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⁺.     

Mesoporous and nanowire Co3O4 as negative electrodes for rechargeable lithium batteries

The conversion reactions associated with mesoporous and nanowire Co(3)O(4) when used as negative electrodes in rechargeable lithium batteries have been investigated. Initially, Li is intercalated into Co(3)O(4) up to x approximately 1.5 Li in Li(x)Co(3)O(4). Thereafter, both materials form a nanocomposite of Co particles imbedded in Li(2)O, which on subsequent charge forms CoO. The capacities on cycling increase on initial cycles to values exceeding the theoretical value for Co(3)O(4) + 8 Li(+) + 8e(-) --> 4 Li(2)O + 3 Co, 890 mAhg(-1), and this is interpreted as due to charge storage in a polymer layer that forms on the high surface area of nanowire and mesoporous Co(3)O(4). After 15 cycles, the capacity decreases drastically for the nanowires due to formation of grains that are separated one from another by a thick polymer layer, leading to electrical isolation. In contrast, the mesoporous Co(3)O(4) losses its mesoporosity and forms a morphology similar to bulk Co(3)O(4) (Co particles imbedded in Li(2)O matrix) with which it exhibits a similar capacity on cycling. In contrast to mesoporous lithium intercalation compounds, which show superior capacity at high rates compared to bulk materials, mesoporosity does not seem to improve the capacity of conversion reactions on extended cycling. If, however, mesoporosity could be retained during the conversion reaction, then higher capacities could be obtained in such systems.     

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.     

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.     

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.     

Effect of fullerene coating on silicon thin film anodes for lithium rechargeable batteries

To improve the electrochemical performances of Si thin film anodes for lithium rechargeable batteries, fullerene thin films are prepared by plasma-assisted evaporation methods to be used as coating materials. Analyses via Raman and X-ray photoelectron spectroscopy indicate that amorphous polymeric films originated from fullerene are formed on the surface of the silicon thin film. The electrochemical performance of these fullerene-coated silicon thin film as an anode material for rechargeable lithium batteries has been investigated by cyclic voltammetry, charge/discharge tests, and electrochemical impedance spectroscopy. The fullerene-coated Si thin films demonstrated a high specific capacity of above 3,000 mAh g⁻¹ as well as good capacity retention for 40 cycles. In comparison with bare silicon anodes, the fullerene-coated silicon thin film showed superior and stable cycle performance which can be attributed to the fullerene coating layer which enhances the Li-ion kinetic property at the electrode/electrolyte interface.     

All-solid-state rechargeable lithium batteries using SnX-P2X5 (X = S and O) amorphous negative electrodes

SnS-P₂S₅ and SnO-P₂O₅ amorphous materials were prepared by a mechanical milling technique. The SnO-P₂O₅ milled materials worked as a reversible electrode with higher capacity than SnO crystal in rechargeable lithium cells with conventional liquid electrolytes. All-solid-state cells with a SnX-P₂X₅ (X = S and O) amorphous electrode and the Li₂S-P₂S₅ glass-ceramic electrolyte were charged and discharged at room temperature. The sulfide electrodes exhibited better charge-discharge performance than the oxide electrodes, suggesting that SnS-P₂S₅ electrodes are more compatible with Li₂S-P₂S₅ sulfide solid electrolytes. All-solid state batteries 80SnS·20P₂S₅/LiCoO₂ showed a charge-discharge plateau of about 3.4 V and high reversible capacity of over 400 mAh/g, even after 50 cycles. The SnX (X = S and O)-based amorphous materials are promising negative electrode materials with high capacity for rechargeable lithium batteries using not only liquid electrolytes but solid electrolytes.     

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     

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.     

High rate performance of lithium manganese nitride and oxynitride as negative electrodes in lithium batteries

The performance of Li_7.9MnN_3.2O_1.6 and Li₇MnN₄ as electrode materials in lithium batteries was analyzed. At 1C rate, capacities of 180 and 230 mAh/g, respectively, were obtained after 50 cycles. If the first charge is done at 0.1C, outstanding capacities of 120–135 mAh/g are observed after 100 cycles at 5C. More lithium can be removed during the charge at 0.1C, leading to a large amount of lithium vacancies that enhance mobility and rate capability. It is proposed that incomplete filling of the vacancies occurs upon cycling, so that the mobility remains high. This performance compares well to that of Li₄Ti₅O₁₂.     

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.     

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     

Sn-0.4BPO4 composite as a promising negative electrode for rechargeable lithium batteries

The structural and textural properties of a Sn-0.4BPO₄ composite material synthesized by ex situ dispersion of β-Sn in a BPO₄ matrix were investigated by using several complementary techniques to study the global order (XRD, TGA-DSC, SEM-XEDS) and the local order (FT-IR, ¹¹⁹Sn Mössbauer spectroscopy and X-ray absorption spectroscopy). The results reveal that the composite material consists of three main components: an electrochemically active species “Sn”, an inactive matrix “BPO₄”, and an amorphous Sn(II) borophosphate which acts as a link between the two former and which improves the cohesion of the composite. The electrochemical performances of the composite material were tested in Swagelok-type cells with metallic Li as counter-electrode. It shows a high reversible capacity of about 500 mAh g^?1 at a C/20 rate, and a very good stability under cycling even at very fast rates of C or C/1.3.     

Surface film formation on a graphite electrode in Li‐ion batteries: AFM and XPS study

The formation of a passivation film (solid electrolyte interphase, SEI) at the surface of the negative electrode of full LiCoO₂/graphite lithium‐ion cells using LiPF₆ (1M ) in carbonate solvents as electrolyte was investigated by means of x‐ray photoelectron spectroscopy (XPS) and atomic force microscopy (AFM). The analyses were carried out at different potentials of the first and the fifth cycles, showing the potential‐dependent character of the surface‐film species formation. These species were mainly identified as Li₂CO₃ up to 3.8 V and LiF up to 4.2 V. This study shows the formation of the SEI during charging and its partial dissolution during discharge. Copyright © 2005 John Wiley & Sons, Ltd.     

Bifunctional air electrodes for flexible rechargeable Zn-air batteries

Flexible rechargeable Zn-air batteries are considered as one of the most promising battery systems to drive flexible and wearable electronic devices owing to their high safety,high gravimetric energy density,low self-discharge and low cost.One of the key challenges is to develop air electrodes with high performance and high mechanical flexibility.This minireview discusses the recent progress in the design and fabrication of flexible air electrodes.It focuses on the latest innovations in bifunctional oxygen reduction reaction and oxygen evolution reaction electrocatalysts,mainly including carbon-based materials(e.g.,heteroatom-doped carbon,metal-nitrogen moieties doped carbon),metal oxides(e.g.,spinel oxides,perovskite oxides) and their composites.It aims to provide an insight into the structureproperty relationship of bifunctional catalysts.We also discuss the challenges and future perspectives.     

Application of polyacrylonitrile-based polymer electrolytes in rechargeable lithium batteries

Polyacrylonitrile (PAN)-based polymer electrolytes have obtained considerable attention due to their fascinating characteristics such as appreciable ionic conductivity at ambient temperatures and mechanical stability. This study is based on the system PAN–ethylene carbonate (EC)–propylene carbonate (PC)–lithium trifluoromethanesulfonate (LiCF₃SO₃). The composition 15 mol% PAN–42 mol% EC–36 mol% PC–7 mol% LiCF₃SO₃ has shown a maximum room temperature conductivity of 1.2?×?10^?3 S cm^?1. Also, it was possible to make a thin, transparent film out of that composition. Cells of the form, Li/PAN–EC–PC–LiCF₃SO₃/polypyrrole (PPy)–alkylsulfonate (AS) were investigated using cyclic voltammetry and continuous charge–discharge tests. When cycled at low scan rates, a higher capacity could be obtained and well-defined peaks were present. The appearance of peaks elucidates the fact that redox reactions occur completely. This well proves the reason for higher capacity. The average specific capacity was about 43 Ah kg^?1. Cells exhibited a charge factor close to unity during continuous charging and discharging, indicating the absence of parasitic reactions.     

A highly cross-linked polymeric binder for high-performance silicon negative electrodes in lithium ion batteries

A support bandage for electrodes: A cross-linked polymeric binder inhibits mechanical fracture of silicon negative electrodes during cycling. Nanosized silicon powder with a 3D interconnected network of poly(acrylic acid) and sodium carboxymethylcellulose as binder exhibits high reversible capacity of over 2000?mAh?g(-1) after 100 cycles at 30?°C while maintaining a high capacity and high current density.     

Use of Sn-Si nanocomposite electrodes for Li rechargeable batteries

The relationship between the structural properties of Sn nano-dots embedded in a Si electrode synthesised by co-sputtering and their electrochemical performance during a lithium insertion and extraction process has been investigated.