Dimethyl Carbonate Table 1: Diffusion constants for EC and DC, calculated from the PFGSE experiment. 19 Electrolyte Solvent Analysis
Unlike bulk viscosity measurements, the NMR technique directly measures diffusion of electrolyte components, allowing insight into how changes in the environment affect each one individually, providing critical information for electrolyte design.
Electrolyte Solvent Analysis A)
In an ideal system, solvent viscosity can be directly related to the three-dimensional diffusion constant by the Stokes-Einstein equation:
In an ideal system, solvent viscosity can be directly related to the three-dimensional diffusion constant by the Stokes-Einstein equation:
where kB is the Boltzmann constant, T is
Unlike bulk viscosity measurements, the NMR technique directly measures diffusion of electrolyte components, allowing insight into how changes in the environment affect each one individually, providing critical information for electrolyte design.
6 5 4 3 2 1 0.0 45 40 35 30 25 20 15 10 5 δ 1H / ppm 0 -5 -10 -15 -20 -25 -30 -35 -40 11 10 9 8 7 B) C) Component Component Ethylene Carbonate Ethylene Carbonate Dimethyl Carbonate Dimethyl Carbonate
Figure 2: Diffusion measurements for an electrolyte solvent mixture of ethylene carbonate (EC) and dimethyl carbonate (DMC). (A) A series of PFGSE spectra at different gradient strengths, showing well-resolved peaks for the two solvent components. (B) Plot of peak integral vs fraction of full gradient strength for the two solvent components. (C) Stejskal-Tanner linear plot, which allows simple calculation of diffusion constants for each component, from the slopes of the lines. The excellent linearity of the plots shows the high stability of the instrument and the strong linear response of the gradient amplifi er.
Figure 2: Diffusion measurements for an electrolyte solvent mixture of ethylene carbonate (EC) and dimethyl carbonate (DMC). (A) A series of PFGSE spectra at different gradient strengths, showing well-resolved peaks for the two solvent components. (C) Stejskal- Tanner linear plot, which allows simple calculation of diffusion constants for each component, from the slopes of the lines. The excellent linearity of the plots shows the high stability of the instrument and the strong linear response of the gradient amplifier.
Figure 2 shows typical NMR diffusion data obtained using Pulsed Field Gradient Spin Echo (PFGSE) experiments for an electrolyte solvent mixture, consisting of ethylene carbonate (EC) and dimethyl carbonate (DMC), measured at 39.5°C. The calculated diffusion constants in Table 1 demonstrate that NMR can easily resolve differences
in behavior in individual components within a mixed solvent, which can be crucial when trying to understand the interaction between the solvents and ionic species. The “Measuring Diffusion at Different Temperatures Using NMR with Pulsed Field Gradients” application note provides a more detailed description of this NMR diffusion analysis method.
where kB is the Boltzmann constant, T is 3 where kB is the Boltzmann constant, T is
Figure 2 shows typical NMR diffusion data obtained using Pulsed Field Gradient Spin Echo (PFGSE) experiments for an electrolyte solvent mixture, consisting of ethylene carbonate (EC) and dimethyl carbonate (DMC), measured at 39.5°C. The calculated diffusion constants in Table 1 demonstrate that NMR can easily resolve differences in behaviour in individual components within a mixed solvent, which can be crucial when trying to understand the interaction between the solvents and ionic species. The “Measuring Diffusion at Different Temperatures Using NMR with Pulsed Field Gradients” application note provides a more detailed description of this NMR diffusion analysis method.
Table 1. Diffusion constants for EC and DC, calculated from the PFGSE experiment.
Component temperature, rH’ is the radius of the molecular sphere,
and ηη is the viscosity. In real solutions, factors such as temperature and molecular interactions affect individual components in different ways. NMR measures diffusion of individual solvent components, providing more information than bulk viscosity measurements and revealing which specific components of a mixture may be critically affected by changes in composition. Moreover, an X-Pulse spectrometer equipped with the variable temperature feature can measure temperature- dependent performance, allowing evaluation of solvent components under a range of battery operating conditions. This information is key in understanding the mechanisms behind differences in solvent behavior, speeding development of new formulations, therefore saving development time and reducing costs.
Ethylene Carbonate
Measuring Ionic Properties of Electrolytes 6.42 x 10-10
Measuring Ionic Properties of Electrolytes Diffusion constant (D) (m2 /s) Dimethyl Carbonate Table 1: Diffusion constants for EC and DC, calculated from the PFGSE experiment.
In an ideal system, solvent viscosity can be directly related to the three-dimensional diffusion constant by the Stokes-Einstein equation:
Benchtop NMR provides crucial information beyond simple diffusion analysis of the organic components of battery electrolytes. The multinuclear capabilities of the X-Pulse benchtop NMR allow a single instrument to analyze the behaviour of many common ionic species. From the diffusion constants
7.38 x 10-10
of the ionic species, the ionic conductivity (ησ) and transference number (t+/-
Conductivity is crucial for lithium-ion batteries, affecting properties such as energy density and speed of charge/discharge cycles (power density). The transference number denotes the fraction of
) is determined. ) is determined.
Benchtop NMR provides crucial information beyond simple diffusion analysis of the organic components of battery electrolytes. The multinuclear capabilities of the X-Pulse benchtop NMR allow a single instrument to analyze the behaviour of many common ionic species. From the diffusion constants
of the ionic species, the ionic conductivity (ησ) and transference number (t+/-
where t+ and t- are the cationic and anionic transference number, respectively, and D+ and D- are the measured diffusion constants for the cation and anion, respectively.
transference number, respectively, and D+ and D- are are where t+ and t- transference number, respectively, and D+ and D- lithium-ion battery. lithium-ion battery.
the measured diffusion constants for the cation and anion, respectively. A large transference number can reduce concentration polarization of electrolytes during charge–discharge steps, producing higher power density. Optimally, t+
the measured diffusion constants for the cation and anion, respectively. A large transference number can reduce concentration polarization of electrolytes during charge–discharge steps, producing higher power density. Optimally, t+
should be close to 1 for a where t+ and t-
and ηη is the viscosity. In real solutions, factors such as temperature and molecular interactions affect individual components in different ways. NMR measures diffusion of individual solvent components, providing more information than bulk viscosity measurements and revealing which specific components of a mixture may be critically affected by changes in composition. Moreover, an X-Pulse spectrometer equipped with the variable temperature feature can measure temperature- dependent performance, allowing evaluation of solvent components under a range of battery operating conditions. This information is key in understanding the mechanisms behind differences in solvent behavior, speeding development of new formulations, therefore saving development time and reducing costs.
0.2
In real solutions, factors such as temperature and molecular interactions affect individual components in different ways. NMR measures diffusion of individual solvent components, providing more information than bulk viscosity measurements and revealing which specifi c components of a mixture may be critically affected by changes in composition. Moreover, an X-Pulse spectrometer equipped with the variable temperature feature can measure temperature-dependent performance, allowing evaluation of solvent components under a range of battery operating conditions. This information is key in understanding the mechanisms behind differences in solvent behaviour, speeding development of new formulations, therefore saving development time and reducing costs.
DMC 0.4 0.6 0.8 faction of full gradinet strength 1.0
-6.0 -5.0 -4.0 -3.0 -2.0 -1.0 0.0
EC
DMC Linear (EC) Linear (DMC)
Diffusion constant (D) (m2/s) /s) Diffusion constant (D) (m2
Measuring Ionic Properties 7.38 x 10-10
6.42 x 10-10 7.38 x 10-10 Table 1: Diffusion constants for EC and DC, calculated from the PFGSE experiment.
In an ideal system, solvent viscosity can be directly related to the three-dimensional diffusion constant by the Stokes-Einstein equation:
In an ideal system, solvent viscosity can be directly related to the three-dimensional diffusion constant by the Stokes-Einstein equation:
Table 1: Diffusion constants for EC and DC, calculated from the PFGSE experiment. 6.42 x 10-10 0.0
temperature, rH’ is the radius of the molecular sphere, EC
where kB is the Boltzmann constant, T is temperature, rH’ is the radius of the molecular sphere, and is the viscosity.
4.0
{ γ² δ² G² (Δ – δ/3) } / × 10� 2.0
Conductivity i affecting prop speed of char The transfere electrical curr ionic species. determined fr an X-Pulse us (PFGSE) expe
⁹m� ².s¹ 6.0
The ionic con self-diffusion species using
where F is the constant, T is bulk molar sa self-diffusion species, respe
Calculating tr straightforwa
Measuring Ionic Properties of Electrolytes
Benchtop NMR provides crucial information beyond simple diffusion analysis of the organic components of battery electrolytes. The multinuclear capabilities of the X-Pulse benchtop NMR allow a single instrument to analyze the behaviour of many common ionic species. From the diffusion constants
of the ionic species, the ionic conductivity (ησ) and transference number (t+/-
) is determined. temperature, rH’ is the radius of the molecular sphere,
and ηη is the viscosity. In real solutions, factors such as temperature and molecular interactions affect individual components in different ways. NMR measures diffusion of individual solvent components, providing more information than bulk viscosity measurements and revealing which specific components of a mixture may be critically affected by changes in composition. Moreover, an X-Pulse spectrometer equipped with the variable temperature feature can measure temperature- dependent performance, allowing evaluation of solvent components under a range of battery operating conditions. This information is key in understanding the mechanisms behind differences in solvent behavior, speeding development of new formulations, therefore saving development time and reducing costs.
of Electrolytes Benchtop NMR provides crucial information beyond simple diffusion analysis of the organic components of battery electrolytes. The multinuclear capabilities of the X-Pulse benchtop NMR allow a single instrument to analyse the behaviour of many common ionic species. From the diffusion constants of the ionic species, the ionic conductivity (σ) and transference number (t+/-) is determined.
Conductivity is crucial for lithium-ion batteries, affecting properties such as energy density and speed of charge/discharge cycles (power density). The transference number denotes the fraction of electrical current carried in the electrolyte by an ionic species. Conveniently, both parameters can be determined from self-diffusion constants obtained on an X-Pulse using the Pulsed Field Gradient Spin Echo (PFGSE) experiment on a single electrolyte sample.
Conductivity is crucial for lithium-ion batteries, affecting properties such as energy density and speed of charge/discharge cycles (power density). The transference number denotes the fraction of electrical current carried in the electrolyte by an ionic species. Conveniently, both parameters can be determined from self-diffusion constants obtained on an X-Pulse using the Pulsed Field Gradient Spin Echo (PFGSE) experiment on a single electrolyte sample.
The ionic conductivity (σ) can be calculated from the self-diffusion constants of the anionic and cationic species using the Nernst- Einstein relationship:
The ionic conductivity (ση) can be calculated from the self-diffusion constants of the anionic and cationic species using the Nernst-Einstein relationship:
species using the Nernst-Einstein relationship:
where F is the Faraday constant, R is the gas constant, T is the absolute temperature, c is the bulk molar salt concentration, and D+ and D- are the self-diffusion constants of the cationic and anionic species, respectively.
where F is the Faraday constant, R is the gas constant, T is the absolute temperature, c is the bulk molar salt concentration, and D+
Calculating transference numbers is even more straightforward, using the simple equations:
and are the cationic and anionic are the cationic and anionic
where F is the Faraday constant, R is the gas constant, T is the absolute temperature, c is the bulk molar salt concentration, and D+
self-diffusion constants of the cationic and anionic species, respectively.
self-diffusion constants of the cationic and anionic species, respectively.
and D- and D-
Calculating transference numbers is even more straightforward, using the simple equations:
Calculating transference numbers is even more straightforward, using the simple equations:
are the
where t+
and t
Conductivity is crucial for lithium-ion batteries, affecting properties such as energy density and speed of charge/discharge cycles (power density). The transference number denotes the fraction of electrical current carried in the electrolyte by an ionic species. Conveniently, both parameters can be determined from self-diffusion constants obtained on an X-Pulse using the Pulsed Field Gradient Spin Echo (PFGSE) experiment on a single electrolyte sample.
The ionic conductivity (ση) can be calculated from the self-diffusion constants of the anionic and cationic
transference n the measured anion, respec reduce conce during charge power density lithium-ion ba
are the
should be close to 1 for a
Peak Integral (a.u)
ln (I/I0)
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