尖晶石LiMn2O4及其衍生物的电化学阻抗特性

尖晶石LiMn2O4(以下简称LMO)是锂离子电池正极材料之一，具有价格低廉，资源丰富的特点。锂离子电池的充放电过程实际上是锂离子从正极脱嵌、再嵌入正极的过程。因此Li^ 在正负极材料及电解液中的扩散性能影响着电池的电性能，通过其电化学阻抗谱可得出锂离子的扩散系数及电导率等参数。     

低共熔溶剂回收锂离子电池正极材料的研究

废旧锂离子电池不仅造成了严重的资源浪费同时还带来严重的环境污染问题。传统锂离子电池材料回收方法存在高能耗、高成本以及二次污染等不足。本文成功制备出乙二醇/氯化锌低共熔溶剂(DES),利用其对金属氧化物优秀的溶解能力,用于三元锂离子电池正极材料有价金属的回收,并分析了不同氯化锌浓度对低共熔溶剂热物性及其浸取能力的影响,对绿色环保回收三元锂离子电池正极材料提供了新的思路。     

锂离子电池中的物理问题及其研究进展

锂离子电池作为一种性能优越的新型可充放电池已经或将要在移动通信、手提式计算机和电动汽车等诸多领域获得广泛的应用 .然而与锂离子电池相关的物理问题却往往被人们忽视 .例如 ,如何从本质上来提高正极材料的体相电子电导率 ,而不是在正极活性物质中添加炭黑之类的电子导电材料 .文章将着重针对与锂离子电池相关的物理问题 ,介绍近年来的主要进展 ,以期待对锂离子电池有更深入的了解 .     

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     

电动汽车与锂离子电池

文章简要介绍了混合动力汽车、插电式混合动力汽车、纯电动汽车和锂离子动力电池及其关键材料。发展电动汽车可以大幅度降低人们对石油的依赖和改善城市空气质量。锂离子电池性能优越,为电动汽车的发展提供了支撑。近期,新一代锂离子动力电池正极材料即将走向应用,可使电动汽车里程增加一倍,材料选择和电池设计及制造工艺与电池储存能量、寿命、安全等密切相关,尊道而重德,可做出“好”电池。     

以碳粉为负极材料制备锂离子电池及电池性能测试

在能量存储技术中,锂离子电池是高能量密度的电化学电源.以碳为负极材料,涂膜制备了负极片,以锂片为正极片制备了CR2016锂离子电池,并对其性能进行了测试,分析了碳粉为锂电负极材料的特性.     

全固态锂离子电池内部热输运研究前沿

本文简要阐述了全固态锂离子电池的特点及其内部热输运研究的意义.介绍并总结了国内外与正极材料、负极材料、固态电解质,以及电极与电解质界面热输运性质相关的实验和理论工作.针对脱嵌锂过程对电极材料热导率的影响机理尚不明确,非晶态转变对电极材料热输运研究的挑战,界面热输运模型与方法不足等问题,系统梳理了全固态锂离子电池内部热输运的重要前沿科学问题.     

轴向压缩下圆柱形动力锂离子电池的性能

动力电池的安全问题制约了电动汽车的推广和发展,轴向压缩是锂离子电池的一种重要的破坏工况。通过实验方法,研究了18650锂离子电池在轴向压缩载荷下的安全性能,探讨了荷电状态分别为60%、80%、100%时电池的载荷、电压、温度的变化特征,分析了轴向压缩载荷下电池的失效过程。研究表明:轴向压缩过程中电压均出现特有的台阶式下降,极限载荷和温度骤升几乎同时发生;电池正极的凹槽结构诱导电池在靠近正极的侧面破裂。对比轴向压缩实验和径向平板压缩实验发现,动力电池轴向压缩热失控程度弱于径向平板压缩。     

固体核磁共振研究单斜磷酸钒锂的进展(英文)

在过去的二十年里，单斜型磷酸钒锂作为一种有前景的锂离子电池正极材料被广泛研究.固体核磁共振技术是一种研究原子局部环境和运动性，并能反映材料中长程/短程有序结构变化的有力表征手段，可以从多个角度满足磷酸钒锂材料的研究需求.本文从充放电机理、锂离子的迁移率和动力学、碳包覆、阳离子掺杂等方面简要介绍了固体核磁共振技术在单斜磷酸钒锂正极材料研究中的应用，同时涵盖了相关的理论计算工作.     

富锂正极材料在全固态锂电池中的研究进展

开发高能量密度、长循环寿命、低成本和高安全性的全固态锂电池是发展下一代锂离子电池的重要方向之一.富锂层状氧化物正极材料由于阴阳离子协同参与氧化还原反应,可以提供更高的放电比容量(>250 mAh/g)和能量密度(>900 Wh/kg),将其应用于全固态锂电池中有望推动锂离子电池能量密度突破500 Wh/kg的中长期目标.然而,富锂正极材料的电子导电性差、阴离子氧的不可逆氧化还原反应以及循环中的结构相变,导致该材料在电化学循环过程中存在初始库仑效率低、循环稳定性差和电压衰退等问题.此外,富锂正极材料的工作电压较高(>4.5 V vs.Li/Li⁺),使正极/电解质之间不仅面临常规的界面化学反应,释放的氧还会加剧界面的电化学反应,对正极/电解质的界面稳定性提出了更高的要求.因此,富锂正极材料的本征特性和富锂正极/电解质间严重的界面反应极大限制了富锂正极材料在全固态锂电池中的应用.本文首先详细阐述了富锂正极材料在全固态锂电池中的失效机制,其次综述了近年来富锂正极材料在不同固态电解质体系下的研究进展,最后总结和展望了富锂全固态锂电池未来的研究重点和发展方...     

Preparation of LiCoO2 cathode materials from spent lithium–ion batteries

Preparation of LiCoO₂ cathode materials from spent lithium–ion batteries are presented. It started with the reclaim/recycle of metal values from spent lithium–ion batteries, which involves the separation of electrode materials by ultrasonic treatment, acid dissolution, precipitation of cobalt and lithium, followed by the preparation of LiCoO₂ cathode materials. Co (99.4%) and Li (94.5%) were recovered from spent lithium–ion batteries. The LiCoO₂ cathode materials prepared from the reclaimed cobalt and lithium compounds showed good elecrtochemical performance. The reclaiming of cobalt and lithium has a promising outlook for the recycling of cobalt and lithium from spent Li–ion batteries, thus reducing the cost of Li–ion batteries.     

Phosphate materials for cathodes in lithium ion secondary batteries

Olivine phosphates of general formula LiMPO₄ (M=Fe, Co, Ni) were prepared and characterised in order to evaluate new potential cathode materials for secondary lithium ion batteries. The synthesis was performed by soft chemistry methods to avoid problematical and energetic expensive solid state reactions. In all the compounds no secondary phase was detected and the powder morphology was found to be suitable for cathode layers preparation. Only LiFePO₄ and LiCoPO₄ showed reversible lithium deintercalation-intercalation at 3.5 and 4.8 V vs. Li⁺/Li, respectively. The LiCoPO₄ high potential makes this compound very attractive for high energy batteries, but unfortunately its lifetime appears to be too poor. Paper presented at the Patras Conference on Solid State Ionics — Transport Properties, Patras, Greece, Sept. 14 – 18, 2004.     

Recent developments in the doping and surface modification of LiFePO4 as cathode material for power lithium ion battery

Lithium ion batteries have become attractive for portable devices due to their higher energy density compared to other systems. With a growing interest to develop rechargeable batteries for electric vehicles, lithium iron phosphate (LiFePO₄) is considered to replace the currently used LiCoO₂ cathodes in lithium ion cells. LiFePO₄ is a technically important cathode material for new-generation power lithium ion battery applications because of its abundance in raw materials, environmental friendliness, perfect cycling performance, and safety characteristics. However, the commercial use of LiFePO₄ cathode material has been hindered to date by their low electronic conductivity. This review highlights the recent progress in improving and understanding the electrochemical performance like the rate ability and cycling performance of LiFePO₄ cathode. This review sums up some important researches related to LiFePO₄ cathode material, including doping and coating on surface. Doping elements with coating conductive film is an effective way to improve its rate ability.     

Strategies to curb structural changes of lithium/transition metal oxide cathode materials & the changes' effects on thermal & cycling stability

Structural transformation behaviors of several typical oxide cathode materials during a heating process are reviewed in detail to provide in-depth understanding of the key factors governing the thermal stability of these materials. We also discuss applying the information about heat induced structural evolution in the study of electrochemically induced structural changes. All these discussions are expected to provide valuable insights for designing oxide cathode materials with significantly improved structural stability for safe, long-life lithium ion batteries, as the safety of lithium-ion batteries is a critical issue; it is widely accepted that the thermal instability of the cathodes is one of the most critical factors in thermal runaway and related safety problems.     

Synthesis and characterization of LiFePO4/3-dimensional carbon nanostructure composites as possible cathode materials for Li-ion batteries

Composites of three-dimensional (3D) carbon nanostructures coated with olivine-structured lithium iron phosphates (LiFePO₄) as cathode materials for lithium ion batteries have been prepared through a Pechini-assisted reversed polyol process for the first time. The coating has been successfully performed on nonfunctionalized commercially available 3D carbon used as catalysts. Thermal analysis revealed no phase transitions till crystallization occurred at 579 °C. Morphological investigation of the prepared composites showed a very good quality of the coating on the 3D carbon structures. A great enhancement of the crystallinity of the olivine structure and of the composites was revealed by the structural investigation performed on pure LiFePO₄ and composites after annealing at 600 °C for 10 h under nitrogen atmosphere. The cyclic voltammetry curves of the composites show well-defined peaks and smaller value of the polarization overpotential indicating an enhancement of electrode reaction reversibility compared to the LiFePO₄ phase.     

Computational screening of doping schemes for LiTi2(PO4)3 as cathode coating materials

In all-solid-state lithium batteries,the impedance at the cathode/electrolyte interface shows close relationship with the cycle performance.Cathode coatings are helpful to reduce the impedance and increase the stability at the interface effectively.LiTi2(PO4)3(LTP),a fast ion conductor with high ionic conductivity approaching 10^-3S·cm^-1,is adopted as the coating materials in this study.The crystal and electronic structures,as well as the Li^+ion migration properties are evaluated for LTP and its doped derivatives based on density functional theory(DFT)and bond valence(BV)method.Substituting part of Ti sites with element Mn,Fe,or Mg in LTP can improve the electronic conductivity of LTP while does not decrease its high ionic conductivity.In this way,the coating materials with both high ionic conductivities and electronic conductivities can be prepared for all-solid-state lithium batteries to improve the ion and electron transport properties at the interface.     

锂电池发展简史

由于具有很高的能量密度，锂金属在1958年被引入电池领域，1970年进入锂一次电池的商业研发阶段。自1990年以来，随着正极材料、负极材料与电解质的革新，可充放二次锂电池不断发展并实现商品化。如今锂电池技术仍在继续发展并将进一步改善人类生活。文章对40多年来锂电池技术发展历程进行了简单的回顾。     

Electrochemical behavior of hydrated molybdenum oxides in rechargeable lithium batteries

Oxide-hydrates of molybdenum (OHM) are investigated as 3-volt cathode materials for rechargeable lithium batteries. These materials with different water content showed a much better performance than that of MoO₃ as cathode of the rechargeable lithium battery. We report the electrochemical characteristics of Li//OHM batteries using the oxides and oxide-hydrates of molybdenum which were synthesized from molybdic acid. The oxide has a corrugated layered structure consisting of corner-shared MoO₆ octahedra. This structure provides electronic conductivity within basal layer and high lithium ion mobility between layers. The mechanism of dehydration and structural rearrangement of molybdic acid during heat treatment were studied by thermal analysis, x-ray diffraction, and Raman spectroscopy. Thermal analysis indicates a two-step dehydration and formation of orthorhombic α-MoO₃ and monoclinic ß-MoO₃. Discharge profiles and kinetics are dependent on the amount of “structural water” into the host lattice. The electroinsertion of Li ions occurs mainly in two steps in the potential range between 3.0 and 1.5 V (compositional range 0.0≤x(Li)≤1.5).