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1.
Real space renormalization group and Monte Carlo techniques are used to study the statistical mechanics of a lattice gas model of Li ordering in an intercalation battery. The dependence of the voltage on the state of charge of the battery is related to the number and types of sites available to the Li ions and to the strength and distance dependence of the Li-Li interaction. Several models are discussed and compared with the observed behaviour of LixTiS2.  相似文献   

2.
Micrometric LiMn2O4 particles are mechano-chemically modified by ball-milling to obtain a mixture of nano- and micro-scale particles. This mixture is tested as a potential active cathode material for rapid-charge Li ion batteries, and also as a model system for studying the detailed kinetics of Li intercalation/de-intercalation in such electrodes. Ragone plots recorded using galvanostatic measurements indicate enhanced power delivery characteristics of the ball-milled LiMn2O4 compared to its unprocessed counterpart. The processed material also exhibits improved resistance against electrolyte reactions and surface film formation. Due to these advantageous electrochemical attributes, the ball-milled LiMn2O4 serves as an adequately suited system for exploring certain fundamental aspects of Li intercalation in this material. Scan rate dependent slow scan cyclic voltammetry helps to identify the kinetic and diffusion controlled features of Li transport in mechano-chemically processed LiMn2O4. Electrochemical impedance spectroscopy substantiates these findings further and provides detailed kinetic parameters, including voltage dependent charge transfer resistance and diffusion coefficient of Li transport.  相似文献   

3.
汝强  李燕玲  胡社军  彭薇  张志文 《物理学报》2012,61(3):38210-038210
采用第一性原理超软赝势平面波方法计算了Sn3InSb4的嵌Li性能,得到各种嵌Li相的嵌Li形成能、理论质量比容量、体积膨胀率、能带结构、态密度和差分电荷密度等.从能量角度分析,Li在嵌入时,优先占据晶胞的四面体间隙位置,然后逐步挤出处于节点位置的Sn原子和In原子.在嵌Li过程中,材料表现出较大的体积膨胀率(11.74%-43.40%),这是导致Sn3InSb4作为Li离子电极材料循环性能差的重要原因.态密度计算表明,体系的导电性能首先随嵌Li量的增加而增加,当所有的间隙位置被Li填满,发生Sn的替换反应时,富Li态合金相的导电性反而下降.  相似文献   

4.
叶浩亮  李飞  王松林 《应用声学》2017,25(5):218-221
锂-亚硫酰氯电池作为一种免维护、高比能、长储存寿命电池,目前已经在以国防领域为代表的国民经济中得到了广泛应用;其储存寿命的考核在行业内尚属难题;通过广泛、深入地调研和对前期锂-亚硫酰氯电池储存数据的收集整理,研究了锂-亚硫酰氯电池的储存寿命影响因素及其试验评估方法;通过研究得知,锂-亚硫酰氯电池的储存寿命试验应尽早备样,若时间紧迫可通过加速试验方法;提出了通过等效储存试验时间来评估电池储存寿命及其可靠度的方法,指出当等效储存试验时间不足时,应安排样本进行容量回归分析,得出其退化规律;此外,还要对电池储存末期热性能进行分析;在以上工作基础上对电池储存寿命进行综合评估;最后,通过案例分析,进行了工程演算;为后续锂-亚硫酰氯电池储存寿命评估提供了参考。  相似文献   

5.
The intercalation of Li into UHV cleaved layered chalcogenides TiS2, TiSe2, and InSe was investigated mainly by soft x-ray photoelectron spectroscopy and related to electrochemical results by comparing work function changes to the battery voltage. The reactivity as well as the changes in electronic structure were additionally investigated. Paper presented at the 1st Euroconference on Solid State Ionics in Zakynthos, Greece, 11–18 Sept. 1994.  相似文献   

6.
An unusual sequence of phase transitions (PT) and reentrant dipole glass-like phase formation at low temperatures was found recently in KTaO3 weakly doped with Li and Nb (K0.9986Li0.0014Ta0.976Nb0.024O3) [Phys. Rev. B 63 (2001) 172]. We report on detailed low frequency (100 Hz-1 MHz) permittivity and Raman light scattering studies of similar composition, but without Li admixture, KTa1−xNbxO3 with x=0.018 (KTN1.8). The aim of the study is to answer the question if the reentrant dipole glass-like phase exists in KTN1.8 and what is the microscopic origin of this phase. A detailed study of the sharp low-temperature PT observed at TC∼27 K revealed properties inherent to the reentrant glass-type state at lower temperatures. The substitution of Nb for Ta influences the TO1 soft lattice mode and leads to PT with the long-range ferroelectric ordering. A crossover to an order-disorder polar microregion dynamics with a non-standard ε′(T) behaviour and dipole glass-like formation were found below TC (at ∼15 K), which is attributed to the randomness of the Nb distribution. A crossover to the long-range order was found under a dc bias field.  相似文献   

7.
We study the removal of the copper in Cu3Mo6S8 by the intercalation of lithium. For 0<×<1, LixCu3Mo6S8 is a single phase compound. For x?1, the copper atoms are forced out of the Mo6S8 host. We present a lattice-gas model which shows how the intercalation of Li can force the Cu out of the host.  相似文献   

8.
The diffusion process in a host structure has been studied at constant current with the cells: RuO2 composite/ LiClO4PEO/Li and RuO2 powder/LiClO4PC/Li. The effect of grain size distribution and temperature has been investigated and the diffusion coefficient for Li in RuO2 calculated along with the diffusion activation energy (0.52 eV). Results show no intercalation of PC at 25°C.  相似文献   

9.
Surface morphology in 3.5 × 3.5 μm2 area of spinel LiMn2O4, which is a typical cathode material for Li ion secondary batteries, is studied using an atomic force microscopy (AFM) with a conductive probe. Negative bias voltage is applied to the probe to attract Li+ ions toward LiMn2O4 surface during the AFM observation. Before applying the voltage (0 V), the whole LiMn2O4 surface is covered with scale-shaped grains. Under the negative voltage of 5.5 V, electric current abruptly increases, indicating Li+ ionic conduction. Simultaneously, part of the scale-shaped grains expand and flatten. Jahn-Teller phase transition, which is induced by the repulsive interaction between the Mn-eg and O-2p electrons in Li accumulated layer, is proposed as a possible origin of these results.  相似文献   

10.
This paper studies the structure and electronic properties of Li4Ti5O12, as anode material for lithium ion batteries, from first principles calculations. The results suggest that there are two kinds of unit cell of Li4Ti5O12: n-type and p-type. The two unit cells have different structures and electronic properties:the n-type with two 16d site Li ions is metallic by electron, while the p-type with three 16d Li ions is metallic by hole. However, the Li4Ti5O12 is an insulator. It is very interesting that one n-type cell and two p-type cells constitute one Li4Ti5O12 supercell which is insulating. The results show that the intercalation potential obtained with a p-type unit cell with one additional electron is quite close to the experimental value of 1.5 V.  相似文献   

11.
The effect of the cation doping on the electronic structure of spinel LiMyMn2−yO4 (M=Cr, Mn, Fe, Co and Ni) has been calculated by first-principles. Our calculation shows that new M-3d bands emerge in the density of states compared with that in LiMn2O4. Simultaneously, the new O-2p bands appear accordingly in almost the same energy range around the Fermi energy owing to the M-3d/O-2p interaction. It is found that the appearance of new O-2p bands in the lower energy position results in a higher intercalation voltage. Consequently, the origin of higher intercalation voltage in LiMyMn2−yO4 can be ascribed to the lower O-2p level introduced by the doping cation M.  相似文献   

12.
The electronic structure and band structure of olivine LiFePO4 and its virtually delithiated product FePO4 are compared based on first-principles calculations. It is found that Li intercalation mainly impacts the electronic and band structures of the Fe atom. Total static energy calculations indicate that it is more difficult for lithium to transfer in LiFePO4 than in FePO4.  相似文献   

13.
《Solid State Ionics》1987,22(4):337-344
Results are presented for low voltage discharges of lithium electrochemical cells containing layered dichalcogenides of molybdenum and tungsten. Reversible intercalation of Li at high voltages occurs only for phases with octahedrally-coordinated metal atoms but all phases decompose irreversibly at low voltages to a mixture of Mo or W and Li2X, where X is S, Se, or Te. Lithium can be removed electrochemically from these mixtures at a voltage that correlates with the free energies of formation of Li2X.  相似文献   

14.
O K‐edge and Co L‐edge near‐edge X‐ray absorption fine structure has been used to examine the cathode of an intact solid‐state lithium ion battery. The novel technique allowed for the simultaneous acquisition of partial electron yield and fluorescence yield data during the first charge cycle of a LiCoO2‐based battery below the intercalation voltage. The chemical environments of oxygen and cobalt at the surface are shown to differ chemically from those in the bulk. The present design enables a wide variety of in situ spectroscopies, microscopies and scattering techniques.  相似文献   

15.
A fabrication of all-solid-state thin-film rechargeable lithium ion batteries by sol-gel method is expected to achieve both the simplification and cost reduction for fabrication process. TiO2 thin film electrode was prepared by PVP (polyvinylpyrrolidone) sol-gel method combined with spin-coating on Li1 + xAlxGe2 − x(PO4)3 (LAGP) solid electrolyte which has wide electrochemical window. The thin film was composed of anatase TiO2 that is the most active phase for Li insertion and extraction and contacted well with LAGP substrate. In the cyclic voltammogram, a redox couple was observed at 1.8 V vs. Li/Li+ assigned to Li insertion/extraction into/from anatase TiO2, indicating that the thin film worked as electrode for lithium battery. The charge and discharge test in various charge and discharge rates revealed that the discharge process (delithiation) is thought to be faster than charge process (lithiation). It is attested that the sol-gel process, which derives both simplification and cost reduction for fabrication process, can be applied to thin film battery using LAGP solid electrolyte.  相似文献   

16.
赵亮  潘慧霖  胡勇胜  李泓  陈立泉 《中国物理 B》2012,21(2):28201-028201
This is the first time that a novel anode material, spinel Li4Ti5O12 which is well known as a “zero-strain” anode material for lithium storage, has been introduced for sodium-ion battery. The Li4Ti5O12 shows an average Na storage voltage of about 1.0 V and a reversible capacity of about 145 mAh/g, thereby making it a promising anode for sodium-ion battery. Ex-situ X-ray diffraction (XRD) is used to investigate the structure change in the Na insertion/deinsertion process. Based on this, a possible Na storage mechanism is proposed.  相似文献   

17.
We studied the electronic structure of a chemically Li-intercalated V2O5 xerogel. The technique used in the study was V 2p and O 1s X-ray absorption spectroscopy (XAS). The V ions in the as-prepared V2O5 xerogel are mostly in a pentavalent V5+ state. The spectra show that the V ions are partially reduced to V4+ and V3+ states upon Li intercalation. The results also show that low Li intercalation (x<1) affects mostly O 2p–V 3d mixed states, whereas for higher Li intercalation (x>1), this mechanism saturates and leads to Li2O formation.  相似文献   

18.
李佳  杨传铮  张熙贵  张建  夏保佳 《物理学报》2009,58(9):6573-6581
利用XRD系统地研究了石墨/Li(Ni1/3Co1/3Mn1/3)O2 18650型锂离子电池充放电过程中正负极活性材料的晶体结构和微结构的变化.已观测到,由于Li原子的脱嵌,使得LiMO2点阵参数a缩小,c增大,微应变增大,衍射强度比I104/I101I012/I101降低;此外,由于Li原子的嵌入,2H-石墨的点阵参数ac,以及微应变ε和堆垛无序度P都增加.同时,讨论了活性材料Li(Ni1/3Co1/3Mn1/3)O2和石墨在电池充放电过程中的嵌脱锂的物理机理.在充电时,正极Li(Ni1/3Co1/3Mn1/3)O2中处于(000)位的Li原子优先脱离晶体点阵,继后才是位于(2/3 1/3 1/3)和(1/3 2/3 2/3)位的Li原子离开点阵.锂嵌入石墨,优先进入碳原子六方网格面间的间隙位置,当负极的堆垛无序度达到一定值后,3R相逐渐析出.当电池满充或过充时,在六方石墨中形成LiC12和LiC6相.放电时,与上述过程相反,但并非是完全可逆的. 关键词: 锂离子电池 微结构 X射线衍射 嵌脱锂物理机理  相似文献   

19.
本文成功地合成了插层化合物Li1+xV3O8,并用X射线粉末衍射和等离子体发射光谱元素定量分析进行了鉴定。同时进行了NMR研究。在298—400K之间观察到了锂离子的运动致窄效应,并以此求得它的离子运动激活能为0.18eV。还测得该材料的室温电导率为10-3Ω-1·cm-1数量级。 关键词:  相似文献   

20.
Atomic force microscopy (AFM) has been used to characterize the structural evolution of the MoO3(010) surface during the initial stage of Li+ intercalation. Lithiation was observed in situ using model cells comprised of a single crystal MoO3 cathode, a dilute propylene carbonate (PC)-based electrolyte, and an Li metal anode. The insertion of Li+ into MoO3 results in the topotactic nucleation and growth of acicular LixMoO3 (x0.25) precipitates at the (010) surface. Because the interlayer spacing of LixMoO3 (d=7.88 Å) is greater than that of MoO3 (d=b/2=6.93 Å), the LixMoO3 precipitates expand out of the (010) surface as they grow into the MoO3 crystal along 010. The local strain associated with this expansion causes the LixMoO3 precipitates to crack parallel to the MoO3001 and 010 axes once their height exceeds approximately 20 nm. With continued Li+ intercalation, cracking becomes more prominent, and the (010) surface begins to fragment and disintegrate. Anisotropies in Li+ ion uptake and the influence of surface morphology on LixMoO3 precipitation and crack propagation are described.  相似文献   

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