锂离子电池正极材料LiMn2O4的合成与晶体结构（英）

Spinel LiMn₂O₄ powders were prepared using two-step synthesis method consisting of solid-state reaction method and citrate modified sol-gel method. The effects of the calcination temperature and the Li/Mn ratio of raw materials were studied on the physicochemical and electrochemical properties of the spinel LiMn₂O₄ powders, such as crystallinity, lattice constant and density. The title compound was characterized by powder X-ray diffraction (XRD), scanning electron microscopy (SEM) and transmission electron microscopy (TEM). Polycrystalline LiMn₂O₄ powers calcined at 750 ℃ were found to be composed of very uniformly-sized microcrystal with an average particle size of 300 nm. The improvement in electrochemical properties was mainly attributed to the process of re-grinding by absolute alcohol.     

Synthesis and characterization of phosphate-modified LiMn2O4 cathode materials for Li-ion battery

<正>LiMn_2O_4 spinel cathode materials were modified with 2 wt.%Li-M-PO_4(M=Co,Ni,Mn) by polyol synthesis method.The phosphate surface-modified LiMn_2O_4 cathode materials were physically characterized by X-ray diffraction(XRD),scanning electron microscopy(SEM) and energy dispersive X-ray spectroscopy(EDS).The charge-discharge test showed that the cycling and rate capacities of LiMn_2O_4 cathode materials were significantly enhanced by stabilizing the electrode surface with phosphate.     

Electrochemical properties and synthesis of LiAl0.05Mn1.95O3.95F0.05 by a solution-based gel method for lithium secondary battery

The cathode materials, LiMn₂O₄, LiAl_0.05Mn_1.95O₄ and LiAl_0.05Mn_1.95O_3.95F_0.05 were firstly prepared by a simple solution-based gel method using the mixture of acetate and ethanol as the chelating agent. The synthesized samples were investigated by X-ray diffraction, scanning electronic microscope and differential and thermal analysis. The as-prepared powders were used as positive materials for lithium-ion battery, whose discharge capacity and cycle voltammogram properties were examined. The results revealed that LiAl_0.05Mn_1.95O_3.95F_0.05 synthesized by the solution-based gel method had higher initial capacity than LiAl_0.05Mn_1.95O₄ and better capacity retention rate (92%) than that of LiAl_0.05Mn_1.95O₄ and LiMn₂O₄, which revealed that Al and F dual-doped LiMn₂O₄ could gain better electrochemical properties of LiMn₂O₄ than only the Al-doped LiMn₂O₄.     

Cu-Sn-P-LiMn2O4纳米复合材料镀层的XPS和AES研究

采用化学复合镀技术，在Q₂₃₅碳钢片表面制备了Cu-Sn-P-LiMn₂O₄纳米复合材料镀层。用扫描电子显微镜(SEM)观察外貌；称重法测定厚度；通过5% NaCl溶液、1% H₂S气体加速腐蚀试验、抗粘性试验及室温氧化试验等多种手段测定其性能。用X-射线光电子能谱(XPS)及俄歇电子能谱(AES)测定其价态及组成。结果表明:Cu-Sn-P-LiMn₂O₄纳米复合材料镀层的性     

电解Co-Ni-Mn合金制备LiCo1/3Ni1/3Mn1/3正极材料

由Co-Ni-Mn合金出发，采用电解方法合成了含3种过渡金属元素的前驱物，再利用该前驱物制备了锂离子二次电池正极材料LiCo_1/3Ni_1/3Mn_1/3。XRD测试结果表明通过该方法制备的正极材料具有较好的层状结构，SEM测试则显示材料由规则形状的1 μm左右颗粒组成。通过XPS实验证明Co、Ni、Mn 3种过渡金属元素在该材料中的价态分别为+3，+2，+4。采用循环伏安法对材料的电化学行为进行了研究，表明该材料具有较好的充放电可逆性。该材料在150 mA·g^-1电流下经过50周的恒电流充放循环后容量仍能保持在160 mAh·g^-1。     

Mn2O3纳米结构的简易合成与电化学性质

用简易的室温或水热方法制备出不同形貌的MnCO₃微结构。经600 ℃热处理后,室温制备MnCO₃转变成Mn₂O₃胶体片,而水热制备MnCO₃样品则形成多孔Mn₂O₃纳米结构。然而,室温制备MnCO₃经120 ℃热处理后形成Mn₂O₃晶相。制备样品经过XRD和SEM表征表明,热处理MnCO₃前驱物形成Mn₂O₃过程导致产物形貌与结构变化。其形成机理又通过TEM和FTIR进一步研究。Mn₂O₃纳米结构的电容性质通过循环伏安法表征,结果表明Mn₂O₃形貌与结构对其电容有重要影响。     

高容量锂离子电池正极材料LiNi0.9Co0.05Mn0.025Mg0.025O2的合成及电化学性能

以β-Ni0.9Co0.05Mn0.025Mg0.025(OH)2和LiOH.H2O为原料通过高温固相法合成了球形LiNi0.9Co0.05Mn0.025Mg0.025O2。采用热重-差热分析了反应过程,采用X射线衍射和扫描电镜对粉末的结构和形貌进行了表征。采用充放电测试和循环伏安测试对材料电化学性能进行了研究。结果表明:750℃煅烧12 h合成的LiNi0.9Co0.05Mn0.025Mg0.025O2为Li原子混排较少的良好层状结构,二次颗粒尺寸在15μm左右,且具有最高的放电比容量和良好的循环性能,在0.2C,2.8~4.3 V的条件下,首次放电比容量达207 mAh.g-1,40次循环后容量保持率为92.5%。     

工艺参数对o-LiMnO2相纯度及Li1.6Mn1.6O4合成的影响及作用（英文）

以MnSO4,KMnO4及LiOH为原料,经水热处理后得到LiMnO2,再由固相焙烧得到尖晶石相Li1.6Mn1.6O4,酸洗处理后得到锂离子筛。研究了水热温度,氧气和MnO4-/Mn2+的物质的量之比(nMnO4∶nMn^2+)对所得LiMnO2的组成及相应前驱体Li1.6Mn1.6O4酸处理中Mn溶损率的影响。开路电势测量及化学分析表明,氧气会参与反应。若按照理论氧化剂用量nMonO4∶nMn^2+=1∶4进行水热反应会导致杂质Li2MnO3和LiMn2O4的生成。若控制水热温度为160℃,nMnO4∶nMn^2+=1∶6时可得到纯相正交LiMnO2(o-LiMnO2)。所得离子筛在高镁锂比盐湖卤水中Li+吸附容量可达42.87 mg·g^-1,且对Li+具有优异的选择吸附性并遵循化学吸附过程。经过5个循环后吸附容量保持在37.21 mg·g^-1,锰溶损率降至0.34%。     

LiAl0.03Mn1.97O4的流变相辅助微波合成以及电化学性能

采用一种特殊微波合成法，流变相辅助微波合成法，制备了结晶度好、纯度高的尖晶石相的锂离子电池正极材料LiAl0.03Mn1.97O4。对其进行了XRD分析和SEM研究，并就结构、形貌与传统固相法制备的LiMn2O4、LiAl0.03Mn1.97O4进行了比较。采用这种流变相辅助微波合成法制备的LiAl0.03Mn1.97O4具有优良的电化学性能，电化学性能测试表明，这种材料具有比较高的首次放电容量（115mAh／g）以及良好的可逆性、优异的循环性能，25次循环结束比容量几乎不变，保持在115mAh／g左右，衰减性得到很好的改善。     

Li2CO3、NiO和电解MnO2合成高容量LiNi0.5Mn1.5O4及其表征

Well-developed crystalline LiNi_0.5Mn_1.5O₄ was prepared by solid-state reaction using Li₂CO₃, NiO and electrolytic MnO₂ at high heating and cooling rate. X-ray diffraction (XRD) patterns and scanning electron microscopic (SEM) images showed that LiNi_0.5Mn_1.5O₄ synthesized at 900 ℃ and 950 ℃ had cubic spinel structure with clearly defined shape. LiNi_0.5Mn_1.5O₄ spinel phase decomposed at 1 000 ℃ accompanying with structural and morphological degradation. TG measurement revealed that the weight loss during heating process could be mostly gained in cooling process, and the upward tendency of weight loss during heating process decreased, while that of irreversible weight loss rapidly increased with the increase of temperature. LiNi_0.5Mn_1.5O₄ powders prepared at 900 ℃ for 12 h delivered the maximum discharge capacity of 134 mAh·g^-1 with good cyclic performance at 2/7 C. In addition, by adjusting the calcination time at 900 ℃, the capacity and cycling performance of LiNi_0.5Mn_1.5O₄ were further enhanced.     

锂离子电池正极材料LiMn_(2-2x)Sm_xSr_xO_4的合成及电化学性能

采用高温固相反应合成了一系列的LiMn2-2xSmxSrxO4正极材料(0≤x≤0.1);采用X射线衍射仪分析了合成产物的晶体结构;利用充放电试验测定了产物的电化学性能,利用电化学阻抗谱分析了产物的电化学循环机理.结果表明,所合成的LiMn2-2xSmxSrxO4(x=0,0.01,0.02,0.03,0.04,0.05)样品均保持尖晶石相,属于Fd3m空间群.LiMn1.9Sm0.05Sr0.05O4的电化学性能最佳,首次放电容量为96.8 mAh/g,在3.0~4.4 V区间内50次循环后容量保持率超过96%.与此同时,LiMn2O4和LiMn1.90Sm0.05Sr0.05O4的电极阻抗变化不同,进而影响其电化学性能.     

锰离子掺杂对LiCoPO4性能的影响

应用溶胶-凝胶法合成了锰掺杂的LiCoPO4正极材料.X射线衍射、扫描电镜和循环伏安等电化学测试表明,少量锰离子掺杂不影响LiCoPO4的晶格结构,且明显改善了LiCoPO4正极材料电化学性能.锰掺杂量为1%时得到的LiMn0.01Co0.99PO4正极材料具有最好的电化学性能,以0.1C倍率放电时,首次放电比容量可达130.6 mAh/g.     

锂离子电池负极材料ZnMn2O4微米空心球的制备和电化学性能

通过溶剂热方法合成了ZnMn2O4微米空心球,并探讨了其形成机理。采用XRD,SEM,TEM等测试手段对产物的结构、形貌和组成进行了表征。实验结果表明,溶剂热反应条件如反应温度、反应介质对于产物的结构和形貌起着关键作用。在140℃,采用乙醇和水作为反应介质,反应6 h可以制备出直径约3μm的ZnMn2O4微米空心球;当以乙醇为溶剂,反应6 h可以得到团聚的尺寸约250 nm的ZnMn2O4纳米颗粒。将所制备的ZnMn2O4微米空心球/纳米颗粒组装成锂扣式模拟电池,考察其电化学脱嵌锂性能。电化学测试结果显示,与ZnMn2O4纳米颗粒相比,空心结构的ZnMn2O4微米球具有较高的初始放电容量(1335 mAh·g-1)和较好的倍率性能,有望作为锂离子电池的新型负极材料。     

LiNiyCo0.1－yMn1.9O4正极材料的沉淀法制备及其结构与电化学性能

采用沉淀法制备了尖晶石型LiMn₂O₄和LiNi_yCo_0.1－yMn_1.9O₄ (y=0, 0.05, 0.1)正极材料. 应用FT-IR、XRD和SEM技术对不同掺杂样品的相结构与形貌进行了表征, 并用恒电流充放电测试和电化学阻抗技术研究了样品的电化学行为. FT-IR、XRD和SEM结果显示: 随着掺杂型LiNi_yCo_0.1－yMn_1.9O₄ 样品中Ni含量的减少, 位于519 cm^-1处的红外峰向高频方向移动; Ni、Co 或Ni/Co的掺杂降低了LiMn₂O₄的晶格参数; 掺杂型 LiNi_yCo_0.1－yMn_1.9O₄ 样品具有更好的分散度和小的粒径. 电化学实验结果表明, 不同成分的掺杂导致电化学性能改善的原因不尽相同. 其中LiNi_0.05Co_0.05Mn_1.9O₄样品因其较低的电化学极化和较大的Li⁺扩散系数而具有较好的电化学性能.     

LiMn_2O_4的高温比容量衰减研究

采用高温固相法合成了LiMn2 O4电极材料 ,运用电化学和阴极膜X射线衍射等方法研究了LiMn2 O4在高温 (≥ 50℃ )下 ,循环时比容量衰减的现象及其衰减机理。结果表明 ,温度越高 ,LiMn2 O4的自放电越严重 ;贮存时间越长 ,LiMn2 O4的可逆容量损失越大 ,平均放电电压越低 ;高温下LiMn2 O4中Mn的溶解是造成比容量衰减的重要原因。通过掺杂微量元素的方法能有效地改善尖晶石LiMn2 O4的高温循环性能     

碳包覆Li3V2(PO4)3:溶胶-凝胶法合成及性能

利用V₂O₅、LiOH·H₂O、H₂O₂、NH₄H₂PO₄与柠檬酸为原料,通过溶胶-凝胶法合成了碳包覆的Li₃V₂(PO₄)₃复合正极材料。采用XPS、XRD、SEM、TEM、拉曼光谱和电化学方法对材料的性能进行了研究。还研究了其结构与焙烧温度、样品电导率和电化学性能的关系。研究表明复合材料具有空间群为P2₁/n的单斜结构,表面包覆粗糙多孔的碳层。在800 ℃下制备的碳包覆样品的电子导电率高达9.81×10^-5 S·cm^-1,约为高温固相氢气还原法制备的未包覆碳Li₃V₂(PO₄)₃的10000倍。测试结果表明碳包覆Li₃V₂(PO₄)₃的电化学性能远优于未包覆碳的样品。在3.0～4.3 V电压范围内,以0.1C和2C倍率充放电时,碳包覆的Li₃V₂(PO₄)₃具有高比容量(分别为128和109 mAh·g^-1)和优异的循环性能。     

溶剂热法制备Mn掺杂LiFePO4正极材料及其电化学性能

以水和乙二醇作溶剂,采用溶剂热法合成不同Mn掺杂量的LiFePO_4正极材料,并对其物相、形貌和电化学性能进行研究。结果表明,Mn在LiFePO_4正极材料中存在积极作用,Mn的掺杂可以提高LiFePO_4的电化学性能。一方面,少量Mn的掺杂可以拓宽锂离子扩散通道,减小电荷转移阻抗。但另一方面,当Mn的掺杂量过多时,其自身较差的动力学性质会导致电荷转移受阻,造成电池极化和严重的容量衰减。     

锂离子电池正极材料LiMn2-xCrxO4电化学性能的研究

针对尖晶石型LiMn2O4锂离子电池正极材料的容量衰减,提出了相应的抑制方法,所合成的LiMn2-xCrxO4(0相似文献   

溶胶-凝胶法制备Li3V2(PO4)3及其性能研究

0引言具有类NASICON结构的Li3V2(PO4)3是继过渡金属氧化物LMO后的一种新型的锂离子二次电池正极材料。与目前市场上应用最为广泛的正极材料LiCoO2相比,Li3V2(PO4)3具有超常的稳定性,即使在脱出的Li 与过渡金属原子的物质的量之比大于1的时候仍然具有超乎寻常的稳定性,而通常情况下1mol LiCoO2在脱出0.5mol Li 就会变得不稳定。并且Co是一种战略物资,全球储量十分有限;Co也是一种有毒金属,对于环境污染较为严重。LiNiO2因其合成较为困难而使应用受限,尖晶石LiMn2O4虽然属于环境友好型化合物,但其理论比容量仅为148mAh·g-1,且…     

Enhancement of the electrochemical properties of LiMn2O4 through Al3+ and F- co-substitution

The cathode-active materials LiMn2O4, LiAl0.1Mn1.9O4, and LiAl0.1Mn1.9O3.9F0.1 were synthesized by a microwave-assisted sol-gel method. The influence of different doping elements on the structural and electrochemical properties of the as-prepared samples was investigated by thermogravimetric analysis (TGA), X-ray diffraction (XRD), transmission electron microscopy (TEM), and electrochemical experiments. The results indicated that fluorine plays an important role in controlling the morphology, and the doped aluminum could enhance significantly the stability of spinel-type LiMn2O4. The initial discharge capacity of the Al3+ and F- co-substituted specimen reached 129.8 mA h/g and has a high capacity retention after 40 cycles. The outstanding electrochemical properties of LiAl0.1Mn1.9O3.9F0.1 make it a possible promising cathode material for lithium-ion batteries.