Apically guiding electron/mass transfer reaction induced by Ag/FeN_(x)Mott-Schottky effect within a hollow star reactor toward high performance zinc-air batteries

The disparity in the transfer of carriers(electrons/mass)during the reaction in zinc-air batteries(ZABs)results in sluggish kinetics of the oxygen reduction reaction(ORR)and oxygen evolution reaction(OER),along with elevated overpotentials,thereby imposing additional constraints on its utilization.Therefore,the pre-design and target-development of inexpensive,high-performance,and long-term stable bifunctional catalysts are urgently needed.In this work,an apically guiding dual-functional electrocatalyst(Ag-FeN_(x)-N-C)was prepared,in which a hierarchical porous nitrogen-doped carbon with three-dimensional(3D)hollow star-shaped structure is used as a substrate and high-conductivity Ag nanoparticles are coupled with iron nitride(FeN_(x))nanoparticles.Theoretical calculations indicate that the Mott-Schottky heterojunction as an inherent electric field comes from the two-phase bound of Ag and FeN_(x),of which electron accumulation in the FeN_(x)phase region and electron depletion in the Ag phase region promote orientated-guiding charge migration.The effective modulation of local electronic structures felicitously reforms the d-band electron-group distribution,and intellectually tunes the masstransfer reaction energy barriers for both ORR/OER.Additionally,the hollow star-s haped hierarchical porous structure provides an apical region for fast mass transfer.Experimental results show that the halfwave potential for ORR is 0.914 V,and the overpotential for OER is only 327 mV at 10 mA cm^(-2).A rechargeable ZAB with Ag-FeN_(x)-N-C as the air cathode demonstrates long-term cycling performance exceeding 1500 cycles(500 h),with a power density of 180 mW cm^(-2).Moreover,when employing AgFeN_(x)-N-C as the air cathode,flexible ZABs demonstrate a notable open-circuit voltage of 1.42 V and achieve a maximum power density of 65.6 mW cm^(-2).Ag-FeN_(x)-N-C shows guiding electron/mass transfer route and apical reaction microenvironment for the electrocatalyst architecture in the exploration prospects of ZABs.

基于局部高盐界面润湿策略构筑的固态金属锂软包电池

固态金属锂电池因其优异的安全性和高的理论能量密度被认为是最具前景的下一代储能电池体系之一。随着以硫化物为代表的高离子导率电解质被逐渐开发,金属锂与固态电解质界面成为限制固态电池应用的主要瓶颈。金属锂/电解质的固固界面存在着界面接触差、界面电荷传输阻力高等问题。本文以固态金属锂软包电池为研究对象,通过由1,1,2,2-四氟乙基-2,2,3,3-四氟丙基醚、乙二醇二甲醚与双三氟磺酰亚胺锂组成的局部高盐液态电解液(HFE-DME LiTFSI)对金属锂/固态电解质界面进行润湿,增加金属锂与固态电解质之间的离子接触,降低离子传输阻力,从而提高锂离子在界面的传输能力。在30 mm×30 mm Li|Li4Ti5O12(LTO)固态软包电池中,通过3.0μL·cm^(−2) HFE-DME LiTFSI局部高盐液态电解液润湿金属锂与固态电解质界面,软包电池的界面电阻从4366Ω·cm^(−2)降低到了64Ω·cm^(−2)。在0.1C与0.5C倍率下,LTO的放电比容量分别达到107与96 mAh·g^(−1)。同时,Li-S固态软包电池在0.01C及0.02C下,比容量也达到了1100与932 mAh·g^(−1)。

Iron(Fe,Ni,Co)-based transition metal compounds for lithium-sulfur batteries:Mechanism,progress and prospects

Lithium-sulfur batteries(LSBs)have a high theoretical capacity,which is considered as one of the most promising high-energy-density secondary batteries due to the double electrons reaction of sulfur.However,the shuttle effects of lithium polysulfides(Li PSs)and sluggish redox kinetics lead to their materials capacity loss and cycle stability deterioration,which restrains LSBs commercialization.Metallic compounds as additions can improve the electrochemical performance of the Li-S system,through the trap of Li PSs and accelerate the conversion of the soluble Li PSs.Among of them,the iron group elements(Fe,Ni,Co)-based compounds are the promising materials for the LSBs,due to their unique outer electronic structure and its tunable properties,low cost,abundant in the earth,environmental benignity,controllable and scalable prepared,and so on.In this review,we have made a summary for iron-based compounds to capture Li PSs according to lithium bond,sulfur bond and magnetic force.The type of iron-based compound including oxides,sulfides,nitrides,phosphides,carbides,and so on,and we have investigated the electrocatalytic mechanism of these materials.Besides,some improvement strategies are proposed,such as the engineering of the special micro/nanostructure,defect concentrations,band structures,and heterostructures.We hope to shed an in-depth light on the rationally design and fabrication of robust,commercial and stable materials for high-performance LSBs.

Directional assist (0 1 0) plane growth in LiMnPO_(4) prepared by solvothermal method with polyols to enhance electrochemical performance

Phosphate material LiMnPO4 is popular for its high energy density(697 W·h·kg^(-1))and safety.When LiMnPO_(4) crystal grows,the potential barrier along b and c axis is strong,which makes the crystal grow along b axis to form a one-dimensional chain structure.However,the main migration channel of lithium ions in olivine structure is plane(010).By shortening the growth in the direction of b axis and enhancing the diffusion along the directions of a and c,two-dimensional nanosheets that are more conducive to the migration of lithium ions are formed.The dosage of polyols is the key factor guiding the dispersion of the crystals to the(010)plane.X-ray diffraction(XRD),Scanning electron microscopy(SEM),transmission electron microscopy(TEM)and other means are used to characterize the samples.After experiments,we found that when the ratio of polyol/water was 2:1,the morphology of the synthesized sample was 20–30 nm thick nanosheets,which had the best electrochemical performance.At 0.1C,the discharge specific capacity reaches 148.9 mA·h·g^(-1),still reaches 144.3 mA·h·g^(-1) at the 50th cycle.and there is still 112.5 mA·h·g^(-1) under high rate(5C).This is thanks to the good dispersion of the material in the direction of the crystal plane(010).This can solve the problem of low conductivity and ionic mobility of phosphate materials.

Designing Electrochemical Nanoreactors to Accelerate Li_(2)S_(1/2) Three-Dimensional Growth Process and Generating More Li_(2)S for Advanced Li–S Batteries

With advantages of low costs and high energy density,Li–S batteries are considered as one of the most promising energy storage devices.However,Li_(2)S_(2) with a high dissociation energy and insulative properties is hard to convert into Li_(2)S,resulting in underutilization of sulfur capacity.Herein,Co-Mo_(2)C@C yolk–shell spheres as nanoreactors were designed to confront this challenge rationally.The Co-Mo_(2)C@C-induced Li_(2)S_(1/2) nucleation and growth in the three-dimensional process and the cathode produced more Li_(2)S after full discharge.Experimental studies and theoretical calculations reveal that the conversion barrier from Li_(2)S_(2) into Li_(2)S was lowered while the diffusion of lithium ions and electron transfer accelerated when using the Co-Mo_(2)C@C catalyst.Based on the above advantages,the Co-Mo_(2)C@C/S cathode exhibits a high reversible capacity and excellent cyclic stability,such as an initial specific capacity of 1200 mAh g^(−1) at 0.1 C with 709 mAh g^(−1) at 1.0 C after 1000 cycles with a low capacity fading rate of 0.04%per cycle.Even at high densities of 3.0 C and 5.0 C,the specific capacities are 647.6 and 557.7 mAh g^(−1) after 400 cycles,respectively.Impressively,it also shows ca.770 and 900 mAh g^(−1) at 0.2 C after 50 cycles with high sulfur loadings of 4.2 and 5.1 mg cm−2,respectively.The present work may provide new insights into the design of nanoreactors to promote Li_(2)S_(1/2) growth in a three-dimensional process and accelerate conversion from solid Li_(2)S_(2) to solid Li_(2)S in high performance Li–S batteries.

Renewable wood-derived hierarchical porous,N-doped carbon sheet as a robust self-supporting cathodic electrode for zinc-air batteries

Heteroatom doped porous carbon materials have emerged as essential cathode material for metal-air battery systems in the context of soaring demands for clean energy conversion and storage.Herein,a three-dimensional nitrogen-doped carbon self-supported electrode(TNCSE)is fabricated through thermal treatment and acid activation of raw wood.The resulting TNCSE retains the hierarchical porous architecture of parent raw lumber and holds substantial defect sites and doped N sites in the carbon skeleton.Assembled as a cathode in the rechargeable zinc-air battery,the TNCSE exhibits a superior peak power density of 134.02 m W/cm^(2)and an energy density of 835.92 m Ah/g,significantly exceeding the ones reference commercial 20%Pt/C does.More strikingly,a limited performance decay of 1.47%after an ultra long-period(500 h)cycle is also achieved on the TNCSE.This work could offer a green and cost-save approach for rationally converting biomass into a robust self-supporting cathode material for a rechargeable zinc-air battery.

高安全、高比能固态锂硫电池电解质

锂硫电池具有理论能量密度高、成本低廉和环境友好等优点,是最有前途的下一代高比能二次电池系统之一。当前,基于有机电解液的液态锂硫电池存在多硫化锂穿梭效应、电解液易燃以及锂枝晶等问题,致使电池的库仑效率低、循环性能差,且存在严重的安全隐患。采用固态电解质(如凝胶聚合物、固态聚合物、陶瓷、复合电解质等)替代有机电解液是解决上述问题的有效途径。本文总结了近年来固态锂硫电池电解质的研究现状,评述了各类固态电解质的优缺点及改性策略,重点介绍了陶瓷固态电解质的研究进展。最后,对固态锂硫电池的未来发展趋势进行预测与展望。

三元镍钴锰正极材料的制备及改性

三元镍钴锰正极材料是一类非常重要的正极材料,具有性能优于钴酸锂而成本远远低于钴酸锂、能量密度远远高于磷酸铁锂等重要优点,正在逐渐成为汽车动力电池的主流正极材料。但是,三元镍钴锰正极材料也存在循环稳定性不足、大电流密度放电性能不佳等问题。围绕解决这些问题并进一步提升三元镍钴锰正极材料的性能,近年来国内外在材料制备技术以及改性技术方面开展了大量的研究工作,取得了若干令人瞩目的研究成果。本文从材料制备方法、包覆修饰和掺杂改性三个方面,介绍了三元镍钴锰正极材料制备技术及改性技术的研究进展,在此基础上,对三元镍钴锰正极材料的未来发展方向作出展望。

Engineering the electronic and strained interface for high activity of PdMcore@Ptmonolayer electrocatalysts for oxygen reduction reaction

Alloyed nanoparticles with core-shell structures provide a favorable model to modulate interfacial interaction and surface structures at the atomic level,which is important for designing electrocatalysts with high activity and durability.Herein,core-shell structured Pd3M@Pt/C nanoparticles with binary PdM alloy cores(M=Fe,Ni,and Co)and a monolayer Pt shell were successfully synthesized with diverse interfaces.Among these,Pd3Fe@Pt/C exhibited the best oxygen reduction reaction catalytic performance,roughly 5.4 times more than that of the commercial Pt/C catalyst used as reference.The significantly enhanced activity is attributed to the combined effects of strain engineering,interfacial electron transfer,and improved Pt utilization.Density functional theory simulations and extended X-ray absorption fine structure analysis revealed that engineering the alloy core with moderate lattice mismatch and alloy composition(Pd3Fe)optimizes the surface oxygen adsorption energy,thereby rendering excellent electrocatalytic activity.Future researches may use this study as a guide on the construction of highly effective core-shell electrocatalysts for various energy conversions and other applications.

Inhibition of lithium dendrites and dead lithium by an ionic liquid additive toward safe and stable lithium metal anodes

The uncontrolled growth of lithium dendrites and accumulation of"dead lithium"upon cycling are among the main obstacles that hinder the widespread application of lithium metal anodes.Herein,an ionic liquid(IL)consisting of 1-methyl-1-propylpiperidinium cation(Pp_(13)^+) and bis(fluorosulfonyl)imide anion(FSI^(-)),was chosen as the additive in propylene carbonate(PC)-based liquid electrolytes to circumvent the shortcoming of lithium metal anodes.The optimal 1%Pp_(13) FSI acts as the role of electrostatic shielding,lithiophobic effect and participating in the formation of solid electrolyte interface(SEI)layer with enhanced properties.The in-situ optical microscopy records that the addition of IL can effectively inhibit the growth of lithium dendrites and the corrosion of lithium anode.This study delivers an effective modification to optimize electrolytes for stable lithium metal batteries.

“蛋黄蛋壳”结构纳米电极材料设计及在锂/钠离子/锂硫电池中的应用

“蛋黄蛋壳”结构纳米材料,具有易于调控的“蛋黄”、“蛋壳”和“空腔”结构,可视作“纳米反应器”,在催化、储能等领域表现出显著的应用潜力。尤其在电化学能源存储和转换方面,该结构纳米电极具有大的比表面积和独特的核壳结构,在充放电过程中可缓解电极的体积变化,提供快速的离子/电子输运通道,强化中间产物的吸附和提升转换反应效率等,能显著提高电极稳定性、倍率性能和循环性能,是一类较为理想的电极材料。本文针对“蛋黄蛋壳”结构纳米电极在锂/钠离子电池、锂硫电池等新兴二次电池领域的实际应用,总结了具有该结构纳米电极的设计与合成策略,包括:模板法、奥斯特瓦尔德熟化、电化学置换、克肯达尔效应等,评述了各种策略的优缺点以及电极材料的应用进展,最后对该类材料在锂/钠体系及锂硫电池二次电池方面的研究与应用前景进行了展望。