| 1. |
- Agostini, Marco, 1987, et al.
(författare)
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A high-power and fast charging Li-ion battery with outstanding cycle-life
- 2017
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Ingår i: Scientific Reports. - : Springer Science and Business Media LLC. - 2045-2322 .- 2045-2322. ; 7:1
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Tidskriftsartikel (refereegranskat)abstract
- Electrochemical energy storage devices based on Li-ion cells currently power almost all electronic devices and power tools. The development of new Li-ion cell configurations by incorporating innovative functional components (electrode materials and electrolyte formulations) will allow to bring this technology beyond mobile electronics and to boost performance largely beyond the state-of-theart. Here we demonstrate a new full Li-ion cell constituted by a high-potential cathode material, i.e. LiNi0.5Mn1.5O4, a safe nanostructured anode material, i.e. TiO2, and a composite electrolyte made by a mixture of an ionic liquid suitable for high potential applications, i.e. Pyr(1),4PF6, a lithium salt, i.e. LiPF6, and standard organic carbonates. The final cell configuration is able to reversibly cycle lithium for thousands of cycles at 1000 mAg(-1) and a capacity retention of 65% at cycle 2000.
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| 2. |
- Agostini, Marco, 1987, et al.
(författare)
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A mixed mechanochemical-ceramic solid-state synthesis as simple and cost effective route to high-performance LiNi0.5Mn1.5O4 spinels
- 2017
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Ingår i: Electrochimica Acta. - : Elsevier BV. - 0013-4686. ; 235, s. 262-269
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Tidskriftsartikel (refereegranskat)abstract
- The implementation of high potential materials as positive electrodes in high energy Li-ion batteries requires to develop scalable and smart synthetic routes. In the case of the LiNi0.5Mn1.5O4 (LNMO) spinel material, a successful preparation strategy must drive the phase formation in order to obtain structural, morphological and surface properties capable to boost performances in lithium cells and minimize the electrolyte degradation. Here we discuss a novel simple and easily scalable mechanochemical synthetic route, followed by a high temperature annealing in air, to prepare LMNO materials starting from oxides. A synergic doping with chromium and iron has been incorporated, resulting in the spontaneous segregation of a CrOx-rich surface layer. The effect of the annealing temperature on the physico-chemical properties of the LMNO material has been investigated as well as the effect on the performances in Licells.
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| 3. |
- Agostini, Marco, 1987, et al.
(författare)
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Designing a Safe Electrolyte Enabling Long‐Life Li/S Batteries
- 2019
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Ingår i: ChemSusChem. - : Wiley. - 1864-5631 .- 1864-564X. ; 12:18, s. 4176-4184
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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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| 4. |
- Agostini, Marco, 1987, et al.
(författare)
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Designing Highly Conductive Functional Groups Improving Guest-Host Interactions in Li/S Batteries
- 2020
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Ingår i: Small. - : Wiley. - 1613-6810 .- 1613-6829. ; 16:2
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Tidskriftsartikel (refereegranskat)abstract
- Li-sulfur batteries are of great interest due to their potential to surpass the energy densities of other battery types, but the low electronic conductivity of both sulfur and its discharge products requires the use of a conductive host material. The most common is the use of different porous carbons which normally are hydrophobic and hardly retain the polar discharge products of the Li/S reaction, such as Li2S and lithium polysulfides (LiPs), at the working electrode. Functionalized hosts have been proposed as a strategy to improve LiPs interactions, including the use of heteroatom doping, organic frameworks, metals, metal oxides, sulfide particles, and conductive polymers. Despite demonstrating an improved cycle life, the functionalized structures often have an intrinsic limitation related to a low electronic conductivity resulting in slow kinetics and poor rate capability of Li/S cells. Herein, recent research trends aimed at designing sulfur electrodes with highly conductive functional groups on nanostructured hosts surface are reviewed. The main concepts, key developments, and parameters for building 3D hosts architectures that enable fast charge rates and long cycle life at high sulfur loadings are discussed.
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| 5. |
- Agostini, Marco, 1987, et al.
(författare)
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Free-Standing 3D-Sponged Nanofiber Electrodes for Ultrahigh-Rate Energy-Storage Devices
- 2018
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Ingår i: ACS Applied Materials & Interfaces. - : American Chemical Society (ACS). - 1944-8252 .- 1944-8244. ; 10:40, s. 34140-34146
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Tidskriftsartikel (refereegranskat)abstract
- We have designed a self-standing anode built-up from highly conductive 3D-sponged nanofibers, that is, with no current collectors, binders, or additional conductive agents. The small diameter of the fibers combined with an internal spongelike porosity results in short distances for lithium-ion diffusion and 3D pathways that facilitate the electronic conduction. Moreover, functional groups at the fiber surfaces lead to the formation of a stable solid-electrolyte interphase. We demonstrate that this anode enables the operation of Li-cells at specific currents as high as 20 A g-1 (approx. 50C) with excellent cycling stability and an energy density which is >50% higher than what is obtained with a commercial graphite anode.
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| 6. |
- Agostini, Marco, 1987, et al.
(författare)
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Minimizing the Electrolyte Volume in Li–S Batteries: A Step Forward to High Gravimetric Energy Density
- 2018
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Ingår i: Advanced Energy Materials. - : Wiley. - 1614-6840 .- 1614-6832. ; 8:26
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Tidskriftsartikel (refereegranskat)abstract
- Sulfur electrodes confined in an inert carbon matrix show practical limitations and concerns related to low cathode density. As a result, these electrodes require a large amount of electrolyte, normally three times more than the volume used in commercial Li-ion batteries. Herein, a high-energy and high-performance lithium–sulfur battery concept, designed to achieve high practical capacity with minimum volume of electrolyte is proposed. It is based on deposition of polysulfide species on a self-standing and highly conductive carbon nanofiber network, thus eliminating the need for a binder and current collector, resulting in high active material loading. The fiber network has a functionalized surface with the presence of polar oxygen groups, with the aim to prevent polysulfide migration to the lithium anode during the electrochemical process, by the formation of S–O species. Owing to the high sulfur loading (6 mg cm−2) and a reduced free volume of the sulfide/fiber electrode, the Li–S cell is designed to work with as little as 10 µL cm−2of electrolyte. With this design the cell has a high energy density of 450 Wh kg−1, a lifetime of more than 400 cycles, and the possibility of low cost, by use of abundant and eco-friendly materials.
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| 7. |
- Agostini, M., et al.
(författare)
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Polysulfide-containing Glyme-based Electrolytes for Lithium Sulfur Battery
- 2015
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Ingår i: Chemistry of Materials. - : American Chemical Society (ACS). - 1520-5002 .- 0897-4756. ; 27:13, s. 4604-4611
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Tidskriftsartikel (refereegranskat)abstract
- A new comparative investigation of lithium sulfur cells employing a tetraethylene glycol dimethyl ether-lithium trifluoromethanesulfonate (TEGDME-LiCF3SO3) electrolyte charged by various polysulfide species (Li2S2, Li2S4, Li2S6, and Li2S8) is here reported. We carefully detect the effects of lithium polysulfide addition by originally combining X-ray photoelectron spectroscopy (XPS) and electrochemical impedance spectroscopy (EIS). The measurements clearly reveal how the polysulfide addition affects the nature and composition of the solid electrolyte interphase (SEI) in terms of precipitated S-based species determined by XPS. The study demonstrates that the SEI layer formed on the Li anode decreases in impedance and stabilizes by the presence of polysulfide. This, together with a buffer effect strongly mitigating the sulfur-cathode dissolution and the shuttle reaction, significantly improves the stability of the lithium-sulfur cell. The data here reported clearly suggest the polysulfide as an effective additive to enhance the performance of the lithium-sulfur battery (Graph Presented).
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| 8. |
- Agostini, Marco, 1987, et al.
(författare)
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Rational Design of Low Cost and High Energy Lithium Batteries through Tailored Fluorine-free Electrolyte and Nanostructured S/C Composite
- 2018
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Ingår i: ChemSusChem. - : Wiley. - 1864-5631 .- 1864-564X. ; 11:17, s. 2981-2986
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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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| 9. |
- Agostini, Marco, 1987, et al.
(författare)
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Stabilizing the Performance of High-Capacity Sulfur Composite Electrodes by a New Gel Polymer Electrolyte Configuration
- 2017
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Ingår i: ChemSusChem. - : Wiley. - 1864-5631 .- 1864-564X. ; 10:17, s. 3490-3496
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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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| 10. |
- Aguilera Medina, Luis, 1983, et al.
(författare)
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A structural study of LiTFSI-tetraglyme mixtures: From diluted solutions to solvated ionic liquids
- 2015
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Ingår i: Journal of Molecular Liquids. - : Elsevier BV. - 0167-7322. ; 210:Part B, s. 238-242
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Tidskriftsartikel (refereegranskat)abstract
- We report on the nano-structure of solvated ionic liquids (SILs) formed by dissolving a Li-salt (LiTFSI) in the solvent tetraglyme. Using small angle X-ray scattering (SAXS), supported by Raman spectroscopy and computational modeling we follow how the nano-structure develops as Li-salt is added to the solvent. We find that, as the Li-salt concentration is increased a peak at Q 0.95 Å- 1 grows in intensity, signaling the presence of structural correlations typical of those found in traditional ionic liquids. The intensity of the peak reaches its maximum at the equimolar concentration, where each Li-ion can be solvated by one solvent molecule forming an effective cation complex. Combining the SAXS data with computer modeling we show that this peak can be assigned to charge alternation, also found in traditional ionic liquids. However, we also show that even at the equimolar concentration not all Li-ions are solvated by the solvent molecules, but a small fraction interacts directly with the anion (TFSI).
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