Advanced preparation and application of bimetallic materials in lithium-sulfur batteries:A review

Lithium-sulfur(Li-S)batteries are considered highly promising as next-generation energy storage systems due to high theoretical capacity(2600 Wh kg^(-1))and energy density(1675 mA h g^(-1))as well as the abundant natural reserves,low cost of elemental sulfur,and environmentally friendly properties.However,several challenges impede its commercialization including low conductivity of sulfur itself,the severe“shuttle effect”caused by lithium polysulfides(LiPSs)during charge–discharge processes,volume expansion effects and sluggish reaction kinetics.As a solution,polar metal particles and their compounds have been introduced as the main hosts for sulfur cathode due to their robust catalytic activity and adsorption capability,effectively suppressing the“shuttle effect”of Li PSs.Bimetallic alloys and their compounds with multi-functional properties exhibit remarkable electrochemical performance more readily when compared to single-metal materials.Well-designed bimetallic materials demonstrate larger specific surface areas and richer active sites,enabling simultaneous high adsorption capability and strong catalytic properties.The synergistic effect of the“adsorption-catalysis”sites accelerates the adsorptiondiffusion-conversion process of Li PSs,ultimately achieving a long-lasting Li-S battery.Herein,the latest progress and performance of bimetallic materials in cathodes,separators,and interlayers of Li-S batteries are systematically reviewed.Firstly,the principles and challenges of Li-S batteries are briefly analyzed.Then,various mechanisms for suppressing“shuttle effects”of Li PSs are emphasized at the microscale.Subsequently,the performance parameters of various bimetallic materials are comprehensively summarized,and some improvement strategies are proposed based on these findings.Finally,the future prospects of bimetallic materials are discussed,with the hope of providing profound insights for the rational design and manufacturing of high-performance bimetallic materials for LSBs.

Deformation Characteristics and Mechanical Properties of Ti/Al Bimetallic Composite Materials Fabricated by Wire Plus Arc Additive Manufacturing

We focused on Ti/Al composite materials fabricated by wire and arc addictive manufacturing,and the microstructure and interface characteristics of them before and after hot compression deformation were compared.After compression deformation,allαstructures of titanium were compacted with the emergence of Widmanstatten structures.Coarsened coloniesαof titanium were elongated and waved along the original growth direction,resulting in anisotropy of grains.Pores and Ti/Al intermetallic compounds of aluminum are significantly decreased after hot compression.Meanwhile,a good bonding interface between titanium and aluminum is obtained after hot compression,and the element diffusion is more intense.In addition,the mechanical properties and fracture behaviors of Ti/Al composite material with different clad ratio that is defined as the ratio of the thickness of titanium to that of the Ti/Al composite material are investigated by uniaxial tensile test.The experimental results show that the ultimate tensile strength of Ti/Al composite material is between that of single deposited titanium and aluminum,while the elongation of Ti/Al composite material with low clad ratio is lower than that of single aluminum due to the metallurgical reaction.As the clad ratio increases,the two component layers are harder to separate during deformation,which is resulted from the decrease of the inward contraction stress of three-dimensional stress caused by necking of aluminum.This work may promote the engineering application of Ti/Al bimetallic structures.

High strength bimetallic composite material fabricated by electroslag casting and characteristics of its composite interface

Bimetallic composite material of bainitic steel and PD3 steel was produced with electroslag casting process, and element distribution of its composite interface was investigated by theoretical calculation and energy dispersive spectrometer(EDS). Results show that the tensile strength(1,450 MPa), hardness(HRC 41-47) and impact toughness(94.7J·cm^(-2)) of bainitic steel were comparatively high, while its elongation was slightly low(4.0%). Tensile strength(1,100 MPa), hardness(>HRC 31) and elongation(7.72%) of the interface were also relatively high, but its impact toughness was low at 20.4 J·cm^(-2). Results of theoretical calculation of the element distribution in the interface region were basically consistent with that of EDS. Therefore, electroslag casting is a practical process to produce bimetallic composite material of bainitic steel and PD3 steel, and theoretical calculation also is a feasible method to study element distribution of their interface.

Study on Solid Self-Lubricating Material for Plasma Facing Components in EAST

In this study, the friction performance of self-lubricating material with the counterpart steel ball-plate rubbing was investigated in vacuum conditions and the thermal distortion of the heat sink sample was tested. The analysis and test results show that the self-lubricating ma- terial has excellent anti-friction properties in high vacuum condition and can decrease the thermal stress and avoid damage to the PFCs during physical experiments.

Tribological Properties of Self-lubricating Laminated Ceramic Materials

In order to improve the tribological properties of ceramic composites, Al2O3/TiC-Al2O3/ TiC/CaF2 self-lubricating laminated ceramic composites were prepared by vacuum hot pressing sintering. Experiments were conducted to get mechanical properties and the friction and wear properties were also measured with friction and wear tester. The worn surfaces were observed by scanning electron microscope （SEM） and energy dispersion spectrum （EDS）. The wear resistance properties and the self-lubricating effect of ceramic composites were analyzed. Results show that the Al2O3/TiC-Al2O3/TiC/CaF2 self-lubricating laminated ceramic composites layers are well-defined with a higher bonding strength and the mechanical performances are uniform enough to overcome the anisotropy of weak laminated ceramic composites. In addition, the fracture toughness of Al2O3/TiC layers is also improved. Its friction coefficient and wear rates decrease with the increase of rotation speed and load. Al2O3/TiC-Al2O3/TiC/CaF2 self-lubricating laminated ceramic composites have good wear resistance because of the tribofilm formed by the CaF2 solid lubricants. The wear mechanisms of Al2O3/TiC/ CaF2 layers are abrasive wear and Al2O3/TiC layers are adhesive wear.

Effects of copper-coated MoS_(2) on friction performance of bronze-graphite-MoS_(2) self-lubricating materials

Two kinds of bronze-graphite-MoS_(2) self-lubricating materials with copper-coated MoS_(2) and uncoated MoS_(2) were prepared by powder metallurgy.Friction and wear experiments were carried out under 4 N and 10 N loads respectively,and the effects of copper-coated MoS_(2) on the friction performances of the materials were studied.Results showed that the way of copper-coated on the surface of MoS_(2) could reinforce the bonding between MoS_(2) and matrix,and inhibited the formation of MoO_(2).Moreover,both materials formed a MoS_(2) lubricating film on the surface during the friction process.While the lubricating film formed after copper coating on MoS_(2) was thicker and had uneven morphology,it was more conducive to improving the friction performance of the material.Compared with conventional materials,the wear rate of copper-coated materials was reduced by one order of magnitude,and the friction coefficient was also reduced by 22.44% and 22.53%,respectively,when sliding under 4 N and 10 N loads.It shows that copper-coated MoS_(2)can improve friction properties of bronze-graphite-MoS_(2)self-lubricating materials furtherly.

Phase separation-hydrogen etching-derived Cu-decorated Cu-Mn bimetallic oxides with oxygen vacancies boosting superior sodium-ion storage kinetics

Understanding the crystal phase evolution of bimetallic oxide anodes is the main concern to profoundly reveal the conversion reaction kinetics and sodium-ion storage mechanisms.Herein,an integrated selfsupporting anode of the Cu-decorated Cu-Mn bimetallic oxides with oxygen vacancies(Ov-BMO-Cu)are in-situ generated by phase separation and hydrogen etching using nanoporous Cu-Mn alloy as selfsacrificial templates.On this basis,we have elucidated the relationship between the phase evolution,oxygen vacancies and sodium-ion storage mechanisms,further demonstrating the evolution of oxygen vacancies and the inhibition effect of manganese oxides as an“anchor”on grain aggregation of copper oxides.The kinetic analyses confirm that the expanded lattice space and increased oxygen vacancies of cycled Ov-BMO-Cu synergistically guarantee effective sodium-ion diffusion and storage mechanisms.Therefore,the Ov-BMO-Cu electrode exhibits higher reversible capacities of 4.04 mA h cm^(-2)at 0.2 mA cm^(-2)after 100 cycles and 2.20 m A h cm^(-2)at 1.0 mA cm^(-2)after 500 cycles.Besides,the presodiated Ov-BMO-Cu anode delivers a considerable reversible capacity of 0.79 m A h cm^(-2)at 1.0 mA cm^(-2)after 60 cycles in full cells with Na_(3)V_(2)(PO_(4))_(3)cathode,confirming its outstanding practicality.Thus,this work is expected to provide enlightenment for designing high-capacity bimetallic oxide anodes.

Wear behavior of SiC/PyC composite materials prepared by electromagnetic-field-assisted CVI

Silicon carbide/pyrolytic carbon (SiC/PyC) composite materials with excellent performance of self-lubrication and wear resistance were prepared on SiC substrates by electromagnetic-field-assisted chemical vapor infiltration (CVI). The composition and microstructure of the SiC/PyC materials were investigated in detail by XRD, SEM and EDS, etc. The effects of the deposition temperature on the section features and wear resistance of the SiC/PyC were studied. The results show that the PyC layers were deposited onto SiC substrates spontaneously at a lower deposition temperature. The SiC substrates deposited with PyC can significantly reduce the wear rate of the self-dual composite materials under dry sliding condition. The wear tests suggest that the SiC/PyC composite materials own a better wear resistance property when the deposition temperature is 800 °C, and the wear rate is about 64.6% of that without the deposition of PyC.

Boosting the hydrogen storage performance of magnesium hydride with metal organic framework-derived Cobalt@Nickel oxide bimetallic catalyst

In this study,a MOF-derived bimetallic Co@NiO catalyst was synthesized and doped into MgH_(2)to improve the hydrogen desorption and resorption kinetics.The Co@NiO catalyst decreased the onset dehydrogenation temperature of MgH_(2)by 160℃,compared with un-doped MgH_(2).The MgH^(2+)9%(mass)Co@NiO composite released 6.6%(mass)hydrogen in 350 s at 315℃and uptook 5.4%(mass)hydrogen in500 s at 165℃,showing greatly accelerated de/rehydrogenation rates.Besides,the desorption activation energy of MgH^(2+)9%(mass)Co@NiO was decreased to(93.8±8.4)kJ·mol^(-1).Noteworthy,symbiotic Mg_(2)NiH_(4)/Mg_(2)CoH_(5)clusters were in-situ formed from bimetallic precursors and inlaid on MgH_(2)surface,which are considered as"multi-step hydrogen pumps",and provides surface pathways for hydrogen absorption.Meanwhile,the introduced Mg_(2)NiH_(4)/Mg_(2)CoH_(5)interfaces could provide numerous low energy barrier H diffusion channels,therefore accelerating the hydrogen release and uptake.This research proposes new insights to design high-efficiency bimetallic catalyst for MgH_(2)hydrogen storage.

双金属MOFs碳化材料的结构对锂硫电池正极性能的影响

利用硝酸钴和铁氰化钾在水溶液中沉淀反应以及ZIF-8在水溶液中的部分分解,分别制备了2种组成相近但结构不同的双金属有机框架前驱体Co-Fe precursor和ZCF precursor。经过多巴胺包覆,对2种产品在氩气气氛下退火获得碳化产物。将碳化产物与纳米硫粉混合得到的碳/硫复合材料(E-CoFeCN@C/S、E-ZCF@C/S)分别作为正极,组装扣式锂硫电池并测试电化学性能。利用X射线衍射仪、扫描电子显微镜、透射电子显微镜、热重分析仪进行形貌和结构分析。在组成相似的情况下,核壳结构碳载体(E-CoFeCN@C)与发散式结构碳载体(E-ZCF@C)对锂硫电池性能的影响呈现出“此消彼长”的特点:E-ZCF@C/S在循环伏安测试中表现出更小的极化以及更强的电流响应,在电化学阻抗测试中表现出更低的电荷转移阻抗,表明该材料有利于促进正极电荷传递过程,即加快电极反应动力学。E-ZCF@C/S在0.2C倍率下放电初始比容量为1211.3mAh/g,在2C倍率下放电初始比容量为794mAh/g,均优于E-CoFeCN@C/S。而核壳结构的优势主要体现在容量衰减方面,E-CoFeCN@C/S在0.2C倍率下经过100次循环后平均衰减率为0.074%(E-ZCF@C/S为0.26%),在2C倍率下循环300次后平均衰减率为0.047%(E-ZCF@C/S为0.13%),说明核壳结构对活性物质的锚固作用明显而对电荷转移不利。

低合金钢/不锈钢双金属复合结构件界面行为研究进展

低合金钢/不锈钢双金属复合结构件兼具优异的耐蚀性能和较低的生产成本,被应用于含CO2、H2S油田地面集输管道等领域,但由于低合金钢与不锈钢热物性能存在差异,在冶金结合过程中,双金属界面附近会存在较大的残余应力,在残余应力与腐蚀介质的双重作用下,双金属复合结构件界面附近容易发生应力腐蚀开裂。简要介绍了低合金钢/不锈钢双金属复合结构件的制造技术,对双金属连接界面附近不锈钢侧合金元素的扩散、应力腐蚀开裂的研究现状和关键技术进行了总结,分析了低合金钢/不锈钢双金属结构件过渡材料的选用原则,并提出了过渡材料或焊接材料的选用建议,为双金属复合结构件的研究和应用提供参考。

Co_(0.5)Cu_(0.5)/CNR催化剂制备及其氨硼烷水解制氢性能研究

以硝酸钴和硝酸铜制备溶液A,苯二甲酸(PTA)和N,N-二甲基甲酰胺(DMF)制备溶液B,两种溶液通过溶剂热法制备Co/Cu拉瓦希尔骨架系列材料(Co/Cu-MIL前驱体),进一步直接碳化前驱体制备出MOFs衍生物,即双金属碳纳米棒(CoxCu_(1-x)/CNR)催化剂。通过SEM、TEM、XRD、XPS等表征手段探究其形貌和组成。结果表明,Co/Cu-MIL经过高温焙烧后成功得到CoxCu_(1-x)/CNR,当x=0.5、溶剂热温度为120℃、焙烧温度为650℃时得到的催化剂催化活性最优,Co_(0.5)Cu_(0.5)/CNR催化剂催化氨硼烷(AB)水解制氢的TOF值为2718.21 h^(-1),反应的活化能为51.64 kJ/mol,且催化剂的循环稳定性较好,在循环10次后催化活性虽然有所下降,但对AB仍然保持100%的转化率。

增材制造铜/钢双金属材料研究进展

铜/钢双金属材料具有力学强度高、物理化学性能优良等优势,在交通运输、电力能源和建筑工业等领域应用前景广阔。然而,传统熔铸工艺在制造铜/钢双金属材料时,容易在铜/钢界面处产生偏析现象,在一定程度上限制了铜/钢双金属材料的发展。与传统工艺相比,增材制造技术不仅能实现复杂加工零件的快速制造,而且在成形过程中较短的保温时间能缓和或消除异种金属材料界面产生的冶金缺陷,进而增强铜/钢双金属材料的力学性能。由于双金属材料是近年来的研究热点,有关增材制造铜/钢双金属材料的综述性文章较少,故综述了近年来激光、电子束及电弧增材制造技术制造铜/钢双金属材料的研究发展现状,分析了各技术的优缺点,并从制备方法、工艺参数及界面合金元素等角度,分析了影响材料界面组织性能变化的关键因素。发现在增材制造铜/钢双金属材料方面,目前激光增材制造技术主要应用于精度要求较高的小尺寸零部件,电子束增材制造技术适用于某些具有特殊性能的合金,如钛合金,而电弧增材制造技术适用于精度要求较低的大型复杂零部件。在铜/钢双金属材料增材制造过程中,界面处易形成显微组织分布不均匀、界面晶粒尺寸差异较大等现象,导致界面处产生应力集中,从而造成材料断裂失效。为解决上述难题,学者们已深入研究第二相形成机理,并采用优化界面处Cu-Fe比例和控制脆相金属间化合物等方式提高铜/钢双金属材料的性能。最后,对目前增材制造铜/钢双金属材料的研究发展现状进行了总结与展望,未来在冶金学和热力学方向上对铜/钢双金属材料仍需进行系统性理论研究,对双金属材料而言需要建立相关模拟数据库,以期为相关从业人员提供精细化指导建议。新型增材制造技术或复合增材制造技术的开发与应用都将成为未来增材制造铜/钢双金属材料研究的重点发展方向。

HB400/HG70双金属工程机械钢热轧结合行为模拟研究

目的研究HB400/HG70双金属热轧过程中轧制温度、压下率和轧辊转速对应力、应变及温度分布的影响规律。方法利用ABAQUS有限元数值模拟软件,建立了HB400耐磨钢/HG70焊接钢双金属热轧有限元模型。结果当压下率从50%增加至60%时,HB400与HG70两侧等效应变差值增大,已结合的部位由于变形量加大和应力集中导致结合失效。当压下率为50%时,结合区域等效应变为0.77~0.87,两侧的平均等效应变差值为0.0047且最大值为0.01。轧制速度过快导致双金属未完全结合就离开了轧制区域,降低轧制速度可以使垂直轧制方向的应力分布更均匀,当轧制速度为0.6 rad/s时,HB400与HG70两侧等效应变没有明显差别。温度升高可以提高HB400与HG70两侧的变形均匀性。随着压下率的增加,复合板与轧辊的传热效率增强。复合板的温度下降更加明显。结论HB400与HG70双金属复合板的轧制协调性较好,无明显翘曲。热轧后双金属外侧应力大于结合区域应力;提高轧制温度、压下率和降低轧辊转速,能使垂直轧制方向的应力分布更均匀。最佳的热轧条件为温度1200℃、压下率50%、轧制速度0.6rad/s。

生物炭负载水滑石复合材料的制备及其对Cr(Ⅵ)的吸附性能

以甘蔗渣纤维为原材料,采用碳化法和共沉淀法制备改性生物炭类吸附材料BC@MnAl-LDHs,通过静态试验研究BC@MnAl-LDHs的投加量(0.5、1.0、2.0、3.0、4.0、5.0、6.0 g/L)、溶液初始pH(3、4、5、6、7、8)、污染物初始质量浓度(5、10、20、40、60、80、100 mg/L)、温度(298、303、308、313 K)和吸附反应时间(2、15、60、120、180、240、480、600、720 min)对其吸附Cr(Ⅵ)的影响,并运用X射线衍射(XRD)、扫描电子显微镜(SEM)、傅里叶变换红外光谱(FTIR)、比表面积及孔隙度分析(BET)对吸附Cr(Ⅵ)前后的BC@MnAl-LDHs进行表征与分析,同时分析其吸附机理。结果表明:当BC@MnAl-LDHs投加量为2.0 g/L、Cr(Ⅵ)初始质量浓度为10 mg/L、pH为3时,Cr(Ⅵ)去除率可达95%以上,改性提高了甘蔗渣活性炭对Cr(Ⅵ)的去除效率;BC@MnAl-LDHs对Cr(Ⅵ)的吸附等温线更符合Freundlich吸附模型,在313 K下,用Langmuir模型拟合得到其饱和吸附量为56.42 mg/g,符合拟二级动力学模型,吸附过程为多分子层、自发、吸热的化学吸附过程;BC@MnAl-LDHs含有丰富的含氧官能团,有助于其对Cr(Ⅵ)的去除,BC@MnAl-LDHs对Cr(Ⅵ)的吸附作用主要包括氧化还原、离子交换和静电吸附。

CoV-LDH@NiCo-LDH材料制备及赝电容储能性能研究

钴钒层状双金属氢氧化物(CoV-LDH)具有丰富的电化学活性位点,但仍然存在着低价钒源昂贵、制备困难、钒溶解等问题。研究采用电化学阴极还原法制备三维多孔状CoV-LDH电极材料,为提高CoV-LDH在碱性电解液中的稳定性,通过二次电沉积构建核壳结构CoV-LDH@NiCo-LDH复合材料,具有纳米球包覆纳米片微观形貌,且Ni、Co、V三元素分布均匀,增加了材料的活性位点与电解液的接触面积,降低了材料界面阻抗,赝电容储能性能有较大的提升。在1A/g电流密度下,CoV-LDH@NiCo-LDH比电容可达到995.8 F/g,远优于CoV-LDH的比电容(575.2 F/g),比电容显著提高了73.1%,具有优异的倍率性能,在50 mV/s扫速下,赝电容占比85%。在经过2000次循环后,循环稳定性可达85%。分析NiCo-LDH@CoV-LDH电极材料的反应动力学及能量储存机制,其不仅表现出电池型法拉第行为,而且表现出电容特性。将正极材料与活性炭(AC)负极组装形成CoV-LDH@NiCo-LDH∥AC非对称超级电容器,在1 A/g的电流密度下,比电容可达222.2 F/g;功率密度为222.2 W/kg时的能量密度为30.86 Wh/kg,该工作为钒基双金属氢氧化物材料的制备与储能应用奠定基础。

铜铝双金属材料对硝基苯废水的还原降解研究

以废旧铝箔为原料,采用化学镀铜的方式制备了铜铝双金属材料(Cu@Al^(0))并应用于硝基苯废水的还原降解。采用X射线衍射(XRD)、扫描电子显微镜(SEM)等手段对制备的材料进行表征,系统考察了镀铜率、初始pH、Cu@Al^(0)投加量、硝基苯初始浓度对硝基苯降解效果的影响,最后借助紫外可见吸收光谱(UV-Vis)和气相色谱(GC)进一步揭示了Cu@Al^(0)对硝基苯的还原降解机理。结果表明,金属铜可成功负载在铝箔表面,当铜负载率为3.43%,初始pH=3,Cu@Al^(0)投加量为0.50 g,硝基苯初始质量浓度为100 mg/L,反应时间为20 min时硝基苯的降解率可达88.4%,且Cu@Al^(0)具有良好的循环利用性能。Cu@Al^(0)对硝基苯的降解是从亚硝基苯到羟基苯胺再到苯胺的逐步还原过程,初始pH过高会影响中间产物亚硝苯进一步还原成最终产物苯胺。

Highly uniform Co-Cu bimetallic sulfides for rechargeable alkaline aqueous zinc batteries

Rechargeable alkaline aqueous zinc batteries(RAZBs)have attracted increasing attention.However,most RAZBs are hindered by the limited availability of cathode materials.The practical electrochemical performance of most cathode materials is lower than the theoretical value due to their poor electrical conductivity and low utilization capacity.In this work,we develop a facile hydrothermal procedure to prepare highly uniform bimetallic sulfides as novel cathode materials for RAZBs.Copper-cobalt binary metallic oxides materials possess higher conductivity and larger capacity compared with their mono-metal oxides compounds due to bimetallic synergistic effects and multiple oxidation states.Furthermore,bimetallic sulfide compounds have smaller bond energy and longer bond length than their oxides,leading to less structural damage,faster kinetics of electrochemical reactions,and better stability.The as-prepared Co-Cu bimetallic sulfides show enhanced electrochemical performance due to various valences of Co and Cu as well as the existence of S.As a result,aqueous Zn/CuCo_(2)S_(4) battery shows a high specific capacity of 117.4 mAh/g at 4 A/g and a good cycle life of over 8000 cycles.Based on PANa hydrogel electrolytes,a flexible Zn/CuCo_(2)S_(4) battery demonstrates excellent cycling stability.This battery can also meet the requirements of electronic devices with different shapes and performs well in extreme environments,such as freezing,drilling,and hammering.This work opens new avenues to obtain high-rate and long-life cathode materials for RAZBs by utilizing the synergistic effects of bimetallic sulfides and provides a new platform for flexible energy storage devices.

Significantly enhanced ion-migration and sodium-storage capability derived by strongly coupled dual interfacial engineering in heterogeneous bimetallic sulfides with densified carbon matrix

The development of highly efficient sodium-ion batteries depends critically on the successful exploitation of advanced anode hosts that is capable of overcoming sluggish reaction kinetics while also withstanding severe structural deformation triggered by the large radius of Na^(+)-insertion.Herein,a hierarchically hybrid material with hetero-Co_(3)S_(4)/NiS hollow nanosphere packaged into a densified N-doped carbonmatrix(Co_(3)S_(4)/NiS@N-C)was designed and fabricated utilizing CoNi-glycerate as the self-sacrifice template,making the utmost of the synergistic effect of hetero-Co_(3)S_(4)/NiS with strong electric field and rich reaction active-sites together with the densified outer-carbon scaffolds with remarkable electronic conductivity and robust mechanical toughness.As anticipated,as-fabricated Co_(3)S_(4)/NiS@N-C anode affords remarkable specific capacity,prolonged cycle lifespan up to 2400 cycles with an only 0.05%fading each cycle at 20.0 A g^(−1),and excellent rate feature(354.9 mAh g^(−1)at 30.0 A g^(−1)),one of the best performances for most existing Co_(3)S_(4)/NiS-based anodes.Ex situ structural characterizations in tandem with theoretical analysis demonstrate the reversible insertion-conversion mechanism of initially proceeding with Na^(+)de-/intercalation and superior heterogeneous interfacial reaction behavior with strong Na^(+)-adsorption ability.Further,sodium-ion full cell and hybrid capacitor based on Co_(3)S_(4)/NiS@N-C anode exhibit impressive electrochemical characteristics on cycling performance and rate capability,showcasing its outstanding feasibility toward practical use.

一种宽带高灵敏水声换能器的有限元分析

针对声呐系统中微型目标探测与水下定位等应用,设计了一种宽带高灵敏度水声换能器。采用双金属板压电陶瓷柱阵列材料作为换能器敏感元件,以空气代替聚合物,并在压电陶瓷柱阵列上下表面粘接金属板,改善了材料的有效机电耦合系数,提高了换能器灵敏度;通过不同厚度敏感元件嵌套式叠加,拓展了换能器工作带宽。理论分析了双金属板压电陶瓷柱阵列材料的谐振频率;利用有限元仿真确定了敏感元件的尺寸参数与材料选择,并对由该结构敏感元件组成的换能器进行了水中仿真测试。结果表明,换能器工作带宽达到约80 kHz,最大发送电压响应为188.6 dB,-3 dB带宽约为74 kHz,最大接收灵敏度为-173.9 dB。与同尺寸的纯压电陶瓷相比,该换能器的接收灵敏度和带宽都得到有效改善。