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| 3. |
- Böhme, Solveig, et al.
(author)
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Electrochemical behavior of tin(IV) oxide electrodes in lithium-ion batteries at high potentials
- 2015
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Conference paper (other academic/artistic)abstract
- In commercial lithium-ion batteries (LIB) graphite is used as the anode material. However, graphite has a rather limited volumetric and gravimetric capacity which is a drawback when higher energy densities are required as for instance in cars. Here, other materials with higher capacities and energy densities like the alloying materials tin and silicon are hence needed. Even bigger capacities could be obtained using tin oxide based compounds due to a combination of the tin oxide conversion reaction with lithium to tin and lithium oxide and the alloying reaction between tin and lithium. However, tin oxides usually suffer a great capacity loss after the first cycle due to the irreversibility of tin oxide reduction with lithium. [1,2] Nevertheless, there have been some reports in the past about a limited reversibility of the tin(IV) oxide conversion. [3-5]In our work we, therefore, investigated voltammetric cycling of tin(IV) oxide electrodes in different potential windows in order to learn about the influence of the alloying reaction on the conversion reaction (excluding the alloying reaction when cutting at 0.9 V vs. Li+/Li). In addition, rather high voltages (up to 3.7 V vs. Li+/Li) were applied to check the tin(IV) oxide conversion reversibility and electrode stability. Further cycling experiments were carried out at 60 oC and the results compared to cycling at room temperature. Cycling products at different potentials and temperatures were investigated using XPS. The results confirmed a certain reversibility of the tin(IV) oxide conversion which seemed to be enhanced at 60 oC. Cycling at a higher temperature generally lead to bigger capacities of the tin(IV) oxide electrodes. Courtney, I.A. and Dahn, J.R., J. Electrochem. Soc., 1997, 144, 2045-2052.Courtney, I.A.; McKinnon, W.R. and Dahn, J.R., J. Electrochem. Soc., 1999, 146, 59-68.Chouvin, J.; Branci, C.; Sarradin, J.; Olivier-Fourcade, J.; Jumas, J.C.; Simon, B. and Biensan, P., J. Power Sources, 1999, 81-82, 277-281.Chouvin, J.; Olivier-Fourcade, J.; Jumas, J.C.; Simon, B.; Biensan, P.; Fernández Madrigal, F.J.; Tirado, J.L. and Pérez Vicente, C., J. Electroanal. Chem., 2000, 494, 136-146.Sun, X.; Liu, J. and Li, Y., Chem. Mater., 2006, 18, 3486-3494.
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| 4. |
- Böhme, Solveig, et al.
(author)
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Electrochemical behaviour of tin(IV) oxide electrodes in lithium-ion batteries at high potentials
- 2015
-
Conference paper (other academic/artistic)abstract
- In commercial lithium-ion batteries graphite is currently the most common anode material. However, graphite has a rather limited volumetric and gravimetric capacity which is a drawback when higher energy densities are required, for instance, in cars. Here, other materials with higher capacities and energy densities like the alloying materials tin and silicon are, hence, required. Even bigger capacities could be obtained using tin oxide based compounds due to a combination of the tin oxide conversion reaction converting lithium to tin and lithium oxide and the alloying reaction between tin and lithium. However, tin oxides usually suffer a great capacity loss after the first cycle due to the irreversibility of the tin oxide reduction. [1,2] Nevertheless, there have been some reports suggesting a limited reversibility of the tin(IV) oxide conversion. [3-6]In this work we have investigated the voltammetric behaviour of tin(IV) oxide electrodes within different potential windows in order to study the influence of the alloying reaction on the conversion reaction (excluding the alloying reaction by cycling to 0.9 V vs. Li+/Li). In addition, rather high voltages (up to 3.7 V vs. Li+/Li) were applied to check the tin(IV) oxide conversion reversibility as well as electrode and electrolyte stability under these conditions. The results were also compared with those presented in an earlier model study carried with our group. [6] Cycling experiments were likewise carried out at 60oC and these results will be compared to those obtained for cycling at room temperature. The products formed at different potentials and temperatures were investigated using XPS and SEM. The results confirmed the presence of a partial reversibility of the tin(IV) oxide conversion reaction which was enhanced at 60oC. It will be demonstrated that cycling at a higher temperature lead to larger capacities of tin(IV) oxide electrodes. In addition, the influence of different cycling rates on the capacity will be discussed. Courtney, I.A. and Dahn, J.R., J. Electrochem. Soc., 1997, 144, 2045-2052.Courtney, I.A.; McKinnon, W.R. and Dahn, J.R., J. Electrochem. Soc., 1999, 146, 59-68.Chouvin, J.; Branci, C.; Sarradin, J.; Olivier-Fourcade, J.; Jumas, J.C.; Simon, B. and Biensan, P., J. Power Sources, 1999, 81-82, 277-281.Chouvin, J.; Olivier-Fourcade, J.; Jumas, J.C.; Simon, B.; Biensan, P.; Fernández Madrigal, F.J.; Tirado, J.L. and Pérez Vicente, C., J. Electroanal. Chem., 2000, 494, 136-146.Sun, X.; Liu, J. and Li, Y., Chem. Mater., 2006, 18, 3486-3494Böhme, S.; Edström, K. and Nyholm, L., On the electrochemistry of tin oxide coated tin electrodes in lithium-ion batteries, Electrochim. Acta, 2015 (in press).
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| 5. |
- Böhme, Solveig, et al.
(author)
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Electrochemical behaviour of tin(IV) oxide electrodes in lithium-ion batteries at high temperature and potentials
- 2016
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Conference paper (other academic/artistic)abstract
- In commercial lithium-ion batteries graphite is currently the most common anode material. However, graphite has a rather limited volumetric and gravimetric capacity which is a drawback when higher energy densities are required, for instance, in cars. Here, other materials with higher capacities and energy densities like the alloying materials tin and silicon are, hence, required. Even bigger capacities could be obtained using tin oxide based compounds due to a combination of the tin oxide conversion reaction converting lithium to tin and lithium oxide and the alloying reaction between tin and lithium. However, tin oxides usually suffer a great capacity loss after the first cycle due to the irreversibility of the tin oxide reduction.[1,2] Nevertheless, there have been some reports suggesting a limited reversibility of the tin oxide conversion. [3-6] In our work we have investigated the kinetic behaviour of different tin(IV) oxide based electrodes during electrochemical cycling in lithium-ion batteries for both the conversion and the alloying reaction. To be able to study the influence of the alloying reaction on the conversion reaction cycling was carried out within different potential windows (excluding the alloying reaction by cycling only to 0.9 V vs. Li+/Li). In addition, rather high voltages (up to 3.7 V vs. Li+/Li) were applied to check the tin(IV) oxide conversion reversibility as well as electrode and electrolyte stability under these conditions. The results were also compared with those presented in an earlier model study carried with our group. [6] Cycling experiments were likewise carried out at 60 oC as well as different scan rates and with different particle sizes and additives (i.e. aluminium oxide and diamond). The products formed at different potentials and temperatures for tin(IV) oxide electrodes were also investigated using XPS and SEM. The results confirmed the presence of a partial reversibility of the tin(IV) oxide conversion reaction which was enhanced at 60 oC. The study, thus, indicated that there is a kinetic limitation regarding the reoxidation of tin to tin oxide upon charge which can be overcome more easily when using higher temperatures or smaller particles. It will be demonstrated that cycling at a higher temperature, lower scan rate or with a smaller particle size leads to larger capacities of tin(IV) oxide electrodes. In addition, the influence of different additives on the capacity will be discussed. REFERENCESCourtney, I.A. and Dahn, J.R., J. Electrochem. Soc., 1997, 144, 2045-2052.Courtney, I.A.; McKinnon, W.R. and Dahn, J.R., J. Electrochem. Soc., 1999, 146, 59-68.Chouvin, J.; Branci, C.; Sarradin, J.; Olivier-Fourcade, J.; Jumas, J.C.; Simon, B. and Biensan, P., J. Power Sources, 1999, 81-82, 277-281.Chouvin, J.; Olivier-Fourcade, J.; Jumas, J.C.; Simon, B.; Biensan, P.; Fernández Madrigal, F.J.; Tirado, J.L. and Pérez Vicente, C., J. Electroanal. Chem., 2000, 494, 136-146.Sun, X.; Liu, J. and Li, Y., Chem. Mater., 2006, 18, 3486-3494Böhme, S.; Edström, K. and Nyholm, L., On the electrochemistry of tin oxide coated tin electrodes in lithium-ion batteries, Electrochim. Acta, 2015, 179, 482-494.
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| 6. |
- Böhme, Solveig, 1987-, et al.
(author)
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Elevated Temperature Lithium-Ion Batteries Containing SnO2 Electrodes and LiTFSI-Pip14TFSI Ionic Liquid Electrolyte
- 2017
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In: Journal of the Electrochemical Society. - : The Electrochemical Society. - 0013-4651 .- 1945-7111. ; 164:4, s. A701-A708
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Journal article (peer-reviewed)abstract
- The performance of lithium-ion batteries (LIBs) comprising SnO2 electrodes and an ionic liquid (IL) based electrolyte, i.e., 0.5 MLiTFSI in Pip14TFSI, has been studied at room temperature (i.e., 22◦C) and 80◦C. While the high viscosity and low conductivity ofthe electrolyte resulted in high overpotentials and low capacities at room temperature, the SnO2 performance at 80◦C was found to beanalogous to that seen at room temperature using a standard LP40 electrolyte (i.e., 1MLiPF6 dissolved in 1:1 ethylene carbonate anddiethyl carbonate). Significant reduction of the IL was, however, found at 80◦C, which resulted in low coulombic efficiencies duringthe first 20 cycles, most likely due to a growing SEI layer and the formation of soluble IL reduction products. X-ray photoelectronspectroscopy studies of the cycled SnO2 electrodes indicated the presence of an at least 10 nm thick solid electrolyte interphase (SEI)layer composed of inorganic components such as lithium fluoride, sulfates, and nitrides as well as organic species containing C-H,C-F and C-N bonds.
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| 7. |
- Böhme, Solveig, 1987-
(author)
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Fundamental Insights into the Electrochemistry of Tin Oxide in Lithium-Ion Batteries
- 2017
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Doctoral thesis (other academic/artistic)abstract
- This thesis aims to provide insight into the fundamental electrochemical processes taking place when cycling SnO2 in lithium-ion batteries (LIBs). Special attention was paid to the partial reversibility of the tin oxide conversion reaction and how to enhance its reversibility. Another main effort was to pinpoint which limitations play a role in tin based electrodes besides the well-known volume change effect in order to develop new strategies for their improvement. In this aspect, Li+ mass transport within the electrode particles and the large first cycle charge transfer resistance were studied. Li+ diffusion was proven to be an important issue regarding the electrochemical cycling of SnO2. It was also shown that it is the Li+ transport inside the SnO2 particles which represents the largest limitation. In addition, the overlap between the potential regions of the tin oxide conversion and the alloying reaction was investigated with photoelectron spectroscopy (PES) to better understand if and how the reactions influence each other`s reversibility.The fundamental insights described above were subsequently used to develop strategies for the improvement of the performance and the cycle life for SnO2 electrodes in LIBs. For instance, elevated temperature cycling at 60 oC was employed to alleviate the Li+ diffusion limitation effects and, thus, significantly improved capacities could be obtained. Furthermore, an ionic liquid electrolyte was tested as an alternative electrolyte to cycle at higher temperatures than 60 oC which is the thermal stability limit for the conventional LP40 electrolyte. In addition, cycled SnO2 nanoparticles were characterized with transmission electron microscopy (TEM) to determine the effects of long term high temperature cycling. Also, the effect of vinylene carbonate (VC) as an electrolyte additive on the cycling behavior of SnO2 nanoparticles was studied in an effort to improve the capacity retention. In this context, a recently introduced intermittent current interruption (ICI) technique was employed to measure and compare the development of internal cell resistances with and without VC additive.
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| 8. |
- Böhme, Solveig, et al.
(author)
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Lithium-ion batteries based on SnO2 electrodes and a LiTFSI-Pip14TFSI ionic liquid electrolyte
- 2017
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In: Journal of the Electrochemical Society. - : The Electrochemical Society. - 1945-7111 .- 0013-4651. ; 164:4, s. A701-A708
-
Journal article (peer-reviewed)abstract
- The performance of lithium-ion batteries (LIBs) comprising SnO2 electrodes and an ionic liquid (IL) based electrolyte, i.e., 0.5 M LiTFSI in Pip14TFSI, has been studied at room temperature (i.e., 22°C) and 80°C. While the high viscosity and low conductivity of the electrolyte resulted in high overpotentials and low capacities at room temperature, the SnO2 performance at 80°C was found to be analogous to that seen at room temperature using a standard LP40 electrolyte (i.e., 1 M LiPF6 dissolved in 1:1 ethylene carbonate and diethyl carbonate). Significant reduction of the IL was, however, found at 80°C, which resulted in low coulombic efficiencies during the first 20 cycles, most likely due to a growing SEI layer and the formation of soluble IL reduction products. X-ray photoelectron spectroscopy studies of the cycled SnO2 electrodes indicated the presence of an at least 10 nm thick solid electrolyte interphase (SEI) layer composed of inorganic components such as lithium fluoride, sulfates, and nitrides as well as organic species containing C-H, C-F and C-N bonds.
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| 9. |
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| 10. |
- Böhme, Solveig, 1987-, et al.
(author)
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On the electrochemistry of tin oxide coated tin electrodes in lithium-ion batteries
- 2015
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In: Electrochimica Acta. - : Elsevier BV. - 0013-4686 .- 1873-3859. ; 179, s. 482-494
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Journal article (peer-reviewed)abstract
- As tin based electrodes are of significant interest in the development of improved lithium-ion batteries it is important to understand the associated electrochemical reactions. In this work it is shown that the electrochemical behavior of SnO2 coated tin electrodes can be described based on the SnO2 and SnO conversion reactions, the lithium tin alloy formation and the oxidation of tin generating SnF2. The CV, XPS and SEM data, obtained for electrodeposited tin crystals on gold substrates, demonstrates that the capacity loss often observed for SnO2 is caused by the reformed SnO2 layer serving as a passivating layer protecting the remaining tin. Capacities corresponding up to about 80 % of the initial SnO2 capacity could, however, be obtained by cycling to 3.5 V vs. Li+/Li. It is also shown that the oxidation of the lithium tin alloy is hindered by the rate of the diffusion of lithium through a layer of tin with increasing thickness and that the irreversible oxidation of tin to SnF2 at potentials larger than 2.8 V vs. Li+/Li is due to the fact that SnF2 is formed below the SnO2 layer. This improved electrochemical understanding of the SnO2/Sn system should be valuable in the development of tin based electrodes for lithium-ion batteries.
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