电子堆积工程调控二硒化镍纳米片助力具有快速动力学的钠离子电池（英文）

近年来,钠离子电池电极材料引起了研究者们极大的兴趣.过渡金属硒化物具有高钠离子存储容量,是一种具有前景的钠离子电池负极材料.然而,该类材料较低的电导率以及钠离子脱嵌过程中巨大的体积膨胀,导致了其较差的钠离子电池倍率性能和循环寿命.本工作采用二维的双金属有机框架材料为模板,设计制造了多孔铁掺杂NiSe₂纳米片材料(Fe-NiSe₂@C NSs),该结构具有充分暴露的活性位点,增强的电导率,丰富的空隙和短电子传输路径,易于适应钠离子脱嵌带来的体积膨胀应力,并具有快速的电荷转移动力学.作为钠离子电池负极材料时,Fe-NiSe₂@C NSs表现出高比容量(5 A g^-1电流密度下为302 mA h g^-1)和优异的循环稳定性(5 A g^-1的电流密度下循环1000圈容量保持率为99%).此外,该材料在与Na₃V₂(PO₄)₂O₂F正极材料组成的钠离子全电池...     

TiO2/C复合材料用于钠离子电池负极的性能研究

近年来,TiO₂作为钠离子电池(NIB)负极材料,因其低成本和高稳定性等优势受到广泛关注。但受TiO₂本征电子导电性的固有限制,使得TiO₂作为NIB负极材料导电性较差,导致其容量和倍率等性能不理想。利用海藻酸钠与金属离子自主交联反应的特性,将反应产物在最佳温度下进行简单碳化,制备了具有分级多孔结构的TiO₂/C复合材料,其中TiO₂纳米颗粒均匀地分布在多孔互连的碳基体中,该结构提升了复合材料导电性的同时扩展了钠离子反应的附着位点。将TiO₂/C复合材料用于NIB负极材料,在100 mA·g^-1的电流密度下循环300圈后,电池可逆比容量维持在180.4 mAh·g^-1;进一步,在更高的1000 mA·g^-1电流密度下经过1000次循环后,电池可逆比容量维持在102.3 mAh·g^-1,充分显示出TiO₂/C复合材料作为NIB负极材料的应用潜能。     

Ni-Sn合金量子点镶嵌在多孔纳米碳片复合物的合成及其优异的储钠性能

锡基合金负极材料由于其在储钠过程中拥有高的比容量和低工作电压而备受瞩目,但其在嵌钠/脱钠过程中却易造成原子体积膨胀,从而引起电极材料在储钠时的容量衰减。为了解决这些问题,利用简单的模板法制备出了Ni-Sn合金量子点镶嵌在多孔纳米碳片的复合物(Ni-Sn@PNC),并对比了Ni-Sn的常见两种合金Ni_3Sn_4@PNC、Ni_3Sn_2@PNC和PNC的形貌结构和电化学性能。当它们作为负极材料应用到储钠研究时,Ni_3Sn_4@PNC表现出明高的容量(在100 mA/g的电流密度下进行100圈充放电循环后比容量保持232.7 mAh/g)和出色的循环稳定性(在400 mA/g电流下循环1000圈后具有高达81.6%的容量保持率);PNC拥有较好的倍率性能,而Ni_3Sn_2@PNC却表现出较差的性能。研究结果表明,Ni_3Sn_4作为Ni-Sn合金负极材料的首选,可以利用材料纳米化和多孔纳米碳复合来实现优异的电化学性能。为抑制Sn、Sb和Bi等负极材料在储钠过程中的体积膨胀和性能提升指明了可行的方向。     

钠离子电池中空结构CoSe2/C负极材料的制备及储钠性能研究

过渡金属硒化物具有较高的理论比容量和良好的导电能力, 是钠离子电池潜在的负极材料, 但其在电化学过程中会发生较大体积变化, 循环寿命不佳, 发展受到了限制。为缓解上述问题, 本研究以金属有机框架材料ZIF-67为前驱体, 用单宁酸(Tannic acid, TA)将ZIF-67刻蚀为空心结构, 再通过碳化、硒化制备出以碳为骨架的纳米中空CoSe₂材料(H-CoSe₂/C), 相较于未经刻蚀处理的CoSe₂材料(CoSe₂/C), H-CoSe₂/C表现出更好的储钠性能, 特别是循环稳定性得到显著提高。50 mA·g^-1电流密度下, 经过350次循环, 可逆比容量保持在383.4 mAh·g^-1, 容量保持率为83.6%; 在500 mA·g^-1电流密度下, 经过350次循环后容量保持率仍能达到72.2%。本研究表明, 中空结构能够提供足够的空间以缓解材料在电化学过程中的体积变化, 进而提高电极材料的循环性能。     

具有高循环稳定性的氮硫掺杂多孔碳纳米球钠离子电池负极材料（英文）

开发高性能和低成本的负极材料对于室温钠离子电池(SIBs)的商业化至关重要。本文以葡萄糖为碳源,采用简单的水热法合成了粒径均匀且具备多孔结构的碳纳米球,并通过KOH活化和氮、硫共掺杂对其进行改性。作为钠离子电池的负极材料,该碳纳米球在20 mAg~(-1)的电流密度下表现出高达527 mAhg~(-1)的初始比容量,并且在500 mAg~(-1)的高电流密度下经过1 000次循环之后仍保持了95.2%的初始比容量,其循环稳定性优于大多数近期报道的钠离子电池负极材料。其优异性能来源于KOH活化和异质原子掺杂所带来的丰富的孔结构,较大的层间距和良好的导电性。     

半限域层次孔炭三维锂负极的构筑及性能EI北大核心

金属锂负极是锂电池极具发展潜力的高能二次电池负极材料,但是锂枝晶生长、界面不稳定、循环稳定性差和体积膨胀大等问题限制了锂负极的应用。针对枝晶生长和体积膨胀的问题,本工作通过模板法构筑了一种具有较大比表面积的半限域式层次孔炭(HPC)材料,HPC电极材料的高比表面积可降低局部电流密度,丰富的孔道结构可将锂限制在其内部沉积,从而达到抑制枝晶生长和缓解体积膨胀的目的。Li‖HPC电池在电流密度为1.0 mA·cm^(-2)、沉积电量为1.0 mAh·cm^(-2)条件下可以循环超过250周次,其库仑效率保持在97.6%。采用此负极与磷酸铁锂(LiFePO_(4))正极匹配制备的Li@HPC‖LiFePO_(4)全电池,在0.5 C下循环100周次后的正极放电比容量为93.6 mAh·g^(-1),较相同条件下的Li@Cu‖LiFePO_(4)全电池(60.8 mAh·g^(-1))提升了32.8 mAh·g^(-1)。     

半限域层次孔炭三维锂负极的构筑及性能EI

金属锂负极是锂电池极具发展潜力的高能二次电池负极材料,但是锂枝晶生长、界面不稳定、循环稳定性差和体积膨胀大等问题限制了锂负极的应用。针对枝晶生长和体积膨胀的问题,本工作通过模板法构筑了一种具有较大比表面积的半限域式层次孔炭(HPC)材料,HPC电极材料的高比表面积可降低局部电流密度,丰富的孔道结构可将锂限制在其内部沉积,从而达到抑制枝晶生长和缓解体积膨胀的目的。Li‖HPC电池在电流密度为1.0 mA·cm^(-2)、沉积电量为1.0 mAh·cm^(-2)条件下可以循环超过250周次,其库仑效率保持在97.6%。采用此负极与磷酸铁锂(LiFePO_(4))正极匹配制备的Li@HPC‖LiFePO_(4)全电池,在0.5 C下循环100周次后的正极放电比容量为93.6 mAh·g^(-1),较相同条件下的Li@Cu‖LiFePO_(4)全电池(60.8 mAh·g^(-1))提升了32.8 mAh·g^(-1)。     

半限域层次孔炭三维锂负极的构筑及性能

金属锂负极是锂电池极具发展潜力的高能二次电池负极材料，但是锂枝晶生长、界面不稳定、循环稳定性差和体积膨胀大等问题限制了锂负极的应用。针对枝晶生长和体积膨胀的问题，本工作通过模板法构筑了一种具有较大比表面积的半限域式层次孔炭(HPC)材料，HPC电极材料的高比表面积可降低局部电流密度，丰富的孔道结构可将锂限制在其内部沉积，从而达到抑制枝晶生长和缓解体积膨胀的目的。Li‖HPC电池在电流密度为1.0 mA·cm^-2、沉积电量为1.0 mAh·cm^-2条件下可以循环超过250周次，其库仑效率保持在97.6%。采用此负极与磷酸铁锂(LiFePO₄)正极匹配制备的Li@HPC‖LiFePO₄全电池，在0.5 C下循环100周次后的正极放电比容量为93.6 mAh·g^-1,较相同条件下的Li@Cu‖LiFePO₄全电池(60.8 mAh·g^-1)提升了32.8 mAh·g^-1。     

金属铋纳米颗粒原位修饰碳纳米管促进锂均匀沉积

锂金属具有高理论比容量和低电化学电位,是发展高能量密度电池最有吸引力的负极材料之一。然而,锂金属负极在反复的沉积/剥离过程中,不可避免地会出现不规则的锂枝晶生长,这将严重影响锂金属电池的循环寿命和使用安全性。本研究发展了一种简单温和的策略,在碳纳米管上原位修饰铋纳米颗粒,并涂覆在商业铜箔表面用作锂金属负极的集流体。研究表明,原位修饰的铋纳米颗粒可显著促进锂均匀沉积,抑制锂枝晶生长,从而提高锂金属电池的电化学性能。在电流密度为1 mA·cm^–2的条件下,基于Bi@CNT/Cu集流体的锂铜电池循环300圈后库仑效率可稳定在98%。基于Li@Bi@CNT/Cu负极的对称电池可稳定循环1000 h。基于Bi@CNT/Cu集流体的磷酸铁锂(LFP)全电池也获得了优异的电化学性能,在1C(170m A·g^–1)倍率下可稳定循环700圈。本研究为抑制锂金属负极枝晶生长提供了新的思路。     

二次可充放电电池用硒化锡负极材料的研究现状

硒化锡(SnSe、SnSe_2)因其特殊的层状晶体结构以及较高的导电性,有望成为锂/钠离子电池的负极材料。但是硒化锡负极在充放电过程中体积会反复变化,导致电极结构及表面SEI膜(电极与电解液界面)遭到破坏,使活性材料失去电接触,从而导致循环容量迅速衰减;此外,硒化锡转化反应中间产物Li_2Se/Na_2Se的导电性较差,阻碍了电荷的传输,从而影响了硒化锡电极的电化学反应活性。本文针对硒化锡电极在储锂/钠过程中存在的问题,总结了提升其电化学性能的手段,并概述了国内外学者从构建特殊纳米结构和复合结构等层面上采取的解决办法,揭示了其电化学存储机制以及能够获得的电化学性能。     

赝电容氮掺杂碳包覆Fe1-xS有效促进低温钠存储性能（英文）

近年来,构筑适用于宽温度范围的钠离子电池负极材料越来越引起人们的研究兴趣.Fe1-xS作为一种典型的零带隙材料,由于其低的成本和高的理论比容量,被认为是钠离子电池理想的负极材料.本文以室温合成的Fe金属有机骨架(Fe-MOF)为前驱体,借助硫化处理制备了木耳状氮掺杂碳包覆的Fe1-xS化合物(Fe1-xS@NC).Fe1-xS@NC独特的木耳状结构可以很好地缩短电荷扩散路径,显著提高离子/电子电导率,促进反应的动力学过程.该Fe1-xS@NC电极在8000 mA g^-1的高电流密度下展示了高达510.2 mA h g^-1的理想比容量.即使在0和-25°C的工作环境中,该电极在2000 mA g^-1的电流密度下仍能分别保持387.1和223.4 mA h g^-1的可逆比容量,证实了该电极在严苛温度下的潜在应用.更值得注意的是,由Fe1-xS@NC负极和Na3V2(PO4)2O2F正极组装的全电池在0.3和3.8 V之间同样呈现了出色的倍率容量(在2000 mA g^-1电流密度下的可逆容量为186.8 mA h g^-1)和优异的循环性能(在700 mA g^-1电流密度下、经过100个循环后可维持183.6 mA h g^-1可逆容量).定量动力学分析进一步证实该电极是电容行为为主的电荷存储,这种特质可加速电极电化学动力学反应过程,从而赋予Fe1-xS@NC优异的电化学性能.     

Interface-modulated fabrication of hierarchical yolk–shell Co<Subscript>3</Subscript>O<Subscript>4</Subscript>/C dodecahedrons as stable anodes for lithium and sodium storage

Transition-metal oxides (TMOs) have gradually attracted attention from researchers as anode materials for lithium-ion batteries (LIBs) and sodium-ion batteries (SIBs) because of their high theoretical capacity.However,their poor cycling stability and inferior rate capability resulting from the large volume variation during the lithiation/sodiation process and their low intrinsic electronic conductivity limit their applications.To solve the problems of TMOs,carbon-based metal-oxide composites with complex structures derived from metal-organic frameworks (MOFs) have emerged as promising electrode materials for LIBs and SIBs.In this study,we adopted a facile interface-modulated method to synthesize yolk-shell carbon-based Co3O4 dodecahedrons derived from ZIF-67 zeolitic imidazolate frameworks.This strategy is based on the interface separation between the ZIF-67 core and the carbon-based shell during the pyrolysis process.The unique yolk-shell structure effectively accommodates the volume expansion during lithiation or sodiation,and the carbon matrix improves the electrical conductivity of the electrode.As an anode for LIBs,the yolk-shell Co3O4/C dodecahedrons exhibit a high specific capacity and excellent cycling stability (1,100 mAh·g-1 after 120 cycles at 200 mA·g-1).As an anode for SIBs,the composites exhibit an outstanding rate capability (307 mAh·g-1 at 1,000 mA·g-1 and 269 mAh·g-1 at 2,000 mA·g-1).Detailed electrochemical kinetic analysis indicates that the energy storage for Li+ and Na+ in yolk-shell Co3O4/C dodecahedrons shows a dominant capacitive behavior.This work introduces an effective approach for fabricating carbonbased metal-oxide composites by using MOFs as ideal precursors and as electrode materials to enhance the electrochemical performance of LIBs and SIBs.     

Porous Carbon Nanofibers Encapsulated with Peapod‐Like Hematite Nanoparticles for High‐Rate and Long‐Life Battery Anodes

Fe₂O₃ is regarded as a promising anode material for lithium‐ion batteries (LIBs) and sodium‐ion batteries (SIBs) due to its high specific capacity. The large volume change during discharge and charge processes, however, induces significant cracking of the Fe₂O₃ anodes, leading to rapid fading of the capacity. Herein, a novel peapod‐like nanostructured material, consisting of Fe₂O₃ nanoparticles homogeneously encapsulated in the hollow interior of N‐doped porous carbon nanofibers, as a high‐performance anode material is reported. The distinctive structure not only provides enough voids to accommodate the volume expansion of the pea‐like Fe₂O₃ nanoparticles but also offers a continuous conducting framework for electron transport and accessible nanoporous channels for fast diffusion and transport of Li/Na‐ions. As a consequence, this peapod‐like structure exhibits a stable discharge capacity of 1434 mAh g^?1 (at 100 mA g^?1) and 806 mAh g^?1 (at 200 mA g^?1) over 100 cycles as anode materials for LIBs and SIBs, respectively. More importantly, a stable capacity of 958 mAh g^?1 after 1000 cycles and 396 mAh g^?1 after 1500 cycles can be achieved for LIBs and SIBs, respectively, at a large current density of 2000 mA g^?1. This study provides a promising strategy for developing long‐cycle‐life LIBs and SIBs.     

A Chemical Precipitation Method Preparing Hollow–Core–Shell Heterostructures Based on the Prussian Blue Analogs as Cathode for Sodium‐Ion Batteries

Prussian blue and its analogs are regarded as the promising cathodes for sodium‐ion batteries (SIBs). Recently, various special structures are constructed to improve the electrochemical properties of these materials. In this study, a novel architecture of Prussian blue analogs with large cavity and multilayer shells is investigated as cathode material for SIBs. Because the hollow structure can relieve volume expansion and core–shell heterostructure can optimize interfacial properties, the complex structure materials exhibited a highly initial capacity of 123 mA h g^?1 and a long cycle life. After 600 cycles, the reversible capacity of the electrode still maintains at 102 mA h g^?1 without significant voltage decay, indicating a superior structure stability and sodium storage kinetics. Even at high current density of 3200 mA g^?1, the electrode still delivers a considerable capacity above 52 mA h g^?1. According to the electrochemical analysis and ex‐situ measurements, it can be inferred that the enhanced apparent diffusion coefficient and improved insertion/extraction performance of electrode have been obtained by building this new morphology.     

Sulfur-Bridged Bonds Heightened Na-Storage Properties in MnS Nanocubes Encapsulated by S-Doped Carbon Matrix Synthesized via Solvent-Free Tactics for High-Performance Hybrid Sodium Ion Capacitors

The exploitation of electrode materials with ability to balance capacity and kinetics between cathode and anode is a challenge for sodium-ion hybrid capacitors (SIHCs). Mn-based anode materials are limited by poor electrical conductivity, sluggish reaction kinetics, large volume variation, weak cycling stability, and inferior reversible capacity. Herein, MnS nanocubes encapsulated in S-doped porous carbon matrix (MSC) with strong sulfur-bridged bond interactions (C S Mn) are successfully synthesized by solvent-free tactics. The C S Mn bonds generated between MnS and carbon significantly inhibit the aggregation of nanostructural MnS cubes, restrict the volume expansion, and stabilize the nanostructure, which improves the Na⁺ storage reversibility and stability. Moreover, S-doped porous carbon enhances the electrical conductivity and electrons/ions diffusion rate, which boosts a fast kinetic reaction. As expected, MSC anode presents an outstanding reversible capacity of 600 mAh g^-1 at 0.2 A g^-1 and a long-term stable capacity of 357 mAh g^-1 for 1000 cycles at a high current density of 10 A g^-1 in sodium-ion batteries (SIBs). The as-assembled SIHCs deliver a high energy density of 109 W h kg^-1 and a high power output of 98 W kg^-1, with 88% capacity retention at 2 A g^-1 after 2000 cycles and practical applications (55 LEDs can be lighted for 10 min).     

钠离子电池无粘结剂二氧化钛负极材料的合成

作为电池的重要组成部分,电极材料直接影响电池的能量密度。电极材料在制作过程中往往会添加粘结剂以稳定极片结构,但粘结剂的加入会降低电极材料的比容量,影响其离子迁移速率。通过在经水热反应刻蚀的钛箔/网上原位生长二氧化钛(TiO 2)得到无粘结剂TiO 2/Ti纳米线阵列电极,并系统地研究不同钛基底及水热反应温度对TiO 2/Ti纳米线阵列电极物理性能和电化学性能的影响。结果表明,不同钛基底及水热反应温度均对生长的TiO 2纳米线的形貌和电化学性能有重要影响。其中通过220℃水热反应生长在钛网(0.15 mm)上的TiO 2纳米线呈蛛网状,具有较大的比表面积,属于锐钛矿型TiO 2,储钠过程主要由赝电容效应控制,且具有优秀的电化学性能:首周放电比容量为986 mAh g^-1,库伦效率为21.7%;随后放电比容量逐渐稳定在240 mAh g^-1左右;循环200周后放电比容量仍能达到228 mAh g^-1,库伦效率稳定在99.3%左右;即使在3200 mA g^-1的超大电流密度下,放电比容量仍能达到152 mAh g^-1。无粘结剂电极材料极大可以有限地提升电极材料的比容量,对未来高能量密度电池体系的设计具有一定的理论意义和参考价值。     

In-situ encapsulation of α-Fe2O3 nanoparticles into ZnFe2O4 micro-sized capsules as high-performance lithium-ion battery anodes

Transition metal oxides as anode materials for high-performance lithium-ion batteries suffer from severe capacity decay,originating primarily from particle pulverization upon volume expansion/shrinkage and the intrinsically sluggish electron/ion transport.Herein,in-situ encapsulation of α-Fe2O3 nanoparticles into micro-sized ZnFe2O4 capsules is facilely fulfilled through a co-precipitation process and followed by heat-treatment at optimal calcination temperature.The porous ZnFe2C4 scaffold affords a synergistic confinement effect to suppress the grain growth of α-Fe2O3 nanocrystals during the calcination process and to accommodate the stress generated by volume expansion during the charge/discharge process,leading to an enhanced interfacial conductivity and inhibit electrode pulverization and mechanical failure in the active material.With these merits,the prepared α-Fe2O3/ZnFe2O4 composite delivers prolonged cycling stability and improved rate capability with a higher specific capacity than sole α-Fe2O3 and ZnFe2O4.The discharge capacity is retained at 700 mAh g-1 after 500 cycles at 200 mA g-1 and 940 mAh g-1 after 50 cycles at 100 mA g-1.This work provides a new perspective in designing transition metal oxides for advanced lithium-ion batteries with superior electrochemical properties.     

Controllable Design of MoS2 Nanosheets Grown on Nitrogen‐Doped Branched TiO2/C Nanofibers: Toward Enhanced Sodium Storage Performance Induced by Pseudocapacitance Behavior

In this work, expanded MoS₂ nanosheets grown on nitrogen‐doped branched TiO₂/C nanofibers (NBT/C@MoS₂ NFs) are prepared through electrospinning and hydrothermal treatment method as anode materials for sodium‐ion batteries (SIBs). The continuous 1D branched TiO₂/C nanofibers provide a large surface area to grow expanded MoS₂ nanosheets and enhance the electronic conductivity and cycling stability of the electrode. The large surface area and doping of nitrogen can facilitate the transfer of both Na⁺ ions and electrons. With the merits of these unique design and extrinsic pseudocapacitance behavior, the NBT/C@MoS₂ NFs can deliver ultralong cycle stability of 448.2 mA h g^?1 at 200 mA g^?1 after 600 cycles. Even at a high rate of 2000 mA g^?1, a reversible capacity of 258.3 mA h g^?1 can still be achieved. The kinetic analysis demonstrates that pseudocapacitive contribution is the major factor to achieve excellent rate performance. The rational design and excellent electrochemical performance endow the NBT/C@MoS₂ NFs with potentials as promising anode materials for SIBs.     

ZIF‐8@ZIF‐67‐Derived Nitrogen‐Doped Porous Carbon Confined CoP Polyhedron Targeting Superior Potassium‐Ion Storage

Potassium ion batteries (KIB) have become a compelling energy‐storage system owing to their cost effectiveness and the high abundance of potassium in comparison with lithium. However, its practical applications have been thwarted by a series of challenges, including marked volume expansion and sluggish reaction kinetics caused by the large radius of potassium ions. In line with this, the exploration of reliable anode materials affording high electrical conductivity, sufficient active sites, and structural robustness is the key. The synthesis of ZIF‐8@ZIF‐67 derived nitrogen‐doped porous carbon confined CoP polyhedron architectures (NC@CoP/NC) to function as innovative KIB anode materials is reported. Such composites enable an outstanding rate performance to harvest a capacity of ≈200 mAh g^?1 at 2000 mA g^?1. Additionally, a high cycling stability can be gained by maintaining a high capacity retention of 93% after 100 cycles at 100 mA g^?1. Furthermore, the potassium ion storage mechanism of the NC@CoP/NC anode is systematically probed through theoretical simulations and experimental characterization. This contribution may offer an innovative and feasible route of emerging anode design toward high performance KIBs.