| 1. |
- Anikina, E. V., et al.
(författare)
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Influence of Kubas-type interaction of B–Ni codoped graphdiyne with hydrogen molecules on desorption temperature and storage efficiency
- 2020
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Ingår i: Materials Today Energy. - : Elsevier. - 2468-6069. ; 16
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Tidskriftsartikel (refereegranskat)abstract
- We have investigated functionalized 2D carbon allotrope, graphdiyne (GDY), as a promising hydrogen storage media. Density functional theory with a range of vdW corrections was employed to study Ni decoration of pristine and boron-doped GDY and the interaction of resulting structures with molecular hydrogen. We showed that boron-doped GDY is thermally stable at 300 K, though, its synthesis requires an endothermic reaction. Also, boron doping enhances Ni binding with the graphdiyne by increasing the charge transfer from Ni to GDY. Ni doping drastically influenced hydrogen adsorption energies: they rise from ~70 meV per H2 molecule on pristine GDY to a maximum of 1.29 eV per H2 becoming too high in value for room temperature reversible applications. Boron doping improves the situations: in this case, after Ni decoration desorption temperature estimation is ~300–500 K. Overall, each Ni adatom on B-doped GDY can bind only one H2 molecule within the needed energy range, which gives low hydrogen uptake (~1.2 wt%). However, doping with boron led to the decrease in the value of hydrogen adsorption energy and good desorption temperature estimations, therefore, codoping of metal atoms and boron could be an effective strategy for other transition metals.
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| 2. |
- Asfaw, Habtom Desta, Dr. 1986-, et al.
(författare)
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Facile synthesis of hard carbon microspheres from polyphenols for sodium-ion batteries : insight into local structure and interfacial kinetics
- 2020
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Ingår i: Materials Today Energy. - : Elsevier BV. - 2468-6069. ; 18
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Tidskriftsartikel (refereegranskat)abstract
- Hard carbons are the most promising negative active materials for sodium ion storage. In this work, a simple synthesis approach is proposed to produce hard carbon microspheres (CMSs) (with a mean diameter of ~1.3 μm) from resorcinol-formaldehyde precursors produced via acid-catalyzed polycondensation reaction. Samples prepared at 1200, 1400, and 1500 oC showed different electrochemical behavior in terms of reversible capacity, initial coulombic efficiency (iCE), and the mechanism of sodium ion storage. The specific capacity contributions from the flat voltage profile (<0.1 V) and the sloping voltage region (0.1–1 V) showed strong correlation to the local structure (and carbonization temperature) determined by the interlayer spacing (d002) and the Raman ID/IG ratio of the hard carbons (HCs) and the rate of cycling. Electrochemical tests indicated that the HC synthesized at 1500 oC performed best with an iCE of 85–89% and a reversible capacity of 300–340 mAh g−1 at 10 mA g−1, with the majority of charge stored below 0.1 V. The d002 and the ID/IG ratio for the sample were ~3.7 Å and ~1.27, respectively, parameters indicative of the ideal local structure in HCs required for optimum performance in sodium-ion cells. In addition, galvanostatic tests on three-electrode half-cells cells revealed that sodium metal plating occurred as cycling rates were increased beyond 80 mA g−1 leading to considerably high capacity and poor coulombic efficiency, a point that must be considered in full-cell batteries. Pairing the hard CMS electrodes with Prussian white positive electrode, a proof-of-concept cell could provide a specific capacity of almost 100 mAh g−1 maintained for more than 50 cycles with a nominal voltage of 3 V.
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| 3. |
- Camut, J., et al.
(författare)
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Aluminum as promising electrode for Mg-2(Si,Sn)-based thermoelectric devices
- 2021
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Ingår i: Materials Today Energy. - : Elsevier. - 2468-6069. ; 21
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Tidskriftsartikel (refereegranskat)abstract
- The solid solutions of magnesium silicide and magnesium stannide Mg-2(Si,Sn) are high-performance thermoelectric (TE) materials with the advantage of being composed of light, cheap, and abundant elements. Therefore, they are especially attractive for the conversion of remnant heat into electricity in fields like the automotive sector or the aerospace industry. The optimization of Mg-2(Si,Sn)-based thermoelectric generators requires establishing a suitable electrode to ensure unhindered conduction of the electrical current through the module. We have tested aluminum for such applications and developed a technological process for joining. The obtained functionalized TE legs showed electrical contact resistances below 10 mu Omega cm(2) for both p-and n-type materials and the values are preserved or even lowered with annealing. The p-type material is found to be stable and in the n-type, there is no indication for a charge carrier compensation due to the electrode, as was previously reported e.g. for Cu and Ag. Comparison with other reported electrodes shows that aluminum is so far the most suitable electrode for an Mg-2(Si,Sn)-based module.
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| 4. |
- Etman, Ahmed S., 1986-, et al.
(författare)
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Mo1.33CTz-Ti3C2Tz mixed MXene freestanding films for zinc-ion hybrid supercapacitors
- 2021
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Ingår i: Materials Today Energy. - : Elsevier. - 2468-6069. ; 22
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Tidskriftsartikel (refereegranskat)abstract
- The high demand on fast rechargeable batteries and supercapacitors combined with the limited resources of their active materials (e.g. Li and Co) motivate the exploration of sustainable energy storage systems such as Zn-ion hybrid supercapacitors. MXenes are two-dimensional materials with outstanding properties such as high conductivity and capacitance which enhance their performance in energy storage devices. Herein, we report on the use of freestanding Mo1.33CTz–Ti3C2Tz mixed MXene films in Zn-ion hybrid supercapacitors. The mixed MXene films are prepared from pristine MXene suspensions using a one-step vacuum filtration approach. The mixed MXene delivers capacities of about 159 and 59 mAh/g at scan rates of 0.5 and 100 mV/s, respectively. These capacity values are higher than the pristine MXene films and previously reported values for MXene electrodes in Zn-ion supercapacitors. Furthermore, the electrodes offer a promising capacity retention of about 90% after 8,000 cycles. In addition, the mixed MXene features energy densities of about 103 and 38 Wh/kg at power densities of 0.143 and 10.6 kW/kg, respectively. Insights into the effect of electrode thickness on rate performance and the mechanism of charge storage are also discussed. This study opens a venue for the use of Mo1.33CTz–Ti3C2Tz mixed MXene electrodes in sustainable energy storage systems with high energy density and power density.
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| 5. |
- Hernández, Guiomar, et al.
(författare)
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Polyimide-polyether bindersediminishing the carbon content in lithium-sulfur batteries
- 2017
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Ingår i: Materials Today Energy. - : Elsevier BV. - 2468-6069. ; 6, s. 264-270
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Tidskriftsartikel (refereegranskat)abstract
- Lithium-sulfur batteries are on the run to become the next generation energy storage technology. First of all due to its high theoretical energy density but also for its sustainability and low cost. However, there are still several challenges to take into account such as reducing the shuttle effect, decreasing the amount of conductive carbon to increase the energy density or enhancing the sulfur utilization. Herein, redox-active binders based on polyimide-polyether copolymers have been proposed as a solution to those drawbacks. These multiblock copolymers combine the ability of poly (ethylene oxide) to act as polysulfide trap and the properties of the imide groups to redox mediate the charge-discharge of sulfur. Thus, poly (ethylene oxide) block helps with the shuttle effect and mass transport in the electrode whereas the polyimide part enhances the charge transfer promoting the sulfur utilization. Sulfur cathodes containing pyromellitic, naphthalene or perylene polyimide-polyether binders featured improved cell performance in comparison with pure PEO binder. Among them, the electrode with naphthalene polyimide-PEO binder showed the best results with an initial capacity of 1300 mA h g(-1) at C/5, low polarization and 70% capacity retention after 30 cycles. Reducing the amount of carbon black in the cathode to 5 wt%, the cell with the redox-active binder was able to deliver 500 mA h g(-1) at C/5 with 78% capacity retention after 20 cycles. Our results demonstrate the possibility to reduce the amount of carbon by introducing polyimide-polyether copolymers as redox-active binders, increasing the sulfur utilization, redox kinetics and stability of the cell. (C) 2017 Elsevier Ltd. All rights reserved.
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| 6. |
- Liu, Jianhua, et al.
(författare)
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Metal nanowire networks : Recent advances and challenges for new generation photovoltaics
- 2019
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Ingår i: Materials Today Energy. - : ELSEVIER SCI LTD. - 2468-6069. ; 13, s. 152-185
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Forskningsöversikt (refereegranskat)abstract
- Transparent conducting electrodes which allow photons passing through and simultaneously transfers the charge carriers are critical for the construction of high-performance photovoltaic cells. Electrodes based on metal oxides, such as indium-doped tin oxide (ITO) or fluorine-doped tin oxide (FTO), may have limited application in new generation flexible solar cells, which employ solution-processed roll-to-roll or ink-printing techniques toward large-area-fabrication approach, due to their brittleness and poor mechanical properties. Metal nanowire network (MNWN) emerges as a highly potential alternative candidate instead of ITO or FTO due to the high transparency, low sheet resistance, low cost, solution processable and compatibility with a flexible substrate for high throughput production. This feature article systematically summarizes the recent advances of the MNWNs, including new concepts and emerging strategies for the synthesis of metal nanowires (MNWs), various approaches for the preparation of MNWNs and comprehensively discusses the novel MNWN electrodes prepared on different substrates. The state-of-the-art new generation solar cell devices, such as transparent, flexible and light-weight solar cells, with MNWN as a transparent conductive electrode are emphasized. Finally, the opportunities and challenges for the development of MNWN electrodes toward application in the new generations of photovoltaic devices are discussed.
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| 7. |
- Mathayan, Vairavel, et al.
(författare)
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Sensitive in-operando observation of Li and O transport in thin-film Li-ion batteries
- 2021
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Ingår i: Materials Today Energy. - : Elsevier. - 2468-6069. ; 21
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Tidskriftsartikel (refereegranskat)abstract
- Thin-film batteries often contain oxides in the anode, cathode, and electrolyte materials. In-operando methods capable of Li and O depth profiling are relevant for battery research to study, e.g. diffusion and trapping of constituents. Here, we demonstrate ion beam-based analytical methods with high depth resolution and sensitivity for depth profiling Li and O in thin-film batteries using 10 MeV Li and He ions. Simultaneous depth profiling of Li and O was performed using combined coincidence elastic recoil detection analysis and Rutherford backscattering spectrometry measurements in the battery with 8 MeV He ions, and the Li and O transport was measured in operando. Reversible Li transport was observed from the LMO anode to the NbO cathode on charging and vice versa during discharging. O transport was observed from the LMO anode to the NbO cathode on first charging with 3.5 V but was not observed on further charging and discharging of the battery. Our in-operando measurements allow direct and quantitative observation of Li and O transport during charge-discharge cycles for thin-film batteries.
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| 8. |
- Mishra, Pushkar, et al.
(författare)
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Bifunctional catalytic activity of 2D boron monochalcogenides BX (X = S, Se, Te)
- 2022
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Ingår i: Materials Today Energy. - : Elsevier. - 2468-6069. ; 27
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Tidskriftsartikel (refereegranskat)abstract
- Photocatalysis and electrocatalysis are two sustainable and renewable technologies that can meet global energy demands in environmentally friendly ways. According to recent research, 2D boron monochalcogenides in the 1 T and 2 H phases are stable, strong, and broad bandgap semiconductors. Our calculations show a strong UV absorption ability and suitable band edge positions for water splitting oxidation and reduction, making it a good choice for an efficient photocatalyst. The development of bifunctional electrocatalysts has piqued the interest of researchers working in the field of electrocatalysts for fuel cells. The electrocatalytic properties of 2D boron monochalcogenides are also investigated for catalyzing both oxygen evolution reaction (OER) and oxygen reduction reaction (ORR). The calculated overpotentials for OER/ORR mechanism are found to be 0.92/1.09 for BS (1 T), 1.00/0.59 for BS (2 H), 0.96/1.05 for BSe (1 T), 0.92/0.85 for BSe (2 H), and 1.10/0.92 for BTe (1 T), which are close to benchmark catalysts. The ORR overpotential of BS (2H) is 0.59 V, near well-known catalyst Pt (0.45 V). Therefore, our investigations indicate that the family of 2D materials, boron monochalcogenides, are promising photocatalyst and electrocatalyst candidates for OER and ORR.
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| 9. |
- Xiong, Shizhao, 1985, et al.
(författare)
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Lithium electrodeposition for energy storage: filling the gap between theory and experiment
- 2022
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Ingår i: Materials Today Energy. - : Elsevier BV. - 2468-6069. ; 28
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Tidskriftsartikel (övrigt vetenskapligt/konstnärligt)abstract
- Lithium (Li) metal has been considered a promising anode material for high-energy-density rechargeable batteries, but its utilization is impeded by the nonuniform electrodeposition during the charging process which leads to poor cycling life and safety concerns. Thus, understanding the electrodeposition mechanism of Li-metal anode is of great importance to develop practical engineering strategies for rechargeable Li-metal batteries. The electrodeposition of Li is controlled by both thermodynamic and kinetic factors, such as the solvation free energy of Li-ions, the Li nucleation, the surface diffusion of Li atom, and the strength of the interaction between Li-ion and the electrolyte anion. The scale of the whole process from the Li-ion reduction to the growth of a Li nucleus goes from sub-nanometer up to a few micrometers, which poses an outstanding challenge to both experiments and simulation. In this perspective, we discuss the top-down, the bottom-up, and the middle-way approaches to this challenge and the possible synergies between them.
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