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Ferry, Anders
Publications (5 of 5) Show all publications
Edman, L., Ferry, A. & Orädd, G. (2002). Analysis of diffusion in a solid polymer electrolyte in the context of a phase-separated system. Physical Review E 65, 042803 (4), 1-4
Open this publication in new window or tab >>Analysis of diffusion in a solid polymer electrolyte in the context of a phase-separated system
2002 (English)In: Physical Review E 65, 042803, no 4, p. 1-4Article in journal (Refereed) Published
Abstract [en]

The salt and ionic diffusion coefficients of the salt LiN(CF3SO2)2 (LiTFSI) dissolved in high-molecular-weight poly(ethylene oxide) [PEO] have been measured over a broad concentration range, and the interrelationship of the measured values is demonstrated to be in good agreement with basic electrochemical theory. In the light of recently published structural findings, we propose a biphasic model for the conducting amorphous state, consisting of a stoichiometric P(EO)6LiTFSI phase dispersed into a salt-containing disordered phase, and analyze the ionic diffusion data within the framework of the Bruggeman-Landauer theory. The agreement between experimental and fitted data is shown to be excellent. We conclude by pointing out and discussing potential weaknesses of our analysis.

Identifiers
urn:nbn:se:umu:diva-8725 (URN)doi:10.1103/PhysRevE.65.042803 (DOI)
Available from: 2008-02-07 Created: 2008-02-07 Last updated: 2018-06-09Bibliographically approved
Orädd, G., Edman, L. & Ferry, A. (2002). Diffusion: a comparison between liquid and solid polymer LiTFSI electrolytes. Solid State Ionics, 152-153, 131-6
Open this publication in new window or tab >>Diffusion: a comparison between liquid and solid polymer LiTFSI electrolytes
2002 (English)In: Solid State Ionics, Vol. 152-153, p. 131-6Article in journal (Refereed) Published
Abstract [en]

From careful analyses of pfg-NMR data, it is demonstrated that the size of the diffusing Li+·xH2O complex in an aqueous solution of LiTFSI is strongly dependent on salt concentration, with the number of solvating water units ranging from six in dilute (H2O)500LiTFSI to two in highly concentrated (H2O)5LiTFSI. Such a relationship is explained by a mass tendency toward a lower solvation number as the number of available H2O molecules per lithium ion decreases. In a liquid (PEO)nLiTFSI system, a contrasting situation prevails, since the size of the diffusing Li+ complex is almost constant over a large salt concentration range (5≤n≤50). Our interpretations of these data imply that one PEO chain, containing on average nine ether oxygen units, is able to dissolve up to two lithium ions, but exclude the possibility of cationic crosslinks between different PEO chains and direct ionic interactions. For solid P(EO)nLiTFSI eletrolytes, a significantly lower value for the diffusion coefficient of the small lithium ions as compared to that of the large TFSI ions (DLi=0.2DTFSI) was found for all salt concentrations investigated (5≤n≤50). This observation fits in with recent structural observations, which suggest that lithium ions move as single entities in this specific system and require a rather complicated solvation–desolvation step for long-range motion. In all electrolytes investigated, both liquid and solid, the large and bulky TFSI ion appears to be moving as a single unit, thus manifesting the excellent ionization properties of the LiTFSI salt.

Keywords
Solid polymer electrolyte, Liquid electrolyte, PEO, H2O, LiTFSI, Ionic self-diffusion, pfg-NMR
Identifiers
urn:nbn:se:umu:diva-10024 (URN)doi:10.1016/S0167-2738(02)00364-8 (DOI)
Note
Presenterad på följande konferens: 13th International Conference on Solid State Ionics (8-14 July 2001), Cairns, AUSTRALIAAvailable from: 2008-06-11 Created: 2008-06-11 Last updated: 2018-06-09Bibliographically approved
Orädd, G., Edman, L. & Ferry, A. (2001). Diffusion: a comparision between liquid and solid polymer LiTFSI electrolytes. In: 13th International Conference on Solid State Ionics (8-14 July 2001), Cairns, AUSTRALIA.
Open this publication in new window or tab >>Diffusion: a comparision between liquid and solid polymer LiTFSI electrolytes
2001 (English)In: 13th International Conference on Solid State Ionics (8-14 July 2001), Cairns, AUSTRALIA, 2001Conference paper, Published paper (Refereed)
Abstract [en]

From careful analyses of pfg-NMR data, it is demonstrated that the size of the diffusing Li+·xH2O complex in an aqueous solution of LiTFSI is strongly dependent on salt concentration, with the number of solvating water units ranging from six in dilute (H2O)500LiTFSI to two in highly concentrated (H2O)5LiTFSI. Such a relationship is explained by a mass tendency toward a lower solvation number as the number of available H2O molecules per lithium ion decreases. In a liquid (PEO)nLiTFSI system, a contrasting situation prevails, since the size of the diffusing Li+ complex is almost constant over a large salt concentration range (5≤n≤50). Our interpretations of these data imply that one PEO chain, containing on average nine ether oxygen units, is able to dissolve up to two lithium ions, but exclude the possibility of cationic crosslinks between different PEO chains and direct ionic interactions. For solid P(EO)nLiTFSI eletrolytes, a significantly lower value for the diffusion coefficient of the small lithium ions as compared to that of the large TFSI ions (DLi=0.2DTFSI) was found for all salt concentrations investigated (5≤n≤50). This observation fits in with recent structural observations, which suggest that lithium ions move as single entities in this specific system and require a rather complicated solvation–desolvation step for long-range motion. In all electrolytes investigated, both liquid and solid, the large and bulky TFSI ion appears to be moving as a single unit, thus manifesting the excellent ionization properties of the LiTFSI salt.

Keywords
Solid polymer electrolyte, Liquid electrolyte, PEO, H2O, LiTFSI, Ionic self-diffusion, pfg-NMR
Identifiers
urn:nbn:se:umu:diva-10027 (URN)doi:10.1016/S0167-2738(02)00364-8 (DOI)
Note
Solid State Ionics 2002, volumes 152-153, pages 131-6Available from: 2008-06-11 Created: 2008-06-11 Last updated: 2018-06-09Bibliographically approved
Orädd, G., Furlani, M. & Ferry, A. (2000). Diffusion and dielectric studies of the system PPO4000–NH4CF3SO3. Solid State Ionics, 136-7, 457-61
Open this publication in new window or tab >>Diffusion and dielectric studies of the system PPO4000–NH4CF3SO3
2000 (English)In: Solid State Ionics, Vol. 136-7, p. 457-61Article in journal (Refereed) Published
Abstract [en]

A polymer electrolyte system composed of poly(propylene oxide) of molecular weight 4000 (PPO4000) complexed with NH4CF3SO3 (NH4TF) has been investigated by multinuclear pfg-NMR and AC impedance methods. Samples in the concentration range 0.03–0.69 mol/kg (O:NH4 ratios of 500:1–22:1) have been investigated over the temperature range 25–75°C. The combination of AC conductance and pfg-NMR diffusion measurements gives clear evidence that extensive ion-aggregation/clustering occurs at low salt concentrations. With increasing salt-content the Haven ratio, defined as Λcalc/Λexp, decreases from >100 to 2 when going from 0.03 to 0.69 mol/kg. Such gross deviations from the Nernst–Einstein relation (i.e. Λ ∝ D++D−) originate in extensively correlated motions of ions. We interpret the results in terms of labile salt-rich sub-domains being further destabilized through an increase in the dielectric constant of the solution with increasing salt content.

Keywords
Pfg-NMR, Diffusion, AC conductance
Identifiers
urn:nbn:se:umu:diva-10023 (URN)doi:10.1016/S0167-2738(00)00563-4 (DOI)
Note
Presenterad på följande konferens: International Conference(12th) on Solid State Ionics Held in Kassandra, Halkidiki Thessaloniki, Greece on June 6-12, 1999Available from: 2008-06-11 Created: 2008-06-11 Last updated: 2018-06-09Bibliographically approved
Orädd, G., Furlani, M. & Ferry, A. (1999). Diffusion and dielectric studies of the system PPO4000–NH4CF3SO3. In: International Conference(12th) on Solid State Ionics Held in Kassandra, Halkidiki Thessaloniki, Greece on June 6-12, 1999.
Open this publication in new window or tab >>Diffusion and dielectric studies of the system PPO4000–NH4CF3SO3
1999 (English)In: International Conference(12th) on Solid State Ionics Held in Kassandra, Halkidiki Thessaloniki, Greece on June 6-12, 1999, 1999Conference paper, Published paper (Refereed)
Abstract [en]

A polymer electrolyte system composed of poly(propylene oxide) of molecular weight 4000 (PPO4000) complexed with NH4CF3SO3 (NH4TF) has been investigated by multinuclear pfg-NMR and AC impedance methods. Samples in the concentration range 0.03–0.69 mol/kg (O:NH4 ratios of 500:1–22:1) have been investigated over the temperature range 25–75°C. The combination of AC conductance and pfg-NMR diffusion measurements gives clear evidence that extensive ion-aggregation/clustering occurs at low salt concentrations. With increasing salt-content the Haven ratio, defined as Λcalc/Λexp, decreases from >100 to 2 when going from 0.03 to 0.69 mol/kg. Such gross deviations from the Nernst–Einstein relation (i.e. Λ ∝ D++D−) originate in extensively correlated motions of ions. We interpret the results in terms of labile salt-rich sub-domains being further destabilized through an increase in the dielectric constant of the solution with increasing salt content.

Keywords
Pfg-NMR, Diffusion, AC conductance
Identifiers
urn:nbn:se:umu:diva-10025 (URN)doi:10.1016/S0167-2738(00)00563-4 (DOI)
Note
Solid State Ionics 2000, volumes 136-137, pages 457-61Available from: 2008-06-11 Created: 2008-06-11 Last updated: 2018-06-09Bibliographically approved
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