Electrochemical characteristics of semi conductive silicon anode for lithium polymer batteries

In this paper, the electrochemical characteristics of semi conductive silicon thin films (n-type and p-type silicon) anodes integrated with the solid polymer electrolyte for lithium polymer batteries were investigated. The charge/discharge cycling tests revealed that the phosphorus-doped n-type silicon electrode shows the most stable cyclic performance after the 40^th cycle and still maintains a reversible specific capacity of about 2,500 mAh/g. The enhanced electrochemical performance of the doped silicon anode was attributed to the enhancement of its electrical conductivity, which was further confirmed by impedance spectroscopy and surface analysis by XPS.     

The C2H2 gas effect on the growth behavior of remote plasma enhanced CVD SiC:H film

SiC:H films were produced in a remote plasma enhanced chemical vapor deposition (RPE-CVD) system. The HMDS was chosen as the primary source gas and was fixed at constant flow rate of 10 sccm. The C₂H₂ gas input amount was varied from 3 to 200 sccm for the study of carbon effect on the film stoichiometry and bonding properties. The deposition temperature of the substrate was fixed at 400^∘C, and the plasma power was fixed at 300 W. Using auger electron spectroscopy, the depth profile of the film was investigated with C₂H₂ flow rate changes. The C₂H₂ played an important role in the transition between sp² and sp³ carbon hybridization bonds, which affected the growth behavior and properties of the films.     

不同基体对金属锂负极性能的影响

对不同基体及其上预制SEI膜后制备的扣式电池进行循环伏安、交流阻抗等电化学性能测试,以及对不同基体材料进行扫描电镜、亲锂性能等测试。结果显示,以不同材料为基体时,基体表面的粒子形貌对其上预制SEI膜和沉积金属锂的一次晶粒的形貌具有一定的诱导作用,从而影响其上预制SEI膜和沉积的金属锂的形貌,使不同基体上预制SEI膜的扣式电池的沉积/脱出锂的循环性能差异显著。当以涂炭铜箔为基体时,预制SEI膜的扣式电池的库伦效率高于99.0%,稳定循环次数高达820次,性能最优。     

过渡金属氧化物在锂离子电池中的应用

发展高性能负极材料对于推进锂离子电池进一步应用至关重要。介绍了新型过渡金属氧化物锂离子电池负极材料的主要特点及近期研究进展,综述了碳包裹过渡金属氧化物的合成制备方法及性能,并对该类负极材料的发展进行了展望。     

锂离子电池负极表面膜的研究现状

综述了锂离子电池负极材料表面固体电解质界面膜(SEI膜)的研究现状.在总结SEI膜的组成和特性、形成的机理及模型的基础上,分析了SEI膜可能的影响因素,讨论了SEI膜的质量对电池的热稳定性和可逆性特性的影响.     

Carbon tolerance effects of Sr<Subscript>2</Subscript>NiMoO<Subscript>6-δ</Subscript> as an alternative anode in solid oxide fuel cell under methane fuel condition

Sr₂NiMoO_6-δ (SNMO) with a double perovskite structure has been investigated as an alternative anode material for solid oxide fuel cells. The SNMO anode was compatible with the GDC electrolyte at the SOFC operating conditions. The SNMO anode was not stable at high temperatures and reducing atmospheric conditions, where Ni exsoluted from the SNMO double perovskite structure to form Ni nanoparticles. Ni nanoparticles provided highly electrochemically active sites in both H₂ and CH₄. Ni nanoparticles also provided chemically active sites for the pyrolysis of methane under H₂O shortage, leading to carbon deposition on the anode. To improve the cell performance, the SNMO anode was modified by a GDC thin film coating on the anode pore wall surface to increase the number of reaction sites and also accelerate the electrochemical reaction kinetics of the anode. The anode polarization resistance in CH₄ was decreased by the GDC modification from 18.39 Ωcm² to 0.55 Ωcm² at 800 °C. The 60% of the cell performance was improved by the GDC modification on the SNMO anode. The GDC-modified SNMO anode cell was stable for 100 h when CH₄ fuel was used.     

Preparation of Y-Ba-Cu-O tapes by pyrolysis of organic acid salts

High-T_C superconducting Y-Ba-Cu-O films were prepared on certain ceramic and metal substrates by pyrolysis of 2-ethylhexanoates. Only the films on MgO, yttria-stabilized zirconia (YSZ), and Ag substrates exhibited the superconducting transition above liquid nitrogen temperature. Transition temperatures (T_C) of 82, 85, and 82 K were observed in films of MgO, YSZ, and Ag substrates. The important factors in preparing superconducting films on substrates are the reactivity of the films and the substrates and the difference in their thermal expansions. The Y-Ba-Cu-O films were well suited for use with MgO, YSZ, and Ag substrates. Long superconducting tapes were produced on Ag substrate; flexible tape with a critical current density J_C of 3 · 10³ A/cm² at 77 K has now been prepared.     

Li(B)合金负极在热电池中的应用研究

研究了锂的质量百分数为61%的Li(B)合金和15%的LAN负极(Li-Ni).结果表明,Li(B)合金与LAN负极电极电位相同.Li(B)合金负极具有好的脉冲放电特性,脉冲电压ULi(B)》ULANo在大电流密度放电条件下,Li(B)合金与LAN负极都具备快速激活能力,性能相近.在各种电流密度下放电,Li(B)合金的利用率都比LAN负极高.Li(B)合金中吸附的金属锂能够全部放电,而且组成Li-B化合物纤维基体的锂有超过30%的锂也可以放电.如果负极结构设计合理,用Li(B)合金和LAN的热电池可在径向2048.2 m/s2离心力作用下正常放电.Li(B)合金的各种物理性能和抗氧化性优于LAN,Li(B)合金的相对成本只有LAN(Li-Ni)负极的60%.     

一种新型锂金属电池阳极3D碳纤维集流体

将聚偏氟乙烯(PVDF)溶于N,N-二甲基甲酰胺(DMF)和丙酮混合溶剂中,静电纺丝,并进行碳化得到碳纤维(CF),用作锂(Li)金属电池阳极三维(3D)集流体。与传统的Cu集流体比较,它能为锂提供储存空间,增加锂成核点,降低电流密度,并为锂提供传输通道,减少循环过程中的体积变化,从而抑制锂枝晶的生长,提高锂金属电池的电化学性能。利用电子扫描电镜(SEM)对其进行锂沉积实验,发现CF上锂枝晶明显减少。对其进行电池性能测试,发现基于CF的集流体与传统铜集流体相比,其电池性能得到明显改善。     

锂二次电池正极含硫复合材料的研究

采用聚丙烯腈与单质硫在一定条件下制备含硫复合材料,并利用蔗糖进一步对所得含硫材料进行碳包覆。采用XRD和SEM对该材料进行了表征。以碳包覆材料为正极活性物质,金属锂为负极制备锂二次电池,检验其充放电性能,并考察了碳包覆工艺过程对材料性能的影响。实验证明,经过碳包覆后的材料有较高的质量比容量和良好的循环稳定性。同时,通过组装硫基材料为正极、中间相碳微球材料为负极的全电池,初步考察了硫基正极新型锂电池的充放电特性。     

Molecular structure of a random copolymer film by plasma‐enhanced CVD from a mixture of cyclohexa hydrocarbons

An important issue in the polymerization of a polymer film by plasma‐enhanced chemical vapor deposition (PECVD) is how to control the polymer structure. As is generally recognized, it is extremely difficult to control the process because it is very complex. For example, various precursors in the plasma arise from fragmentation of source monomers, which can easily change by varying the plasma conditions. High‐energy electrons and ions in the plasma bombard the surface of the deposited film and affect the chemical reaction on the film. Moreover, the droplets that arise from the reactor wall by sputtering will accumulate on the film. However, if we aim to fabricate only a photonically functional polymer film, we will be able to find a solution. In this paper, we propose copolymerization from two types of monomers; one type is used as jointing materials by cracking, and the other is used as a photonic functional segment without serious deformation. This difference of action arises from a difference in the formation enthalpy. To confirm this idea, as an initial step, we copolymerized a film from a mixture of benzene (C₆H₆) as the functional segment and cyclohexene (C₆H₁₀) as the jointing material under the low radio frequency power. The deposited film consists of sp² bonding clusters surrounded by sp³ bonded (alkyl) networks. We confirmed that the sp² bonding clusters mostly belong to phenyl, with a few belonging to olefins arising from decomposed C₆H₆. In addition, the amount of sp² bonding increases proportionally with increasing ratio of C₆H₆ in the mixture, and the ratio of phenyl in the film becomes comparable to that of polystyrene. From these facts, we speculate that C₆H₁₀ acts as the jointing material and C₆H₆ as the functional segment. Additionally, we introduced tetrafluorocarbon (CF₄) to the plasma. CF₄ decomposes with a smaller energy than C₆H₁₀, and it forms mainly fluorine and CF₃ radicals. The fluorine radical pulls out hydrogen from the film and reacts to form dangling bonds in the film. Moreover, we speculate that they will terminate the dangling bonds. © 2012 Institute of Electrical Engineers of Japan. Published by John Wiley & Sons, Inc.     

纳米碳材料在锂离子蓄电池负极材料中的应用

近年来,纳米碳材料在锂离子蓄电池电极材料中的应用受到广泛的重视,目前纳米碳材料主要有纳米碳纤维(Carbonnanofibers,CNFs)和纳米碳管(Carbonnanotubes,CNTs)两种,本文对这两种纳米碳材料作为锂离子蓄电池负极材料的研究进行了综述。纳米碳材料可以显著提高锂离子蓄电池的嵌锂容量,但存在首次充放电效率不高以及电位滞后的缺点。纳米碳材料作为锂离子蓄电池负极材料的掺杂体具有很高的实用价值,这是由于纳米碳管和纳米碳纤维具有高的比表面积、高的导电和导热性以及优良的机械性能。     

Effects of sputtering pressure on the characteristics of lithium ion conductive lithium phosphorous oxynitride thin film

Lithium phosphorous oxynitride(Lipon) thin films as a lithium ion conductive electrolyte were prepared by radio frequency reactive sputtering in N₂ plasma. The properties of the amorphous Lipon solid electrolyte were investigated as a function of N₂ pressure during reactive sputtering. The ionic conductivity and the electrochemical stability of Lipon thin films improved drastically as the N₂ pressure decreased. The ionic conductivity closed to 10⁻⁶ S cm⁻¹ and obtained a stability window of 1.0–5.0 V with an N₂ pressure of 5 mTorr, where the number of nitrogen bonds between the phosphate groups were more than those formed at higher pressure. It was possible to fabricate the Li//LiCoO₂ complete thin film battery using this Lipon solid electrolyte, which exhibited excellent discharge characteristics close to the theoretical capacity (ca. 69 uAhcm⁻²−um⁻¹) and showed a considerably high rate capability.     

硅基负极材料预锂化技术研究进展

从物理预锂、化学反应预锂和电化学预锂等方面,综述硅基负极材料预锂化技术的研究进展.物理预锂包括:与金属锂粉末直接混合法,将气态的金属锂沉积在硅基负极材料或集流体上的真空热蒸发法,将金属锂负载在集流体上的电化学沉积法;化学反应预锂包括:溶液预锂法,将硅制成硅化锂的高能球磨法,将预锂化前驱体生成稳定LixSiyOz结构的高...     

多孔微晶炭的制备及储锂性能研究

将AR树脂液相炭化、高温炭化后,通过KOH活化及氢气还原制备了多孔微晶炭。采用N2物理吸附、X射线衍射(XRD)和X射线光电子能谱(XPS)等手段表征了炭化、活化及氢气还原样品的孔结构、微晶结构和表面化学性质,并通过恒电流充放电测试和循环伏安测试研究了该材料作为锂离子电池负极材料的电化学性能。研究结果表明:炭化样品首次可逆比容量为565.6 mAh/g,活化样品高达925.3 mAh/g,但循环性能欠佳;经氢气还原后首次可逆比容量仍可达684.0 mAh/g,30次循环后维持在约600 mAh/g,具有很好的循环性能。     

热解沥青碳材料锂的嵌入研究

选用三种沥青碳材料,分别测试了它们的充放电曲线和循环伏安曲线,并将第１周期放电后的样品,进行了ＩＲ、ＸＰＳ、ＸＲＤ的测试,从充放电特性、锂嵌入的深度、可逆性以及碳材料的结构等方面,对锂在该类碳材料中的嵌人机理进行了初步探讨。结果表明,热解沥青,尤其是中间相沥青在第１周期充放循环和充放可逆性上效率很高,这种热解沥青是很有前途的锂离子蓄电池的电极材料。     

Preparation and characteristics of LiCoO2 paste electrodes for lithium ion micro-batteries

The thick film electrodes (cathode) have been developed via screen printing using LiCoO₂ paste to improve the discharge capacity of lithium ion micro-batteries. The LiCoO₂ pastes were formulated using the mixtures of LiCoO₂ powder as a functional material, carbon black as a conducting agent, ethyl cellulose and terpineol as a vehicle, and Emphos PS-21A as a dispersant. Depending on the amount of carbon black, the average and maximum surface roughnesses varied from 0.54 to 1.00 μm and 6.2 to 18.7 μm respectively. The internal resistance in the paste electrodes could also be controlled to 120 KΩcm⁻² by the addition of carbon black in the pastes. The thickness of the printed film is independent of the paste composition, but it decreased from 15 to 6 μm with the increase in screen mesh number from 250 to 500. The initial specific discharge capacity of the printed cathode which was prepared using the mixture Ag-coated LiCoO₂ powder improved to 180 μAhcm⁻².     

锂离子蓄电池材料的研究现状

综述了目前锂离子蓄电池中常用正、负电极材料的特点 ,及电化学性能与结构之间的关系。正极材料包括层状结构的LiCoO2 、LiNiO2 以及尖晶石型LiMn2 O4 ;负极材料包括石墨、焦炭、硬碳等碳材料以及锡基氧化物材料。通过对材料电化学性能的比较 ,从商品化角度讨论了锂离子蓄电池电极材料研究的发展方向。     

锂离子电池碳负极材料的研究

综述了目前常用的锂离子碳负极材料的研究概况,并且按碳材料的石墨化程度不同对其进行分类,具体阐述了多种锂离子电池碳负极材料的特点及其制备方法。同时还简述了锂离子在碳材料中的几种嵌入机理,综合讨论了这几种嵌入机理的优缺点。通过对碳材料的循环伏安性质、充放电性质、电容量、可逆性及结构特征的比较,介绍了不同结构的锂离子电池碳负极材料的嵌锂特性。     

Solvothermal synthesis and electrochemical performance of rod-like V6O13 as cathode material for lithium ion battery

Belt-like V₆O₁₃ precursor was successfully synthesized via a simple solvothermal method for the first time. The heat-treatment changed its chemical composition, morphology, structure and electrochemical performance. When heat-treated at 350 °C, the product is rod-like particles, which are 0.3 μm wide and 0.4 μm–2 μm long, exhibits the best electrochemical performance. At a rate of 0.1C and in the voltage range of 1.5–4.0 V, it delivered an initial discharge capacity of 323.5 mAhg^?1. After 50 cycles, it can still sustain a discharge capacity of 267 mAhg^?1. The enhanced electrochemical performance originates from its higher total conductivity, higher lithium diffusion coefficient and better structural reversibility.