Self-Standing Metallic Mesh with MnO2 Multiscale Microstructures for High-Capacity Flexible Transparent Energy Storage

Fabrication of Coral-like Polyaniline/Continuously Reinforced Carbon Nanotube Woven Composite Films for Flexible High-Stability Supercapacitor Electrodes

The electrochemical performance is significantly influenced by the structure and surface morphology of the electrode materials used in supercapacitors. Using the floating catalytic chemical vapor deposition (FCCVD) technique, a self-supporting, flexible layer of continuously reinforced carbon nanotube woven film (CNWF) was developed. Then, polyaniline (PANI) was formed in the conductive network of CNWF using cyclic voltammetry electrochemical polymerization (CVEP) in various aqueous electrolytes to produce a series of flexible CNWF/PANI composite films. The impacts of the CVEP period, electrolyte type, and electrolyte concentration on the surface morphology, doping degree, and hydrophilicity of CNWF/PANI composite films were thoroughly examined. The CNWF/PANI₁-15C composite electrode, which was created using 15 cycles of CVEP in a solution of 1 M sodium bisulfate, displayed a distinctive coral-like PANI layer with a well-defined sharp nanoprotuberance structure, a 48% doping degree, and a quick reversible pseudocapacitive storage mechanism. At a current density of 1 A g^-1, the energy density and specific capacitance reached 54.9 Wh kg^-1 and 1098.0 F g^-1, respectively, with a specific capacitance retention rate of 75.9% maintained at 10 A g^-1. Both the specific capacitance and coulomb efficiency were maintained at 96.9% and more than 98.1% of their initial values after being subjected to 2000 cycles of galvanostatic charge and discharge, demonstrating excellent electrochemical cycling stability. The CNWF/PANI₁-15C composite film, an ideal electrode material, offers a promising future in the field of flexible energy storage due to its exceptional mechanical properties (127.9 MPa tensile strength and 16.2% elongation at break).

Freestanding 3D Metallic Micromesh for High-Performance Flexible Transparent Solid-State Zinc Batteries

Flexible transparent energy supplies are extremely essential to the fast-growing flexible electronic systems. However, the general developed flexible transparent energy storage devices are severely limited by the challenges of low energy density, safety issues, and/or poor compatibility. In this work, a freestanding 3D hierarchical metallic micromesh with remarkble optoelectronic properties (T = 89.59% and R_s = 0.23 Ω sq^-1 ) and super-flexibility is designed and manufactured for flexible transparent alkaline zinc batteries. The 3D Ni micromesh supported Cu(OH)₂ @NiCo bimetallic hydroxide flexible transparent electrode (3D NM@Cu(OH)₂ @NiCo BH) is obtained by a combination of photolithography, chemical etching, and electrodeposition. The negative electrode is constructed by electrodeposition of electrochemically active zinc on the surface of Ni@Cu micromesh (Ni@Cu@Zn MM). The metallic micromesh with 3D hierarchical nanoarchitecture can not only ensure low sheet resistance, but also realize high mass loading of active materials and short electron/ion transmission path, which can guarantee high energy density and high-rate capability of the transparent devices. The flexible transparent 3D NM@Cu(OH)₂ @NiCo BH electrode realizes a specific capacity of 66.03 μAh cm^-2 at 1 mA cm^-2 with a transmittance of 63%. Furthermore, the assembled solid-state NiCo-Zn alkaline battery exhibits a desirable energy density/power density of 35.89 μWh cm^-2 /2000.26 μW cm^-2 with a transmittance of 54.34%.

Near infrared photothermoelectric effect in transparent AZO/ITO/Ag/ITO thin films

A new concept of oxide-metal-oxide structures that combine photothermoelectric effect with high reflectance (~ 80%) at wavelengths in the infrared (> 1100 nm) and high transmittance in the visible range is reported here. This was observed in optimized ITO/Ag/ITO structure, 20 nm of Silver (Ag) and 40 nm of Indium Tin Oxide (ITO), deposited on Aluminum doped Zinc Oxide (AZO) thin film. These layers show high energy saving efficiency by keeping the temperature constant inside a glazed compartment under solar radiation, but additionally they also show a photothermoelectric effect. Under uniform heating of the sample a thermoelectric effect is observed (S = 40 mV/K), but when irradiated, a potential proportional to the intensity of the radiation is also observed. Therefore, in addition to thermal control in windows, these low emission coatings can be applied as transparent photothermoelectric devices.

High-Performance Transparent and Conductive Films with Fully Enclosed Metal Mesh

Metal mesh films as a kind of transparent conductive electrodes (TCEs) have shown high promise in various optoelectronic devices but are still challenged by a combination of high conductivity and transparency, mechanical robustness, and uniform electric field. Herein, we demonstrate a new concept of transparent and conductive films with a fully enclosed metal mesh, which is embedded in deep microcavities and is coated with a conductive polymer layer to combine these metrics. To ensure high conductivity and transparency, metal ink is filled into the fine (down to submicrometers) and deep mesh microcavities by electrowetting-assisted blading with low square resistances of 0.4 and 2.69 Ω sq^-1 at typical transmittances of 76.9 and 87.4%, respectively. The covered thin conductive polymer layer improves the electric field uniformity of metal mesh films by at least three orders of magnitude. The fully enclosed metal mesh films exhibit excellent mechanical flexibility, indicated by the fact that the resistance is almost unchanged after 10,000 bending cycles at a bending radius of ∼5 mm. Based on the fully enclosed metal mesh films, the emission intensity of alternating current electroluminescent devices is improved by more than three times compared with that in the case of solely using common metal mesh films.

Solid Polymer Electrolytes with High Conductivity and Transference Number of Li Ions for Li-Based Rechargeable Batteries

Smart electronics and wearable devices require batteries with increased energy density, enhanced safety, and improved mechanical flexibility. However, current state-of-the-art Li-based rechargeable batteries (LBRBs) use highly reactive and flowable liquid electrolytes, severely limiting their ability to meet the above requirements. Therefore, solid polymer electrolytes (SPEs) are introduced to tackle the issues of liquid electrolytes. Nevertheless, due to their low Li⁺ conductivity and Li⁺ transference number (LITN) (around 10^-5 S cm^-1 and 0.5, respectively), SPE-based room temperature LBRBs are still in their early stages of development. This paper reviews the principles of Li⁺ conduction inside SPEs and the corresponding strategies to improve the Li⁺ conductivity and LITN of SPEs. Some representative applications of SPEs in high-energy density, safe, and flexible LBRBs are then introduced and prospected.

Constructed Ag NW@Bi/Al core-shell nano-architectures for high-performance flexible and transparent energy storage device

Flexible and transparent energy storage devices (FTESDs) have recently attracted much attention for use in wearable and portable electronics. Herein, we developed an Ag nanowire (NW) @Bi/Al nanostructure as a transparent negative electrode for FTESDs. In the core-shell nanoarchitecture, the Ag NW percolation network with excellent conductivity contributes superior electron transport pathways, while the unique nanostructure provides an effective interface contact between the current collector and electroactive material. As a result, the electrode delivers a high capacity of 12.36 mF cm-2 (3.43 μA h cm-2) at 0.2 mA cm-2. With a minor addition of Al, the coulombic efficiency of the electrode remarkably increases from 65.1% to 83.9% and the capacity retention rate improves from 53.8% to 91.9% after 2000 cycles. Moreover, a maximum energy density of 319.5 μW h cm-2 and a power density of 27.5 mW cm-2 were realized by an interdigital structured device with a transmittance of 58% and a potential window of 1.6 V. This work provides a new negative electrode material for high-performance FTESDs in the next-generation integrated electronics market.

Nanostructured manganese dioxide for anticancer applications: preparation, diagnosis, and therapy

Nanostructured manganese dioxide (MnO₂) has attracted extensive attention in the field of anticancer applications. As we all know, the tumor microenvironment is usually characterized by a high glutathione (GSH) concentration, overproduced hydrogen peroxide (H₂O₂), acidity, and hypoxia, which affect the efficacy of many traditional treatments such as chemotherapy, radiotherapy, and surgery. Fortunately, as one kind of redox-active nanomaterial, nanostructured MnO₂ has many excellent properties such as strong oxidation ability, excellent catalytic activity, and good biodegradability. It can be used effectively in diagnosis and treatment when it reacts with some harmful substances in the tumor site. It can not only enhance the therapeutic effect but also adjust the tumor microenvironment. Therefore, it is necessary to present the recent achievements and progression of nanostructured MnO₂ for anticancer applications, including preparation methods, diagnosis, and treatment. Special attention was paid to photodynamic therapy (PDT), bioimaging and cancer diagnosis (BCD), and drug delivery systems (DDS). This review is expected to provide helpful guidance on further research of nanostructured MnO₂ for anticancer applications.

Controlling Electrode Spacing by Polystyrene Microsphere Spacers for Highly Stable and Flexible Transparent Supercapacitors

Transparent polymer electrolytes such as poly(vinyl alcohol)-based H⁺, Li⁺, K⁺, and Na⁺ gels have been widely used as both an electrolyte and a separator for flexible transparent supercapacitors (FTSCs). However, these gels sandwiched between the electrodes in FTSCs are easily compressed under bending and compression due to their viscous flow behavior, resulting in the deformation of electrode spacing and the unstable capacitance performance. To resolve this issue, herein, we introduce monodispersed polystyrene (PS) microspheres into PVA-LiCl polymer gel electrolytes as spacers to precisely control the electrode spacing during the assembly of FTSCs using single-walled carbon nanotubes/indium tin oxide-polyethylene terephthalate (ITO-PET) or MnO₂/multiwalled carbon nanotubes/ITO-PET as transparent electrodes. The electrode spacing could be tuned by varying the diameter of PS microspheres, for example, 20, 40, and 80 μm. More importantly, the PS microsphere spacers protect the gel electrolyte from the squeeze when bending takes place, allowing the stable performance output by FTSCs under a bending state. After repeating bending tests, the capacitance remains 95.6%, indicating the high stability and flexibility of the devices with the assistance of PS microsphere spacers.