I15-1-X-ray Pair Distribution Function (XPDF)
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Zixuan
Li
,
Rui
Qi
,
Yi
Yuan
,
Lechen
Yang
,
Lijiang
Song
,
Ashok S.
Menon
,
Louis F. J.
Piper
,
Didier
Wermeille
,
Paul
Thompson
,
Robert A.
House
,
Peter G.
Bruce
,
Alex W.
Robertson
Open Access
Abstract: Aqueous zinc-ion batteries (ZIBs) suffer from sustained capacity loss at the zinc metal anode due to side reactions with the electrolyte, even under idle conditions. The concept of an anode-free ZIB would address this degradation by eliminating the metal anode source. A key requirement for such systems is a cathode that contains zinc in its pristine state and supports initial charging. Here, we report the synthesis and characterization of cation-disordered rocksalt (DRX) ZnMnO2, a new cathode material suitable for anode-free ZIBs. ZnMnO2 meets the essential criteria for anode-free operation of natively containing Zn in the pristine state, enabling an initial charge, as well as offering high initial charge capacity (312.8 mAh g−1), and discharge voltage (1.36 V). We show that the dominant energy storage mechanism involves Mn dissolution and redeposition, with a smaller contribution arising from reversible Zn intercalation into a spinel phase that forms in situ during cycling. We further demonstrate the versatility of DRX cathodes by extending the concept to ZnFeO2. These findings establish DRX materials as a promising platform for the development of cathodes suitable for anode-free ZIBs.
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Oct 2025
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I13-2-Diamond Manchester Imaging
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Dominic L. R.
Melvin
,
Marco
Siniscalchi
,
Dominic
Spencer-Jolly
,
Bingkun
Hu
,
Ziyang
Ning
,
Shengming
Zhang
,
Junfu
Bu
,
Shashidhara
Marathe
,
Anne
Bonnin
,
Johannes
Ihli
,
Gregory J.
Rees
,
Patrick S.
Grant
,
Charles W.
Monroe
,
T. James
Marrow
,
Guanchen
Li
,
Peter G.
Bruce
Diamond Proposal Number(s):
[30683]
Open Access
Abstract: Avoiding lithium dendrites at the lithium/ceramic electrolyte interface and, as a result, avoiding cell short circuit when plating at practical current densities remains a significant challenge for all-solid-state batteries. Typically, values are limited to around 1 mA cm−2, even, for example, for garnets with a relative density of >99%. It is not obvious that simply densifying ceramic electrolytes will deliver high plating currents. Here we show that plating currents of 9 mA cm−2 can be achieved without dendrite formation, by densifying argyrodite, Li6PS5Cl, to 99%. Changes in the microstructure of Li6PS5Cl on densification from 83 to 99% were determined by focused ion beam-scanning electron microscopy tomography and used to calculate their effect on the critical current density (CCD). Modelling shows that not all changes in microstructure with densification act to increase CCD. Whereas smaller pores and shorter cracks increase CCD, lower pore population and narrower cracks act to decrease CCD. Calculations show that the former changes dominate over the latter, predicating an overall increase in CCD, as observed experimentally.
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Sep 2025
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I15-1-X-ray Pair Distribution Function (XPDF)
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Bartholomew T.
Payne
,
Mikkel
Juelsholt
,
Miguel A.
Pérez-Osorio
,
Dominic L. R.
Melvin
,
Gabriel J.
Cuello
,
Emmanuelle
Suard
,
Daniel J. M.
Irving
,
Nicholas
Rees
,
Mark
Feaviour
,
Enrico
Petrucco
,
Stephen
Day
,
Gregory J.
Rees
,
Peter G.
Bruce
Open Access
Abstract: The rate performance of all-solid-state batteries can be limited by the low conductivity of the solid electrolyte in the composite cathode. A conductivity of 10 mS cm⁻¹ is required, which exceeds that of many solid electrolytes. This limitation can be attributed to intra- and inter-grain ion transport. Understanding the limitations of ion transport is a multi-length scale problem ranging from single bond hops to particle-particle transport. Here we show that spark plasma sintering of Li6PS5Cl not only enhances ion transport on the macroscopic length scale but also on the microscopic scale. On the macroscopic length scale, greater densification improves particle-to- particle contact. On the nanoscale, short-range order (SRO) of the neighbouring 4a/4a and 4d/4d Wyckoff sites present in the cold-pressed Li6PS5Cl produces unfavourable Li ion pathways through the cell. Spark plasma heating removes the SRO, creating a connected network of microscopic pathways for the Li to migrate. Finally, on the atomistic level, spark plasma heating increases the amount of Cl− residing on the 4d site and S2− on the 4a site. By understanding the limitations of ion mobility across a range of length scales, one can target methods to produce solid-state argyrodite electrolytes with higher ionic conductivities.
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Aug 2025
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I15-1-X-ray Pair Distribution Function (XPDF)
I21-Resonant Inelastic X-ray Scattering (RIXS)
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Diamond Proposal Number(s):
[35064, 39285, 40912]
Open Access
Abstract: Li-rich disordered rocksalts are promising next-generation cathode materials for Li-ion batteries. Recent reports have shown it is also possible to obtain Na-rich disordered rocksalts, however, it is currently poorly understood how the knowledge of the structural and redox chemistry translates from the Li-rich to the Na-rich analogs. Here, the properties of Li2MnO2F and Na2MnO2F are compared, which have different ion sizes (Li+ = 0.76 vs Na+ = 1.02 Å) but the same disordered rocksalt structure and stoichiometry. It is found that Na2MnO2F exhibits lower voltage Mn- and O-redox couples, opening access to a wider compositional range within the same voltage limits. Furthermore, the intercalation mechanism switches from predominantly single-phase solid solution behavior in Li2MnO2F to a two-phase transition in Na2MnO2F, accompanied by a greater decrease in the average Mn─O/F bond length. Li2MnO2F retains its long-range disordered rocksalt structure throughout the first cycle. In contrast, Na2MnO2F becomes completely amorphous during charge and develops a local structure characteristic of a post-spinel. This amorphization is partially reversible on discharge. The results show how the ion intercalation behavior of disordered rocksalts differs dramatically when changing from Li- to Na-ions and offers routes to control the electrochemical properties of these high-energy-density cathodes.
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May 2025
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I09-Surface and Interface Structural Analysis
I15-1-X-ray Pair Distribution Function (XPDF)
I21-Resonant Inelastic X-ray Scattering (RIXS)
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Liquan
Pi
,
Erik
Bjorklund
,
Gregory J.
Rees
,
Weixin
Song
,
Chen
Gong
,
John-Joseph
Marie
,
Xiangwen
Gao
,
Shengda D.
Pu
,
Mikkel
Juelsholt
,
Philip A.
Chater
,
Joohyuk
Park
,
Min Gyu
Kim
,
Jaewon
Choi
,
Stefano
Agrestini
,
Mirian
Garcia-Fernandez
,
Ke-Jin
Zhou
,
Alex W.
Robertson
,
Robert S.
Weatherup
,
Robert A.
House
,
Peter G.
Bruce
Diamond Proposal Number(s):
[27336, 29028, 25807]
Abstract: Disordered rocksalt cathodes deliver high energy densities, but they suffer from pronounced capacity and voltage fade on cycling. Here, we investigate fade using two disordered rocksalt lithium manganese oxyfluorides: Li3Mn2O3F2 (Li1.2Mn0.8O1.2F0.8), which stores charge by Mn2+/Mn4+ redox, and Li2MnO2F, where charge storage involves both Mn3+/Mn4+ and oxygen redox (O-redox). Li3Mn2O3F2 is reported for the first time. We identify the growth of an electronically resistive surface layer with cycling that is present in both Li2MnO2F and Li3Mn2O3F2 but more pronounced in the presence of O-redox. This resistive surface inhibits electronic contact between particles, leading to the observed voltage polarization and capacity loss. By increasing carbon loading in the composite cathode, it is possible to substantially improve the cycling performance. These results help to disentangle O-redox from other leading causes of capacity fading in Mn oxyfluorides and highlight the importance of maintaining electronic conductivity in improving capacity and voltage retention.
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Dec 2024
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E01-JEM ARM 200CF
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Diamond Proposal Number(s):
[32135]
Open Access
Abstract: Understanding Li+ ion diffusion pathways in Li-rich layered transition metal (TM) oxides is crucial for understanding the sluggish kinetics in anionic O2– redox. Although Li diffusion within the alkali layers undergoes a low-barrier octahedral–tetrahedral–octahedral pathway, it is less clear how Li diffuses in and out of the TM layers, particularly given the complex structural rearrangements that take place during the oxidation of O2–. Here, we develop simultaneous electron ptychography and annular dark field imaging methods to unlock the Li migration pathways in Li1.2Ni0.13Mn0.54Co0.13O2 associated with structural changes in the charge–discharge cycle. At the end of TM oxidation and before the high-voltage O oxidation plateau, we show that the Li migrating out of the TM layers occupies the alkali-layer tetrahedral sites on opposite sides of the TM layers, forming Li–Li dumbbell configurations, consistent with the density functional theory calculations. Also occurring are the TM migration and phase transition from O3 to O1 stacking, leading to unstable tetrahedral Li and the absence of Li contrast in imaging. Upon further Li deintercalation to 4.8 V, most of the tetrahedral Li are removed. After discharging to 2 V, we did not identify the reformation of tetrahedral Li but observed permanently migrated TMs at the alkali-layer sites, disfavoring the Li occupying the tetrahedral sites for diffusion. Our findings suggest a landscape of Li diffusion pathways in Li-rich layered oxides and strategies for minimizing the disruption of Li diffusion.
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Aug 2024
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I15-1-X-ray Pair Distribution Function (XPDF)
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Robert A.
House
,
Yuan
Quan
,
Dingqiao
Ji
,
Yi
Yuan
,
Hang
Xu
,
Rui
Qi
,
Sofia
De Sousa Coutinho
,
Sibylle
Riedel
,
Zhirong
Zhao-Karger
,
Lijiang
Song
,
Alex W
Robertson
,
Peter G.
Bruce
Diamond Proposal Number(s):
[35103]
Open Access
Abstract: The discovery of new transition metal (TM) oxide cathodes which can act as intercalation hosts for Mg2+ ions is critical for the development of high energy density Mg-ion batteries. In Li-ion batteries, disordered rocksalts with sufficiently high Li+ charge carrier ion concentration, i.e. Li:TM >1.1, can support fast Li+ diffusion and therefore deliver high capacities (~300 mAh g-1) and rate performance. Here, we investigate a range of simple Mg-rich disordered rocksalt cathodes, Mg2TMO3 (TM = Mn, Ni, Co), which possess similar charge carrier ion concentrations and similar ratios between ion size and interstitial tetrahedron height to the Li-rich disordered rocksalts. We show that, even with high carbon loadings, elevated cycling temperatures and reduced particle and crystallite size, it is not possible to extract Mg2+, indicating Mg2+ transport through Mg-rich cathodes is far less facile than Li+ in the Li-rich counterparts. Despite this, we demonstrate that Li-rich disordered rocksalts, such as Li2-xMnO2F (x = 1), can act as intercalation hosts for Mg2+, opening possible routes to activating these Mg-rich systems.
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Aug 2024
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I12-JEEP: Joint Engineering, Environmental and Processing
I13-2-Diamond Manchester Imaging
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Bingkun
Hu
,
Shengming
Zhang
,
Ziyang
Ning
,
Dominic
Spencer-Jolly
,
Dominic L. R.
Melvin
,
Xiangwen
Gao
,
Johann
Perera
,
Shengda D.
Pu
,
Gregory J.
Rees
,
Longlong
Wang
,
Lechen
Yang
,
Hui
Gao
,
Shashidhara
Marathe
,
Genoveva
Burca
,
T. James
Marrow
,
Peter G.
Bruce
Diamond Proposal Number(s):
[26060, 30683, 28773]
Open Access
Abstract: Charging current densities of solid-state batteries with lithium metal anodes and ceramic electrolytes are severely limited due to lithium dendrites that penetrate the electrolyte leading to a short circuit. We show that dendrite growth can be inhibited by different crack deflection mechanisms when multi-layered solid electrolytes, such as Li6PS5Cl/Li3ScCl6/Li6PS5Cl and Li6PS5Cl/Li10GeP2S12/Li6PS5Cl, are employed but not when the inner layer is Li3PS4. X-ray tomographic imaging shows crack deflection along mechanically weak interfaces between solid electrolytes as a result of local mismatches in elastic moduli. Cracks are also deflected laterally within Li3ScCl6, which contains preferentially oriented particles. Deflection occurs without lithium being present. In cases where the inner layers react with lithium, the resulting decomposition products can fill and block crack propagation. All three mechanisms are effective at low stack pressures. Operating at 2.5 MPa, multi-layered solid electrolytes Li6PS5Cl/Li3ScCl6/Li6PS5Cl and Li6PS5Cl/Li10GeP2S12/Li6PS5Cl can achieve lithium plating at current densities exceeding 15 mA cm−2.
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Jul 2024
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B18-Core EXAFS
I21-Resonant Inelastic X-ray Scattering (RIXS)
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John-Joseph
Marie
,
Max
Jenkins
,
Jun
Chen
,
Gregory
Rees
,
Veronica
Celorrio
,
Jaewon
Choi
,
Stefano
Agrestini
,
Mirian
Garcia-Fernandez
,
Ke-Jin
Zhou
,
Robert A.
House
,
Peter G.
Bruce
Diamond Proposal Number(s):
[25785]
Open Access
Abstract: Achieving reversible O-redox through the formation of electron–holes on O could hold the key to a new generation of high energy density Na-ion cathodes. However, to date, it has only been demonstrated in a small handful of cathode materials and none of these materials exploit the dual benefit of high voltage transition metal redox and O-redox, instead relying on Mn3+/4+ capacity close to 2 V vs Na+/Na. Here, a new Na-ion cathode exhibiting electron–holes on O is demonstrated, P2-type Na0.67Li0.1Ni0.3Mn0.6O2, which also utilizes the high voltage Ni3+/4+ redox couple to deliver the highest reported energy density among this class of compound. By employing a low Li content and avoiding honeycomb ordering within the transition metal layer, it is possible to stabilize the hole states, and the high voltage plateau is preserved in Na0.67Li0.1Ni0.3Mn0.6O2 over cycling.
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Jul 2024
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I15-1-X-ray Pair Distribution Function (XPDF)
I21-Resonant Inelastic X-ray Scattering (RIXS)
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Mikkel
Juelsholt
,
Jun
Chen
,
Miguel A.
Pérez-Osorio
,
Gregory
Rees
,
Sofia
De Sousa Coutinho
,
Helen E.
Maynard-Casely
,
Jue
Liu
,
Michelle
Everett
,
Stefano
Agrestini
,
Mirian
Garcia-Fernandez
,
Ke-Jin
Zhou
,
Robert A.
House
,
Peter G.
Bruce
Diamond Proposal Number(s):
[27764, 29028]
Open Access
Abstract: LiNiO2 remains a critical archetypal material for high energy density Li-ion batteries, forming the basis of Ni-rich cathodes in use today. Nevertheless, there are still uncertainties surrounding the charging mechanism at high states of charge and the potential role of oxygen redox. We show that oxidation of O2− across the 4.2 V vs. Li+/Li plateau forms O2 trapped in the particles and is accompanied by the formation of 8% Ni vacancies on the transition metal sites of previously fully dense transition metal layers. Such Ni vacancy formation on charging activates O-redox by generating non-bonding O 2p orbitals and is necessary to form vacancy clusters to accommodate O2 in the particles. Ni accumulates at and near the surface of the particles on charging, forming a Ni-rich shell approximately 5 nm thick; enhanced by loss of O2 from the surface, the resulting shell composition is Ni2.3+1.75O2. The overall Ni oxidation state of the particles measured by XAS in fluorescence yield mode after charging across the plateau to 4.3 V vs. Li+/Li is approximately +3.8; however, taking account of the shell thickness and the shell Ni oxidation state of +2.3, this indicates a Ni oxidation state in the core closer to +4 for compositions beyond the plateau.
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Mar 2024
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