ZnMn2O4/Mn2O3/CNT复合正极材料的制备及其在水锌离子电池中的应用

以Zn(NO3)2·6H2O、Mn(AcO)2·4H2O和碳纳米管(CNT)为原料,经过表面活性剂辅助溶剂热反应合成了CNT包覆ZnMn2O4/Mn2O3(ZMO/MO)复合材料,通过XRD和SEM对材料的结构和形貌进行表征.结果表明,CNT均匀包覆在微球状ZMO/MO复合物的表面.在0.1 A/g电流密度下,CNT包覆量为10％(即CNT质量占复合微球质量的百分数,下同)的ZMO/MO/10CNT复合材料放电比容量为112.8 mA·h/g,并且在300次循环后仍能保持在49.6 mA·h/g的可逆比容量.在电流密度为0.1、0.2、0.4、0.8、1.2、2.0 A/g时,其放电比容量分别为126.2、124.4、115.4、94.2、57.3和45.0 mA·h/g.采用循环伏安曲线和电化学阻抗探究了电极的动力学特性,两相复合提高了Zn2+扩散速率,CNT的包覆改善了材料的电荷传递.     

MgF2包覆对正极材料LiNi1/3Co1/3Mn1/3O2性能的影响

通过浸渍法在正极材料LiNi1/3Co1/3Mn1/3O2的表面包覆MgF2,通过XRD、SEM、交流阻抗（EIS）分析、充放电测试研究了不同量MgF2包覆对LiNi1/3Co1/3Mn1/3O2正极材料的结构与电化学性能的影响。结果表明,MgF2以非晶态形式包覆于LiNi1/3Co1/3Mn1/3O2材料颗粒的表面,当包覆量为3%（物质的量分数,下同）时,三元正极材料具有优良的电化学性能,在3.0~4.6 V充放电范围内0.1C充放电倍率下,首次放电比容量为196.3 mA·h/g,1C循环50次后容量保持率为95.7%,55 ℃高温下1C循环50次后容量保持率为93.3%。     

ZrO2包覆对层状氧化物正极材料储钠性能的改善

层状氧化物正极材料具有良好的结构稳定性和较高的充放电比容量,是一类理想的钠离子电池正极材料。本工作研究了层状氧化物正极材料NaNi1/3Fe1/3Mn1/3O2表面修饰对其电化学性能的影响,采用固相球磨法在正极材料表面包覆一层纳米ZrO2,采用形貌、结构、电化学方法等研究了包覆后性能改进机理。研究结果表明,ZrO2在NaNi1/3Fe1/3Mn1/3O2表面形成一层惰性保护层,有效隔开了电解液与正极材料的接触,缓解了电解液的分解速度,抑制了金属离子的溶出速度,从而显著改善了电池的循环性能以及高温性能。在ZrO2包覆修饰后,55℃下正极材料相比于未包覆的正极材料有明显提升,100次循环后容量保持率达到83.6%,高于未包覆的75.2%。此外,包覆后的NaNi1/3Fe1/3Mn1/3O2正极材料在空气环境存储后,稳定性得到明显提高。     

Li(Ni-Co-Al)O_2三元材料制备及其超级电容性能研究

三元正极材料Li(Ni-Co-Al)O2因其良好的电化学性能已经逐渐发展为替代其他传统三元正极材料的新型电极材料。本文以氨水做络合剂、氢氧化钠为沉淀剂,采用共沉淀-固相法制备Li(Ni-Co-Al)O2三元材料并用于超级电容器件研究,探究了Li(Ni-Co-Al)O2的制备条件和氧化铝包覆改性对材料超级电容性能的影响。通过X射线衍射、比表面积的表征研究制备条件对Li(Ni-CoAl)O2物化性质的影响,通过循环伏安、恒流充放电、循环倍率以及交流阻抗等电化学性能测试探究了材料的超级电容性能的影响。结果表明:采用共沉淀-固相法制备的三元Li(Ni-Co-Al)O2材料具有良好的比电容,且通过氧化铝包覆改性后材料的比电容和循环稳定性都得到了进一步的提升。     

高性能低镍三元正极复合材料LiNi1/3Co1/3Mn1/3O2/V2O5的表面活性剂辅助水热法制备及其电化学性能研究

采用表面活性剂辅助水热法制备出LiNi1/3Co1/3Mn1/3O2/V2O5三元正极复合材料,探讨了该复合材料形貌、结构并研究了其电化学性能.实验结果表明,使用十二烷基苯磺酸钠(SDBS)作为表面活性剂,用1％V2O5对材料进行包覆,获得了均匀、紧密的复合材料颗粒.在2.5～4.6 V电压、0.5 C放电倍率条件下,首次放电量达到201.516 mAh/g,容量保持率高,具备良好的循环稳定性与倍率性能.表明所制备的LiNi1/3Co1/3Mn1/3O2/V2O5三元正极复合材料具有良好的电化学性能.     

Li2ZrO3包覆LiNi0.8Co0.1Mn0.1O2的复合材料及其电化学性能

以Zr（NO₃）₄·5H₂O和CH₃COOLi·2H₂O为原料,采用湿化学法,将Li₂ZrO₃包覆在LiNi_0.8Co_0.1Mn_0.1O₂锂离子电池正极材料的表面,研究Li₂ZrO₃不同包覆比例对LiNi_0.8Co_0.1Mn_0.1O₂电化学性能的影响。SEM、TEM、EDS谱图分析表明,Li₂ZrO₃层均匀地包覆在LiNi_0.8Co_0.1Mn_0.1O₂表面,其厚度约为8 nm。与纯相相比,1%（质量分数） Li₂ZrO₃包覆的LiNi_0.8Co_0.1Mn_0.1O₂复合材料在1.0 C下首次放电比容量为184.7 mA·h·g^-1、100次循环之后放电比容量为169.5 mA·h·g^-1,其容量保持率达到91.77%,表现出良好的循环稳定性。循环伏安（CV）和电化学阻抗（EIS）测试结果表明,Li₂ZrO₃包覆层抑制了正极材料与电解液之间的副反应,减小了材料在循环过程中的电荷转移阻抗,从而提高了材料的电化学性能。     

Co3O4/碳纳米管复合膜的超级电容器性能

采用电泳沉积法在镍片上沉积Co3O4/碳纳米管(CNT)复合膜。利用XRD、SEM和TEM对Co3O4/CNT复合膜进行物性分析,利用循环伏安和恒流充放电测试表征电容性能。研究表明在CNT表面成功包覆了一层Co3O4壳层,形成独特的核/鞘纳米电缆结构。电化学测试表明,Co3O4/CNT复合膜电极具有较好的电容性能,在充放电电流密度为0.5 mA/cm^2时,比电容高达282 F/g;增加电流密度到15 mA/cm2时,比电容为209 F/g,并具有优异的循环稳定性。     

0.7Li2MnO3-0.3LiNi1/2Mn1/2O2的共沉淀制备及电化学性能

本文通过共沉淀法合成了0.7Li2MnO3-0.3LiNi1/2Mn1/2O2这种正极材料,并对这种材料的结构、相组成和微观形貌进行了表征,并且进行了电化学性能测试。结果表明这种电极材料在循环测试中比容量能达到100mAh.g-1,后续循环稳定性较好。     

多晶型MnO2改善富锂锰基正极材料的电化学性能

富锂锰基正极材料由于具有较高的理论比容量,被认为是下一代锂电池最有前途的正极材料之一。但在循环过程中存在比容量低、倍率性能差、衰减速度快等问题。基于此,本文采用水热法制备了多晶型MnO₂材料,并利用湿化学研磨法结合热处理工艺对商业富锂锰基正极材料进行了表面包覆改性。通过循环伏安、恒流充放电及电化学阻抗谱对所得材料进行电化学性能测试,并通过包覆前后材料电化学性能的变化研究了多晶型MnO₂对富锂锰基正极材料电化学性能的影响。结果表明,β-MnO₂的电化学性能最佳,其初始比容量在0.1 C下达到292.2 mAh·g^-1,在0.1～5.0 C的倍率下容量保持率为56.3%,在1 C下循环50次后容量保持率为81.6%。通过EIS测试得出β-MnO₂的包覆改善了原样品电化学反应过程中的电化学动力学。     

碳纳米管作为导电添加剂的锂电池阴极材料LiCoO2的性能研究

使用碳纳米管(CNT)作为锂电池阴极材料LiCoO2的导电添加剂,并与传统材料导电碳黑在形貌、循环性能以及电极内阻方面进行了比较。研究结果表明,使用CNT作为导电添加剂,能够在电极颗粒表面形成网状包覆结构,由于这种结构能够提高电极的稳定性,以及CNT材料本身的高电导率,使得LiCoO2/CNT电极表现出较好的电化学性能。     

锂镍钴锰氧正极材料的热聚合法制备及性能表征研究

经过几十年的发展,锂离子电池由于其在能量密度、循环寿命等方面的优势,在小心电子产品上获得了广泛的应用。在目前的商业化锂离子电池产业中,应用最广泛的正极材料是由Good enough等开发的LiCoO2材料,但是其有毒、热稳定性差等特点,导致其难以得到进一步的应用。因此,通过开发他们的复合材料成为了锂离子电池正极材料开发的主要研究方向之一。论文主要对LiNi1/3Co1/3Mn1/3O2材料的热聚合法制备及性能表征进行了一定的研究。     

Enhanced electrochemical performance and thermal stability of La2O3-coated LiCoO2

An enhanced electrochemical performance LiCoO₂ cathode was synthesized by coating with various wt.% of La₂O₃ to the LiCoO₂ particle surfaces by a polymeric method, followed by calcination at 923 K for 4 h in air. The surface-coated materials were characterized by XRD, TGA, SEM, TEM, BET and XPS/ESCA techniques. XRD patterns of La₂O₃-coated LiCoO₂ revealed that the coating did not affect the crystal structure, α-NaFeO₂, of the cathode material compared to pristine LiCoO₂. TEM images showed a compact coating layer on the surface of the core material that had an average thickness of about ∼15 nm. XPS data illustrated that the presence of two different environmental O 1s ions corresponds to the surface-coated La₂O₃ and core material. The electrochemical performance of the coated materials by galvanostatic cycling studies suggest that 2.0 wt.% coated La₂O₃ on LiCoO₂ improved cycle stability (284 cycles) by a factor of ∼7 times over the pristine LiCoO₂ cathode material and also demonstrated excellent cell cycle stability when charged at high voltages (4.4, 4.5 and 4.6 V). Impedance spectroscopy demonstrated that the enhanced performance of the coated materials is attributed to slower impedance growth during the charge-discharge processes. The DSC curve revealed that the exothermic peak corresponding to the release of oxygen at ∼464 K was significantly smaller for the La₂O₃-coated cathode material and recognized its high thermal stability.     

锂离子负极材料NiFe_2O_4/Graphene复合材料的制备和电化学性能

通过水热法合成了NiFe2O4/Graphene纳米复合材料,采用XRD和SEM对其晶相结构和形貌进行了表征,并将其作为锂离子电池活性材料组装成模拟电池,考查电化学性能。结果表明NiFe2O4/Graphene复合材料在100mA/g的电流密度下首次放电容量达970mAh/g,循环20次后,容量保持在668mAh/g,相比纯的NiFe2O4,具有较好的循环稳定性,这种优异的电化学性能归因于复合材料的纳米结构和NiFe2O4与Graphene的协同作用。     

MoO3/石墨烯/碳纳米管复合阴极在MFCs中的应用

采用简单的水热合成法制备了氧化钼（MoO₃）/石墨烯（GNS）/碳纳米管（CNT）复合材料。用扫描电子显微镜（SEM）和X射线衍射仪（XRD）表征了材料的形貌和结构。用循环伏安（CV）和线性扫描（LSV）测试了材料的氧还原催化性能,结果发现,复合材料的氧还原电流和起始电位均大大优于单一的MoO₃,表现出较好的催化性能。含有3 mg·cm^-2 MoO₃/GNS/CNT复合材料作为阴极催化剂的MFC最大功率密度为510 mW·m^-2,达到商业铂碳的83%。因此,廉价的MoO₃/GNS/CNT复合材料作为MFC阴极氧还原催化剂具有巨大的应用潜力。     

Effects of Al2O3 and LiAlO2 Co-coating on electrochemical properties of LiNi0.8Co0.1Mn0.1O2 cathode materials

Lithium-ion batteries are widely used in aerospace, power vehicles, portable electronic devices and other fields because of their environmental friendliness, rechargeable cycle and high energy density. The nickel-cobalt-manganese ternary materials with high nickel has high specific discharge capacity and is regarded as one of the most promising cathode materials. However, with the increase of the number of cycles, the cycle performance becomes worse and the specific capacity decays sharply. In this work, Al₂O₃ and LiAlO₂ were coated on the surface of NCM811 by combining ball milling mixing and solid-phase synthesis to prepare the AL-NCM811 cathode material. The coating thickness formed by Al₂O₃ and LiAlO₂ was 10–70 nm, which effectively improves the cycle stability and rate performance of NCM811 material. When charged and discharged at 0.1C, the first discharge specific capacity and capacity retention rate after 100 cycles of 0.5AL-NCM811 were 196.26 mAh/g and 96.47%, respectively, while those of NCM811 were only 193.78 mAh/g and 72.18%, respectively. When the current density was 5.0C, the discharge specific capacity of 0.5AL-NCM811(139.16 mAh/g) was 55.368 mAh/g higher than that of NCM811(83.80 mAh/g).     

纳米银颗粒包覆氧化铝的制备及其硅胶复合材料热导率

用化学方法在微米级球形氧化铝上包覆纳米银颗粒,包覆层可在空气中稳定存在。银包覆层明显提高了氧化铝/硅胶复合材料的热导率。复合材料断面形貌图显示纳米银包覆层改善了氧化铝与硅胶之间的界面结合,并且银颗粒起到桥梁作用连接起相邻的氧化铝。     

Preparation and optimization of ZrO2 modified P2-type Na2/3Ni1/6Co1/6Mn2/3O2 with enhanced electrochemical performance as cathode for sodium ion batteries

Surface stabilization is necessary for cathode materials to gain a long-term cycling stability because of unfavorable side reactions and exfoliation caused by corrosive environment. To improve the cyclic stability of P2-type ternary cathode Na_2/3Ni_1/6Co_1/6Mn_2/3O₂ for sodium ion batteries, we prepare a ZrO₂-coated Na_2/3Ni_1/6Co_1/6Mn_2/3O₂ through a simple wet chemical method. The coating layer is distributed homogeneously on the surface, and the fraction of ZrO₂ (1 wt-%, 2 wt-%, 3 wt-%, 4 wt-%, 5 wt-%) helps control the thickness of the coating layer. It turns out that all the materials exhibit pure P2 structure without any impurities. The material with a 2 wt-% ZrO₂ coating exhibits the best electrochemical performance in rate capability and long-term cyclic stability. It delivers a superior initial discharge capacity of 140 mA h·g⁻¹ between 2 and 4.5 V at 20 mA g⁻¹. Even cycles at high current density (100 mA g⁻¹), it shows 106 mA h·g⁻¹ reversible discharge capacity with 88% capacity retention after 300 cycles. The improvement in electrochemical performance is attributed to the segregation of cathode materials from the corrosive electrolyte by the nano-sized ZrO₂ layer. The EIS results confirm that a thin ZrO₂ coating layer can effectively protect the electrode from dissolution and stabilize the SEI film. This study can be used to develop the electrochemical performance of cathode materials for sodium ion batteries by surface modification via ZrO₂.     

Al_2O_3包覆锂电池正极材料LiMn_2O_4的合成及电化学性能研究

研究了在锂离子电池尖晶石Li Mn2O4正极材料上包覆Al2O3来改善材料在循环过程中的容量衰减问题。通过SEM和X射线衍射研究材料的表观形貌和晶体结构。在电化学性能测试中,发现包覆Al2O3可以减少材料与电解液的直接接触,阻止了电解液对尖晶石的侵蚀,最终有效地改进锂电池正极材料Li Mn2O4的电化学性能。