| 1. |
- Le Pham, Phuong Nam, et al.
(författare)
-
Potassium-ion batteries using KFSI/DME electrolytes: Implications of cation solvation on the K + -graphite (co-)intercalation mechanism
- 2022
-
Ingår i: Energy Storage Materials. - : Elsevier BV. - 2405-8297. ; 45, s. 291-300
-
Tidskriftsartikel (refereegranskat)abstract
- Recently potassium-ion batteries have been proposed as a promising next generation battery technology owing to cost effectiveness and a wide range of electrode materials as well as electrolytes available. Potassium bis(fluorosulfonyl)imide (KFSI) in monoglyme (DME) is one potential electrolyte, wherein the K+ solvation heavily depends on the salt concentration and strongly affects the electrochemistry. Pure K+ intercalation occurs for highly concentrated electrolytes (HCEs), while co-intercalation is dominant for less concentrated electrolytes. The mechanisms are easily distinguished by their galvanostatic curves as well as by operando XRD. Here Raman spectroscopy coupled with computational chemistry is used to provide in-depth knowledge about the cation solvation for a wide concentration range, all the way up to 5 M KFSI in DME. Starting from pure DME experimental and computed Raman spectra provides a detailed conformational assignment enabling us to calculate the solvation number (SN) of K+ by DME as a function of salt concentration for all the electrolytes. For low to medium KFSI concentrations, the SN is approximately constant, ca. 2.7, and/as there is a surplus of DME solvent available, while for HCEs, with much less DME available, the SN is <2. This reduced SN results in a thermodynamically more favored desolvation at the graphite surface, leading to intercalation, as compared to the higher SN of conventional electrolytes leading to co-intercalation, as observed also by electrochemical cycling.
|
|
| 2. |
- Le Pham, Phuong Nam, et al.
(författare)
-
Prussian blue analogues for potassium-ion batteries: insights into the electrochemical mechanisms
- 2023
-
Ingår i: Journal of Materials Chemistry A. - : Royal Society of Chemistry (RSC). - 2050-7488 .- 2050-7496. ; 11:6, s. 3091-3104
-
Tidskriftsartikel (refereegranskat)abstract
- A comprehensive description of the electrochemical mechanisms of the Prussian Blue Analogue (PBA) K1.67Mn0.65Fe0.35[Fe(CN)6]0.92·0.45H2O is obtained by combining several complementary ex situ and operando physico-chemical characterisation techniques. This particular PBA, which shows very good electrochemical performance as a cathode material in potassium-ion batteries (PIBs), undergoes three successive redox reactions during the (de-)potassiation that are hereby identified by ex situ57Fe Mössbauer spectroscopy and operando Mn and Fe K-edge X-ray absorption spectroscopy. These reactions come along with notable modifications of the crystal structure, which are followed in real time by operando X-ray diffraction. The correlation of these results, interpreted with the support of chemometric methods, also reveals the limitations of this PBA, probably related to the deactivation of the Mn undergoing extensive reversible Jahn-Teller distortion during cycling as well as possible dissolution in the electrolyte. These results underline that optimisation of the chemical composition of PBAs is a crucial step towards the preparation of reliable and stable PBA-based cathodes for PIBs.
|
|
| 3. |
- Luu, Chinh, et al.
(författare)
-
Framework of Spatial Flood Risk Assessment for a Case Study in Quang Binh Province, Vietnam
- 2020
-
Ingår i: Sustainability. - Switzerland : MDPI. - 2071-1050. ; 12:7, s. 1-17
-
Tidskriftsartikel (refereegranskat)abstract
- Vietnam has been extensively affected by floods, suffering heavy losses in human life andproperty. While the Vietnamese government has focused on structural measures of flood defence such as levees and early warning systems, the country still lacks flood risk assessment methodologies and frameworks at local and national levels. In response to this gap, this study developed a flood risk assessment framework that uses historical flood mark data and a high- resolution digital elevation model to create an inundation map, then combined this map with exposure and vulnerability data to develop a holistic flood risk assessment map. The case study is the October 2010 flood event in Quang Binh province, which caused 74 deaths, 210 injuries, 188,628 flooded properties, 9019 ha of submerged and damaged agricultural land, and widespread damages to canals, levees, and roads. The final flood risk map showed a total inundation area of 64348 ha, in which 8.3% area of low risk, 16.3% area of medium risk, 12.0% area of high risk, 37.1% area of very high risk, and 26.2% area of extremely high risk. The holistic flood risk assessment map of QuangBinh province is a valuable tool and source for flood preparedness activities at the local scale.
|
|
