锂离子电池硅基负极材料的最新研究进展

硅基材料因具有目前最高的理论比容量、合适的嵌锂平台、大储量等优点,引起了众多研究者的关注,成为最具潜力的下一代锂离子电池的负极材料. 但是硅在嵌锂过程中巨大的体积变化,容易破坏电极结构的稳定性,使电极循环性能迅速衰减,这对硅基材料的应用造成了很大的阻碍. 本文主要针对近年来在硅电极自身的结构（包括：多孔硅基复合材料的合成、硅粘结剂的选择,无粘结剂的纳米硅电极的制备）以及电解液添加剂的选择两大方面的最新研究进展进行总结与评述.     

Ni3S2@碳纳米管复合材料的制备及其储钠性能

采用一步固相煅烧工艺制备了碳纳米管原位封装Ni₃S₂纳米颗粒（Ni₃S₂@CNT）,并研究了其作为钠离子电池（SIBs）负极材料的电化学性能. 通过X射线衍射（XRD）、扫描电子显微镜（SEM）、透射电子显微镜（TEM）、循环伏安测试、恒流充放电以及交流阻抗等研究了Ni₃S₂@CNT的物相结构、形貌特征以及电化学性能. 电化学测试表明,材料在100 mA·g ^-1电流密度下,放电容量可以达到541.6 mAh·g ^-1,甚至在2000 mA·g ^-1的大电流密度下其放电比容量也可以维持在274.5 mAh·g ^-1. 另外,材料在100 mA·g ^-1电流密度下,经过120周充放电循环后其放电和充电比容量仍然可以保持在374.5 mAh·g ^-1和359.3 mAh·g ^-1,说明其具有良好倍率性能和循环稳定性能. 良好的电化学性能归因于这种独特的碳纳米管原位封装Ni₃S₂纳米颗粒结构. 碳纳米管不但可以提高复合材料的导电性,也可以缓冲Ni₃S₂纳米颗粒在反复充放电过程中产生的体积膨胀效应,明显改善了Ni₃S₂@CNT负极复合材料的电化学性能.     

碳布负载的缺氧型Na2Ti3O7纳米带阵列作为高性能柔性钠离子电池负极材料

作为锂离子电池的理想替代品,钠离子电池因具有能源储备丰富、成本低廉等优点而受到人们的广泛关注。柔性便携式电子产品的发展亟需柔性储能器件的研制。因此,发展一种廉价、高性能的柔性钠离子电池负极材料成了科研工作者的共同目标。在此项工作中,我们通过简单的水热合成和热还原法发展了一种以柔性碳布为基底,与缺氧型的Na₂Ti₃O₇纳米带(NTO)构成三维阵列结构的新型柔性钠离子电池负极材料。复合材料(R-NTO/CC)的导电性和活性位点得到提高,电化学性能也大幅提升,在200 mA·cm^-2的电流密度下,实现100 mAh·cm^-2的面积比容量,且经过200次循环后仍保留最初电容值的80%。此外,这种电极还具有优良的倍率性能,当电流密度提高到400 mA·cm^-2时,仍保持69.7 mAh·cm^-2的面积比容量,是未引入氧空位材料的三倍之多。这种三维缺氧的电极材料可有效提高载流子浓度,缩短离子传输通道,从而大幅提升电极的电化学性能。此工作为设计合成高储钠性能的新型的负极材料提供了一种实用有效的策略。     

Binder-free carbon fiber/TiNb2O7 composite electrode as superior high-rate anode for lithium ions batteries

Carbon fibre supported titanium niobium oxide (TiNb₂O₇) composite electrodes are prepared via a simple solvothermal method and show superior high-rate performance with large capacity and good cycling performance.     

基于不同前驱体制备的硬碳负极材料的储锂性能

以聚丙烯腈、石油沥青和花生壳为前驱体,在1200℃下碳化制备三种不同的硬碳材料.通过扫描电子显微、X射线衍射、氮气吸附/脱附测试和拉曼光谱等方法探究不同前驱体所制备的硬碳材料的表面形貌和物相结构.通过恒流充放电测试考察了这三种硬碳负极材料的电化学性能.结果表明,花生壳基硬碳的初始放电比容量最高,但首圈库仑效率最低,石油...     

水热法制备锂电池Si@C负极材料的工艺优化研究

水热法是广泛应用于锂离子电池Si@C电极材料的一种制备方法,其反应条件是影响产物最终形貌和性能的重要因素, 采取最佳的反应工艺可以大大提升材料的电化学性能。本研究中, 使用葡萄糖作为碳源, 光伏切割废料硅为硅源, 探究了水热法制备核壳结构Si@C电极材料的最优工艺, 分别研究了温度、 原料浓度、 反应时间和原料比例对产物的形貌、 性能的影响以及相互之间的关系, 并得到最佳反应条件。在该条件下(葡萄糖浓度为0.5 mol·L^-1, 硅与葡萄糖重量比为0.3:1, 反应温度190 ^oC, 反应时间9 h), 得到了包覆完整、 粒径适中的Si@C电极材料(CS190-3), 对以该样品为负极的扣式半电池进行电化学测试, 在655 mA·g^-1的电流密度下, 其首圈放电比容量为3369.5 mAh·g^-1, 经过500次循环剩余容量为1405.0 mAh·g^-1。倍率测试中, 在6550 mA·g^-1的电流密度下,其剩余容量为937.1 mAh·g^-1,当电流密度恢复至655 mA·g^-1时,电池放电比容量仍可恢复至1683.0 mAh·g^-1。     

Electrospun Sb2Se3@C nanofibers with excellent lithium storage properties

Antimony-based materials have become promising anodes within lithium-ion batteries(LIBs)due to their low cost and the high theoretical capacity.However,there is a potential to further enhance the electrochemical performance of such antimony-based materials.Herein,Sb2Se3@C nanofibers(Sb2Se3@CNFs)are designed and obtained via a novel electrospinning method.Upon electrochemically testing as an anode within LIBs,the Sb2Se3@CNFs(annealed at 600℃)delivers a remarkably good cycling performance of 625 mAh/g at 100 mA/g after 100 cycles.Moreover,it still remains at 490 mAh/g after 500 cycles with an applied current density of 1.0 A/g.The excellent performance of the Sb2 Se3@CNFs can be attributed to the fact that the N-doped C matrices not only remit the volume expansion of materials,but also enhance the electrical and ionic conductivity thusly increasing the lithium-ion diffusion.The obtained Sb2Se3@CNFs are promising anode for LIBs in the future.     

锂离子电池用三维氧化锡/石墨烯水凝胶负极材料

通过溶液水解反应在氧化石墨烯表面引入氧化锡(Sn O2)纳米颗粒,再经过自组装作用形成具有三维结构的氧化锡/石墨烯水凝胶(Sn O2-GH)负极材料。其中三维多孔的石墨烯水凝胶为碳质缓冲基体,Sn O2纳米颗粒为活性物质,其颗粒尺寸为2-3 nm,均匀分布在石墨烯层上,担载量可以达到54%(w,质量分数)。直接将该材料用作锂离子电池负极时,在5000 m A?g~(-1)的大电流密度下循环60次容量稳定在500 m Ah?g~(-1),电流减小到50 m A?g~(-1)循环80次后容量仍高达865 m Ah?g~(-1)。这些优异的循环稳定性和大电流充放电性能主要得益于三维石墨烯水凝胶的疏松、多孔结构和良好的导电性。石墨烯水凝胶能够提高电极比表面积,保证电解液对电极的浸润程度;内部空隙能够为锂离子的传输提供快速通道,缩短离子传输距离和时间。同时丰富的内部空间能够有效避免Sn O2纳米颗粒团聚,缓冲Sn O2巨大体积膨胀,维持电极结构的稳定性,是一种非常适于大电流充放电的锂离子电池负极材料。     

基于水凝胶衍生的硅/碳纳米管/石墨烯纳米复合材料及储锂性能

通过氧化石墨烯(GO)和壳聚糖(Cs)之间的氢键以及静电作用形成GO水凝胶,从而将纳米硅颗粒和碳纳米管(CNT)原位包封于其中,再经冷冻干燥及随后的热处理制得三维硅/碳纳米管/石墨烯(Si-CNT@G)纳米复合材料。采用X射线衍射(XRD)、扫描电子显微镜(SEM)和透射电子显微镜(TEM)、热重分析(TGA)等技术对制得样品的物相、结构和微观形貌等进行了表征。结果表明,所得复合材料在CNT纵横交织的石墨烯网络中,均匀地分布着纳米硅颗粒。当作为锂离子电池的负极材料时,在两种碳介质的协同作用下,有效缓冲硅材料在充放电过程中脱/嵌锂引起的体积变化,缩短了锂离子和电子传输的距离,Si-CNT@G复合材料表现出较好的循环稳定性以及倍率性能。在500 m A·g~(-1)的充放电电流密度下,经过200圈循环后,其放电比容量仍高达673.7 m Ah·g~(-1),容量保持率高达97%;即使将充放电电流密度升至2000 m A·g~(-1)时,该复合材料仍保持有566.9 m Ah·g~(-1)的高可逆放电比容量。独特的制备方法和优越的储锂性能,使得Si-CNT@G纳米复合材料成为理想的高性能锂离子电池负极材料的候选.     

MOF-derived Core-Shell CoP@NC@TiO2 Composite as a High-Performance Anode Material for Li-ion Batteries

Transition-metal phosphides have been regarded as promising anode materials for high-energy lithium-ion batteries (LIBs) due to their high capacity and low cost. However, the mechanical pulverization and resultant capacity fade critically limit their further development. Here, we have designed an innovative core-shell CoP@NC@TiO₂ composite with an exotic rhombic dodecahedral morphology derived from ZIF-67 precursor, which combines both advantages from TiO₂ with excellent cycling stability and CoP with high capacity. The additional MOF-derived N-doped carbon framework is considered to improve the electrical conductivity and accommodate the volume expansion of CoP particles. Moreover, the outer TiO₂ shell can also buffer the mechanical stress and maintain the integrity of composite. With the unique structure, the core-shell CoP@NC@TiO₂ composite material exhibits excellent electrochemical performance with a considerable discharge specific capacity of 706.3 mAh g⁻¹ at a current density of 100 mA g⁻¹ after 200 cycles and outstanding rate capacity. Hence, our work demonstrates that this core-shell structure strategy combined with MOF-derived carbon framework could provide a practical pathway towards enhanced electrode materials for energy storage and conversion.     

Enhanced Anode Performances of Polyaniline-TiO(2)-Reduced Graphene Oxide Nanocomposites for Lithium Ion Batteries

Here, we report a three-layer-structured hybrid nanostructure consisting of transition metal oxide TiO(2) nanoparticles sandwiched between carbonaceous polymer polyaniline (PANI) and graphene nanosheets (termed as PTG), which, by simultaneously hindering the agglomeration of TiO(2) nanoparticles and enhancing the conductivity of PTG electrode, enables fast discharge and charge. It was demonstrated that the PTG exhibited improved electrochemical performance compared to pure TiO(2). As a result, PTG nanocomposite is a promising anode material for highly efficient lithium ion batteries (LIBs) with fast charge/discharge rate and high enhanced cycling performance [discharge capacity of 149.8 mAh/g accompanying Coulombic efficiency of 99.19% at a current density of 5C (1000 mA/g) after 100 cycles] compared to pure TiO(2). We can conclude that the concept of applying three-layer-structured graphene-based nanocomposite to electrode in LIBs may open a new area of research for the development of practical transition-metal oxide graphene-based electrodes which will be important to the progress of the LIBs science and technology.     

Fabrication of Nb2O5/C nanocomposites as a high performance anode for lithium ion battery

Nb₂O₅/C nanosheets are successfully prepared through a mixing process and followed by heating treatment.Such Nb₂O₅/C based electrode exhibits high rate performance and remarkable cycling ability, showing a high and stable specific capacity of ~380 mAh g^-1 at the current density of 50 mA g^-1(much higher than the theoretical capacity of Nb₂O₅).Further more,at a current density of 500 mA g^-1,the nanocomposites electrode still exhibits a specific capacity of above 150 mAh g^-1 after 100 cycles.These results suggest the Nb₂O₅/C nanocomposite is a high performance anode material for lithium-ion batteries.     

一步硫/磷热处理制备空心Co9S8/CoP/C纳米复合材料及其储钠性能研究

低成本、高性能的钠离子电池有望成为代替锂离子电池的下一代核心器件.但是开发出高比容量、高倍率的钠离子电池负极材料依然是瓶颈.本文通过水热/溶剂热法制备了Co基前驱体,然后将其一步硫/磷热处理制得具有空心多孔结构的h-Co₉S₈/CoP/C纳米复合材料.通过X-射线粉末衍射(XRD)、拉曼光谱(Raman)、扫描电镜(SEM)、透射电镜(TEM)和X-射线光电子能谱(XPS)等表征以确定纳米复合物的物相以及形貌特征.当h-Co₉S₈/CoP/C作为钠离子电池负极材料时,该电极材料展示了高的比容量(561 mAh g^-1@0.1 Ag^-1)、较好的循环性能(可逆比容量200 mAh g^-1@2 Ag^-1)和倍率性能.h-Co₉S₈/CoP/C之所以显示出良好的储钠性能,主要得益于其空心多孔结构不仅提供更多的空间缓解钠在反复嵌入和脱出过程造成的体积膨胀效应,而且可以缩短离子/电荷扩散途径以加快反应动力学,此外,Co₉S₈、CoP和C独特的电子结构优势得以共同发挥.     

Polydopamine-mediated synthesis of Si@carbon@graphene aerogels for enhanced lithium storage with long cycle life

The application of Si as the anode materials for lithium-ion batteries (LIBs) is still severely hindered by the rapid capacity decay due to the structural damage caused by large volume change (> 300%) during cycling. Herein, a three-dimensional (3D) aerogel anode of Si@carbon@graphene (SCG) is rationally constructed via a polydopamine-assisted strategy. Polydopamine is coated on Si nanoparticles to serve as an interface linker to initiate the assembly of Si and graphene oxide, which plays a crucial role in the successful fabrication of SCG aerogels. After annealing the polydopamine is converted into N-doped carbon (N-carbon) coatings to protect Si materials. The dual protection from N-carbon and graphene aerogels synergistically improves the structural stability and electronic conductivity of Si, thereby leading to the significantly improved lithium storage properties. Electrochemical tests show that the SCG with optimized graphene content delivers a high capacity (712 mAh/g at 100 mA/g) and robust cycling stability (402 mAh/g at 1 A/g after 1500 cycles). Furthermore, the full cell using SCG aerogels as anode exhibits a reversible capacity of 187.6 mAh/g after 80 cycles at 0.1 A/g. This work provides a plausible strategy for developing Si anode in LIBs.     

Synthesis of iron oxide cubes/reduced graphene oxide composite and its enhanced lithium storage performance

Fe₃O₄ is considered as a promising electrode material for lithium-ion batteries(LIBs) due to its low cost and high theoretical capacity(928 mAh/g).Nevertheless,the huge volume expansion and poor conductivity seriously hamper its practical applications.In this study,we use a facile hydrothermal reaction together with a post heat treatment to construct the three-dimensional heterostructured composite(Fe₃O₄/rGO) inwhich reduced graphene oxide sheets wraped the Fe₃O₄ submicron cubes as the conductive network.The electric conduction and electrode kinetics of lithium ion insertion/extraction reaction of the composite is enhanced due to the assist of conductive rGO,and thus the Listorage performance is obviously improved.The composite exhibits a reversible charge capacity of772.1 mAh/g at the current density of 0.1 A/g,and the capacity retention reaches 70.3% after400 cycles at0.5 A/g,demonstrating obviously higher specific capacity and rate capability over the Fe₃O₄ submicron cubes without rGO,and much superior cycling stability to the parent Fe_2 O_3 submicron cubes without rGO.On the other hand,as a synergic conductive carbon support,the flexible rGO plays an important role in buffering the large volume change during the repeated discharge/charge cycling.     

Sub-100 nm hollow SnO2@C nanoparticles as anode material for lithium ion batteries and significantly enhanced cycle performances

Rational designing and controlling of nanostructures is a key factor in realizing appropriate properties required for the high-performance energy fields. In the present study, hollow SnO₂@C nanoparticles (NPs) with a mean size of 50 nm have been synthesized in large-scale via a facile hydrothermal approach. The morphology and composition of as-obtained products were studied by various characterized techniques. As an anode material for lithium ion batteries (LIBs), the as-prepared hollow SnO₂@C NPs exhibit significant improvement in cycle performances. The discharge capacity of lithium battery is as high as 370 mAh g^-1, and the current density is 3910 mA g^-1(5 C) after 573 cycles. Furthermore, the capacity recovers up to 1100 mAh g^-1 at the rate performances in which the current density is recovered to 156.4 mA g^-1(0.2 C). Undoubtedly, sub-100 nm SnO₂@C NPs provide significant improvement to the electrochemical performance of LIBs as superior-anode nanomaterials, and this carbon coating strategy can pave the way for developing high-performance LIBs.     

TiC/C core/shell nanowires arrays as advanced anode of sodium ion batteries

High-perfo rmance anodes of sodium ion batteries(SIBs)largely depends on rational architecture design and binder-free smart hybridization.Herein,we report TiC/C core/shell nanowires arrays prepared by a one-step chemical vapor deposition(CVD)method and apply it as the anode of SIBs for the first time.The conductive TiC core is intimately decorated with carbon shell.The as-obtained TiC/C nanowires are homogeneously grown on the substrate and show core/shell heterostructure and porous architecture with high electronic conductivity and reinforced stability.Owing to these merits,the TiC/C electrode displays good rate performance and outstanding cycling performance with a capacity of 135.3 mAh/g at 0.1 A/g and superior capacity retention of 90.14%after 1000 cycles at 2 A/g.The reported strategy would provide a promising way to construct binder-free arrays electrodes for sodium ion storage.     

锂离子电池氧化亚硅负极结构优化和界面改性研究进展

氧化亚硅(SiO)作为锂离子电池负极材料,具有较高的理论比容量(~2043 mAh·g^-1)以及合适的脱锂电位(< 0.5 V),且原料储量丰富、制备成本较低、对环境友好,被认为是下一代高能量密度锂离子电池负极极具潜力的候选材料。然而,SiO在脱/嵌锂过程中存在着较严重的体积效应(~200%),易导致材料颗粒粉化、脱落,严重影响了SiO负极电极的界面稳定性和电化学性能。近年来,人们围绕SiO负极结构优化和界面改性开展了大量工作。本文先从SiO负极材料的结构特点出发,阐述了该材料面临的主要瓶颈问题;继而从SiO的结构优化、SiO/碳复合和SiO/金属复合等三方面,系统总结了迄今已有的SiO负极结构设计和界面调控策略,并分别对其方法特点、电化学性能以及二者间关联规律进行了比较和归纳,最后对SiO负极材料结构和界面改性的未来发展方向进行了展望。     

Two π-Conjugated Covalent Organic Frameworks with Long-Term Cyclability at High Current Density for Lithium Ion Battery

Organic lithium ion batteries (LIBs) are considered as one of the next-generation green electrochemical energy storage (EES) devices. However, obtaining both high capacity and long-term cyclability is still the bottleneck of organic electrode materials for LIBs because of weak structural and chemical stability and low conductivity. Covalent organic frameworks (COFs) show potential to overcome these problems owing to its good stability and high capacity. Herein, the synthesis and characterization of two π-conjugated COFs, derived from the Schiff-base reaction of 2,4,6-triaminopyrimidne (TM) respectively with 1,4-phthalaldehyde (PA) and 1,3,5-triformylbenzene (TB) by a mechanochemical process are presented. As anode materials for LIBs, the COFs exhibit favorable electrochemical performance with the highest reversible discharge capacities of up to 401.3 and 379.1 mAh g⁻¹ at a high current density (1 A g⁻¹), respectively, and excellent long-term cyclability with 74.8 and 72.7 % capacity retention after 2000 cycles compared to the initial discharge capacities.     

基于一体化正极与电解质膜的高性能固态电池

Lithium ion batteries (LIBs) are becoming the most popular energy storage systems in our society. However, frequently occurring accidents of electrical cars powered by LIBs have caused increased safety concern regarding LIBs. Solid-state lithium batteries (SSLBs) are believed to be the most promising next generation energy storage system due to their better in-built safety mechanisms than LIBs using flammable organic liquid electrolyte. However, constructing the ionic conducting path in SSLBs is challenging due to the slow ionic diffusion of Li ion in solid-state electrolyte, particularly in the case of solid-solid contact between the solid materials. In this paper, we demonstrate the construction of an integrated electrolyte and cathode for use in SSLBs. An integrated electrolyte and cathode membrane is obtained via simultaneous electrospinning and electrospraying of a polyacrylonitrile (PAN) electrolyte and a LiFePO₄ (LFP) cathode material respectively, for the cathode layer, followed by the electrospinning of PAN to prepare the electrolyte layer. The resultant integrated PAN-LFP membrane is flexible. Scanning electron microscopy and energy dispersive X-ray spectroscopy measurement results show that the electrode and electrolyte are in close contact with each other. After the integrated PAN-LFP membrane is filled with a succinonitrile-bistrifluoromethanesulfonimide (SN-LiTFSI) salt mixture, it is paired with a lithium foil metal anode electrode, and the resultant solid-state Li|PAN-LFP cell exhibits limited polarization and outstanding interfacial stability during long term cycling. That is, the Li|PAN-LFP cell presents a specific capacity of 160.8 mAh∙g⁻¹ at 0.1C, and 81% of the initial capacity is maintained after 500 cycles at 0.2C. The solid-state Li|PAN-LFP cell also exhibits excellent resilience in destructive tests such as cell bending and cutting.