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Refractive Index Measurement of Lithium Ion Battery Electrolyte with Etched Surface Cladding Waveguide Bragg Gratings and Cell Electrode State Monitoring by Optical Strain Sensors
摘要： In this scientific publication, a new sensor approach for status monitoring, such as state of charge and state of health, of lithium ion batteries by using special Bragg gratings inscribed into standard optical glass fibers is presented. In addition to well-known core gratings, embedded into the anode of 5 Ah lithium ion pouch cells as a strain monitoring unit, the manufacturing of a surface cladding waveguide Bragg grating sensor incorporated into the cell’s separator, that is sensitive to changes of the refractive index of the surrounding medium, is demonstrated. On the basis of the experiments carried out, characteristics of the cell behavior during standard cyclization and recognizable marks in subsequent post-mortem analyses of the cell components are shown. No negative influence on the cell performance due to the integrated sensors have been observed; however, the results show a clear correlation between fading cell capacity and changes of the interior optical signals. Additionally, with the novel photonic sensor, variations in the electrolyte characteristics are determinable as the refractive index of the solution changes at different molar compositions. Furthermore, with the manufactured battery cells, abuse tests by overcharging were conducted, and it was thereby demonstrated how internal battery sensors can derive additional information beyond conventional battery management systems to feasibly prevent catastrophic cell failures. The result of the research work is an early stage photonic sensor that combines chemical, mechanical and thermal information from inside the cell for an enhanced battery status analysis.
关键词： lithium ion,battery aging,cladding waveguide,battery electrolyte,optical sensors,battery safety,fiber Bragg grating,electrode active material,status monitoring
更新于2025-11-28 14:23:57
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Optimization of a parallel-plate RF probe for high resolution thin film imaging
摘要： Choosing an MR probe with the correct dimensions and high sensitivity is critical for magnetic resonance imaging, especially high resolution thin film imaging. In this work, a parallel‐plate resonator has been optimized for strength and uniformity of the B1 magnetic field. The parallel‐plate resonator is designed for high resolution imaging in the direction perpendicular to the plates. The optimization process was undertaken through simulation with CST Micro Wave Studio, followed by experiment. A 400 μm capillary tube, filled with doped water, was used for testing the optimized probe in a 2.4 T magnet. It is shown that increasing the width of the copper leads connected to the plates increases the homogeneity of the B1 magnetic field by almost 90%. The best approach to increase the sensitivity and the homogeneity of the probe was to maintain the dimensions of the plates and copper leads but to add additional capacitors at the corners to distribute the current. This approach produces a 40% stronger B1 magnetic field and increases the homogeneity by almost 85%. The experimental B1 magnetic field of the parallel‐plate prototype agrees within 20% of the value found through simulation, for specified power. The experimental MRI results show that it is possible to achieve a nominal resolution of 10 μm between the plates for suitable samples using the optimized probe. The optimized parallel‐plate resonator, combined with a phase encode SE SPI method, may be used for high resolution studies of lithium‐ion transport in the electrolyte solution of lithium‐ion batteries.
关键词： lithium-ion battery,optimization,MRI,parallel-plate resonator
更新于2025-09-23 15:23:52
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In Situ Measurement of Phase Boundary Kinetics during Initial Lithiation of Crystalline Silicon through Picosecond Ultrasonics
摘要： Studying the kinetics of phase transformation and phase boundary propagation during initial lithiation of silicon electrodes in lithium ion batteries is relevant to understanding their performance. Such studies are usually challenging due to the difficulties in measuring the phase boundary velocity in the interior of the sample. Here we introduce a non-invasive, in situ method to measure the progression of the phase boundary in a planar specimen geometry while maintaining well-controlled lithium flux and potential. We developed an apparatus integrating an electrochemical cell with picosecond ultrasonics to probe the propagating phase boundary in real time. Phase propagation during initial lithiation of crystalline silicon, which is an example of a high capacity anode, is investigated. The primary objective of this manuscript is to report on the experimental technique development and some preliminary results. For lithiation normal to the (100) plane, we observe the phase boundary velocity to be approximately 12 pm/s and x to be 3.73 in LixSi under galvanostatic lithiation with a current density of 40 μA/cm2. The growth rate of the lithiated phase and the reaction rate coefficient are examined using a Deal-Grove type model.
关键词： Lithium ion battery,In situ,Phase boundary propagation,Crystalline silicon,Picosecond ultrasonics
更新于2025-09-23 15:23:52
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Probing Electrolyte Solvents at Solid/Liquid Interface Using Gap-Mode Surface-Enhanced Raman Spectroscopy
摘要： Understanding the aprotic solution structures at the immediate vicinity of solid/liquid interface (SLI) is critically important for next generation lithium ion battery development. Yet, it is still challenging to investigate the carbonate chemical profiles close to the diffuse layer (about 10 nm) of the electrical double layer at SLI due to the lack of a ultrahigh surface sensitive tool. In this work, we demonstrate the structures of commonly used carbonate solvents (ethylene carbonate (EC) and diethyl carbonate (DEC)) and a carbonate additive (fluoroethylene carbonate (FEC)) in a commercial Li-ion battery electrolyte can be determined at ～17 nm above the electrode surface. This is only enabled by a nanogap surface-enhanced Raman spectroscopy (SERS) technique based on a monolayer gold nanoparticle (Au NP) ensemble. The SERS enhancement factor (EF) of those carbonates was found to depend on the molecular polarizability, with the maximum EF at ～105 found for EC and FEC. Despite their alike chemical structures, this monolayer Au NP SERS substrate is fully capable of discrimiating the different Raman finger prints of EC and FEC. Compared to EC, several vibration modes in FEC, such as C-C skeletal deformation, ring breathing band and C=O stretching band, shift to higher frequencies because of the displacement of a hydrogen atom by a much heavier fluorine atom in a methylene bridge. This counterintuitive observation against the commonly used “ball and spring” model in vibrational spectroscopy is mostly due to the increased bond strength in the FEC ring versus that of EC. A second order empirical polynomial best describes the correlation between the SERS band integration of EC or DEC molar concentration. Our findings open up new opportunities for in-depth understanding of the electrolyte molecular vibrational behaviors at direct solid/liquid interface and developing advanced electrolytes for next generation lithium-ion batteries.
关键词： carbonate solvents,electrolyte,solid/liquid interface,lithium-ion battery,surface-enhanced Raman spectroscopy
更新于2025-09-23 15:22:29
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Metaheuristic <i>Ab Initio</i> Optimum Search for Doping Effects in Nanocarbons
摘要： We have developed a combined approach of metaheuristic optimization algorithms (MOA), such as the genetic algorithm, with an ab-initio materials simulation engine. Concurrent run of the ab-initio calculations with each different parameter set selected by the MOA searches the optimum condition within a given input-parameter space. Using this methodology, the optimum dopant and its position/structure at a graphene edge are found to be a multiple N-atoms doping at graphitic sites, which predicts to lead to better charging/discharging performance when it is used as an anode material of Li-ion battery.
关键词： genetic algorithm,lithium-ion battery,nano-carbon,ab-initio simulation,doping effect
更新于2025-09-23 15:22:29
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Electrochemical and Structural Investigation on Ultrathin ALD ZnO and TiO <sub/>2</sub> Coated Lithium-Rich Layered Oxide Cathodes
摘要： Ultrathin coatings (1.5 ± 0.3 nm) of titanium dioxide and zinc oxide were deposited on lithium-rich layered oxide cathodes (Li1.2Mn0.6Ni0.2O2, LLO) by atomic layer deposition (ALD). The structures, electrochemical performances, and thermal stabilities of these coatings were investigated. An ultrathin uniform coating was obtained for TiO2 but not for ZnO because of di?erences in the layer growth mechanism. Regarding the initial charge?discharge curves under a current density of 0.04 C rate, the TiO2 coated samples exhibited a higher discharge capacity, 242 mAhg?1, compared with the ZnO coated samples, 220 mAhg?1, or the pristine samples, 228 mAhg?1. Both coated samples exhibited more stable cycling performance and thermal stability than the pristine samples. After 80 cycles under 0.5 C rate, the TiO2 and ZnO coated samples were found to have higher capacity retention (～94% and 78%, respectively) than the pristine samples (68%). The reaction temperature of the exothermic peak of the TiO2 and ZnO coated samples at 4.8 V shifted to 280 °C with heat release of 88.7 J/g for TiO2 and 270 °C with heat release of 154.6 J/g for ZnO. This is compared with an exothermic peak at 258 °C with heat release of 253.5 J/g for the pristine sample. In particular, an enhanced rate capability was only observed for the TiO2 coated samples. When the current densities were higher than 2 C rate, the TiO2 coated samples exhibited superior capacities than the pristine and ZnO coated samples. At a current density of 5 and 10 C rate, the capacities were found to be 120 and 95 mAhg?1. The improved electrochemical performances were mainly attributed to lower resistance ?lm. This feature lead to more preactivation of the charge transfer, which resulted from the layer morphology of the TiO2 LLO, smoother electron transport, and suppression of more side reactions, when compared with the island structure of the ZnO ?lm.
关键词： ZnO,Cathode,Atomic layer deposition,Lithium-rich layered oxides,TiO2,Lithium ion battery
更新于2025-09-23 15:21:21
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[IEEE 2018 International Power Electronics Conference (IPEC-Niigata 2018 –ECCE Asia) - Niigata, Japan (2018.5.20-2018.5.24)] 2018 International Power Electronics Conference (IPEC-Niigata 2018 -ECCE Asia) - Green Base Station Using Robust Solar System and High Performance Lithium ion battery for Next Generation Wireless Network (5G) and against Mega Disaster
摘要： To secure wireless communication services, we are researching and developing disaster-resistant and environmentally friendly green base stations. One effective disaster countermeasure in carriers is to make backup time long for base stations during a power outage. Therefore, we have developed a photovoltaics (PV) system for green base stations to prolong the backup. In this paper, we propose a power control method that realizes long-term autonomous operation by PV and lithium-ion batteries (LiB) and regeneration operation by only PV for when commercial power is lost during a power outage and describe the results obtained at field test station.
关键词： Lithium- ion battery,Green Base Station
更新于2025-09-23 15:21:21
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[IEEE 2019 IEEE 9th International Conference on Consumer Electronics (ICCE-Berlin) - Berlin, Germany (2019.9.8-2019.9.11)] 2019 IEEE 9th International Conference on Consumer Electronics (ICCE-Berlin) - Case Study of Photovoltaic Energy Surplus Absorption by Charging Lithium-Ion Batteries Considering Chargea??Discharge Energy Efficiency
摘要： In Autumn 2018, reductive control of photovoltaic surplus energy was performed in Kyushu, Japan. This was a lost opportunity to utilize renewable energy, which could have been otherwise stored in rechargeable batteries. In this study, we simulated the absorption of the photovoltaic energy surplus by charging battery systems of a working electric vehicle considering the energy efficiency of lithium-ion battery systems to reduce the operation cost. This study clarified the quantitative effects of a real-time energy efficiency diagnosis of lithium-ion battery systems. From the simulation results, we discovered that the improvements of the charge–discharge energy loss and the economic gain of the photovoltaic energy surplus absorption depended on the input–output power of the bidirectional vehicle- to-grid charger and the amount of surplus energy. When the input–output power is sufficiently high and the ratio of surplus energy to total capacity of the battery systems is sufficiently low, is the reasonable. The real-time degradation diagnosis of the battery systems and selection considering charge–discharge energy efficiency is necessary to improve the profit from surplus energy absorption.
关键词： charge – discharge energy efficiency,Lithium-ion battery,degradation diagnosis,photovoltaic surplus energy,working electric vehicle
更新于2025-09-23 15:21:01
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Mechanistic Origin of the High Performance of Yolk@Shell Bi2S3@N-Doped Carbon Nanowire Electrodes
摘要： High-performance lithium-ion batteries are commonly built with the heterogeneous composite electrodes that combine multiple active components for serving various electrochemical and structural functions. Engineering these heterogeneous composite electrodes toward drastically improved battery performance is hinged on a fundamental understanding of the mechanisms of multiple active components and their synergy or tradeoff effects. Herein, we report a rational design, fabrication, and understanding of yolk@shell Bi2S3@N-doped mesoporous carbon (C) composite anode, consisting of a Bi2S3 nanowire (NW) core within a hollow space surrounded by a thin shell of N-doped mesoporous C. This composite anode exhibits desirable rate performance and long cycle stability (700 cycles, 501 mAhg-1 at 1.0 Ag-1, 85% capacity retention). By in-situ transmission electron microscopy (TEM), X-ray diffraction, and NMR experiments and computational modeling, we elucidate the dominant mechanisms of the phase transformation, structural evolution, and lithiation kinetics of the Bi2S3@C NW anode. Our combined in-situ TEM experiments and finite-element simulations reveal that the hollow space between the Bi2S3-NW core and carbon shell can effectively accommodate the lithiation-induced expansion of Bi2S3-NWs without cracking C shells. This work demonstrates an effective strategy of engineering the yolk@shell-architectured anodes and also sheds light onto harnessing the complex multistep reactions in metal sulfides to enable high-performance lithium-ion batteries.
关键词： multiple computational modeling,lithiation mechanism,in-situ experiments,yolk@shell composite anode,lithium-ion battery
更新于2025-09-23 15:21:01
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In situ forming of ternary metal fluoride thin films with excellent Li storage performance by pulsed laser deposition
摘要： In the field of lithium ion battery, conversion-based metal fluoride cathodes are attractive for their excellent theoretical capacity and high voltage. However, the utilization of binary metal fluorides is severely hindered by irreversibility and large voltage hysteresis. The introduction of ternary metal fluorides, like AgCuF3 and CuxFe1-xF2, brings hope to address these shortcomings. To better understand the basic mechanism of conversion reaction in ternary metal fluoride cathodes, the Cu–Fe–F (CFF) thin films were successfully grown in situ by pulsed laser deposition in this work. The physico-chemical properties and electrochemical performance were discussed. Such a CFF solid solution phase presented great cycle stability (82% capacity remains after 100 cycles at current density of 285 mA g?1) and higher energy efficiency (71.8%), which can be attributed to the reversible structural rearrangement after the delithiation process disclosed by ex situ XPS, high-resolution TEM, and selected-area electron diffraction.
关键词： Thin film,Ternary metal fluoride,Lithium ion battery,Pulsed laser deposition
更新于2025-09-23 15:19:57