Anthraquinone derivative as high-performance anode material for sodium-ion batteries using ether-based electrolytes

Organic materials, especially the carbonyl compounds, are promising anode materials for room temperature sodium-ion batteries owing to their high reversible capacity, structural diversity as well as eco-friendly synthesis from bio-mass. Herein, we report a novel anthraquinone derivative, C_(14)H_6 O_4 Na_2 composited with carbon nanotube(C_(14)H_6 O_4 Na_2-CNT), used as an anode material for sodium-ion batteries in etherbased electrolyte. The C_(14)H_6 O_4 Na_2-CNT electrode delivers a reversible capacity of 173 mAh g^(-1) and an ultra-high initial Coulombic efficiency of 98% at the rate of 0.1 C. The capacity retention is 82% after 50 cycles at 0.2 C and a good rate capability is displayed at 2 C.Furthermore, the average Na insertion voltage of 1.27 V vs. Na^+/Na makes it a unique and safety battery material, which would avoid Na plating and formation of solid electrolyte interface. Our contribution provides new insights for designing developed organic anode materials with high initial Coulombic efficiency and improved safety capability for sodium-ion batteries.

Facile Fabrication of Fe3O4@TiO2@C Yolk–Shell Spheres as Anode Material for Lithium Ion Batteries

Transition metal oxides have been actively exploited for application in lithium ion batteries due to their facile synthesis,high specific capacity,and environmental-friendly.In this paper,Fe3O4@TiO2@C yolk-shell(Y-S)spheres,used as anode material for lithium ion batteries,were successfully fabricated by Stober method.XRD patterns reveal that Fe3O4@TiO2@C Y-S spheres possess a good crystallinity.But the diffraction peaks’intensity of Fe3O4 crystals in the composites is much weaker than that of bare Fe3O4 spheres,indicating that the outer anatase TiO2@C layer can cover up the diffraction peaks of inner Fe3O4 spheres.The yolk-shell structure of Fe3O4@TiO2@C spheres is further characterized by TEM,HAADFSTEM,and EDS mapping.The yolk-shell structure is good for improving the cycling stability of the inner Fe3O4 spheres during lithium ions insertion-extraction processes.When tested at 200 mA/g,the Fe3O4@TiO2@C Y-S spheres can provide a stable discharge capacity of 450 mAh/g over 100 cycles,which is much better than that of bare Fe3O4 spheres and TiO2@C spheres.Furthermore,cyclic voltammetry curves show that the composites have a good cycling stability compared to bare Fe3O4 spheres.

Fabrication,characterization and electrochemical properties of porous coral-structured Si/C composite anode for lithium ion battery

A porous coral-structured Si/C composite as an anode material was fabricated by coating Si nanoparticles with a carbon layer from polyvinyl alcohol（PVA）, erosion of hydrofluoric（HF） acid, and secondary coating with pitch. Three samples with different pitch contents of 30%, 40% and 50% were synthesized. The composition and morphology of the composites were characterized by X-ray diffractometry（XRD） and scanning electron microscopy（SEM）, respectively, and the properties were tested by electrochemical measurements. The results indicated that the composites showed obviously enhanced electrochemical performance compared with that without secondary carbon coating. The second discharge capacity of the composite was 773 m A·h/g at a current density of 100 m A/g, and still retained 669 m A·h/g after 60 cycles with a small capacity fade of less than 0.23%/cycle, while the content of secondary carbon source of pitch was set at 40%. Therefore, the cycle stability of the composite could be excellently improved by regulating carbon content of secondary coating.

SnS_2@C Hollow Nanospheres with Robust Structural Stability as High?Performance Anodes for Sodium Ion Batteries

Constructing unique and highly stable structures with plenty of electroactive sites in sodium storage materials is a key factor for achieving improved electrochemical properties through favorable sodium ion di usion kinetics. An SnS_2@carbon hollow nanospheres(SnS_2@C) has been designed and fabricated via a facile solvothermal route, followed by an annealing treatment. The SnS_2@C hybrid possesses an ideal hollow structure, rich active sites, a large electrode/electrolyte interface, a shortened ion transport pathway, and, importantly, a bu er space for volume change, generated from the repeated insertion/extraction of sodium ions. These merits lead to the significant reinforcement of structural integrity during electrochemical reactions and the improvement in sodium storage properties, with a high specific reversible capacity of 626.8 mAh g^(-1) after 200 cycles at a current density of 0.2 A g^(-1) and superior high-rate performance(304.4 mAh g^(-1) at 5 A g^(-1)).

水热-碳热还原原位合成锂离子电池Sn-Co-C复合负极材料

以纳米二氧化锡、硝酸钴、脲、葡萄糖和十二烷基硫酸钠为原料,通过水热-碳热还原原位制备锂离子电池Sn-Co-C复合负极材料。通过XRD、SEM、EDS和TEM分析表明,原位生成的Sn-Co合金颗粒分布于纳米或微米尺度的碳球和碳纳米棒内部以及微孔碳基体之中。电化学测试表明,在50 m A·g-1电流密度下,Sn-Co-C复合负极材料首次充放电比容量分别为602.9 m Ah·g-1和867.1 m Ah·g-1,循环100次后其充放电比容量仍分别保持在350.4 m Ah·g-1和356.6 m Ah·g-1,平均每次放电容量衰减率仅为5.1%。优异的电化学性能主要归因于Sn-Co合金颗粒处于纳米或微米尺度的碳球和碳纳米棒内部以及微孔碳基体之中可以改善其导电性,并可以缓解锂电池充放电过程中产生的体积变化所导致的活性物质脱落,提高循环性能和寿命。

锂离子电池Sn-Co-C复合材料的制备及性能

以金属锡粉(Sn)、金属钴粉(Co)和乙炔黑为主要原料,综合利用固相烧结和高能球磨的方法制备出Sn-Co-C复合负极材料,采用XRD、SEM、EDS和恒电流充放电等技术对材料进行了表征和电性能测试.实验结果表明:高能球磨处理后,Sn-Co-C复合材料颗粒尺寸减小,首次放电容量显著提升,为476.8 m Ah/g;经过30次循环后可逆容量仍保持在394.4 m Ah/g.

C/Sn复合薄膜的磁控溅射制备及其作为锂离子电池负极材料的电化学性能

采用磁控溅射的方法在铜箔上制备了C/Sn复合薄膜并将其作为锂离子电池负极材料,研究了C/Sn复合薄膜中Sn质量分数对其电化学性能的影响。研究发现,随着复合薄膜中Sn质量分数的增加,其首圈放电比容量增加,在一定范围内增加Sn质量分数,首圈库仑效率增加,但当Sn质量分数过多时其库仑效率降低。Sn质量分数分别为89.20%、91.61%、93.85%、95.81%的四种复合薄膜,在电流密度为500 mA/g时的首圈放电比容量分别为1195.4、1372.97、1574.86、1642.30 mA·h/g,首圈库仑效率分别为86.84%、87.88%、94.06%、80.66%。循环200圈后,四种复合薄膜的比容量衰减率分别为0.70%、6.13%、11.32%、18.88%。研究结果表明,当复合薄膜中Sn质量分数为89.20%时,其具有最优的倍率性能和循环稳定性能,随着复合薄膜中Sn质量分数的增加,其倍率性能及循环稳定性变差。

锂离子电池Sn-Co/C负极材料的制备与性能

采用高温碳化裂解技术和高能球磨处理制备了改性的高容量Sn-Co/C负极复合材料.采用XRD、SEM、恒电流充放电和交流阻抗等技术对材料进行了表征和电话线性能测试.结果表明,高能球磨处理后,Sn-Co/C出现非晶、纳米晶的混合组织.电极的首次放电和充电容量分别为1 098.9和771.3 mAh/g,经100次循环后可逆容量仍保持在425.1 mAh/g.稳定后平均容量衰减率为0.18%.改性的Sn-Co/C具有更高的锂离子扩散系数,提高了合金材料的充放电性能.

蛋黄-壳NiCoP@N-C材料的制备及其储钠特性研究

NiCo基磷化物因其优异的导电性和较高的理论容量,被认为是最有潜力的钠离子电极材料.然而,NiCo基磷化物在钠离子嵌入/脱出时会发生严重的体积应变,导致NiCo基磷化物的倍率特性降低,循环稳定性大幅度衰减.针对这些问题,采用多巴胺包覆-煅烧-磷化处理法制备了蛋黄-壳结构的NiCoP@N-C材料,在该材料中,氮掺杂碳层有效地改善了电极材料固有的电导率和结构完整性;独特的蛋黄-壳结构显著减缓了在钠离子嵌入/脱出过程中的体积膨胀.当NiCoP@N-C作为钠离子电池负极材料时表现出优异的电化学性能.在0.1 A·g^(-1)电流密度下,循环100圈后的可逆比容量仍高达462.3 mAh·g^(-1).

Cobalt phosphide nanoparticles embedded in nitrogendoped carbon nanosheets： Promising anode material with high rate capability and long cycle life for sodiumion batteries

Cobalt phosphide （COP） nanoparticles which were uniformly embedded in N-doped C nanosheets （CNSs） were fabricated via the simple one-step calcination of a Co-based metal-organic framework （MOF） and red P and exhibited a high capacity, fast kinetics, and a long cycle life. This CoP/CNS composite contained small CoP particles （approximately 11.3 nm） and P-C bonds. When its electrochemical properties were evaluated by testing CoP/Na coin cells, the composite delivered a Na-storage capacity of 598 mAh·g-1 at 0.1 A·g-1 according to the total mass of the composite, which means that the capacity of pure CoP reached 831 mAh·g-1 The composite also exhibited a high rate capability and long-term cyclability （174 mAh·g-1 at 20 A·g-1 and 98.5% capacity retention after 900 cycles at 1 A·g-1）, which are commonly attributed to robust P-C bonding and highly conductive CNSs. When the reaction mechanism of the CoP/CNS composite was investigated, a conversion reaction expressed as CoP ＋ 3Na＋ ＋ 3e＋＋ Co ＋ Na3P was observed. The outstanding Na-storage properties of the CoP/CNS composite may suggest a new strategy for developing high-performance anode materials for Na-ion batteries.

High-performance SiO/C as anode materials for lithium-ion batteries using commercial SiO and glucose as raw materials

Silicon monoxide(SiO)is considered as a promising anode material for lithium-ion batteries(LIBs)due to its higher capacity and longer cycle life than those of graphite and silicon,respectively.In this study,glucose was developed as a suitable and inexpensive carbon source to synthesize SiO/C composite with a high performance.In addition,the effects of the calcination temperature and the amount of c arbon source on the electrochemical performance of the SiO/C composite were investigated.The addition of 5 wt%glucose and a calcination temperature of 800℃ demonstrated the optimum conditions for SiO/C synthesis.The resultant SiO/C showed an initial charge capacity of 1259 mAh·g^(-1) and a high initial coulombic efficiency of 71.9%.A charge capacity of 850 mAh·g^(-1) after 100 cycles at 200 mA·g^(-1) was achieved,demonstrating the best value of the SiO/C-based materials.The composition changes of SiO under the calcination temperature played a significant role in the electrochemical performance.Overall,the obtained SiO/C material with a high capacity and good stability is suitable for LIB applications as an anode material.

Bimetallic Sulfide/Sulfur Doped T3C2TA:MXene Nanocomposites as High-performance Anode Materials for Sodium-ion Batteries

The application of transition metal dichalcogenides(TMDs)as anode materials in sodium-ion batteries(SIBs) has been hindered by low conductivity and poor cyclability.Herein,we report the synthesis of CoxFe1-xS2 bimetallic sulfide/sulfur-doped Ti3C2 MXene nanocomposites(CoxFe1-xS2@S-Ti3C2)by a facile co-precipitation process and thermal-sulfurization reaction.The interconnected 3D frameworks consisting of MXene nanosheets can effectively buffer the volume change and enhance the charge transfer.In particular,sulfur-doped MXene nanosheets provide rich active sites for sodium storage and restrain sulfur loss during charging/discharging processes,leading the increase of specific capacity and cycling the stability of anode materials.As a result,CoxFe1-xS2@S-Ti3C2 anodes exhibited high capacity,high rate capability and long cycle life(399mA·h/g at 5A/g with an 94% capacity retention after 600 cycles).

锂离子电池Si/C/石墨复合负极材料的电化学性能

采用热裂解方法,热解分散于聚偏二氟乙烯溶液中的硅和石墨,得到了具有稳定电化学循环性能的Si/C/石墨复合负极材料。透射电子显微镜观察发现,复合材料形貌为无定型碳包裹硅颗粒的核壳结构。通过系统研究不同Si粒径和石墨含量对电极电化学性能的影响,发现Si颗粒粒径越小复合材料电化学循环稳定性能越优越,适当的降低石墨含量有利于电极材料剩余比容量的提高。当Si粒径为50 nm,Si与石墨质量比1:1时,电极材料具有1741.6 mAh/g的首次放电比容量和72.5%的首次库仑效率,60次循环后,可逆比容量保持在820 mAh/g。热解有机物形成碳包覆的结构能有效地改善硅基类负极材料的电化学循环性能。

镁离子掺杂对Li_4Ti_5O_(12)/C结构和电化学性能的影响

以乳酸镁为Mg2+的掺杂源和部分碳源,以乙醇为溶剂,在惰性气氛下采用高温固相合成法合成掺Mg2+的Li4Ti5O12/C复合材料。采用X-射线衍射、扫描电子显微镜、激光粒度分析和电性能测试等对复合材料进行表征,考察了Mg2+对于目标化合物结构和电化学性能的影响。结果表明,在C/3倍率下材料掺杂前后第二个循环的放电容量分别为145、162 mAh/g,循环30次后容量为138、150 mAh/g。电化学交流阻抗表明,掺杂后的材料阻抗Rct从180Ω减小到45Ω。掺杂后振实密度比掺杂前提高了0.27 g/cm3。

Sn/C复合材料的制备及其电化学性能

以煤焦油沥青为碳源、三丁基氯化锡(TBTC)为锡源,采用压力下聚合手段原位合成出Sn/C复合材料,并对它的电化学性能进行了研究。通过SEM、XRD、恒电流充放电测试等手段研究了不同Sn含量的Sn/C复合材料的形态、结构及其电化学行为,结果表明TBTC对沥青的热缩聚反应有显著的催化作用,热聚产物中吡啶不溶物(PI)组分的含量由未添加时的35.5%逐渐提高至添加量为25%时的60.3%;进一步热处理后,Sn/C复合材料中的锡由原来的SnS转化为金属锡的形式存在;其首次循环效率随着热处理温度的提高而增加,而首次充放电容量随着TBTC添加量的增加先增加后减少,在10%时达到最大的比容量值,首次充放电容量分别为674mAh/g和465mAh/g,第二次循环后,循环效率达到95%以上,是一种性能较佳的锂离子蓄电池负极材料。

锂离子电池Si/C复合负极材料的合成与性能

采用球磨-热解工艺制备了Si/C复合负极材料。研究了球磨时间对Si/C复合负极材料结构和电化学性能的影响,并分析了电极的失效机理。研究结果表明,通过球磨可以将纳米硅颗粒均匀分散于石墨基体材料表面,同时,葡萄糖热解后形成的无定形碳使两者紧密结合。球磨3h合成的材料具有最优的电化学性能。以100mA/g的电流密度放电,首次放电容量达到1340mAh/g,首次充放电效率为75.6%,循环50次后,容量保持率为34.2%。

锂离子电池Si-Mn／C负极材料的电化学性能

利用机械球磨法得到Si和Mn原子比为3:5的复合材料,将此材料与20 wt％的石墨混合球磨得到Si3Mn5／C复合材料．利用X射线衍射(XRD)和扫描电子显微镜(SEM)分析材料的物相和电极的微观结构．结果表明:所得材料中没有Si-Mn二元新相的生成,材料的颗粒尺寸为0．5—2．0μm．碳的加入抑制了活性中心Si在循环过程中的较大结构变化,且Si—Mn复合物颗粒均匀地分散在碳的网格中,增加了复合材料的电接触．合成样品的电化学测试表明, 石墨的添加提高了Si-Mn复合材料的可逆容量和循环性能． Si-Mn／C复合物的首次可逆容量为347mAh·g-1,充放电效率为70％．进而经200℃热处理的Si-Mn／C电极的首次可逆容量为 463mAh·g-1,充放电效率为70％．在30个循环后复合材料仍保持426mAh·g-1的可逆容量, 充放电效率稳定在97％以上．

BaFeSi/C复合物作为锂离子电池负极材料的研究

采用机械球磨法制备BaFeSi/C复合物,并考察了其作为锂离子电池负极材料的电化学性能.结果表明,这种复合材料具有较高的初始放电容量、合适的充放电平台和良好的循环可逆性.XRD和XPS研究证明:BaFeSi/C复合物循环性能的提高主要源于惰性导电组分FeSi2、BaSi2和外层石墨骨架的协同作用,它们的存在不仅有效地缓冲了活性组分硅的体积变化,同时在很大程度上增强了复合材料的电子导电性和离子导电性.

SiO/C复合材料在锂离子电池中的应用

硅基负极材料因其较高的比容量而受到研究者广泛的关注。本文选取高比容量SiO_x与NG复合材料作为锂离子电池负极材料,研究了不同SiO/C复合比例对全电池的能量密度和循环性能的影响。不同比例SiO_x/C复合材料的首次容量和首次效率有明显差别。与石墨材料相比,SiO_x/C复合材料的膨胀程度略有增加。随着SiO_x比例的增加,全电池的能量密度先是上升然后下降,但其循环稳定性却有所降低。当SiO_x比例在4%时,全电池能量密度提升4.2%,500周循环后容量保持率在80%以上,可以满足商业化锂离子电池的使用要求。

纳米SnS/C复合物作为锂电池负极材料的研究

采用高能球磨法制备了纳米SnS/C复合材料,通过XRD、SEM和TEM等结构和形貌实验表明可以通过高能球磨法直接合成SnS纳米颗粒,并实现碳的均匀包覆。恒流充放电实验显示SnS/C复合材料的可逆比容量为1 107m Ah/g,达到理论比容量的97.4%,基本实现可逆的转化反应和合金化反应。这种材料在800 mA/g的电流密度下仍能达到854 m Ah/g的可逆比容量,显示了高的倍率性能。这些优异的电化学性能主要由于通过电化学还原反应生成的纳米Sn具有高的电化学活性。以及生成物Li2S的隔离作用和导电碳网络的缓冲作用,有利于保持材料结构的稳定和电化学反应的可逆进行。这种高性能纳米SnS/C复合材料为高比能锂离子电池的发展提供了可选体系。