层状锂钴镍锰氧化物交流阻抗谱的研究

用交流阻抗法研究了锂离子电池结构、充电状态以及温度对层状锂钴镍锰氧化物反应动力学的影响．结果表明:与未卷绕的2032电池相比,卷绕的18650电池在高频出现了感抗．根据不同电位下的阻抗谱可以推断层状锂钴镍锰氧化物的脱锂过程分为三个阶段,2．0-2．7V为克服晶格结构作用力阶段,2．7-3．65V为锂离子多层钝化膜的形成过程,3．65-4．25V为多层钝化膜与溶液界面的双电层形成过程．温度的升高加快了电荷传递速度和锂离子扩散速度,计算得到电荷传递活化能和锂离子扩散活化能分别为20．48、48.67kJ／mol,且后者是电化学反应的控制步骤．     

锂离子电池正极材料研究进展以及水热法制备LiCoO2超细粉体

综述了近年来锂离子电池正极材料的研究情况.介绍了几种主要的锂离子二次电池正极材料,包括锂钴氧化物、锂镍氧化物、锂锰氧化物的结构、制备、电化学性能及改性方法等.并通过水热法合成获得均匀无杂相的、α-NaFeO2层状结构的HT-LiCoO2超细粉末.     

溶胶-凝胶法在锂离子电池正极材料制备中的应用与发展

分别介绍了锂钴氧化物、锂镍氧化物、锂锰氧化物、多元复合层状氧化物及磷酸铁锂的溶胶-凝胶法合成。探讨了采用不同元素掺杂来提高比容量和循环稳定性的改性方法。提出了目前溶胶-凝胶法在锂离子电池正极材料制备中存在的问题,并展望了它未来的发展趋势。     

中国锂二次电池正极材料的发展趋势和产业特点

一、锂离子电池正极材料发展对锂离子电池而言,其主要构成材料包括电解液、隔离膜、正负极材料等。一般来说,在锂离子电池产品组成成分中,正极材料占据着最重要的地位,正极材料的好坏,直接决定了最终二次电池产品的性能指标。而正极材料在电池成本中所占比例可高达40%左右。目前正极材料中,以过渡金属氧化物所表现出的性能最佳,主要有层状盐结构的锂钴氧化物(LiCoO2)、层状盐结构的锂镍氧化物(LiNiO2)以及尖晶石型(LiMn2O4)和层状盐结构(LiMnO2)的锂锰氧化物。从合成工艺上控制材料结构的规整性和稳定性是获得比能量高、循环寿命长的锂…     

一种安全、价廉并可快速充电的车用锂电池

麻省理工学院的科研人员研制出一种新型锂电池，该种新型锂电池用于电动混合动力汽车用电池组更为价廉。作为小型电力设备的动力装置，锂镍锰氧化物电池组比锂钴氧化物电池组更稳定、更安全。麻省理工研制的新型电池采用了比钴更便宜的锰和镍。     

2019-2025年全球锂电市场年复合增长率达15%

正根据国际市场研究机构Markets and Markets最新发布的报告透露,2019-2025年全球锂离子电池市场复合年增长率将达到15%,到2025年锂离子电池市场需求将从2018年的374亿美元增至980亿美元。随着新能源汽车、智能设备以及行业自动化的增长,全球对高功率和高能量密度的可靠和安全电池的需求也在不断增长。基于材料类型,锂镍锰钴电池将在预测期内以最高增长率增长。锂镍锰钴电池的能量密度是其主要优势。由于使用镍锰和钴的最佳比例,它     

锂离子电池正极材料的研究进展

综述了近年来发展起来的一些锂离子电池正极材料 ,主要包括嵌锂的层状LixMO2 结构和尖晶石型LixM2 O4 结构的过渡金属氧化物 (M =Co、Ni、Mn、Cr等 )。重点介绍了锂钴氧化物、锂镍氧化物、锂锰氧化物的性能、制备、结构以及改性方法等 ,并对纳米电极材料和其它正极材料的发展情况作了简介     

日本研究用金属粉末工艺制造稳定纳米丝

中型化学品生产商日本化学三洋公司（Nihon Kagaku Sangyo）于2010年3月1日宣布,已大量生产汽车锂离子电池用阴极材料。该公司正在开发组合镍、钴和锰的材料,也在改进其锂．镍氧化物材料。最近已将两款样品推向电池市场使汽车电池应用,并将在2011年财年中期后大规模上市。     

锰系正极材料电解液添加剂研究进展

从电极表面成膜及钝化集流体等方面,分别阐述锰酸锂、镍锰酸锂、三元、富锂锰基这4种锰系正极材料常用电解液添加剂的作用机理,综述了锰系正极材料电解液添加剂的研究进展,指出深入研究电解液复合添加剂的协同作用,有助于提高锂离子电池的性能。     

无机层状化合物的剥离技术及应用研究

从无机层状化合物构造出发,描述了不同电性无机层状化合物的结构和剥离方法.在此基础上着重介绍了层状锰氧化物的剥离过程,并利用剥离/重组技术成功合成了一系列纳米级锰氧化物功能材料,所合成的纳米级锰氧化物功能材料期待在选择性吸附剂、选择性催化剂及锂离子二次电池正极材料等方面得到广泛应用.     

AC+Li（NiCoMn）O2/Li4Ti5O12+MWCNTs混合型电容器EI北大核心CSCD

以钛酸锂(Li 4Ti 5O 12)/多壁碳纳米管(MWCNTs)复合材料为负极、活性炭(AC)/镍钴锰酸锂(Li(NiCoMn)O 2)复合材料为正极,组装成混合型电容器并研究其电化学性能。利用扫描电子显微镜(SEM),透射电子显微镜(TEM),X射线衍射仪(XRD),拉曼光谱仪(Raman),热重分析仪(TGA)对电极材料进行分析,通过恒流充放电(GCD)和交流阻抗谱(EIS)研究混合型电容器的电化学性能。结果表明:掺杂适量MWCNTs和镍钴锰酸锂可提高电容器的电化学性能。当MWCNTs质量分数为5%时,在电流密度为0.1 A/g下恒流充放电时比容量达161.5 mAh/g。在0.1~1 A/g时,最大功率密度和最大能量密度分别为993.2 W/kg和52.2 Wh/kg。5000周次恒流充放电循环后,容量保持率在92.2%左右,库仑效率仍有99.1%,展现出较高的能量密度和功率密度,并具有优异的循环性能。     

用研磨微电极研究LiMn2O4的循环伏安行为

用研磨微电极研究了尖晶石锂锰氧化物在1mol／L LiPF6／EC＋DMC＋EMC（1：1：1）电解液中的循环伏安行为，并用SEM分析了电极的表面形貌和锰元素分布．结果表明，尖晶石锂锰氧化物在研磨微电极上较在粉末微电极上稳定，嵌脱锂离子过程也更可逆．比较发现，固态法合成的尖晶石锂锰氧化物的循环稳定性较溶胶-凝胶法合成的要好，这一结果与XRD结晶度分析结果吻合，说明研磨微电极能够快速有效地评价尖晶石锂锰氧化物的循环稳定性及锂离子嵌脱过程的可逆性．     

Binder‐Free and Carbon‐Free 3D Porous Air Electrode for Li‐O2 Batteries with High Efficiency,High Capacity,and Long Life

Pt‐Gd alloy polycrystalline thin film is deposited on 3D nickel foam by pulsed laser deposition method serving as a whole binder/carbon‐free air electrode, showing great catalytic activity enhancement as an efficient bifunctional catalyst for the oxygen reduction and evolution reactions in lithium oxygen batteries. The porous structure can facilitate rapid O₂ and electrolyte diffusion, as well as forming a continuous conductive network throughout the whole energy conversion process. It shows a favorable cycle performance in the full discharge/charge model, owing to the high catalytic activity of the Pt‐Gd alloy composite and 3D porous nickel foam structure. Specially, excellent cycling performance under capacity limited mode is also demonstrated, in which the terminal discharge voltage is higher than 2.5 V and the terminal charge voltage is lower than 3.7 V after 100 cycles at a current density of 0.1 mA cm^?2. Therefore, this electrocatalyst is a promising bifunctional electrocatalyst for lithium oxygen batteries and this depositing high‐efficient electrocatalyst on porous substrate with polycrystalline thin film by pulsed laser deposition is also a promising technique in the future lithium oxygen batteries research.     

First-principles investigation of the gas evolution from the cathodes of lithium-ion batteries during the storage test

Gas evolution related to the positive electrode of charged lithium-ion batteries during the storage test was investigated using a first-principle method. The distribution of lithium during the delithiation process was simulated based on the density functional theory calculations of the energy required to remove the lithium from the surface or bulk crystal of lithium nickel cobalt manganese oxide (NCM) and lithium cobalt oxide (LCO). Lithium coverage of the surface was smaller for LCO than NCM at a highly charged state. The energy required to form an oxygen vacancy in NCM and LCO crystal was also calculated. The results showed that LCO was more apt to emit oxygen than NCM as the delithiation percentage was increased. The results suggest that the gas-generating side reactions related to the emission of oxygen would be more significant for LCO with high voltage charging. Experimental result showed a considerable portion of the gas was generated at the initial stages of storage for NCM, whereas LCO showed slow but steady gas evolution with increasing storage time. A large amount of Li₂CO₃ or LiOH on the surface of NCM appears to cause an immediate gas-generating side reaction, whereas LCO produces slow side reaction related to the emission of oxygen from the LCO material itself.     

Na+掺杂对Li3V2（PO4）3/C晶体结构及性能的影响

利用一步碳热还原法制备了Li3-xNaxV2(PO4)3/C(x=0、0.01、0.02、0.03、0.05、0.08、0.10、0.15)复合正极材料,并用X射线衍射、扫描电镜、红外光谱、循环伏安法、电化学阻抗谱和恒电流充放电技术研究了掺杂对材料结构、微观形貌、充放电性能和Li+脱出嵌入过程的影响。研究表明掺杂少量Na+不影响材料Li3V2(PO4)3的基本结构,但可在Li3V2(PO4)3中形成电子缺陷,提高晶体内部原子的无序化程度,降低极化和电荷转移电阻,从而改善材料的电化学性能。与Li3V2(PO4)3/C相比,Li2.98 Na0.02 V2(PO4)3/C在倍率为15C下的第50次放电容量提高12.1mAh/g,具有较好的倍率性能和循环性能。     

Q235碳钢在滨海盐土中腐蚀的电极过程特点

为了研究含水量对Q235碳钢在滨海盐土中腐蚀电极过程的影响,分别在10%、20%和34%含水土壤中,在±50mV极化及开路条件下对Q235碳钢的电化学阻抗谱进行了测量.实验结果表明:在低含水量(10%)时,Q235腐蚀的阴极过程主要受电荷转移电阻和结合层电阻控制,结合层对阳极过程的阻碍明显大于阴极过程;在中、高含水量(20%,34%)时,其阴极过程表现为明显的扩散控制特征,结合层主要影响阳极溶解过程,其对阴极反应的影响可以忽略不计.随含水量的增加,Q235的阳极反应电荷转移电阻逐渐降低;阴极扩散控制作用越来越明显.     

Metal properties and thin film oxidation

The dependence of thin film oxidation rates on the metal properties is discussed in terms of a surface state charge at the metal-oxide interface and a space charge layer in the growing oxide. The properties considered are the magnetic change at the Curie temperature, allotropic transformation and crystal orientation of the metal substrate. Experimental data on the direct logarithmic oxidation of iron, nickel, cobalt and copper forming p-type semiconducting oxides are analysed.     

High-Safety and High-Energy-Density Lithium Metal Batteries in a Novel Ionic-Liquid Electrolyte

Rechargeable lithium metal batteries are next generation energy storage devices with high energy density, but face challenges in achieving high energy density, high safety, and long cycle life. Here, lithium metal batteries in a novel nonflammable ionic-liquid (IL) electrolyte composed of 1-ethyl-3-methylimidazolium (EMIm) cations and high-concentration bis(fluorosulfonyl)imide (FSI) anions, with sodium bis(trifluoromethanesulfonyl)imide (NaTFSI) as a key additive are reported. The Na ion participates in the formation of hybrid passivation interphases and contributes to dendrite-free Li deposition and reversible cathode electrochemistry. The electrolyte of low viscosity allows practically useful cathode mass loading up to ≈16 mg cm⁻². Li anodes paired with lithium cobalt oxide (LiCoO₂) and lithium nickel cobalt manganese oxide (LiNi_0.8Co_0.1Mn_0.1O₂, NCM 811) cathodes exhibit 99.6–99.9% Coulombic efficiencies, high discharge voltages up to 4.4 V, high specific capacity and energy density up to ≈199 mAh g⁻¹ and ≈765 Wh kg⁻¹ respectively, with impressive cycling performances over up to 1200 cycles. Highly stable passivation interphases formed on both electrodes in the novel IL electrolyte are the key to highly reversible lithium metal batteries, especially for Li–NMC 811 full batteries.