改性LiMn_2O_4的高温电化学性能

采用高温固相反应法制备改性的LiMn2O4锂离子电池正极材料.利用SEM、XRD等方法表征产物的结构特性.结果表明:所得产物均具尖晶石型LiMn2O4结构,该样品经Li2CO3改性后用作锂离子电池正极,于常温和高温下的循环性能均得到明显改善.     

LiCoO2对LiMn2-xMxO4正极材料的混合改性研究

采用机械混合层状LiCoO2和经过多元掺杂改性后尖晶石型LiMn2-xMxO4(M=Co Cr La,x=nCo nCr nLa,且0相似文献   

尖晶石LiMn_2O_4的表面改性研究

采用溶胶_凝胶法合成尖晶石LiMn2 O4 ,并以LiCoO2 对其进行包覆 ,用XRD、SEM、EPMA等方法对修饰的尖晶石结构和性能进行研究 .结果表明 ,经包覆的LiMn2 O4 在 70 0℃焙烧 10h所得的晶粒是表层富含Co的立方尖晶石 ,而且晶粒中Co3+的含量呈现出从表到里递减的梯度分布 .以该材料作锂离子电池正极 ,虽初始容量稍有降低 ,但能有效地降低Mn2 +在电解质中的溶解 ,而且对Jahn_Teller效应有一定的抑制作用 ,包覆的LiMn2 O4 尖晶石正极材料比未包覆的有更好的循环性能     

LiCoO_2和LiMn_2O_4在水系电解液中的赝电容研究

用溶胶-凝胶法合成了LiCoO2和LiMn2O4样品粉末。以LiCoO2和LiMn2O4电极为正极,活性炭(AC)电极为负极,分别组装成模拟非对称超级电容器AC/LiCoO2和AC/LiMn2O4,通过循环伏安、恒流充放电和电化学阻抗研究其电容性能。测试结果表明,这类非对称电容器在Li2SO4溶液中展示了较好的电容性能。在电压范围(0～1.4)V、电流密度为100mA·g-1时,AC/LiCoO2和AC/LiMn2O4电容器的初始比电容分别为45.9和44.6F·g-1。但在大电流密度下,AC/LiMn2O4具有更大的比电容和更好的循环性能。实验结果还表明,在水系电解液中,LiCoO2和LiMn2O4均是通过Li+脱嵌导致过渡元素(Co,Mn)价态变化所产生的赝电容来实现储能。     

LiCoO2对LiMn2O4改性过程的研究

在LiCoO2、LiMn2O4、LiNiO2这三种锂离子电池正极材料中,尖晶石LiMn2O4由于具有价廉、对环境友好、使用安全的显著优点,被普遍认为是最有希望的新型正极材料。但该材料在高温下较快的容量衰减制约了其规模应用[1~3]。为改善LiMn2O4的高温性能,各国学者普遍采用掺杂法,即在制备L     

尖晶石型LiMn2O4电池材料的元素掺杂

尖晶石型LiMn2O4正极材料因资源丰富、无毒、安全及制备简单、技术较成熟等优点而成为最具竞争力的新一代商用锂离子二次电池的正极材料之一.由于LiMn2O4的循环稳定性、高温(＞55℃)稳定性和大电流放电等因素限制了推广应用.本文从材料的结构组成对锂离子嵌脱过程的作用机理,论述了元素掺杂对尖晶石型LiMn2O4正极材料电化学特性的影响,指出了元素掺杂本体改性锰酸锂正极材料的方法和特点.     

锂离子电池LiMn2O4正极材料的高温改性

锂离子电池LiMn2O4正极材料的高温改性;锂离子电池;正极材料;尖晶石;LiMn2O4;包覆     

喷墨打印制备LiMn2O4薄膜电极及其电化学性能

通过溶胶-凝胶法制备了尖晶石LiMn2O4.用分散剂Lormar D,经超声分散制得了含LiMn2O4粒子的打印"墨水",并使用计算机喷墨打印的方法制得LiMn2O4薄膜电极.薄膜电极的厚度约为1.8 μm.用XRD、TG-DTA、SEM、循环伏安、电化学阻抗谱和充放电等方法对材料和电极的性能进行了表征.结果表明,在较大电流100 μA·cm-2(2C)的充放电情况下,电极能保持好的稳定性,其首次放电容量为109 mAh·g-1,充放电54次后,其容量仍可保持97.4%,为105 mAh·g-1,这可归因于薄膜电极中尖晶石LiMn2O4的晶型完整,LiMn2O4粒子小以及稳定的超薄电极结构.     

喷墨打印制备LiMn2O4薄膜电极及其电化学性能

通过溶胶-凝胶法制备了尖晶石LiMn2O4. 用分散剂Lormar D, 经超声分散制得了含LiMn2O4粒子的打印“墨水”, 并使用计算机喷墨打印的方法制得LiMn2O4薄膜电极. 薄膜电极的厚度约为1.8 μm. 用XRD、TG-DTA、SEM、循环伏安、电化学阻抗谱和充放电等方法对材料和电极的性能进行了表征. 结果表明, 在较大电流100 μA·cm-2 (2C)的充放电情况下, 电极能保持好的稳定性,其首次放电容量为109 mAh·g-1, 充放电54次后, 其容量仍可保持97.4%, 为105 mAh·g-1, 这可归因于薄膜电极中尖晶石LiMn2O4的晶型完整, LiMn2O4粒子小以及稳定的超薄电极结构.     

导电氧化物AZO对尖晶石型LiMn_2O_4高温性能的改善及研究

采用溶胶凝胶法对尖晶石型LiMn2O4正极材料进行铝掺杂氧化锌(AZO)包覆改性,并通过XRD、SEM、EDS、TEM、EIS、ICP-AES和充放电测试等手段对其结构,形貌及电化学性能进行表征。研究结果表明,AZO包覆层有效的阻止了LiMn2O4颗粒和电解液的直接接触,抑制了高温下锰溶解,明显改善了LiMn2O4的高温循环性能。1.5wt%AZO包覆的LiMn2O4正极材料在高温(55℃)1C时,首次放电比容量为114 mAh·g-1,经过100次循环后,容量保持率仍高达95.4%,远高于未包覆LiMn2O4的70.6%。此外,1.5wt%AZO包覆的LiMn2O4表现出了优越的大倍率放电性能,在10C下放电比容量能达到99 mAh·g-1。     

基片温度对LiCoO2薄膜结构与电化学性能的影响

采用射频(RF)磁控溅射技术制备了用于全固态薄膜锂电池的非晶态和多晶LiCoO2阴极薄膜,利用XRD和SEM研究了沉积温度对LiCoO2薄膜结构和形貌的影响,并研究了高温退火后薄膜的电化学性能.研究结果表明,随著基片温度的不同,薄膜成分、表面形貌以及电化学行为有明显差异.室温沉积的薄膜很难消除薄膜中Li2CO3的影响,经过高温退火处理后也无法形成有效的多晶LiCoO2薄膜,而150℃沉积的薄膜经过高温退火后形成了有利于锂离子嵌入的多晶LiCoO2结构,薄膜显示出了较好的电化学性能.     

Influences of different cobalt sources on the properties of synthesized LiCoO2

Since 1991, LiCoO2 used as cathode material of lithium-ion rechargeable batteries has attracted much attention in the industry of portable power apparatus such as mobiles, laptops and camcorders, etc. However, the production technologies of LiCoO2 have always been possessed by the foreign corporations. Although a plenty of research work has been performed in domestics, it is almost impossible to surpass the technological rampart, which renders our state to subject to much foreign exchange consumption.Many preparation methods such as solid state reaction, sol-gel process and hydrothermal synthesis et al have been reported in the literature. Via our studies, it is found that in the process of LiCoO2 synthesis not only lithium sources but also cobalt sources can play an important part in the physical and electrochemical properties, and also have a remarkable influence on the properties of LiCoO2.But as for the different synthesis methods, the necessary cobalt source is different, and as for the same synthesis method, the LiCoO2 prepared with different cobalt sources has different electrochemical performance.So far, the detailed findings on the LiCoO2 cathode material synthesized with various cobalt sources have not been reported yet in the literature. In this paper, the following work has been carried out.The LiCoO2 cathode material was synthesized by liquid-phase soft-chemistry process and solid state reaction at higher temperature with different cobalt sources respectively, and characterized by XRD, BET, SEM, TEM, laser particle size distribution and electrochemical testing. Its properties were compared. The effects of different cobalt sources, aqueous ammonia and ethanol additives on the physical and electrochemical properties of LiCoO2 cathode materials were investigated. The results have demonstrated that the different cobalt sources, aqueous ammonia and ethanol additives have remarkable influences on the physical and electrochemical properties of LiCoO2 cathode material. When liquid-phase soft-chemistry process is used to synthesize LiCoO2 cathode material,most excellent cobalt source when high-temperature solid state reaction method is used to prepare LiCoO2 cathode materials. The optimal sintering temperature range is 800℃～820 ℃ when liquid-phase soft-chemistry process is used to synthesize LiCoO2 cathode materials. Liquid-phase soft-chemistry process is superior to high-temperature solid state reaction method when LiCoO2 cathode materials is prepared.     

以LiCoO2为阴极的全固态薄膜锂电池的研究

Amorphous and oriented polycrystalline LiCoO2 thin films, used as cathode material for an all-solid-state thin film battery, were fabricated by using RF magnetron sputtering and annealed at different temperatures. The morphology and structure of LiCoO2 thin films were characterized by scanning electron microscopy and X-ray diffraction. All-solid-state thin film batteries, comprised of LiCoO2 cathode films with different structures, lithium phosphorous oxynitride electrolyte film and metallic lithium anode film, was successfully prepared and their properties were examined by chronopotentiometry. Results showed that the structure and crystallinity of the LiCoO2 films strongly influenced the electrochemical performance of all-solid-state thin film lithium batteries. Worth nothing was the battery with an oriented polycrystalline LiCoO2 film it exhibited the best electrochemical performance, and delivered a discharge capacity of ～55.4 μAh/cm2μm. Furthermore, when subjected to over 450 charge/discharge cycles, that battery suffered no obvious fode in capacity.     

Synthesis and electrochemical properties of nanostructured LiCoO2 fibers as cathode materials for lithium-ion batteries

Nanostructured LiCoO2 fibers were prepared by the sol-gel related electrospinning technique using metal acetate and citric acid as starting materials. The transformation from the xerogel fibers to the LiCoO2 fibers and the nanostructure of LiCoO2 fibers have been investigated in detail. The LiCoO2 fibers with 500 nm to 2 mum in diameter were composed of polycrystalline nanoparticles in sizes of 20-35 nm. Cyclic voltammetry and charge-discharge experiments were applied to characterize the electrochemical properties of the fibers as cathode materials for lithium-ion batteries. The cyclic voltammogram curves indicated faster diffusion and migration of Li+ cations in the nanostructured LiCoO2 fiber electrode. In the first charge-discharge process, the LiCoO2 fibers showed the initial charge and discharge capacities of 216 and 182 (mA.h)/g, respectively. After the 20th cycle, the discharge capacity decreased to 123 (mA.h)/g. The X-ray diffraction and high-resolution transmission electron microscopy analyses indicated that the large loss of capacity of fiber electrode during the charge-discharge process might mainly result from the dissolution of cobalt and lithium cations escaping from LiCoO2 to form the crystalline Li2CO3 and CoF2 impurities.     

锂空气电池空气电极LiCoO2电催化性能研究

自设计建立锂空气电池实验装置,研究以掺入LiCoO2作为电催化剂的空气正极的电化学性能及其放电前后催化剂结构的变化.循环伏安、XRD及充放电测试等表明,LiCoO2能够很大程度地改善空气电极的放电性能.尤其是在放电前,将掺有LiCoO2的空气正极充电至4.1 V,此时LiCoO2的Co元素呈现较高的价态（Co3＋/Co...     

Recovered LiCoO2 as anode materials for Ni/Co power batteries

LiCoO(2) material is recovered from spent lithium-ion batteries and investigated as anode materials for Ni/Co power batteries for the first time. LiCoO(2) electrodes with a small amount of S-doping display excellent electrochemical properties. The electrochemical reactions occurring on M0 electrodes during the first several cycles and after being activated are proposed, respectively. A function mechanism of S powder on M10 electrode is also proposed.     

晶体的择优取向与LiCoO2正极材料X射线衍射峰的强度比

采用高温固相反应法合成了锂离子电池正极材料LiCoO2, 用粉末X射线衍射(XRD)和扫描电子显微镜(SEM)等技术对材料的形貌与结构进行分析. 平面反射和透射X射线粉末衍射数据表明, 目前商品LiCoO2样品XRD图谱的(104)和(003)衍射峰强度比(I(104)/I(003))主要反映了LiCoO2晶体c轴方向的择优取向, 而不是Li、Co原子的占位有序程度. I(104)/I(003)比值越小, 晶体择优取向度越高. 晶体无择优取向LiCoO2粉末材料的衍射峰强度比I(104)/I(003) 应为95%左右. 因此, 不能用I(104)/I(003) 的比值大小作为实际LiCoO2材料晶体内Li、Co 原子排列是否有序的主要证据. 澄清了长期有争议的关于锂离子二次电池正极材料LiCoO2的X射线衍射峰强度比问题.     

Novel application of LiCoO_2 as a high-performance candidate material for supercapacitor

Electrochemical performances of LiCoO2 as a candidate material for supercapacitor are systematically investigated. LiCoO2 nanomaterials are synthesized via hydrothermal reaction with consequent calcination process. And the particle size increases as the calcination temperature rises.LCO-650 sample with the largest particle size displays the maximum capacitances of 817.5 Fg-1with the most outstanding capacity retention rate of 96.8% after 2000 cycles. It is shown that large particle size is beneficial to the electrochemical and structural stability of Li CoO2 materials. We speculate that the micron-sized waste LiCoO2 materials have great potential for supercapacitor application. It may provide a novel recovered approach for spent LIBs and effectively relieve the burdens on the resource waste and environment pollution.     

采用新颖喷墨打印技术制备的薄膜LiCoO2电极及其电化学性能

采用喷墨打印技术制备了LiCoO2薄膜电极. 用X射线衍射、扫描电镜(SEM)、循环伏安和恒电流充放电试验对薄膜电极进行结构表征和电化学性能测试. SEM结果表明, 所制备的薄膜电极表面粒子分布均匀, 厚度约为1.27 μm. 经过轻微热处理(450 ℃, 30 min)的薄膜LiCoO2电极呈现出稳定的充放电循环性能. 当以20 μA/cm2进行充放电时, 第50次循环容量保持率约为首次放电容量(81 mA·h/g)的87%, 10次循环后的充放电过程的充放电效率均接近100％.     

钛掺杂对不同形貌LiCoO2电化学性能的影响

采用SEM、XRD、恒电流充放电、电化学交流阻抗谱等方法研究了钛掺杂对不同形貌LiCoO2电化学性能的影响. 结果表明, 钛掺杂在不改变材料晶体结构的情况下, 能显著地改善LiCoO2的电化学性能, 且在较高倍率放电制度下(1 C), 掺杂对不同形貌LiCoO2的放电电压平台的影响效果不同. 掺杂后的二次粒子团聚体以1 C放电, 20次循环后3.8 V平台(电压大于3.8 V时的放电容量占总放电容量的百分比) 的保持率为60％, 优于掺杂后的大粒径一次粒子分散体的平台保持率(40％). 电化学交流阻抗谱研究表明, 钛掺杂对于抑制LiCoO2二次粒子在高倍率放电制度下循环过程中电化学阻抗的增加更为有效.