| 1. |
- Asfaw, Habtom D., Dr. 1986-, et al.
(författare)
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Bio-derived hard carbon nanosheets with high rate sodium-ion storage characteristics
- 2022
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Ingår i: Sustainable Materials and Technologies. - : Elsevier. - 2214-9937. ; 32
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Tidskriftsartikel (refereegranskat)abstract
- Biomass is a sustainable precursor of hard carbons destined for use in sodium-ion batteries. This study explores the synthesis of hard carbon nanosheets (HCNS) from oxidized cork and impact of synthesis temperature on the hard carbon characteristics. An increase in the carbonization temperature from 1000 to 1500 °C generally leads to lower BET specific surface areas (~55 to 20 m2 g−1) and d002 interlayer spacing (~ 4.0 to 3.7 Å). The effect of synthesis temperature is reflected in the initial coulombic efficiency (iCE) which increases from 72% at 1000 °C to 88% at 1500 °C, as a result of the decrease in surface area, and structural defects in the hard carbon as verified using Raman scattering. The impact of cycling temperature (~25, 30 and 55 °C) on the rate capability and long-term cycling is investigated using high precision coulometry cycler. For a galvanostatic test at 20 mA g−1 and ~ 25 °C, a reversible capacity of 276 mAh g−1 is observed with an iCE of ~88%. Increasing cycling temperature enhances the rate performance, but slightly lowers the iCE (~86% at 30 °C and ~ 81% at 55 °C). At 20 mA g−1, the reversible capacities obtained at 30 °C and 55 °C are on average ~ 260 and ~ 270 mAh g−1, respectively. For constant-current constant-voltage (CCCV) tests conducted at 30 °C, reversible capacities ranging from 252 to 268, 247–252, and 237–242 mAh g−1 can be obtained at 10, 100, and 1000 mA g−1, respectively. The respective capacities obtained at 55 °C are about 272–290, 260–279, and 234–265 mAh g−1 at 10, 100 and 1000 mA g−1. The applicability of the HCNS electrodes is eventually evaluated in full-cells with Prussian white cathodes, for which a discharge capacity of 152 mAh g−1 is obtained with an iCE of ~90%.
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| 2. |
- Bolívar Caballero, José Juan, et al.
(författare)
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Advanced application of a geometry-enhanced 3D-printed catalytic reformer for syngas production
- 2023
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Ingår i: Energy Conversion and Management. - : Elsevier BV. - 0196-8904 .- 1879-2227. ; 287
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Tidskriftsartikel (refereegranskat)abstract
- Catalyst research on reforming processes for syngas production has mainly focused on the active metals and support materials, while the effect of the catalyst's geometry on the reforming reactions has been poorly studied. The application of 3D-printed materials with enhanced geometries has recently started to be studied in heterogeneous catalysis and is of interest to be implemented for reforming biomass and plastic waste to produce H2-rich syngas. In this study, a geometry-enhanced 3D-printed Ni/Al2O3/FeCrAl-based monolithic catalyst with a periodic open cellular structure (POCS) was designed and fabricated. The catalyst was used for batch steam reforming biomass pyrolysis volatiles for syngas production at different parameters (temperature and steam-to-carbon ratio). The results showed complete reforming of pyrolysis volatiles in all experimental cases, a high H2 yield of ≈ 7.6 wt% of biomass was obtained at the optimized steam-to-carbon ratio of 8 and a reforming temperature of 800 °C, which is a higher yield compared to other batch reforming tests reported in the literature. Moreover, CFD simulation results in COMSOL Multiphysics demonstrated that the POCS configuration improves the reforming of pyrolysis volatiles for tar/bio-oil reforming and H2 production thanks to enhanced mass and heat transfer properties compared to the regular monolithic single-channel configuration.
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| 3. |
- Dwibedi, Debasmita, et al.
(författare)
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Na2.32Co1.84(SO4)(3) as a new member of the alluaudite family of high-voltage sodium battery cathodes
- 2017
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Ingår i: Dalton Transactions. - : Royal Society of Chemistry (RSC). - 1477-9226 .- 1477-9234. ; 46:1, s. 55-63
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Tidskriftsartikel (refereegranskat)abstract
- Electrochemical energy storage has recently seen tremendous emphasis being placed on the large-scale (power) grid storage. Sodium-ion batteries are capable of achieving this goal with economic viability. In a recent breakthrough in sodium-ion battery research, the alluaudite framework (Na2Fe2(SO4)(3)) has been reported, with the highest Fe3+/Fe2+ redox potential (ca. 3.8 V, Barpanda, et al., Nat. Commun., 2014, 5, 4358). Exploring this high-voltage sodium insertion system, we report the discovery of Na2+2xCo2-x(SO4)(3) (x = 0.16) as a new member of the alluaudite class of cathode. Stabilized by low-temperature solid-state synthesis (T <= 350 degrees C),this novel Co-based compound assumes a monoclinic structure with C2/c symmetry, which undergoes antiferromagnetic ordering below 10.2 K. Isotypical to the Fe-homologue, it forms a complete family of solid-solution Na2+2x(Fe1-yCoy)(2-x)(SO4)(3) [ y = 0-1]. Ab initio DFT analysis hints at potential high voltage operation at 4.76-5.76 V (vs. Na), depending on the degree of desodiation involving a strong participation of the oxygen sub-lattice. With the development of safe organic electrolytes, Na2+2xCo2-x(SO4)(3) can work as a cathode material (similar to 5 V) for sodium-ion batteries.
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| 4. |
- Ganesan, Priya, et al.
(författare)
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Fluorine-Substituted Halide Solid Electrolytes with Enhanced Stability toward the Lithium Metal
- 2023
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Ingår i: ACS Applied Materials and Interfaces. - : American Chemical Society (ACS). - 1944-8244 .- 1944-8252. ; 15:32, s. 38391-38402
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Tidskriftsartikel (refereegranskat)abstract
- The high ionic conductivityand good oxidation stability of halide-basedsolid electrolytes evoke strong interest in this class of materials.Nonetheless, the superior oxidative stability compared to sulfidescomes at the expense of limited stability toward reduction and instabilityagainst metallic lithium anodes, which hinders their practical use.In this context, the gradual fluorination of Li2ZrCl6-x F x (0 & LE; x & LE; 1.2) is proposed to enhance thestability toward lithium-metal anodes. The mechanochemically synthesizedfluorine-substituted compounds show the expected distorted local structure(M2-M3 site disorder) and significant change in the overallLi-ion migration barrier. Theoretical calculations reveal an approximateminimum energy path for Li2ZrCl6-x F x (x = 0 and0.5) with an increase in the Li+ migration energy barrierfor Li2ZrCl5.5F0.5 in comparisonto Li2ZrCl6. However, it is found that the fluorine-substitutedcompound exhibits substantially lower polarization after 800 h oflithium stripping and plating owing to enhanced interfacial stabilityagainst the lithium metal, as revealed by density functional theoryand ex situ X-ray photoelectron spectroscopy, thanks to the formationof a fluorine-rich passivating interphase.
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| 5. |
- Gond, Ritambhara, et al.
(författare)
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A Lignosulfonate Binder for Hard Carbon Anodes in Sodium-Ion Batteries : A Comparative Study
- 2021
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Ingår i: ACS Sustainable Chemistry and Engineering. - : American Chemical Society. - 2168-0485. ; 9:37, s. 12708-
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Tidskriftsartikel (refereegranskat)abstract
- An important factor in the development of sodium-ion batteries (SIBs) is the use of cheap and sustainable materials. Sodium lignosulfonate, a lignin derivative, is demonstrated here as an attractive, "green", water-soluble, and potentially cost-effective binder for use in hard carbon anodes for SIBs. A comparison of its battery cycling performance is made against other binders including sodium carboxymethyl cellulose and lignin, obtained from the kraft process, as well as sodium alginate, derived from algae. Apart from lignin, which requires processing in N-methyl-2-pyrrolidone, the other three binders are water-soluble. Lignosulfonate shows comparable or better performance, with high capacity retention and stability, when using 1 M NaPF6 in propylene carbonate or ethylene carbonate:diethyl carbonate electrolytes for both half- and full-cells (against a Prussian white cathode). Further improvements are observed when including styrene-butadiene rubber as a co-binder. X-ray photoelectron spectroscopy demonstrates similar solid electrolyte interphase compositions after the initial sodium insertion for both lignosulfonate and carboxymethyl cellulose binders. However, after subsequent cycling, the surface layer composition and thickness are found to be dependent on the binder. For the lignosulfonate-based electrode, the layer appears thicker but comprises a smaller fraction of carbon-oxygen species. © 2021 The Authors.
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| 6. |
- Gond, Ritambhara, et al.
(författare)
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Enabling the Electrochemical Activity in Sodium Iron Metaphosphate [NaFe(PO3)(3)] Sodium Battery Insertion Material : Structural and Electrochemical Insights
- 2017
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Ingår i: Inorganic Chemistry. - : AMER CHEMICAL SOC. - 0020-1669 .- 1520-510X. ; 56:10, s. 5918-5929
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Tidskriftsartikel (refereegranskat)abstract
- Sodium-ion batteries are widely pursued as an economic alternative to lithium-ion battery technology, where Fe- and Mn-based compounds are particularly attractive owing to their elemental abundance. Pursuing phosphate-based polyanionic chemistry, recently solid-state prepared NaFe(PO3)(3) metaphosphate was unveiled as a novel potential sodium insertion material, although it was found to be electrochemically inactive. In the current work, employing energy-savvy solution combustion synthesis, NaFe2+(PO3)(3) was produced from low-cost Fe3+ precursors. Owing to the formation of nanoscale carbon-coated product, electrochemical activity was enabled in NaFe(PO3)(3) for the first time. In congruence with the first principles density functional theory (DFT) calculations, an Fe3+/Fe2+ redox activity centered at 2.8 V (vs Na/Na+) was observed. Further, the solid-solution metaphosphate family Na(Fe1-xMnx)(PO3)(3) (x = 0-1) was prepared for the first time. Their structure and distribution of transition metals (TM = Fe/Mn) was analyzed with synchrotron diffraction, X-ray photoelectron spectroscopy, and Mossbauer spectroscopy. Synergizing experimental and computational tools, NaFe(PO3)(3) metaphosphate is presented as an electrochemically active sodium insertion host material.
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| 7. |
- Gond, Ritambhara, et al.
(författare)
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Non-flammable liquid electrolytes for safe batteries
- 2021
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Ingår i: Materials Horizons. - : Royal Society of Chemistry. - 2051-6347 .- 2051-6355. ; 8:11, s. 2913-2928
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Tidskriftsartikel (refereegranskat)abstract
- With continual increments in energy density gradually boosting the performance of rechargeable alkali metal ion (e.g. Li+, Na+, K+) batteries, their safe operation is of growing importance and needs to be considered during their development. This is essential, given the high-profile incidents involving battery fires as portrayed by the media. Such hazardous events result from exothermic chemical reactions occurring between the flammable electrolyte and the electrode material under abusive operating conditions. Some classes of non-flammable organic liquid electrolytes have shown potential towards safer batteries with minimal detrimental effect on cycling and, in some cases, even enhanced performance. This article reviews the state-of-the-art in non-flammable liquid electrolytes for Li-, Na- and K-ion batteries. It provides the reader with an overview of carbonate, ether and phosphate-based organic electrolytes, co-solvated electrolytes and electrolytes with flame-retardant additives as well as highly concentrated and locally highly concentrated electrolytes, ionic liquids and inorganic electrolytes. Furthermore, the functionality and purpose of the components present in typical non-flammable mixtures are discussed. Moreover, many non-flammable liquid electrolytes are shown to offer improved cycling stability and rate capability compared to conventional flammable liquid electrolytes.
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| 8. |
- Gond, Ritambhara, et al.
(författare)
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Phosphate-based polyanionic insertion materials for oxygen electrocatalysis
- 2024
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Ingår i: Materials Chemistry Frontiers. - : Royal Society of Chemistry. - 2052-1537. ; 8:5, s. 1153-1170
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Forskningsöversikt (refereegranskat)abstract
- Electrocatalyst-based energy storage technologies such as alkali metal–air batteries, fuel cells, and water splitting devices are the new holy grail in the next-generation energy storage landscape as they deliver higher energy densities than Li-ion/Na-ion batteries (LIBs/SIBs). The new chemistries of energy storage such as metal–air batteries under aqueous or non-aqueous conditions will complement existing LIBs/SIBs owing to the increasing requirement for batteries with high energy density in the present era. Phosphate-based polyanionic frameworks have long been known for their ability to (de)intercalate alkali metal ions. Because of their innate oxygen electrocatalytic activity, these insertion cathode materials have lately emerged as air electrodes in metal–air battery systems. In this review, the present status of phosphate-based polyanionic insertion materials for oxygen reduction and oxygen evolution reaction (ORR and OER) electrocatalysis is summarized. Factors influencing electrocatalytic activity in these materials, such as the presence of different types of alkali metal cations, transition metals, and the type of ligand/mixed anion as well as coordination around the transition metals are discussed. Finally, the development of metal–air batteries derived from phosphate-based polyanionic insertion materials as air electrodes is discussed.
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| 9. |
- Gond, Ritambhara, et al.
(författare)
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Pyrophosphate Na2CoP2O7 Polymorphs as Efficient Bifunctional Oxygen Electrocatalysts for Zinc-Air Batteries
- 2022
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Ingår i: ACS Applied Materials and Interfaces. - : American Chemical Society (ACS). - 1944-8244 .- 1944-8252. ; 14:36, s. 40761-40770
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Tidskriftsartikel (refereegranskat)abstract
- Developing earth-abundant low-cost bifunctional oxygen electrocatalysts is a key approach to realizing efficient energy storage and conversion. By exploring Co-based sodium battery materials, here we have unveiled nanostructured pyrophosphate Na2CoP2O7 polymorphs displaying efficient bifunctional electrocatalytic activity. While the orthorhombic polymorph (oNCPy) has superior oxygen evolution reaction (OER) activity, the triclinic polymorph (t-NCPy) delivers better oxygen reduction reaction (ORR) activity. Simply by tuning the annealing condition, these pyrophosphate polymorphs can be easily prepared at temperatures as low as 500 degrees C. The electrocatalytic activity is rooted in the Co redox center with the (100) active surface and stable structural framework as per ab initio calculations. It marks the first case of phospho-anionic systems with both polymorphs showing stable bifunctional activity with low combined overpotential (ca. similar to 0.7 V) comparable to that of reported state-of-the-art catalysts. These nanoscale cobalt pyrophosphates can be implemented in rechargeable zinc-air batteries.
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| 10. |
- Jamal, Ali, et al.
(författare)
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Tris(trimethylsilyl) Phosphite and Lithium Difluoro(oxalato)borate as Electrolyte Additives for LiNi0.5Mn1.5O4-Graphite Lithium-Ion Batteries
- 2023
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Ingår i: ChemElectroChem. - : Wiley-VCH Verlagsgesellschaft. - 2196-0216. ; 10:16
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Tidskriftsartikel (refereegranskat)abstract
- Raising the energy density of lithium-ion batteries (LIBs) through the operation of high-voltage cathodes presents a challenge in terms of practical use due to electrolyte degradation. Consequently, it is imperative to explore new materials to circumvent this issue. In this study, a combination of tris(trimethylsilyl) phosphite (TMSPi) and lithium difluoro(oxalato)borate (LiDFOB) is presented as film-forming additives in a conventional LiPF6-containing carbonate-based electrolyte solution in high-voltage LiNi0.5Mn1.5O4-graphite full cells. At high voltage, TMSPi oxidizes on the LiNi0.5Mn1.5O4 (LNMO) cathode surface prior to the decomposition of electrolyte solvents, promoting the formation of a stable cathode electrolyte interphase (CEI) layer. In tandem, given that LiDFOB has a lower reduction potential than ethylene carbonate (EC), it has the possibility of forming a solid electrolyte interphase (SEI) on the graphite anode surface. Combining the two additives was found to suppress the degradation of the electrolyte to a large extent. Among the investigated concentration of the additives, the combination of 1 wt. % TMSPi and 2 wt. % LiDFOB added to LP40 electrolyte exhibits improved capacity retention of 80 % after 400 cycles at 0.3 C, compared to the electrolyte with no additive with 67 % capacity retention over the same period. Thereby, the combination of TMSPi with LiDFOB provides an improvement for high voltage LIBs.
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