468 results match your criteria: "Helmholtz Institute Ulm[Affiliation]"

Based on quantum chemical calculations, we predict strong solvatochromism in a light-driven molecular photocatalyst for hydrogen generation, that is we show that the electronic and optical properties of the photocatalyst strongly depend on the solvent it is dissolved in. Our calculations in particular indicate a solvent-dependent relocation of the highest occupied molecular orbital (HOMO). Ground-state density functional theory and linear response time-dependent density functional theory calculations were applied in order to investigate the influence of implicit solvents on the structural, electronic and optical properties of a molecular photocatalyst.

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Article Synopsis
  • Poly(ethylene oxide) (PEO) faces challenges like limited ionic conductivity and a narrow electrochemical window, which impacts its use in high-energy-density lithium metal batteries.
  • An innovative hybrid filler-enhanced solid polymer electrolyte (SPE) has been developed to improve electrochemical performance for lithium metal anodes and LiFePO cathodes, achieving high ionic conductivity and transference numbers.
  • The composite membrane shows impressive stability and performance, evidenced by 2000 hours of operation in symmetric cells and a high-capacity retention in batteries after 400 cycles, indicating that combining active and inactive fillers can boost solid-state battery performance.
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Sn-based anodes are promising high-capacity anode materials for low-cost lithium ion batteries. Unfortunately, their development is generally restricted by rapid capacity fading resulting from large volume expansion and the corresponding structural failure of the solid electrolyte interphase (SEI) during the lithiation/delithiation process. Herein, heterostructural core-shell SnO-layer-wrapped Sn nanoparticles embedded in a porous conductive nitrogen-doped carbon (SOWSH@PCNC) are proposed.

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Given the increasing energy storage demands and limited natural resources of Li, K-ion batteries (KIBs) could be promising next-generation systems having natural abundance, similar chemistry, and energy density. Here, we have investigated the P3-type KTMO (where TM = Ti, V, Cr, Mn, Co, or Ni) systems using density functional theory calculations as potential positive intercalation electrodes (or cathodes) for KIBs. Specifically, we have identified ground-state configurations and calculated the average topotactic voltages, electronic structures, on-site magnetic moments, and thermodynamic stabilities of all P3-KTMO compositions and their corresponding depotassiated P3-TMO frameworks.

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Delocalized Isoelectronic Heterostructured FeCoO S Catalysts with Tunable Electron Density for Accelerated Sulfur Redox Kinetics in Li-S batteries.

Angew Chem Int Ed Engl

November 2023

Institute for Innovative Materials and Energy, Faculty of Chemistry and Chemical Engineering, Yangzhou University, Yangzhou, 225002, China.

High interconversion energy barriers, depressive reaction kinetics of sulfur species, and sluggish Li transport inhibit the wide development of high-energy-density lithium sulfur (Li-S) batteries. Herein, differing from random mixture of selected catalysts, the composite catalyst with outer delocalized isoelectronic heterostructure (DIHC) is proposed and optimized, enhancing the catalytic efficiency for decreasing related energy barriers. As a proof-of-content, the FeCoO S composites with different degrees of sulfurization are fabricated by regulating atoms ratio between O and S.

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Investigating the Influence of Treatments on Carbon Felts for Vanadium Redox Flow Batteries.

ChemSusChem

January 2024

Faculty of Engineering, Department of Electrical, Electronics, Communication Engineering, Friedrich-Alexander-Universität Erlangen-Nürnberg (FAU), Cauerstraße 9, 91058, Erlangen, Germany.

Vanadium redox flow battery (VRFB) electrodes face challenges related to their long-term operation. We investigated different electrode treatments mimicking the aging processes during operation, including thermal activation, aging, soaking, and storing. Several characterization techniques were used to deepen the understanding of the treatment of carbon felts.

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Transference numbers play an important role in understanding the dynamics of electrolytes and assessing their performance in batteries. Unfortunately, these transport parameters are difficult to measure in highly concentrated liquid electrolytes such as ionic liquids. Also, the interpretation of their sign and magnitude has provoked an ongoing debate in the literature further complicated by the use of different languages.

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Stabilizing Decavanadate Cluster as Electrode Material in Sodium and Lithium-ion Batteries.

ChemSusChem

December 2023

Institute of Inorganic Chemistry I, Ulm University, Albert-Einstein-Allee 11, D-89081, Ulm, Germany.

Decavanadate ([V O ] , {V }) clusters are a potential electrode material for lithium and post-lithium batteries; however, their low stability due to the solubility in liquid organic electrolytes has been challenging. These molecular clusters are also prone to transform into solid-state oxides at a moderate temperature needed in the typical electrode fabrication process. Hence, controlling the solubility and improving the thermal stability of compounds are essential to make them more viable options for use as battery electrodes.

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Article Synopsis
  • Manganese hexacyanoferrate shows potential as a cathode material for lithium and sodium ion batteries but experiences capacity loss during cycling.
  • Researchers used transmission soft X-ray microscopy to analyze fresh and cycled electrodes at a nanometer scale, focusing on elements like manganese, iron, and nitrogen.
  • Findings revealed increased structural inhomogeneities in aged electrodes, especially in lithium-ion batteries, indicating that redox coupling and electron delocalization may affect performance and cycle life.
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This study presents a green, ultra-fast, and facile technique for the fabrication of micro/nano-structured and porous Cu electrodes through in-liquid plasma electrolysis using phosphorous-oxoanion-based electrolytes. Besides the preferential surface faceting, the Cu electrodes exhibit unique surface structures, including octahedral nanocrystals besides nanoporous and microporous structures, depending on the employed electrolyte. The incorporation of P-atoms into the Cu surfaces is observed.

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Article Synopsis
  • Understanding the modeling of water-in-salt (WiS) electrolytes for battery applications involves considering the impact of polarization on atomic interactions in molecular dynamics (MD) simulations.
  • Different approaches to include polarization range from nonpolarizable force fields, which simplify by averaging effects, to explicit polarization methods like the Drude oscillator model, enhancing accuracy but increasing computational demand.
  • This study determines that a combination of the Drude polarizable force field for salt ions and non-polarizable models for water balances accuracy and computational efficiency, enabling reliable simulation of electrolyte properties while allowing flexibility in force field parameters.
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The high ionic conductivity and good oxidation stability of halide-based solid electrolytes evoke strong interest in this class of materials. Nonetheless, the superior oxidative stability compared to sulfides comes at the expense of limited stability toward reduction and instability against metallic lithium anodes, which hinders their practical use. In this context, the gradual fluorination of LiZrClF (0 ≤ ≤ 1.

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Calcium (Ca) batteries are attractive post-lithium battery technologies, due to their potential to provide high-voltage and high-energy systems in a sustainable manner. We investigated herein 1,5-poly(anthraquinonylsulfide) (PAQS) for Ca-ion storage with calcium tetrakis(hexafluoroisopropyloxy)borate Ca[B(hfip) ] [hfip=OCH(CF ) ] electrolytes. It is demonstrated that PAQS could be synthesized in a cost-effective approach and be processed environmentally friendly into the electrodes.

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All-Organic Battery Based on Deep Eutectic Solvent and Redox-Active Polymers.

ChemSusChem

January 2024

Institute of Electrochemistry, Ulm University, Albert-Einstein-Allee 47, 89081, Ulm, Germany.

Sustainable battery concepts are of great importance for the energy storage demands of the future. Organic batteries based on redox-active polymers are one class of promising storage systems to meet these demands, in particular when combined with environmentally friendly and safe electrolytes. Deep Eutectic Solvents (DESs) represent a class of electrolytes that can be produced from sustainable sources and exhibit in most cases no or only a small environmental impact.

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Sodium-metal batteries (SMBs) are considered a potential alternative to high-energy lithium-metal batteries (LMBs). However, the high reactivity of metallic sodium towards common liquid organic electrolytes renders such battery technology particularly challenging. Herein, we propose a multi-block single-ion conducting polymer electrolyte (SIPE) doped with ethylene carbonate as suitable electrolyte system for SMBs.

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Development of highly efficient, earth-abundant, and stable bifunctional electrocatalysts is pivotal for designing viable next-generation metal-air batteries. Cobalt-based phosphates provide a treasure house to design electrocatalysts, with a wide range of cation substitutions to further enhance their electrocatalytic activity. In particular, phosphates with distorted geometry show favorable binding efficiency toward water molecules with low overpotential.

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Rechargeable aqueous zinc-metal batteries (AZBs) are a promising complimentary technology to the existing lithium-ion batteries and the re-emerging lithium-metal batteries to satisfy the increasing demands on energy storage. Despite considerable progress achieved in the past years, the fundamental understanding of the solid-electrolyte interphase (SEI) formation and how its composition influences the SEI properties are limited. This review highlights the functionalities of anion-tuned SEI on the reversibility of zinc-metal anode, with a specific emphasis on new structural insights obtained through advanced characterizations and computational techniques.

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The production of renewable feedstocks through the coupled oxygen evolution reaction (OER) with selective organic oxidation requires a perfect balance in the choice of a catalyst and its synthesis access, morphology, and catalytic activity. Herein we report a rapid plasma approach to produce a hierarchical amorphous birnessite-type manganese oxide layer on 3D nickel foam. The as-prepared anode exhibits an OER activity with overpotentials of 220, 250, and 270 mV for 100, 500, and 1000 mA·cm, respectively, and can spontaneously be paired with chemoselective dehydrogenation of benzylamine under both ambient and industrial (6 M KOH, 65 °C) alkaline conditions.

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In the search for post-lithium battery systems, magnesium-sulfur batteries have attracted research attention in recent years due to their high potential energy density, raw material abundance, and low cost. Despite significant progress, the system still lacks cycling stability mainly associated with the ongoing parasitic reduction of sulfur at the anode surface, resulting in the loss of active materials and passivating surface layer formation on the anode. In addition to sulfur retention approaches on the cathode side, the protection of the reductive anode surface by an artificial solid electrolyte interphase (SEI) represents a promising approach, which contrarily does not impede the sulfur cathode kinetics.

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Unlabelled: MnO nano-octahedrons embedded in N-doped graphene oxide (MNGO) nanosheets were synthesized using a simple, energy-efficient, and rapid microwave-digested hydrothermal route in a single step. The structural and morphological aspects of synthesized materials were evaluated by XRD, IR, Raman, FE-SEM, and HR-TEM techniques. Then, the composite MNGO was tested for its Li-ion storage properties and compared with reduced graphene oxide (rGO) and MnO materials.

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This study addresses the improved cycling stability of Li-ion batteries based on Fe-Ti-doped LiNi Mn O (LNMO) high-voltage cathode active material and graphite anodes. By using 1 wt% Li PO as cathode additive, over 90% capacity retention for 1000 charge-discharge cycles and remaining capacities of 109 mAh g are reached in a cell with an areal capacity of 2.3 mAh cm (potential range: 3.

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The lithium-metal anode is a promising candidate for realizing high-energy-density batteries owing to its high capacity and low potential. However, several rate-limiting kinetic obstacles, such as the desolvation of Li solvation structure to liberate Li , Li nucleation, and atom diffusion, cause heterogeneous spatial Li-ion distribution and fractal plating morphology with dendrite formation, leading to low Coulombic efficiency and depressive electrochemical stability. Herein, differing from pore sieving effect or electrolyte engineering, atomic iron anchors to cation vacancy-rich Co S embedded in 3D porous carbon (SAFe/CVRCS@3DPC) is proposed and demonstrated as catalytic kinetic promoters.

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A trace amount of water is typically unavoidable as an impurity in ionic liquids, which is a huge challenge for their application in Mg-ion batteries. Here, we employed molecular sieves of different pore diameters (3, 4, and 5 Å), to effectively remove the trace amounts of water from 1-methyl-1-propylpiperidinium bis(trifluoromethylsulfonyl)imide (MPPip-TFSI) and 1-butyl-1-methylpyrrolidinium bis(trifluoromethylsulfonyl)imide (BMP-TFSI). Notably, after sieving (water content <1 mg ⋅ L ), new anodic peaks arise that are attributed to the formation of different anion-cation structures induced by minimizing the influence of hydrogen bonds.

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Localised degradation within sulfide-based all-solid-state electrodes visualised by Raman mapping.

Chem Commun (Camb)

June 2023

Stephenson Institute for Renewable Energy, Department of Chemistry, University of Liverpool, Liverpool L69 7ZF, UK.

The distribution of degradation products, before and after cycling, within common sulfide-based solid electrolytes (β-LiPS, LiPSCl and LiGePS) was mapped using Raman microscopy. All composite electrodes displayed the appearance of side reaction products after the initial charge-discharge cycle, located at the site of a LiNiMnCoO particle.

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Origin of Heterogeneous Stripping of Lithium in Liquid Electrolytes.

ACS Nano

June 2023

Institute of Engineering Thermodynamics, German Aerospace Center (DLR), Wilhelm-Runge-Str. 10, 89081 Ulm, Germany.

Lithium metal batteries suffer from low cycle life. During discharge, parts of the lithium are not stripped reversibly and remain isolated from the current collector. This isolated lithium is trapped in the insulating remaining solid-electrolyte interphase (SEI) shell and contributes to the capacity loss.

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