1,720,971 research outputs found
Understanding the desing, synthesis and properties of novel Na ion conducting electrolytes
No full textnot availabl
Understanding the desing, synthesis and properties of novel Na ion conducting electrolytes
No full textnot availabl
Sodium-Ion Batteries
No full textResearch Foundation Flanders (FWO Vlaanderen , project G053519N),
FWO Strategic Basic Research Grant of MSc. Jonas Mercken (1S08921N),
UHasselt BOF grant of MSc. Jonas Mercke
Sodium-Ion Batteries
No full textResearch Foundation Flanders (FWO Vlaanderen , project G053519N),
FWO Strategic Basic Research Grant of MSc. Jonas Mercken (1S08921N),
UHasselt BOF grant of MSc. Jonas Mercke
Electrolytes for lithium and sodium ion batteries: the road from ionic liquids to deep eutectic solvents and from solid ionogels to eutectogels.
No full textElectrolytes for lithium and sodium ion batteries: the road from ionic liquids to deep eutectic solvents and from solid ionogels to eutectogels.
An Hardy, Jonas Mercken, An-Sofie Kelchtermans, Bjorn Joos, Dries De Sloovere, Marlies K. Van Bael
In order to increase the energy density as well as the safety of alkali ion batteries, efforts over the past years have focused on solid electrolytes, mainly for Li+ conduction. Among these, the solid composite electrolyte (SCE) consists of a liquid immobilized in a solid skeleton, for example the ionogel which confines an ionic liquid within an inorganic or hybrid solid matrix.
Since deep eutectic solvents have advantages over ionic liquids, such as ease of preparation, cost etc. we proposed a eutectogel (ETG) for lithium ion batteries composed of a DES (LiTFSI/NMA) in a solid silica matrix with a high ionic conductivity of 1.46 mS/cm, high thermal (130°C) and electrochemical stability (up to 4.8V) . However, these materials also are brittle, which in the final cell will influence the interfacial resistance as the contact with the electrode may be limited, besides cracking, limiting the cell performance. Therefore, two strategies were followed for improvement.
First, the silica matrix was replaced by a polymer matrix, called the P-ETG, achieving 0.78 mS/cm, stability up to 4.5 V and improved fire safety in comparison to the conventional liquid electrolyte (1M LiPF6 in EC/DEC) . Depending on the polymer that is used to build the matrix, the stability could be further improved (1.5-5.0V), which allows stable cycling with high energy density NMC622 cathodes . Furthermore, insights into the DES-polymer interaction allow to optimize the conductivity from 0.4 mS/cm to 1 mS/cm at 25°C .
Second, turning to sodium ion batteries, the silica matrix was organically modified with phenyl groups in ionogels, which reduces the Young’s modulus from 29 to 6 MPa. This improves the charge transfer resistance in Na/Na2Ti3O7 half cells, but also decreases the ionic conductivity somewhat to 3 mS/cm; the anodic stability was 3.9V vs. Na+/Na . The reason that the latter material was an ionogel, was that to the best of our knowledge, at the time there wasn’t any suitable sodium ion conducting DES available in literature. Therefore, its development became the subject of our research as well. A first DES consists of NaTFSI and NMA, demonstrating that high concentrations of salt are needed to improve the electrochemical (up to 4.65 V) and fire hazard stability, while compromising the conductivity, which for the most stable electrolyte is 0.3 mS/cm at 20°C . A remaining issue for this DES is that even the highest concentrated one is not stable in contact with Na metal. This is tackled by a novel composition, with optimized sodium metal compatibility and anodic stability up to 4.0 V vs. Na+/Na, and half cells with cycle life and coulombic efficiency on par with cells built with conventional carbonate-based electrolytes . The development of these novel Na+ conducting DES, paves the way to their incorporation into a solid matrix towards the formation of Na+ ion conducting eutectogels .
In summary, in this presentation an overview of the group’s work of the past 5 years will be given, to show that quite a distance has been travelled on the road from ionic liquids to deep eutectic solvents as liquid electrolytes for sodium ion batteries, and from ionogels to eutectogels in both lithium ion batteries and sodium ion batteries. This has allowed to achieve improvements in cell performance regarding energy density, stability, safety and compatibility with metal anodes
Increasing elasticity of silica-based ionogel electrolytes for sodium-ion batteries: a property study
No full textBatteries are a major base for today’s society and will play an even larger role due to the further electrification. Besides increasing their energy and power density, several challenges exist for the next generation batteries such as designing more sustainable and safer batteries. In this regard, solid-state electrolytes are of high importance because of their higher stability. In this poster, silica-based ionogels for sodium-ion batteries (SIBs) are investigated. SIBs are considered more sustainable than their lithium counterparts due to the high abundance of sodium in the earth’s crust. On the other hand, the quasi-solid silica-based ionogels are very attractive due to their desired electrolyte properties such as high thermal stability, high electrochemical stability, and high ionic conductivity. Unfortunately, silica-based ionogels are in general brittle, which may induce cracking when in contact with electrodes. In this poster silica-based ionogels are organically modified to investigate the effect on the desired electrolyte properties
Mastering electrolyte properties and compatibility: organically modified ionogels for sodium-ion batteries
No full textSilica-based ionogels based on sol-gel synthesis are widely investigated to serve as solid electrolytes for sodium-ion batteries (SIBs). SIBs are more sustainable than lithium-ion batteries (LIBs) due to the high abundance of sodium. Ionogels, in which an ionic liquid electrolyte (ILE) is confined within a silica matrix, are attractive potential solid electrolytes because of their high ionic conductivity, thermal stability, and broad electrochemical window. 1 However, brittleness of such ionogels may adversely affect the performance of the final battery. Increasing the content of ionic liquid has been reported to improve the mechanical properties. 2-3 However, as the ionic liquid is an important cost factor of ionogels, due to the lack of a scalable synthesis, the content of ionic liquid should preferentially remain low. 4 Additionally, increasing the ILE content in silica-based ionogels synthesized through a non-aqueous process only results in a limited mechanical improvement. Therefore, it remains crucial to make further improvements based on organic modifications. It was hypothesized that this would allow lowering of the rigidity of the silica matrix by preventing full condensation due to the presence of an unreactive organic group attached to Si, whilst maintaining the electrochemical properties. A non-aqueous sol-gel route with formic acid (FA) is used to obtain monolithic organically modified ionogels which are homogeneous, transparent, and depending on the phenyl content compliant. The hardness and storage modulus (nano-indentation) were improved upon organic modification whilst a slight reduction of ionic conductivity (electrochemical impedance spectroscopy, EIS) could be noticed as well. Besides, thermal stability (thermogravimetric analysis, TGA), chemical interactions (ATR-FTIR), and anodic stability (linear scanning voltammetry, LSV) were studied as well. These organically modified ionogels are finally researched in SIB full cells to demonstrate their performance as solid electrolyte and the cell's stability. Figure 1: Graphical abstract of organically modified ionogels Acknowledgment
Electrolytes for lithium and sodium ion batteries: the road from ionic liquids to deep eutectic solvents and from solid ionogels to eutectogels.
No full textElectrolytes for lithium and sodium ion batteries: the road from ionic liquids to deep eutectic solvents and from solid ionogels to eutectogels.
An Hardy, Jonas Mercken, An-Sofie Kelchtermans, Bjorn Joos, Dries De Sloovere, Marlies K. Van Bael
In order to increase the energy density as well as the safety of alkali ion batteries, efforts over the past years have focused on solid electrolytes, mainly for Li+ conduction. Among these, the solid composite electrolyte (SCE) consists of a liquid immobilized in a solid skeleton, for example the ionogel which confines an ionic liquid within an inorganic or hybrid solid matrix.
Since deep eutectic solvents have advantages over ionic liquids, such as ease of preparation, cost etc. we proposed a eutectogel (ETG) for lithium ion batteries composed of a DES (LiTFSI/NMA) in a solid silica matrix with a high ionic conductivity of 1.46 mS/cm, high thermal (130°C) and electrochemical stability (up to 4.8V) . However, these materials also are brittle, which in the final cell will influence the interfacial resistance as the contact with the electrode may be limited, besides cracking, limiting the cell performance. Therefore, two strategies were followed for improvement.
First, the silica matrix was replaced by a polymer matrix, called the P-ETG, achieving 0.78 mS/cm, stability up to 4.5 V and improved fire safety in comparison to the conventional liquid electrolyte (1M LiPF6 in EC/DEC) . Depending on the polymer that is used to build the matrix, the stability could be further improved (1.5-5.0V), which allows stable cycling with high energy density NMC622 cathodes . Furthermore, insights into the DES-polymer interaction allow to optimize the conductivity from 0.4 mS/cm to 1 mS/cm at 25°C .
Second, turning to sodium ion batteries, the silica matrix was organically modified with phenyl groups in ionogels, which reduces the Young’s modulus from 29 to 6 MPa. This improves the charge transfer resistance in Na/Na2Ti3O7 half cells, but also decreases the ionic conductivity somewhat to 3 mS/cm; the anodic stability was 3.9V vs. Na+/Na . The reason that the latter material was an ionogel, was that to the best of our knowledge, at the time there wasn’t any suitable sodium ion conducting DES available in literature. Therefore, its development became the subject of our research as well. A first DES consists of NaTFSI and NMA, demonstrating that high concentrations of salt are needed to improve the electrochemical (up to 4.65 V) and fire hazard stability, while compromising the conductivity, which for the most stable electrolyte is 0.3 mS/cm at 20°C . A remaining issue for this DES is that even the highest concentrated one is not stable in contact with Na metal. This is tackled by a novel composition, with optimized sodium metal compatibility and anodic stability up to 4.0 V vs. Na+/Na, and half cells with cycle life and coulombic efficiency on par with cells built with conventional carbonate-based electrolytes . The development of these novel Na+ conducting DES, paves the way to their incorporation into a solid matrix towards the formation of Na+ ion conducting eutectogels .
In summary, in this presentation an overview of the group’s work of the past 5 years will be given, to show that quite a distance has been travelled on the road from ionic liquids to deep eutectic solvents as liquid electrolytes for sodium ion batteries, and from ionogels to eutectogels in both lithium ion batteries and sodium ion batteries. This has allowed to achieve improvements in cell performance regarding energy density, stability, safety and compatibility with metal anodes
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