytes are considered as a viable option. We have developed flexible and easy film-forming composite solid state electrolytes (CSEs). Our promising CSE is a quaternary composite that consists of the Solid polymer electrolyte (SPE) Poly(ethylene oxide)/ Lithium bis(trifluoromethanesulfonyl)imide (PEO/ LiTFSI), the fast conducting perovskite inorganic ceramic Li0.33La0.557TiO3 (LLTO) and the plasticizer Succinonitrile (SN). Over 40 samples with different (PEO/LiTFSI/LLTO/SN) compositions were prepared and characterized. The optimal mechanical and electrochemical properties was found for the sample 10S which has the following composition: 70%-PEO 12% LiTFSI 9%-LLTO 9%-SN. 10S had the ionic conductivity of ̴ 10-3 S/cm at 55 ̊ C and young’s modulus of around 105 MPa. The all-solid-state battery made by sandwiching 10S between a lithium metal anode and an NMC 532-based cathode achieved specific discharge capacities of 161 mAh/g at C/20. Pulsed-field gradient NMR was performed at different temperatures to measure the diffusion coefficient. The results have shown an Arrhenius-type dependence with a slope switch at around 55 ̊ C which is a similar behavior as the one observed in the Arrhenius plot obtained from conductivity measurements. Further investigation is underway to elucidate the conductivity mechanism in this new type of quaternary composite by advanced NMR and other techniquesReference[1] M. Keller, A. Varzi, S. Passerini, J. Power Sources 2018, 392, 206. Figure 1

Enhanced energy density of flexible asymmetric solid state supercapacitor device fabricated with amorphous thin film electrode materials

Supercapacitors have recently received immense interest in scientific community, as a complementary technology to batteries, to meet the various requirements for energy usage in practice. Amorphous MnO2 and CuS thin films are prepared on stainless steel-304 (SS) substrate by chemical bath deposition (CBD) and successive ionic layer adsorption and reaction (SILAR) methods, respectively. Asymmetric flexible solid state supercapacitor fabricated with configuration of SS/A-MnO2/Polyvinyl acetate (PVA)-Na2SO4/A-CuS/SS delivered an impressive specific energy of 57.4 Wh kg−1 at specific power 317 W kg−1 and excellent cycling stability over 10,000 cycles with capacitive retention of 84%. Moreover, series configuration of two asymmetric devices shows the capability of powering 211 red LEDs for ~150 s after charging for 30 s.

Flexible Transparent Symmetric Solid-State Supercapacitors Based on NiO-Decorated Nanofiber-Based Composite Electrodes with Excellent Mechanical Flexibility and Cyclability

We have prepared the flexible and transparent symmetric solid-state supercapacitors based on the nanofiber-based composite (NFC) electrodes decorated with NiO nanoparticles which exhibit better ele...

Enhanced Surface Area, Graphene Quantum Dots, and Functional Groups for the Simple Acid-Treated Carbon Fiber Electrode of Flexible Fiber-Type Solid-State Supercapacitors without Active Materials

Flexible fiber-type solid-state supercapacitors (FSCs) are demanded for energy storage of wearable soft electronics. A flexible carbon fiber (CF) with high electrical conductivity and good energy s...

Binder free lanthanum doped manganese oxide @ graphene oxide composite as high energy density electrode material for flexible symmetric solid state supercapacitor

The present work is about synthesis of La doped (1–5 vol %) manganese oxide (MnO2) @ graphene oxide (GO) composite electrode. The thin films are obtained using a facile and binder free successive ionic layer adsorption and reaction (SILAR) method. The scanning electron microscopic image of 3%La–MnO2@GO composite thin film shows porous spongy-like nanoparticles. Nitrogen desorption analysis shows that mesoporous sheets of 3%La–MnO2@GO exhibits large surface area up to 149 m2 g−1. The highest electrochemical specific capacitance of 729 F g−1 at the scan rate of 5 mV s−1 is obtained for 3%La–MnO2@GO electrode. The 3%La–MnO2@GO thin film electrode exhibits 94% capacitive retention over 5000 CV cycles. The flexible symmetric solid state supercapacitor device of configuration SS/3%La–MnO2@GO/PVA-Na2SO4/3%La–MnO2@GO/SS operating in potential window 1.8 V shows maximum specific capacitance of 140 F g−1 with energy density of 64 Wh kg−1 at power density of 1 kW kg−1 and capacitive retention of 90% after 5000 CV cycles at the scan rate of 100 mVs−1.