Fabrication Of Flexible Micro-supercapacitors Research Articles

Stamp-assisted flexible graphene-based micro-supercapacitors

The rapid growth of portable and wearable electronics have greatly stimulated simplified fabrication of energy storage devices, from which micro-supercapacitors (MSCs) are an ideal power source, due to high power density and long lifetime. However, the development of a simple and cost-effective procedure towards the fabrication of high-performance MSCs is still a challenge. To this end, here we report a self-patterned stamping process through pre-designed patterns (Fractal & Interdigital) on parafilm® coated polyethylene terephthalate (PET) substrate for the fabrication of a flexible and planar MSC. The imprinted patterns on parafilm® are filled by graphene oxide (GO)/carbon aerogel/MnO2 hybrid paste as a binder and additive-free active material, followed by GO reduction through a safe, low cost, and effective procedure using nascent hydrogen. In contrast to the hydrazine based reduction method, nascent hydrogen affords the integrity and stability to the active material without any peeling off from the substrate, with low ohmic resistance. The prepared MSCs display large capacitance and energy density of 8.7 mF cm−2 (43.66 F cm−3) and 6 mWh cm−3 for Interdigital electrode and 14.2 mF cm−2 (71.34 F cm−3) and 9.9 mWh cm−3 for Fractal electrode, respectively. Furthermore, the MSC displays capacitance retention of 85% after 25,000 cycles. The presented procedure is a simple and cost-effective strategy towards the fabrication of flexible MSCs with state-of-the-art performance.

Materials Technology for Renewable Energies

Global warming and climate change are major challenges facing our society in the 21st century. They are mainly caused by the burning of fossil fuels for energy. The adoption of renewable energies will play a pivotal role in reducing greenhouse gas emissions. Materials technologies are critical for the production, harvesting, storage and transmission of renewable energies to realize sustainable development. This special issue published in collaboration with Advanced Sustainable Systems, presents research outcomes, reviews and discussions on topics related to renewable energy technologies: i) hydrogen storage and antiferroelectrics for energy storage, ii) single nanowire solar cells, iii) advanced lithium-ion batteries and flexible lithium-ion batteries and microsupercapacitors, iv) carbon dioxide reduction, and v) low-cost sodium-based batteries and high-energy lithium-sulfur batteries. Hydrogen is a zero-emission fuel. However, its usage has been restricted by the lack of a suitable storage technology. The review in this issue summarizes nanosized light element hydrides to enable hydrogen storage at ambient conditions. Dielectric capacitors are capable of delivering both high energy densities and power densities. Strategies are discussed for improving the performance of antiferroelectric ceramic based capacitors. Furthermore, nanowire solar cells based on different III-V semiconductor nanowire materials are analysed for fabricating high-efficiency solar cells. Carbon dioxide reduction can produce valuable products. Various catalyst materials are reviewed to reveal their intrinsic microstructure and electronic properties towards electrochemical reduction of carbon dioxide. Lithium-ion batteries are currently dominating power sources for portable electronics and electric vehicles, and also are widely applied for the storage of electricity generated by renewable sources such as solar and wind. In this issue, we revisit the development of high-performance lithium-ion batteries. Plasma enabled synthesis and processing of materials are explored for lithium-ion batteries, including electrode materials, separators and electrolytes. Meanwhile, recent advances in flexible lithium-ion batteries are presented with a focus on flexible electrodes, electrolyte and cell structure. In addition, progress on the fabrication of flexible micro-supercapacitors is also discussed for wearable electronic devices. Low-cost rechargeable batteries are in high demand for large-scale energy storage. The abundance of sodium in nature is driving a renaissance of sodium-ion batteries. Titanium oxides as negative materials for sodium-ion batteries are comprehensively reviewed in this issue with emphasis on sodium storage mechanisms and strategies to improve the cycling stability, Coulombic efficiency and kinetic behaviour. Room-temperature sodium-oxygen batteries not only can maintain low cost, but also can deliver high energy density. In this regard, recent achievements and remaining challenges for rechargeable sodium-oxygen batteries are summarized with detailed discussions on the reaction mechanism, cathode materials, sodium anodes, electrolytes and other key components. Finally, the progress of lithium-sulfur batteries is deliberated to understand the complex sulfur redox chemistry and aims to lay foundations for mechanistic investigations on lithium-sulfur batteries. More articles on renewable energy technologies can be found in the Special Issue published in the sister journal Advanced Sustainable Systems. It has been an absolute joy and pleasure to edit this special issue. I would like to thank the Editor-in-Chief of Advanced Materials Technologies – Dr. Esther Levy, for coordinating the special issue and handling all papers. I would like to sincerely thank all authors for their high-quality contributions to this special issue. Professor Guoxiu Wang is the Director of the Centre for Clean Energy Technology and a Distinguished Professor at University of Technology Sydney (UTS), Australia. He is an expert in materials chemistry, electrochemistry, energy storage and conversion, and battery technologies. He is a member of the Australian Research Council (ARC) College of Experts. His research interests include lithium-ion batteries, lithium-air batteries, sodium-ion batteries, lithium-sulfur batteries, supercapacitors, hydrogen storage materials, fuel cells, graphene and MXenes.