锂离子电池用硅基复合材料的研究进展

锂离子电池硅负极材料具有很高的理论比容量(4200 m Ah/g),但其在充放电过程中巨大的体积变化导致循环性能很差,同时较低的电导率也限制了硅在锂离子电池中的应用前景。将硅与其它材料进行复合是改善硅基负极材料循环稳定性、提高其倍率性能的主要途径。文章综述了近年来硅基复合材料的研究进展,以期为硅基复合材料的研究提供参考。     

锂离子电池硅基负极黏结剂的研究新进展

硅具有较高的理论比容量,被认为是极具应用前景的锂离子电池负极材料。然而,硅在充放电过程中会产生巨大的体积变化,导致电极粉化脱落和容量的迅速下降,限制了硅基负极材料的应用。黏结剂是锂离子电池中一个不可或缺的组成部分,对体积变化较大的硅基负极而言,除了满足作为锂离子电池黏结剂的基本要求外,对黏结剂的结构和性能又提出了新的要求,黏结剂的选择对于增强硅基电极结构的稳定性并实现长期循环具有更加重要的意义。总结了近年来硅基负极材料黏结剂的研究进展,重点介绍了用于硅基负极材料的交联类黏结剂、导电类黏结剂和自修复类黏结剂等几种黏结剂的性能特点和应用,为选择和设计更加适合的硅基负极黏结剂提供研究建议。     

锂离子电池硅基负极黏结剂的研究新进展

硅具有较高的理论比容量,被认为是极具应用前景的锂离子电池负极材料。然而,硅在充放电过程中会产生巨大的体积变化,导致电极粉化脱落和容量的迅速下降,限制了硅基负极材料的应用。黏结剂是锂离子电池中一个不可或缺的组成部分,对体积变化较大的硅基负极而言,除了满足作为锂离子电池黏结剂的基本要求外,对黏结剂的结构和性能又提出了新的要求,黏结剂的选择对于增强硅基电极结构的稳定性并实现长期循环具有更加重要的意义。总结了近年来硅基负极材料黏结剂的研究进展,重点介绍了用于硅基负极材料的交联类黏结剂、导电类黏结剂和自修复类黏结剂等几种黏结剂的性能特点和应用,为选择和设计更加适合的硅基负极黏结剂提供研究建议。     

锂离子电池硅负极粘结材料的研究进展

硅基负极材料因具有较高的理论比容量 4200 mAh/g，已成为国内外新能源锂离子电池负极材料领域研究热点课题。然而，由于硅基材料体积膨胀率高达400%，经多次充放电循环后，硅颗粒会发生破裂和粉化使其在电极基体上易脱落，从而导致电池容量衰减快、寿命短的技术缺陷。为缓解硅颗粒巨大体积变化产生的应力以及维持电极完整性，国内外科学研究者们从电池组成上出发，对活性材料、导电剂、粘结剂、电解液等进行系统研究，其中对聚合物粘结剂改性是一种实现其高寿命、抗衰减的有效手段之一。基于锂离子硅基负极材料优异特性及粘结材料的研究现状，综述了硅基负极组成、结构、性能、作用原理、分子间作用机制以及负极粘结剂的分子结构设计，探讨其对硅基锂离子电池电化学性能的影响规律，为锂离子电池硅基负极粘结材料的应用与开发提供理论和实践指导。     

不同导电剂对硅碳复合负极性能的影响

导电剂的添加对负极材料在电池的循环性能中能否发挥其最优的性能起重要作用.文章以纳米硅碳复合负极材料为研究对象,研究了KS-6(导电炭黑)及SUPER-P(导电石墨)两种导电剂对硅碳复合负极材料电化学性能的影响.通过扫描电镜、电池测试系统分析了两种导电剂、负极片的形貌及负极片的电化学性能.结果表明:添加粒度细小的球形状的...     

石墨烯复合硅碳负极材料及其高能量密度锂离子电池研究获进展

正动力电池、消费类电池等终端产品对高能量密度锂离子电池的需求日益增强。目前,产业界主要采取硅碳复合路线来提升硅基负极应用水平,450 m Ah/g以下的硅碳复合负极材料在循环性、倍率性等方面基本能够满足应用要求;450 mAh/g以上的硅基负极应用还存在技术难点。高比容量、长循环稳定的硅碳复合负极材料开发充满挑战。     

锂离子电池大容量硅基负极材料的研究进展

高容量锂离子电池是目前新能源电池的研究重点之一。由于硅的理论容量(4 200mAh/g)是石墨电极材料容量(372mAh/g)的十倍以上,因而成为锂离子电池负极材料的研究热点。然而,在充放电过程中,由于硅电极体积变化较大,可造成活性物质的破坏和失效,导致其循环性能变差。此外,硅的电导率较低,并且与传统电解质的相容性较差。这些缺点严重影响了硅的电化学性能,限制了其在锂离子电池领域的广泛应用。综述了锂离子电池硅基负极材料的研究进展,探讨了高性能硅基复合电极材料的制备方法。     

锂离子电池硅/碳复合负极材料的研究进展

负极材料是制约锂离子电池发展的重要因素之一.硅/碳复合材料储锂容量高、循环稳定性好,是目前制备新型锂离子电池负极材料的研究热点.介绍了硅/碳复合材料的不同制备方法和复合结构以及优良的电化学性能,综述了硅/碳复合材料的研究进展,并对未来的发展方向进行了展望.     

TiO_2基锂离子电池复合负极材料的研究进展

TiO_2锂离子电池负极材料以其安全性高而著称,其被设计为各种纳米结构并与其他导电性好的材料制备成复合材料,以弥补其导电、导锂能力的不足。本文针对近年来TiO_2基复合材料作为锂离子电池负极材料的研究现状,介绍了碳类、硅类和金属类材料与TiO_2进行复合制备负极材料的可行方法,并分别分析了这3类材料的优缺点:碳类负极材料技术成熟,但有易燃的缺点;硅类负极材料理论容量高,但循环性能差且安全性不好;金属类负极材料普遍导电性好,且易与其他材料合金化,但循环性能差。最终提出,由于碳类负极材料技术成熟,且TiO_2可弥补其易燃的缺点;结合碳基材料优良导电性能与TiO_2优异安全性能的复合材料最有望实现工业化,将是锂离子电池领域重要的研究方向之一。     

锂离子电池负极用碳/硅复合材料的研究进展

硅(Si)因具有资源丰富、理论容量高、绿色环保等优点成为世界上最具有前景的锂离子电池负极材料之一。但硅的导电性能差,且在合金化/去合金化过程中会发生剧烈的体积膨胀导致电池循环稳定性严重下降。碳材料(C)导电性能优异且结构稳定。将C和Si进行复合,可得到容量高且循环性能好的锂离子电池负极材料。本综述从材料的制备方法着手,总结了锂离子电池C/Si复合负极材料的最新研究进展,探讨了制备方法、材料结构对C/Si复合负极材料储锂性能的影响。     

Mass production of three-dimensional hierarchical microfibers constructed from silicon–carbon core–shell architectures with high-performance lithium storage

In this work, a facile approach is reported to mass produce highly porous fibers constructed from silicon–carbon core–shell structures. The C–Si microfibers are prepared using a modified electrospinning deposition method (ESD), and subsequent calcination of the carbon shells. Benefited from the step of vacuum drying, the unnecessary solvent left in the precursor will volatilize, resulting in the uniform three-dimensional hierarchical microfibers constructed from silicon–carbon core–shell architectures. The uniform covering layers of carbon formed by decomposition of polymer contribute to the improvement of conductivity and alleviation of volume change. The pores in the microfibers are helpful for the diffusion of electrolyte. When evaluated as an anode material for lithium-ion batteries, the C–Si microfibers exhibit improved reversibility and cycling performance compared with the commercial Si nanoparticles. A high capacity of 860 mAh g⁻¹ can be retained after 200 cycles at a current rate of 0.3 C. The rate capability of the C–Si microfibers is also improved. The special structure is believed to offer better structural stability upon prolonged cycling and to improve the conductivity of the material. This simple strategy using the modified ESD method could also be applied to prepare other porous energy materials.     

S-doped crosslinked porous Si/SiO2 anode materials with excellent lithium storage performance synthesized via disproportionation

The volume expansion during cycling and low electrical conductivity of a Si anode limit its commercial development. Nanostructure can effectively alleviate the volume expansion and doping can increase the electrical conductivity of silicon. Hence, in this paper, uniformly S-doped crosslinked porous Si/SiO₂ (S-doped pSi/SiO₂) were prepared by the disproportionation reaction of SiO at a high temperature. As a bifunctional additive, sulphur can be used to prepare crosslinked porous silicon by a silicon-sulphur reaction. Furthermore, sulphur can improve the conductive properties of the bulk Si via doping. At the same time, residual SiO₂ can also be used as a buffer material. This strategy not only provides space for the volume expansion of silicon, but also enhances its electrical conductivity and improves charge transfer. Consequently, the S-doped pSi/SiO₂ anode exhibits superior cycling capacity and rate performance (1035 mAh·g^?1 at 1 A g^?1 after 300 cycles and an exceptional rate performance of 1233 mAh·g^?1 at 2 A g^?1). Moreover, the electrochemical performance of the S-doped pSi/SiO₂//LiFePO₄ full cell was also evaluated, which exhibits favourable lithium storage performance.     

Graphene/nanosized silicon composites for lithium battery anodes with improved cycling stability

Graphene/nanosized silicon composites were prepared and used for lithium battery anodes. Two types of graphene samples were used and their composites with nanosized silicon were prepared in different ways. In the first method, graphene oxide (GO) and nanosized silicon particles were homogeneously mixed in aqueous solution and then the dry samples were annealed at 500 °C to give thermally reduced GO and nanosized silicon composites. In the second method, the graphene sample was prepared by fast heat treatment of expandable graphite at 1050 °C and the graphene/nanosized silicon composites were then prepared by mechanical blending. In both cases, homogeneous composites were formed and the presence of graphene in the composites has been proved to effectively enhance the cycling stability of silicon anode in the lithium-ion batteries. The significant enhancement on cycling stability could be ascribed to the high conductivity of the graphene materials and absorption of volume changes of silicon by graphene sheets during the lithiation/delithiation process. In particular, the composites using thermally expanded graphite exhibited not only more excellent cycling performance, but also higher specific capacity of 2753 mAh/g because the graphene sheets prepared by this method have fewer structural defects than thermally reduced GO.     

3D heterostructured architectures of Co(3)O(4) nanoparticles deposited on porous graphene surfaces for high performance of lithium ion batteries

Control of structure and morphology in electrode design is crucial for creating efficient transport pathways of ions and electrons in high-performance energy storage devices. Here we report the fabrication of high-performance anode materials for lithium-ion batteries based on a 3D heterostructured architecture consisting of Co(3)O(4) nanoparticles deposited onto porous graphene surfaces. A combination of replication and filtration processes - a simple and general method - allows a direct assembly of 2D graphene sheets into 3D porous films with large surface area, porosity, and mechanical stability. The polystyrene spheres are employed as sacrificial templates for an embossing technique that yields porous structures with tunable pore sizes ranging from 100 nm to 2 μm. Co(3)O(4) nanoparticles with high-energy storage capacity can be easily incorporated into the pore surfaces by a simple deposition strategy, thereby creating a 3D heterogeneous Co(3)O(4)/graphene film. In particular, we exploit the 3D Co(3)O(4)/graphene composite films as anode materials for lithium ion batteries in order to resolve the current issues of rate capability and cycling life. This unique heterogeneous 3D structure is capable of delivering excellent Li(+) ion storage/release and displays the following characteristics: a high rate capability of 71% retention even at a high current rate of 1000 mA g(-1) and a good cycling performance with 90.6% retention during 50 cycles. The versatile and simple nature of preparing 3D heterogeneous graphene films with various functional nanoparticles can be extended to overcome the major challenges that exist for many electrochemical devices.     

Carbon-coated silicon as anode material for lithium ion batteries: advantages and limitations

Carbon coating of silicon powder was studied as a means of preparation of silicon-based anode material for lithium ion batteries. Carbon-coated silicon has been investigated at various cycling modes vs. lithium metal. Ex situ X-ray data suggest that there is irreversible reduction of crystallinity of the silicon content. Since carbon layer preserving the integrity of the particle, the reversibility of the structural changes in the amorphous state Li-Si alloy provides the reversible capacity. The progressively decreased Coulomb efficiency with cycling indicates that more and more lithium ions are trapped in some form of Li-Si alloy and become unavailable for extraction. This is the main factor for the capacity fading during cycling. Qualitative studies of the impedance spectra of the electrode material at the first cycle for the fresh anode and at the last cycle after the anode capacity faded considerably and provide further support for this model of fading mechanism.     

Preparation of graphene supported porous Si@C ternary composites and their electrochemical performance as high capacity anode materials for Li-ion batteries

Graphene supported porous Si@C ternary composites had been synthesized by various routes and their structural, morphological and electrochemical properties were investigated. Porous Si spheres coated with carbon layer and supported by graphene have been designed to form a 3D carbon conductive network. Used as anode materials for lithium ion batteries, graphene supported porous Si@C ternary composites demonstrate excellent electrochemical performance and cycling stability. The first discharge capacity is 2184.7 mA h/g at a high current density of 300 mA/g. After 50 cycles, the reversible capacity is 652.4 mA h/g at a current density of 300 mA/g and the coulomb efficiency reaches at 98.7%. Due to their excellent electrochemical properties, graphene supported porous Si@C ternary composites can be a kind of promising anode materials for lithium ion batteries.     

A review study on the recent advances in developing the heteroatom-doped graphene and porous graphene as superior anode materials for Li-ion batteries

Graphene materials, with their distinctively fascinating physicochemical properties, have been receiving great attention as favorable anode materials for use in Li-ion batteries (LIBs). However, the high affinity of graphene nanosheets to restack and agglomerate during electrode assembly reduces the deliverable specific capacity due to the limited available surface area and active sites for Li-ion storage. Furthermore, the high aspect ratio of graphene nanosheets could result in long transport pathways for Li-ions and consequently limiting the rate performance. These drawbacks can be significantly improved via the functionalization of graphene by various heteroatoms and also the formation of porous graphene, adding unique beneficial properties to the inherent characteristics of graphene. Here, a comprehensive review of porous and/or heteroatom doped graphene anode materials for LIBs is presented, which summarizes in detail the main recent literature from their procedure, optimum synthesis parameters, relevant mechanisms, and the obtained morphology/structure to their electrochemical performance as the LIBs anode. Finally, the research gaps are proposed. This review will promote the basic understanding and further development of porous and/or doped graphene materials as anodes for LIBs.     

Electrochemical stability of silicon/carbon composite anode for lithium ion batteries

Silicon/carbon composite anode materials were prepared by pyrolyzing the phenol-formaldehyde resin (PFR) mixed with silicon and graphite powders. Scanning electron microscopic (SEM) observation showed that the morphology stability of the composite electrodes can be retained during cycling. A structure evolution mechanism is proposed to illuminate the enhancement of cycleability of the composite electrode. The composite used as anode material for lithium ion batteries possesses a reversible capacity of over 700 mAh/g.     

高性能钠离子电池负极材料的研究进展

负极材料的研究是钠离子电池实现商业化生产的关键要素之一，近年来已经取得了突破性进展。但是较大半径的钠离子在嵌/脱过程中对负极材料结构的影响非常大，进而导致可逆容量迅速降低。本文系统综述了钠离子电池负极材料的最新研究成果，阐述了碳基材料、钛基化合物、合金材料、金属化合物和有机化合物5类负极材料的制备工艺，并分析了这些材料的性能特点：碳基材料的研发技术成熟，但比容量和倍率性能有待提高；钛基化合物的结构性能良好，倍率性能出色，但存在比容量较低的缺点；合金材料和金属化合物都具有较高的理论比容量，但循环性能较差；有机化合物的研发尚处于起步阶段，有待深入研究。基于现有的研究基础，总结了材料的改性方法和取得的效果，并展望了钠离子电池负极材料的研究方向，分析指出表面碳包覆可以提升材料的电子传导性，纳米结构可以缩短钠离子的传输途径，多孔形貌有利于电解质对材料的浸润，而元素掺杂可以提升材料的反应活性，最终获得高性能钠离子电池负极材料。