| 1. |
- Mathew, Alma, et al.
(författare)
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Understanding the Capacity Fade in Polyacrylonitrile Binder-based LiNi0.5Mn1.5O4 Cells
- 2022
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Ingår i: Batteries & Supercaps. - : John Wiley & Sons. - 2566-6223. ; 5:12
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Tidskriftsartikel (refereegranskat)abstract
- Abstract Binders are electrochemically inactive components that have a crucial impact in battery ageing although being present in only small amounts, typically 1?3?% w/w in commercial products. The electrochemical performance of a battery can be tailored via these inactive materials by optimizing the electrode integrity and surface chemistry. Polyacrylonitrile (PAN) for LiNi0.5Mn1.5O4 (LNMO) half-cells is here investigated as a binder material to enable a stable electrode-electrolyte interface. Despite being previously described in literature as an oxidatively stable polymer, it is shown that PAN degrades and develops resistive layers within the LNMO cathode. We demonstrate continuous internal resistance increase in LNMO-based cells during battery operation using intermittent current interruption (ICI) technique. Through a combination of on-line electrochemical mass spectrometry (OEMS) and X-ray photoelectron spectroscopy (XPS) characterization techniques, the degradation products can be identified as solid on the LNMO electrode surface, and no excessive gas formation seen. The increased resistance and parasitic processes are correlated to side-reactions of the PAN, possibly intramolecular cyclization, which can be identified as the main cause of the comparatively fast capacity fade.
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| 2. |
- Mikheenkova, Anastasiia, et al.
(författare)
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Resolving high potential structural deterioration in Ni-rich layered cathode materials for lithium-ion batteries operando
- 2023
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Ingår i: Journal of Energy Storage. - : Elsevier. - 2352-152X .- 2352-1538. ; 57
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Tidskriftsartikel (refereegranskat)abstract
- LixNi0.90Co0.05Al0.05O2 (NCA) extracted from an automotive battery cell is studied using a combination of in-house operando techniques to understand the correlation between gas evolution and structural collapse when NCA is cycled to high potentials in a lithium-ion battery configuration. The operando techniques comprise X-ray diffraction (XRD) and online electrochemical mass spectrometry (OEMS), and cycled using intermittent current interruption (ICI). The ICI cycling protocol is used to assess the dynamic change in resistance as well as to provide a validation of the operando setups. Both gas evolution and structural collapse have previously been observed as degradation mechanisms of Ni-rich electrodes including NCA, however, their causal link is still under debate. Here our presented results show a correlation between the decrease of the interlayer distance in NCA with both an increase in CO2 evolution and diffusion resistance above 4.1 V. Additionally, particle cracking, which is a mechanism often correlated with gas evolution, was found to be reversible and visible before gas evolution and Li diffusion resistance increase. The ICI technique is shown to be useful for the correlation of operando experiments on parallel setups and evaluation of mass transport dependent processes.
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| 3. |
- Misiewicz, Casimir, et al.
(författare)
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Online electrochemical mass spectrometry on large-format Li-ion cells
- 2023
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Ingår i: Journal of Power Sources. - : Elsevier. - 0378-7753 .- 1873-2755. ; 554
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Tidskriftsartikel (refereegranskat)abstract
- Advances in methodologies for real-time analysis of batteries have come a long way, especially with the development of Operando Electrochemical Mass Spectrometry (OEMS). These approaches allow for the deter-mination of side reactions during battery cycling with unprecedented selectivity and sensitivity, providing vital information necessary for determination of lifetime-limiting processes. However, the work thus far has primarily been carried out on model battery systems, where cell atmospheres are largely altered (through open flow, closed cell, and intermittent sampling approaches) and operation conditions are therefore not comparable with real-life situations. Herein, the development and validation of an intermittently closed OEMS system adapted for readily available commercial batteries is showcased. We provide a detailed description of a unique analysis design for large-format PHEV2 cells, with subsequent pressure and gassing data. A qualitative analysis of the results shows that side reactions brought on by structural transitions within both electrodes can be clearly observed. Transi-tions causing large volume changes in graphite induce H2 and C2H4 as SEI reformation products while the c lattice collapse in NMC induces CO2 evolution (through O2 release). OEMS can therefore be used for the quick and effective study of commercially available rechargeable batteries without influencing the internal battery chemistry.
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| 4. |
- Scharf, Janik, et al.
(författare)
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Gas evolution in large-format automotive lithium-ion battery during formation : Effect of cell size and temperature
- 2024
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Ingår i: Journal of Power Sources. - : Elsevier. - 0378-7753 .- 1873-2755. ; 603
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Tidskriftsartikel (refereegranskat)abstract
- Optimization of cell formation during lithium -ion battery (LIB) production is needed to reduce time and cost. Operando gas analysis can provide unique insights into the nature, extent, and duration of the formation process. Herein we present the development and application of an Online Electrochemical Mass Spectrometry (OEMS) design capable of monitoring gas evolution and consumption in both model coin-cells (Q = 0.72 mAh) with a graphite/electrolyte weight-ratio of 1:12.5 and large-format Li -ion cells (Q = 72 Ah) with a graphite/electrolyte weight -ratio of 1:0.63 during operation. Although the composition and amounts of gas are highly comparable, even when validated against ex -situ analysis, the gas release rate is lower from the larger cell size and likely limited by gas bubble transport through the electrode stack of the cell during formation. Higher temperatures accelerate the formation process, but also alters the composition and extent of gas released. Apart from providing novel insights into the formation processes of large -format Li-ion cells, our OEMS setup offers an opportunity for the battery manufacturing and automotive industry to explore the impact of battery formation and/or operating conditions on gas evolution in next -generation Li-ion batteries of any size.
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