Fe/Si multi-layer thin film anodes for lithium rechargeable thin film batteries

Fe/Si multi-layer thin films were prepared by alternate deposition using an electron-beam evaporation method. Electrochemical results through galvanostatic charge–discharge experiments are presented. It appears that the volumetric expansion of silicon during cycling can be effectively suppressed by forming a Fe layer between Si layers. The electrochemical characteristics of Fe/Si multi-layer film electrode can be controlled by the thickness, and number of stacked Si layers, and post-annealing.     

Zinc tetrathiomolybdate as novel anodes for rechargeable lithium batteries

An ever first attempt has been made to investigate the anode performance characteristics of zinc tetrathiomolybdate. The poor crystallined zinc tetrathiomolybdate was prepared by precipitation method from Na₂MoO₄, ZnSO₄·7H₂O, and CH₃CSNH₂ as starting materials. Galvanostatic data in the voltage range of 0.01–2.0 V up to 20 cycles at a rate of 100 mA g⁻¹ revealed that the material gave high reversible capacities and good performance.     

Alkaline composite film as a separator for rechargeable lithium batteries

We report a new type of separator film for application in rechargeable lithium and lithium-ion batteries. The films are made of mainly alkaline calcium carbonate (CaCO₃) and a small amount of polymer binder. Owing to porosity and capillarity, the composite films show excellent wettability with non-aqueous liquid electrolytes. Typically, the composite films composed of CaCO₃ and Teflon and wetted with 1 M LiPF₆ dissolved in a solvent mixture of ethylene carbonate (EC) and ethyl methyl carbonate (EMC) (30:70 wt%) exhibit an ionic conductivity as high as 2.5–4 mS/cm at 20 °C, in a comparable range with that (3.4 mS/cm) of the commercial Celgard membrane. In the batteries, the composite film not only serves as a physical separator but also neutralizes acidic products, such as HF formed by LiPF₆ hydrolysis, as well as those formed by solvent oxidative decomposition. A Li/LiMn₂O₄ test cell was employed to examine the electrochemical compatibility of the composite film. We observed that the composite film cell showed an improved cycling performance since the alkaline CaCO₃ neutralizes the acidic products, which otherwise promote dissolution of the electrode active materials. More importantly, the composite film cell displayed a superior performance on high-rate cycling, which was probably the result of the less resistive interface formed between the electrode and the composite film.     

Nanomaterials for rechargeable lithium batteries

Energy storage is more important today than at any time in human history. Future generations of rechargeable lithium batteries are required to power portable electronic devices (cellphones, laptop computers etc.), store electricity from renewable sources, and as a vital component in new hybrid electric vehicles. To achieve the increase in energy and power density essential to meet the future challenges of energy storage, new materials chemistry, and especially new nanomaterials chemistry, is essential. We must find ways of synthesizing new nanomaterials with new properties or combinations of properties, for use as electrodes and electrolytes in lithium batteries. Herein we review some of the recent scientific advances in nanomaterials, and especially in nanostructured materials, for rechargeable lithium-ion batteries.     

Surface film formation on graphite negative electrodes in rechargeable lithium batteries

The choice of solvent is quite important to obtain good protecting surface film on graphite negative electrodes in rechargeable lithium batteries. A subtle difference of the molecular structure of solvent greatly affects the easiness of surface film formation. In order to understand the solvent effects and to elucidate the mechanism of surface film formation, morphology changes of the basal plane of highly oriented pyrolytic graphite were studied using electrochemical scanning tunneling microscopy (EC‐STM). In this article, our recent results of EC‐STM observation in different solvent systems are reviewed.     

Nanocrystalline NiMoO4 with an ordered mesoporous morphology as potential material for rechargeable thin film lithium batteries

Nanocrystalline nickel molybdate (NiMoO(4)) thin film electrodes with a 3D honeycomb structure of uniform 17 nm diameter pores were successfully produced through facile polymer templating strategies. These novel sol-gel type materials exhibit enhanced lithium ion storage capabilities, and thus show promise for battery applications.     

Intercalation materials for lithium rechargeable batteries

An overview is given of intercalation materials for both the negative and the positive electrodes of lithium batteries, including the results of our own research. As well as lithium metal as a negative electrode, we consider insertion materials based on aluminium alloys. In the case of the positive electrode metal-oxides based on manganese, nickel and cobalt are discussed. Received: 27 May 1997 / Accepted: 30 July 1997     

Electrochemical performance of silicon thin film anodes covered by diamond-like carbon with various surface coating morphologies

Four different kinds of diamond-like carbon (DLC) coating morphologies on the surface of silicon films were prepared directly on a copper foil by using radio frequency plasma-enhanced chemical vapor deposition at 200 °C. A thin double layer film consisting of DLC (60 nm) and silicon film (250 nm) was fabricated for use as the anode material of lithium secondary batteries, and its electrochemical performance was also examined with special attention being paid to the surface coverage of the DLC film. The full coverage of silicon by the DLC film resulted in poor capacity due to the ensuing low reactivity with the lithium ions. On the other hand, the partial coating of the DLC film on the silicon film not only reduced the capacity fading, but also increased the discharge capacity during the charge/discharge cycles. These results indicated that the good dispersion of the DLC coating, obtained by using a smaller coating sector on the silicon film, improved the integrity of the electrode structure, thus giving higher capacities and reduced capacity fading.     

Metal-catalyzed organosulfur cathodes for rechargeable lithium batteries

Extensive studies were carried out to apply composite materials composed of polyaniline (PAn) and 2,5-dimercapto-1,3,4-thiadiazole (DMcT) to develop cathode materials which exhibit high energy densities. Previous results have established that composites of PAn and DMcT which are coated onto copper substrates exhibit greatly enhanced charge and discharge performance. It is shown that composite materials composed of DMcT, PAn, and Cu ion have the ability to be reversibly charged and discharged at ca. 260 A h per kg-cathode (ca. 830 W h per kg-cathode) for more than 80 cycles. These two results are explored in general in this contribution via investigation of the electron transfer reactions between the components using UV/Vis and investigation of the copper substrate/DMcT chemistry using electrochemical quartz crystal microbalance and phase modulated interferometric microscopy.     

High safety separators for rechargeable lithium batteries

Lithium-ion batteries(LIBs) are presently dominant mobile power sources due to their high energy density, long lifespan, and low self-discharging rates. The safety of LIBs has been concerned all the time and become the main problem restricting the development of high energy density LIBs. As a significant part of LIBs, the properties of separators have a significant effect on the capacity and performances of batteries and play an important role in the safety of LIBs. In recent years, researchers devoted themselves to the development of various multi-functional safe separators from different views of methods, materials, and practical requirements. In this review, we mainly focus on the recent progress in the development of high-safety separators with high thermal stability, good lithium dendritic resistance, high mechanical strength and novel multifunction for high-safety LIBs and have in-depth discussions regarding the separator's significant contribution to enhance the safety and performances of the batteries. Furthermore, the future directions and challenges of separators for the next-generation high-safety and high energy density rechargeable lithium batteries are also provided.     

Thin film nonstoichiometric chromium oxide-based cathode material for rechargeable and primary lithium batteries

The application of nonstoichiometric chromium oxide-based thin film cathodes in lithium rechargeable and primary batteries operating at high rates has been demonstrated. Films of varying composition have been obtained by anionic Cr (VI) species electrodeposition on a 1X18N10Т grade stainless steel cathode from fluoride-containing electrolytes. The effect of film doping by Li⁺ ions during its electrosynthesis has been сonsidered. As-prepared films were studied by scanning and transmission electron microscopies, 3D optical profiler, thermogravimetric analysis, chemical analysis, and X-ray diffraction (XRD). The main phase components of the electrodeposited films regardless of Li⁺ in an electrolyte are Cr₂O₃, α-CrOOH, β-CrOOH, and metallic chromium as shown by XRD pattern refinement. The electrochemical reduction rate in a non-aqueous electrolyte (1 M LiClO₄ in PC/DME) correlates with the chromium oxide-hydroxide component content of film. Primary CrO _x -Li CR2325 mock-up cathode coating can be discharged in a pulsed mode at 10 Ω external resistance with 80–84 mA cm^?2 current densities for 10–100 ms. Thin film cathodes electrodeposited in the presence of lithium ions become rechargeable when the lithium content of the film reaches 0.02 wt.%. Mock-ups of CR2325 coin battery with a thin film cathode doped with lithium ions can be discharged more than 40 times with 136 mAh g^?1 specific capacity, 461 Wh kg^?1 specific energy and 154 W kg^?1 power density at 30 kΩ external resistance. The simplicity of thin film preparation makes this technology promising for thin film lithium batteries.     

Electrode materials for aqueous rechargeable lithium batteries

In this review, we describe briefly the historical development of aqueous rechargeable lithium batteries, the advantages and challenges associated with the use of aqueous electrolytes in lithium rechargeable battery with an emphasis on the electrochemical performance of various electrode materials. The following materials have been studied as cathode materials: LiMn₂O₄, MnO₂, LiNiO₂, LiCoO₂, LiMnPO₄, LiFePO₄, and anatase TiO₂. Addition of certain additives like TiS₂, TiB₂, CeO₂, etc. is found to increase the performance of MnO₂ cathode. The following materials have been studied as anode materials: VO₂ (B), LiV₃O₈, LiV₂O₅, LiTi₂(PO4)₃, TiP₂O₃, and very recently conducting polymer, polypyrrole (PPy). The cell PPy/LiCoO₂, constructed using polypyrrole as anode delivers an average voltage of 0.86?V with a discharge capacity of 47.7?mA?h?g^?1. It retains the capacity for first 120 cycles. The cell, LiTi₂(PO₄)₃/1?M Li₂SO₄/LiMn₂O₄, delivers a capacity of 40?mA?h?g^?1 and specific energy of 60?mW?h?g^?1 with an output voltage of 1.5?V over 200 charge?Cdischarge cycles. An aqueous lithium cell constructed using MWCNTs/LiMn₂O₄ as cathode material is found to exhibit more than 1,000 cycles with good rate capability.     

Block copolymer electrolytes for rechargeable lithium batteries

Ion‐conducting block copolymers (BCPs) have attracted significant interest as conducting materials in solid‐state lithium batteries. BCP self‐assembly offers promise for designing ordered materials with nanoscale domains. Such nanostructures provide a facile method for introducing sufficient mechanical stability into polymer electrolyte membranes, while maintaining the ionic conductivity at levels similar to corresponding solvent‐free homopolymer electrolytes. This ability to simultaneously control conductivity and mechanical integrity provides opportunities for the fabrication of sturdy, yet easily processable, solid‐state lithium batteries. In this review, we first introduce several fundamental studies of ion conduction in homopolymers for the understanding of ion transport in the conducting domain of BCP systems. Then, we summarize recent experimental studies of BCP electrolytes with respect to the effects of salt‐doping and morphology on ionic conductivity. Finally, we present some remaining challenges for BCP electrolytes and highlight several important areas for future research. © 2013 Wiley Periodicals, Inc. J. Polym. Sci., Part B: Polym. Phys. 2014 , 52, 1–16     

Enhancement of thin film tin oxide negative electrodes for lithium batteries

Thin films of pure SnO₂, of the Sn/Li₂O layered structure, and of Sn/Li₂O were fabricated by sputtering method, while a `lithium-reacted tin oxide thin film' was assembled by the evaporation of lithium metal onto a SnO₂ thin film. Film structure and charge/discharge characteristics were compared. The lithium-reacted tin oxide thin film, the Sn/Li₂O layered structure, and the Sn/Li₂O co-sputtered thin films did not show any irreversible side reactions of forming Li₂O and metallic Sn near 0.8 V vs Li/Li⁺. The initial charge retention of the Sn/Li₂O layered structure and Sn/Li₂O co-sputtered thin films was about 50% and a similar value was found for the lithium-reacted tin oxide thin film (more than 60%). Sn/Li₂O layered structure and Sn/Li₂O co-sputtered thin films showed better cycling behavior over 500 cycles than the pure SnO₂ and lithium-reacted tin oxide thin film in the cut-off range from 1.2 to 0 V vs Li/Li⁺.     

Carbon nanotube reinforced NiO fibers for rechargeable lithium batteries

Single-wall carbon nanotubes (SWNTs) reinforced NiO fibers with diameter smaller than 50 nm have successfully been prepared by electrospinning method combined with calcination. The SWNTs homogeneously distributed in the NiO fibers were characterized by high resolved transmission electron microscopy, selected area electron diffraction, and Raman spectroscopy. Charge and discharge data showed that 3D network structures of NiO–SWNTs fibers exhibited a relatively higher reversible capacity and lower capacity loss than that of NiO at the charge and discharge current density of 2C, and its discharge capacity was about 337 mAh/g after 20 cycles. Our results demonstrated that the SWNTs reinforced fibers had a better cycling performance at large charge and discharge current densities.     

Sandwich-type functionalized graphene sheet-sulfur nanocomposite for rechargeable lithium batteries

A functionalized graphene sheet-sulfur (FGSS) nanocomposite was synthesized as the cathode material for lithium-sulfur batteries. The structure has a layer of functionalized graphene sheets/stacks (FGS) and a layer of sulfur nanoparticles creating a three-dimensional sandwich-type architecture. This unique FGSS nanoscale layered composite has a high loading (70 wt%) of active material (S), a high tap density of ～0.92 g cm(-3), and a reversible capacity of ～505 mAh g(-1) (～464 mAh cm(-3)) at a current density of 1680 mA g(-1) (1C). When coated with a thin layer of cation exchange Nafion film, the migration of dissolved polysulfide anions from the FGSS nanocomposite was effectively reduced, leading to a good cycling stability of 75% capacity retention over 100 cycles. This sandwich-structured composite conceptually provides a new strategy for designing electrodes in energy storage applications.     

Nanocrystalline MnO thin film anode for lithium ion batteries with low overpotential

Nanocrystalline MnO thin film has been prepared by a pulsed laser deposition (PLD) method. The reversible lithium storage capacity of the MnO thin film electrodes at 0.125C is over 472 mAh g^?1 (3484 mAh cm^?3) and can be retained more than 90% after 25 cycles. At a rate of 6C, 55% value of the capacity at 0.125C rate can be obtained for both charge and discharge. As-prepared MnO thin film electrodes show the lowest values of overpotential for both charge and discharge among transition metal oxides. All these performances make MnO a promising high capacity anode material for Li-ion batteries.     

High capacity SnxSbyCuz composite anodes for lithium ion batteries

To increase the volumetric discharge capacity of negative electrode for rechargeable lithium batteries, a composite anode Sn_xSb_yCu_z has been synthesized by using high energy mechanical ball milling method. The synthesized composite anode materials have been characterized by X-ray diffraction and SEM analysis. The charge/discharge characteristics of the fabricated coin cells have been evaluated galvanostatically in the potential range 0.01–2 V using 1 M LiPF₆ in 1:1 EC/DEC as electrolyte. Results indicate that the composition with 90 wt% Sn, 8 wt% Sb and 2 wt% Cu delivers an average discharge capacity of 740 mAh g⁻¹ over the investigated 50 cycles which is a potential candidate for use as an anode material for lithium rechargeable cells.     

Development of sulfide glass-ceramic electrolytes for all-solid-state lithium rechargeable batteries

Development of Li₂S–P₂S₅-based glass-ceramic electrolytes is reviewed. Superionic crystals of Li₇P₃S₁₁ and Li_3.25P_0.95S₄ were precipitated from the Li₂S–P₂S₅ glasses at the selected compositions. These high temperature or metastable phases enhanced conductivity of glass ceramics up to over 10⁻³ S cm⁻¹ at room temperature. The original (or mother) glass electrolytes itself showed somewhat lower conductivity of 10⁻⁴ S cm⁻¹ and have important role as a precursor for obtaining the superionic crystals, which were not synthesized by a conventional solid-state reaction. The substitution of P₂O₅ for P₂S₅ at the composition 70Li₂S·30P₂S₅ (mol%) improved both conductivity and electrochemical stability of glass-ceramic electrolytes. The all-solid-state In/LiCoO₂ cell using the 70Li₂S·27P₂S₅·3P₂O₅ (mol%) glass-ceramic electrolyte showed initial capacity of 105 mAh g⁻¹ (gram of LiCoO₂) at the current density of 0.13 mA cm⁻² and exhibited higher electrochemical performance than that using the 70Li₂S·30P₂S₅ glass-ceramic electrolyte.