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- 2019
- Mach Zehnder Interferometer
- Convolution code
- Lithium Niobate
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- Electro-optic
- Optoelectronic Information Science and Engineering
- DIT University
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Solvation Structure Analysis of Lithium Ion in Concentrated Lithium Salt Solutions Using Raman Spectroscopy; ラマン分光法によるリチウム塩濃厚電解液中のイオン溶媒和構造解析;
摘要： Electrolyte solutions are one of the key liquid materials in the development of high-performance lithium-ion batteries (LIBs). Recently, a new concept, “superconcentrated electrolyte”, i.e., solvent-in-salt in liquid state, was proposed and widely investigated in terms of not only electrochemistry, but also physical chemistry and/or solution chemistry. In this work, we report on a structural study of lithium-ion complexes in highly salt-concentrated electrolytes, lithium bis(trifluoromethanesulfonyl)amide (LiTFSA) salt in N,N-dimethylpropionamide (DMPA), using Raman spectroscopy with the aid of density functional theory (DFT) calculations. In the range of the Li salt concentration, c Li = 0 – 3.2 mol dm–3, the individual solvation numbers of DMPA and TFSA species around Li ions [n (DMPA) and n (TFSA), respectively] were quantitatively determined and the relation between the Li ion complex structure and c Li was discussed at the molecular level.
关键词： raman spectroscopy,ion solvation,lithium-ion batteries,salt-concentrated electrolytes
更新于2025-09-19 17:15:36
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Ultrasensitive Field‐Effect Biosensors Enabled by the Unique Electronic Properties of Graphene
摘要： Using Li metal-free anodes for lithium-ion oxygen and lithium-ion sulfur batteries is considered as a promising solution to resolve the hazard of Li metal anode. Although Si anode exhibits high capacity and low electrochemical potential, it cannot match with oxygen (or sulfur) cathode, because both lack cycleable lithium ions. In this work, a free-standing and fibrous Si/C anode is prepared by electrospinning and its simple but effective lithiation is proposed. When assembling the cells, the free-standing Si/C anode was put between mass-controlled lithium metal foil and separator, and then the Si/C anode could be lithiated after adding electrolytes. By optimizing a LiFSI based ether electrolyte, the Si/C anode could achieve good cycleablity comparable to that in carbonate electrolytes. The lithiated SieO2 cells exhibit better cycling stability than the lithium oxygen cells with gel polymer electrolye. Moreover, because both Si anode and S@pPAN cathode are compatible with carbonate electrolytes, exceptional cycling performance has been achieved for the lithiated SieS cells. This simple method could pave the way to commercial applications of lithium-ion oxygen and lithium-ion sulfur batteries.
关键词： Lithium-sulfur battery,Lithium-oxygen battery,LieSi alloy anode,In-situ lithiation,Fibrous Si/C anode
更新于2025-09-19 17:13:59
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Research on optimum slowly-rising driver for electro-optic Q-switched laser
摘要： Electro-optic Q-switch drivers that based on pulse transformer method have been widely used in laser engineering because of the advantages of concise circuits, low supply voltage, low lost, etc., but the long rise time and short pulse duration of the high voltage (HV) pulses have a considerable effect on the Q-switched laser outputs. In this paper, we experimentally investigated the dependence of Q-switched laser outputs on the rise rate of slowly-rising HV pulses in a flash pumped Nd:YAG laser with variable cavity lengths. LiNbO3 Q-switches with various dimensions were used. Based on the experiment results, the optimum slowly-rising HV pulses for any EO Q-switched laser were derived, the only requirement is that voltage near dynamic quarter-wave voltage during the emission of laser pulses. Additionally, the optimum outputs were found to be consistent with the results obtained by using a rapid-switching driver with a rise time of 7 ns. The optimum range of applied voltage was determined to be 0.88 – 1.12 times dynamic quarter-wave voltage.
关键词： Electro-optic Q-switching,Lithium niobate crystal,Slow rise time,Q-switch driver,Pulsed laser
更新于2025-09-19 17:13:59
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Femtosecond Laser Processing of Thick Film Cathodes and Its Impact on Lithium-Ion Diffusion Kinetics
摘要： Quantitative experiments of lithiation/delithiation rates were considered for a better understanding of electrochemical intercalation/deintercalation processes in laser structured thick film cathodes. Besides galvanostatic cycling for evaluation of specific discharge capacities, a suitable quantitative approach for determining the rate of Li-ion insertion in the active material and the rate of Li-ion transport in the electrolyte is expressed by chemical diffusion coefficient values. For this purpose, the galvanostatic intermittent titration technique has been involved. It could be shown that laser structured electrodes provide an enhanced chemical diffusion coefficient and an improved capacity retention at high charging and discharging rates.
关键词： diffusion coefficient,LiCoO2,lithium-ion batteries,3D battery,laser ablation
更新于2025-09-19 17:13:59
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Electro-optically tunable racetrack dual microring resonator with a high quality factor based on a Lithium Niobate-on-insulator
摘要： We propose and analyse a novel electro-optically tunable racetrack dual microring resonator with a high Q factor based on a lithium niobate-on-insulator. Using the transfer matrix method, the field transmission and attenuation of the resonator are comparatively investigated to obtain optimised coupling parameters. The enhanced Q value at the resonant wavelength of the inner ring can reach 3.873 × 106, and the blue shift of the resonant wavelength is approximately 16 nm when the applied voltages fall in a ±150 V range resulting in an electro-optic tuning rate of 0.0526 nm/V. The designed resonator presented here exhibits high performance and may offer more potential applications for lithium niobate nanophotonic devices.
关键词： electro-optic effect,lithium niobate-on-insulator,optical microring resonator,quality factor
更新于2025-09-19 17:13:59
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Graphite lithiation and capacity fade monitoring of lithium ion batteries using optical fibers
摘要： Increasing the e?ciency and safety of battery management systems may require internal monitoring of lithium ion batteries. In this work, we present an analysis of the interaction between ?ber-optic evanescent wave sensors (FOEWS) and graphite particles within a lithium ion battery over multiple cycles. Through slow charging and long rest periods, the FOEWS signal has shown sensitivity to lithium concentration at the surface of graphite particles by demonstrating a response to the slow di?usion of lithium ions within graphite particles during rest periods (i.e. relaxation of the electrode). The slope of the FOEWS signal during a full charge is found to exhibit three distinct peaks that occur within lithiated graphite's stage transitions zones IV, III and II. Deviation from the observed three peak trend correlates with signi?cant battery capacity fade and thus indicate the sensors ability to detect capacity fade in real-time. During experiments, signi?cant deviations in the slope during charging occurred at about ~5% SOC and minor disturbances to the slope were observed at ~80% SOC, which supports limiting the depth of charge and discharge to avoid accelerated capacity fade. These results deepen our understanding of the FOEWS's interaction with lithium ion batteries and supports the development of algorithms that optimize the control and monitoring of graphite lithiation with the aim of achieving safer operation as well as maximizing capacity and battery life.
关键词： Optical ?ber sensor,Lithium ion battery,State of charge,Graphite,Capacity fade,Signal analysis
更新于2025-09-19 17:13:59
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A Hierarchical Three-Dimensional Porous Laser-Scribed Graphene Film for Suppressing Polysulfide Shuttling in Lithiuma??Sulfur Batteries
摘要： Lithium-sulfur (Li-S) battery is a promising next-generation rechargeable battery with high energy density. Given the outstanding capacities of sulfur (1675 mAh g?1) and lithium metal (3861 mAh g?1), Li-S battery theoretically delivers an ultra-high energy density of 2567 Wh kg?1. However, this energy density cannot be realized due to several factors, particularly the shuttling of polysulfide intermediates between the cathode and anode, which causes serious degradation of capacity and cycling stability of a Li-S battery. In this work, a simple and scalable route was employed to construct a free-standing laser scribed graphene (LSG) interlayer which effectively suppresses the polysulfide shuttling in Li-S batteries. Thus, a high specific capacity (1160 mAh g-1) with excellent cycling stability (80.4% capacity retention after 100 cycles) has been achieved due to the unique structure of hierarchical three-dimensional pores in the free-standing LSG.
关键词： High-capacity,Lithium-sulfur battery,Graphene,Polysulfide shuttling,Interlayer,Laser Scribed Graphene
更新于2025-09-19 17:13:59
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Quantitative spatially resolved <i>post-mortem</i> analysis of lithium distribution and transition metal depositions on cycled electrodes <i>via</i> a laser ablation-inductively coupled plasma-optical emission spectrometry method
摘要： Diminishing the loss of performance of lithium ion batteries (LIBs) is a challenge that is yet to be ful?lled. Understanding of deterioration processes and mechanisms (i.e., so-called aging) requires analytically accurate examination of aged cells. Changes in the distribution of lithium or transition metals in the LIB cells can in?uence their cycle and calendar life signi?cantly. As electrochemically treated cells and especially their electrodes do not age homogeneously and the local electrochemistry (e.g. deposition patterns) is strongly dependent on surface properties, bulk analysis is not a satisfactory investigation method. Therefore, a surface sensitive method, namely laser ablation-inductively coupled plasma-optical emission spectrometry (LA-ICP-OES) is presented. LIB cells with lithium metal oxide LiNi1/3Co1/3Mn1/3O2 (NCM111) as cathode material and graphite as anode material are investigated using a 213 nm Nd:YAG laser.
关键词： graphite,aging,laser ablation-inductively coupled plasma-optical emission spectrometry,NCM111,LA-ICP-OES,LIBs,Nd:YAG laser,lithium ion batteries
更新于2025-09-19 17:13:59
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Three-dimensional polarization ray tracing in electro-optic crystals
摘要： Electro-optic crystals are extensively utilized to manipulate polarized light. In this paper, a general and accurate three-dimensional polarization ray tracing calculus for characterizing the evolution of polarization state in electro-optic crystals is reported for the first time. The analytical formulas of the parameters describing the propagation properties of the light passing through an electro-optical crystal with an arbitrary incident direction are derived. The partial interference between the divergent light beams is considered in the proposed calculus. Both experiments and calculations on an electro-optic modulator based on a lithium niobate crystal over the azimuth angle of 0?-360? and the incidence angle of 0?-3? are presented as an example. The experimental results show very good agreement with the theoretical results.
关键词： Polarization,Electro-optic crystals,Lithium niobate,Ray tracing
更新于2025-09-19 17:13:59
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The Effect of Lithium‐Doping in Solution‐Processed Nickel Oxide Films for Perovskite Solar Cells
摘要： The effect of substitutional Li doping into NiOx hole transporting layer (HTL) for use in inverted perovskite solar cells was systematically studied. Li doped NiOx thin films with preferential crystal growth along the (111) plane were deposited using a simple solution-based process. Mott-Schottky analysis showed that hole carrier concentration (NA) is doubled by Li doping. Utilizing 4% Li in NiOx improved the power conversion efficiency (PCE) of solar devices from 9.0% to 12.6%. Photoluminescence quenching investigations demonstrate better hole capturing properties of Li:NiOx compared to that of NiOx, leading to higher current densities by Li doping. The electrical conductivity of NiOx is improved by Li doping. Further improvements of the device were made by using an additional ZnO layer onto PCBM, to remove shunt paths, leading to a PCE of 14.2% and a fill factor of 0.72.
关键词： nickel oxide,lithium doping,hole transporting layer,inverted perovskite solar cells
更新于2025-09-19 17:13:59