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Brennhagen, Anders; Skurtveit, Amalie; Skautvedt, Casper; Cavallo, Carmen; Wragg, David Stephen & Vajeeston, Ponniah
[Show all 9 contributors for this article]
(2024).
Revealing the (de)sodiation mechanisms of Bi-metallates through operando X-ray characterisation.
Show summary
Na-ion batteries is entering the battery market as an alternative to Li-ion batteries. To improve their overall performance it is crucial to develop new types of anode materials with high capacity and long cycle life. Materials combing conversion and alloying mechanisms (CAMs) are promising anodes with their high capacity, but obtaining good cycling stability is still challenging. A comprehensive understanding of the cycling and degradation mechanism of these materials is crucial to improve their performance.
Bi-metallates, with a general formula of Bi−TM−O (TM = transition metal) is a group of ternary CAMs. Their general cycling mechanism consists of an irreversible conversion reaction forming nanoparticles of Bi-metal embedded in a Na-TM-O matrix during the first sodiation, followed by a reversible two-step alloying reaction forming Na3Bi with NaBi as an intermediate phase. In this work, we have used operando X-ray diffraction (XRD), pair distribution function (PDF) analysis and X-ray absorption spectroscopy (XAS) to investigate the desodiation mechanisms of Bi2MoO6 and BiFeO3.
Through this work, we discovered that Bi2MoO6 forms the cubic version of Na3Bi (c-Na3Bi) while BiFeO3 forms hexagonal Na3Bi (h-Na3Bi) in addition to c-Na3Bi during the first sodiation. In the desodiated state, the Bi-particles are partially oxidised, while still maintaining the Bi-metal structure, indicating that it is only the Bi atoms at the interface between the Bi nanoparticles and the Na−TM−O matrix that is oxidised. During cycling the NaxBi particles grow larger thus increasing the distance between them and increasing the impedance in the material. This is considered to be the main driver for the capacity degradation that was observed during the first 20 cycles. The operando XAS data also revealed that Mo6+ in Bi2MoO6 does not change oxidation state during cycling, but changes coordination between tetrahedral and distorted octahedral coordination during cycling. The cycling and degradation mechanisms of Bi2MoO6 is summarised in Figure 1.
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Svelle, Stian; Lundegaard, Lars Fahl; Beato, Pablo & Wragg, David Stephen
(2023).
Case Studies: Crystallography as a Tool for Studying Methanol Conversion in Zeolites,
Springer Handbook of Advanced Catalyst Characterization.
Springer.
ISSN 978-3-031-07125-6.
p. 541–563.
doi:
10.1007/978-3-031-07125-6_26.
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Capel Berdiell, Izar; Wragg, David Stephen; Beato, Pablo; Lundegaard, Lars Fahl; Di Michel, Marco & Svelle, Stian
(2023).
Temperature Programmed Oxidation Probed
with X-ray Diffraction Computed Tomography.
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Svelle, Stian; Capel Berdiell, Izar; Wragg, David Stephen; Beato, Pablo & Lundegaard, Lars Fahl
(2023).
In situ and operando X-ray diffraction as a tool to monitor zeolite catalyst deactivation
.
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Wragg, David Stephen
(2023).
Cleaning Up Operando Battery X-Ray Diffraction With Total Scattering Computed Tomography.
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Skurtveit, Amalie; Pastusic, Andrew; Brennhagen, Anders; Cavallo, Carmen; Wragg, David Stephen & Koposov, Alexey
(2023).
High-Rate Performance of Antimony Chalcogenides (Sb2X3) Studied by Operando X-ray Diffraction (XRD).
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Brennhagen, Anders; Skautvedt, Casper; Cavallo, Carmen; Skurtveit, Amalie; Wragg, David Stephen & Koposov, Alexey
[Show all 9 contributors for this article]
(2023).
Revealing the Cycling and Degradation Mechanism of Bi-Metallates as Anode Materials fro Na-ion Batteries.
Show summary
Na-ion batteries (NIBs) represent an emerging alternative to modern Li-ion batteries. To improve the overall performance of NIBs it is crucial to develop new types of anode materials with high capacity and long cycle life. Among the anode candidates, materials operating under combined conversion and alloying mechanisms (CAMs) are considered as promising. They are capable of delivering high capacity, however, despite theoretical predictions the cycling stability is still below expectations. Therefore, a comprehensive understanding of the cycling and degradation mechanisms of CAMs is crucial to improve their performance. However, these materials undergo multiple chemical transformations, which often involves formation of amorphous and nanocrystalline phases during cycling. Such chemical complexity substantially impedes their full characterization and understanding.
Bismuth metallates, with a general formula of Bi-TM-O (TM = transition metal), is a group of ternary CAMs. Their general cycling mechanism consists of an irreversible conversion reaction, which leads to formation of Bi nanoparticles embedded in a Na-TM-O matrix during the first sodiation. This is followed by a reversible two-step alloying reaction leading to formation of Na3Bi with NaBi as an intermediate phase. In this work, we have used operando X-ray diffraction over the course of ∼30 cycles to study the cycling and degradation mechanisms of two CAMs - Bi2MoO6 and BiFeO3. With the help of ex situ X-ray absorption spectroscopy and pair distribution function (PDF) analysis, we have revealed new insights into these materials in addition to confirming the general cycling mechanism.
Both materials form the cubic phase of Na3Bi (c-Na3Bi) in the sodiated state with some noticeable differences. While, the hexagonal Na3Bi (h-Na3Bi) phase starts to form after 10 cycles in Bi2MoO6, a combination of c-Na3Bi and h-Na3Bi can be observed after the first cycle in BiFeO3. The formation of c-Na3Bi is kinetically favorable in these systems, while h-Na3Bi is the more thermodynamically stable and, therefore, forms later in the cycling process. Both materials shows three distinct regions of capacity degradation, where the first is initiated by a growth in the crystallite sizes of Bi-particles. This is followed by a disappearance of the Bi-phase as the second step. The last degradation phase is related to the disappearance of the NaBi-phase and locking the system in the sodiated state. The present talk will discuss the mechanisms of these degradation steps in view of the future development of CAMs in greater details.
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Brennhagen, Anders; Cavallo, Carmen; Wragg, David Stephen; Koposov, Alexey; Ponniah, Vajeeston & Sjåstad, Anja Olafsen
[Show all 7 contributors for this article]
(2023).
Tracing the (De)sodiation of Bi2MoO6 Through Good and Bad Times With Operando XRD.
Show summary
Na-ion batteries (NIBs) generally have slightly lower energy densities than Li-ion batteries (LIBs), but the abundancy of Na could make NIBs cheaper and more sustainable. The search for new anode materials is essential for further development of NIBs. Anode materials combining conversion and alloying mechanisms (CAMs) are promising because of their high capacity and high rate capabilities, but their complex cycling mechanisms involving amorphous phases are challenging to study [1]. Bi2MoO6 is an example of a CAM that has high initial capacity, but struggles with cycling stability and undergoes major changes during cycling. Detailed understanding of its cycling and degradation mechanism will hopefully enable us to improve the cycling stability of Bi2MoO6 and CAMs in general. Therefore, we have studied Bi2MoO6 using a combination of operando X-ray diffraction (Fig. 1), pair distribution function, X-ray absorption spectroscopy and transmission electron microscopy [3]. This revealed that during the first sodiation, an irreversible conversion of Bi2MoO6 occurs, creating Bi nanoparticles embedded in an amorphous Na-Mo-O matrix. The Bi particles then reversibly alloy with Na, forming cubic Na3Bi leading to a specific capacity close to 300 mAh g−1 for the 10 first cycles. During these cycles, we observe a growth in the crystallite size of the alloying particles, which is probably the leading cause of the rapid capacity decay after cycle 10 where the sodiation of Bi becomes irreversible leaving several inactive Na3Bi particles.
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Capel Berdiell, Izar; König, Nico; Junge, Nicolai Haaber; Kalantzopoulos, Georgios; Beato, Pablo & Svelle, Stian
[Show all 8 contributors for this article]
(2022).
Tracking deactivation level of zeolite H-beta catalysts with novel XRD models.
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Capel Berdiell, Izar; Braghin, Giorgio Bruno; Cordero-Lanzac, Tomas; Beato, Pablo; Lundegaard, Lars Fahl & Wragg, David Stephen
[Show all 8 contributors for this article]
(2022).
Tracking Structural Deactivation of H-Ferrierite Zeolite Catalyst during MTH with XRD.
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Skurtveit, Amalie; Cavallo, Carmen; Wragg, David Stephen & Koposov, Alexey
(2022).
Revealing the (de)sodiation mechanism of antimony chalcogenides Sb2X3 with operando XRD.
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Wragg, David Stephen
(2022).
Big Data in XRD: Processing a huge number of sub optimal datasets with TOPAS.
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Brennhagen, Anders; Cavallo, Carmen; Wragg, David Stephen; Koposov, Alexey; Ponniah, Vajeeston & Sjåstad, Anja Olafsen
[Show all 7 contributors for this article]
(2022).
Tracing the (De)sodiation of Bi2MoO6 Through Good and Bad Times With Operando XRD.
Show summary
Anode materials combining conversion and alloying mechanisms (CAMs) are promising for Na-ion batteries, but their complex cycling mechanisms are challenging to study. Understanding the (de)sodiation mechanism is crucial and, in several cases, requires advanced synchrotron characterization. Operando synchrotron studies are generally limited to one or two sodiation cycles, which are not fully comprehensive for CAMs. Therefore, herein, we studied the sodiation and desodiation of Bi2MoO6-based anodes with laboratory-based operando X-ray diffraction exceeding more than 30 cycles to have a complete overview of our CAM’s mechanism. This revealed important aspects of the cycling and degradation mechanisms in the material. During the first sodiation, an irreversible conversion of Bi2MoO6 occurs, creating Bi nanoparticles embedded in an amorphous Na-Mo-O matrix. The Bi particles then reversibly alloy with Na forming cubic Na3Bi leading to a specific capacity close to 300 mAh g−1 for the 10 first cycles. This is followed by a rapid capacity decay where the sodiation of Bi becomes irreversible leaving several inactive Na3Bi particles. To the best of our knowledge, this is due to the observed crystal growth of the Bi particles accompanied by structural changes in the insulating Na-Mo-O leading to poor conductivity in the electrodes. The poor electronic conductivity of the matrix deactivates the NaxBi particles and prevents the formation of the solid electrolyte interface layer as shown by post-mortem scanning electron microscopy studies.
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Brennhagen, Anders; Cavallo, Carmen; Wragg, David Stephen; Ponniah, Vajeeston; Sjåstad, Anja Olafsen & Koposov, Alexey
[Show all 7 contributors for this article]
(2022).
Tracing the (de)sodiation of Bi2MoO6 through good and bad times with operando XRD.
Show summary
Anode materials combining conversion and alloying mechanisms (CAMs) are promising for Na-ion batteries, but their complex cycling mechanisms are challenging to study1. Understanding the (de)sodiation mechanism is crucial and, in several cases, requires advanced synchrotron characterization. Operando synchrotron studies are generally limited to one or two sodiation cycles, which are not fully comprehensive for CAMs2. Therefore, herein, we studied the sodiation and desodiation of Bi2MoO6-based anodes with laboratory-based operando X-ray diffraction exceeding more than 30 cycles to have a complete overview of our CAM’s mechanism (Figure 1)3. This revealed important aspects of the cycling and degradation mechanisms in the material. During the first sodiation, an irreversible conversion of Bi2MoO6 occurs, creating Bi nanoparticles embedded in an amorphous Na-Mo-O matrix. The Bi particles then reversibly alloy with Na forming cubic Na3Bi leading to a specific capacity close to 300 mAh g−1 for the 10 first cycles. This is followed by a rapid capacity decay where the sodiation of Bi becomes irreversible leaving several inactive Na3Bi particles. To the best of our knowledge, this is due to the observed crystal growth of the Bi particles accompanied by structural changes in the insulating Na-Mo-O leading to poor conductivity in the electrodes. The poor electronic conductivity of the matrix deactivates the NaxBi particles and prevents the formation of the solid electrolyte interface layer as shown by post-mortem scanning electron microscopy studies.
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Brennhagen, Anders; Cavallo, Carmen; Wragg, David Stephen; Koposov, Alexey; Ponniah, Vajeeston & Sjåstad, Anja Olafsen
[Show all 7 contributors for this article]
(2021).
Operando XRD study on Bi2MoO6 as anode material for Na-ion batteries.
Show summary
Na-ion batteries (NIBs) could be a good alternative to Li-ion batteries (LIBs) due to the large abundance and availability of sodium resources. The search for good anode materials is one of the big challenges since graphite, which is the most common anode material for LIB, does not work well in NIBs. We are developing Bi2MoO6 as an anode material for NIBs, and will explain the main cycling mechanism. By utilizing a combination of conversion and alloying reactions, the material achieves high capacity while still maintaining a decent cycling stability. The complex cycling mechanism also makes it an interesting and challenging material to characterize during cycling. In this poster, we present high quality operando XRD data of the material during several cycles, acquired in the home lab. The data clearly shows that the reversible alloying reaction of Bi-metal to cubic Na3Bi gives the main capacity contribution, after the initial conversion reaction. This indicates formation of nanocrystalline Bi-particles, as nanocrystalline Bi-metal has shown the same reaction mechanism while microcrystalline Bi instead forms the hexagonal phase of Na3Bi. The molybdenum goes into an amorphous matrix that is only partially electrochemically active. The phases formed with molybdenum during cycling are difficult to characterize, due to their amorphous nature, and remain an unsolved mystery.
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Brennhagen, Anders; Cavallo, Carmen; Wragg, David Stephen; Sjåstad, Anja Olafsen; Ponniah, Vajeeston & Fjellvåg, Helmer
(2021).
Operando XRD studies on Bi2MoO6 as anode material for Na-ion batteries.
Show summary
Na-ion batteries (NIBs) could be a good alternative to Li-ion batteries (LIBs) due to the large abundance and availability of sodium resources. The search for good anode materials is one of the big challenges since graphite, which is the most common anode material for LIB, does not work well in NIBs. We are developing Bi2MoO6 as an anode material for NIBs, and will explain the main cycling mechanism. By utilizing a combination of conversion and alloying reactions, the material achieves high capacity while still maintaining a decent cycling stability. The complex cycling mechanism also makes it an interesting and challenging material to characterize during cycling. In this poster, we present high quality operando XRD data of the material during several cycles, acquired in the home lab. The data clearly shows that the reversible alloying reaction of Bi-metal to cubic Na3Bi gives the main capacity contribution, after the initial conversion reaction. This indicates formation of nanocrystalline Bi-particles, as nanocrystalline Bi-metal has shown the same reaction mechanism while microcrystalline Bi instead forms the hexagonal phase of Na3Bi. The molybdenum goes into an amorphous matrix that is only partially electrochemically active. The phases formed with molybdenum during cycling are difficult to characterize, due to their amorphous nature, and remain an unsolved mystery.
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Brennhagen, Anders; Cavallo, Carmen; Wragg, David; Vajeeston, Ponniah; Sjåstad, Anja Olafsen & Fjellvåg, Helmer
(2021).
Bi4V2O11/RGO composite as conversion and alloying
anode for Na-ion batteries.
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Brennhagen, Anders; Wragg, David; Fjellvåg, Helmer; Vajeeston, Ponniah; Sjåstad, Anja Olafsen & Cavallo, Carmen
(2021).
Beyond Insertion: Conversion alloying Bi/RGO-based materials as novel anodes for Na-ion batteries.
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Wragg, David
(2020).
Beamline Facilities for Chemistry and Materials Science.
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Wragg, David; Fjellvåg, Øystein; Fjellvåg, Helmer; Sottmann, Jonas; Vaughan, Gavin B M & Di Michel, Marco
[Show all 7 contributors for this article]
(2020).
Operando Total Scattering Computed Tomography: Making the Invisible Visible
.
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Cavallo, Carmen; Brennhagen, Anders; Wragg, David & Fjellvåg, Helmer
(2020).
Beyond Insertion: Conversion alloying Bi/RGO-based materials as anode for Na-ion batteries
.
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Beale, Andrew M.; Lezcano-González, Inés; Slawinski, Wojciech Andrzej & Wragg, David Stephen
(2019).
Correction: Correlation between Cu ion migration behaviour and deNOx activity in Cu-SSZ-13 for the standard NH3-SCR reaction (Chemical Communications (2016) 52 (6170-6173) DOI: 10.1039/c6cc00513f).
Chemical Communications.
ISSN 1359-7345.
55(11),
p. 1667–1667.
doi:
10.1039/c9cc90036e.
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Wragg, David; Fjellvåg, Øystein; Ruud, Amund; Fjellvåg, Helmer; Vajeeston, Ponniah & Vaughan, Gavin B M
[Show all 9 contributors for this article]
(2019).
XRD/PDF computed tomography and how to get the best possible operando data from ion batteries.
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Wragg, David
(2019).
Be prepared!How an Advanced Home Lab can Improve Our Synchrotron Science.
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Wragg, David; Ruud, Amund; Fjellvåg, Øystein; Fjellvåg, Helmer; lebedev, Oleg & Di Michel, Marco
[Show all 9 contributors for this article]
(2019).
PDF Analysis of Batteries Using Diffraction Computed Tomography.
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Wragg, David; Ruud, Amund; Fjellvåg, Helmer; Fjellvåg, Øystein; Vajeeston, Ponniah & Sottmann, Jonas
[Show all 9 contributors for this article]
(2019).
PDF Analysis of Batteries Using Diffraction Computed Tomography.
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Wragg, David; Sottmann, Jonas; Ruud, Amund; Fjellvåg, Øystein & Vaughan, Gavin B M
(2018).
Combined refinement of XRD and PDF data from nanomaterials.
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Strandbakke, Ragnar; Wragg, David; Carvalho, Patricia; Mielewczyk-Gryn, Aleksandra; Wachowski, Sebastian & Balaguer, Maria
[Show all 8 contributors for this article]
(2018).
Coupled hydration and red-ox in MIEC BGLC perovskites .
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Kalantzopoulos, Georgios N.; Lundvall, Fredrik; Nyborg Broge, Nils Lau; Søndergaard-Pedersen, Frederik M; Lind, Anna Maria & Arstad, Bjørnar
[Show all 9 contributors for this article]
(2018).
Real-Time Evolution of SAPO Catalysts' Local Coordination during Hydrothermal Treatment.
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Wragg, David; Sottmann, Jonas; Vajeeston, Ponniah & Ruud, Amund
(2017).
The intriguing mechanism of phosphorus anodes for sodium ion batteries Revealed by operando pair distribution function and X-ray diffraction computed tomography.
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Lundvall, Fredrik; Kalantzopoulos, Georgios N.; Wragg, David; Arstad, Bjørnar; Blom, Richard & Sjåstad, Anja Olafsen
[Show all 7 contributors for this article]
(2017).
Dawsonite as sorbent for the SEWGS process.
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Kalantzopoulos, Georgios N.; Lundvall, Fredrik; Lind, Anna Maria; Arstad, Bjørnar; Wragg, David & Fjellvåg, Helmer
(2017).
Sub-unit cell structural transformations during template-removal and hydration of SAPO-37 microporous catalysts.
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Lundvall, Fredrik; Kalantzopoulos, Georgios N.; Wragg, David; Arstad, Bjørnar; Blom, Richard & Sjåstad, Anja Olafsen
[Show all 7 contributors for this article]
(2017).
Finding new materials for the SEWGS process.
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Lundvall, Fredrik; Kalantzopoulos, Georgios N.; Wragg, David; Arstad, Bjørnar; Blom, Richard & Sjåstad, Anja Olafsen
[Show all 7 contributors for this article]
(2017).
Thermogravimetric analysis – a viable method for screening materials for the SEWGS process.
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Kalantzopoulos, Georgios N.; Lundvall, Fredrik; Hill, Adam; Lind, Anna Maria; Arstad, Bjørnar & Attfield, Martin P.
[Show all 9 contributors for this article]
(2017).
CATalyst transformations and LIFEtime by in-situ techniques and modelling (CATLIFE).
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Kalantzopoulos, Georgios N.; Lundvall, Fredrik; Lind, Anna Maria; Arstad, Bjørnar; Chernyshov, Dmitry & Wragg, David
[Show all 7 contributors for this article]
(2017).
High time-resolution in-situ methods for tracking structural transformations in SAPO materials.
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Wragg, David; Sottmann, Jonas; Vajeeston, Ponniah; Sørby, Magnus Helgerud & Fjellvåg, Helmer
(2016).
Does the 3D Topological Dirac Semimetal Na3P Have More Than One Ground State?
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Lundvall, Fredrik; Kalantzopoulos, Georgios N.; Wragg, David; Arstad, Bjørnar; Blom, Richard & Sjåstad, Anja Olafsen
[Show all 7 contributors for this article]
(2016).
Thermogravimetric analysis – a viable method for screening materials for the SEWGS process.
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Wragg, David; Sottmann, Jonas; Vajeeston, Ponniah; Emerich, Hermann; Fjellvåg, Helmer & Hermann, Matthias
[Show all 9 contributors for this article]
(2016).
Size Matters: How crystallite size controls reaction path in the sodium bismuth anode system.
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Strandbakke, Ragnar; Vøllestad, Einar; Prato, Rafael Alberto; Wragg, David; Sartori, Sabrina & Norby, Truls
(2016).
Structural and electrochemical properties of hydrated mixed conductor Ba1-xGd0.8La0.2+xCo2O6-d.
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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.
Kjemisk Institutt.
Show summary
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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