B07-B1-Versatile Soft X-ray beamline: High Throughput ES1
I09-Surface and Interface Structural Analysis
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Nickil
Shah
,
Galo J.
Paez Fajardo
,
Hrishit
Banerjee
,
Gaurav C.
Pandey
,
Ashok S.
Menon
,
Muhammad
Ans
,
Veronika
Majherova
,
Gerard
Bree
,
Satish
Bolloju
,
David .
Grinter
,
Pilar
Ferrer
,
Pardeep K.
Thakur
,
Tien-Lin
Lee
,
Melanie
Loveridge
,
Andrew J.
Morris
,
Clare P.
Grey
,
Louis F. J.
Piper
Diamond Proposal Number(s):
[30201, 33459]
Open Access
Abstract: In Ni-rich layered oxide cathodes, cycling above the oxygen-loss threshold voltage (∼4.3 V vs Li+/Li) promotes structural transformations at the cathode surface. These transformations can result in various thermodynamically favorable rocksalt-like (RSL) structures (NiO, NiOx, and/or LiyNizO) that have different Li+ transport properties. Elucidating the precise phase type in the RSL can help determine design strategies to improve Li+ kinetics and identify design rules to suppress capacity fade in Ni-rich cathodes. This study utilizes surface-sensitive X-ray absorption spectroscopy in combination with first-principles simulations and distinguishes the layered oxide spectroscopic features from those of surface-reduced layers of pure NiO and LixNi1–xO. The transport of lithium ions through this oxygen-loss-induced surface-reconstructed layer is studied with operando X-ray diffraction in a pouch cell as a function of cycling aging and constant voltage protocols.
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Feb 2025
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I14-Hard X-ray Nanoprobe
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Dominic
Blackburn
,
Nathan S.
Hill
,
Christopher J.
Wood
,
Tamilselvan
Velusamy
,
Balder A.
Nieto-Díaz
,
Caitlin
Woolley
,
Andy
Brown
,
Loukas
Zampelis
,
Trevor
Mcardle
,
Molly
Worth
,
Timothy
Thornber
,
Ibrahim
Albariqi
,
Rachel C.
Kilbride
,
Tingxiang
Yang
,
C. Neil
Hunter
,
Graham J.
Leggett
,
George
Koutsourakis
,
James C.
Blakesley
,
Fernando A.
Castro
,
David
Beynon
,
Trystan M.
Watson
,
Dumitru
Sirbu
,
David G.
Lidzey
Diamond Proposal Number(s):
[32789]
Open Access
Abstract: We fabricate a type of back-contact perovskite solar cell based on 1.5 μm-width grooves that are embossed into a plastic film whose opposing “walls” are selectively coated with either n- or p-type contacts. A perovskite precursor solution is then deposited into the grooves, creating individual photovoltaic devices. Each groove device is series-connected to its neighbors, creating minimodules consisting of hundreds of connected grooves. Here, we report on the fabrication of groove-based devices using slot-die coating to deposit the perovskite precursor and explore the structure of the perovskite in the grooves using a range of microscopy and spectroscopy techniques. Significantly, our devices do not contain any expensive or scarce elements such as indium, indicating that this technology is both sustainable and low-cost. Furthermore, all coating processes explored here were performed using roll-to-roll processing techniques. Our technology is therefore completely scalable and is consistent with high-throughput, low-cost manufacturing.
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Feb 2025
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I12-JEEP: Joint Engineering, Environmental and Processing
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Diamond Proposal Number(s):
[29851]
Open Access
Abstract: Irregular Li heterostructure growth at the interphase between the solid electrolyte and anode reduces solid-state Li metal battery (SSLMB) performance, but the fundamental cause is still elusive. Measuring and imaging Li+ ion diffusion in operando inside an SSLMB using a commercially standard cell configuration are extremely challenging because the ultra-light Li element exhibits a minute signal-to-noise ratio using most x-ray-related characterization methods, and the weak x-ray signals of Li+ are buried by strong signals of other heavy transition metal elements in the cathode and battery enclosure. Here, we pioneer novel operando correlative imaging of coupling x-ray Compton scattering with computed tomography (XCS-CT), which is able to quantify the interplay between spatially resolved Li+ ion diffusion kinetics and Li0 metal structure growth at the interphases of both the anode and cathode sides inside a full-cell SSLMB using a solid polymer electrolyte (SPE) and commercially standard cell configuration during (dis)charging. We show a 61% increase in the efficiency of extracting Li+ ions from the cathode LiNi0.6Mn0.2Co0.2O2 to the anode during charging at 0.1 C compared with at 1 C due to restricted Li+ ion diffusion at the higher rate inside SSLMB. However, this led to the formation of a more irregular interfacial morphology, consisting not only of Li0 dendrites, but also sub-surface pore formation at the anode/SPE interphase. We find that surprisingly, the irregular Li0 structure initiation and growth are accelerated during the first Li stripping step, not the Li plating step, and the root cause is the onset imbalance of Li+ ion diffusion and redox reactions between the anode and cathode. These insights highlight the benefits of asymmetric charging and discharging rates as a promising solution to improving SSLMB performance with SPEs. The operando correlative XCS-CT imaging technique has the potential to study the relationship between active ion concentrations and buried morphological changes for a variety of battery chemistries.
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Feb 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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B07-C-Versatile Soft X-ray beamline: Ambient Pressure XPS and NEXAFS
B18-Core EXAFS
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Diamond Proposal Number(s):
[36863]
Open Access
Abstract: A series of CeO2 supports were treated in an N2 plasma before being impregnated with Ni precursors to evaluate the impact this has on the metal-support interface and catalytic performance. This impact was determined using a suite of characterization methods including X-ray diffraction (XRD), H2 temperature-programmed reduction (H2-TPR), ex situ and in situ X-ray absorption spectroscopy (XAS) and in situ Kerr-gated Raman. The combined and self-consistent results indicated that plasma treatment of CeO2 can lead to the generation of an increasing number of oxygen vacancies, and a loss of long-range order in samples treated for 1 h, realizing a highly defective CeOx film at the interface between the Ni metal nanoparticles and the bulk CeO2. However, this highly defective CeOx surface significantly enhances the Ni-CeOx interaction, resulting in a number of smaller Ni NPs in intimate contact with the support, leading to improved catalytic performance for CO2 methanation. In situ diffuse reflectance infrared Fourier transform spectroscopy (DRIFTS) revealed that the more defect-dense Ni−CeOx interface leads to the formation of more bidentate bridged carbonates (vs. bidentate chelate) and which are more readily consumed during reaction, suggesting the identification of an important parameter to effect low-temperature (< 300 °C) CH4 production.
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Jan 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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I09-Surface and Interface Structural Analysis
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Diamond Proposal Number(s):
[30759]
Open Access
Abstract: Metal-oxide coatings are a favoured strategy for mitigating surface degradation problems in state-of-the-art lithium-ion battery Ni-rich layered positive electrode materials. Despite their extensive use, a full, fundamental understanding of the role of coatings in reducing degradation and extending cycling lifetimes is currently lacking. In this work, the interactions between an atomic layer deposited (ALD) alumina coating on polycrystalline LiNi0.8Mn0.1Co0.1O2 (NMC811) and a carbonate-based battery electrolyte are studied. Solid-state nuclear magnetic resonance (ssNMR) heteronuclear experiments show that the Al2O3 coating transforms by reacting with electrolyte species present before and during electrochemical cycling, scavenging protic and acidic species. Density-functional theory calculations highlight the additional chemical effect of the coating in locally stabilising the structure of the NMC811, limiting oxidation of the oxygen atoms coordinated to both Al and Ni, thereby limiting the surface reconstruction process and improving the electrochemical performance. Improved NMC811 surface stability is confirmed by monitoring gaseous degradation species by online electrochemical mass-spectrometry and via X-ray spectroscopic analysis of the electrochemically aged samples to examine changes in Ni and O oxidation state and local structure. The combination of this experimental and theoretical analysis suggests that Al2O3 coatings have a dual role: as a protective barrier against attack from chemical species in the electrolyte, and as an artificial passivating layer hindering oxygen loss and surface phase transformations. This holistic approach, which provides a fundamental understanding of how the surface stability is improved by the coating, will aid the design of the state-of-the-art and future positive electrode materials.
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Jan 2025
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I07-Surface & interface diffraction
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Feray
Ünlü
,
Alejandra
Florez
,
Keely
Dodd-Clements
,
Lennart K.
Reb
,
Michael
Götte
,
Matthias
Grosch
,
Fengning
Yang
,
Senol
Öz
,
Florian
Mathies
,
Sanjay
Mathur
,
Daniel
Ramirez
,
Franklin
Jaramillo
,
Eva
Unger
Diamond Proposal Number(s):
[36427]
Open Access
Abstract: Halide perovskite solar cells are approaching commercialization, with solution processing emerging as a key method for large-scale production. This study introduces a significant advancement: using non-toxic solvents like water and alcohol in perovskite precursor inks facilitated by the protic ionic liquid methylammonium propionate (MAP). MAP effectively dissolves perovskite precursors such as lead acetate and methylammonium iodide, enabling the first stable water-based perovskite precursor ink suitable for one-step slot-die coating. This new ink formulation contrasts with conventional dimethylformamide (DMF) and dimethylsulfoxide (DMSO)-based inks, as evidenced by in-situ grazing incidence wide-angle X-ray scattering (GIWAXS), which revealed an intermediate-free liquid-to-solid transition. In-situ mass spectrometry also showed that organic molecules evaporate during annealing, resulting in a crystalline perovskite phase. Optimization of the solvent mixture to H2O/IPA/MAP enabled successful slot-die coating, yielding perovskite solar cells with an efficiency of up to 10%. This eco-friendly ink reduces toxicity and environmental impact compared to DMF-based inks, offering a longer shelf life and the possibility of using the ink in ambient conditions. This pioneering work represents the first report of a water-based green ink formulation for one-step thin film coating at room-temperature conditions by slot-die coating, highlighting its potential for sustainable commercial applications.
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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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I07-Surface & interface diffraction
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Matteo
Degani
,
Riccardo
Pallotta
,
Giovanni
Pica
,
Masoud
Karimipour
,
Alessandro
Mirabelli
,
Kyle
Frohna
,
Miguel
Anaya
,
Tianyu
Xu
,
Chang-Qi
Ma
,
Samuel D.
Stranks
,
Monica Lira
Cantù
,
Giulia
Grancini
Diamond Proposal Number(s):
[32266]
Open Access
Abstract: Interface engineering using self-assembled 2D perovskite interfaces is a consolidated route to efficient and durable perovskite solar cells. Whether the 2D perovskite forms a homogeneous conformal layer or is heterogeneously distributed on the surface, interface defects are passivated, leading to a general improvement in the device's open circuit voltage (VOC) and stability. Here, an innovative strategy is developed for manipulating the composition of the 2D/3D perovskite interface that results in the formation of a gradient halide distribution, which extends from the surface to the bulk. The use of a bromide-based 2D perovskite triggers a progressive Br/I exchange, affecting not only the surface but also the perovskite underneath. As a result, not only the device VOC improve, as expected, but also the photogenerated current is boosted, leading to a device efficiency of up to 24.4%. Such mixed halide gradient effectively passivates surface and bulk defects making the perovskite active layer more efficient and robust, as demonstrated by the superior device stability showing zero losses in performances upon 36 days (more than 800 h) test in outdoor conditions, those ones relevant for a marketable product.
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Dec 2024
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