1,721,067 research outputs found
Electro-chemo-mechanics of solid state batteries: inelastic response to lithium plating and stripping
No full textOne of the most important issues facing modern science is how to deal with the rising need for storage technologies and renewable energy sources. There is likely no cutting-edge technology that can replace lithium-ion batteries (LiBs) for such purposes. Although the high ionic conductivity allows liquid organic electrolytes (LoEs) to remain state-of-the-art for this type of technology, the safety concerns correlated with these devices induce scientists to study new types of batteries with different kinds of electrolytes. Solid-state electrolytes (SSEs) are considered promising candidates to replace LoEs, due to their higher energy density, non-flammability, mechanical properties and electrochemical stability against lithium metal. However, a few drawbacks, like high contact resistance, reduced ionic conductivity compared with a liquid electrolyte, dendritic growth and degradation at the Li-foil anode, affect contemporary SSEs. A correct mechanical characterization of SSEs becomes paramount. The current work investigates the mechanical response of an all-solid-state lithium battery (ASSB). An electro-chemo-transport-mechanics model, in the realm of continuum mechanics and thermodynamics, is here proposed to describe the behaviour of a battery cell, in which the negative electrode consists of a lithium metal foil. Lithium deposition on the anode surface, accompanied by the shrinkage and expansion of the cathode, has been considered to evaluate the outbreak of mechanical stresses. A detailed investigation of the mechanical problem of growth connected with the inelastic nature of lithium has been carried out. The problem has been originally framed using an elasto-plastic constitutive model for lithium foil, which has been later enhanced to highlight its rate-dependent nature. The electrochemical response of the cell is investigated in terms of electric potential and species concentrations to complete the model description. To substantiate the reliability of the proposed model, it was tested against experimental galvanostatic discharge curves on a commercial all-solid-state thin film battery (Raijmakers et al. 2020 Electrochim. Acta330, 135147 (doi:10.1016/j.electacta.2019.135147)) and from a mechanical perspective, against the experimental outcomes of a tensile test performed on a lithium sample. Predictive science could provide new tools to reveal the physical laws behind the pitfalls that penalize the smooth operation and the performance of the ASSBs
Uncertainty Sources in Aerosol Jet Printed and Flexible Electrochemical Sensors
No full textElectrochemical sensors are nowadays used in a wide set of applications even though they still present major issues that weaken their metrological characteristics. Among those, noise is interesting because determines the lowest detectable concentration and allows developing better models for electrochemical sensors. In this work, a set of flexible electrochemical sensors produced by Aerosol Jet Printing (AJP) are analyzed to identify their different noise and uncertainty sources. Different conditions such as analyte concentration variations and temperature fluctuations are taken into consideration. Effects on noise of processes inherently connected with the transduction principle such as double-layer capacitance and mass transport were observed as well as a correlation between the analyte concentration and the overall noise. Thermal effects analysis revealed an overall increment of the noise level up to 52.4% in a 10°C interval while a variation of over 100% of the mean output current on the same interval are recorded. According to the results presented in this work, noise and temperature effects should be taken into consideration in the design of novel electrochemical devices to improve their reliability in uncontrolled conditions
Electro-chemo-mechanics of solid state batteries with lithium plating and stripping
Full text linkThis note is about a novel, thermodynamically consistent formulation for small strains continuum electro-chemo-mechanics applied to all solid state batteries, which are claimed to be the next-generation battery system in view of their safety accompanied by high energy densities. The response of a cell, made of a lithium metal foil, a solid electrolyte, and a porous LiCoO2 cathode, has been investigated in terms of quantities of interest such as the electric potential, the lithium concentrations profiles, displacements, and stresses. The plating and stripping of the lithium has been considered together with the volumetric evolution of the porous cathode. Together they contribute to the outbreak of mechanical stresses, which may influence the life cycle of a battery
Printed Strain Gauge on 3D and Low-Melting Point Plastic Surface by Aerosol Jet Printing and Photonic Curing
Full text linkPrinting sensors and electronics directly on the objects is very attractive for producing smart devices, but it is still a challenge. Indeed, in some applications, the substrate that supports the printed electronics could be non-planar or the thermal curing of the functional inks could damage temperature-sensitive substrates such as plastics, fabric or paper. In this paper, we propose a new method for manufacturing silver-based strain sensors with arbitrary and custom geometries directly on plastic objects with curvilinear surfaces: (1) the silver lines are deposited by aerosol jet printing, which can print on non-planar or 3D surfaces; (2) photonic sintering quickly cures the deposited layer, avoiding the overheating of the substrate. To validate the manufacturing process, we printed strain gauges with conventional geometry on polyvinyl chloride (PVC) conduits. The entire manufacturing process, included sensor wiring and optional encapsulation, is performed at room temperature, compatible with the plastic surface. At the end of the process, the measured thickness of the printed sensor was 8.72 μm on average, the volume resistivity was evaluated 40 μΩ∙cm, and the thermal coefficient resistance was measured 0.150 %/°C. The average resistance was (71 ± 7) Ω and the gauge factor was found to be 2.42 on average
Characterization Method for Bending Sensor Applied for Smart Glove
No full textNowadays accurate measurements of hand movements of workers in sectors such as manufacturing, aerospace, and healthcare are requested for different purposes, such as health analysis or human-robot interactions. In Industry 4.0, analyzing how workers interact with tools, machinery, and processes by hand it is important to achieve optimal performance, quality control, safety, and ergonomics. Several techniques - motion capture and wearable sensors - are available with different levels of accuracy and applicability. In particular, smart gloves, and in specific bend sensors, represent a viable solution to measure comfort level, but commercial solutions lack accuracy and affordability. For this reason, new sensors applied to wearable devices and therefore suitable characterization methods are needed. In this paper, a novel platform that emulates the finger movements is proposed to evaluate the sensors used to measure the rotation of two or more finger joints. For example, one bend sensor is used to measure more than one finger joint. The platform integrates a dummy little and index finger of average dimensions. With respect to previous works, the proposed method was used to test commercial bend sensors bent in two points, corresponding to two finger joints. The experimental results confirmed the sensor characteristics, especially regarding the linearity (the maximum error is less than 2.5%) and the repeatability (the maximum error is less than 3.8%). Finally, a relationship between the resistance and the curvature was found when the sensor was bent in two points, obtaining the same characteristics in terms of linearity and repeatability
Mobile Autonomous System for Measuring Pollutants in Indoor Environments
No full textThe panorama of air quality monitoring is constantly evolving, and its importance has become increasingly fundamental even in indoor environments. Recent studies show the impact of indoor air pollutants on human health. Since individuals spend a substantial part of their lives indoors, more and more attention is paid to guaranteeing the safety and purity of indoor air to safeguard health both at home and in the workplace. In this work, the design and development of an autonomous mobile measurement system dedicated to the sampling and analysis of indoor air quality in closed environments is presented. The system consists of a rover and several sensor technologies to provide a comprehensive assessment of air quality. The system moves autonomously in the closed environment, monitoring pollutants and transmitting data via wi-fi connection to the cloud for analysis and identification of possible dangerous situations. The preliminary tests carried out include the evaluation of various pollution scenarios, such as the presence of smoke, exhaust gases, chemical pollutants, and gas leaks. Furthermore, the autonomous mobile measurement system has been validated during about 12 hours in a real indoor environment. The presented work also offers a critical analysis and interpretation of these results, illustrating the practical implications and effectiveness of the proposed system in real contexts
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