| 1. |
- Asfaw, Habtom Desta, Dr. 1986-, et al.
(författare)
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Tailoring the Microstructure and Electrochemical Performance of 3D Microbattery Electrodes Based on Carbon Foams
- 2019
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Ingår i: Energy Technology. - : Wiley. - 2194-4288 .- 2194-4296.
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Tidskriftsartikel (refereegranskat)abstract
- Three-dimensional (3D) carbon electrodes with suitable microstructural features and stable electrochemical performance are required for practical applications in 3D lithium (Li)-ion batteries. Herein, the optimization of the microstructures and electrochemical performances of carbon electrodes derived from emulsion-templated polymer foams are dealt with. Exploiting the rheological properties of the emulsion precursors, carbon foams with variable void sizes and specific surface areas are obtained. Carbon foams with an average void size of around 3.8 mu m are produced, and improvements are observed both in the coulombic efficiency and the cyclability of the carbon foam electrodes synthesized at 2200 degrees C. A stable areal capacity of up to 1.22 mAh cm(-2) (108 mAh g(-1)) is achieved at a current density of 50 mu A cm(-2). In addition, the areal capacity remains almost unaltered, i.e., 1.03 mAh cm(-2) (91 mAh g(-1)), although the cycling current density increases to 500 mu A cm(-2) indicating that the materials are promising for power demanding applications.
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| 2. |
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| 3. |
- Kotronia, Antonia, et al.
(författare)
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Catalytically graphitized freestanding carbon foams for 3D Li-ion microbatteries
- 2020
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Ingår i: Journal of Power Sources Advances. - : Elsevier BV. - 2666-2485. ; 1
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Tidskriftsartikel (refereegranskat)abstract
- A long-range graphitic ordering in carbon anodes is desirable since it facilitates Li+ transport within the structure and minimizes irreversible capacity loss. This is of vital concern in porous carbon electrodes that exhibit high surface areas and porosity, and are used in 3D microbatteries. To date, it remains a challenge to graphitize carbon structures with extensive microporosity, since the two properties are considered to be mutually exclusive. In this article, carbon foams with enhanced graphitic ordering are successfully synthesized, while maintaining their bicontinuous porous microstructures. The carbon foams are synthesized from high internal phase emulsion-templated polymers, carbonized at 1000 °C and subsequently graphitized at 2200 °C. The key to enhancing the graphitization of the bespoke carbon foams is the incorporation of Ca- and Mg-based salts at early stages in the synthesis. The carbon foams graphitized in the presence of these salts exhibit higher gravimetric capacities when cycled at a specific current of 10 mA g−1 (140 mAh g−1) compared to a reference foam (105 mAh g−1), which amounts to 33% increase.
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| 4. |
- Kotronia, Antonia, et al.
(författare)
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Nature of the Cathode–Electrolyte Interface in Highly Concentrated Electrolytes Used in Graphite Dual-Ion Batteries
- 2021
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Ingår i: ACS Applied Materials and Interfaces. - : American Chemical Society (ACS). - 1944-8244 .- 1944-8252. ; 13:3, s. 3867-3880
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Tidskriftsartikel (refereegranskat)abstract
- Dual-ion batteries (DIBs) generally operate beyond 4.7 V vs Li+/Li0 and rely on the intercalation of both cations and anions in graphite electrodes. Major challenges facing the development of DIBs are linked to electrolyte decomposition at the cathode–electrolyte interface (CEI), graphite exfoliation, and corrosion of Al current collectors. In this work, X-ray photoelectron spectroscopy (XPS) is employed to gain a broad understanding of the nature and dynamics of the CEI built on anion-intercalated graphite cycled both in highly concentrated electrolytes (HCEs) of common lithium salts (LiPF6, LiFSI, and LiTFSI) in carbonate solvents and in a typical ionic liquid. Though Al metal current collectors were adequately stable in all HCEs, the Coulombic efficiency was substantially higher for HCEs based on LiFSI and LiTFSI salts. Specific capacities ranging from 80 to 100 mAh g–1 were achieved with a Coulombic efficiency above 90% over extended cycling, but cells with LiPF6-based electrolytes were characterized by <70% Coulombic efficiency and specific capacities of merely ca. 60 mAh g–1. The poor performance in LiPF6-containing electrolytes is indicative of the continual buildup of decomposition products at the interface due to oxidation, forming a thick interfacial layer rich in LixPFy, POxFy, LixPOyFz, and organic carbonates as evidenced by XPS. In contrast, insights from XPS analyses suggested that anion intercalation and deintercalation processes in the range from 3 to 5.1 V give rise to scant or extremely thin surface layers on graphite electrodes cycled in LiFSI- and LiTFSI-containing HCEs, even allowing for probing anions intercalated in the near-surface bulk. In addition, ex situ Raman, SEM and TEM characterizations revealed the presence of a thick coating on graphite particles cycled in LiPF6-based electrolytes regardless of salt concentration, while hardly any surface film was observed in the case of concentrated LiFSI and LiTFSI electrolytes.
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| 5. |
- Li, Shaowen, et al.
(författare)
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A Multiscale, Dynamic Elucidation of Li Solubility in the Alloy and Metallic Plating Process
- 2023
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Ingår i: Advanced Materials. - : Wiley-VCH Verlagsgesellschaft. - 0935-9648 .- 1521-4095. ; 35:47
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Tidskriftsartikel (refereegranskat)abstract
- Li-containing alloys and metallic deposits offer substantial Li+ storage capacities as alternative anodes to commercial graphite. However, the thermodynamically in sequence, yet kinetically competitive mechanism between Li solubility in the solid solution and intermediate alloy-induced Li deposition remains debated, particularly across the multiple scales. The elucidation of the mechanism is rather challenging due to the dynamic alloy evolution upon the non-equilibrium, transient lithiation processes under coupled physical fields. Here, influential factors governing Li solubility in the Li-Zn alloy are comprehensively investigated as a demonstrative model, spanning from the bulk electrolyte solution to the ion diffusion within the electrode. Through real-time phase tracking and spatial distribution analysis of intermediate alloy/Li metallic species at varied temperatures, current densities and particle sizes, the driving force of Li solubility and metallic plating along the Li migration pathway are probed in-depth. This study investigates the correlation between kinetics (pronounced concentration polarization, miscibility gap in lattice grains) and rate-limiting interfacial charge transfer thermodynamics in dedicating the Li diffusion into the solid solution. Additionally, the lithiophilic alloy sites with the balanced diffusion barrier and Li adsorption energy are explored to favor the homogeneous metal plating, which provides new insights for the rational innovation of high-capacity alloy/metallic anodes.
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| 6. |
- Ma, Yue, et al.
(författare)
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Multiscale Interfacial Strategy to Engineer Mixed Metal-Oxide Anodes toward Enhanced Cycling Efficiency
- 2018
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Ingår i: ACS Applied Materials and Interfaces. - : American Chemical Society (ACS). - 1944-8244 .- 1944-8252. ; 10:23, s. 20095-20105
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Tidskriftsartikel (refereegranskat)abstract
- Interconnected macro/mesoporous structures of mixed metal oxide (MMO) are developed on nickel foam as freestanding anodes for Li-ion batteries. The sustainable production is realized via a wet chemical etching process with bio-friendly chemicals. By means of divalent iron doping during an in situ recrystallization process, the as-developed MMO anodes exhibit enhanced levels of cycling efficiency. Furthermore, this atomic-scale modification coherently synergizes with the encapsulation layer across a micrometer scale. During this step, we develop a quasi-gel-state tri-copolymer, i.e., F127-resorcinol-melamine, as the N-doped carbon source to regulate the interfacial chemistry of the MMO electrodes. Electrochemical tests of the modified FexN1-xO@NC-NiF anode in both half-cell and full-cell configurations unravel the favorable suppression of the irreversible capacity loss and satisfactory cyclability at the high rates. This study highlights a proof-of-concept modification strategy across multiple scales to govern the interfacial chemical process of the electrodes toward better reversibility.
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| 7. |
- Renman, Viktor, et al.
(författare)
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Manganese pyrosilicates as novel positive electrode materials for Na-ion batteries
- 2018
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Ingår i: Sustainable Energy & Fuels. - : Royal Society of Chemistry (RSC). - 2398-4902. ; 2:5, s. 941-945
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Tidskriftsartikel (refereegranskat)abstract
- A carbon-coated pyrosilicate, Na2Mn2Si2O7/C, was synthesized and characterized for use as a new positive-electrode material for sodium ion batteries. The material consists of 20-80 nm primary particles embedded in a approximate to 10 nm-thick conductive carbon matrix. Reversible insertion of Na+ ions is clearly demonstrated with approximate to 25% of its theoretical capacity (165 mA h g(-1)) being accessible at room temperature at a low cycling rate. The material yields an average potential of 3.3 V vs. Na+/Na on charge and 2.2 V on discharge. DFT calculations predict an equilibrium potential for Na2Mn2Si2O7 in the range of 2.8-3.0 V vs. Na+/Na, with a possibility of a complete flip in the connectivity of neighboring Mn-polyhedra - from edge-sharing to disconnected and vice versa. This significant rearrangement in Mn coordination (approximate to 2 angstrom) and large volume contraction (>10%) could explain our inability to fully desodiate the material, and illustrates well the need for a new electrode design strategy beyond the conventional down-sizing/coating procedure.
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| 8. |
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