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• North, Erlend Tiberg; Skautvedt, Casper; Thiagarajan, Abilash Kanish; Michiel, Marco Di; Checchia, Stefano & Koposov, Alexey [Vis alle 7 forfattere av denne artikkelen] (2025). X-ray Beam Damage Effects in a Lithium-Ion Battery Probed by Spatially Resolved X-ray Diffraction. ACS Energy Letters. 10(10), s. 4930–4932. doi: 10.1021/acsenergylett.5c02442. Fulltekst i vitenarkiv Vis sammendrag

  The use of synchrotron radiation has become common for probing the structural changes in rechargeable batteries, particularly for operando analysis. Herein, we report the exposure of the electrode to high photon flux during an operando study shutting down electrochemical transformations in the irradiated area of an electrode and causing a gradient of lithiation around the operando beam position. We rationalize such beam damage through radiation induced ionization and, consequently, electrolyte decomposition.

• Meyer, Lea C.; Thiagarajan, Abilash Kanish; Koposov, Alexey & Balducci, Andrea (2025). Unravelling the mechanism of potassium-ion storage into graphite through electrolyte engineering. Energy Storage Materials. ISSN 2405-8297. 75. doi: 10.1016/j.ensm.2025.104021. Fulltekst i vitenarkiv Vis sammendrag

  Graphite is one of the most widely used anode materials in potassium-ion batteries (PIBs). However, the exact mechanism of K+ions intercalation into graphite has not yet been fully understood. In addition, the intercalation process strongly depends on the selection of the electrolyte system. In this work, we evaluated the use of an electrolyte containing 1.5 M potassium bis(fluorosulfonyl)imide (KFSI) dissolved in a mixture of propylene carbonate (PC)/ 1,1,2,2-tetraethoxyethane (TEG)/ vinyl ethylene carbonate (VEC) (62:36:2 vol.%). Using such an electrolyte system it was possible to obtain experimental evidence for the formation of KC16 during the potassium intercalation and deintercalation using in situ Raman spectroscopy and operando X-ray diffraction (XRD). The results are supported by the visual observation of a color change of the graphite electrode surface during the intercalation of K+ ions into the graphite lattice. In addition, it has been demonstrated that the selected electrolyte system eliminates the co-intercalation of the solvent into the graphite structure.

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• Wragg, David Stephen; Koposov, Alexey; Thiagarajan, Abilash Kanish; Chernyshov, Dmitry; Brennhagen, Anders & Slawinski, Wojciech Andrzej [Vis alle 7 forfattere av denne artikkelen] (2024). Structural Origins of Graphite Staging. Fulltekst i vitenarkiv
• North, Erlend Tiberg; Skautvedt, Casper; Thiagarajan, Abilash Kanish; Checchia, Stefano; Koposov, Alexey & Wragg, David Stephen (2024). Spatially Resolved Beam Damage on a Graphite Anode in Operando. Fulltekst i vitenarkiv Vis sammendrag

  Modern synchrotron beam lines can offer higher luminance and energy, providing more opportunities for scientists performing structural analysis of materials. However, this benefit comes with a risk of questionable results as continual exposure can lead to damage to the studied materials. This effect is well established in protein crystallography but has recently gained attention in the field of material science including operando studies of battery materials. We have investigated the electrochemical cycling of a graphite-based anode for Li-ion batteries under continuous exposure to high-energy X-ray radiation, exploring the consequences of the exposure on the structure and cycling capabilities. We analyze damage by correlating the dose of radiation to the inhibition of electrochemistry.

• Thiagarajan, Abilash Kanish; Brennhagen, Anders; Wragg, David Stephen & Koposov, Alexey (2023). Structural changes in graphite-based anodes of Li-ion batteries elucidated through operando XRD. Universitetet i Oslo. Fulltekst i vitenarkiv Vis sammendrag

  Lithium-ion batteries (LIBs) with graphite-based anodes dominate the battery market around the world and have been studied extensively for the past decades, but the structural changes during cycling are still not fully understood. In this work, we used galvanostatic cycling (GC) to characterize the electrochemical performance of graphite samples in LIB. We also attempted to achieve stable capacities over hundreds of cycles to monitor the effect of long-term cycling on the mechanisms of graphite, with limited success. The fabricated coin cells experienced poor capacity retention across all graphite samples and some abnormal capacity increases that had not been observed previously. We noticed that electrolytes containing FEC made a noticeable change to the electrochemical performance as it resulted in irregular cycling, but also better capacity retention. Operando X-ray diffraction is a powerful technique to understand structural changes. We looked at multiple graphite reflections, mainly 002, 100, 101, 102 and 004, and observed that the expansion of the structure is not only 2 dimensions but all 3 dimensions as the interlayer distance and graphene layers expands during lithiation. We also monitored this expansion of graphene layers with pair distribution function (PDF) as the three C-C distances in hexagonal carbon rings, 1.41 Å, 2.41 Å and 2.85 Å, changed lengths at different points during lithiation and delithiation. We looked at diffraction peaks during lithiation and delithiation to study the mechanisms and observed that they were different. Lithiation showed solid solution like behavior indicating disordered intermediate phases, while delithiation showed two-phase transition indicating ordered structures. In this work we have used Operando X-ray diffraction to show that the structural changes graphite undergoes during cycling, transition from graphite to LiC6, is not specific to each graphite sample and the structural changes depend on the condition of the material. Pristine graphite samples transitioned fully to LiC6 during cycling with C-rate of C/6, but only LiC12 when a higher C-rate of C/2 was used. Graphite electrodes cut from commercial pouch cells that had cycled many hundreds of electrochemical cycles were able to transition to LiC6 during C/20, but only LiC12 during C/6, indicating an “ageing” mechanism.

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