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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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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I11-High Resolution Powder Diffraction
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Diamond Proposal Number(s):
[25166]
Open Access
Abstract: Solid-state electrolytes (SEs) hold the potential to overcome challenges that hinder the commercialization of lithium-sulfur batteries. However, their limited ionic conductivity makes lithium (Li) ion transport a critical bottleneck in accessing the superior capacity of sulfur. In this study, we investigate high-entropy Cl,Br-co-doped sulfide argyrodites as SEs in Li-sulfur (S) all-solid-state batteries (ASSBs).
exhibits an ionic conductivity of 6.9 mS
at room temperature with an activation energy of 0.28 eV, thanks to its high configurational entropy. The electrolyte with suitable cathodic stability and high ionic conductivity allows S composite cathodes to deliver an areal capacity over 6 mAh
when cycled with Li-In anodes. The reduced porosity of the SE separator and the formation of a passivating interphase with metallic Li enable Li-S ASSBs to cycle without short circuits, achieving an S utilization of over 75% at 0.1 C.
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Oct 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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I21-Resonant Inelastic X-ray Scattering (RIXS)
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Diamond Proposal Number(s):
[25785]
Open Access
Abstract: Oxygen redox cathodes, such as Li1.2Ni0.13Co0.13Mn0.54O2, deliver higher energy densities than those based on transition metal redox alone. However, they commonly exhibit voltage fade, a gradually diminishing discharge voltage on extended cycling. Recent research has shown that, on the first charge, oxidation of O2− ions forms O2 molecules trapped in nano-sized voids within the structure, which can be fully reduced to O2− on the subsequent discharge. Here we show that the loss of O-redox capacity on cycling and therefore voltage fade arises from a combination of a reduction in the reversibility of the O2−/O2 redox process and O2 loss. The closed voids that trap O2 grow on cycling, rendering more of the trapped O2 electrochemically inactive. The size and density of voids leads to cracking of the particles and open voids at the surfaces, releasing O2. Our findings implicate the thermodynamic driving force to form O2 as the root cause of transition metal migration, void formation and consequently voltage fade in Li-rich cathodes.
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Mar 2024
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B07-B1-Versatile Soft X-ray beamline: High Throughput ES1
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Conor M. E.
Phelan
,
Erik
Bjorklund
,
Jasper
Singh
,
Michael
Fraser
,
Prvanin N.
Didwal
,
Gregory J.
Rees
,
Zachary
Ruff
,
Pilar
Ferrer
,
David C.
Grinter
,
Clare P.
Grey
,
Robert S
Weatherup
Diamond Proposal Number(s):
[33283]
Open Access
Abstract: The cathode–electrolyte interphase (CEI) in Li-ion batteries plays a key role in suppressing undesired side reactions while facilitating Li-ion transport. Ni-rich layered cathode materials offer improved energy densities, but their high interfacial reactivities can negatively impact the cycle life and rate performance. Here we investigate the role of electrolyte salt concentration, specifically LiPF6 (0.5–5 m), in altering the interfacial reactivity of charged LiN0.8Mn0.1Co0.1O2 (NMC811) cathodes in standard carbonate-based electrolytes (EC/EMC vol %/vol % 3:7). Extended potential holds of NMC811/Li4Ti5O12 (LTO) cells reveal that the parasitic electrolyte oxidation currents observed are strongly dependent on the electrolyte salt concentration. X-ray photoelectron and absorption spectroscopy (XPS/XAS) reveal that a thicker LixPOyFz-/LiF-rich CEI is formed in the higher concentration electrolytes. This suppresses reactions with solvent molecules resulting in a thinner, or less-dense, reduced surface layer (RSL) with lower charge transfer resistance and lower oxidation currents at high potentials. The thicker CEI also limits access of acidic species to the RSL suppressing transition-metal dissolution into the electrolyte, as confirmed by nuclear magnetic resonance (NMR) spectroscopy and inductively coupled plasma optical emission spectroscopy (ICP-OES). This provides insight into the main degradation processes occurring at Ni-rich cathode interfaces in contact with carbonate-based electrolytes and how electrolyte formulation can help to mitigate these.
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Mar 2024
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labSAXS-Offline SAXS and Sample Environment Development
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Diamond Proposal Number(s):
[29810]
Open Access
Abstract: Optimising the composite cathode for next-generation, safe solid-state batteries with inorganic solid electrolytes remains a key challenge towards commercialisation and cell performance. Tackling this issue requires the design of suitable polymer binders for electrode processability and long-term solid–solid interfacial stability. Here, block-polyester/carbonates are systematically designed as Li-ion conducting, high-voltage stable binders for cathode composites comprising of single-crystal LiNi0.8Mn0.1Co0.1O2 cathodes, Li6PS5Cl solid electrolyte and carbon nanofibres. Compared to traditional fluorinated polymer binders, improved discharge capacities (186 mA h g−1) and capacity retention (96.7% over 200 cycles) are achieved. The nature of the new binder electrolytes also enables its separation and complete recycling after use. ABA- and AB-polymeric architectures are compared where the A-blocks are mechanical modifiers, and the B-block facilitates Li-ion transport. This reveals that the conductivity and mechanical properties of the ABA-type are more suited for binder application. Further, catalysed switching between CO2/epoxide A-polycarbonate (PC) synthesis and B-poly(carbonate-r-ester) formation employing caprolactone (CL) and trimethylene carbonate (TMC) identifies an optimal molar mass (50 kg mol−1) and composition (wPC 0.35). This polymer electrolyte binder shows impressive oxidative stability (5.2 V), suitable ionic conductivity (2.2 × 10−4 S cm−1 at 60 °C), and compliant viscoelastic properties for fabrication into high-performance solid composite cathodes. This work presents an attractive route to optimising polymer binder properties using controlled polymerisation strategies combining cyclic monomer (CL, TMC) ring-opening polymerisation and epoxide/CO2 ring-opening copolymerisation. It should also prompt further examination of polycarbonate/ester-based materials with today's most relevant yet demanding high-voltage cathodes and sensitive sulfide-based solid electrolytes.
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Jan 2024
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