石墨烯/硫酸铅复合材料的制备及其在铅酸电池中的电化学性能

利用简单的浸渍法制备了石墨烯/硫酸铅复合材料,使得硫酸铅可以直接用作铅酸电池负极材料。该复合材料分别以100 mA.g-1、200 mA.g-1和300 mA.g-1电流密度放电时,平均放电比容量分别可达到110、94和69 mAh.g-1,而硫酸铅仅为49、5和0.5 mAh.g-1,显示出复合材料在高倍率充放电下更好的比容量和再接受充电能力。循环伏安测试表明石墨烯的电容效应随扫描速率增大而增强,同时析氢也变得严重,使得复合材料在充放电过程中充电效率比纯硫酸铅低20%。在充放电过程中,石墨烯能够提高硫酸铅1倍以上的放电容量,并将充电电压提高0.1 V。XRD和SEM结果显示硫酸铅均匀分布在石墨烯片层上,没有出现团聚现象。     

负极材料NiO的制备及电化学性能

以Ni(NO₃)₂·6H₂O和NaOH为原料,采用水热法合成了锂离子电池负极材料NiO。通过TG-DSC分析，确定了合成过程的反应机理。通过XRD、SEM和恒流充放电测试,研究了NiO样品的结构、形貌及电化学性能。400 ℃焙烧得到立方结构的NiO产品，以0.10 mA·cm^-2充放电,首次放电比容量达到1 151 mAh·g^-1，经过20次循环后的比容量仍为776 mAh·g^-1。     

微乳液法合成LiFePO4 / C正极材料及其电化学性能

本文采用微乳液方法合成了纳米LiFePO₄ / C正极材料。制备样品分别用XRD和SEM进行表征，充放电测试其电化学性能。600 ℃制备样品为单一物相，平均粒径90 nm，在室温2.0～4.0 V (vs Li) 放电电压范围和15 mA·g^-1放电速率下，首次放电容量达到159 mAh·g^-1。制备样品同样展现良好的循环性能。在15 mA·g^-1速率下40次循环后，制备样品放电容量仍保持首次放电容量的98.9%。优异的电化学性能得益于样品颗粒的纳米尺寸、均匀分布以及表面碳层包覆提高了活性材料的电子电导率。     

锂离子电池用Sn/C复合材料的碳热还原法制备

采用碳热还原法制备了Sn/C复合材料,通过XRD、SEM、恒流充放电循环、慢速扫描循环伏安(CV)等方法对材料以及其电化学嵌脱锂性能做了研究。结果表明：Sn球均匀分散在絮状碳材料中,加热时间越长,Sn球粒径越大。加热8 h得到材料的首次嵌锂比容量可达1 014 mAh·g^-1,循环15周以后的嵌锂比容量为406 mAh·g^-1。     

异质双碳源对LiMn0.8Fe0.2PO4复合材料电化学性能的影响

采用水基流变相辅助的固相法,以异质碳蔗糖和石墨为碳源,合成了LiMn_0.8Fe_0.2PO₄/C复合材料,研究了不同石墨加入方式对所制复合材料电化学性能的影响,并对所制备的LiMn_0.8Fe_0.2PO₄/C复合材料进行了X射线衍射(XRD)、N₂吸附-脱附测试、扫描电子显微镜(SEM)、透射电子显微镜(TEM)等表征。结果表明,不同石墨包覆工艺对材料结构和电化学性能具有显著影响。前驱体煅烧后再加入石墨获得的样品纯度高,形貌呈均一的椭圆形,在0.1C下的放电比容量为149 mAh·g^-1,达到其理论比容量的87%;在5C下最大的放电比容量为133 mAh·g^-1;在2C倍率下经过300次循环后比容量维持在127 mAh·g^-1,衰减率仅为1.9%,表现出了优良的循环稳定性。     

纳米CoSe修饰氮掺杂多孔碳的可控制备及其锂硫电池多硫化物的催化转化效应

锂硫电池中较差的循环稳定性和倍率性能是实现锂硫电池商业化的技术障碍,其主要原因之一是多硫化物在硫电极内的电化学转化动力学较为缓慢。为此,我们以ZIF-9为前驱体,采用先碳化,再酸化刻蚀,最后硒化的方法合成了含少量催化剂的CoSe修饰氮掺杂多孔碳(CoSe/NC)电极材料,以期提高硫电极内多硫化物的电化学转化动力学性能,并通过流动液相三电极体系对该材料进行电化学动力学表征。结果显示,相较于对比材料,CoSe/NC能够加快多硫化物的氧化还原反应速率,在 0.2mA·cm^-2电流密度下,多硫化物氧化还原反应在CoSe/NC电极上有最小的反应过电位;同时,在0.1 V过电位下,各氧化还原反应也有最大的响应电流。因此,将 CoSe/NC作为硫宿主材料组装电池展现了优异的电化学性能：在 1C(1C=1 675 mA·g^-1)下初始放电比容量为1 068 mAh·g^-1,经过500次循环后,可逆容量仍保持在693 mAh·g^-1。另外,在3C的高电流密度下,放电比容量可高达819 mAh·g^-1。     

锂离子电池正极材料LiFePO4/ C的合成研究

以三价铁化合物作为铁源，采用碳热还原法一步合成得到锂离子电池正极材料LiFePO₄。利用X射线衍射仪、扫描电镜、碳硫分析法和电化学性能测试方法对磷酸铁锂材料的物相结构、表面形貌、含碳量(质量分数)以及电性能进行分析研究。讨论了烧结温度、烧结时间和掺碳量对材料电性能的影响。结果表明，LiFePO₄的电性能与烧结温度、时间以及掺碳量有密切的关系，在优化试验条件下制备的正极材料LiFePO₄，以电流密度为17 mA·g^-1充放电，首次放电容量达到141.8 mAh·g^-1，80次循环后放电容量为137.7 mAh·g^-1，容量保持率为97.1%。     

Sn-SnSb/石墨复合材料的制备及电化学性能

以柠檬酸钠为配位剂、NaBH4为还原剂，将Sn(Ⅱ)和Sb(Ⅲ)盐在水溶液中共还原制得Sn-SnSb合金。X射线衍射和扫描电镜的测试结果表明：所得合金为多相合金，颗粒大小约200 nm。将该合金粉和石墨按质量比4∶1经机械球磨形成Sn-SnSb/石墨复合材料，将其作为锂离子电池阳极材料进行电化学性能测试，结果表明，该复合材料可逆容量超过600 mAh·g^-1，具有良好的循环性能，15次循环内的稳定比容量为461 mAh·g^-1，而纯Sn-SnSb合金粉15次循环后充电比容量为337 mAh·g^-1。     

钽离子掺杂对LiFePO4 / C物理和电化学性能的影响

采用PAM(聚丙烯酰胺)模板-溶胶凝胶法在惰性气氛下合成钽掺杂的LiFePO₄/C复合正极材料，考察了钽对目标化合物的物理和电化学性能的影响。研究结果表明，0.33C的电流下充放电时，掺杂前后第2个循环的放电容量分别为138.6 mAh·g^-1和155.5 mAh·g^-1，循环20次后容量为141 mAh·g^-1和156 mAh·g^-1。电化学交流阻抗表明，掺杂后的材料阻抗R_ct从180 Ω减小到120 Ω。振实密度比掺杂前提高0.312 g·cm^-3。     

非晶态Fe-P合金电极的电沉积制备及其储锂性能

应用电沉积技术制备了Fe-P合金电极材料。采用X射线衍射(XRD)和扫描电子显微镜(SEM)分析了该合金材料的相结构和表面形貌。XRD分析结果表明电沉积的Fe-P合金具有非晶态结构。电化学性能测试表明：平面结构的Fe-P合金电极首次放电(脱锂)容量达542 mAh·g^-1,首次循环的库仑效率为60%;50周循环之后放电容量为366 mAh·g^-1。用非原位的XRD和SEM对电极的充放电机理进行了初步研究,结果表明,首次充电(嵌锂)过程中形成Li₃P相,电极表面生成纳米棒结构铁-磷合金,它能有效缓解锂嵌入/脱出时引起的合金结构变化,抑制合金材料的体积膨胀,从而提高该合金电极的充放电效率和循环性能。     

Lead sulfate used as the positive active material of lead acid batteries

Lead sulfate is produced when a lead acid battery discharges, and it is also known that big PbSO₄ crystals are less active than the smaller ones because they dissolve slower, thus result in failure of the battery. However, little is known if chemically prepared PbSO₄ can be used as active material of lead acid batteries. Here, we report the preparation of PbSO₄ by facile chemical precipitation of aqueous lead acetate with sodium sulfate and its utilization as the positive active material. The results show that the PbSO₄ alone is not good enough for the purpose, but its mixtures with Pb₃O₄ are as excellent as the industrial leady oxide. For example, the mixtures containing 5, 10, 20, and 30 wt.% of Pb₃O₄ discharge 78.2, 92.9, 88.0, and 91.5 mAh g^?1 at a current density of 100 mA g^?1, respectively. Also, the one with 10 % Pb₃O₄ remains 93 % capacity in 150, 100 % DOD cycles.     

Interlayer-expanded MoS<Subscript>2</Subscript>/graphene composites as anode materials for high-performance lithium-ion batteries

A facile strategy was developed to prepare interlayer-expanded MoS₂/graphene composites through a one-step hydrothermal reaction method. MoS₂ nanosheets with several-layer thickness were observed to uniformly grow on the surface of graphene sheets. And the interlayer spacing of MoS₂ in the composites was determined to expand to 0.95 nm by ammonium ions intercalation. The MoS₂/graphene composites show excellent lithium storage performance as anode materials for Li-ion batteries. Through gathering advantages including expanded interlayers, several-layer thickness, and composited graphene, the composites exhibit reversible capacity of 1030.6 mAh g^?1 at the current density of 100 mA g^?1 and still retain a high specific capacity of 725.7 mAh g^?1 at a higher current density of 1000 mA g^?1 after 50 cycles.     

Electrochemical property of α-PbO prepared from the spent negative powders of lead acid batteries

To make full and economic use of the spent lead acid batteries (LABs), we have invented a novel route to separate their negative electrode material from positive one, which are respectively used to fabricate α-PbO for new LABs. This paper reports preparation and electrochemical property of α-PbO from the spent negative material which is compose of PbSO₄ (the major phase) and Pb (the minor phase). To make things simpler, pure PbSO₄ is firstly used as the model compound and desulfated with (NH₄)₂CO₃ to obtain PbCO₃, which is then calcined in air at different temperatures to produce PbO. At 450 °C, the calcination produces pure α-PbO that discharges a capacity of 98.6 mAh g^?1 at the current density of 120 mA g^?1 after 50 charging and discharging cycles of 100 % DOD. By using the same procedures, the real spent negative powder is also treated to produce pure α-PbO, which discharges a similar capacity of 100 mAh g^?1 at 120 mA g^?1. This is 25 % higher than that of industrial leady oxide. These results show that the small amount of metallic lead has little effect on the treatment.     

Capacity of graphene anode in ionic liquid electrolyte

The graphene anode was investigated in an ionic liquid electrolyte (0.7 M lithium bis(trifluoromethanesulfonyl)imide (LiNTf₂)) in room temperature ionic liquid (N-methyl-N-propylpyrrolidinium bis(trifluoromethanesulfonyl)imide (MPPyrNTf₂)). SEM and TEM images suggested that the electrochemical intercalation/deintercalation process in the ionic liquid electrolyte without vinylene carbonate (VC) leads to small changes on the surface of graphene particles. However, a similar process in the presence of VC results in the formation of a coating (SEI—solid electrolyte interface) on the graphene surface. During charging/discharging tests, the graphene electrode working together with the 0.7 M LiNTf₂ in MPPyrNTf₂ electrolyte lost its capacity, during cycling and stabilizes at ca. 200 mAh g^?1 after 20 cycles. The addition of VC to the electrolyte (0.7 M LiNTf₂ in MPPyrNTf₂?+?10 wt.% VC) considerably increases the anode capacity. Electrodes were tested at different current regimes: ranging between 50 and 1,000 mA g^?1. The capacity of the anode, working at a low current regime of 50 mA g^?1, was ca. 1,250 mAh g^?1, while the current of 500 mA g^?1 resulted in capacity of 350 mAh g^?1. Coulombic efficiency was stable and close to 95 % during ca. 250 cycles. The exchange current density, obtained from impedance spectroscopy, was 1.3?×?10^?7 A cm^?2 (at 298 K). The effect of the anode capacity decrease with increasing current rate was interpreted as the result of kinetic limits of the electrode operation.     

Facile synthesis of CoWO<Subscript>4</Subscript>/RGO composites as superior anode materials for lithium-ion batteries

In this paper, a facile method has been developed to synthesize supported CoWO₄ on the reduced graphene oxide (RGO) as high-performance anode material for Li-ion batteries. The composites with cuboid-like CoWO₄ nanoparticles were prepared by directly adding graphene oxide into the precursor solution followed by a hydrothermal treatment. Different analytical methods like high-resolution TEM, XRD, TGA, and XPS characterizations were employed to illustrate structural information of the as-prepared CoWO₄ and CoWO₄/RGO composites. In addition, the Li-ion battery performance using the composites as anode materials was also discussed based on the detailed galvanostatic charge-discharge cycling tests. The result shows that the specific capacity of the as-prepared CoWO₄/RGO composites can reach 533.3 mAh g^?1 after 50 cycles at a current density of 100 mA g^?1. During the whole cyclic process, the coulombic efficiency was maintained higher than 90%. Therefore, CoWO₄, as an environment-friendly and cost-effective anode material, has promising potential for Li-ion batteries.     

Fabrication of Porous Nitrogen‐Doped Carbon Materials as Anodes for High‐Performance Lithium Ion Batteries

The hierarchical porous nitrogen‐doped carbon materials (HNCs) were prepared by using nitrogen containing gelatin as the carbon source and nano‐silica obtained by a simple flame synthesis approach as the template. All of the as‐obtained HNCs show much higher Li storage capacity as compared with commercial graphite. Specifically, HNC‐700 with biggest micropore volume and highest nitrogen content exhibited optimal reversible capacities of 1084 mAh·g^??1 at the current density of 37.2 mA·g^?1 (0.1 C) and 309 mAh·g^?1 even at 3.72 A·g^?1 (10 C). This result suggests that HNCs should be a promising candidate for anode materials in high‐rate lithium ion batteries (LIBs).     

溶胶凝胶法合成富锂正极材料Li[Li0.2Ni0.2Mn0.6]O2及性能表征

以LiOH.H2O、Mn(CH3COO)2.4H2O和Ni(CH3COO)2.4H2O为原料,分别用柠檬酸(CA)与乙二胺四乙酸(EDTA)为配位剂,采用溶胶凝胶法结合固相烧结法制备富锂固溶体正极材料Li[Li0.2Ni0.2Mn0.6]O2。通过X射线衍射(XRD)、扫描电子显微镜(SEM)、激光粒度仪对所得样品的结构、形貌、粒径分布进行了表征,并测试了材料的电化学性能。采用CA配位制备的材料的电化学性能优于用EDTA配位制备的材料的电化学性能,室温下以18 mA.g-1的电流密度,在2.0~4.8 V电压范围内充放电,用CA制备的材料首次充电比容量高达324 mAh.g-1,首次库伦效率达82%;在180 mA.g-1的电流下,其可逆比容量保持在120 mAh.g-1。