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1.
以光伏电池生产废料中的大尺寸硅颗粒(200~800 nm)为原料,水性聚氨酯(PU)和聚苯胺(PANI)作为碳源,通过液相包裹法和低温热解法制备了不同结构碳复合的硅碳负极材料(SPU与SPU#PANI),分别研究了复合碳含量、微结构与元素掺杂对负极电化学性能的影响。SPU负极中碳复合量低,首次放电比容量高达2193.6 mAh/g,但循环稳定性差。经二级碳复合后的SPU#PANI导电性提高,在多孔碳微结构支撑作用下,不仅获得了较高的放电比容量(1488.8 mAh/g),而且经100次循环后SPU#PANI放电比容量保持在756.8 mAh/g以上,表现出良好的倍率性能。研究结果表明,大尺寸硅颗粒表面复合了具备多孔结构的碳后,不仅为硅充放电过程中的膨胀提供了缓冲,也为锂离子传输提供通道,有效地提升了硅基负极的电化学性能和稳定性。本工作采用的多级碳低温热解复合方法,可为锂离子电池硅基负极产业化技术发展提供重要的借鉴。  相似文献   

2.
硅基负极材料具有比容量高、电压平台低、环境友好、资源丰富等优点,有望替代石墨负极应用于下一代高比能锂离子电池。但是硅的导电性较差,且在充放电过程中存在巨大的体积效应,极易导致电极极化、材料粉化、SEI膜重构、库仑效率低和容量持续衰减。硅和碳复合能很好地综合两者的优势,形成结构稳定、循环性好及容量高的负极材料。本文从不同维度的硅(SiNPs、SiNTs/SiNWs、SiNFs、Bulk Si)与碳复合这一角度,综述了硅碳复合材料在结构设计、制备工艺、电化学性能等方面的最新研究进展,并对未来的硅碳复合材料的研究工作进行了展望。  相似文献   

3.
硅材料作为锂离子电池负极材料具有4200 mA·h/g的超高理论比容量,也因此成为了科研机构和高校的研究热点。但是硅基材料在脱嵌锂的过程中有着巨大的体积变化,膨胀收缩率达300%,这造成了电池在充放电过程中电极材料迅速坍塌,导致了电池的循环寿命大大缩短。为了解决这一问题,本文研究了一种通过水热方法,使石墨烯和碳、硅形成一个双层包覆的三维导电网络结构。实验证明,这种Si/C/G(Si/carbon/graphene)三层结构作为锂离子电池负极材料,表现出了优越的电化学性能,比如超长循环寿命、超大充放电倍率等。这种结构的电极片以0.2 A/g的电流密度充放循环50次,比容量在2469 mA·h/g以上;2 A/g的电流密度充放循环300次,比容量保持在1500 mA·h/g以上;此外在超大电流密度32 A/g的情况下测试,比容量保持在471 mA·h/g,并且具有超强的恢复能力,表现出了卓越的倍率性能,说明这种三维导电网络结构复合材料增加了原始材料的强度韧性及导电性。可见,本工作采用的方法、设计的复合材料结构在很大程度上抑制了硅材料作为负极材料的体积效应,在锂离子电池电极材料的研究发展上具有一定的借鉴意义。  相似文献   

4.
邓攀  陈程  张灵志 《新能源进展》2020,8(5):413-427
硅在自然界中储量丰富,其理论比容量高达4 200 mA∙h/g,已成为高能量密度锂离子电池负极材料的研究热点。但是Si作为负极材料也存在许多不足,最大的问题是电池充放电过程中,硅体积膨胀(高达300%),导致Si基负极材料粉化脱落、电池容量迅速衰减,其循环性能尚难以满足实际需求。通过研究开发硅基负极专用黏结剂材料,可以有效抑制循环过程中硅的体积变化,维持硅负极结构稳定,提升电池循环性能。本文综述了近年来硅基负极黏结剂材料的研究进展,主要从合成高分子聚合物黏结剂、天然高分子聚合物黏结剂、导电高分子聚合物黏结剂三个方面进行详细归纳总结,并介绍了本课题组在硅基负极黏结剂方面的部分研究成果,期望能为将来的硅基负极专用黏结剂的研究和应用提供一些思路。  相似文献   

5.
为了满足储能市场对高功率电池的需求,开发具有高功率性能的锂离子电池负极材料成为必然发展趋势。本文通过湿式合成法将软碳和硬碳的前驱体进行复合,开发了一种新型的复合碳锂离子电池负极材料。考察了其克比容量、库仑效率、倍率性能以及循环稳定性。用X射线粉末衍射(XRD)、拉曼、扫描电镜(SEM)以及透射电子显微镜(TEM)对所制备的复合碳材料的结构和表面形貌进行表征。结果表明,该复合碳材料同时具有软碳和硬碳的优点,且性能优于机械混合碳,在保持高比容量和高效率的前提下,倍率性能尤为突出,其2C容量可达154 m A·h/g,且2C/0.2C的容量保持率为64.2%;同时0.2C克比容量为240 m A·h/g,库仑效率为82%。经过5C充放电后,恢复0.2C小电流充放电后,容量保持率达99.8%,循环稳定性很好。XRD、拉曼以及透射电子显微镜的表征结果均表明软、硬碳在复合过程中不只是简单机械共混而是具有协同效应。  相似文献   

6.
硅因其超高的理论比容量,有望成为下一代高性能锂离子电池的负极材料.硅在充放电过程中的剧烈体积膨胀会引起颗粒粉化、SEI膜过量生长以及活性物质失去电接触等问题,最终导致容量快速衰减.开发新型硅负极黏结剂和硅碳复合是提升硅负极性能的重要策略.生物高分子材料成本低、环境友好且富含有机官能团,非常适合用来开发低成本、高性能硅负极黏结剂,也适合作为碳前体合成硅碳复合材料.本文综述了近年来基于生物高分子的硅负极黏结剂和以生物高分子为碳前体的硅碳复合材料的研究进展.本文重点介绍了基于海藻酸钠、壳聚糖、淀粉的硅负极黏结剂,总结出生物高分子基黏结剂的主要改性方法有接枝特殊官能团、与其他聚合物共混或交联.基于这些改性方法,可分别提升黏结剂的黏附性、导电子或离子能力以及实现3D网络结构的构建.本文重点归纳了以纤维素、壳聚糖、淀粉、木质素为碳前体的硅碳复合材料,分别介绍了这些复合材料的性质、结构特点,及其对电化学性能的影响.基于以上分析,本文也指出了当前基于生物高分子的硅负极黏结剂和以生物高分子为碳前体的硅碳复合材料的不足,为其下一步发展指明了方向.  相似文献   

7.
硅基材料由于具有超高的理论比容量,安全的嵌锂工作电位和廉价易得等诸多优点,是下一代高比能量电池体系最理想的负极材料。尽管硅基材料的研究已经进行很长时间,但是硅基材料嵌锂时巨大的体积膨胀,循环性能较差等问题一直难以得到有效解决。开发高性能硅基负极黏结剂是解决硅基材料应用问题的重要途径之一,具有“刚柔并济”结构特性的黏结剂分子能够有效抑制硅基材料结构膨胀粉化,保持电极导电网络的完整性,从而有效提升其循环性能。本文综述了硅基负极黏结剂的特性要求,新型硅基负极黏结剂的研究进展,并对该领域未来潜在的研究方向进行了展望:复合体系聚合物黏结剂的开发;特殊空间构型黏结剂的开发;新型导电黏结剂的开发;自支撑无黏结剂硅基负极的开发。  相似文献   

8.
纳米硅碳材料主要成分为纳米硅与碳材料,纳米硅具有较小的颗粒尺寸,其储锂容量较高,碳材料具有较高的电子电导,为复合材料提供较好的电子通道;同时将碳与硅材料复合后能缓和硅材料体积形变带来的应力变化;此外,碳作为包覆材料能有效稳定电极材料与电解液的界面,使SEI膜稳定生长。因此,硅碳复合材料有望替代石墨成为下一代高能量密度锂离子电池负极。本文简要介绍了纳米先导专项硅负极研究团队在纳米硅碳材料方面的研究进展。通过持续的研发与技术更新,目前低容量复合材料(380~450 mA·h/g)的反弹系数、效率、压实密度、加工性能皆不亚于目前商品石墨的水平;在高容量及超高容量材料(500~2000 mA·h/g)方面,通过精细的结构设计,循环性能和倍率性能等得到了较大提升。  相似文献   

9.
静电纺丝法由于具有工艺简单、功能多样等优点,是一种重要的制备一维锂钠离子电池纳米结构电极材料的方法。目前,已有大量利用静电纺丝技术制备高性能电极材料的研究报道,但具有系统性和针对性的综述论文尚十分有限。碳材料是最早被研究且已实现商业化的锂离子电池负极材料,硅材料则是理论容量最高的负极材料,因此,两者一直是学术界和工业界关注的重点;但碳材料理论容量低和硅材料体积变化大的问题严重阻碍了各自更广泛的实际应用。静电纺丝技术被证明是一种可以解决上述问题的十分有效的方法。因此,本文系统地综述了静电纺丝法制备的硅基和碳基纳米纤维在锂钠离子电池负极材料上的应用和发展,重点从静电纺丝原理、硅碳材料的设计及合成、结构的调控与优化、复合材料的制备到电化学性能的提高等方面作了详细介绍和讨论,同时也指出静电纺丝法在大规模生产中的不足及未来可能的发展方向。希望此综述可以为先进储能材料(尤其是硅基和碳基纳米电极材料)的设计和制备提供一些有益的指导和帮助。  相似文献   

10.
硅材料具有较高的理论容量,被视为发展高能量锂离子电池的重要材料之一。但是硅在充放电循环中体积变化较大,会导致负极材料粉化,严重影响电池的电化学性能。黏结剂作为电极的重要组成部分,对于稳定负极结构,改善电池性能具有重要作用。总结归纳了合成类聚合物、生物类聚合物等硅基负极黏结剂的研究进展,合成类聚合物主要包括聚丙烯酸类、聚偏二氟乙烯类以及导电类黏结剂,生物类聚合物主要包括羧甲基纤维素类、海藻酸钠类以及其他生物类黏结剂。分析了选择硅基负极黏结剂的条件,包括要有极性官能团、具有一定的弹性和机械强度、化学稳定性高、最好具有一定的导电性等。极性基团可以与硅表面的羟基形成氢键,增强材料之间的黏结性能,为了更好地制约硅的体积膨胀,可以对其进行改性,使其具有一定的弹性和自愈能力;也可以选择一些导电物质,使黏结剂本身具有导电性能,可以提高电极内部导电网络的稳定性并提高活性物质的含量等。本文也为黏结剂的选择和发展提供了思路。  相似文献   

11.
利用多壁纳米碳管和纳米硅材料的各自优势,分别采取涂覆法和混合法,将硅与改性多壁碳纳米管(PDCNT)复合,制备了两种新型柔性电极(Si/PDCNT和Si@PDCNT)。借助扫描电子显微技术(SEM)、能谱分析技术(EDS)和电化学技术等表征测试手段,对比分析两种新型柔性电极的形貌和电化学性能。结果表明,涂覆法制备的Si/PDCNT复合电极,纳米Si均匀分布在PDCNT柔性薄膜集流体的表面,二者结合紧密;电极循环200周,比容量保持在170 mA·h/g左右,循环性能明显优于传统的Si/Cu电极。混合法制备的Si@PDCNT柔性复合电极,纳米Si均匀地分散在碳纳米管构筑的三维导电网络结构中,电极循环500周后,比容量保持在200 mA·h/g以上,循环性能优于Si/PDCNT电极。本研究有助于推动硅基纳米碳管柔性电极的应用,为高比能量柔性电池技术的研发提供实验依据。  相似文献   

12.
The increase in energy density and power density requirements for lithium-ion secondary cells for commercial applications has led to a search for higher capacity electrode materials than those available today. Silicon would seem to be a possible alternative for the graphite or carbon anode because its intercalation capacity is the highest known. However, the large capacity fade observed during initial cycling has prevented the silicon anode from being commercialized. Here we present a review of methodologies adopted for reducing the capacity fade observed in silicon-based anodes, discuss the challenges that remain in using silicon and silicon-based anodes, and propose possible approaches for overcoming them.  相似文献   

13.
Incorporating silicon (Si) in anodes has shown great promise for the development of high capacity Li-ion batteries (LIBs). Moreover, it is a safe and environmentally benign material, and hence suitable for large-scale manufacturing. However, volumetric expansion of Si particles upon lithiation causes irreversible damage to the anode structure and promotes an unstable solid electrolyte interface (SEI), that cause a rapid capacity drop. The architecture of successful Si-based anodes, therefore, needs to cater to the large volumetric expansion such that the high specific capacity of Si can be taken advantage of without having to worry about the detrimental effects of expansion. In this study, we introduce a simple and cost-effective spray-drying method to fabricate a layered (sandwich-like) anode structure using synthesized Si nanoparticles (NPs) and thermally reduced graphene oxide (rGO). The Si NPs are obtained by the magnesiothermic reduction of SiO2 nanoparticles. Using an original, scalable, and simplistic spraying/drying method, we embedded Si NPs between two coats of strong yet flexible rGO sheets. The sandwich-like structure, which successfully contains the expansion of Si particles, protects the anode from detrimental conditions. With this new and uncomplicated production technique, the rGO-Si-rGO anode after 50 cycles, shows a high specific capacity of 1089 mAhg−1 at 1C with 97% coulombic efficiency and a stable cycling performance at current densities up to 5C.  相似文献   

14.
A new and effective approach to prepare carbon-coated Si nanocomposites as high capacity anode materials for lithium-ion batteries with markedly improved electrochemical performance is described. Initially, nanosized Si particles (<100 nm) were mixed with different concentrations of the carbon source precursor, citric acid in ethanol solution via ultrasonication. Spray pyrolysis of these mixtures at 400 °C in air resulted in an amorphous carbon coating on the spherical Si nanoparticles. High-resolution transmission electron microscopy (HRTEM) analysis confirms a homogeneous layer of amorphous carbon coating of ∼10 nm. These resultant nanocomposites show excellent cycling performance, especially when the disordered carbon (DC) content is above 50 wt.%. The 44Si/56DC nanocomposite shows the highest specific capacity retention of 1120 mAh g−1 after 100 cycles. The carbon-coating on the nanocrystalline Si particles appears to be the main reason for the good cyclability, suggesting the excellent potential of these Si/DC-based nanocomposites for use as alternative anodes for lithium-ion batteries.  相似文献   

15.
冀慧 《工业加热》2012,41(3):30-33
以FLUENT 6.3为计算平台,建立了阳极焙烧温度场的计算模型,采用数值模拟的方法研究了不同焙烧曲线对阳极升温过程、终焙温度和内外温差的影响.结果表明:数值模拟结果与实测值极为接近,所建模型具有较高的可信度.在其它参数一定的条件下,随火焰周期的延长,阳极表面和中心的升温速率变小,终焙温度升高且出现的位置后移,阳极内外温差缩小,阳极内部温度均匀性得到改善;随火焰周期的变短,阳极在各焙烧阶段的平均升温速率增大,保温时间减少,操作参数的控制难度增大.  相似文献   

16.
A new procedure for carbon anode preparation is described. First, carbon (graphite) particles are pretreated in an aqueous solution of gelatine. Then, the slurry is directly pressed on the copper substrate without addition of a special binder. It is shown that such anodes have lower irreversible loss (13–16%) than the classically prepared anodes. Efficiency reaches values close to 100% at latest in the third cycle. Reversible capacity can be as high as 340 mA h g−1. Stability of the new anodes up to 20 cycles is satisfactory only at higher concentrations of gelatine solution used in the pretreatment. Optimization of the new anode is a subject of further investigation.  相似文献   

17.
In this study, Si@Cu composite anode material is prepared by magnetron sputtering method and applied for lithium-ion batteries. The Cu component with higher intrinsic conductivity can help to improve the conductivity of the Si particles effectively. The irregularly shaped micro-sized Si particles have reduced agglomeration effect compared with nano-sized particles. In order to further relieve the volume effect of the Si particles during charging and discharging processes, carbon layer is further introduced, which will further boost the conductivity and the cyclic performance. The Si@Cu@C composite electrode exhibits a remarkably improved electrochemical performance with reversible capacity of 1130 mAhg?1 after 100 cycles with coulombic efficiency of 99.3%. The methods used for the preparation of the Si@Cu and Si@Cu@C composite materials are both mass-productive, which is benefit for their practical applications. Moreover, magnetron sputtering method used for composite power preparation has broad application prospects in micro-sized composite material preparation.  相似文献   

18.
The electrochemical performance of a composite of nano-Si powder and a pyrolytic carbon of polyvinyl chloride (PVC) with carbon nanofiber (CNF) was examined as an anode for lithium-ion batteries. CNF was incorporated into the composite by two methods; direct mixing of CNF with the nano-Si powder coated with carbon produced by pyrolysis of PVC (referred to as Si/C/CNF-1) and mixing of CNF, nano-Si powder, and PVC with subsequent firing (referred to as Si/C/CNF-2). The external Brunauer-Emmett-Teller (BET) surface area of Si/C/CNF-1 was comparable to that of Si/C/CNF-2. The micropore BET surface area of Si/C/CNF-2 (73.86 m2 g−1) was extremely higher than that of Si/C/CNF-1 (0.74 m2 g−1). The composites prepared by both methods exhibited high capacity and excellent cycling stability for lithium insertion and extraction. A capacity of more than 900 mA h g−1 was maintained after 30 cycles. The coulombic efficiency of the first cycle for Si/C/CNF-1 was as low as 53%, compared with 73% for Si/C/CNF-2. Impedance analysis of cells containing these anode materials suggested that the charge transfer resistance for Si/C/CNF-1 was not changed by cycling, but that Si/C/CNF-2 had high charge transfer resistance after cycling. A composite electrode prepared by mixing Si/C/CNF-2 and CNF exhibited a high reversible capacity at high rate, excellent cycling performance, and a high coulombic efficiency during the first lithium insertion and extraction cycles.  相似文献   

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