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A flexible solid polymer electrolyte enabled with lithiated zeolite for high performance lithium battery

Nano Research 2023年第7期16卷 9443-9452页

作者： Zhiyu Ding Qiming Tang Qi Zhang Penghui Yao Xingjun Liu Junwei Wu Shenzhen Key Laboratory of Advanced Materials Department of Materials Science and EngineeringHarbin Institute of Technology(Shenzhen)Shenzhen 518055China Maryland Energy Innovation Institute University of MarylandCollege ParkMD 20742USA Department of Chemical and Metallurgical Engineering Aalto UniversityKemistintie 1Aalto FI-00076Finland

Solid-state lithium batteries using composite polymer electrolytes(CPEs)have attracted much attention owing to their higher safety compared to liquid electrolytes and flexibility compared to ceramic electrolytes.However,their unsatisfactory lithium-ion conductivity still limits their development.Herein,a high ion conductive CPE with multiple continuous lithium pathways is designed.This new electrolyte consists of poly(vinylidene fluorideco-hexafluoropropylene)(PVDF-HFP)and lithiated X type zeolite(Li-X),which possesses a high ionic conductivity(1.98×10^(-4)S/cm),high lithium transference number(t_(Li^(+))=0.55),wide electrochemical window(4.7 V),and excellent stability against the lithium anode.Density functional theory(DFT)calculation confirms that the Lewis acid sites in zeolite can graft with N,N-dimethylformamide(DMF)and PVDF-HFP chains,resulting in decreased crystallinity of polymer and providing rapid Li+transmission channels.When used in a full cell,the solid Li|Li-X-3%|LiFePO_(4) cell displays excellent cycling stability and rate performance at room temperature and 60℃.Furthermore,pouch cells with the Li-X-3%electrolyte exhibit brilliant safety under extreme conditions,such as folding and cutting.Thus,this proposed zeolite-PVDF-HFP CPE represents a promising potential in the application of making a safer,higher performing,and flexible solid-state lithium battery.

关键词： solid-state lithium batteries composite polymer electrolytes zeolite poly(vinylidene fluorideco-hexafluoropropylene)(PVDF-HFP) flexible

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Size controllable single-crystalline Ni-rich cathodes for high-energy lithium-ion batteries

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National Science Review 2023年第2期10卷 232-241页

作者： Ji-Lei Shi Hang Sheng Xin-Hai Meng Xu-Dong Zhang Dan Lei Xiaorui Sun Hongyi Pan Junyang Wang Xiqian Yu Chunsheng Wang Yangxing Li Yu-Guo Guo CAS Key Laboratory of Molecular Nanostructure and Nanotechnology Beijing National Laboratory for Molecular Sciences (BNLMS) Institute of Chemistry Chinese Academy of Sciences (CAS) University of Chinese Academy of Sciences Beijing Advanced innovation Center for Materials Genome Engineering Institute of PhysicsCAS Department of Chemical and Biomolecular Engineering University of Maryland Chery New energy Automobile Co. Ltd

A single-crystalline Ni-rich(SCNR) cathode with a large particle size can achieve higher energy density,and is safer,than polycrystalline counterparts.However,synthesizing large SCNR cathodes(>5 μm)without compromising electrochemical performance is very challenging due to the incompatibility between Ni-rich cathodes and high temperature calcination.Herein,we introduce Vegard’s Slope as a guide for rationally selecting sintering aids,and we successfully synthesize size-controlled SCNR cathodes,the largest of which can be up to 10 μm.Comprehensive theoretical calculation and experimental characterization show that sintering aids continuously migrate to the particle surface,suppress sublattice oxygen release and reduce the surface energy of the typically exposed facets,which promotes grain boundary migration and elevates calcination critical temperature.The dense SCNR cathodes,fabricated by packing of different-sized SCNR cathode particles,achieve a highest electrode press density of 3.9 g cm-3and a highest volumetric energy density of 3000 Wh L-1.The pouch cell demonstrates a high energy density of 303 Wh kg-1,730 Wh L-1and 76% capacity retention after 1200 cycles.SCNR cathodes with an optimized particle size distribution can meet the requirements for both electric vehicles and portable devices.Furthermore,the principle for controlling the growth of SCNR particles can be widely applied when synthesizing other materials for Li-ion,Na-ion and K-ion batteries.

关键词： lithium-ion baTheries high energy density Ni-rich cathodes single-crystalline surface energy

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Statistical variances of diffusional properties from ab initio molecular dynamics simulations

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npj Computational Materials 2018年第1期4卷 510-518页

作者： Xingfeng He Yizhou Zhu Alexander Epstein Yifei Mo Department of Materials Science and Engineering University of MarylandCollege ParkMD 20742USA Maryland Energy Innovation Institute University of MarylandCollege ParkMD 20742USA

Ab initio molecular dynamics(AIMD)simulation is widely employed in studying diffusion mechanisms and in quantifying diffusional properties of materials.However,AIMD simulations are often limited to a few hundred atoms and a short,sub-nanosecond physical timescale,which leads to models that include only a limited number of diffusion events.As a result,the diffusional properties obtained from AIMD simulations are often plagued by poor statistics.In this paper,we re-examine the process to estimate diffusivity and ionic conductivity from the AIMD simulations and establish the procedure to minimize the fitting errors.In addition,we propose methods for quantifying the statistical variance of the diffusivity and ionic conductivity from the number of diffusion events observed during the AIMD simulation.Since an adequate number of diffusion events must be sampled,AIMD simulations should be sufficiently long and can only be performed on materials with reasonably fast diffusion.We chart the ranges of materials and physical conditions that can be accessible by AIMD simulations in studying diffusional properties.Our work provides the foundation for quantifying the statistical confidence levels of diffusion results from AIMD simulations and for correctly employing this powerful technique.

关键词： technique materials. diffusion

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CFD-DEM simulation of fluorination reaction in fluidized beds with local grid and time refinement method

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Particuology 2024年第1期84卷 145-157页

作者： Mofan Qiu Lin Jiang Rongzhen Liu Yaping Tang Malin Liu institute of Nuclear and New energy Technology Collaborative Innovation Center of Advanced Nuclear Energy TechnologyTsinghua UniversityBeijing100084China

The gas-solid reaction process with wide particle size distribution is extensively used in the chemical engineering field,especially the particle reacts with the gas gradually,such as fluorination reactions in fluidized beds.When the computational fluid dynamics-discrete element method(CFD-DEM)is used for the coupling simulation of multiphase and polydisperse particle reaction system,the grid size directly affects the accuracy of flow field information and simulation of chemical reaction.Furthermore,particle calculation time step will directly affect the efficiency of coupling calculation.In this work,a local grid and time step refinement method is proposed to simulate multiphase and polydisperse particle fluid-ization reaction system.In this method,the refined DEM grids are automatically generated in the computational domain around the fine particles,and the detailed fluid phase information is obtained with the interpolation algorithm.In the two-phase coupling process,particles are divided into different groups based on physical properties,each group has its own independent time step.The multistage conical-cylindrical spouted bed is proposed for the fluorination reaction process;the operating gas ve-locity range of the polydisperse particle system is extended by the new design while the particle size distribution changes with the gas-solid reaction process.It is demonstrated that the local grid and time step refinement method can improve the accuracy and efficiency of the traditional CFD-DEM method in the reaction process simulation,which describes a polydisperse particle system with wide particle size distribution.Aimed at improving the simulation accuracy and efficiency,this paper will be helpful for simulating the particle reaction process in the gas-solid fluidized bed and beneficial for the development of the CFD-DEM method.

关键词： CFD-DEM Polydisperse particle Two-phase flow Fluidized bed

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CFD-DEM simulation of high density particles fluidization behaviors in 3D conical spouted beds

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Particuology 2024年第5期88卷 266-281页

作者： Lin Jiang Mofan Qiu Rongzheng Liu Bing Liu Youlin Shao Malin Liu institute of Nuclear and New energy Technology Collaborative Innovation Center of Advanced Nuclear Energy TechnologyTsinghua UniversityBeijing 100084China

The spouted bed has been used in the coating process of high-density nuclear fuel particle.The particle fluidization behaviors in pseudo-2D and 3D spouted beds were simulated and validated.The effects of four independent variables(cone angle,particle density,inlet gas velocity,and particle loading)on particle fluidization behaviors in the 3D spouted bed were investigated systematically.The cone angle effect on fluidization mechanism was studied quantitatively first time.A new fluidization quality index was proposed based on the particle entrainment principle,and an extreme value was obtained when the cone angle was 60°,considered to be the optimum value for the 3D conical spouted bed.It was indicated the gas–solid contact efficiency can be kept up if the gas velocity was proportional toρp 0.65 and N p 0.78 when the particle density or loading was increased.These results will be useful for geometry and operation parameters design of the 3D conical spouted bed and helpful for developing the fluidization mechanism of high-density particles.

关键词： Spouted bed High-density particle CFD-DEM Fluidization quality index Particle loading

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Numerical simulation of uranium tetrafluoride fluorination in a multistage spouted bed using the improved CFD-DEM chemical reaction model

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Particuology 2023年第4期75卷 119-136页

作者： Mofan Qiu Zhao Chen Lin Jiang Rongzhen Liu Yaping Tang Malin Liu institute of Nuclear and New energy Technology Collaborative Innovation Center of Advanced Nuclear Energy TechnologyTsinghua University.Beijing.100084China

A CFD-DEM reaction coupling model was established to simulate UF_(4) fluorination process,in which heat and mass transfer,heterogeneous chemical reaction,and particle shrinkage model were considered.The gas behavior was described by the conservation laws of mass,momentum,and energy.The solid phase is modeled with the discrete element method,considering the gas-solid interphase force,contact force,heat transfer,and chemical reaction models based on the discretized surface.Each particle can be individually tracked and associated with specific physical properties.The proposed CFD-DEM reaction coupling model based on particle shrinking reaction model with discretized surface was validated by the experimental and literature results at first.Then a multistage conical spouted bed was proposed and the process of UF_(4) fluoridation reaction in it was investigated.The fluidization characteristics and the con-centration distribution of gaseous products in the spouted bed with an extended gas velocity range were obtained and analyzed.In addition,the effects of different parameters,such as superficial gas velocity,temperature,fluorine concentration,on fluoridation rate and the fluorine conversion rate were inves-tigated based on the proposed CFD-DEM reaction coupling model.The results obtained in this work are beneficial for method development of the chemical reaction simulation research in particle scale using the CFD-DEM model,and useful for operation and equipment parameters design of the uranium tetra-fluoride fluorinate industrial process in the future.

关键词： CFD-DEM Particle shrinkage model Multistage spouted bed Uranium fluorination

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The pathway toward practical application of lithium-metal anodes for non-aqueous secondary batteries

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National Science Review 2022年第8期9卷 194-210页

作者： Panlong Li Zhong Fang Xiaoli Dong Congxiao Wang Yongyao Xia Department of Chemistry and Shanghai Key Laboratory of Molecular Catalysis and Innovative Materials Institute of New Energy iChEM (Collaborative Innovation Center of Chemistry for Energy Materials) Fudan University

The revolution of automotive vehicles(from petrol vehicles to electric vehicles) has set high demands for the performance of batteries. Lithium-metal batteries(LMBs) show great potential owing to their high energy density but encounter poor cycle life and safety issues. It is of great significance to reveal LMB failure mechanisms and understand their relationship with battery performance. This review presents an overview of the state-of-the-art Li-metal anodes, with an emphasis on two typical failure modes: capacity degradation and dendritic growth of Li metal. The critical correlations between the composition, structure and failure are explained point by point. The chemical and electrochemical stabilities of the lithium anode are discussed.Particularly, for the first time, five types of lithium-metal anodes are classified to develop a comprehensive understanding of LMBs. Furthermore, strategies are suggested to improve the practical performance of LMBs, including material innovation, electrolyte modification and advanced characterization.

关键词： lithium-metal anode failure mode concentration polarization dead Li

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Multi-mode microcavity frequency engineering through a shifted grating in a photonic crystal ring

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Photonics Research 2023年第11期11卷 I0009-I0016页

作者： XIYUAN LU YI SUN ASHISH CHANANA USMAN AJAVID MARCELO DAVANCO KARTIK SRINIVASAN Microsystems and Nanotechnology Division Physical Measurement LaboratoryNational Institute of Standards and TechnologyGaithersburgMaryland 20899USA Joint Quantum institute NIST/University of MarylandCollege ParkMaryland 20742USA

Frequency engineering of whispering-gallery resonances is essential in microcavity nonlinear optics.The key is to control the frequencies of the cavity modes involved in the underlying nonlinear optical process to satisfy its energy conservation criterion.Compared to the conventional method that tailors dispersion by cross-sectional geometry,thereby impacting all cavity mode frequencies,grating-assisted microring cavities,often termed as photonic crystal microrings,provide more enabling capabilities through mode-selective frequency control.For example,a simple single period grating added to a microring has been used for single frequency engineering in Kerr optical parametric oscillation(OPO)and frequency combs.Recently,this approach has been extended to multifrequency engineering by using multi-period grating functions,but at the cost of increasingly complex grating profiles that require challenging fabrication.Here,we demonstrate a simple approach,which we term as shifted grating multiple mode splitting(SGMMS),where spatial displacement of a single period grating imprinted on the inner boundary of the microring creates a rotational asymmetry that frequency splits multiple adjacent cavity modes.This approach is easy to implement and presents no additional fabrication challenges compared to an unshifted grating,and yet is very powerful in providing multi-frequency engineering functionality for nonlinear optics.We showcase an example where SGMMS enables OPO across a wide range of pump wavelengths in a normal-dispersion device that otherwise would not support OPO.

关键词： multifrequency mode shifted

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A hybrid spatial-temporal deep learning prediction model of industrial methanol-to-olefins process

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Frontiers of Chemical Science and Engineering 2024年第4期18卷 73-85页

作者： Jibin Zhou Xue Li Duiping Liu Feng Wang Tao Zhang Mao Ye Zhongmin Liu National Engineering Research Center of Lower-Carbon Catalysis Technology Dalian Institute of Chemical PhysicsChinese Academy of SciencesDalian 116023China Yulin innovation institute for Clean energy Clean Energy Innovation Institute of Chinese Academy of SciencesYulin 719053China Xuelang Industrial Intelligence Technology Co. Ltd.Wuxi 214000China

Methanol-to-olefins,as a promising non-oil pathway for the synthesis of light olefins,has been successfully industrialized.The accurate prediction of process variables can yield significant benefits for advanced process control and optimization.The challenge of this task is underscored by the failure of traditional methods in capturing the complex characteristics of industrial processes,such as high nonlinearities,dynamics,and data distribution shift caused by diverse operating conditions.In this paper,we propose a novel hybrid spatial-temporal deep learning prediction model to address these issues.Firstly,a unique data normalization technique called reversible instance normalization is employed to solve the problem of different data distributions.Subsequently,convolutional neural network integrated with the self-attention mechanism are utilized to extract the temporal patterns.Meanwhile,a multi-graph convolutional network is leveraged to model the spatial interactions.Afterward,the extracted temporal and spatial features are fused as input into a fully connected neural network to complete the prediction.Finally,the outputs are denormalized to obtain the ultimate results.The monitoring results of the dynamic trends of process variables in an actual industrial methanol-to-olefins process demonstrate that our model not only achieves superior prediction performance but also can reveal complex spatial-temporal relationships using the learned attention matrices and adjacency matrices,making the model more interpretable.Lastly,this model is deployed onto an end-to-end Industrial Internet Platform,which achieves effective practical results.

关键词： methanol-to-olefins process variables prediction spatial-temporal self-attention mechanism graph convolutional network

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Visualizing the role of applied voltage in non-metal electrocatalysts

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National Science Review 2023年第9期10卷 46-55页

作者： Ziyuan Wang Jun Chen Chenwei Ni Wei Nie Dongfeng Li Na Ta Deyun Zhang Yimeng Sun Fusai Sun Qian Li Yuran Li Ruotian Chen Tiankai Bu Fengtao Fan Can Li Collaborative innovation Center of Chemistry for energy Materials (iChEM) State Key Laboratory of Catalysis Dalian National Laboratory for Clean EnergyDalian Institute of Chemical PhysicsChinese Academy of Sciences 2. Department of ChemistryCollaborative Innovation Center of Chemistry for Energy Materials (iChEM)College of Chemistry and Chemical Engineering Xiamen University energy College University of Chinese Academy of Sciences Department of Materials Imperial College London

Understanding how applied voltage drives the electrocatalytic reaction at the nanoscale is a fundamental scientific problem,particularly in non-metallic electrocatalysts,due to their low intrinsic carrier concentration.Herein,using monolayer molybdenum disulfide(MoS2) as a model system of non-metallic catalyst,the potential drops across the basal plane of MoS2(△Vsem) and the electric double layer(△Vedl)are decoupled quantitatively as a function of applied voltage through in-situ surface potential microscopy.We visualize the evolution of the band structure under liquid conditions and clarify the process of EFkeeping moving deep into Ec, revealing the formation process of the electrolyte gating effect.Additionally,electron transfer(ET) imaging reveals that the basal plane exhibits high ET activity,consistent with the results of surface potential measurements.The potential-dependent behavior of kfand nsin the ET reaction are further decoupled based on the measurements of △Vsemand △Vedl.Comparing the ET and hydrogen evolution reaction imaging results suggests that the low electrocatalytic activity of the basal plane is mainly due to the absence of active sites,rather than its electron transfer ability.This study fills an experimental gap in exploring driving forces for electrocatalysis at the nanoscale and addresses the long-standing issue of the inability to decouple charge transfer from catalytic processes.

关键词： non-metal electrocatalyst surface potential electron transfer hydrogen evolution reaction mapping

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