| 1. |
- Sun, Bing, et al.
(författare)
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Towards Solid-State 3D-Microbatteries using Functionalized Polycarbonate-based Polymer Electrolytes
- 2018
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Ingår i: ACS Applied Materials and Interfaces. - 1944-8244 .- 1944-8252. ; 10:3, s. 2407-2413
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Tidskriftsartikel (refereegranskat)abstract
- 3D-microbatteries (3D-MBs) impose new demands for theselection, fabrication and compatibility of the different battery components, notleast the electrolytes. Herein, solid polymer electrolytes (SPEs) based on poly(trimethylene carbonate) (PTMC) have been implemented in 3D-MB systems. 3D electrodes of two different architectures, LiFePO4-coated carbon foams and Cu2O-coated Cu nanopillars, have been coated with SPEs and used in Li-cells. Functionalized PTMC with hydroxyl end groups was found to enable uniform and well-covering coatings on LiFePO4-coated carbon foams, although the cell cycling performance was limited by the large SPE resistance. By employing a SPE prepared from a copolymer of TMC and caprolactone (CL), with higher ionic conductivity, Li-cells composed of Cu2O-coated Cu nanopillars were constructed and tested both at room temperature and 60 °C. The footprint areal capacity of the cells was ca. 0.02 mAh cm-2 for an area gain factor (AF) of 2.5, and 0.2 mAh cm-2 for a relatively dense nanopillar-array (AF=25) at a current density of 0.008 mA cm-2at ambient temperature (22±1 °C). These results provide new routes towards the realization of all-solid-state 3D-MBs.
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| 2. |
- Klein, Edina, et al.
(författare)
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Elucidating the development of cooperative anode-biofilm-structures
- 2024
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Ingår i: Biofilm. - : Elsevier. - 2590-2075. ; 7
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Tidskriftsartikel (refereegranskat)abstract
- Microbial electrochemical systems are a highly versatile platform technology with a particular focus on the interplay of chemical and electrical energy conversion and offer immense potential for a sustainable bioeconomy. The industrial realization of this potential requires a critical focus on biofilm optimization if performance is to be controlled over a long period of time. Moreover, the aspect and influence of cooperativity has to be addressed as many applied anodic bioelectrochemical systems will most likely be operated with a diversity of interacting microbial species. Hence, the aim of this study was to analyze how interspecies dependence and cooperativity of a model community influence the development of anodic biofilms. To investigate biofilm activity in a spatially resolved manner, a microfluidic bioelectrochemical flow cell was developed that can be equipped with user-defined electrode materials and operates under laminar flow conditions. With this infrastructure, the development of single and co-culture biofilms of the two model organisms Shewanella oneidensis and Geobacter sulfurreducens on graphite electrodes was monitored by optical coherence tomography analysis. The interdependence in the co-culture biofilm was achieved by feeding the community with lactate, which is converted by S. oneidensis into acetate, which in turn serves as substrate for G. sulfurreducens. The results show that co-cultivation resulted in the formation of denser biofilms than in single culture. Moreover, we hypothesize that S. oneidensis in return utilizes the conductive biofilm matrix build by G. sulfurreducens for direct interspecies electron transfer (DIET) to the anode. FISH analysis revealed that the biofilms consisted of approximately two-thirds G. sulfurreducens cells, which most likely formed a conductive 3D network throughout the biofilm matrix, in which evenly distributed tubular S. oneidensis colonies were embedded without direct contact to the anode surface. Live/dead staining shows that the outermost biofilm contained almost exclusively dead cells (98 %), layers near the anode contained 45–56 % and the entire biofilm contained 82 % live cells. Our results exemplify how the architecture of the exoelectrogenic biofilm dynamically adapts to the respective process conditions.
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| 3. |
- Lindgren, Fredrik, et al.
(författare)
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Breaking Down a Complex System : Interpreting PES Peak Positions for Cycled Li-ion Battery Electrodes
- 2017
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Ingår i: The Journal of Physical Chemistry C. - : American Chemical Society (ACS). - 1932-7447 .- 1932-7455. ; 121, s. 27303-27312
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Tidskriftsartikel (refereegranskat)abstract
- Photoelectron spectroscopy (PES) is an important technique for tracing and understanding the side reactions responsible for decreasing performance of Li-ion batteries. Interpretation of different spectral components is dependent on correct binding energy referencing and for battery electrodes this is highly complex. In this work, we investigate the effect on binding energy reference points in PES in correlation to solid electrolyte interphase (SEI) formation, changing electrode potentials and state of charge variations in Li-ion battery electrodes. The results show that components in the SEI have a significantly different binding energy reference point relative to the bulk electrode material (i.e. up to 2 eV). It is also shown that electrode components with electronically insulating/semi-conducting nature are shifted as a function of electrode potential relative to highly conducting materials. Further, spectral changes due to lithiation are highly depending on the nature of the active material and its lithiation mechanism. Finally, a strategy for planning and evaluating PES experiments on battery electrodes is proposed where some materials require careful choice of one or more internal reference points while others may be treated essentially without internal calibration.
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| 4. |
- Lindgren, Fredrik, et al.
(författare)
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On the Capacity Losses Seen for Optimized Nano-Si Composite Electrodes in Li-Metal Half-Cells
- 2019
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Ingår i: Advanced Energy Materials. - : Wiley. - 1614-6832 .- 1614-6840. ; 9:33
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Tidskriftsartikel (refereegranskat)abstract
- While the use of silicon‐based electrodes can increase the capacity of Li‐ion batteries considerably, their application is associated with significant capacity losses. In this work, the influences of solid electrolyte interphase (SEI) formation, volume expansion, and lithium trapping are evaluated for two different electrochemical cycling schemes using lithium‐metal half‐cells containing silicon nanoparticle–based composite electrodes. Lithium trapping, caused by incomplete delithiation, is demonstrated to be the main reason for the capacity loss while SEI formation and dissolution affect the accumulated capacity loss due to a decreased coulombic efficiency. The capacity losses can be explained by the increasing lithium concentration in the electrode causing a decreasing lithiation potential and the lithiation cut‐off limit being reached faster. A lithium‐to‐silicon atomic ratio of 3.28 is found for a silicon electrode after 650 cycles using 1200 mAhg−1 capacity limited cycling. The results further show that the lithiation step is the capacity‐limiting step and that the capacity losses can be minimized by increasing the efficiency of the delithiation step via the inclusion of constant voltage delithiation steps. Lithium trapping due to incomplete delithiation consequently constitutes a very important capacity loss phenomenon for silicon composite electrodes.
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| 5. |
- Liu, Chenjuan, 1988-, et al.
(författare)
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Growth of NaO2 in Highly Efficient Na–O2 Batteries Revealed by Synchrotron In Operando X-ray Diffraction
- 2017
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Ingår i: ACS Energy Letters. - : American Chemical Society (ACS). - 2380-8195. ; 2, s. 2440-2444
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Tidskriftsartikel (övrigt vetenskapligt/konstnärligt)abstract
- The development of Na–O2 batteries requires understanding the formation of reaction products, as different groups reported compounds such as sodium peroxide, sodium superoxide, and hydrated sodium peroxide as the main discharge products. In this study, we used in operando synchrotron radiation powder X-ray diffraction (SR-PXD) to (i) quantitatively track the formation of NaO2 in Na–O2 cells and (ii) measure how the growth of crystalline NaO2 is influenced by the choice of electrolyte salt. The results reveal that the discharge could be divided into two time regions and that the formation of NaO2 during the major part of the discharge reaction is highly efficient. The findings indicate that the cell with NaOTf salt exhibited higher capacity than the cell with NaPF6 salt, whereas the average domain size of NaO2 particles decreases during the discharge. This fundamental insight brings new information on the working mechanism of Na–O2 batteries.
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| 6. |
- Malinovskis, Paulius, et al.
(författare)
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Synthesis and characterization of multicomponent (CrNbTaTiW)C films for increased hardness and corrosion resistance
- 2018
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Ingår i: Materials & design. - : Elsevier BV. - 0264-1275 .- 1873-4197. ; 149, s. 51-62
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Tidskriftsartikel (refereegranskat)abstract
- Multicomponent carbide thin films of (CrNbTaTiW)C (30–40 at.% C) with different metal contents were depos-ited at different temperatures using non-reactive DC magnetron sputtering. The lattice distortion for the metallattice was estimated to vary from about 3 to 5%. Most films crystallized in the cubic B1 structure but Ta/W-rich films deposited at 600 °C exhibited a tetra gonal distortion. X-ray diffraction results sh ow that near-equimolar films exhibited a strong (111) texture. In contrast, Ta/W-rich films exhibited a shift from (111) to(100) texture at 450 °C. The in-plane relationship was determined to MC(111)[-12-1]//Al2O3(001)[110] with alattice mismatch of about 11% along the Al2O3[110] direction. A segregation of Cr to the grain boundaries was ob-served in all films. The microstructure was found to be the most important factor for high hardness. Less denseNb-rich and near-equimolar films deposited at low tem peratures exhib ited the low est hardnes s (12 GPa),while very dense Ta/W-rich high temperature films were found to be the hardest (36 GPa). No correlation wasfound between the lattice distortion and the hardness. Corrosion studies revealed that the multicomponentfilms exhibited excellent corrosion resistance, superior to that of a reference hyper-duplex stainless steel, in1.0 M HCl.
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| 7. |
- Rehnlund, David, 1986-, et al.
(författare)
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Dendrite-free lithium electrode cycling via controlled nucleation in low LiPF6 concentration electrolytes
- 2018
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Ingår i: Materials Today. - : Elsevier BV. - 1369-7021 .- 1873-4103. ; 21:10, s. 1010-1018
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Tidskriftsartikel (refereegranskat)abstract
- Lithium metal electrodes are not widely used in rechargeable batteries as dendritic lithium growth and electrolyte reactions raise serious stability and safety concerns. In this study, we show that reproducible two-dimensional lithium deposition can be realized using a lithium salt concentration of 0.020 M, an added supporting salt, and a short lithium nucleation pulse. This approach, which is common in electrodeposition of metals, increases the lithium nuclei density on the electrode surface and decreases the extent of Li+ migration favoring dendritic lithium growth. Contrary to common belief, ascribing the dendrite problem to heterogeneous lithium nucleation due to an unstable solid electrolyte interphase layer, we show that the main lithium deposition problem stems from the difficulty to obtain two-dimensional deposition at the low lithium deposition overpotentials encountered in conventional high-lithium concentration electrolytes. The present results hence clearly demonstrate that two-dimensional lithium deposition can be realized in lithium-metal-based batteries.
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| 8. |
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| 9. |
- Rehnlund, David, 1986-, et al.
(författare)
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Electrochemical Manufacturing and Characterisation of Nanostructured Electrodes for Lithium based Batteries
- 2018
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Konferensbidrag (övrigt vetenskapligt/konstnärligt)abstract
- Due to their high energy and power densities, lithium-ion batteries are the primary choice for application in consumer electronics. Although new electrode materials for Li-ion batteries are developed continuously, relatively little attention has so far been paid to the use of electrochemical methods in the manufacturing of battery materials. In the field of microbatteries, electrodeposition has, nevertheless, become an important technique for the manufacturing of current collectors, electrode materials and electrolytes [1]. During the last few years it has also been shown that electrochemically nanostructured electrodes lacking binders and other additives can facilitate the attainment of an improved understanding of the electrochemical reactions taking place in lithium based batteries. This presentation will focus on the development of electrochemical approaches for the manufacturing and study of nanostructured electrode materials for lithium based batteries. It will be shown that electrodeposition can be used for the manufacturing of 3-D copper and aluminium [1] current collectors as well as the coating of these with thin layers of anode or cathode materials. Electrochemical manufacturing and characterisation of materials such as multilayered Cu/Cu2O nanorods [2], Sn/SnO2 particles [3] and TiO2 nanotubes (see Figure 1) will be discussed, as well as a new approach for the manufacturing of TiO2 nanotube size gradient based electrodes [4]. Some fundamental issues regarding the electrochemical processes in the electrochemically manufactured materials, including the formation of “cathodic passive layers” and “trapping of lithium” in current collectors and alloy forming electrode materials [5] and the electrodeposition of homogeneous lithium films on lithium electrodes (see Figure 1) will likewise be discussed. References [1] K. Edström, D. Brandell, T. Gustafsson, L. Nyholm, Electrodeposition as a tool for 3D Microbattery Fabrication, Electrochem. Soc. Interface, 20 (2011) 41.[2] D. Rehnlund, M. Valvo, C. –W. Tai, J. Ångström, M. Sahlberg, K. Edström, L. Nyholm, Electrochemical fabrication and characterization of Cu/Cu2O multi-layered micro and nanorods in Li-ion batteries, Nanoscale, 7 (2015) 13591.[3] S. Böhme, K. Edström, L. Nyholm, Overlapping and Rate Controlling Electrochemical Reactions for Tin(IV) Oxide Electrodes in Lithium-Ion Batteries, J. Electroanal. Chem., 797 (2017) 47.[4] W. Wei, F. Björefors, L. Nyholm, Hybrid energy storage devices based on monolithic electrodes containing well-defined TiO2 nanotube size gradients, Electrochim. Acta, 176 (2015) 1393.
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| 10. |
- Rehnlund, David, 1986-
(författare)
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Electrochemically nanostructured electrodes for Li-ion microbatteries
- 2013
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Licentiatavhandling (övrigt vetenskapligt/konstnärligt)abstract
- Electrodeposition is a promising technique for fabricating complex nanostructures and coating these with suitable thin films of active materials. The research presented in this thesis aims at the development of new electro- chemical methods for the synthesis of nanostructured electrodes suitable for Li-ion microbatteries. Electrodes based on nanostructured Cu and Al current collectors have been investigated to provide insight into the fabrication of both anodes and cathodes.Coating 3D aluminium current collectors with a vanadium oxide thin film is generally accompanied by aluminium corrosion due to the oxidative environment employed in the electrodeposition. To circumvent this issue a protective intermediate MnOx coating was implemented which suppresses the Al corrosion thereby facilitating subsequent vanadium oxide deposition.3D Cu electrodes with thin Cu2O coatings were fabricated to investigate their electrochemical properties and the mechanism of the Cu2O conversion reaction. Impressive high-rate cycling capabilities and capacity retention were observed with capacities corresponding to 130% of the theoretical capacity obtained after 390 cycles. This capacity gain was linked to electro- chemical milling of the Cu2O particles producing particles smaller than 5 nm. A distribution of particles with different sizes was also observed during the electrochemical analysis. This gave rise to a substantial redox potential distribution and a large electroactive potential window.
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