改善锂硫电池循环性能的研究进展

综述了制约锂硫电池循环性能的因素和正极、负极、电解质对锂硫电池循环性能改善的影响.介绍了制约锂硫电池循环性能的主要因素:不可逆硫化锂的形成、硫正极多孔结构的失效和电解液组分与锂负极的副反应.分别介绍了改善锂硫电池循环性能的途径:合适的黏合剂、碳材料、正极制备工艺,锂负极保护技术,合理组分的电解质,电池结构与设计.并在此...     

锂硫电池的正极与负极研究进展

锂硫电池由于其理论能量密度高,理论比容量高,环境友好等特性,成为最有潜力应用于电动汽车与电子设备的能量储存介质之一。然而由于锂硫电池的硫正极绝缘性,多硫化物的溶解导致的穿梭效应和锂负极枝晶等问题,阻碍了锂硫电池的商业化应用。介绍了锂硫电池正极材料的结构改进与锂负极材料的保护,包括使用不同类型的碳材料与导电金属氧化物用于正极的导电框架,以及使用电解液添加剂,人工保护层等方式对锂负极进行保护。最后,对锂硫电池的未来发展进行了展望。     

硫基聚合物助力续航时间长、电容大的电池

<正>锂硫电池的蓄电量是目前最好的锂离子电池的4~5倍,但是在锂硫电池的商业化之路上存在很大的现实障碍。最近,研究人员证明,硫基聚合物可能是质轻、价廉、电容大的电池的有效解决方案。锂硫电池实用性不够强是因为其寿命较短。"锂电池可以持续充放电1 000多次,而锂硫电池充放电循环还不到100次其寿命就到了尽头。"亚利桑那州立大学化学家Jeffrey Pyun如是说。锂硫电池中,硫元素在负极与电解质中的锂离子发生反应,生成锂硫盐并最终沉积在电极上。这些副反应消耗负极的硫,从而降低了电池的存储容量并造成了电池的结构问题。据Pyun介绍,几个研究小组利用纳米材料捕获金属元素以防     

碳纳米管涂层提升电池性能

<正>理论上,以硫为负极的锂离子电池比目前销售的可充电电池可存储更多的能量,这意味着电动汽车和移动设备两次充电的时间间隔可相应延长。最近,德克萨斯州的研究人员表明,向电池的某个元件增加一层碳纳米管,取得的能效可与锂-硫电池相媲美。与当今最好的商业电池相比,锂-硫电池可储存5倍于其的能量。当锂离子电池充放电时,锂离子在两个电极之间移动并通过外部环路产生电流。电池负极容纳的锂离子越多,电池能够存储的能量     

Li-S电池负极材料性能提升方法综述

硫和硫化物作为负极材料相较于商业化石墨电极具有更高理论比容量的优势,然而由于其"穿梭效应"和无限扩张的体积导致锂硫电池的性能低下。本文综述了目前一些研究方法,通过改变锂硫电池的形貌、多孔结构、催化剂等方向来提高锂硫电池的性能。     

锂硫电池中的表面修饰

锂硫电池理论能量密度高(2 600 W·h/kg)、硫原料丰富、成本低,是最有发展前景的锂二次电池技术之一。然而硫以及放电产物硫化锂电导率低,电化学反应过程中生成的可溶性多硫化物的"穿梭效应"以及电池充放电过程中电极的体积效应等,影响了锂硫电池性能的发挥,阻碍了锂硫电池实用化进程。近年来,通过电极材料的设计、电极表界面的修饰以及电解液体系优化,锂硫电池的性能得到显著提升。综述了近年来锂硫电池中硫正极、隔膜和金属Li表界面修饰方面的研究进展。     

高性能锂硫电池材料的研究进展

文章对锂硫电池主要材料的改性现状做了简要的介绍,论述了近年来锂硫电池正极、负极和电解液的改性方法和作用,对相关研究进行总结并对锂硫电池的未来发展进行展望。     

分子筛SBA-15对锂硫电池电化学性能的影响

针对锂硫电池存在的主要问题,将介孔分子筛SBA-15添加在锂硫电池硫电极中,通过SBA-15的吸附作用来抑制多硫化物的穿梭效应。采用扫描电子显微镜、透射电子显微镜、氮气吸脱附测试等物理手段对材料进行表征,采用电池测试系统对电池的电化学性能进行测试。结果表明:添加1%SBA-15的SCS-1.0电池电化学性能得到明显提高,第300圈放电比容量比未添加SBA-15的SC电池的放电比容量提高200 mAh·g~(-1)左右。所以,在硫电极中添加1%SBA-15有利于锂硫电池电化学性能的提高。     

改善锂硫电池易燃特性的功能性隔膜研究进展

锂硫电池具有较高的能量密度,可在单兵电源、无人机和乘用车领域应用.锂硫电池以金属锂作为负极,使用时存在安全隐患.由于锂金属表面的不均匀性,循环过程容易生成锂枝晶,使电池内部发生短路,起火燃烧.锂硫电池的能量密度约为普通电池的3～5倍,在充放电过程中发热严重,电池本身过热容易引发电池热失控,造成起火甚至爆炸.使用功能性隔膜可以抑制电池内部短路和热失控的发生,提升锂硫电池的安全性能,可一定程度上削弱循环过程中的飞梭效应.本文综述了锂硫电池功能性隔膜改性工作的最新进展和未来的发展趋势.     

锂硫电池中抑制穿梭效应和锂枝晶的近期进展

锂硫电池具有突出的高比容量、环境友好、原材料廉价易得等特点,是未来新能源的一个选择方向。首先介绍了锂硫电池的研究背景以及放电原理,然后分别在电池的隔膜和负极2个方面叙述了抑制穿梭作用和抑制锂枝晶的最近进展,并且对未来锂硫电池的发展进行了展望。     

锂离子电池正极材料锂钒氧的制备及表征

以Li2CO3和V2O5为原料，采用固相法制备了锂离子电池正极材料LihV3O8，并通过XRD、SEM、粉末微电极循环伏安、恒流充放电及交流附抗等测试手段对其物理性能和电化学性能进行了表征。结果表明：所合成产物旱棒状，衍射特征峰与LiV3O8标准谱图基本一致，为单一物相．层状结构。产物具有较好的可逆性．初始容量为238．7mAh·g^-1，15次循环容量衰减至201．6mAh-g^-1，容量保持率为84．46％。粉末微电极循环伏安结果表明：Li^＋的嵌入脱出过程机理不同，嵌入是一个多相转变过程。计算得到材料的电导率为2．74×10^-5S．cm^-1     

Analysis of capacity–rate data for lithium batteries using simplified models of the discharge process

Simplified models based on porous electrode theory are used to describe the discharge of rechargeable lithium batteries and derive analytic expressions for the specific capacity against discharge rate in terms of the relevant system parameters. The resulting theoretical expressions are useful for design and optimization purposes and can also be used as a tool for the identification of system limitations from experimental data. Three major cases are considered that are expected to hold for different classes of systems being developed in the lithium battery industry. The first example is a cell with solution phase diffusion limitations for the two extreme cases of a uniform and a completely nonuniform reaction rate distribution in the porous electrode. Next, a discharge dominated by solid phase diffusion limitations inside the insertion electrode particles is analysed. Last, we consider an ohmically-limited cell with no concentration gradients and having an insertion reaction whose open-circuit potential depends linearly on state of charge. The results are applied to a cell of the form Li|solid polymer electrolyte|LiyMn2O4 in order to illustrate their utility.     

三元材料扣式电池测评条件的研究

以正极浆料配方、极片尺寸及充放电倍率等关键因素为研究对象,探求扣式电池在三元材料测评中的技术条件。极片进行SEM观察,并制成扣式电池,进行相关电化学测试。结果表明,PVDF用量6%,极片直径12 mm,压片压力20 MPa,充放电倍率0.2 C时,材料比容量及首次库伦效率测评结果较稳定,离散较小。     

A two-compartment cell for using soluble benzoquinone derivatives as active materials in lithium secondary batteries

In this study, soluble redox couples were used as active materials for an electrode using a newly designed two-compartment cell. In this cell, liquid electrolyte was separated by a solid electrolyte diaphragm, which prevents dissolved active materials from reaching the counter electrode. To balance the apparent current density and the apparent energy density, a porous sheet made of carbon paper as a current collector was set on the side of the positive electrode with an active material impregnated into it, and Li foil was set on the side of the negative electrode. Some soluble benzoquinone derivatives were examined by charge/discharge cycling for use as active materials of the positive electrode in lithium secondary batteries. Some of them showed specific capacities close to the theoretical values, assuming two-electron reduction. Among them, 2,5-dipropoxy-1,4-benzoquinone (DPBQ) could be cycled regardless of whether the amount used exceeded the solubility (with precipitate in the electrolyte) or not (all is dissolved). This implies that the active material reacts at the surface of the current collector in the dissolved state, and the precipitated fraction also participates by dissolution into the electrolyte. The results also suggest that a good cycle performance using our two-compartment cell requires an active material with relatively high solubility.     

无定形TiO2合成尖晶石Li4Ti5O12的性能

用无定形TiO2与Li2CO3高温固相反应合成了性能良好的"零应变"电极材料Li4Ti5O12. XRD, SEM和激光粒度分析表明,产物结晶度好,无杂质相,为纯立方尖晶石相,Li4Ti5O12颗粒呈砾石状形貌,有团聚现象,平均粒度约2.66 μm. Li4Ti5O12电极具有较宽的充放电平台,循环性能稳定. 以0.1 C电流比率恒电流充放电,首次放电容量和循环容量分别达180和150 mA·h/g. 交流阻抗谱研究发现,Li4Ti5O12不同嵌锂程度下的电导率对其电极的电化学阻抗具有较大影响,电极的Warburg阻抗曲线斜率与其荷电状态相关.     

A study on carbon coating to silicon and electrochemical characteristics of Si-C/Li cells

The aim of this paper is to study the electrochemical behavior of Si-C material synthesized by heating a mixture of silicon and polyvinylidene fluoride (PVDF) in the ratios of 5, 20, and 50 wt%. The particle size of the synthesized material was found to be increased with increase in the PVDF ratio. The coexistence of silicon with carbon was confirmed from the XRD analysis. A field emission scanning electron microscope (FESEM) study performed with the material proved the improvement in coating efficiency with increase in the PVDF ratio. Coin cells of the type 2025 were made by using the synthesized material, and the electrochemical properties were studied. An electrode was prepared by using the developed Si-C material. Si-C|Li cells were made with this electrode. A charge|discharge test was performed for 20 cycles at 0.1 C hour rate. Initial charge and discharge capacities of Si-C material derived from 20 wt% of PVDF was found to be 1,830 and 526 mAh|g, respectively. Initial charge/discharge characteristics of the electrode were analyzed. The level of reversible specific capacity was about 216mAh/g at Si-C material derived from 20 wt% of PVDF, initial intercalation efficiency (IIE), intercalation efficiency at initial charge/discharge, was 68%. Surface irreversible specific capacity was 31 mAh/g, and average specific resistance was 2.6 ohm * g.     

Electrochemical performance of chemically synthesized oligo-indole as a positive electrode for lithium rechargeable batteries

Indole monomer was chemically polymerized to produce polyindole (PI) powder for use as a positive electrode material for lithium rechargeable batteries. Although the PI obtained was an oligomer with a low molecular weight corresponding to just 3 indole units, its electrochemical properties exhibited high d.c. electric conductivity comparable to that of the highly conducting polyaniline-LiPF₆ or LiAsF₆. A charge separation mechanism was also suggested to describe charge/discharge behavior of the oligo-indole (OI) protonated and/or lithiated in the Li||OI battery. Moreover, the lithium rechargeable battery adopting the OI as a positive electrode showed good cycleability with a discharge capacity of ∼55 mAh g⁻¹, which did not decay until after more than 100 cycles.     

Use of multiple regression analysis to develop equations for predicting Li-Al/iron sulphide cell performance

A multiple regression analysis was conducted to develop predictive equations for the specific energy and specific power of Li-Al/iron sulphide cells over a wide range of cell designs and operating variables. The intent was to make these equations as general as possible such that one set of equations would predict the performance of Li-Al/FeS or Li-Al/FeS₂ cells with bicell (one positive electrode and two facing negative electrodes) or multiplate cell configurations. Data from 33 cells were used in the analysis of specific energy, and 26 cells were used to develop the specific power equation. The calculated specific energy and specific power showed good agreement with the measured values for these cells. In general, the deviation between the calculated and measured values was within ±10%. A check of the predictive capability of these equations also showed good agreement. The specific energy and specific power calculated for 14 cells not used in the regression analysis deviated by ±10% from the measured values. These equations were used to identify the most likely cell designs to meet selected electric-vehicle battery performance goals. These designs were included in an experimental programme for further performance evaluation.Nomenclature A _e limiting electrode area (cm²) - AHREFF coulombic efficiency (%) - b _i constants in multiple regression equation - CCO cell charge cut-off voltage (V) - CF charge factor (1.0 for fully charged cell, 0.5 for cell 50% discharged, 0.05 for cell discharged to a cut-off of 0.9–l.0 V) - DCO cell discharge cut-off voltage (V) - FCCF fully charged correction factor (1.0 for fully charged cell, 0.05 for any state of discharge) - FSLMUL product of FSUBL and MUL (defined below) - FSUBL calculated utilization factor of the limiting electrode (%) - i _c charge current density (A cm^–2) - i _D discharge current density (A cm^–2) - MUL theoretical specific energy factor (W h kg^–1) - NSPTHC negative-to-positive capacity ratio - OCV cell open-circuit voltage (V) - OFFEUT factor related to LiCl composition in electrolyte (%) - PF power factor (W kg^–1) - POSPIN reciprocal of the number of positive electrode plates - PPXCYC product of the number of positive electrode plates in the cell and the number of deep discharge cycles - R ² correlation coefficient - ¯R _c average cell resistance () - SP calculated cell specific power (W kg^–1) - SPECYC calculated cell specific energy (W h kg^–1) - SPEBAS calculated cell specific energy early in life (W h kg^–1) - TEMPR temperature ratio - TSUBCR thickness ratio of counter electrode and electrode separator - VFSNEG volume fraction salt in the negative electrode - VFSPOS volume fraction salt in the positive electrode - VOLT1R discharge voltage factor - VOLT2R charge voltage factor - W cell weight (kg) - X _i independent variables in regression equation - dependent variable in regression equation     

Electrochemical lithiation and compatibility of graphite anode using glutaronitrile/dimethyl carbonate mixtures containing LiTFSI as electrolyte

The compatibility of glutaronitrile (GLN) and its mixtures with dimethyl carbonate (DMC) containing lithium bis-(trifluoromethane sulfonyl) imide (LiTFSI) with graphite negative electrode was investigated. GLN/DMC/LiTFSI electrolytes’ mixtures were characterized in terms of their ionic conductivities and viscosities. Cyclic voltammetry, galvanostatic charge–discharge, and electrochemical impedance spectroscopy were performed in order to study the performances of the graphite anode in the GLN-based electrolytes. Results clearly indicate that no significant Li intercalation occurs in graphite in pure GLN, but when GLN/DMC (1:1 and 1:3 w/w) mixtures were used, the cycling ability of the electrode was improved as the coulombic efficiency reaches 98 and 99 %, respectively. Moreover, SEM images of the graphite anode indicate that after being cycled in GLN-based electrolytes, the electrode surface was homogenously covered by a Solid Layer Interface which insures a reversible lithiation of graphite anode.     

硫掺杂纳米Li2FeSiO4/C制备与电化学性能

采用固相反应法制备了 Li2FeSiO4-xSx/C (x=0,0.01,0.02,0.03)纳米正极材料。通过 X 射线 衍射（XRD）、扫描电子显微镜（SEM）、能量色散光谱仪（EDS）、X 射线光电子能谱（XPS）、拉 曼光谱（Raman）、红外吸收光谱（FTIR）及恒流充放电测试研究了材料的微观形貌、晶体结构和 电化学性能。结果表明，Li2FeSiO3.98S0.02/C 形貌呈纳米球状，平均粒径为45.38nm，纳米尺寸的粒径有利于缩短Li+的扩散途径；碳包覆抑制纳米晶粒的生长，可以增强材料的导电性；硫掺杂能扩大材料的隧道间距，加快了Li+的迁移速率。Li2FeSiO3.98S0.02/C 表现出较高的充放电比容量、优异的倍率性能以及循环稳定性，在 0.1C 下首次放电比容量高达 180.1mAhg -1，在 10C 下放电比容量为 85mAhg-1,1C 下循环 100 次后的容量保持率为 91.3%。