石墨添加对中间相炭微球电化学性能的影响

以煤焦油沥青为原料，采用聚合法制备中间相炭微球。研究了不同天然鳞片石墨添加量在相同热处理条件下得到的中间相炭微球作为锂离子电池炭负极材料的电化学性能。研究结果表明，石墨的添加使中间相炭微球内部结构变的复杂，X衍射显示石墨的添加降低了炭微球的石墨化度和晶形尺寸。随石墨添加量的增加，电池的首次充放电容量和效率有所减小，三次循环后充放电效率趋于一致。     

碳酸丙烯酯含量对中间相炭微球负极材料电化学性能的影响

碳酸丙烯酯(PC)溶剂具有极低的熔点和较高的介电常数,因此作为锂离子电池电解液溶剂,可以有效提高锂离子电池的低温性能。但由于PC易与锂离子在石墨负极表面发生共嵌入而破坏石墨结构,从而导致电池性能急剧变差。以结构稳定的中间相炭微球为负极,利用循环伏安、充放电循环测试和交流阻抗测试方法,研究了不同PC溶剂含量电解液对中间相炭微球电化学性能的影响。结果表明,中间相炭微球结构稳定,当PC含量增加到40%时仍未发生共嵌入现象。同时,随着PC含量的增加,中间相炭微球的循环性能逐步衰减。而PC含量为10%时,中间相炭微球具有最佳的循环性能,其与在不含PC溶剂的电解液中的循环性能相比,没有明显变化,循环100次后的放电比容量为207.1 m A·h/g,容量保持率为57.5%。     

中间相炭微球作为锂离子电池负极材料的研究现状

中间相炭微球（MCMB）由于具有独特的类石墨的片层结构,是一种极具发展潜力的锂离子电池负极材料,它除了具有一般炭负极材料的优点外,由于其球形层状结构还使其具有密度高、易脱嵌锂、边界损失小等特,董。本文主要论述了锂离子电池负极材料中间相炭微球的制备、热处理和改性等方面的研究现状及存在的问题;在当今锂离子电池高容量低成本的发展要求下,预期低温热处理的中间相炭微球将是今后的研究重点。     

热处理温度对锂离子电池用中间相炭微球结构及性能的影响

中间相炭微球作为一种重要的锂离子电池的负极材料,其结构直接关系到锂离子电池的充放电性能。以沥青为原料在惰性环境下,进行热缩聚反应,制备出中间相炭微球。采用XRD手段分别对炭化样品的和石墨化样品（热处理温度不同的炭微球）进行结构分析,又通过恒电流仪对他们的充放电性能进行了测试和结果比较。探讨了热处理温度对中间相炭微球结构及其性能的影响。     

成核剂对中间相炭微球性能的影响

以煤液化沥青为原料,炭黑、石油焦、石墨和针状焦为成核剂,在410℃恒温5h条件下,采用热聚合法制备中间相炭微球,并研究四种成核剂在相同热处理条件下得到的中间相炭微球,作为锂离子电池负极材料的性能.结果表明:以炭黑和石墨为成核剂可以制备得到粒度分布均匀、表面形貌较好的中间相炭微球.由电性能测试结果可知,首次可逆容量和首次效率分别为353.9mAh/g与92.9%和346.5mAh/g与92.6%.对比商品化中间相炭微球指标,发现以炭黑和石墨为成核剂制备得到的中间相炭微球,其性能与国内同类产品的性能相近.     

石墨载体对硅/炭复合负极材料性能的影响

研究了人造石墨和天然石墨2种载体对所制备的硅/炭复合负极材料电化性能的影响。结果表明:石墨载体严重影响硅/炭复合材料的首次效率、容量、循环寿命和大电流充放电性能,采用人造石墨载体制备的硅/炭复合负极材料性能明显优于天然石墨。充放电曲线表明,第一个循环由于材料未活化,存在极化,放电电压平台较低;随着循环次数的增加,在活性物质表面形成SEI膜,阻碍锂离子的脱嵌,充放电曲线电压平台差扩大;随着充放电电流密度的加大,极化就越严重,充放电曲线电压平台差就越大。     

锂离子动力电池碳负极材料研究进展

动力电池的性能是制约电动车大规模应用的重要因素,而负极材料在动力电池的生产和应用中起着关键的作用。动力型负极材料要围绕安全性、长寿命、一致性、低成本和较高的倍率充放电能力等方面进行深入系统的研究。综述了锂离子动力电池碳负极材料的研究进展,比较了中间相炭微球、石墨类与硬炭类材料的优缺点,并对提高材料高倍率充放电性能的改性方法进行了介绍。     

锂离子二次电池炭负极材料

综述了锂离子二次电池用炭负极材料:石墨、各种体系炭纤维、石墨化中间相炭微球、焦炭、热解炭的结构与电性能等特点,并通过比较选择出最适宜的炭负极材料。     

文摘

正石墨负极材料形态对LiFePO_4动力电池性能的影响[刊,中]/陈鹏,钱龙,邓昌源,等//新能源进展,2016(3):195-200分别以树脂包覆天然石墨(RCNG)、人造石墨(AG)和中间相碳微球(MCMB)为负极材料,制备了3种不同的圆柱形磷酸铁锂(LiFePO_4)动力电池。通过X射线衍射分析仪(XRD)和扫描电子显微镜(SEM)对材料的晶体结构与形貌进行表征,并采用多种手段测试了各动力电池的电化学性能。结果显示,磷酸铁锂/中间相碳微球(LFP/MCMB)电池表现     

添加石墨对中间相炭微球制备的影响

以煤焦油沥青为原料，天然鳞片石墨为添加剂，采用聚合法制备中间相炭微球。研究了天然鳞片石墨添加量对中间相炭微球形成及生长的影响，发现在相同热处理条件下，添加石墨有使微球直径减小、分布均匀的趋势。添加一定量的石墨使中问相炭微球的收率增加。     

凝胶聚合物电解质的电化学性能

用化学交联法制备了凝胶聚合物电解质.聚烯烃多孔膜支撑的凝胶聚合物电解质具有优良的电化学性能, 室温电导率为1.01×10^-3S•cm^-1,锂离子迁移数为0.41,在Al电极上的氧化起始电位达到4.2 V以上.采用聚烯烃多孔膜支撑的凝胶聚合物电解质制备了聚合物锂离子电池,并研究了工艺条件对聚合物锂离子电池电化学性能的影响.研究的工艺条件包括：单体添加量和电极组合方式.优化后的聚合物锂离子电池具有良好的电化学性能,1 C放电容量为0.2 C放电容量的93.2%,经100次1 C循环后的剩余容量仍在80%以上.     

MnO anchored reduced graphene oxide nanocomposite for high energy applications of Li-ion batteries: The insight of charge-discharge process

In the present work, a new class of anode material for high energy applications of Li-ion battery is prepared by easy and large-scale producible process. Herein, the nanocomposite of MnO and reduced graphene oxide (rGO) is prepared by anchoring MnO nanoparticles into 3D matrix of rGO hydrogel followed by annealing process. The composite which has homogeneous distribution of MnO particles on conducting rGO layers demonstrated superior electrochemical performance such as high reversible capacity, stable cycle life and better rate capability. It has shown initial discharge capacity of 2358 mAh g⁻¹ and retained 570 mAh g⁻¹ after 100 cycles as compared to pristine MnO which shown initial discharge capacity of 820 mAh g⁻¹ and retained only 45 mAh g⁻¹ after 100 cycles. The retained capacity of new MnO/rGO anode is much higher than the theoretical capacity of conventional graphite anode. Moreover, the MnO/rGO nanocomposite shows six times higher Li⁺ ion diffusion of 4.18 × 10⁻¹² cm² s⁻¹ as compared to 6.84 × 10⁻¹³ cm² s⁻¹ of MnO. In addition, the study provides insight of charge-discharge process, which conducted in initial, discharge and charge states of pristine MnO and MnO/rGO composite using ex-situ X-ray diffraction and X-ray photon spectroscopy techniques.     

应用于氧化还原电池的Fe3＋/Fe2＋电解液研究

以Fe（Ⅲ）/Fe（Ⅱ）为正极电解液的氧化还原电池,用循环伏安、交流阻抗、充放电等方法研究了在硫酸体系中的电化学行为.结果显示,Fe（Ⅲ）/Fe（Ⅱ）反应是准可逆过程,当硫酸的浓度为0.50 mol/L时,峰电流最大,Fe（Ⅱ）扩散系数Dc为2.276×10-6 cm2/s;在0.37 V下的电化学极化阻抗为2.238 Ω/cm2;与锌溶液组成电池,在20 mA/cm2进行循环充放电,充电电压在1.65 ～1.72 V,放电电压在1.11～1.25 V,电流效率为80％～97％,电压效率为65％ ～75％,能持续稳定循环110次.     

稀土元素掺杂对尖晶石型LiMn2O4正极材料的结构和电化学性能的影响

利用固相配位反应法合成稀土掺杂基锂离子电池正极材料LiMn1.995RE0.005O4(RE=Y,Nd,La),通过XRD、充放电测试等手段对材料的物相结构和电化学性能进行了研究.结果表明样品呈良好的尖晶石结构,在0.1mA/cm2和2.8-4.5V条件下恒流充放电,其首次充电容量为135mAh/g,放电容量为120mAh/g,循环可逆性好.     

Low temperature performance of graphite electrode in Li-ion cells

We studied low temperature performance of Li/graphite cell. Results show that capacity of the graphite electrode falls significantly in the temperature range of 0 to −20 °C. When lithiation and delithiation are both carried out at −20 °C, graphite only retains 12% of the room temperature capacity. However, delithiation capacity of graphite increases to 92% of the room temperature value if the lithiation is carried out at room temperature. We believe that the poor low temperature performance of the cell is due to slow kinetics of lithium ion diffusion in graphite rather than low ionic conductivity of electrolyte and solid electrolyte interface (SEI) on the graphite surface. During lithiation and delithiation processes, lithium ion has the similar apparent chemical diffusion coefficient of 10⁻⁹-10⁻¹⁰ cm²/s at 20 °C, depending on the state of lithiation of graphite. We observed a dramatic decrease in lithium ion diffusivity in the temperature range of 0 to −20 °C, and that at low temperatures of <−20 °C, lithium ion has higher diffusivity in the delithiated graphite than in the lithiated one. We also observed that temperature dependence of cycling behavior of the Li/graphite cell follows the change of lithium ion diffusivity.     

Electrochemical characteristics of copper silicide-coated graphite as an anode material of lithium secondary batteries

Copper silicide-coated graphite as an anode material was prepared by the sequential employments of plasma enhanced chemical vapor deposition (PECVD) and radio frequency magnetron sputtering (RFMS) method at 300 °C. The silicon-coated graphite exhibited an initial discharge capacity of 540 mAh/g with 76% coulomb efficiency, and the discharge capacity was sharply decreased down to 50% of initial capacity after 30 cycles, probably due to large volume changes during the charge-discharge cycling. Copper silicide-coated graphite, however, exhibited an initial discharge capacity of 480 mAh/g with higher retention capacity of 87% even after 30 cycles, probably due to the enhanced interfacial conductivity. The copper silicide film on the graphite surface played as the active anode material of lithium secondary batteries via the reduction of interfacial resistance and mitigation of volume changes during repeated cycles.     

新型AB5型氧化合金/碳复合材料作为锂离子电池负极性能研究

对回收的废旧镍氢(MH-Ni)电池负极材料AB5型储氢合金进行改性再利用,经过高温氧化处理和添加改性石墨制成复合材料后,用于高性能锂离子电池负极材料.通过X射线衍射(XBD)和电子显微镜(SEM)对材料进行了简单表征,采用恒电流充放电仪对材料进行电化学性能测试.实验结果表明,所制得的AB5型氧化合金/碳复合材料的首次充...     

Preparation and characterization of carbon cryogel (CC) and CC-SiO composite as anode material for lithium-ion battery

Carbon cryogel (CC) has been prepared through sol-gel polycondensation of resorcinol (R) with formaldehyde (F) followed by freeze-drying and carbonization in this work. The characteristics and lithium-ion insertion-extraction property have been investigated for the first time. Based on the results that CC has very excellent cycling stability but very limited lithium-ion charge-discharge capacity, SiO is employed to synthesize CC-SiO composite by high energy mechanical ball-milling to improve the applicability. The results showed that, CC-SiO is composed of active carbon, graphite, SiO and dispersed Si crystal, while CC is composed of active carbon and graphite. CC-SiO has smaller and much more uniform particles than CC. SiO can greatly improve discharge capacity of CC with an acceptable sacrifice of cycling stability, and the charge-discharge capacity of CC-SiO comes mainly from lithium insertion-extraction in Si-SiO in the sample. CC-SiO has excellent high-rate discharge ability and is promising anode material of lithium-ion battery for use of high power density purpose.     

非晶态氢氧化镍复合碳纳米管电极材料的电化学性能

采用快速冷冻化学共沉淀法制备非晶态Ni(OH)2粉体,将其作为电化学活性物质复合碳纳米管合成镍电极材料,研究了其电化学性能. 结果表明,加入碳纳米管有效减少了镍电极的电荷转移电阻,增大了电极反应过程的质子扩散系数. 复合0.5%(w)碳纳米管合成的非晶态氢氧化镍电极材料在1 C充放电制度下,放电终止电压为1.0 V时,其放电比容量高达336.5 mA×h/g,放电中值电压为1.251 V,充放电循环30次,放电比容量保持率为96.74%,表现出较好的高倍率充放电性能.