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Träfflista för sökning "WFRF:(Sadd Matthew 1994) "

Sökning: WFRF:(Sadd Matthew 1994)

  • Resultat 1-9 av 9
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1.
  • Agostini, Marco, 1987, et al. (författare)
  • Designing a Safe Electrolyte Enabling Long‐Life Li/S Batteries
  • 2019
  • Ingår i: ChemSusChem. - 1864-5631 .- 1864-564X. ; 12:18, s. 4176-4184
  • Tidskriftsartikel (refereegranskat)abstract
    • Lithium–sulfur (Li/S) batteries suffer from “shuttle” reactions in which soluble polysulfide species continuously migrate to and from the Li metal anode. As a consequence, the loss of active material and reactions at the surface of Li limit the practical applications of Li/S batteries. LiNO3 has been proposed as an electrolyte additive to reduce the shuttle reactions by aiding the formation of a stable solid electrolyte interphase (SEI) at the Li metal, limiting polysulfide shuttling. However, LiNO3 is continuously consumed during cycling, especially at low current rates. Therefore, the Li/S battery cycle life is limited by the LiNO3 concentration in the electrolyte. In this work, an ionic liquid (IL) [N-methyl-(n-butyl)pyrrolidinium bis(trifluoromethylsulfonyl)imide] was used as an additive to enable longer cycle life of Li/S batteries. By tuning the IL concentration, an enhanced stability of the SEI and lower flammability of the solutions were demonstrated, that is, higher safety of the battery. The Li/S cell built with a high sulfur mass loading (4 mg cm−2) and containing the IL-based electrolyte demonstrated a stable capacity of 600 mAh g−1 for more than double the number of cycles of a cell containing LiNO3 additive.
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2.
  • Agostini, Marco, 1987, et al. (författare)
  • Rational Design of Low Cost and High Energy Lithium Batteries through Tailored Fluorine-free Electrolyte and Nanostructured S/C Composite
  • 2018
  • Ingår i: ChemSusChem. - 1864-5631 .- 1864-564X. ; 11:17, s. 2981-2986
  • Tidskriftsartikel (refereegranskat)abstract
    • We report a new Li–S cell concept based on an optimized F-free catholyte solution and a high loading nanostructured C/S composite cathode. The Li2S8present in the electrolyte ensures both buffering against active material dissolution and Li+conduction. The high S loading is obtained by confining elemental S (≈80 %) in the pores of a highly ordered mesopores carbon (CMK3). With this concept we demonstrate stabilization of a high energy density and excellent cycling performance over 500 cycles. This Li–S cell has a specific capacity that reaches over 1000 mA h g−1, with an overall S loading of 3.6 mg cm−2and low electrolyte volume (i.e., 10 μL cm−2), resulting in a practical energy density of 365 Wh kg−1. The Li–S system proposed thus meets the requirements for large scale energy storage systems and is expected to be environmentally friendly and have lower cost compared with the commercial Li-ion battery thanks to the removal of both Co and F from the overall formulation.
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3.
  • Agostini, Marco, 1987, et al. (författare)
  • Stabilizing the Performance of High-Capacity Sulfur Composite Electrodes by a New Gel Polymer Electrolyte Configuration
  • 2017
  • Ingår i: ChemSusChem. - 1864-5631 .- 1864-564X. ; 10:17, s. 3490-3496
  • Tidskriftsartikel (refereegranskat)abstract
    • Increased pollution and the resulting increase in global warming are drawing attention to boosting the use of renewable energy sources such as solar or wind. However, the production of energy from most renewable sources is intermittent and thus relies on the availability of electrical energy-storage systems with high capacity and at competitive cost. Lithium–sulfur batteries are among the most promising technologies in this respect due to a very high theoretical energy density (1675 mAh g?1) and that the active material, sulfur, is abundant and inexpensive. However, a so far limited practical energy density, life time, and the scaleup of materials and production processes prevent their introduction into commercial applications. In this work, we report on a simple strategy to address these issues by using a new gel polymer electrolyte (GPE) that enables stable performance close to the theoretical capacity of a low cost sulfur–carbon composite with high loading of active material, that is, 70 % sulfur. We show that the GPE prevents sulfur dissolution and reduces migration of polysulfide species to the anode. This functional mechanism of the GPE membranes is revealed by investigating both its morphology and the Li-anode/GPE interface at various states of discharge/charge using Raman spectroscopy.
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4.
  • Cavallo, Carmen, 1986, et al. (författare)
  • Effect of the Niobium Doping Concentration on the Charge Storage Mechanism of Mesoporous Anatase Beads as an Anode for High-Rate Li-Ion Batteries
  • 2021
  • Ingår i: ACS Applied Energy Materials. - : AMER CHEMICAL SOC. - 2574-0962. ; 4:1, s. 215-225
  • Tidskriftsartikel (refereegranskat)abstract
    • A promising strategy to improve the rate performance of Li-ion batteries is to enhance and facilitate the insertion of Li ions into nanostructured oxides like TiO2. In this work, we present a systematic study of pentavalent-doped anatase TiO2 materials for third-generation high-rate Li-ion batteries. Mesoporous niobium-doped anatase beads (Nb-doped TiO2) with different Nb5+ doping (n-type) concentrations (0.1, 1.0, and 10% at.) were synthesized via an improved template approach followed by hydrothermal treatment. The formation of intrinsic n-type defects and oxygen vacancies under RT conditions gives rise to a metallic-type conduction due to a shift of the Fermi energy level. The increase in the metallic character, confirmed by electrochemical impedance spectroscopy, enhances the performance of the anatase bead electrodes in terms of rate capability and provides higher capacities both at low and fast charging rates. The experimental data were supported by density functional theory (DFT) calculations showing how a different n-type doping can be correlated to the same electrochemical effect on the final device. The Nb-doped TiO2 electrode materials exhibit an improved cycling stability at all the doping concentrations by overcoming the capacity fade shown in the case of pure TiO2 beads. The 0.1% Nb-doped TiO2-based electrodes exhibit the highest reversible capacities of 180 mAh g-1 at 1C (330 mA g-1) after 500 cycles and 110 mAh g-1 at 10C (3300 mA g-1) after 1000 cycles. Our experimental and computational results highlight the possibility of using n-type doped TiO2 materials as anodes in high-rate Li-ion batteries.
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5.
  • Celeste, Arcangelo, et al. (författare)
  • Enhancement of Functional Properties of Liquid Electrolytes for Lithium-Ion Batteries by Addition of Pyrrolidinium-Based Ionic Liquids with Long Alkyl-Chains
  • 2020
  • Ingår i: BATTERIES & SUPERCAPS. - 2566-6223. ; 3:10, s. 1059-1068
  • Tidskriftsartikel (refereegranskat)abstract
    • Three ionic liquid belonging to the N-alkyl-N-methylpyrrolidinium bis(trifluoromethanesulfonyl) imides (Pyr(1),nTFSI with n=4,5,8) have been added as co-solvent to two commonly used electrolytes for Li-ion cells: (a) 1 M lithium hexafluorophosphate (LiPF6) in a mixture of ethylene carbonate (EC) and linear like dimethyl carbonate (DMC) in 1 : 1 v/v and (b) 1 M lithium bis-(trifluoromethanesulfonyl)imide (LiTFSI) in EC : DMC 1 : 1 v/v. These electrolyte formulations (classified as P and T series containing LiPF6 or LiTFSI salts, respectively) have been analyzed by comparing ionic conductivities, transport numbers, viscosities, electrochemical stability as well as vibrational properties. In the case of the Pyr(1,5)TFSI and Pyr(1,8)TFSI blended formulations, this is the first ever reported detailed study of their functional properties in Li-ion cells electrolytes. Overall, P-electrolytes demonstrate enhanced properties compared to the T-ones. Among the various P electrolytes those containing Pyr(1,4)TFSI and Pyr(1,5)TFSI limit the accumulation of irreversible capacity upon cycling with satisfactory performance in lithium cells.
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6.
  • Liu, Qiao, et al. (författare)
  • Enhanced ionic conductivity and interface stability of hybrid solid-state polymer electrolyte for rechargeable lithium metal batteries
  • 2019
  • Ingår i: Energy Storage Materials. - 2405-8297. ; 23, s. 105-111
  • Tidskriftsartikel (refereegranskat)abstract
    • Compared to conventional organic liquid electrolyte, solid-state polymer electrolytes are extensively considered as an alternative candidate for next generation high-energy batteries because of their high safety, non-leakage and electrochemical stability with the metallic lithium (Li) anode. However, solid-state polymer electrolytes generally show low ionic conductivity and high interfacial impedance to electrodes. Here we report a hybrid solid-state electrolyte, presenting an ultra-high ionic conductivity of 3.27 mS cm −1 at room temperature, a wide electrochemical stability window of 4.9 V, and non-flammability. This electrolyte consists of a polymer blend matrix (polyethylene oxide and poly (vinylidene fluoride-co-hexafluoropropylene)), Li + conductive ceramic filler (Li 1.5 Al 0.5 Ge 1.5 (PO 4 ) 3 ) and a solvate ionic liquid (LiFSI in tetra ethylene glycol dimethyl ether, 1:1 in molar ratio) as plasticizer. The introduction of the solvate ionic liquid to the solid-state electrolyte not only improves its ionic conductivity but also remarkably enhances the stability of the interface with Li anode. When applied in Li metal batteries, a Li|Li symmetric cell can operate stably over 800 h with a minimal polarization of 25 mV and a full Li|LiFePO 4 cell delivers a high specific capacity of 158 mAh g −1 after 100 cycles at room temperature.
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7.
  • Liu, Yangyang, et al. (författare)
  • Insight into the Critical Role of Exchange Current Density on Electrodeposition Behavior of Lithium Metal
  • 2021
  • Ingår i: Advanced Science. - 2198-3844. ; 8:5
  • Tidskriftsartikel (refereegranskat)abstract
    • Due to an ultrahigh theoretical specific capacity of 3860 mAh g−1, lithium (Li) is regarded as the ultimate anode for high-energy-density batteries. However, the practical application of Li metal anode is hindered by safety concerns and low Coulombic efficiency both of which are resulted fromunavoidable dendrite growth during electrodeposition. This study focuses on a critical parameter for electrodeposition, the exchange current density, which has attracted only little attention in research on Li metal batteries. A phase-field model is presented to show the effect of exchange current density on electrodeposition behavior of Li. The results show that a uniform distribution of cathodic current density, hence uniform electrodeposition, on electrode is obtained with lower exchange current density. Furthermore, it is demonstrated that lower exchange current density contributes to form a larger critical radius of nucleation in the initial electrocrystallization that results in a dense deposition of Li, which is a foundation for improved Coulombic efficiency and dendrite-free morphology. The findings not only pave the way to practical rechargeable Li metal batteries but can also be translated to the design of stable metal anodes, e.g., for sodium (Na), magnesium (Mg), and zinc (Zn) batteries.
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8.
  • Sadd, Matthew, 1994 (författare)
  • In-situ Investigations of Lithium-Sulfur Batteries
  • 2019
  • Licentiatavhandling (övrigt vetenskapligt)abstract
    • As the demand for high energy-density storage devices increases, we must look beyond the current state of the art technology, the lithium-ion battery. Lithium-ion battery technologies are approaching their theoretical limit in terms of capacity, and now that the demand for longer-range electric vehicles (EVs) and the implementation of grid storage is increasing, we need to provide technologies that can go beyond what is currently possible. In order to increase the capacity of batteries, and to develop more sustainable technologies to meet the rising demand, we must turn to new chemistries. A suggested Next-Generation Battery chemistry is based on the electrochemical reaction between lithium and sulfur. This chemistry does not rely on intercalation reactions as the Li-ion battery is, but instead employs conversion chemistry. At discharge elemental sulfur is reduced and converted to polysulfides, yielding a maximum specific capacity of 1672 mAhg-1, up to 6 times the theoretical maximum capacity of state-of-the-art Li-ion battery materials. Thus, the lithium-sulfur technology is a suitable successor due to a potentially higher energy density. In addition, there is also the potential to create sustainable systems made from low-cost and high abundance elements, while also creating less toxic and safer devices than those which are currently available for commercially. In our quest to reach a working lithium-sulfur battery there are a series of challenges that must be addressed, many of which originate from the complex reactions and mechanisms of the lithium-sulfur cell. Soluble Li-polysulfide species are formed during cell operation in commonly used electrolytes, these species are highly mobile and react with the Li-metal anode used. This interaction leads to the unwanted reduction of polysulfide species at the anode, causing the polysulfide shuttle, and capacity fade due to the irreversible deposition of active material on the Li-metal surface. A series of methods have been used to address the unwanted reactions, such as the use of novel additives in the electrolyte to form a stable solid-electrolyte interphase (SEI). In this thesis the unique character of polysulfide species is addressed, and methods discussed will show how control of polysulfide dissolution and speciation can be used to improve cell performance. This improvement is realised by designing new electrolytes that block the passage of polysulfides to the Li-metal anode’s surface, and by using polysulfide species in the electrolyte to enable longer lifetime cells by preventing sulfur dissolution while simultaneously supplementing the energy density of a cell by acting as a Li-salt. However, the mechanism of how the polysulfide species behave is not fully understood. To monitor how polysulfides interact with the Li-metal when they act as charge carriers, operando Raman spectroscopy has been employed to track polysulfide concentration changes in a cell and reveal new insights on the mechanisms of polysulfides as Li-salts.
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9.
  • Sun, Jinhua, 1987, et al. (författare)
  • Real-time imaging of Na+ reversible intercalation in "Janus" graphene stacks for battery applications
  • 2021
  • Ingår i: Science advances. - 2375-2548. ; 7:22
  • Tidskriftsartikel (refereegranskat)abstract
    • Sodium, in contrast to other metals, cannot intercalate in graphite, hindering the use of this cheap, abundant element in rechargeable batteries. Here, we report a nanometric graphite-like anode for Na+ storage, formed by stacked graphene sheets functionalized only on one side, termed Janus graphene. The asymmetric functionalization allows reversible intercalation of Na+, as monitored by operando Raman spectroelectrochemistry and visualized by imaging ellipsometry. Our Janus graphene has uniform pore size, controllable functionalization density, and few edges; it can store Na+ differently from graphite and stacked graphene. Density functional theory calculations demonstrate that Na+ preferably rests close to -NH2 group forming synergic ionic bonds to graphene, making the interaction process energetically favorable. The estimated sodium storage up to C6.9Na is comparable to graphite for standard lithium ion batteries. Given such encouraging Na+ reversible intercalation behavior, our approach provides a way to design carbon-based materials for sodium ion batteries.
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  • Resultat 1-9 av 9

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