| 1. |
- Touja, Justine, et al.
(författare)
-
Self-supported carbon nanofibers as negative electrodes for K-ion batteries: Performance and mechanism
- 2020
-
Ingår i: Electrochimica Acta. - : Elsevier BV. - 0013-4686. ; 362
-
Tidskriftsartikel (refereegranskat)abstract
- Self-standing carbon nanofibers (CNF) were electrospun and tested in K-ion batteries (KIP). The comparison of the electrochemical performance of KIP using potassium bis(fluorosulfonyl)imide (KFSI) and potassium hexafluorophosphate (KPF6) carbonate-based electrolytes revealed that, despite the coulombic efficiency is more readily stabilized with KFSI than with KPF6, the long-term cycling is quite the same, with a specific capacity of 200 mAh.g(-1) for the CNF electrode. Post-mortem X-ray photoelectron spectroscopy analysis shows a more stable solid electrolyte interphase (SEI) for KIP employing KFSI. Finally, the K+ ion storage mechanism was investigated by combining cyclic voltammetry and operando Raman spectroscopy, showing a combination of adsorption and intercalation processes. The rate capability is, however, better with the KPF6 salt due to SEI layers formed at both CNF and K metal electrode, highlighting that full cell may lead to even superior results.
|
|
| 2. |
- Böhme, Solveig, 1987-
(författare)
-
Fundamental Insights into the Electrochemistry of Tin Oxide in Lithium-Ion Batteries
- 2017
-
Doktorsavhandling (övrigt vetenskapligt/konstnärligt)abstract
- This thesis aims to provide insight into the fundamental electrochemical processes taking place when cycling SnO2 in lithium-ion batteries (LIBs). Special attention was paid to the partial reversibility of the tin oxide conversion reaction and how to enhance its reversibility. Another main effort was to pinpoint which limitations play a role in tin based electrodes besides the well-known volume change effect in order to develop new strategies for their improvement. In this aspect, Li+ mass transport within the electrode particles and the large first cycle charge transfer resistance were studied. Li+ diffusion was proven to be an important issue regarding the electrochemical cycling of SnO2. It was also shown that it is the Li+ transport inside the SnO2 particles which represents the largest limitation. In addition, the overlap between the potential regions of the tin oxide conversion and the alloying reaction was investigated with photoelectron spectroscopy (PES) to better understand if and how the reactions influence each other`s reversibility.The fundamental insights described above were subsequently used to develop strategies for the improvement of the performance and the cycle life for SnO2 electrodes in LIBs. For instance, elevated temperature cycling at 60 oC was employed to alleviate the Li+ diffusion limitation effects and, thus, significantly improved capacities could be obtained. Furthermore, an ionic liquid electrolyte was tested as an alternative electrolyte to cycle at higher temperatures than 60 oC which is the thermal stability limit for the conventional LP40 electrolyte. In addition, cycled SnO2 nanoparticles were characterized with transmission electron microscopy (TEM) to determine the effects of long term high temperature cycling. Also, the effect of vinylene carbonate (VC) as an electrolyte additive on the cycling behavior of SnO2 nanoparticles was studied in an effort to improve the capacity retention. In this context, a recently introduced intermittent current interruption (ICI) technique was employed to measure and compare the development of internal cell resistances with and without VC additive.
|
|
| 3. |
- Mohammadi, Abdolkhaled, et al.
(författare)
-
Assessing Coulombic Efficiency in Lithium Metal Anodes
- 2023
-
Ingår i: Chemistry of Materials. - : American Chemical Society (ACS). - 0897-4756 .- 1520-5002. ; 35:6, s. 2381-2393
-
Tidskriftsartikel (refereegranskat)abstract
- Although lithium metal and anode-free rechargeable batteries (LMBs and AFBs) are phenomenal energy storage systems, the formation of lithium deposits with high surfaces during repeated plating-stripping cycles has hindered their practical applications. Recently, extensive efforts have been made to prevent the growth of high-surface lithium deposition, e.g., electrolyte modification, artificial coating deposition, lithiophilic current collectors, composite lithium metal electrodes, etc. In most of these approaches, Coulombic efficiency (CE) has been used as a quantifiable indicator for the reversibility of the LMBs and AFBs. The interpretation and validation of research results, however, are challenging since the measurement of CE is affected by several parameters related to battery assembly and testing. This study aims to unveil the interplay of several potentially overlooked parameters regulating the CE, such as stripping cutoff voltage, electrolyte quantity, precycling to form a solid electrode interphase (SEI), and electrode surface modification, by applying two alternative electrochemical methods. The hidden aspects of nucleation overpotential revealed by studying these parameters, as well as their influence on the composition and stability of the SEI, are discussed. Overall, this work provides an insightful understanding of the methods and parameters used for assessing the performance of LMBs and AFBs.
|
|
| 4. |
- Mohammadi, Abdolkhaled, et al.
(författare)
-
Measuring the Nucleation Overpotential in Lithium Metal Batteries : Never Forget the Counter Electrode!
- 2022
-
Ingår i: Journal of the Electrochemical Society. - : The Electrochemical Society. - 0013-4651 .- 1945-7111. ; 169:7
-
Tidskriftsartikel (refereegranskat)abstract
- The nucleation overpotential has been used by many researchers as an indicator of the energy required to form the Li nuclei during plating. Typically, a two-electrode system is used to measure the nucleation overpotential; this method, however, fails to show the contribution of working and counter electrodes separately. In this study, we have used a three-electrode configuration (three-dimensional nickel foam as working electrode, lithium foil as both reference and counter electrode) to deconvolute the potential associated with each electrode during the galvanostatic Li electrodeposition to obtain a clear picture of nucleation overpotential. The results indicate that, in such a system, the main source of overpotential is the sudden drop in the potential of the counter electrode, which can be attributed to the extraction of Li from the surface of lithium metal. Moreover, unlike the first half-cycle, the nuclear overpotential is dominated by the working electrode in the second half-discharge cycle, which should account for a true nucleation overpotential of the system. This finding may aid in clarifying the origins of the experimental polarization and preventing researchers from misinterpreting it in terms of nucleation overpotential.
|
|
| 5. |
- Mohammadi, Abdolkhaled, et al.
(författare)
-
Towards understanding the nucleation and growth mechanism of Li dendrites on zinc oxide-coated nickel electrodes
- 2022
-
Ingår i: Journal of Materials Chemistry A. - : Royal Society of Chemistry. - 2050-7488 .- 2050-7496. ; 10:34, s. 17593-17602
-
Tidskriftsartikel (refereegranskat)abstract
- While lithium metal is considered an ideal anode for the next generation of high-energy-density batteries, some major issues such as huge volume change and continuous dendrite formation during lithium plating have hindered its practical applications. Zinc oxide (ZnO) modification of surfaces has shown great potential for inducing a homogeneous Li plating to attain dendrite-free lithium metal anodes. Although considerable improvements in electrochemical performance have been achieved, the detailed mechanism of the evolution of Li nucleation and growth morphology remains elusive. Here, we combine experimental and theoretical calculations to study the Li deposition behaviour during and after the initial nucleation on a thin and uniform layer of ZnO-coated 3D nickel foam. Upon lithiation of the ZnO layer, Li2O and LiZn are formed through a conversion reaction; this composite layer provides specific properties ensuring a homogeneous Li plating. The results showed that dendrite growth not only leads to the formation of cracks on the surface but also provokes the breakoff of some parts of the converted layers from the bulk surface. In addition, no new nucleation occurs upon continued Li deposition, with Li plating mainly taking place on the initial nuclei underneath the protective layer. As a result, large granular Li particles grow at the site of the initial Li nucleation centre, leading to the improvement of electrochemical performances. A deeper understanding of the mechanism of Li nucleation and growth and the morphology of the formed dendrites can help with the development of lithium metal batteries.
|
|
| 6. |
- Tapia-Ruiz, Nuria, et al.
(författare)
-
2021 roadmap for sodium-ion batteries
- 2021
-
Ingår i: Journal of Physics. - : Institute of Physics Publishing (IOPP). - 2515-7655. ; 3:3
-
Tidskriftsartikel (refereegranskat)abstract
- Increasing concerns regarding the sustainability of lithium sources, due to their limited availability and consequent expected price increase, have raised awareness of the importance of developing alternative energy-storage candidates that can sustain the ever-growing energy demand. Furthermore, limitations on the availability of the transition metals used in the manufacturing of cathode materials, together with questionable mining practices, are driving development towards more sustainable elements. Given the uniformly high abundance and cost-effectiveness of sodium, as well as its very suitable redox potential (close to that of lithium), sodium-ion battery technology offers tremendous potential to be a counterpart to lithium-ion batteries (LIBs) in different application scenarios, such as stationary energy storage and low-cost vehicles. This potential is reflected by the major investments that are being made by industry in a wide variety of markets and in diverse material combinations. Despite the associated advantages of being a drop-in replacement for LIBs, there are remarkable differences in the physicochemical properties between sodium and lithium that give rise to different behaviours, for example, different coordination preferences in compounds, desolvation energies, or solubility of the solid-electrolyte interphase inorganic salt components. This demands a more detailed study of the underlying physical and chemical processes occurring in sodium-ion batteries and allows great scope for groundbreaking advances in the field, from lab-scale to scale-up. This roadmap provides an extensive review by experts in academia and industry of the current state of the art in 2021 and the different research directions and strategies currently underway to improve the performance of sodium-ion batteries. The aim is to provide an opinion with respect to the current challenges and opportunities, from the fundamental properties to the practical applications of this technology.
|
|
