锂离子电池正极材料LiMnPO4研究进展

综述了新型锂离子电池正极材料LiMnPO4的研究进展,重点对该材料的结构、结构与电化学性能的关系、阳离子掺杂对材料性能的影响、多种合成方法和材料改性措施进行了较详细的评述,并对该材料的应用前景进行了展望.     

锂离子电池掺钴正极材料电子结构的DV-Xa研究

采用原子基表示的第一原理赝势方法，计算了正极材料LiMn2O4的电子结构，发现LiMn2O4的价带主要是由Mn(8)和Mn(9)的3d轨道和O(7)、O(6)、O(4)的2p轨道构成，导带主要是由Mn(8)和Mn(9)的3d轨道和O(7)的2p轨道构成．通过计算Li5Mn2C0O8的电子结构，发现在LiMn2O4中用钴离子取代16d位锰离子将使电极材料的费米能减小，放电电压降低；锂离子的净电荷增大，锂离子与氧离子的相互作用增强，可逆容量降低；同时由于价带宽度变窄，Co-O键间的相互作用比Mn-O键间的相互作用强，所以，结构稳定性增加，电极循环性能改善．     

FAAS测定锂离子电池正极材料LiMn2O4中的杂质钠

采用火焰原子吸收光谱法测定锂离予电池正极材料LiMn2O4中杂质Na的含量.综合考虑了消电离剂氯化铯、盐酸浓度、基体对测Na产生的影响,通过控制酸的浓度和在标准溶液中加入定量基体和消电离剂氯化铯来消除测定误差.由实验结果可知本方法简便易行,灵敏度和准确度高,精密度好,回收率在96.2%-103.8%之间,相对标准偏差(RSD)小于2%(n=10),能够满足锂离子电池正极材料分析的要求.     

锂离子电池掺钴正极材料电子结构的DV-Xα研究

采用原子基表示的第一原理赝势方法 ,计算了正极材料LiMn2 O4的电子结构 ,发现LiMn2 O4的价带主要是由Mn(8)和Mn(9)的 3d轨道和O(7)、O(6 )、O(4 )的 2p轨道构成 ,导带主要是由Mn(8)和Mn(9)的 3d轨道和O(7)的 2 p轨道构成 .通过计算Li5Mn7CoO8的电子结构 ,发现在LiMn2 O4中用钴离子取代 16d位锰离子将使电极材料的费米能减小 ,放电电压降低 ;锂离子的净电荷增大 ,锂离子与氧离子的相互作用增强 ,可逆容量降低 ;同时由于价带宽度变窄 ,Co-O键间的相互作用比Mn -O键间的相互作用强 ,所以 ,结构稳定性增加 ,电极循环性能改善 .     

锂离子电池相关材料的Raman光谱学研究

锂离子电池是目前综合性能最好的可充电池。本文总结我们实验室用Raman光谱学研究锂离子电池相关材料的一些结果 ,包括聚合物电解质的微结构和离子输运机制 ,低温热解碳负极材料的结构表征和锂离子在其中的嵌入 /脱出机理 ,元素替代引起正极材料LiMn2 O4的结构变化以及在充放电过程中电极 /电解质界面形成的钝化层的性质及其对电池性能的影响     

一代材料，一代电池：正极材料研究推动锂离子动力电池的升级换代

一代材料,一代电池。锂离子电池正极材料的研究不断推动着动力电池的升级换代。第一代动力电池的正极材料为锰酸锂LiMn₂O₄,其低温性能好、成本低和安全性高,但电池能量密度不够高。第二代动力电池正极材料为磷酸铁锂LiFePO₄和三元正极材料镍钴锰NCM/镍钴铝NCA。磷酸铁锂正极材料的优势是长寿命、低成本、高安全性。三元锂正极材料的特点是大容量、高能量密度、快充效率高。第三代动力电池的正极材料是高电压镍锰酸锂LiNi_0.5Mn_1.5O₄和镍酸锂LiNiO₂,主要解决第二代面临的低成本和长续航不能兼顾的问题以及更长里程问题。文章首先回顾第一、二代的锰酸锂、磷酸铁锂和三元正极材料的研究历程、优缺点及发展近况,之后介绍和展望下一代高电压镍锰酸锂和镍酸锂正极材料。     

锂离子电池正极材料Li2FeSiO4的电子结构与输运特性

采用基于密度泛函理论第一性原理方法, 研究了对称性为Pmn2₁的正交结构聚阴离子型硅酸盐Li₂FeSiO₄及其相关脱锂相LiFeSiO₄的电子结构, 并进一步采用玻尔兹曼理论对其输运性质进行计算. 电荷密度分析表明, 由于强Si–O共价键的存在使Li₂FeSiO₄晶体结构在嵌脱锂过程中始终保持稳定, 体积变化率只有2.7%. 能带结构与态密度计算结果表明, 费米能级附近的电子结构主要受Fe-d轨道中电子的影响, Li₂FeSiO₄ 的带隙宽度明显小于LiFeSiO₄, 说明前者的电子输运能力优于后者. 输运性质计算表明, 电导率在300–800 K时对温度的变化并不敏感, 同时也证明了Li₂FeSiO₄晶体的电导率大于LiFeSiO₄晶体, 与能带和态密度分析结论一致.     

微波-模板法合成锂离子电池正极材料LiMn2O4机理的光谱学研究

采用微波-PAM模板法合成了具有尖晶石结构的锰酸锂材料,利用动态红外光谱（FTIR）对该方法的反应机理进行了研究。在前驱体的制备和在LiMn2O4晶核形成过程中,由于聚丙烯酰胺与反应母体之间的弱键合作用,使其在晶粒生长过程中对LiMn2O4的团聚规律与缺陷结构起到重要调控作用。     

Mn3O4包覆对LiNi0.5Mn1.5O4正极材料界面电化学性能的提高

本文采用化学湿磨法,首次将金属氧化物Mn₃O₄包覆于LiNi_0.5Mn_1.5O₄颗粒表面,使得电极材料的电子电导率从1.53×10^-7 S/cm 提高到3.15×10^-5 S/cm. 电化学测试结果表明Mn₃O₄包覆大大提高LiNi_0.5Mn_1.5O₄正极材料的倍率性能和高温循环稳定性. 最佳包覆样品为2.6wt% Mn₃O₄包覆的LiNi_0.5Mn_1.5O₄,在10 C倍率下具有108 mAh/g的高放电容并且在55 °C下100次循环后仍有78%的容量保持率,远大于未包覆样品67%的容量保持率.     

锂离子电池LiMn1-xFexPO4(0<x<1)正极材料的制备及性能研究

本文采用固相法制备了纯相LiMn_1-xFe_xPO₄/C (x=0.2,0.4,0.6)正极材料,并用X射线衍射(XRD)和扫描电镜(SEM)进行表征,用高精度电池测试系统进行充放电和循环伏安测试.结果表明不同Mn和Fe原子比的电极材料具有很大的性能差异,其中当x=0.4时,材料具有优异的循环稳定性和较高的可逆容量.首次充电容量和放电容量分别达到141.5 mAh/g和125.7 mAh 关键词： 锂离子电池 固相法 1-xFe_xPO₄')" href="#">LiMn_1-xFe_xPO₄ 正极材料     

基于LiCo0.8M0.2O2 (M=Ni,Zr)薄膜的全固态薄膜锂电池

用射频磁控溅射结合传统退火的方法制备LiCo0.8M0.2O2 (M=Ni,Zr)阴极薄膜．X射线衍射、拉曼光谱、扫描电子显微镜等手段表征了不同掺杂的LiCo0.8M0.2O2薄膜．结果显示,700℃退火的LiCo0.8M0．2O2薄膜具有类似α-NaFeO2的层状结构．通过对不同掺杂锂钴氧阴极的全固态薄膜锂电池Li／LiPON／LiCo0.8M0.2O2的电化学性能研究表明,电化学活性元素Ni的掺杂使全固态电池具有更大的放电容量(56μAh／cm2μm),而非电化学活性元素Zr的掺杂使全固态电池具有更好的循环稳定性．     

Fabrication of Cu@MxOy (M = Cu,Mn, Co,Fe) Nanocable Arrays for Lithium‐Ion Batteries with Long Cycle Lives and High Rate Capabilities

A new strategy is reported to fabricate Cu@M_xO_y (M = Cu, Mn, Co, Fe) nanocable arrays using five‐fold twinned copper (Cu) nanowire (NW) arrays as starting materials, to promote both the cycling stability and high rate capability of M_xO_y as anodes for LIBs. Conductive Cu NW arrays were synthesized on Cu foil via chemical vapor deposition (CVD), followed by the oxidation of their surface so as to form Cu@Cu₂O nanocable arrays. The thickness of the active material (Cu₂O) on the Cu NW arrays can be tuned from 20 nm to 160 nm by simply controlling the oxidation time. Based on this accurate control, the optimal coating thickness of Cu₂O was determined to be around 35 nm. Additionally, the Cu₂O active material shell can be easily transformed to other metal oxides with even higher specific capacities via a “coordinating etching” strategy based on Pearson's principle, resulting in Cu@M_xO_y nanocable arrays (M = Mn, Co, Fe). When applied as electrodes for LIBs, these 3D electrodes show long cycle lives (over 300 cycles) and high rate capabilities.     

Ge Nanoparticles Encapsulated in Interconnected Hollow Carbon Boxes as Anodes for Sodium Ion and Lithium Ion Batteries with Enhanced Electrochemical Performance

A carbothermal reaction route to Ge nanoparticle homogeneously encapsulated hollow carbon boxes from NH₄H₃Ge₂O₆/resorcinol formaldehyde precursors is designed, using NH₄H₃Ge₂O₆ as a Ge precursor from commercial GeO₂ and NH₄OH. The Ge/C hybrid anode for sodium ion battery displays a higher Na⁺ storage capacity of 346 mA h g^?1 after 500 cycles at a current density of 100 mA h g^?1, almost approaching the theoretical capacity of Ge. Furthermore, Ge/C anode shows significantly improved electrochemical performance for Li⁺ storage, showing a higher initial Coulombic efficiency of 85.1% and a superior reversible capacity of 1336 mA h g^?1 at a high current density of 200 mA g^?1 after 150 cycles. An excellent rate capability with a capacity of 825 mA h g^?1 at a current density of 4.0 A g^?1 can be obtained based on Ge/C anodes. The enhanced electrochemical performance can be attributed to the unique microstructures of Ge/C hybrid anode. The internal void space of hollow carbon boxes can accommodate the volume expansion of Ge during lithiation or sodiation process, thus preserving the structural integrity of electrode material. The interconnected carbon shell can increase the electronic conductivity of the electrode, resulting in the high rate capability and cycling stability.     

Electrical relaxation studies of olivine type nanocrystalline LiMPO4 (M=Ni,Mn and Co) materials

The olivine type LiMPO₄ (M=Ni, Mn and Co) materials were synthesized by solution combustion technique using glycine as fuel. The structural characterizations were explored to confirm the phase formation of materials. The scanning electron microscope was used to identify the morphology of olivine materials. The local structure and chemical bonding between MO₆ octahedral and (PO₄)^3- tetrahedral groups were probed by Raman spectroscopy. Grain and grain boundaries were contributed for ion relaxation and dc conduction in olivine materials. Two orders of enhancement in ionic conductivity was observed in these olivine materials than the reported value. Among all the explored olivine samples, LiMnPO₄ showed highest enhancement in conductivity due to weak Li–O bonding and largest unit cell volume.     

Vanadium Pentoxide‐Based Cathode Materials for Lithium‐Ion Batteries: Morphology Control,Carbon Hybridization,and Cation Doping

Vanadium pentoxide (V₂O₅) is a promising cathode material for high‐performance lithium‐ion batteries (LIBs) because of its high specific capacity, low cost, and abundant source. However, the practical application of V₂O₅ in commercial LIBs is still hindered by its intrinsic low ionic diffusion coefficient and moderate electrical conductivity. In the past decades, progressive accomplishments have been achieved that rely on the synthesis of nanostructured materials, carbon hybridization, and cation doping. Generally, fabrication of nanostructured electrode materials can effectively decrease the ion and electron transport distances while carbon hybridization and cation doping are able to significantly increase the electrical conductivity and diffusion coefficient of Li⁺. Implementation of these strategies addresses the problems that are related to the ionic and electronic conductivity of V₂O₅. Accordingly, the electrochemical performances of V₂O₅‐based cathodes are significantly improved in terms of discharge capacity, cycling stability, and rate capability. In this review, the recent advances in the synthesis of V₂O₅‐based cathode materials are highlighted that focus on the fabrication of nanostructured materials, carbon hybridization, and cation doping.     

First-principles study of LiMPO4 compounds (M=Mn,Fe, Co,Ni) as electrode material for lithium batteries

The intercalation voltages of cathode materials for rechargeable lithium-ion batteries are calculated for lithium-orthophosphate oxides LiMPO₄ (M=Mn, Fe, Co and Ni) using density-functional theory within the local-density (LDA) and LDA?+?U approximations. We show that the LDA?+?U approximation is able to reproduce the experimental volumes as well as the experimentally observed magnetic structures of the lithiated and non-lithiated compounds for which LDA qualitatively fail. Moreover, we find that, using the LDA?+?U approach, the experimental evolution of the lithium intercalation voltage along the series can be reproduced accurately.     

Tin-doped spinel-related oxides of composition M3O4 (M = Mn, Fe, Co)

Tin-doped compounds of spinel-related M₃O₄ (M = Fe, Mn, Co) have been studied by ¹¹⁹Sn and ⁵⁷Fe Mössbauer spectroscopy in the temperature range of 20–600 K. The ¹¹⁹Sn Mössbauer spectra recorded down to 20 K from the non-iron-containing compounds of Co₃O₄ and Mn₃O₄ contained only doublets showing no transfer of magnetic properties from cobalt or manganese to the dopant tin ions. In contrast, the tin-doped-(FeCo)₃O₄ and (FeMn)₃O₄ gave ¹¹⁹Sn and ⁵⁷Fe Mössbauer spectra, which showed magnetic hyperfine interactions. The Curie temperature has been estimated for the former sample.     

Electronic Structure and Quadrupole Interactions in Promising Cathode Materials NaxMy(MoO4)3, M = Mn,Fe, Co,and Ni

Physics of the Solid State - The electronic structure and the magnetic properties of molybdates NaxMy(MoO4)3 (M = Mn, Fe, Co, and Ni) which are promising materials for sodium batteries have been...     

Raman and infrared spectral studies of [C(NH2)3]2MII(H2O)4(SO4)2, MII = Mn,Cd and VO

The Raman and FTIR spectra of three metal guanidinium sulfates, [C(NH₂)₃]₂M^II(H₂O)₄(SO₄)₂, (M^II = Mn, Cd and VO), are recorded. The observed spectral bands are assigned in terms of the fundamental modes of vibration of the guanidinium ions, sulfate groups and water molecules. The appearance of the sulfate tetrahedra's ν₁ and ν₂ modes in the IR spectra and the partial lifting of the ν₄ mode in the Raman spectra indicate the distortion of the SO₄²⁻ tetrahedra in the structure, so that its symmetry is lowered from T_d to C₁. The geometry of the sulfate group in guanidinium vanadyl sulfate does not deviate much from that of the average sulfate group. The distortion of the SO₄ tetrahedra is stronger in GuCds than in GuMnS. The CN₃ group in the guanidinium ion is planar (D_3h point group) in GuCdS and GuMnS, whereas it is lowered in the vanadyl compound. Furthermore, the spectral analyses show the presence of weak hydrogen bonds in the structures. Copyright © 2007 John Wiley & Sons, Ltd.