Galvanostatic Cycling Tests Research Articles

Investigation of the Oxidative Stability of Li-Ion Battery Electrolytes Using Cathode Materials

In this study, anodic oxidation limits of Li-ion cell electrolytes are investigated against cathode materials containing various metal ions. These results are compared with inactive cell materials (PVDF/carbon black) and Pt working electrodes. The oxidative stability limits are extracted from galvanostatic cycling tests at low C-rates of (~C/100) which can be used as a measure for electrolyte decomposition limits. It is found that inactive cathode materials affect significantly the anodic decomposition limit of the electrolyte. Therefore such electrode materials can be used instead of inactive electrodes (Pt, stainless steel or glassy carbon) to investigate anodic electrolyte potential limits more reliable.

Improvement of silicon-based electrode for Li-ion batteries by formation of Si-TiB2-C nanocomposites

In an attempt to improve silicon-based electrode for lithium ion batteries, a series of core-shell-type nanocomposites, consisting of rigid, nano-sized grains of TiB2, which are covered by electrochemically active silicon layer and enclosed in outer carbon layer, were prepared by a relatively simple, two-step ball milling method. The composites, having different TiB2:C ratios, were characterized in terms of their lattice structural, microstructural and electrochemical properties, by means of X-ray diffraction, Raman spectroscopy, scanning electron microscopy, particle size distribution, transmission electron microscopy, as well as by electrochemical impedance spectroscopy and galvanostatic cycling tests. It is shown that with the assist of rigid TiB2 particles, silicon and graphite can be easily refined to nanoscale, and both become amorphous during the milling process, forming desired nanocomposites with TiB2-core/Si-shell-type grains covered and embedded in carbon. The amorphous Si, which is uniformly covering TiB2 cores, is electrochemically active, while both, C and TiB2 contribute to the improved electronic conductivity of the nanocomposites. Si-TiB2-C composite with 30mol.% of TiB2 content (STC-433) delivers the best electrochemical performance, with a high reversible capacity on the order of 660 mAh g-1 after 60cycles. A model depicting microstructural changes of the considered nanocomposites with increasing TiB2 content was elaborated, with the low ionic conductivity of titanium diboride being the limiting factor, which causes a decrease of the reversible capacity of the materials with excessive TiB2 amount.

A Novel Lithium Ion Battery Combining a Sustainable CuO-Carbon Conversion Anode with a High Voltage Li0.85Ni0.46Cu0.1Mn1.49O4 cathode

The development of novel cell configurations represents a key step towards a lithium ion batteries technology able to meet the increasing global energy demand. The search for sustainable and low cost electrode materials exhibiting high specific capacity, efficiency and stability is a longstanding goal of electrochemistry(1). In this respect, the replacement of conventional intercalation anodes with transition metal oxides reacting by conversion mechanisms is a promising, cheap approach to increase the cell specific capacity(2). Furthermore, the exploitation of cobalt-free, manganese spinel-structure materials at the cathode side is expected to overcome the problems deriving from the high cost and relatively low operating voltage of the presently most used LiCoO2 electrodes. Here we propose an alternative lithium ion battery combining an easily prepared, eco-compatible CuO-MCMB (Meso Carbon Micro Beads) conversion anode(3) (Theoretical capacity: 520 mAh g-1) with a high voltage, Li0.85Ni0.46Cu0.1Mn1.49O4 spinel-structure cathode(4) (Theoretical capacity: 146 mAh g-1), using propylene carbonate (PC), LiPF6 electrolyte solution. Both the anode, prepared by high energy ball milling, and the cathode, obtained by co-precipitation and solid state reaction, exhibit optimized morphologies that lead to good electrochemical responses in terms of stability, efficiency and rate-capability. The electrodes structures and morphologies are analyzed by X-ray diffraction and scanning electron microscopy, respectively, while their electrochemical behaviors in cell are investigated by means of potentiodinamic cycling with galvanostatic acceleration (PCGA) and galvanostatic cycling tests at different C-rates. The novel electrode combination here disclosed results in a full lithium ion battery characterized by an operating voltage of 3.4 V, a stable capacity of 90 mA h g-1 and a coulombic efficiency higher than 95% (see Figure below), with estimated gravimetric and volumetric energy densities of about 100 Wh/kg and 220 Wh/l, respectively. The rationale of this cell configuration lies in the employment of sustainable, low-cost and easily prepared electrode materials that make the battery particularly suitable for practical exploitation. (1) D. Larcher, J-M. Tarascon, Nature Chemistry, 2015, 7, 19. (2) J. Cabana, L. Monconduit, D. Larcher and M. Palacìn, Advanced Materials, 2001, 22, E170. (3) R. Verrelli, J. Hassoun, A. Farkas, T. Jacob, B.Scrosati, Journal of Material Chemistry A, 2013,1, 15329. (4) R. Verrelli, B. Scrosati, Y.-K. Sun, J. Hassoun, ACS Applied Materials & Interfaces, 2014, 6, 5206. Figure 1

Effect of Thermal Treatment of Poly(amide imide) Binder on Cycling Performance of Silicon Alloy-Based Anode for Lithium-Ion Battery

The growing demand for high-performance rechargeable lithium-ion batteries for applications such as portable electronic devices, electric vehicles and energy storage systems requires remarkable improvement in the energy density. It has led to the search for advanced materials with high theoretical specific capacities, which should be abundantly available for large-scale applications. Silicon-based anode materials with high theoretical capacity, low reduction potential and low cost satisfy these requirements for next-generation lithium-ion batteries. However, the silicon materials undergo large volume changes during the alloying/de-alloying reaction, resulting in pulverization of the electrode. In addition, the large volume expansion results in the continuous breakdown and formation of solid-electrolyte interphase (SEI) layer during the repeated cycling. To mitigate the volume change, many studies have been carried out by different approaches such as fabricating thin films, reducing particle size, employing Si alloy materials and using strong binder. It is well known that binders are critical to maintain the electrode structure and capacity retention. Different binders for Si-based anodes developed to date include carboxymethyl cellulose (CMC), poly(acrylic acid) (PAA), poly(vinyl alcohol) (PVA), poly(amide imide)(PAI) and polyimide (PI). Among them, thermally-treated PAI has high mechanical strength and good adhesion, enhancing the electric contact with current collector. In this study, we report electrochemical characterization of Si alloy materials with thermally-treated PAI as a binder. Furthermore, we analyzed binding mechanism of PAI, with changing heat treatment temperature. A detailed investigation and evaluation of cycling performances are performed by XPS, FT-IR, electrochemical impedance spectroscopy, peel test and galvanostatic cycling test.

High Performance TiP2O7 Based Intercalation Negative Electrode for Aqueous Lithium-Ion Batteries Via a Facile Synthetic Route

Combining high energy mechanical alloying with intimate carbon coating has proven effective in improving electrochemical performance of polyanion-based materials (1, 2). Ball milling with intimate carbon helps to prepare a homogenous mixture of precursors and reduce particle size during following thermal treatment (3, 4). In addition, this combination can decrease the thermal treatment time needed (5). In this study, we demonstrated TiP2O7/graphite prepared by high energy mechanical alloying combined with intimate carbon coating has superior cycling performance in aqueous lithium-ion electrolyte. The TiP2O7/graphite composite material was prepared by an intensive mechanical mixing solid state synthesis method at 700°C. Physical properties were characterized via powder X-ray diffraction, Rietveld refinement, SEM, BET and TGA. Electrochemical performance was evaluated in both a three electrode test setup and two electrode coin cells via cyclic voltammetry and galvanostatic cycling tests. The TiP2O7/Graphite composite demonstrates excellent cycling performance in 1M Li2SO4 when matched with LiMn2O4 as a positive electrode: when cycled at C/2 for 150 cycles, the capacity retention is over 91% with coulombic efficiencies exceeding 99%. The initial discharge capacity obtained at a C/10 rate is 91mAh/g which was about 75% of theoretical capacity 121mAh/g. Reference: 1. W. Wu, A. Mohamed and J. F. Whitacre, Journal of The Electrochemical Society, 160, A497 (2013). 2. W. Wu, J. Yan, A. Wise, A. Rutt and J. F. Whitacre, Journal of The Electrochemical Society, 161, A561 (2014). 3. J.-K. Kim, G. Cheruvally, J.-W. Choi, J.-U. Kim, J.-H. Ahn, G.-B. Cho, K.-W. Kim and H.-J. Ahn, Journal of Power Sources, 166, 211 (2007). 4. J.-K. Kim, J.-W. Choi, G. Cheruvally, J.-U. Kim, J.-H. Ahn, G.-B. Cho, K.-W. Kim and H.-J. Ahn, Materials Letters, 61, 3822 (2007). 5. L.-X. Yuan, Z.-H. Wang, W.-X. Zhang, X.-L. Hu, J.-T. Chen, Y.-H. Huang and J. B. Goodenough, Energy & Environmental Science, 4, 269 (2011). Figure 1

Flake structured SnSbCo/MCMB/C composite as high performance anodes for lithium ion battery

SnSbCo/MCMB/C composite with flake structure were prepared by stepwise synthesis method. Firstly, SnSbCo nanoparticles were fabricated by co-precipitation, and then nanosized SnSbCo alloy were embedded in mesocarbon microbeads (MCMB) by ball-milling to synthesize primitive SnSbCo/MCMB hybrids, followed by carbonization of phenolic resin to produce an outer layer of carbon coating. The crystal structure, morphology and electrochemical properties of the SnSbCo/MCMB/C composite were evaluated by X-ray diffraction (XRD), Raman spectroscopy, scanning electron microscopy (SEM), transmission electron microscopy (TEM) and galvanostatical cycling tests. Compared with bare SnSbCo alloy and SnSbCo/MCMB hybrids, the efficiently enhanced electrochemical performance of SnSbCo/MCMB/C composite were mainly ascribed to the improved electron conductivity and volume buffering effect provided by the amorphous carbon coating. The resultant SnSbCo/MCMB/C composite delivered an initial discharge capacity of 848 mAh g−1 under 100 mA g−1, with a good capacity retention of 85.6% after 70 cycles. The composite also exhibited excellent rate capability of 603 mAh g−1 and 405 mAh g−1 at the current density of 200 mA g−1 and 1000 mA g−1, respectively.

Synthesis of SnO Novel Cabbage Nanostructure and Its Electrochemical Property as an Anode Material for Lithium Ion Battery

The novel 3D SnO cabbages self-assembled by nanosheets were successfully synthesized via template-free hydrothermal growth method under facile conditions. The XRD results manifest that the as-prepared SnO is tetragonal phase. The TEM and HRTEM results show that the cabbage nanosheets are polycrystalline structure consisted of considerable single-crystalline nanoparticles. Two typical Raman modes A1g=210 and Eg=112 cm-1 of SnO are observed by Raman spectroscopy. Moreover, galvanostatic cycling tests has been performed using the SnO cabbages as anode material of lithium ion battery and the electrochemical results suggest that the synthesized SnO cabbage structures are a promising anode material for lithium ion batteries. Keywords—Hydrothermal process, lithium ion battery, Raman spectroscopy, stannous oxide.

Surface Modification of Silicon-Based Alloy Materials for Lithium-Ion Battery Applications

Lithium-ion batteries have been considered as a promising power source for electric vehicles and energy storage systems, due to their high energy density and long cycle life. In order to further increase the energy densities of lithium-ion batteries, it is essential to improve the specific capacity of active electrode materials. It has been well known that the silicon-based anode materials have an extremely high theoretical capacity. However, the main problem of silicon-based anode materials is high volume expansion during cycling, which leads to the loss of electrical contacts and poor capacity retention. To solve these issues, many studies have been carried out in terms of thin film, nanostructure, alloy and composites. The capacity fading is known to be closely related to the interfacial instability of the Si-based electrodes. In this study, we report synthesis and electrochemical characterization of Si-based alloy materials for high energy density lithium-ion batteries. Furthermore, we modified their surface to form stable interfacial layer and obtain good capacity retention. Their interfacial studies and cycling performances are investigated by electrochemical impedance spectroscopy, XPS, FE-SEM, HR-TEM and galvanostatic cycling test.

Three-dimensional nanoporous and nanopillar composite Cu-Sn electrode for lithium-ion battery

A novel three-dimensional nanostructured, namely nanoporous and irregular nanopillar, composite Cu-Sn anode material for lithium-ion batteries was synthesized by directly oxidizing copper foil slightly in air and deoxidizing under H2/Ar atmosphere. Following that, Sn layer was deposited on as-prepared Cu substrate by the direct current sputtering technique. The morphology, constituent, and electrochemical performance of the obtained samples were characterized by field emission scanning electron microscope, X-ray diffraction, energy-dispersive X-ray spectrometer, and galvanostatic cycling test. The as-prepared Cu-Sn electrode (deposition time 10 min) exhibits a stable coulombic efficiency around 95 % over 50 cycles. The 50th specific capacity is 590 mA h/g at the current of 0.3 C, and at the high rate of 12 C, it exhibits 376 mA h/g which shows a high specific capacity and remarkable rate performance as an anode for lithium-ion batteries. The special 3D nanostructure, herein, can not only effectively offer enough space to accommodate large volume change but also act as structural reinforcement during electrochemical reaction. The simple fabrication approach of this novel nanostructure can be further extended to other anode materials with remarkable electrochemical property.

Mixed Oxides, (Ni1–xZnx)Fe2O4 (x = 0, 0.25, 0.5, 0.75, 1): Molten Salt Synthesis, Characterization and Its Lithium-Storage Performance for Lithium Ion Batteries

We prepared solid solutions based on Ni, Zn, and Fe oxides to be used as nanomaterials for anodes of Li-ion batteries. The materials were synthesized using molten salt method with KCl as the molten salt. The prepared nanomaterials (Ni1–xZnx)Fe2O4 (x = 0, 0.25, 0.5, 0.75, 1) were subsequently characterized by scanning electron microscopy (SEM), X-ray diffraction (XRD), the Brunauer–Emmett–Teller surface and density methods. Cyclic voltammetry (CV) and galvanostatic cycling tests were then conducted to understand the lithium storage performance of the electrodes. Electrochemical impedance spectroscopy (EIS) was also performed to analyze the kinetics of our electrodes and other characteristics of the battery cell. The electrochemical properties of prepared compounds showed reversible capacities (mAh/g) of 706, 819, 603, 781, 637 for x = 0, 0.25, 0.5, 0.75, and 1 at the end of the 50th cycle.

High Performance TiP2O7 Based Intercalation Negative Electrode for Aqueous Lithium-Ion Batteries via a Facile Synthetic Route

A composite TiP2O7/amorphous carbon material (C-TiP2O7) was prepared by an intensive mechanical mixing/solid-state synthesis method at 800°C. Physical properties were characterized via powder X-ray diffraction, Rietveld refinement, SEM, BET and TGA. Electrochemical performance was evaluated in both a three electrode test setup and two electrode coin cells via cyclic voltammetry, electrochemical impedance spectroscopy and galvanostatic cycling tests. The C-TiP2O7 composite demonstrated excellent cycling performance in 1 M Li2SO4 when matched with LiMn2O4 as a positive electrode: when cycled at C/2 for 150 cycles, the capacity retention is over 91% with coulombic efficiencies exceeding 99%. The initial discharge capacity obtained at a C/10 rate is 91 mAh/g which is about 75% of theoretical capacity 121 mAh/g. The apparent diffusion coefficient of C-TiP2O7 composite calculated from cyclic voltammetry result is 3.5*10−15 cm2/s.

Facile hydrothermal synthesis of NiMoO4@CoMoO4 hierarchical nanospheres for supercapacitor applications.

A novel binder-free electrode material of NiMoO4@CoMoO4 hierarchical nanospheres anchored on nickel foam with excellent electrochemical performance has been synthesized via a facile hydrothermal strategy. Microstructures and morphologies of samples are characterized by X-ray diffraction (XRD), Raman, scanning electron microscopy (SEM), transmission electron microscopy (TEM), energy dispersive spectroscopy (EDS) and X-ray photoelectron spectroscopy (XPS). Besides, the effect of Ni/Co molar ratios of raw materials on electrochemical behaviors is also investigated by cyclic voltammetry, galvanostatic charge-discharge measurements, cycling tests and electrochemical impedance spectroscopy methods. Remarkably, the resulting NiMoO4@CoMoO4 hierarchical nanospheres with a Ni/Co molar ratio of 4 : 1 exhibit greatly enhanced capacitive properties relative to other components and display a high specific capacitance of 1601.6 F g(-1) at the current density of 2 A g(-1), as well as better cycling stability and rate capability. Moreover, a symmetric supercapacitor is constructed using NiMoO4@CoMoO4 nanospheres as the positive and negative electrodes with one piece of cellulose paper as the separator, which shows good electrochemical performance. Such enchanced capacitive properties are mostly attributed to the synergistic effect of nickel and cobalt molybdates directly deposited on the conductive substrate and their novel hierarchical structure, which can provide pathways for fast diffusion and transportation of ions and electrons and a large number of active sites. The results imply that the NiMoO4@CoMoO4 hierarchical nanospheres could be promising candidates for electrochemical energy storage.

Electrochemical Performance of Lithium-Ion Hybrid Supercapacitors based on Activated Carbon and Nanoplatelet Li4Ti5O12 Insertion Electrode Synthesized by Nanoscission Technique

ABSTRACTElectrochemical performance of hybrid supercapacitor (HSC) utilizing surface sculpted Li4Ti5O12 (LTO) insertion electrode having nanoplatelet-like morphology and activated carbon (AC) electrode is investigated for energy storage application. Cyclic voltammetry (CV) at variable scan rates 0.5 to 60 mV.s-1 in the 0-3.2 V range show pseusocapacitive behavior and fast rate of current change indicating rapid Faradaic kinetics. Nyquist impedance study show charge transfer resistance due to kinetic effects of electron transfer and Li+ de-intercalation process at the LTO anode. Low capacity (0.2 C-1C) charge-discharge (CD) curves show high Coulomb efficiency with marginal reduction at high 5-10 C rates due to irreversibility of adsorbed PF6 anions at the electrolyte-AC interface. Galvanostatic CD cycling tests over 50 cycles at different C-rates show decline in storage capacity due to electrode polarization effects. Reduction, broadening and shift of the Raman line at 678 cm-1 from Ti-O bonds in TiO6 octahedra after cycling indicates Li insertion reactions in functioning of hybrid supercapacitor. The hybrid supercapacitor cells have shown energy density, 29 Wh.kg-1 and power density, 350 W.kg-1.

Enhanced electrochemical performance of nanosheet ZnO/reduced graphene oxide composites as anode for lithium-ion batteries

Abstract The ZnO/reduced graphene oxide (rGO) composites were deposited directly on nickel foam current collectors by electrostatic spray deposition technique. The morphology and crystal structure of as-deposited samples were characterized by scanning electron microscopy and X-ray diffraction, respectively. Their electrochemical properties were investigated by galvanostatic cycling and cyclic voltammograms tests. The electrochemical measurement results showed that ZnO/rGO composite films possessed a high and stable specific capacity. After rate capability test for 200 cycles, the ZnO/rGO composites still exhibited a specific capacity of 360 mAh g−1 on average at current density of 0.2 A g−1. The enhanced electrochemical performances of ZnO/rGO composite films might be derived from nano-enabled structures and enhanced kinetics by introduction of reduced grapheme oxides.

A lithium ion battery exploiting a composite Fe2O3 anode and a high voltage Li1.35Ni0.48Fe0.1Mn1.72O4 cathode

In this paper we report a new lithium ion battery (LIB) consisting of a conversion-type, high capacity Fe2O3–Meso Carbon Micro Beads (MCMB) composite anode and a high voltage, Li1.35Ni0.48Fe0.1Mn1.72O4 cathode, prepared by using facile, low cost synthetic pathways. These electrodes have been characterized by a series of techniques including scanning and transmission electron microscopy, X-ray diffraction analysis, potentiodynamic cycling with galvanostatic acceleration (PCGA) and galvanostatic cycling tests in lithium cells at different C-rates. The results show that the Fe2O3–MCMB anode benefits by a composite, sub micrometric morphology and by a stable specific capacity ranging from 800 to 600 mA h g−1, evolving around 0.9 V, while the Li1.35Ni0.48Fe0.1Mn1.72O4 cathode is formed by an agglomeration of micrometric crystals delivering a reversible capacity of about 115 mA h g−1 at a 4.7 V high voltage. The combination of the Fe2O3–MCMB anode with the Li1.35Ni0.48Fe0.1Mn1.72O4 cathode leads to a complete lithium ion battery having an operating voltage of about 3 V, a high coulombic efficiency and a stable capacity of about 100 mA h g−1, which translates into in a theoretical energy density of about 300 Wh kg−1.

Three-dimensional lamination-like P2-Na2/3Ni1/3Mn2/3O2 assembled with two-dimensional ultrathin nanosheets as the cathode material of an aqueous capacitor battery

Three-dimensional (3D) lamination-like transition metal oxide Na2/3Ni1/3Mn2/3O2, assembled with two-dimensional (2D) ultrathin nanosheets, is successfully synthesized using a combined co-precipitation and thermal treatment method. The material was investigated, for the first time, as the positive electrode material of an aqueous Na-ion capacitor battery. The structure and morphology of the as-prepared material are systematically characterized by X-ray diffraction, scanning electron microscopy, energy-dispersive X-ray spectrometry and X-ray photoelectron spectroscopy. Its performance for Na-ion intercalation/deintercalation in a 1molL−1 Na2SO4 aquesous electrolyte is evaluated by cyclic voltammetry, galvanostatic cycling test and electrochemical impedance spectroscopy. The Na2/3Ni1/3Mn2/3O2 electrode is charged between -0.8∼1.0V (vs. SCE) with no water decomposed. The reversible capacity of the electrode reached 157mAhg−1 at 0.05C and retained to be 84mAhg−1 and 51mAhg−1 at 0.20C and 0.50C, respectively. After 80 cycles at 0.20C, the specific capacity of Na2/3Ni1/3Mn2/3O2 remains to be 42mAhg−1. The wide charge/discharge potential range and the high capacity reveal that the 3D lamination-like P2-Na2/3Ni1/3Mn2/3O2 assembled with 2D ultrathin nanosheets can be a promising cathode material for low-cost aqueous Na-ion capacitor battery.

Preparation of Ni3B2O6 nanosheet-based flowerlike architecture by a precursor method and its electrochemical properties in lithium-ion battery

A novel flower-like nickel borate of Ni3B2O6 nanostructure was prepared through a hydrothermal treatment and sequential thermal decomposition of precursor without employing any template or surfactant. All the samples were characterized by XRD, IR, XPS, TG–DTA, nitrogen adsorption, SEM and TEM. The flower-like Ni3B2O6 nanostructure was self-assembled by nanosheets with the thickness of about 40 nm. The electrochemical properties in lithium-ion battery of flower-like Ni3B2O6 nanostructure were studied by the cyclic voltammetry, galvanostatic cycling test, and electrochemical impedance spectroscopy, which showed it had a high initial discharge capacity and a good reversibility.

Sputtered Thin Films for Lithium Ion Microbatteries: Recent Results on TiN Lithium Barrier Diffusion Layer, Au Negative and C-LiFePO4 Positive Electrodes

With the development of energy autonomous systems (sensors, connected objects, active RFID…), the interest for energy storage devices as microbatteries is growing. Such batteries are based on lithium technologies. Classically, a thin film lithium microbattery consists of the deposition on a substrate of several functional layers such as 2 current collectors, a positive and a negative (lithium metal) electrodes separated by a solid electrolyte (fig. 1). Our study focuses on sputtered thin films deposited on a silicon substrate (figure 1).To prevent the lithium diffusion from the active layers to the silicon substrate, a diffusion barrier layer should be integrated in the structure. Titanium Nitride (TiN) is really developed in microelectronics and TiN could be used both as a current collector and as lithium diffusion barrier (1) for the negative electrode (2, 3). The purpose of this study is to understand the influence of deposition parameters on the titanium nitride characteristics in order to get low resistivity and low electrochemically active thin film against lithium ion insertion. To do so, experiments have been led to get resistivity and Li-capacity as function of the deposition parameters. Structural properties such as crystalline texture, roughness and microstructure have been also studied (figure 2).Prior to the thin film deposition of gold materials and their electrochemical characterization, in operando X ray diffraction measurement has been performed on a gold foil in order to clearly understand the structural evolution of the lithium-gold alloys (4). As in the lithium-silicon alloys, the understanding is really complicated and the number of publications is limited (5-7): ours conclusion and results will be presented. Then, a negative gold electrode has been deposited on the TiN current collector by sputtering means. It has been shown that the electrochemical study is quite difficult if the gold thin film is deposited directly on the silicon wafer owing to the lithium-silicon alloys. It has been demonstrated the benefit from the TiN layer by TOF-SIMS measurement where the lithium ion bas been blocked in the gold electrode due to the TiN barrier layer. Galvanostatic cycling tests has been carried out on the gold electrode and two plateaus have been highlighted corresponding to the lithium-poor and lithium-rich gold phases. The reversibility of these two plateaus have been studied in liquid (1M LITFSI/EC/DEC) as well as in solid (sputtered LIPON) electrolytes and will be presented.Finally, the C-LiFePO4 positive electrode has been studied by RF and pulsed DC magnetron sputtering deposition means. The electrochemical (cyclic voltammetry, galvanostatic cycling) experiments on the thin films as a function of the deposition parameters (figure 3) will also be reported. Micro-patterning of the C-LiFePO4 layer has been realized for the first time by deep reactive ion etching. All the building blocks mixing material deposition/characterization and microelectronic fabrication have been developed in this study and paves the ways to the technological fabrication of thin film lithium-ion microbattery based on this technology. Acknowledgments: The authors want to thank the French network of the electrochemical energy storage (RS2E) for this support. This research is financially supported by the ANR and the DGA within the MECANANO project (ANR-12-ASTR-0032-01). The French RENATECH network and the CPER CIA are greatly acknowledged.1. L. Baggetto, R. A. H. Niessen, F. Roozeboom and P. H. L. Notten, Advanced Functional Materials, 18, 1057 (2008).2. S.-K. Rha, W.-J. Lee, D.-I. Kim, S.-Y. Lee, D.-W. Kim, Y.-S. Hwang, S.-S. Chun and C.-O. Park, Thin Solid Films, 320, 134 (1998).3. V. Chakrapani, F. Rusli, M. A. Filler and P. A. Kohl, Journal of Power Sources, 216, 84 (2012).4. A. D. Pelton, Bulletin of Alloy Phase Diagrams 7, 228 (1986).5. G. Taillades, N. Benjelloun, J. Sarradin and M. Ribes, Solid State Ionics 152–153, 119 (2002).6. T. L. Kulova, A. M. Skundin, V. M. Kozhevin, D. A. Yavsin and S. A. Gurevich, Russian Journal of Electrochemistry, 46, 877 (2010).7. A. Gohier, B. Laïk, J.-P. Pereira-Ramos, C. S. Cojocaru and P. Tran-Van, Journal of Power Sources, 203, 135 (2012).

High performance of symmetric micro-supercapacitors based on silicon nanowires using N-methyl-N-propylpyrrolidinium bis(trifluoromethylsulfonyl)imide as electrolyte

This work describes the development and performance of a symmetric micro-supercapacitor made of nanostructured electrodes based on silicon nanowires (SiNWs) deposited using chemical vapor deposition (CVD) on silicon substrates. The performance of the SiNWs micro-supercapacitor employing an aprotic ionic liquid (N-methyl-N-propylpyrrolidinium bis(trifluoromethylsulfonyl)imide) (PYR13TFSI) as an electrolyte was able to deliver a maximal power density of 182mWcm−2 and a specific energy of 190μJcm−2 operating at a wide cell voltage of 4V with a quasi-ideal capacitive behavior. The lifetime of the device exhibited a remarkable electrochemical stability retaining 75% of the initial capacitance after several million galvanostatic charge–discharge cycles at a high current density of 1mAcm−2. Furthermore, a coulombic efficiency of approximately 99% was obtained after galvanostatic cycling test without structural degradation on the morphology of SiNWs.

Electrochemical performance and kinetic behavior of lithium ion in Li 4 Ti 5 O 12 thin film electrodes

Abstract Li4Ti5O12 thin film electrodes are successfully deposited on Pt/Ti/SiO2/Si substrates by pulsed laser deposition (PLD) technique. The microstructure and morphology of Li4Ti5O12 thin films are characterized by XRD and ESEM. The electrochemical properties of Li4Ti5O12 thin film electrodes are evaluated by galvanostatic cycling test. The kinetic behavior of lithium ions in Li4Ti5O12 thin film electrodes is also conducted using cyclic voltammetry (CV), galvanostatic intermittent titration technique (GITT), and electrochemical impedance spectroscopy (EIS). Li4Ti5O12 thin film electrodes show favorable specific capacities and cycle performance. The chemical diffusion coefficients are found to be in a range of 10−15 to 10−12 cm2 s−1 determined by GITT method. The kinetic parameters obtained from impedance spectra as a function of the cell voltage are investigated in details. The decrease of the charge-transfer resistance (Rct) can be explained by the two-phase transition during lithium insertion into Li4Ti5O12.