碳酸亚乙烯酯添加剂对LiFePO_4/石墨电池高温循环性能的影响（英文）

研究成膜添加剂对材料结构稳定性及LiFePO4/石墨电池高温循环性能的影响。分别测试添加和未添加碳酸亚乙烯酯(VC)的18650电池的高温循环性能,并通过充放电测试、交流阻抗、扫描电镜、X射线能量色散光谱以及拉曼光谱等方法研究VC对电池正、负材料结构的影响。结果表明:VC添加剂在提高石墨结构稳定性的同时显著抑制LiFePO4材料中的溶铁行为;此外,VC添加剂阻止电解液在负极表面还原分解及负极表面SEI膜的增厚,也阻止电解液在LiFePO4电极表面的分解;含有VC添加剂的电解液可以有效改善LiFePO4/石墨电池在高温下的循环稳定性。     

碳酸亚乙烯酯添加剂对LiFeP04／石墨电池高温循环性能的影响

研究成膜添加剂对材料结构稳定性及LiFePO4/石墨电池高温循环性能的影响。分别测试添加和未添加碳酸亚乙烯酯（VC）的18650电池的高温循环性能,并通过充放电测试、交流阻抗、扫描电镜、X射线能量色散光谱以及拉曼光谱等方法研究 VC 对电池正、负材料结构的影响。结果表明：VC 添加剂在提高石墨结构稳定性的同时显著抑制LiFePO4材料中的溶铁行为;此外,VC添加剂阻止电解液在负极表面还原分解及负极表面SEI膜的增厚,也阻止电解液在LiFePO4电极表面的分解;含有VC添加剂的电解液可以有效改善LiFePO4/石墨电池在高温下的循环稳定性。     

锰酸锂电池储存后容量衰减机理

采用商品化的LiMn2O4制作锰酸锂/石墨电池,研究其储存性能,并对储存前后的正极、负极和电解液进行表征分析。结果表明:半荷电常温储存一个月,电池容量衰减3.7%,循环性能得到改善。X射线衍射和透射电镜结果表明:LiMn2O4晶格发生收缩,正极表面形成一层固体电解质(SEI)膜。交流阻抗研究表明:正极阻抗由储存前的62.69Ω增大到储存后的84.64Ω,负极阻抗由储存前的183.1Ω增大到储存后的301Ω。红外光谱分析表明:电解液溶剂和电解质盐均不同程度地发生了分解,锰酸锂电池储存后容量衰减主要是由电极极化、Mn溶解、电解液分解、负极SEI膜增厚等原因造成。     

水溶性羧甲基壳聚糖粘结剂在锂离子电池石墨负极中的应用

将水溶性羧甲基壳聚糖(C-Cs)作为石墨负极粘结剂,通过测试首次充放电性能、循环性能和倍率性能以及循环前后形貌的变化,并与聚偏氟乙烯(PVDF)作为石墨负极粘结剂的性能进行了比较。结果表明:使用7%(质量分数)C-Cs粘结剂的石墨负极在0.5C(1C可逆比容量为372 mA·h/g)倍率下循环400个周期后,可逆比容量为312mA·h/g,10C倍率充放电测试下的可逆比容量为252 mA·h/g;经过100次循环之后,使用10%C-Cs粘结剂的石墨负极与使用PVDF为粘结剂的石墨负极相比,其交流阻抗有所降低,有助于电极比容量的提高和循环性能的改善。     

聚丙烯酸对钒电池正极热稳定性和电化学性能影响的研究。

通过原位热稳定性、紫外-可见光谱、拉曼光谱、X射线光电子能谱(XPS)、循环伏安法和充放电方法,研究了聚丙烯酸(PAA)对全钒氧化还原流电池(VRFB)正极电解液的热稳定性和电化学性能的影响。结果表明,PAA添加剂可以提高V(V)电解液的热稳定性。在室温条件下,少量的PAA添加剂能轻微的提高正极电解液的电化学性和VRFB的能量效率。此外,以PAA添加量为3%的正极电解液组装电池,该电池在50 ℃ 时表现出良好的充放电循环性能,其充电容量保持率高于没有添加PAA的电池。     

1,4-二氧六环预处理对锂电极的钝化作用

利用1,4-二氧六环对锂金属电极表面进行预处理,使之钝化,以提高电极的界面稳定性和充放电循环性能.结果表明:1,4-二氧六环可以在锂金属表面发生聚合,预先形成性能良好的SEI(Solid Electrolyte Interface)钝化膜,提高电解液中锂金属电极的界面稳定性,同时表面预处理并不会降低锂电极的动力学性能.锂电极的充放电循环效率测试和锂金属电池的循环性能测试表明:经过1,4-二氧六环表面预处理的锂金属电极与未经预处理的锂金属电极相比,无论是电极的充放电效率,还是由其所组成电池的放电性能与循环寿命都得到了较大提高.     

锂离子电池用石墨负极材料改性研究进展

石墨是目前商业化锂离子电池应用最广的负极材料,日益增长的市场需求对石墨负极材料的储锂性能提出了更高的要求。概述了锂离子电池的工作原理和石墨嵌锂机制,针对石墨负极材料理论比容量(372 mA.h/g)较低和电解液兼容性较差等问题,总结了近年来石墨负极材料的改性手段,主要分为表面改性和结构调控等2类,其中表面改性技术包括氧化和卤化处理,特点是通过调控界面化学性质,可增强石墨结构的稳定性,促进稳定SEI膜的形成,但对于石墨储锂容量的提升非常有限;结构调控包括剥层法和缺陷构筑法,特点是通过扩大石墨层间距、降低石墨维度及在石墨结构上构筑缺陷,从而增加锂离子的活性位点,提供更多锂离子扩散通道,缓解循环过程中的体积变化,改善石墨与电解液的相容性,显著提升石墨的储锂性能。最后对石墨负极材料的未来发展趋势进行了展望。     

层次孔结构双功能碳负极材料的制备及性能

在500～900℃的活化温度下,以酚醛树脂为碳源,采用模板-物理活化联合法制备系列超级电容电池用层次孔结构双功能碳负极材料。借助扫描电镜、透射电镜及比表面积测试仪分析材料的物理结构,组装模拟电容器和对锂半电池,利用恒流充放电法及循环伏安法考察其电化学行为。结果表明:制备的层次孔结构碳材料具有较大的中微孔结构和局域石墨微晶结构;在LiPF6/EC+DMC和Et4NBF4/AN两种电解液中均表现出良好的电化学性能;其中以活化温度为600℃时制备的碳材料性能最优,其锂离子半电池可逆容量达到611.2 mA.h/g(0.2C),50次循环效率为74%,6C倍率下稳定可逆容量仍高达223 mA.h/g,模拟电容器比电容高达143 F/g(0.1 A/g),且倍率性能优异。     

酞菁催化剂对镍氢电池性能的影响

研究2种酞菁类催化剂——酞菁钴、酞菁铁作为负极添加剂对Ni-MH电池充放电、电池内压及循环性能的影响。结果表明：在负极材料中加入酞菁钴、酞菁铁能够显著提高电池充放电性能,1C充电至额定容量时,电池最高电压分别较对比电池降低25 mV和31 mV;5C放电时,中值电压分别较对比电池高45 mV和51 mV。电池的循环性能得到改善,0.5C循环150次时,分别剩余额定容量的75%和83%;电池安全性得到提高,电池内压显著降低。     

锂离子电池微孔Sn-Co-C负极的制备及其性能

采用模板-电沉积法制备锂离子电池Sn-Co-C微孔负极。首先,采用聚合法制备PS球乳液。然后,再以柠檬酸、EDTA为络合剂,CoCl2、SnCl4为主盐,添加甲酸和PS球乳液的电解液中,电沉积制备Sn-Co-C微孔复合电极材料。随后采用EDS、XRD和SEM分析其元素成分、晶体结构和表面形貌。最后采用恒流充放电和交流阻抗测试其电化学性能。结果表明,电极表面的微孔可以缓解锂电池充放电过程中产生的体积变化所导致的活性物质脱落,提高循环性能和寿命。Sn-Co-C负极组成的电池首次充放电比容量分别为705.4和1105 mA.h.g-1,循环126次后充放电比容量分别为393.3和403.2 mA.h.g-1。     

Study of the electrochemical properties of a transition metallic ions modified electrode in acidic VOSO4 solution

Graphite material was used as the electrode for an all-vanadium redox flow battery, and the electrode was modified by transition metallic ions to enhance its electrochemical behavior. An porous graphite composite electrode has high specific surface area and high current density. The electrode modified by transition metallic ions has improved catalysis behavior that can catalyze the V（Ⅱ）-V（Ⅴ） redox reaction showed by cyclic voltammograms. This article studied the impedance of the modified electrode by electrochemical impedance spectroscopy （EIS）, and approved that the electrode modified by Co^2＋ and Mn^2＋ has a lower charge transfer resistance than the non-modified electrode. The effect of average particle size distribution is at lower frequencies that the slope of Warburg impedance is reduced by large particle size distribution. The voltage efficiency of the Co^2＋ modified electrode test cell is 81.5%, which is higher than that of the non-modified electrode.     

天然石墨中的嵌/脱锂离子过程

研究了锂离子在天然石墨中的嵌入 /脱出过程 ,以及电流密度对锂离子嵌入石墨过程的影响。非现场XRD结果显示 ,石墨的层间距随锂的嵌入与脱出发生先膨胀后收缩复原的变化 ;SEM结果显示 ,小电流密度下石墨表面的SEI膜较致密、均匀 ,而大电流密度下的则疏松、不均一 ;恒电流充放电测试结果显示 ,在相同的嵌锂电位下锂与微晶石墨和鳞片石墨所形成的层间化合物 (Li GICs)不完全相同 ;合理的充放电制度有利于小幅度改善材料的大电流充放电性能。     

稀土Y掺杂非晶态纳米Ni(OH)2的结构及其电化学性能研究

以Tween-80/n-C4H9OH/c-C6H12/NiSO4水溶液体系,采用微乳液快速冷冻沉淀法制备出稀土Y掺杂非晶态纳米级氢氧化镍粉体材料.采用XRD、SAED、SEM、TEM、EDS、Raman、IR,粒度分析和比表面等测试方法对所制备的粉体进行了结构形态表征,并对其充放电性能和交流阻抗谱进行测试.结果发现,适量稀土元素Y的掺入使非晶态纳米氢氧化镍的结构缺陷增多、无序性增强,平均粒度减小、比表面积增大,有利于降低其溶液电阻、电荷转移电阻和Warburg阻抗,从而提高其放电比容量.样品作为MH-Ni电池正极材料以0.2 C充放电,终止电压为1.0 V,当掺杂Y的质量分数为4%时,放电比容量达到333.3 mAh/g.     

Effects of modification on performance of natural graphite coated by SiO2 for anode of lithium ion batteries

A stable silicon dioxide film was coated on the surface of natural graphite anode by sol-gel method with Si（OCH2CH3）4, and effects of modification on performance of natural graphite were investigated. The structure and properties of graphite samples were determined by X-ray diffi＇actometry（XRD）, scanning electron microscopy（SEM）, energy-dispersive X-ray spectroscopy（EDS） and electrochemical measurements. The modified graphite shows mainly the layer structure, and silicon dioxide film is amorphous. Compared with the pure natural graphite, the modified graphite exhibits the higher specific capacity of 366 mA-h/g. After 40 charge-discharge cycles, the capacity retention ratio of the modified graphite reaches 99.55%, while that of natural graphite is only 83.04%. The results indicate that the surface modification of natural graphite by SiO2 is effective for improving the electrochemical performance of the natural graphite anode for lithium ion batteries.     

Electrochemical hydrogen absorbing properties of graphite/AB5 alloy composite electrode

Graphite is an inexpensive carbon material, but its hydrogen absorbing performance has attracted little attention. In this paper, in order to lower the cost of nickel metal-hydride (Ni-MH) battery, graphite is used as a hydrogen absorbing material in its negative electrode. The results of charge-discharge tests show that the graphite electrode has poor electrochemical hydrogen absorbing performance. The capacity of the graphite/AB₅ alloy (90 wt%) composite electrode is close to AB₅ alloy (298 mAh/g), but it has higher charge-discharge polarization and difficulty in activation. When graphite is modified with metal nickel powder by a simple ball milling process, the capacity of the composite electrode reaches to 315 mAh/g and its activation is accelerated. The results of electrochemical impedance spectroscopy (EIS) tests show that hydrogen diffusion in the modified composite electrode is more rapid than in AB₅ alloy, thereby resulting in lower charge-discharge polarization and better discharge performance at large currents.     

Effects of sodium substitution on properties of LiMn2O4 cathode for lithium ion batteries

Na-doped Li1.05Mn2O4 cathodes were synthesized using a sol-gel process.The samples were characterized by X-ray diffractometry(XRD),cyclic voltammetry(CV),electrochemical impedance spectroscopy(EIS)and charge-discharge measurements. The results show that all the samples exhibit the same cubic spinel phase structure without impurity.The lattice constant and unit cell volume decrease with increasing the sodium dopant amount.As the molar ratio of sodium to manganese(x=n(Na)/n(Mn))increases from 0 to 0.03,the initial discharge capacity of the Li1.05Mn2O4 cathodes decreases from 119.2 to 107.9 mA·h/g,and the discharge capability at large current rate and the storage performance decline dramatically,while cycling performance at room temperature and 55℃are improved.The CV and EIS studies indicate that reversibility of Li1.05Mn2O4 cathodes decreases and the electrochemical impedance increases with increasing the sodium dopant amount.     

Influence of Ti^4＋ doping on electrochemical properties of LiFePO4/C cathode material for lithium-ion batteries

To improve the performance of LiFePO4, single phase Li1-4xTixFePO4/C (x=0, 0.005, 0.010, 0.015) cathodes were synthesized by solid-state method. A certain content of glucose was used as carbon precursor and content of carbon in every final product was about 3.5%. The samples were characterized by X-ray diffraction(XRD), scanning electron microscopy observations(SEM), charge/discharge test, carbon analysis and electrochemical impedance spectroscopy(EIS). The results indicate that the prepared samples have ordered olivine structure and doping of the low concentration Ti~(4+) does not affect the structure of the samples. The electrochemical capabilities evaluated by charge-discharge test show that the sample with 1% Ti~(4+) (molar fraction) has good electrochemical performance delivering about an initial specific capacity of 146.7 mA·h/g at 0.3C rate. Electrochemical impedance spectroscopy measurement results show that the charge transfer resistance of the sample could be decreased greatly by doping an appropriate amount Ti~(4+).     

LiMn2O4 thin films derived by rapid thermal annealing and their performance as cathode materials for Li ion battery

1. Introduction Thin-film lithium-ion batteries have received considerable attention [1-4] because of their many possible applications, such as smart cards, CMOS-based integrated circuits, and microdevices [5-7]. Among the several thin films that can be used as cathode material for thin-film lithium-ion batter- ies, LiMn2O4 is one of the most studied cathode ma- terials [8-9] because of its relatively high-voltage plateau, nontoxicity, and good rechargeability. LiMn2O4 thin films have been…