Thin-film lithium-ion battery derived from Li_(1.3)Al_(0.3)Ti_(1.7)(PO_4)_3 sintered pellet

Thin-film lithium-ion battery of LiMn2O4/Li1.3Al0.3Ti1.7(PO4)3/LiMn2O4 was fabricated using Li1.3Al0.3Ti1.7(PO4)3 sintered pellet as both substrate and electrolyte. Li1.3Al0.3Ti1.7(PO4)3 sintered pellet was prepared by sol-gel technique, and the thin-film battery was heat-treated by rapid thermal annealing. Phase identification, morphology and electrochemical properties of the components and thin-film battery were investigated by X-ray diffractometry, scanning electron microscopy, electrochemical impedance spectroscopy and galvanostatic charge-discharge experiments. The results show that Li1.3Al0.3Ti1.7(PO4)3 possesses a electrochemical window of 2.4 V and an ionic conductivity of 1.2 ×10-4 S/cm. With Li1.3Al0.3Ti1.7(PO4)3 sintered pellet as both substrate and solid electrolyte, the fabricated thin-film battery with an open circuit voltage of 1.2V can be easily cycled.

Lithium intercalation/de-intercalation behavior of a composite Sn/C thin film fabricated by magnetron sputtering

A tin film of 320 nm in thickness on Cu foil and its composite film with graphite of-50 nm in thickness on it were fabricated by magnetron sputtering. The surface morphology, composition, surface distributions of alloy elements, and lithium intercalation/de-intercalation behaviors of the fabricated films were characterized by X-ray diffraction （XRD）, scanning electron microscopy （SEM）, electron probe microanalyzer （EPMA）, X-ray photoelectron spectroscopy （XPS）, inductively coupled plasma atomic emission spectrometry （ICP）, cyclic voltammetry （CV）, and galvanostatic charge/discharge （GC） measurements. It is found that the lithium intercalation/de-intercalation behavior of the Sn film can be significantly improved by its composite with graphite. With cycling, the discharge capacity of the Sn film without composite changes from 570 mAh/g of the 2nd cycle to 270 mAh/g of the 20th cycle, and its efficiency for the discharge and charge is between 90% and 95%. Nevertheless, the discharge capacity of the composite Sn/C film changes from 575 mAh/g of the 2nd cycle to 515 mAh/g of the 20th cycle, and its efficiency for the discharge and charge is between 95% and 100%. The performance improvement of tin by its composite with graphite is ascribed to the retardation of the bulk tin cracking from volume change during lithium intercalation and de-intercalation, which leads to the pulverization of tin.

Lithium intercalation mechanism for β-SnSb in Sn-Sb thin films

Based on the first-principles plane wave pseudo-potential method, the electronic structure and electrochemical performance of LixSn4Sb4 （x=2, 4, 6, and 8） and LixSn12-xSb4 （x=9, 10, 11, and 12） phases were calculated. A Sn-Sb thin film on a Cu foil was also prepared by radio frequency magnetron sputtering. The surface morphology, composition, and lithium intercalation/extraction behavior of the fabricated film were characterized by scanning electron microscopy （SEM）, X-ray diffraction （XRD） and cyclic voltammetry （CV）. Lithium atoms can easily insert into and extract out of the β-SnSb cell due to the low lithium intercalation formation energy. It is found that lithium atoms first occupy the interstitial sites, and then Sn atoms at the lattice positions are replaced by excessive lithium. The dissociative Sn atoms continue to produce different Li-Sn phases, which will affect the electrode stability and lead to the undesirable effect due to their large volume expansion ratio. The calculated lithium intercalation potential is stable at about 0.7 V, which is consistent with the experimental result.

Promising Electrode and Electrolyte Materials for High-Energy-Density Thin-Film Lithium Batteries

All-solid-state thin-film lithium batteries(TFLBs)are the ideal wireless power sources for on-chip micro/nanodevices due to the significant advantages of safety,portability,and integration.As the bottleneck for increasing the energy density of TFLBs,the key components of cathode,electrolyte,and anode are still underway to be improved.In this review,a brief history of TFLBs is first outlined by presenting several TFLB configurations.Based on the state-of-the-art materials developed for lithium-ion batteries(LIBs),the challenges and related strategies for the application of those potential electrode and electrolyte materials in TFLBs are discussed.Given the advanced manufacture and characterization techniques,the recent advances of TFLBs are reviewed for pursuing the high-energy-density and long-termdurability demands,which could guide the development of future TFLBs and analogous all-solid-state lithium batteries.

Preparation of Sn nano-film by direct current magnetron sputtering and its performance as anode of lithium ion battery

Sn thin film on Cu foil substrate as the anode of lithium ion battery was prepared by direct current magnetron sputtering(DCMS). The surface morphology,composition and thickness and the electrochemical behaviors of the prepared Sn thin film were characterized by scanning electron microscopy(SEM),X-ray diffraction(XRD),inductively coupled plasma atomic emission spectrometry(ICP),cyclic voltammetry(CV) and galvanostatic charge/ discharge(GC) measurements. It is found that the Sn film is consists of pure Sn with an average particle diameter of 100 nm. The thickness of the film is about 320 nm. The initial lithium insertion capacity of the Sn film is 771 mA·h/g. The reversible capacity of the film is 570 mA·h/g and kept at 270 mA·h/g after 20 cycles.

Challenges in the Development of Film-Forming Additives for Lithium Ion Battery: A Review

Electrolytes additives are ubiquitous and indispensable in all electrochemical devices. In this sense, the principle and the classification of film-forming additives for lithium ion secondary batteries are described. The film formation mechanism and research progress of the pyrazole derivatives, organic halogenide, esters and derivatives, boron compounds and inorganic compounds are introduced. Emphasis is focused on the principles and film-forming mechanisms of each additive. The development of film-forming additives is forecasted and prospected.

Characterization and Electrochemical Properties of LiMn_2O_4 Thin Films Prepared by Solution Deposition

LiMn2O4 thin films were prepared by solution deposition using lithium acetate and manganese acetate us raw materials. The phase constitution and surface morphalogy were observed by X-ray diffraction and scanning electron microscopy. The electrochemical properties of the thin films were studied by cycilc voltammetry, charge- discharge experiments and impedance spectroscopy in 1 mol· L^-1 LiPF6 / EC- DMC solution using lithium metal as both the counter and reference electrodes. The films prepared by this method are of spinel phase. The lattice parameter increases with the annealing temperature aud annealing time. The film annealed at 750 ℃ for 30 minutes has the highest capacity of 34.5 μAh ·cm^- 2·μm^-1 , and its capacity loss per cycle is 0. 05% afrer being cycled 100 times.

Preparation and characterization of nanocrystalline SnO_2 thin film by electrodeposition technique

A novel process for preparing tin oxide thin films directly on copper foil by electrodeposition was developed. An optimal preparation technology to obtain SnOz thin films was proposed with current density of 8 mA/cm^2, the time of deposition of 120 min, the concentration of tin dichloride of 0.02 mol/L and the concentration of dissociated acid of 0. 03 mol/L. The phase identification, microstructure and morphology of the thin films were investigated by thermogravimetric analysis and differential thermal analysis, X-ray diffraction, Fourier transform infrared spectra,scanning electron microscopy and transmission electron microscopy. The as-deposited thin film was composed of SnO2·xH2O was obtained by drying at room temperature. Nanocrystalline SnO2 thin film having tetragonal structure with average grain size in the range of 8 to 20 nm and porous, uniform surface was obtained by heat-treating the as-deposited film at 400 ℃ for 2 h. Electrochemical characterization shows that SnO2 film can deliver a discharge capacity of 798 mAh/g and the SnO2 film with smooth surface and annealed at 400 ℃ for 2 h has better cycle performance than that with rough surface and annealed at 150℃ for 10 h.

Large-scale fabrication of re duce d graphene oxide-sulfur composite films for flexible lithium-sulfur batteries

The rapid development of flexible electronic devices requires the design of flexible energy-storage devices. Lithium-sulfur(Li-S) batteries are attracting much interest due to their high energy density. Therefore, flexible Li-S batteries with high areal capacity are desired. Herein, we fabricated freestanding reduced graphene oxide-sulfur(RGO@S) composite films with a cross-linked structure using a blade coating technique, followed by a subsequent chemical reduction. The porous cross-linked structure endows the composite films with excellent electrochemical performance. The batteries based on RGO@S composite films could exhibit a high discharge capacity of 1381 m Ah/g at 0.1 C and excellent cycle stability. Furthermore, the freestanding composite film possesses excellent conductivity and high mechanical strength. Therefore, they can be used as the cathodes of flexible Li-S batteries. As a proof of concept, soft-packaged Li-S batteries were assembled and remained stable electrochemical performance under different bending states.

Two-dimensional analysis of progressive delamination in thin film electrodes

By employing the two-dimensional analysis, i.e.,plane strain and plane stress, a semi-analytical method is developed to investigate the interfacial delamination in electrodes. The key parameters are obtained from the governing equations, and their effects on the evolution of the delamination are evaluated. The impact of constraint perpendicular to the plane is also investigated by comparing the plane strain and plane stress. It is found that the delamination in the plane strain condition occurs easier, indicating that the constraint is harmful to maintain the structure stability. According to the obtained governing equations, a formula of the dimensionless critical size for delamination is provided, which is a function of the maximum volumetric strain and the Poisson’s ratio of the active layer.

Electrochemical impedance spectra of V_2O_5 xerogel films with intercalation of lithium ion

Vanadium pentoxide xerogel films used for lithium rechargeable batteries were prepared from crystalline c-V2O5 by melt quenching method,then the electrochemical process of lithium intercalation into vanadium pentoxide xerogel films was simulated with an equivalent circuit model, which was derived from the mechanism of electrode reactions. Measured electrochemical impedance spectra at various electrode potentials were analyzed by using the complex non-linear least-squares fitting method. The results show that impedance spectra consist of 2 high-to- medium frequency depressed arcs and a low frequency straight line. The high frequency arc is attributed to the absorption reaction of lithium ions into the oxide film, the medium frequency arc is attributed to the charge transfer reaction at the vanadium oxide/electrolyte interface and the low frequency is characterized by a straight line with a phase angle of 45° corresponding to the diffusion of lithium ion through vanadium oxide phase. The experimental and calculated results are compared and discussed focusing on the electrochemical performance and the state of charge of the electrode. Moreover, the high consistence of the fitted values of the model to the experimental data indicates that this mathematical model does give a satisfying description of the intercalation process of vanadium pentoxide xerogel films.

Analysis of delamination in thin film electrodes under galvanostatic and potentiostatic operations with Li-ion diffusion from edge

Progressive delamination driven by Li-ion diffusion in elastic disk-like thin film electrodes of Li-ion batteries is modeled based on the cohesive model. Axisymmetric diffusion model is considered under both galvanostatic and potentiostatic operations. The effect of edge diffusion on the delamination process is evaluated. It is found that the diffusion from edge leads to an earlier delamination initiation. The edge effect is significant for active disks with a small aspect ratio, but negligible for the case of large aspect ratio. The edge diffusion is weaker in the potentiostatic operation than in the galvanostatic operation.

C/Sn复合薄膜的磁控溅射制备及其作为锂离子电池负极材料的电化学性能

采用磁控溅射的方法在铜箔上制备了C/Sn复合薄膜并将其作为锂离子电池负极材料,研究了C/Sn复合薄膜中Sn质量分数对其电化学性能的影响。研究发现,随着复合薄膜中Sn质量分数的增加,其首圈放电比容量增加,在一定范围内增加Sn质量分数,首圈库仑效率增加,但当Sn质量分数过多时其库仑效率降低。Sn质量分数分别为89.20%、91.61%、93.85%、95.81%的四种复合薄膜,在电流密度为500 mA/g时的首圈放电比容量分别为1195.4、1372.97、1574.86、1642.30 mA·h/g,首圈库仑效率分别为86.84%、87.88%、94.06%、80.66%。循环200圈后,四种复合薄膜的比容量衰减率分别为0.70%、6.13%、11.32%、18.88%。研究结果表明,当复合薄膜中Sn质量分数为89.20%时,其具有最优的倍率性能和循环稳定性能,随着复合薄膜中Sn质量分数的增加,其倍率性能及循环稳定性变差。

锂离子电池塑料-金属复合集流体的特性及制备研究进展

塑料-金属聚合物复合集流体(metallized plastic current collector,MPCC)通过减厚、减重可大幅提高电池的能量密度,且因聚合物自身绝缘、受热收缩、熔融等特性可提高电池的安全性,因此吸引了产业界研究者的诸多关注。了解聚合物基底和MPCC的特性及制备方法有利于高质量MPCC的研发,同时可促进高能量密度、高安全电池的发展,因此本文着重介绍了常用和亟待开发的聚合物的特性,阐明了目前市场生产的高质量PET、PP基复合集流体虽已应用于锂离子电池,但面临着各种挑战,例如PET的溶胀溶解反应,PP与金属层间的低黏结性等,并提出了相应的改进措施。此外,本文总结了聚合物表面沉积金属层的多种方法(磁控溅射、蒸镀、化学沉积和电镀等)的原理、优缺点和设备改良策略、注意事项,以期提高聚合物表面金属层的均匀性、一致性和导电率。最后,为提高MPCC在电池中的应用可行性,明确了MPCC未来研发的重点攻关问题,例如提高金属-聚合物界面黏结性,进一步提高电池安全性和导电率,并阐述了将来的发展趋势:功能化和精细化MPCC在电池中的应用。

塑料膜复合集流体在锂离子电池应用中的挑战与改进措施

塑料膜复合集流体(PFCC)是一种具有金属层+塑料聚合物+金属层的类三明治结构的新型电池集流体,可以提高锂离子电池的能量密度和安全性,因此受到了电池相关研究者的广泛关注。但PFCC也为锂离子电池的应用带来很多挑战,使其产业化进程缓慢。本文总结了其带来的诸多挑战,例如,聚合物-金属间结合力弱导致在聚合物层电解液浸泡时易脱层、导电性差使其过流能力下降、聚合物层易被腐蚀等,同时对其相关机理展开了详细的阐述:部分聚合物为非极性分子,与金属层间作用力弱;聚合物自身绝缘;PET易被催化解聚及热稳定性差等缺点。针对以上不足,本文系统地归纳了PFCC在锂离子电池应用技术中的发展历程,同时明确了可以通过界面工程、材料调控、加工技术和设备优化等方法、措施对其进行改进,例如:设置焊接质量的实时监控系统,建立多功能界面强化层,设计集流体内外功能性结构等,以期为PFCC的发展奠定理论基础,并推动PFCC在锂离子电池中的应用。

2,2-二甲基乙烯基硼酸电解液添加剂对锂离子电池的影响

为了提高石墨负极与电解液之间的界面稳定性,构建更加均匀稳定的SEI膜,在碳酸酯类电解液中添加了1%(质量分数)的2,2-二甲基乙烯基硼酸(DEBA)。采用恒流充放电、循环伏安法(CV)、交流阻抗法(EIS)进行电化学性能测试,同时采用扫描电子显微镜(SEM)、透射电子显微镜(TEM)、X射线光电子能谱(XPS)对循环前后的石墨电极进行了表征。研究结果表明,添加DEBA能够提高锂离子电池的放电比容量和循环稳定性,同时能够降低界面阻抗,形成更加均匀稳定的SEI薄膜。0.2 C时添加DEBA的电池首次放电比容量为343.2 mAh/g,循环300次后,放电比容量为285.4 mAh/g,容量保持率为83.2%,表现出比不含添加剂的电池更好的循环性能。

基于NTC温度传感器的锂电池内部温度监测技术研究

锂电池作为储能技术的重要载体,其安全性和可靠性备受关注。相较于电压、电流,锂电池的内部温度能够更加直观地反应其工作状态,因此温度是未来智能电池多维监测中必不可少的物理量之一。介绍了一种负温度系数(NTC)温度传感器植入到小型软包电池中进行原位温度监测的可行性研究。温度传感器通过植入工艺可以便捷地植入到锂电池内部并保证电池良好的密封性。进一步研究了锂电池工作时温度的变化特性,对后续研究电池模拟仿真的优化提供理论支撑。

SEI膜形貌与结构对锂离子电池性能的影响

固态电解质界面膜(SEI)是电解液与电极在固/液相界面上发生电化学反应后,覆盖在电极表面的钝化层,其通常形成于电池的化成阶段,具有传导离子、隔绝电子的特征。优良的SEI膜对于提高锂离子电池(LIBs)的循环寿命、安全性等具有重要意义。不同电解液体系形成的SEI膜形貌和结构各不相同,对LIBs性能具有不同程度的影响。因此,深入分析SEI膜形貌和结构与电池性能之间的构效关系很重要。本文首先综述了影响SEI膜结构和性质的因素;然后阐述了原位/非原位表征SEI膜形貌和结构的主要方法,并介绍了一种新型的电化学阻抗表征技术;最后总结了SEI膜结构对LIBs离子传输、锂沉积和界面脱溶剂化等方面的影响。通过总结SEI膜的结构与LIBs性能之间的关系,以期靶向调控SEI膜结构提升锂离子电池性能。

LiNbO3负极薄膜电化学性能及全固态薄膜锂离子电池应用

全固态薄膜锂离子电池具有易微型化与集成化等优点,因此,非常适合为微系统供电。负极对全固态薄膜锂离子电池的性能有重要影响。现有电池通常采用金属锂作为负极,然而其枝晶生长问题及低的热稳定性限制了相应电池在工业、军事等高温、高安全场合应用。为此,本文系统研究了LiNbO_(3)薄膜的电化学性能,结果表明:LiNbO_(3)薄膜呈现高比容量(410.2 mAh·g^(-1))、高倍率(30C时比容量80.9 mAh·g^(-1))和长循环性能(2000圈循环后的容量保持率为100%),以及高的室温离子电导率(4.5×10^(-8)S·cm-1)。在此基础上,基于LiNbO_(3)薄膜构建出全固态薄膜锂离子电池Pt|NCM523|LiPON|LiNbO_(3)|Pt,其展现出较高的面容量(16.3μAh·cm^(-2))、良好的倍率(30μA·cm^(-2)下比容量1.9μAh·cm^(-2))及长循环稳定性(300圈循环后的容量保持率为86.4%)。此外,该电池表现出优秀的高温性能,连续在100℃下工作近200 h的容量保持率高达95.6%。研究表明:LiPON|LiNbO_(3)界面不论在充放电循环还是高温下均非常稳定,这有助与提升全电池综合性能。