I18-Microfocus Spectroscopy
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Diamond Proposal Number(s):
[33166]
Open Access
Abstract: Operating lithium ion batteries (LIBs) to high charging cut off potentials allows us to accommodate a further push in energy density. However, it requires a thorough understanding of the interplay and temperature dependence of parasitic reactions that aggravate the aging of the electrolyte and the cathode/anode electrodes. In the present study we investigated the interplay of the chemical and the electrochemical electrolyte oxidation, how they are related to the dissolution of transition metal (TM) ions from the cathode active material (CAM), and how they shift or accelerate with temperature. Through an optimized electrochemical protocol an excellent potential dependence of the gas evolution of a LiNi0.80Co0.15Al0.05O2 (NCA) charged against a free standing graphite on a lithium metal electrode in a LP47 electrolyte was achieved. We identified O2 and PF5 gas as suitable proxies for the chemical and electrochemical electrolyte oxidation, respectively. Both processes are separated by at least 300 mV over a temperature range from 10 to 45°C. Through temperature-dependent operando hard X ray absorption spectroscopy measurements and their comparison with the gassing results, it will be shown, that the electrochemical oxidation of the electrolyte is directly linked to the dissolution of TMs, while the chemical electrolyte oxidation mainly leaves the transition metal dissolution unaffected.
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Jun 2025
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I11-High Resolution Powder Diffraction
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Abstract: This thesis contains work related to the sustainable development of an aqueous aluminum ion battery. The battery consists of a titanium dioxide negative electrode and copper hexacynoferrate positive electrode, the electrolyte is 1 M aluminium chloride and 1 M potassium chloride. At the start of the PhD project the reported energy density was 15 Wh kg
−
1
and power density of 300 W kg
−
1
, with a cycle life of 1750 charge/discharge cycles.
Aluminium is a viable option for secondary battery technology, not only is the theoretical energy density high (~8000 W kg
−
1
), but there are already well established mining, production, and recycling industries built around aluminium, making it a sustainable option too. Further, the use of an aqueous electrolyte, while limiting of the voltage range a cell can operate at - due to the electrochemical stability window of water - is an inherently safe option for an electrolyte, which also boasts an ease of manufacture.
The core concept throughout this thesis is that of minimising the environmental impacts of the battery as the design develops, and as such, a life-cycle assessment (LCA) is conducted on the current stage of the design, and compared to supercapacitors - this is due to the pseudo-capacitive, high power, nature of the battery. The design, in its current bench-based state, is found to be more environmentally friendly overall than commercial supercapacitors, and capacitors. A practical application of this battery in a dual energy storage system is studied for an EV car and bus, showing that, for a long lifetime of the EV, using dual energy storage systems has reduced environmental impacts. The LCA results were then compared to the market leader in energy storage (Li-ion) for environmental impacts.
Based on the comparison to Li-ion, development goals were set based on achieving the same or better lifetime CO
2
emissions, and it was found that by increasing the cycle life of the battery, and increasing the amount of utilised active material within the battery, it would become environmentally competitive with Li-ion. Following this outcome, the focus for the experimental part of the PhD was split into active material increase and lifetime extension.
To increase the active material \% within the battery, both increasing the actual amount of active material, and reducing the amount of support material were investigated. Coin-cell development of this battery to reduce support material found that a closed cell would not be appropriate - due to gas production, however 7000 stable cycles were achieved with an uncrimped cell. The loading of active material within the battery was investigated and found that a lower loading lead to increased discharge capacity (287.2 mAh g
−
1
for the positive and 205 mAh g
−
1
for the negative electrode). The performance of the TiO
2
electrodes were also investigated in terms of temperature. Given the porosity of the carbon felt, the impacts of compression on performance is being investigated in collaboration with Diamond Light Source, and initial findings are presented.
For increasing the lifetime of a battery it is prudent to understand the degradation mechanisms that occur over time as the battery loses capacity. Once this is known, design decisions and usage prescriptions can be made to mitigate or minimise these mechanisms and therefore increase the life of the battery. Based on this, a long duration experiment spanning eleven months was run at Diamond Light Source, which performed X-ray diffraction on six cycling coin cells each week. The resulting diffraction patterns, alongside X-ray computed tomography of the final coin cells have uncovered information about how the make up of the electrodes have changed over time.
Overall, this thesis shows that by working with the environmental impacts of a battery, we can produce development road-maps that both improve performance and respects the planet.
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Jun 2025
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I09-Surface and Interface Structural Analysis
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Bhavya
Rakheja
,
Adam
Hultqvist
,
Rahul Mahavir
Varma
,
Natalia M.
Martin
,
Karen
Radetzky
,
Stefania
Riva
,
Evelyn
Johannesson
,
Ute B.
Cappel
,
Hakan
Rensmo
,
Erik M. J.
Johansson
,
Tobias
Torndahl
Diamond Proposal Number(s):
[35209]
Open Access
Abstract: Tin oxide (SnOx) by atomic-layer deposition (ALD), in combination with fullerene, is widely employed as an electron transport layer in p–i–n perovskite solar cells. This study investigates the direct deposition of ALD SnOx on top of formamidinium (FA)-based perovskites, as a step toward the elimination of the fullerene interlayer and its poor effect on solar cell’s long-term stability. The interfacial chemistry between FA-based perovskites (FAPbI3 and FAPbBr3) and ALD SnOx was studied using soft and hard X-ray photoelectron spectroscopy (SOXPES and HAXPES) with a focus on investigating the separate roles FA and different halides play during interface formation. FAPbI3 and FAPbBr3 solar cell structures solely containing ALD SnOx resulted in s-shaped current–voltage characteristics, indicating the formation of a transport barrier at the interface. Both SOXPES and HAXPES measurements revealed the emergence of additional nitrogen states at the interface during the ALD SnOx deposition on FAPbI3 and FAPbBr3, where these states are linked to the decomposition of FA+. The FAPbI3/ALD SnOx interface also showed the presence of lead iodide (PbI2) through additional lead states other than that from FAPbI3 by using SOXPES measurements. Concerning the FAPbBr3/ALD SnOx interface, no additional lead states were observed; however, measurements instead revealed the formation of Sn–Br bonds at the interface along with the migration of bromine ions into the bulk of the ALD SnOx. Thus, FAPbI3 and FAPbBr3 undergo distinct reaction pathways upon direct deposition of ALD SnOx on top of them. We reason that the decomposition of FA+ in both perovskites and the formation of PbI2 at the FAPbI3/ALD SnOx interface and the incorporation of Br in SnOx at the FAPbBr3/ALD SnOx interface prove detrimental toward device performance. Therefore, careful interfacial engineering that can mitigate the formation of these products should be utilized to enhance the performance of perovskite solar cells.
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Jun 2025
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I19-Small Molecule Single Crystal Diffraction
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Milos
Dubajic
,
James R.
Neilson
,
Johan
Klarbring
,
Xia
Liang
,
Stephanie A.
Bird
,
Kirrily C.
Rule
,
Josie E.
Auckett
,
Thomas A.
Selby
,
Ganbaatar
Tumen-Ulzii
,
Yang
Lu
,
Young-Kwang
Jung
,
Cullen
Chosy
,
Zimu
Wei
,
Yorrick
Boeije
,
Martin V.
Zimmermann
,
Andreas
Pusch
,
Leilei
Gu
,
Xuguang
Jia
,
Qiyuan
Wu
,
Julia C.
Trowbridge
,
Eve M.
Mozur
,
Arianna
Minelli
,
Nikolaj
Roth
,
Kieran W. P.
Orr
,
Arman
Mahboubi Soufiani
,
Simon
Kahmann
,
Irina
Kabakova
,
Jianning
Ding
,
Tom
Wu
,
Gavin J.
Conibeer
,
Stephen P.
Bremner
,
Michael P.
Nielsen
,
Aron
Walsh
,
Samuel D.
Stranks
Diamond Proposal Number(s):
[33123]
Open Access
Abstract: Lead halide perovskites have emerged as promising materials for solar energy conversion and X-ray detection owing to their remarkable optoelectronic properties. However, the microscopic origins of their superior performance remain unclear. Here we show that low-symmetry dynamic nanodomains present in the high-symmetry average cubic phases, whose characteristics are dictated by the A-site cation, govern the macroscopic behaviour. We combine X-ray diffuse scattering, inelastic neutron spectroscopy, hyperspectral photoluminescence microscopy and machine-learning-assisted molecular dynamics simulations to directly correlate local nanoscale dynamics with macroscopic optoelectronic response. Our approach reveals that methylammonium-based perovskites form densely packed, anisotropic dynamic nanodomains with out-of-phase octahedral tilting, whereas formamidinium-based systems develop sparse, isotropic, spherical nanodomains with in-phase tilting, even when crystallography reveals cubic symmetry on average. We demonstrate that these sparsely distributed isotropic nanodomains present in formamidinium-based systems reduce electronic dynamic disorder, resulting in a beneficial optoelectronic response, thereby enhancing the performance of formamidinium-based lead halide perovskite devices. By elucidating the influence of the A-site cation on local dynamic nanodomains, and consequently, on the macroscopic properties, we propose leveraging this relationship to engineer the optoelectronic response of these materials, propelling further advancements in perovskite-based photovoltaics, optoelectronics and X-ray imaging.
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Jun 2025
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I09-Surface and Interface Structural Analysis
I11-High Resolution Powder Diffraction
|
Tao
Zeng
,
Ziqin
Jiao
,
Xiaoyu
Gao
,
Maolin
Yang
,
Xiaohu
Wang
,
Wenguang
Zhao
,
Wei
Tang
,
Mihai
Chu
,
Ze
He
,
Jinqi
Li
,
Zhongyuan
Huang
,
Guojie
Chen
,
Ziwei
Chen
,
Rui
Wang
,
Liming
Wang
,
Junrong
Zhang
,
Lunhua
He
,
Yuguang
Pu
,
Yinguo
Xiao
Diamond Proposal Number(s):
[36187, 34243]
Abstract: Li-rich manganese-based oxides (LRMO) are promising cathode materials for next-generation lithium-ion batteries due to their high-capacity and low-cost merits. However, the low initial coulombic efficiency (ICE) and irreversible oxygen release of LRMO severely hinder their commercialization processes. Here, we employ glyoxal treatment to modulate the hybridization between transition metal (TM) 3d and oxygen (O) 2p orbitals in LRMO. This approach is found to reduce the Co/Mn t2g-O 2p hybridization in LRMO while simultaneously activating the Co2+/Co3+ redox below the Fermi level. Our findings demonstrate that tuning TM 3d-O 2p orbital hybridization can be a viable approach to improve the ICE of LMRO. Specifically, the ICE of LRMO can be elevated from 85.3 % to 102.5 %, and a high specific capacity of 291.2 mAh g−1 can be achieved at 0.1 C. Moreover, the treated LRMO cathodes exhibit significantly enhanced capacity retention.
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May 2025
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I11-High Resolution Powder Diffraction
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Diamond Proposal Number(s):
[36397]
Abstract: Niobium–based Wadsley–Roth oxides have recently attracted attention as promising anode materials for lithium-ion batteries, providing high charging and discharging rates and cycling stability. The higher operating potential of Wadsley–Roth oxide anodes, while impacting the overall energy density, reduces the risk of dendrite formation, making them safer at high power densities. We present the rapid preparation of two Wadsley–Roth oxide compounds, AlNb11O29 and Ti2Nb10O29, by a microwave-assisted preparation method in under 10 min starting from oxide materials, and heating in open crucibles. No further processing is required to make effective electrode materials from these compounds other than grinding with the usual conducting carbon and binder. High-resolution synchrotron X-ray diffraction and scanning electron microscopy are employed to understand the impact of rapid preparation on the structure and morphology. Excellent electrochemical performance is achieved, with reversible capacities of up to 250 mAh g–1 with high capacity retention over 100 cycles and fast-charging rates up to 10C without much loss of capacity. The materials reported here are compared to reports from the literature. Despite the very similar structures and compositions, AlNb11O29 is found to be less effective as an anode material than Ti2Nb10O29, and in this work, we delve into possible reasons for this.
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May 2025
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I11-High Resolution Powder Diffraction
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Diamond Proposal Number(s):
[28349]
Open Access
Abstract: An understanding of the nature of the grain boundaries and impurity phases contained in complex mixed metal oxide solid electrolytes is key to the development of improved and more stable solid-state batteries with reduced grain boundary resistances and higher ionic conductivities of the bulk sample. The Li-ion solid electrolyte Li7La3Zr2O12 (LLZO) is one of the most researched electrolytes in the field due to its high ionic conductivity, thermal stability, and wide voltage stability window. Despite its potential, the nature of the impurity and surface phases formed during the synthesis of LLZO and their role and influence on LLZO’s performance when used as an electrolyte remain poorly understood and controlled. In addition, there are limited characterization methods available for detailed studies of these impurity phases, particularly if these phases are buried in or close to the grain boundaries of a dense sintered material. Here, we demonstrate a solid-state nuclear magnetic resonance (ssNMR) and dynamic nuclear polarization (DNP) approach that exploits both endogenous and exogenous dopants to select for either specific impurities or separate bulk vs surface/subsurface phases. Specifically, the location of Al-containing phases within an Al doped LLZO and the impurity phases that form during synthesis are mapped: by doping LLZO with trace amounts of paramagnetic metal ions (Fe3+ and Gd3+), DNP is used to selectively probe Al- and La-containing impurity phases, respectively, allowing us to enhance the signals arising from the LiAlO2 and LaAlO3 impurities and to confirm their identity. A 17O DNP experiment using Gd3+ doped LLZO is performed to identify further La3+-containing impurities (specifically La2Zr2O7 and La2O3). Finally, a 7Li DNP irradiated 7Li–27Al dipolar-based heteronuclear multiple quantum correlation experiment is performed by using the radical TEKPol as the polarization agent. This experiment demonstrates that the poorly crystalline LiAlO2 that is found close to the surfaces of the LLZO composite is coated by a thin Li-containing impurity layer and thus not directly present at the surface.
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May 2025
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I09-Surface and Interface Structural Analysis
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Qianhui
Liu
,
Tove
Ericson
,
Robert
Temperton
,
Ida
Kallquist
,
Fredrik
Lindgren
,
Laura
King
,
Alenka
Križan
,
Katie L.
Browning
,
Ethan
Crumlin
,
Gabriel M.
Veith
,
Maria
Hahlin
Diamond Proposal Number(s):
[36581]
Open Access
Abstract: The real-time interface chemistry between the lithium cobalt oxide (LCO) working electrode and the LiClO4/propylene carbonate (PC) electrolyte is investigated during lithiation/delithiation using dip-and-pull ambient pressure photoelectron spectroscopy (APXPS). The APXPS results appear to exhibit the seldom discussed Co2+ state in the LCO structure, where the operando measurements indicate electron transfer among Co2+, Co3+, and Co4+ states. Specifically, the lithiation of LCO reduces the Co4+ state to both Co3+ and Co2+ states, where, as a function of voltage, reduction to Co2+ state is initially more pronounced followed by Co3+ formation. In addition, a delay in surface delithiation is observed during the reverse potential steps. This is discussed in terms of overpotential at the interface measurement position as a consequence of the dip-and-pull setup for this experiment. Finally, the shifts in the apparent binding energies of the spectral features corresponding to the electrolyte and LCO at their interface shows that the electrochemical potentials at delithiation voltage steps are different from the lithiation steps at the same applied voltages. This further explains the non-responsive delithiation. The BE shift observed from the LCO surface is argued to be dominantly due to the semi-conductive nature of the sample. Overall, this article shows the importance of operando APXPS for probing non-equilibrium states in battery electrodes for understanding electron transfer in the reactions.
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May 2025
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I11-High Resolution Powder Diffraction
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Diamond Proposal Number(s):
[36397]
Abstract: Li-rich cathodes with an O2-type layer stacking offer high gravimetric capacities and fast charge–discharge rates, and are structurally more stable with respect to transition metal migration than O3-type Li-rich cathodes. However, the nature and reversibility of their charge–discharge processes remain poorly understood, in part because these materials can only be obtained through soft chemistry routes. This work provides a new structural model for a recently-reported O2-type cathode with nominal composition Li1.1Al0.04Mn0.65Ni0.21O2 and excellent structural and potential stability. Our new model hints at the impact of short-range cation ordering and phase separation on the electrochemical performance. Neutron and X-ray diffraction indicate that the as-synthesized compound comprises two crystallographically distinct phases—a Li2MnO3 component and a Li-poor (Li0.78Al0.02Mn0.67Ni0.31O2) component—most likely stacked epitaxially along the c-axis. 7Li, 17O and 27Al solid-state NMR measurements further reveal a tendency towards honeycomb ordering on the transition metal sublattice—long-range ordering in Li2MnO3 and partial, short-range ordering in Li0.78Al0.02Mn0.67Ni0.31O2—and highlight the presence of dilithium environments within the transition metal layer in Li2MnO3, with important consequences on structural stability during electrochemical cycling.
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May 2025
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I13-2-Diamond Manchester Imaging
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Diamond Proposal Number(s):
[22198]
Open Access
Abstract: Solid-state lithium batteries are developing rapidly as a promising next-generation battery, while challenges still persist in understanding their degradation processes during cycling due to the difficulties in characterization. In this study, the 3D morphological evolution of the Li3PS4 solid electrolyte was tracked during electrochemical cycles (plating and stripping) until short circuit by utilizing in situ synchrotron X-ray computed tomography with sufficient spatial and temporal resolution. During the degradation process, cracks in the electrolyte alternately generated from the two electrode/electrolyte interfaces and propagated until shorting. The lithium dendrites filled in the electrolyte cracks but had a greatly reduced filling ratio after the first plating stage; therefore, the cell could continue working for some time after the solid electrolyte was fully fractured by cracks. The compression of the two lithium electrodes mainly occurred in initial cycles where a ca. 4–7 μm reduction in thickness was observed. The mechanical force and electric potential fields were modeled to visualize their redistributions in different stages of cycling. The release of strain energy after the first penetration and thereafter the subsequent driving forces are discussed. These results reveal a fast degradation of solid electrolyte in the initial cycles, providing insights for further modifications and improvements in solid-state batteries.
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May 2025
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