I18-Microfocus Spectroscopy
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Thomas
Barthelay
,
Robert
Gray
,
Howard
Richards
,
Paloma
Rodriguez Santana
,
Sylvia
Britto
,
Kalotina
Geraki
,
Zhenyuan
Xia
,
Johanna
Xu
,
Leif E.
Asp
,
Chris
Bowen
,
Frank
Marken
,
Alexander
Lunt
,
Andrew
Rhead
Diamond Proposal Number(s):
[30127]
Open Access
Abstract: Structural batteries utilise the bifunctionality of carbon fibres to act as a load-bearing structure, but also as a conductive current collector for a battery electrode. Lithium-ion transport during the cycling of structural battery cathodes coated with different morphologies is investigated using Iron X-Ray Absorption Near Edge Spectroscopy (Fe XANES) and correlated to electrochemical performance. Two contrasting morphologies were produced using slurry coating and electrophoretic deposition (EPD) of lithium-iron phosphate (LFP) onto continuous carbon fibres. The ability to study the different structural battery cathode morphologies operando allows for a comparative analysis of their impact on cycling performance. The EPD-coated fibres exhibited a more homogeneous, thinner coating around the fibre compared to the thick, one-sided coating produced using slurry coating. Despite a lower initial capacity and 30 % lithium re-intercalation loss in the first cycle, EPD-coated fibres exhibited more stable capacity retention over time compared to slurry-coated counterparts. Electrochemical Impedance Spectroscopy (EIS) revealed initially high ionic resistance for the EPD-coated fibres, but a larger increase in resistance in the slurry coated electrodes over multiple cycles. This study demonstrated an innovative and novel method of analysing in greater detail, the cycling ability of the coated cathode material on carbon fibres using synchrotron radiation.
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Feb 2025
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I07-Surface & interface diffraction
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Diamond Proposal Number(s):
[32266]
Abstract: Organic solar cells (OSCs) are attracting significant attention due to their low cost, lightweight, and flexible nature. The introduction of nonfullerene acceptors (NFAs) has propelled OSC development into a transformative era. However, the limited availability of wide band gap polymer donors for NFAs poses a critical challenge, hindering further advancements. This study examines the role of developed wide band gap halogenated pyrrolo[3,4-c]pyrrole-1,3(2H,5H)-dione (PPD)-based polymers, in combination with the Y6 nonfullerene acceptor, in bulk heterojunction (BHJ) OSCs. We first focus on the electronic and absorbance modifications brought about by halogen substitution in PPD-based polymers, revealing how these adjustments influence the HOMO/LUMO energy levels and, subsequently, photovoltaic performance. Despite the increased Voc of halogenated polymers due to the optimal band alignment, power conversion efficiencies (PCEs) were decreased due to suboptimal blend morphologies. We second implemented PPD as a solid additive to PM6:Y6, forming ternary OSCs and further improving the PCE. The study provides a nuanced understanding of the interplay between molecular design, device morphology, and OSC performance and opens insights for future research to achieve an optimal balance between band alignment and favorable blend morphology for high-efficiency OSCs.
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Jan 2025
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I11-High Resolution Powder Diffraction
I19-Small Molecule Single Crystal Diffraction
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Diamond Proposal Number(s):
[30461, 31578]
Abstract: Batteries are a critical technology for the transition to a sustainable energy economy. Rechargeable lithium ion (Li ion) batteries power our electronic devices and electric cars and are needed to store energy generated from renewable sources. The design and discovery of new materials underpins the development of high performing and reliable rechargeable batteries that are long-lasting, cost-effective, fast charging, safe and sustainable. Most Li-ion batteries rely on a liquid electrolyte to conduct ions between the anode and cathode. However, liquid electrolytes can leak and are flammable, which can lead to fires. One solution to this issue is to use a solid electrolyte, and researchers at the University of Liverpool have discovered a solid material with high enough Li ion conductivity to replace the liquid electrolytes in current Li ion battery technology, improving safety and energy capacity. Their work, recently published in Science, used a collaborative computational and experimental workflow, synthesising the material in the laboratory, using synchrotron techniques to determine its structure, and demonstrating it in a battery cell. Their disruptive design approach offers a new route to discover more high-performance materials that rely on the fast motion of ions in solids.
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Jan 2025
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I21-Resonant Inelastic X-ray Scattering (RIXS)
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Diamond Proposal Number(s):
[32023]
Open Access
Abstract: Activation of oxygen anion redox represents an effective method of increasing the specific capacity as well as raising the operating voltage of layered sodium transition metal oxides. However, these reactions are often accompanied by irreversible structural transformations and detrimental side‑reactions between the electrolyte and electrode interface which accelerate degradation, thereby impeding their practical application. To optimise the oxygen anion reversibility for practical use and compare the effects of dopants, we investigated Zn- and Ti-substitution both separately and combined in P3‑structure Na0.7Mn0.75Ni0.25O2, assisted by DFT calculations. The Zn-substituted materials, Na0.7Mn0.65Ni0.25Zn0.1O2 and Na0.7Mn0.58Ni0.25Zn0.07Ti0.1O2 present superior cycling stability over the high voltage range 3.8-4.3 V and enhanced rate capability, delivering a reversible capacity of ~80 mA h g‑1 at 500 mA g‑1 over the voltage window 2.2‑4.3 V compared with 58.6 mA h g-1 for the parent-phase. The improved electrochemical performance of the Zn-substituted materials is attributed to suppression of the P3 to O’3 phase transformation revealed by X‑ray diffraction and the lower electronegativity and filled d ‑band of Zn. The presence of TiO6 octahedra in the Ti-substituted materials relieves structural distortions/TM ordering, also improving the cycling stability. With Zn/Ti co-substitution these advantages may be combined, as demonstrated by the superior electrochemical performance observed for Na0.7Mn0.58Ni0.25Zn0.07Ti0.1O2.
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Jan 2025
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I14-Hard X-ray Nanoprobe
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Ruwei
Chen
,
Yunpeng
Zhong
,
Peie
Jiang
,
Hao
Tang
,
Fei
Guo
,
Yuhang
Dai
,
Jie
Chen
,
Jingyi
Wang
,
Jiyang
Liu
,
Song
Wei
,
Wei
Zhang
,
Wei
Zong
,
Fangjia
Zhao
,
Jichao
Zhang
,
Zhengxiao
Guo
,
Xiaohui
Wang
,
Guanjie
He
Diamond Proposal Number(s):
[36785]
Open Access
Abstract: Long-standing challenges including notorious side reactions at the Zn anode, low Zn anode utilization, and rapid cathode degradation at low current densities hinder the advancement of aqueous zinc-ion batteries (AZIBs). Inspired by the critical role of capping agents in nanomaterials synthesis and bulk crystal growth, a series of capping agents are employed to demonstrate their applicability in AZIBs. Here, it is shown that the preferential adsorption of capping agents on different Zn crystal planes, coordination between capping agents and Zn2+ ions, and interactions with metal oxide cathodes enable preferred Zn (002) deposition, water-deficient Zn2+ ion solvation structure, and a dynamic cathode-electrolyte interface. Benefiting from the multi-functional role of capping agents, dendrite-free Zn plating and stripping with an improved Coulombic efficiency of 99.2% and enhanced long-term cycling stability are realized. Remarkable capacity retention of 91% is achieved for cathodes after more than 500 cycles under a low current density of 200 mA g−1, marking one of the best cycling stabilities to date. This work provides a proof-of-concept of capping agents in manipulating electrochemical behaviors, which should inspire and pave a new avenue of research to address the challenges in practical energy storage beyond AZIBs.
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Jan 2025
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I07-Surface & interface diffraction
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Diamond Proposal Number(s):
[36553]
Open Access
Abstract: The efficiency of organic solar cells has raised drastically in the past years. However, there is an undeniable lack of hole transport layers that can provide high carrier selectivity, low defect density, and high processing robustness, simultaneously. In this work, this issue is addressed by studying defect generation and surface passivation of nickel oxide (NiOx). It is revealed that the generation of high oxidation state species on NiOx surface lowers contact resistance but hinders charge extraction when employed as transport layer in organic solar cells. By using them as coordination centers, a straightforward surface modification strategy is implemented using (2-(9H-carbazol-9-yl)ethyl)phosphonic acid (2PACz) that enhances charge extraction and increases the solar cell efficiency from 11.46% to 17.12%. Additionally, the robustness of this modification across different deposition methods of the carbazole molecule is demonstrated. Finally, by fine-tuning the Fermi level using various carbazole-based molecules, and in particular with ((4-(7H-dibenzo[c,g]carbazol-7-yl)butyl)phosphonic acid (4PADCB), a power conversion efficiency of 17.29% is achieved, with an outstanding combination of a VOC of 0.888 V and a fill factor of 80%.
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Jan 2025
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I09-Surface and Interface Structural Analysis
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Diamond Proposal Number(s):
[33024]
Open Access
Abstract: With the increasing attention to energy storage solutions, a growing emphasis has been placed on environmentally compatible electrolytes tailored for lithium-ion batteries. This study investigates the surface behavior of Si wafers as model systems cycled with a fluorine-free electrolyte based on lithium bis(oxalato)borate (LiBOB), with and without the additive vinylene carbonate (VC). By utilizing operando X-ray reflectivity (XRR) and ex situ X-ray photoelectron spectroscopy (XPS), the intricate processes involved in solid electrolyte interphase (SEI) formation is elucidated, SiO2/Si (de)lithiation, and the impact of the VC additive. Three distinct stages in SEI evolution during lithiation and delithiation are identified: SEI formation, subsequent densification and growth, and decrease in SEI thickness during delithiation, which collectively demonstrate the breathing behavior of the SEI during cycling. The addition of VC is found to mitigate LiBOB decomposition during cycling and promote a smoother SEI layer. Moreover, lithium trapping within the Si wafer post-delithiation is observed for both electrolytes but to a lesser extent with the addition of VC. This study offers structural and chemical insights into the fundamental processes governing SEI formation and Si wafer (de)lithiation in LiBOB-based electrolytes, with implications for designing environmentally friendly lithium-ion batteries.
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Jan 2025
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B18-Core EXAFS
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Diamond Proposal Number(s):
[36104]
Abstract: The sulfion oxidation reaction (SOR) assisted seawater electrolysis has been proposed to be a potentially cost-effective approach to hydrogen production because SOR happens at an anodic potential significantly lower than that of the energy-demanding oxygen evolution reaction (OER). However, the key to unleash full potential of SOR for practical seawater electrolysis is to develop highly efficient and stable electrocatalysts able to sustain in harsh seawater environment at high current densities. Herein, we report the fabrication of nickel foam supported nickel telluride nanorod arrays covered conformally with an electrodeposited amorphous nickel molybdenum layer (NiTe@NiMo/NF), which exhibit outstanding SOR performance, capable of delivering 500 mA cm−2 at only 0.55 V vs. reversible hydrogen electrode (RHE) and operating at 500 mA cm−2 for 100 hours without degradation, in both simulated and natural seawater. Our comprehensive experimental and theoretical studies reveal that the NiTe@NiMo/NF electrode undergoes a dynamic reconstruction process, and the in-situ generated [MoO4]2− moieties can modulate and stabilize the catalytically active NiTe/NiOOH, improving the SOR activity and stability. Consequently, the asymmetric membrane electrode assembly comprising NiTe@NiMo/NF as the anode can deliver a current density as large as 5.0 A cm−2 at 1.33 V in alkaline natural seawater at 70 °C and operate at 1.0 A cm−2 below 1.0 V for 334 hours, holding great potential for energy-saving and cost-competitive hydrogen production from seawater.
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Dec 2024
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B18-Core EXAFS
I11-High Resolution Powder Diffraction
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Diamond Proposal Number(s):
[33172, 34243]
Open Access
Abstract: We investigate magnesium–iron pyroborate MgFeB2O5 as a potential cathode material for rechargeable magnesium-ion batteries. Synchrotron powder X-ray diffraction and Mössbauer spectroscopy confirm its successful synthesis and iron stabilization in the high-spin Fe(II) state. Initial electrochemical testing against a lithium metal anode yields a first charge capacity near the theoretical value (147.45 mAh·g–1), suggesting MgFeB2O5 as a promising cathode candidate. However, multimodal analyses, including scanning electron microscopy energy-dispersive X-ray (SEM-EDS) analysis, operando X-ray absorption near edge spectroscopy (XANES), and Mössbauer spectroscopy, reveal the absence of any Fe redox reactions. Instead, we propose that the source of the observed capacity involves the irreversible reaction of a small (4–7 wt%) Fe metal impurity. These findings highlight the need for diverse characterization techniques in evaluating the performance of new Mg cathode materials, since promising initial cycling may be caused by competing side reactions rather than Mg (de)intercalation.
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Dec 2024
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E02-JEM ARM 300CF
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Sangcheol
Yoon
,
Braulio
Reyes-Suárez
,
Sang T.
Pham
,
Hervé
Vezin
,
Yeny A.
Tobon
,
Myeongjae
Lee
,
Sam
Mugiraneza
,
Brian Minki
Kim
,
Mariane Yuka Tsubaki
Oide
,
Seongju
Yoo
,
Seunggu
Lee
,
Shu Hui
Wang
,
Sean M.
Collins
,
Christopher M.
Bates
,
Yongsup
Park
,
Bongsoo
Kim
,
G. N. Manjunatha
Reddy
,
Thuc-Quyen
Nguyen
Diamond Proposal Number(s):
[34607]
Abstract: Understanding efficiency–durability relationships and related mitigation strategies is an important step toward the commercialization of organic photovoltaics (OPVs). Here, we report that a photoactivated 6-bridged azide cross-linker (6Bx) improves the morphological stability by suppressing the thermally activated diffusion of (Y6) acceptor molecules in PM6:Y6 bulk-heterojunction (BHJ)-based OPVs. Cross-linked PM6:Y6 (0.05 wt % 6Bx) BHJ OPVs retain 93.4% of the initial power conversion efficiency upon thermal aging at 85 °C for 1680 h (T80 = 3290 h). Molecular origins of enhanced thermal stability are corroborated by optical spectroscopy, surface imaging, 2D solid-state nuclear magnetic resonance (ssNMR), Raman spectroscopy, scanning electron diffraction (SED) measurements, and analysis of the BHJ thin films. The facile single-step cross-linking strategy in conjugation with advanced characterization methods presented in the study paves the way toward developing durable OPVs based on non-fullerene acceptors (NFAs).
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Dec 2024
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