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Lattice and spin dynamics in multiferroic BiFeO3 and RMnO3

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National Science Review 2019年第4期6卷 642-652页

作者： Yan Song Ben Xu ce-wen nan School of Materials Science and Engineering and State Key Laboratory of New Ceramics and Fine ProcessingTsinghua University

The multiferroic materials Bi Fe O3 and RMn O3 exhibit coexisting magnetic order and ferroelectricity, and provide exciting platforms for new physics and potentially novel devices, where intriguing interplay between phonons and magnons exists. In this review, we paint a complete picture of bulk BiFeO3together with orthorhombic and hexagonal RMnO3（R includes rare-earth elements and yttrium） by summarizing the dynamics of spin and lattice and their magnetoelectric coupling, as well as the methods of controlling these characteristics under non-equilibrium conditions, from experimental and simulation perspectives.

关键词： multiferroics phonon magnon

Perspective: voltage control of magnetization in multiferroic heterostructures

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National Science Review 2019年第4期6卷 621-624页

作者： Jia-Mian Hu ce-wen nan Long-Qing Chen Department of Materials Science and Engineering University of Wisconsin–Madison State Key Lab of New ceramics and Fine Processing School of Materials Science and Engineering Tsinghua University Department of Materials Science and Engineering Pennsylvania State University

Multiferroic materials host ferromagnetic and ferroelectric orders either in the same phase, or separately in distinct magnetic and ferroelectric phases. In some multiferroic materials, the two distinct ferroic orders can be strongly coupled (namely, magnetoelectric coupling)[1], which can be exploited for achieving new functionalities. For example, it allows for controlling magnetization with a voltage rather than a magnetic-field-generating electric current, providing an energy-efficient

关键词： Perspective voltage control of magnetization in multiferroic heterostructures AFM

Ferroelectricity and multiferroicity： Broader way to go beyond

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Frontiers of physics 2012年第4期7卷 373-374页

作者： Jun-Ming Liu ce-wen nan Department of Physics Nanjing University Nanjing 210093 China Department of Materials Science and Engineering Tsinghua University Beijing 100084 China

Ferroelectrics and magnetics represent two major classes of functional materials which peo- ple find everywhere in daily life, though they are usually beyond the views of people and hidden inside the hearts of most devices. While spintronies [1] comes into being, reviving magnetism which has been as old as ferroelectricity, since decades ago the physics of fer- roeleetries has turned its attention to the domain scale from the atomic level at which the physics was believed to be well understood [2]. As is well known, it is a small world, and ferroelectricity finally has its marriage with magnetism at a proper time [3], giving birth to multiferroicity, a concurrent and aggressive field of condensed matter physics where both ferroelectricity and magnetism can find their fans [4]. Consequently, multiferroicity bridges ferroelectricity and magnetism in an extraordinary manner, generating a number of novel phenomena and raising a pocket of key issues.

关键词： condensed matter physics functional materials atomic level small world

Strategies to suppress the shuttle effect of redox mediators in lithium-oxygen batteries

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Journal of Energy Chemistry 2021年第9期30卷 135-149页

作者： Xinbin Wu Wei Yu Kaihua wen Huanchun Wang Xuanjun Wang ce-wen nan Liangliang Li State Key Laboratory of New ceramics and Fine Processing School of Materials Science and EngineeringTsinghua University100084 BeijingChina High-Tech Institute of Xi’an Xi’anChina

Rechargeable lithium-oxygen(Li-O_(2))batteries are the next generation energy storage devices due to their ultrahigh theoretical *** mediators(RMs)are widely used as a homogenous electrocatalyst in non-aqueous Li-O_(2)batteries to enhance their discharge capacity and reduce charge ***,the shuttle effect of RMs in the electrolyte solution usually leads to corrosion of the Li metal anode and uneven Li deposition on the anode surface,resulting in unwanted consumption of electrocatalysts and deterioration of the *** is therefore necessary to take some measures to prevent the shuttle effect of RMs and fully utilize the soluble ***,we summarize the strategies to suppress the RM shuttle effect reported in recent years,including electrolyte additives,protective separators and electrode *** mechanisms of these strategies are analyzed and their corresponding requirements are *** electrochemical properties of Li-O_(2)batteries with different strategies are summarized and *** challenges and perspectives on preventing the shuttle effect of RMs are described for future *** review provides guidance for achieving shuttle-free redox mediation and for designing Li-O_(2)cells with a long cycle life,high energy efficiency and highly reversible electrochemical reactions.

关键词： Lithium-oxygen battery Redox mediator Shuttle effect Electrolyte additive Protective separator

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Electrochemical performance of Li-rich cathode material,0.3Li_2MnO_3-0.7LiMn_(1/3)Ni_(1/3)Co_(1/3)O_2 microspheres with F-doping

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Rare Metals 2019年第3期38卷 189-198页

作者： Ting Liu Shi-Xi Zhao Lu-Lu Gou Xia Wu ce-wen nan Graduate School at Shenzhen Tsinghua University School of Materials Science and Engineering Tsinghua University

Layered F-doped cathode materials 0.3 Li_2 MnO_3-0.7 LiMn_(1/3)Ni_(1/3)CO_(1/3))O_(2-x)F_x(x = 0, 0.01, 0.02, 0.03, 0.04,0.05) microspheres made up of nanosized primary grains were prepared through co-precipitation method. The sample of x = 0.02 demonstrates a large discharge capacity of226 mAh g^(-1) over 100 cycles at 0.1 C and excellent rate performance with discharge capacity of 96 mAh g-1 at 5.0 C and room temperature. Particularly, this material shows much enhanced electrochemical performances even at high temperature of 55 ℃. It delivers a quite high discharge capacity of 233.7 mAh·g^(-1) at 1.0 C with capacity retention as high as 97.9% after 100 cycles. The results demonstrate that the fluorine incorporation stabilizes the cathode structure and maintains stable interfacial resistances.

关键词： Lithium-ion battery Cathode materials 0.3Li2MnO3-0.7LiMn1/3Ni1/3Co1/3O2-xFx F-doped

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Self-etching Ni-Co hydroxides@Ni-Cu nanowire arrays with enhancing ultrahigh areal capacitance for flexible thin-film supercapacitors

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Rare Metals 2017年第9期36卷 691-697页

作者： Peng Guo Yang Shen Yu Song Jing Ma Yuan-Hua Lin ce-wen nan State Key Laboratory of New ceramics and Fine Processing School of Materials Science and EngineeringTsinghua UniversityBeijing 100084China Laboratory of Advanced Energy Storage Materials and Devices Research Institute of Tsinghua University in ShenzhenShenzhen 518057China

Flexible thin-film supercapacitors with high specific capacitance are highly desirable for modern wearable or micro-sized electrical and electronic applications. In this contribution, Ni-Co hydroxides（NCH）nanosheets were deposited on top of Ni-Cu alloy（NCA）nanowire arrays forming a freestanding thin-film composite electrode with hierarchical structure for *** electrochemical cycling, the dissolution of Cu into Cu ions will create more active sites on NCA, and the redeposited copper oxide can be coated onto NCH, giving rise to substantial increase in specific capacitance with cycling. Meanwhile, NCA and NCH have excellent conductivity, thus leading to excellent rate performance. This flexible thin-film electrode delivers an ultrahigh initial specific capacitance of 0.63 F·cm^（-2）（or 781.3 F·cm^（-3））.During charge-discharge cycles, the specific capacitance can increase up to 1.18 F·cm^（-2）（or 1475 F·cm^（-3）） along with the“self-etching”process. The electrode presents a better specific capacitance and rate capability compared with previously reported flexible thin-film electrode, and this novel design of etching technique may expand to other binary or ternary materials.

关键词： Nickel Cobalt Copper Hydroxides Supercapacitors

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nanonet-/fiber-structured flexible ceramic membrane enabling dielectric energy storage

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Journal of Advanced ceramics 2023年第1期12卷 145-154页

作者： Lvye DOU Bingbing YANG Shun LAN Yiqian LIU Yuan-Hua LIN ce-wen nan State Key Laboratory of New ceramics and Fine Processing School of Materials Science and EngineeringTsinghua UniversityBeijing 100084China

ceramics are considered intrinsically brittle at macro scale due to the lack of slip mechanism and pre-existing defects,which greatly limits their potential applications in emerging fields including wearable electronic devices and flexible *** this contribution,we developed BiFeO_(3)/SiO_(2) dual-networks with exceptional flexibility through a coupled electronetting/electrospun *** hybrid nanostructured networks endow the material with high tensile strength(2.7 MPa),excellent flexibility(80%recoverable deformation),and robust fatigue resistance performance(maintain flexibility after a 1000-cyclic compress test).After in-situ compounded with dielectric polymer via a layer-by-layer solution casting method,the resultant three-dimensional(3D)composite film exhibits a twice higher dielectric constant(εr)than polyether imide(PEI)*** importantly,the breakdown strength of the 3D composite film is almost the same as that of the PEI film,resulting in an enhanced energy density of~6.0 J/cm^(3) and a high efficiency of 80%at 4.58 MV/*** unique structure,combined with the excellent balance between mechanical and dielectric properties in flexible structures,is of critical significance to the design of flexible functional ceramics and broadening their applications in wearable electric devices.

关键词： BiFeO_(3)/SiO_(2)dual-network flexible mechanically robust dielectric energy storage

Understanding and designing magnetoelectric heterostructures guided by computation:progresses,remaining questions,and perspectives

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npj Computational Materials 2017年第1期3卷 304-324页

作者： Jia-Mian Hu Chun-Gang Duan ce-wen nan Long-Qing Chen Department of Materials Science and Engineering Pennsylvania State UniversityUniversity ParkPA 16802USA Key Laboratory of Polar Materials and Devices Ministry of EducationEast China Normal UniversityShanghaiChina School of Materials Science and Engineering and State Key Lab of New Ceramics and Fine ProcessingTsinghua UniversityBeijing 100084China

Magnetoelectric composites and heterostructures integrate magnetic and dielectric materials to produce new functionalities,e.g.,magnetoelectric responses that are absent in each of the constituent materials but emerge through the coupling between magnetic order in the magnetic material and electric order in the dielectric *** magnetoelectric coupling in these composites and heterostructures is typically achieved through the exchange of magnetic,electric,or/and elastic energy across the interfaces between the different constituent materials,and the coupling effect is measured by the degree of conversion between magnetic and electric energy in the absence of an electric *** strength of magnetoelectric coupling can be tailored by choosing suited materials for each constituent and by geometrical and microstructural *** this article,we discuss recent progresses on the understanding of magnetoelectric coupling mechanisms and the design of magnetoelectric heterostructures guided by theory and *** outline a number of unsolved issues concerning magnetoelectric *** compile a relatively comprehensive experimental dataset on the magnetoelecric coupling coefficients in both bulk and thin-film magnetoelectric composites and offer a perspective on the data-driven computational design of magnetoelectric composites at the mesoscale microstructure level.

关键词： composites material coupling

A molecular sieve-containing protective separator to suppress the shuttle effect of redox mediators in lithium-oxygen batteries

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nano Research 2023年第7期16卷 9453-9460页

作者： Xinbin Wu Huiping Wu Shundong Guan Ying Liang Kaihua wen Huanchun Wang Xuanjun Wang ce-wen nan Liangliang Li State Key Laboratory of New ceramics and Fine Processing School of Materials Science and EngineeringTsinghua UniversityBeijing 100084China High-Tech Institute of Xi’an Xi’an 710025China

Lithium-oxygen(Li-O_(2))batteries have a great potential in energy storage and conversion due to their ultra-high theoretical specific energy,but their applications are hindered by sluggish redox reaction kinetics in the charge/discharge *** mediators(RMs),as soluble catalysts,are widely used to facilitate the electrochemical processes in the Li-O_(2)batteries.A drawback of RMs is the shuttle effect due to their solubility and mobility,which leads to the corrosion of a Li metal anode and the degradation of the electrochemical performance of the ***,we synthesize a polymer-based composite protective separator containing molecular *** nanopores with a diameter of 4Åin the zeolite powder(4A zeolite)are able to physically block the migration of 2,2,6,6-tetramethylpiperidinyloxy(TEMPO)molecules with a larger size;therefore,the shuttle effect of TEMPO is *** the assistance of the zeolite molecular sieves,the cycle life of the Li-O_(2)batteries is significantly extended from~20 to 170 cycles at a current density of 250 mA·g^(-1)and a limited capacity of 500 mAh·g^(-1).Our work provides a highly effective approach to suppress the shuttle effects of RMs and boost the electrochemical performance of Li-O_(2)batteries.

关键词： lithium-oxygen batteries redox mediators shuttle effects protective separators zeolite molecular sieves