Flexible supercapacitors (FSC) are revolutionizing smart wearable and implantable electronic devices, offering excellent mechanical flexibility and outstanding energy and power densities. In this work, we report a new sustainable paper-based FSC which consists of a paper substrate loaded with graphite ink, carbon black, and gold nanoparticles sandwiched with a solid-state electrolyte. The materials are deposited on a paper-based substrate, thus establishing a novel approach to eco-friendly, high-performance FSC. The prepared materials and FSCs were morphologically and electrochemically characterized by scanning electron microscopy, electrochemical impedance spectroscopy, cyclic voltammetry, and galvanostatic charge-discharge tests. When the weight ratio of graphite ink/carbon black/gold nanoparticles is adjusted to 93 wt%/5 wt%/2 wt%, respectively, the resulting FSC exhibits the optimal electrochemical performances demonstrated by: (i) specific capacitance of 154 mF/cm2, (ii) energy density of 0.013 mWh/cm2, (iii) power density of 6.5 mW/cm2, and (iv) extended cycling stability of 85% after 10 000 cycles. This work highlights the significant role of standard office paper for the suitable contribution to develop flexible and sustainable electrochemical energy storage devices in advancing the functionality and autonomy of current and future portable and wearable electronics systems, paving the way for large-scale production of cost-effective and flexible printed devices.

The important growing demand for flexible and wearable smart electronic devices has driven the urgent need for cost-effective, safe and flexible energy storage devices. In response to this challenge, we propose the development of a flexible supercapacitor based on carbon xerogel (CX) as the negative electrode and manganese dioxide (MnO2) as the positive electrode, both printed onto a carbon cloth substrate. Comprehensive structural and electrochemical characterisations were performed using a combination of Raman, ATR-FTIR and X-ray photoelectron spectroscopy (XPS) to elucidate the relationship between the chemical structure and performance. Combined spectroscopic analysis reveals that the MnO2 is predominantly amorphous with short-range alpha-MnO2like ordering and a mixed of Mn4+/Mn3+ sites associated with Mn structural defects and oxygen vacancies. These mixed-valence centres promote fast, reversible surface redox reactions, thereby enhancing pseudocapacitive charge storage while preserving structural stability during cycling. The resulting device demonstrates superior performance, with a high specific capacitance of 580 mF & sdot;cm- 2 and an energy density of 261 mu Wh & sdot;cm- 2 at a power density of 2 mW & sdot;cm- 2. However, lower performances were observed when the flexible electrodes were assembled into free-standing devices. Furthermore, the fabricated devices were subjected to various mechanical and flexibility tests while powering a ring-shaped LED module containing 30 LEDs integrated into a lab-coat textile. The two devices in series maintained stable illumination for 50 s with no performance degradation, demonstrating their excellent mechanical strength and potential for integration into wearable textiles.

Up to now, the scientific community has achieved a significant progress in designing innovative, flexible and conductive materials, paving the way for the advancement of cutting-edge electronic devices dedicated for smart wearable applications. Herein, the introduction of carbon cloth (CC)-based platform for energy storage devices was adopted for nanomaterial coating and improved multilayer adhesion. Using carbon xerogel (CX) and manganese dioxide (MnO2) printed on CC, an asymmetric supercapacitor was developed, achieving a high specific capacitance of 213 F g- 1, energy density of 24 Wh & sdot;kg- 1, at a power density of 180 W kg- 1, and low selfdischarge rate with a voltage retention of 72 % after 22 h. This work paves the way for the adoption of carbon cloth thanks to its outstanding features as a promising and flexible platform to drive the development of nextgeneration smart and wearable electronic devices dedicated for healthcare and environmental monitoring applications.

The monitoring of oxygen in food packaging during storage and transportation is crucial in food quality surveillance, warning users regarding food spoiling, happening through compound oxidation and aerobic microorganism proliferation. In this overall scenario, we report the development of a flexible, cost-effective, and Bluetooth-assisted electrochemical sensor for oxygen detection in food packaging. The device encompasses three layers, namely a zinc sheet as an anode, a conductive silver ink printed on an oriented polypropylene sheet serving as a cathode, and a deep eutectic solvent deposited on a paper-based substrate sandwiched between both electrodes. The sensing tool provided a wide linear range for oxygen detection up to 20.9 O2% v/v with good intra-electrode repeatability (RSD % = 0.02 %). Finally, the developed device was integrated with a 3D printed holder and tested for oxygen detection in packages containing mushrooms, tomatoes, and broccoli samples, obtaining a good correlation with the reference method. This study opens noticeable possibilities for employing paper-based metal-air batteries in the detection of specific target analytes, by integrating paper substrate and metal-based batteries delivering smart and self-powered instruments as reliable and accurate analytical tools.

Portable and easy-to-use analytical devices for biomedical and environmental monitoring are prone to changing the paradigm of sensor applications in daily life. Besides the several sensing principles used to address almost every analytical purpose, one of the main challenges entails making that technology easy to use by end-users to fill in the gap between sensor development and real application. Smartphones, being the most widely used mobile devices in the current society, match very well with this need. Indeed, smartphones offer the possibility to combine the most cutting-edge technology in electronic software (e.g., easiness of app development) and wireless data sharing (e.g., through the internet cloud) with sensor technology, to give birth to hand-held analytical tools that can carry out the entire sensing process, from the analysis to the management of the results. Such an integrated tools are expected to kick off a new era for healthcare/environment monitoring due to a superior balancing among sustainability, cost-effectiveness, real-time analysis, data sharing, and portability. The present book chapter displays a general overview of the most recent progress achieved in integrating electrochemical (bio)sensors with smartphone technology, aiming to inspire researchers towards conceiving novel all-in-one sensing approaches. Such affordable, reliable, modern, and eco-friendly devices perfectly meet the principles of Green and White Analytical Chemistry as well as address the requirements claimed by the United Nations in the Sustainable Development Agenda 2030, being able to boost effective interventions for water cleaning/sanitation and for good health/well-being by means of sustainable analytical solutions.

The present chapter deals with strategies for optimizing the development of smart flexible electronics presented a new type of device having a great potential for versatile applications. The widespread commercialization of flexible electronics is limited by the lack of incorporation of energy storage since conventional devices such as supercapacitors are bulky and heavy. Therefore, it is compulsory to develop new energy storage integrated on flexible substrates and used for example in the smart textile industry. The introduction of flexible devices with excellent electrochemical performances become a great challenge to provide the requirements for daily applications. Carbonaceous-based nanomaterials show versatile advantages. Therefore, they have been considered useful in different applications, especially as energy storage devices. This concept gives rise to an inspiration for comprehensive utilization of Carbonaceous-based nanomaterials with a green, and low-cost process to contribute to an affordable, reliable, and modern eco-friendly energy storage devices.

This work presents a state of the art review of energy storage systems and its applications integrating an alternative technology for the electrical energy generation known as supercapacitors and batteries. Indeed, this review focuses on supercapacitors and batteries as energy storage systems. The state of the art review contains an analysis of the evolution of electroactive materials and a classical modeling based on electric equivalent circuits. The synthesis of electrical circuits from physics-based batteries and supercapacitor models that represent con-servation and diffusion interactions is the subject of this research. To create the circuits, the suggested synthesis technique employs model discretization, linearization, balanced model order reduction, and passive network synthesis. Physical models are used to create circuits with various topologies. There is no such complex inves-tigation to the best of our knowledge, has not been reported and is expected to lead to breakthrough de-velopments to obtain nanocomposites.

In today's nanoscale regime, new electronics technology such as smartphones, sensors, and personal healthcare devices has been increased and thus requires emerging developments in terms of flexible and sustainable energy storage devices as power sources. Indeed, the power and the energy densities should be safe, reliable, low-cost, and eco-friendly within the highly integrated systems in the human body. Therefore, the use of biomass wastes to ensure the ecological and cost-effective aspect presents an alternative strategy in the field of electrochemical energy storage. In this context, activated carbon derived from coffee wastes, was used as an active material for the elaboration of high performances textile-based Electric Double Layer Capacitors (EDLC). A quasi-solid-state electrolyte has been integrated to guarantee the flexibility and light weight criteria, as well as high operating potential (2V) which allows reaching high energy densities. The textile-based device was characterized and modeled using equivalent electrical circuits. The as prepared supercapacitor exhibits a specific capacitance of 80 mF/g, an energy and power densities of 5.36 mWh/Kg and 4.87 W/Kg respectively. This process followed the choice of cost-effective materials such as activated carbon from biomass precursor and polyvinyl alcohol would make it particularly viable for such daily and industrial applications in large-scale production to store clean, reliable, and modern energies at an affordable cost.

Supercapacitors and batteries are among the most promising electrochemical energy storage technologies available today. Indeed, high demands in energy storage devices require cost-effective fabrication and robust electroactive materials. In this review, we summarized recent progress and challenges made in the development of mostly nanostructured materials as well as fabrication routes for energy storage devices. Indeed, we systematically sorted out the design principles of electrode materials such as lithium-ion, lead-acid, lithium-sulfur, nickel-cadmium, nickel-metal hydride, and sodium-ion for rechargeable batteries electrode and supercapacitors (SCs) electrode materials following by systematic discussions on electric double-layer capacitors, pseudocapacitors, and hybrid SCs behavior.

The introduction of paper-based platforms for developing novel energy storage devices such as supercapacitors (SCs) highlights new promising opportunities in the field of flexible electronics. Herein, the use of paper-based substrate has shown reduced manufacturing cost and simplified coating process by screen-printing technology, as well as an improvement of the multilayer structure adhesion. The SC manufactured with Graphite ink mixed with Carbon Black (CB)/Prussian blue (PB) at different weight ratios (0, 3, 4, 5, 7, and 10 wt %) shows good performances. An optimum weight ratio of carbon black/prussian blue. 4 wt % is consistent with the following features: i) specific capacitance of 253 mF/cm(2) at 0.01 V/s, ii) specific energy density of 0.5 mWh/cm(2), iii) specific power density of 0.1 mW/cm(2), and iv) good cycling stability (94%) after 5000 cycles. The proposed fabrication approach exhibits a simple scale-up, a low environmental impact and a decrease of manufacturing costs: it provides self-supporting electrodes based on a mixture of graphite ink and CB/PB nanocomposite.

Polyvinyl alcohol (PVA)/multi-walled carbon nanotubes (MWCNT) nanocomposites based films were synthesized by a facile pathway (solution casting method) with different weight ratios of MWCNT (0 wt%, 1 wt%, 3 wt %, 4 wt% and 5 wt%). FTIR measurements confirmed the interaction between MWCNT and PVA molecular chains. From UV Visible spectroscopy study, the band gaps of PVA/MWCNT nanocomposites were calculated and we have observed a linear decrease with MWCNT addition. Photoluminescence (PL) spectroscopy study showed that the PVA emission is dominated by a broad band around 400 nm and decreases with MWCNTs content. The analysis of I-V characteristics shows an important current increase with MWCNT addition with a percolation threshold at about 4 wt%. Moreover, they have been simulated successfully with the established theory and have shown an ideality factor close to 1. These nanocomposites could be considered as promising candidates to be used in future nanotechnology based devices.