273 research outputs found

    High performance Na0.5[Ni0.23Fe0.13Mn0.63]O2 cathode for sodium-ion battery

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    The synthesis of a new layered cathode material, Na0.5[Ni0.23Fe0.13Mn0.63]O2, and its characterization in terms of crystalline structure and electrochemical performance in a sodium cell, is reported. X-ray diffraction studies and high resolution SEM images reveal a well-defined P2-type layered structure, while the electrochemical tests evidence excellent characteristics in terms of high capacity, extending up to 200 mAh g-1, and cycle life, up to 70 cycles. This performance, in addition to the low cost and environmental compatibility of its component, poses Na0.5[Ni0.23Fe0.13Mn0.63]O2 among the best promising materials for the next generation of sodium ion batteries

    Exceptional long-life performance of lithium-ion batteries using ionic liquid-based electrolytes

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    Dieser Beitrag ist mit Zustimmung des Rechteinhabers aufgrund einer (DFG geförderten) Allianz- bzw. Nationallizenz frei zugÀnglich.This publication is with permission of the rights owner freely accessible due to an Alliance licence and a national licence (funded by the DFG, German Research Foundation) respectively.Advanced ionic liquid-based electrolytes are herein characterized for application in high performance lithium-ion batteries. The electrolytes based on either N-butyl-N-methylpyrrolidinium bis(trifluoromethanesulfonyl) imide (Pyr(14)TFSI), N-butyl-N-methylpyrrolidinium bis(fluoro-sulfonyl) imide (Pyr(14)FSI), N-methoxy-ethyl-N-methylpyrrolidinium bis(trifluoromethane-sulfonyl) imide (Pyr(12O1)TFSI) or N-N-diethyl-N-methyl-N-(2methoxyethyl) ammonium bis(trifluoromethanesulfonyl) imide (DEMETFSI) ionic liquids and lithium bis(trifluoromethanesulfonyl) imide (LiTFSI) salt are fully characterized in terms of ionic conductivity, viscosity, electrochemical properties and lithium-interphase stability. All IL-based electrolytes reveal suitable characteristics for application in batteries. Lithium half-cells, employing a LiFePO4 polyanionic cathode, show remarkable performance. In particular, relevant efficiency and rate-capability are observed for the Py14FSI-LiTFSI electrolyte, which is further characterized for application in a lithium-ion battery composed of the alloying Sn-C nanocomposite anode and LiFePO4 cathode. The IL-based full-cell delivers a maximum reversible capacity of about 160 mA h g(-1) (versus cathode weight) at a working voltage of about 3 V, corresponding to an estimated practical energy of about 160 W h kg(-1). The cell evidences outstanding electrochemical cycle life, i.e., extended over 2000 cycles without signs of decay, and satisfactory rate capability. This performance together with the high safety provided by the IL-electrolyte, olivine-structure cathode and Li-alloying anode, makes this cell chemistry well suited for application in new-generation electric and electronic devices

    Reciprocal irreversibility compensation of LiNi0.2Co0.2Al0.1Mn0.45O2 cathode and silicon oxide anode in new Li-ion battery

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    A layered LiNi0.2Co0.2Al0.1Mn0.45O2 cathode is herein synthetized and investigated. Scanning electron micro- scopy (SEM) shows the layered morphology of the composite powder, while energy dispersive X-ray spectroscopy (EDS) and Inductively Coupled Plasma-Mass Spectrometry (ICP-MS) confirm the achieved stoichiometry. X-ray diffraction (XRD) well identifies the layered structure unit cell, and Raman spectroscopy displays the corre- sponding M-O bonds motions. The cycling voltammetry (CV) of LiNi0.2Co0.2Al0.1Mn0.45O2 in lithium half-cell reveals an electrochemical process characterized by a remarkable irreversible oxidation taking place at 4.6 V vs. Li+/Li during the first scan, and subsequent reversible Li (de)intercalation centered at 3.8 V vs. Li+/Li with interphase resistance limited to 16 Ω upon activation as indicated by electrochemical impedance spectroscopy (EIS). The relevant irreversibility during first charge is also detected by galvanostatic cycling in a lithium half-cell subsequently operating at an average voltage of 3.8 V with a stable trend, and a maximum specific capacity of 130 mAh g− 1. The initial irreversible capacity of the layered cathode is advantageously exploited for compen- sating the pristine inefficiency of the Li-alloying composite anode in a proof-of-concept Li-ion battery achieved by combining the LiNi0.2Co0.2Al0.1Mn0.45O2 with a silicon oxide composite (SiOx-C) without any preliminary pre- treatment of the electrodes. The full-cell displays a cycling behavior strongly influenced by the anode/cathode ratio, and the corresponding EIS performed both on the single electrodes and on the Li-ion cell by using an additional lithium reference suggests a controlling role of the anode interphase and possible enhancements through a slight excess of cathode material

    A lithium-ion battery based on a graphene nanoflakes ink anode and a lithium iron phosphate cathode

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    Li-ion rechargeable batteries have enabled the wireless revolution transforming global communication. Future challenges, however, demands distributed energy supply at a level that is not feasible with the current energy-storage technology. New materials, capable of providing higher energy density are needed. Here we report a new class of lithium-ion batteries based on a graphene ink anode and a lithium iron phosphate cathode. By carefully balancing the cell composition and suppressing the initial irreversible capacity of the anode, we demonstrate an optimal battery performance in terms of specific capacity, i.e. 165 mAhg-1, estimated energy density of about 190 Whkg-1 and life, with a stable operation for over 80 charge-discharge cycles. We link these unique properties to the graphene nanoflake anode displaying crystalline order and high uptake of lithium at the edges, as well as to its structural and morphological optimization in relation to the overall battery composition. Our approach, compatible with any printing technologies, is cheap and scalable and opens up new opportunities for the development of high-capacity Li-ion batteries.Comment: 17 pages, 10 figure

    Nanostructured tin-carbon/ LiNi0.5Mn1.5O4 lithium-ion battery operating at low temperature

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    An advanced lithium ion battery using nanostructured tinecarbon lithium alloying anode and a high voltage LiNi0.5Mn1.5O4 spinel-type cathode is studied, with particular focus to the low temperature range. The stable behavior of the battery is assured by the use of an electrolyte media based on a LiPF6 salt dissolved in EC-DEC-DMC, i.e. a mixture particularly suitable for the low temperature application. Cycling tests, both in half cells and in full lithium ion battery using the SneC anode and the LiNi0.5Mn1.5O4 cathode, performed in a temperature range extending from room temperature to "30 C, indicate that the electrode/electrolyte configuration here adopted may be suitable for effective application in the lithium ion battery field. The full cell, cycled at -5 °C, shows stable capacity of about 105 mAh g-1 over more than 200 chargee-discharge cycles that is considered a relevant performance considering the low temperature region

    Physical activation of graphene: An effective, simple and clean procedure for obtaining microporous graphene for high-performance Li/S batteries

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    Graphene nanosheets are a promising scaffold to accommodate S for achieving high performanceLi/S battery. Nanosheet activation is used as a viable strategy to induce a micropore system and further improve the battery performance. Accordingly, chemical activation methods dominate despite the need of multiple stages, which slow down the process in addition to making them tiresome. Here, a three-dimensional (3D)N-doped graphene specimen was physically activated with CO2, a clean and single step process, and used for the preparation of a sulfur composite (A-3DNG/S). The A-3DNG/S composite exhibited outstanding electrochemical properties such as an excellent rate capability (1,000 mAh·g─1at 2C), high reversible capacity and cycling stability (average capacity ~ 800 mAh·g─1at 1C after 200cycles), values which exceed those measured in chemically activated graphene. Therefore, these results support the use of physical activation as a simple and efficient alternative to improve the performance of carbons as an S host for high-performance Li-S batteries

    Lithium–Oxygen Battery Exploiting Highly Concentrated Glyme-Based Electrolytes

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    Concentrated solutions of lithium bis(trifluoromethanesulfonyl)imide (LiTFSI) and lithium nitrate (LiNO3) salts in either diethylene-glycol dimethyl-ether (DEGDME) or triethylene-glycol dimethyl-ether (TREGDME) are herein characterized in terms of chemical and electrochemical properties in view of possible applications as the electrolyte in lithium–oxygen batteries. X-ray photoelectron spectroscopy at the lithium metal surface upon prolonged storage in lithium cells reveals the complex composition and nature of the solid electrolyte interphase (SEI) formed through the reduction of the solutions, while thermogravimetric analysis shows a stability depending on the glyme chain length. The applicability of the solutions in the lithium metal cell is investigated by means of electrochemical impedance spectroscopy (EIS), chronoamperometry, galvanostatic cycling, and voltammetry, which reveal high conductivity and lithium transference number as well as a wide electrochemical stability window of both electrolytes. However, a challenging issue ascribed to the more pronounced evaporation of the electrolyte based on DEGDME with respect to TREGDME actually limits the application of the former in the Li/O2 battery. Hence, EIS measurements reveal a very fast increase in the impedance of cells using the DEGDME-based electrolyte upon prolonged exposure to the oxygen atmosphere, which leads to a performance decay of the corresponding Li/O2 battery. Instead, cells using the TREGDME-based electrolyte reveal remarkable interphase stability and much more enhanced response with specific capacity ranging from 500 to 1000 mA h g–1 referred to the carbon mass in the positive electrode, with an associated maximum practical energy density of 450 W h kg–1. These results suggest the glyme volatility as a determining factor for allowing the use of the electrolyte media in a Li/O2 cell. Therefore, electrolytes using a glyme with sufficiently high boiling point, such as TREGDME, which is further increased by the relevant presence of salts including a lithium protecting sacrificial one (LiNO3), can allow the application of the solutions in a safe and high-performance lithium–oxygen battery

    A Stable High-Capacity Lithium-Ion Battery Using a Biomass-Derived Sulfur-Carbon Cathode and Lithiated Silicon Anode

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    A full lithium-ion-sulfur cell with a remarkable cycle life was achieved by combining an environmentally sustainable biomass-derived sulfur-carbon cathode and a pre-lithiated silicon oxide anode. X-ray diffraction, Raman spectroscopy, energy dispersive spectroscopy, and thermogravimetry of the cathode evidenced the disordered nature of the carbon matrix in which sulfur was uniformly distributed with a weight content as high as 75 %, while scanning and transmission electron microscopy revealed the micrometric morphology of the composite. The sulfur-carbon electrode in the lithium half-cell exhibited a maximum capacity higher than 1200 mAh gS−1, reversible electrochemical process, limited electrode/electrolyte interphase resistance, and a rate capability up to C/2. The material showed a capacity decay of about 40 % with respect to the steady-state value over 100 cycles, likely due to the reaction with the lithium metal of dissolved polysulfides or impurities including P detected in the carbon precursor. Therefore, the replacement of the lithium metal with a less challenging anode was suggested, and the sulfur-carbon composite was subsequently investigated in the full lithium-ion-sulfur battery employing a Li-alloying silicon oxide anode. The full-cell revealed an initial capacity as high as 1200 mAh gS−1, a retention increased to more than 79 % for 100 galvanostatic cycles, and 56 % over 500 cycles. The data reported herein well indicated the reliability of energy storage devices with extended cycle life employing high-energy, green, and safe electrode materials