Search Results

You searched for all publications:

with publication states 'Published (Approved)'

Search Again...

These results only include publications that have been reviewed and processed by Diamond Light Source. To also view papers that have not yet been processed click here.

You can use the folder icon under Actions to collate papers as required. You can then click on View Folder in the left-hand navigation to review and/or download your folder.

Exact matches
Related results

5 items found (0 items not approved), displaying all items.1

Instruments / Technical Area	Publication Details	Published
I09-Surface and Interface Structural Analysis I21-Resonant Inelastic X-ray Scattering (RIXS)	Oxygen-redox activity in non-lithium-excess tungsten-doped LiNiO2 cathode A. S. Menon , B. J. Johnston , S. G. Booth , L. Zhang , K. Kress , B. E. Murdock , G. Paez Fajardo , N. N. Anthonisamy , N. Tapia-Ruiz , S. Agrestini , M. Garcia-Fernandez , K. Zhou , P. K. Thakur , T. L. Lee , A. J. Nedoma , S. A. Cussen , L. F. J. Piper Prx Energy 2 DOI: 10.1103/PRXEnergy.2.013005 Diamond Proposal Number(s): [29104, 29113] Open Access Show Abstract ▼ Abstract: The desire to increase the energy density of stoichiometric layered Li TM O 2 (TM = 3d transition metal) cathode materials has promoted investigation into their properties at high states of charge. Although there is increasing evidence for pronounced oxygen participation in the charge compensation mechanism, questions remain whether this is true O -redox, as observed in Li -excess cathodes. Through a high-resolution O K-edge resonant inelastic x-ray spectroscopy (RIXS) study of the Mn -free Ni -rich layered oxide Li Ni 0.98 W 0.02 O 2 , we demonstrate that the same oxidized oxygen environment exists in both Li -excess and non- Li -excess systems. The observation of identical RIXS loss features in both classes of compounds is remarkable given the differences in their crystallographic structure and delithiation pathways. This lack of a specific structural motif reveals the importance of electron correlation in the charge compensation mechanism for these systems and indicates how a better description of charge compensation in layered oxides is required to understand anionic redox for energy storage.	Mar 2023
I11-High Resolution Powder Diffraction	Synthetic pathway determines the nonequilibrium crystallography of Li- and Mn-rich layered oxide cathode materials Ashok S. Menon , Seda Ulusoy , Dickson O. Ojwang , Lars Riekehr , Christophe Didier , Vanessa K. Peterson , German Salazar-Alvarez , Peter Svedlindh , Kristina Edström , Cesar Pay Gomez , William R. Brant Acs Applied Energy Materials DOI: 10.1021/acsaem.0c03027 Diamond Proposal Number(s): [21804] Open Access Show Abstract ▼ Abstract: Li- and Mn-rich layered oxides show significant promise as electrode materials for future Li-ion batteries. However, an accurate description of its crystallography remains elusive, with both single-phase solid solution and multiphase structures being proposed for high performing materials such as Li1.2Mn0.54Ni0.13Co0.13O2. Herein, we report the synthesis of single- and multiphase variants of this material through sol–gel and solid-state methods, respectively, and demonstrate that its crystallography is a direct consequence of the synthetic route and not necessarily an inherent property of the composition, as previously argued. This was accomplished via complementary techniques that probe the bulk and local structure followed by in situ methods to map the synthetic progression. As the electrochemical performance and anionic redox behavior are often rationalized on the basis of the presumed crystal structure, clarifying the structural ambiguities is an important step toward harnessing its potential as an electrode material.	Feb 2021
I09-Surface and Interface Structural Analysis	Understanding the roles of tris(trimethylsilyl) phosphite (TMSPi) in LiNi 0.8 Mn 0.1 Co 0.1 O 2 (NMC811)/silicon–graphite (Si–Gr) lithium‐ion batteries Haidong Liu , Andrew Naylor , Ashok Sreekumar Menon , William R. Brant , Kristina Edström , Reza Younesi Advanced Materials Interfaces 8 DOI: 10.1002/admi.202000277 Diamond Proposal Number(s): [23159] Open Access Show Abstract ▼ Abstract: The coupling of nickel‐rich LiNi0.8Mn0.1Co0.1O2 (NMC811) cathodes with high‐capacity silicon–graphite (Si–Gr) anodes is one promising route to further increase the energy density of lithium‐ion batteries. Practically, however, the cycle life of such cells is seriously hindered due to continuous electrolyte degradation on the surfaces of both electrodes. In this study, tris(trimethylsilyl) phosphite (TMSPi) is introduced as an electrolyte additive to improve the electrochemical performance of the NMC811/Si–Gr full cells through formation of protective surface layers at the electrode/electrolyte interfaces. This is thought to prevent the surface fluorination of the active materials and enhance interfacial stability. Notably, TMSPi is shown to significantly reduce the overpotential and operando X‐ray diffraction (XRD) confirms that an irreversible “two‐phase” transition reaction caused by the formed adventitious Li2CO3 layer on the surface of NMC811 can transfer to a solid‐solution reaction mechanism with TMSPi‐added electrolyte. Moreover, influences of TMSPi on the cathode electrolyte interphase (CEI) on the NMC811 and solid electrolyte interphase (SEI) on the Si–Gr are systematically investigated by electron microscopy and synchrotron‐based X‐ray photoelectron spectroscopy which allows for the nondestructive depth‐profiling analysis of chemical compositions and oxidation states close to the electrode surfaces.	Jun 2020
I11-High Resolution Powder Diffraction	The influence of synthesis routes on the crystallography, morphology and electrochemistry of Li2MnO3 Ashok Sreekumar Menon , Dickson O. Ojwang , Tom Willhammar , Vanessa K. Peterson , Kristina Edstrom , Cesar Pay Gòmez , William R. Brant Acs Applied Materials & Interfaces DOI: 10.1021/acsami.9b20754 Diamond Proposal Number(s): [19093] Show Abstract ▼ Abstract: With the potential of delivering reversible capacities of up to 300 mAh/g, Li-rich transition metal oxides hold great promise as cathode materials for future Li-ion batteries. However, a cohesive synthesis-structure-electrochemistry relationship is still lacking for these materials, which impedes progress in the field. This work investigates how and why different synthesis routes, specifically solid-state and modified Pechini sol-gel methods, affect the properties of Li2MnO3, a compositionally simple member of this material system. Through a comprehensive investigation of the syn-thesis mechanism along with crystallographic, morphological and electrochemical characterization, the effects of different synthesis routes were found to predominantly influence the degree of stacking faults and particle morphology. That is, the modified Pechini method produced isotropic spherical particles with approx. 57% faulting and the solid state samples possessed heterogeneous morphology with approx. 43% faulting probability. Inevitably, these differences lead to variations in electrochemical performance. This study accentuates the importance of understanding how syn-thesis affects the electrochemistry of these materials, which is critical considering the crystallographic and electrochemical complexities of the class of materials more generally. The methodology employed here is extendable to studying synthesis-property relationships of other compositionally complex Li-rich layered oxide systems.	Jan 2020
I09-Surface and Interface Structural Analysis	Depth-dependent oxygen redox activity in lithium-rich layered oxide cathodes Andrew J. Naylor , Eszter Makkos , Julia Maibach , Niccolo Guerrini , Adam Sobkowiak , Erik Bjorklund , Juan G. Lozano , Ashok Sreekumar Menon , Reza Younesi , Matthew R. Roberts , Kristina Edström , M. Saiful Islam , Peter G. Bruce Journal Of Materials Chemistry A DOI: 10.1039/C9TA09019C Diamond Proposal Number(s): [14733, 16629] Open Access Show Abstract ▼ Abstract: Lithium-rich materials, such as Li1.2Ni0.2Mn0.6O2, exhibit capacities not limited by transition metal redox, through the reversible oxidation of oxide anions. Here we offer detailed insight into the degree of oxygen redox as a function of depth within the material as it is charged and cycled. Energy-tuned photoelectron spectroscopy is used as a powerful, yet highly sensitive technique to probe electronic states of oxygen and transition metals from the top few nanometers at the near-surface through to the bulk of the particles. Two discrete oxygen species are identified, On- and O2-, where n<2, confirming our previous model that oxidation generates localised hole states on O upon charging. This is in contrast to the oxygen redox inactive high voltage spinel LiNi0.5Mn1.5O4, for which no On- species is detected. The depth profile results demonstrate a concentration gradient exists for On- from the surface through to the bulk, indicating a preferential surface oxidation of the layered oxide particles. This is highly consistent with the already well-established core-shell model for such materials. Ab initio calculations reaffirm the electronic structure differences observed experimentally between the surface and bulk, while modelling of delithiated structures shows good agreement between experimental and calculated binding energies for On-.	Sep 2019

Publications Database

Search Results

You searched for all publications:

Search Again...

Subject Areas (check all that apply) select all

Instruments used to collect data (check all that apply) select all

Collaborations involved (check all that apply) select all

Diamond Offline Facilities used

Relevant Technical Areas (check all that apply) select all

Menu for Anonymous User