Batterie au plomb | EPFL Graph Search

Une batterie au plomb est un accumulateur électrochimique dont les électrodes sont à base de plomb et l'électrolyte est un mélange d'eau et d'acide sulfurique. Cette batterie est généralement constituée de plusieurs cellules en série, afin d'obtenir la tension désirée, et réunies dans un même boîtier. Les électrodes sont des plaques ou grilles constituées d'un alliage de plomb dit "durci" (par exemple à l'aide d'étain, de cadmium et de strontium, à raison de quelques pour cent de l'alliage). Ce système de « stockage » d'électricité est largement utilisé dans l'industrie, dans l'équipement des véhicules ferroviaires et automobiles (camions compris) mais aussi à chaque fois que l'on a besoin d'une énergie électrique immédiatement disponible (avion, satellite). Historique vignette|Vue en coupe d'une batterie de voiture avec ses 6 cellules reliées en série et ses plaques de plomb L'accumulateur au plomb a été inventé en 1854 par Wilhelm Josef Sinsteden. En 1859, le Français G

Thermodynamics of organic electrochemical transistors

Hsin Tseng

Though models describing the operating mechanism of organic electrochemical transistors (OECTs) have been developed, these models are unable to accurately reproduce OECT electrical characteristics. Here, the authors report a thermodynamic-based framework that accurately models OECT operation. Despite their increasing usefulness in a wide variety of applications, organic electrochemical transistors still lack a comprehensive and unifying physical framework able to describe the current-voltage characteristics and the polymer/electrolyte interactions simultaneously. Building upon thermodynamic axioms, we present a quantitative analysis of the operation of organic electrochemical transistors. We reveal that the entropy of mixing is the main driving force behind the redox mechanism that rules the transfer properties of such devices in electrolytic environments. In the light of these findings, we show that traditional models used for organic electrochemical transistors, based on the theory of field-effect transistors, fall short as they treat the active material as a simple capacitor while ignoring the material properties and energetic interactions. Finally, by analyzing a large spectrum of solvents and device regimes, we quantify the entropic and enthalpic contributions and put forward an approach for targeted material design and device applications.

NATURE PORTFOLIO2022

A review of sustainable energy access and technologies for healthcare facilities in the Global South

Andrea Franco, Silvia Hostettler, Dikolela Kalubi, Marjan Shaker

Access to reliable, affordable and sustainable energy is essential for improving living standards, development and economic growth. From a healthcare perspective, energy is a critical parameter for delivering and improving healthcare services and life-saving interventions in the Global South. This review provides an estimation of the energy needs of different healthcare facilities as a function of patient capacity and services provided. It also presents the strengths and limitations of several energy sources that can be used to meet these needs. The review focuses on energy provision in off-grid scenarios and for satisfying peak demands of grid-connected hospitals. The initial key observations are that fossil-fuel generators are the main energy source because of their low investment costs. However, this technology can no longer compete with the energy produced from renewable sources in terms of levelized cost of electricity (LCOE). Photovoltaics (PV) has an LCOE of 0.09 USD/kWh, versus an average 0.25 USD/kWh for diesel generators. Moreover, PV is a modular technology that can efficiently meet energy demands in an environment-friendly way. Wind turbines share many strengths of PV and yet both technologies suffer from intermittent energy sources. They must therefore be coupled with a storage system that provides continuous and stable electricity. Today, energy is mainly stored electrochemically, in the form of lead-acid batteries. However, this review shows that nickel-metal hydride (NiMH) should be used when possible for their higher energy density (200 Wh/l versus 80 Wh/l), non-toxicity, safety and simple maintenance. Alternatively, lithium-based batteries should be used when the energy density and number of cycles is a priority. Other energy production means (e.g., hydropower) and storage technologies (e.g., flywheels) are reviewed as well. In conclusion, the optimal energy solution for medium-to-large healthcare facilities, especially for those in off-grid settings, is a hybrid system wherein the strengths of a renewable energy source coupled with efficient batteries is combined with a diesel generator to minimize the LCOE.

Elsevier Science Bv2017

Synergic Effect of Dendrite-Free and Zinc Gating in Lignin-Containing Cellulose Nanofibers-MXene Layer Enabling Long-Cycle-Life Zinc Metal Batteries

Zhen Li, Yao Wang, Xu Zhang, Kangning Zhao

Uncontrollable zinc dendrite growth and parasitic reactions have greatly hindered the development of high energy and long life rechargeable aqueous zinc-ion batteries. Herein, the synergic effect of a bifunctional lignin-containing cellulose nanofiber (LCNF)-MXene (LM) layer to stabilize the interface of zinc anode is reported. On one hand, the LCNF provides enough strength (43.7 MPa) at relative low porosity (52.2%) to enable the diffusion limited dendrite suppression, while, on the other hand, the MXene serves as a zinc gating layer, facilitating the zinc ion mobility, restricting the active water/anions from degradation in the electrode/electrolyte interface, and epitaxially guiding zinc deposition along (002) plane. Benefiting from the synergic effect of diffusion limited dendrite suppression and zinc gate, the LM layer enabled a high coulombic efficiency (CE) of 98.9% with a low overpotential of 43.1 mV at 1 mA cm(-2) in Zn//Cu asymmetric cells. More importantly, Zn//MnO2 full cells with the LM layer achieve a high-capacity retention of 90.0% for over 1000 cycles at 1 A g(-1), much higher than the full cell without the protective layer (73.9% over 500 cycles). The work provides a new insight in designing a dendrite-free zinc anode for long-cycle-life batteries.

WILEY2022

A review of sustainable energy access and technologies for healthcare facilities in the Global South

Andrea Franco, Silvia Hostettler, Dikolela Kalubi, Marjan Shaker

Elsevier Science Bv2017