Ion movement measuring device and ion movement measuring method
To accurately detect the moving state of secondary atomic ions at the time of targeted voltage application and the moving state of secondary atomic ions due to diffusion. An ion movement measuring device includes a test specimen and a detector. The test specimen has a first electrode, a second electrode, and an electrolyte disposed between them. The first electrode and the second electrode each have a layer of an identical element, and have the identical potential in a state where no voltage is applied from outside the test specimen. At least the first electrode contains second atoms being isotopes of first atoms at an abundance ratio higher than a natural abundance ratio of the second atoms, the first atoms being present at a highest natural abundance ratio in the element. The detector detects some of ions of the first atoms and the second atoms, which are discharged from the electrolyte.
1 . An ion movement measuring device comprising:
a test specimen having a first electrode, a second electrode, and an electrolyte disposed between the first electrode and the second electrode,
the first electrode and the second electrode each having a layer of an identical element, and being identical to each other in potential in a state where no voltage is applied from outside the test specimen,
at least the first electrode containing first atoms being present at a highest natural abundance ratio in the identical element and second atoms that are isotopes of the first atoms at an abundance ratio higher than a natural abundance ratio of the second atoms in the identical element; and
a detector that detects ions of the first atoms and the second atoms, the ions being discharged from the electrolyte.
2 . The ion movement measuring device according to claim 1 , further comprising a mover that applies a voltage between the first electrode and the second electrode to allow a side of the first electrode to be higher in potential to cause ions of the first atoms and the second atoms to move from the side of the first electrode to a side of the second electrode in the test specimen.
3 . The ion movement measuring device according to claim 1 , wherein the electrolyte has a solid electrolyte,
the identical element is lithium, the first atoms are atoms of lithium-7, and the second atoms are atoms of lithium-6.
4 . The ion movement measuring device according to claim 1 , wherein the second electrode contains the first atoms and contains the second atoms at an abundance ratio higher than the natural abundance ratio of the second atoms in the identical element.
5 . The ion movement measuring device according to claim 1 , wherein the second electrode contains the first atoms at an abundance ratio higher than an abundance ratio of the first atoms contained in the first electrode, and contains the second atoms at an abundance ratio lower than an abundance ratio of the second atoms contained in the first electrode.
6 . The ion movement measuring device according to claim 1 ,
wherein the detector detects ions of the first atoms and the second atoms at a plurality of points in a direction from the side of the first electrode to the side of the second electrode in the test specimen, and
further comprising:
a creator that creates, based on a result of detections by the detector, an actual measurement profile that plots concentration of the ions of the first atoms or the second atoms at the plurality of points;
a calculator that uses a plurality of patterns of diffusion parameters each including a diffusivity coefficient of the ions in the test specimen to calculate, per each of the diffusion parameters, an arithmetic operation profile which is a result of an arithmetic operation for the concentration; and
a determiner that determines, from among the calculated plurality of arithmetic operation profiles, the arithmetic operation profile that is identified to have a smallest deviation from the actual measurement profile to determine the diffusion parameter corresponding to the determined arithmetic operation profile.
7 . The ion movement measuring device according to claim 6 , wherein the diffusion parameters each include the diffusivity coefficient of the ions that diffuse from the electrolyte to one electrode selected from the first electrode and the second electrode and the diffusivity coefficient of the ions that diffuse from the one electrode to the electrolyte.
8 . The ion movement measuring device according to claim 1 , wherein the electrolyte in the test specimen contains at least one selected from an active material, a conductive auxiliary agent, and a binder.
9 . An ion movement measuring method using a test specimen having a first electrode, a second electrode, and an electrolyte disposed between the first electrode and the second electrode,
the first electrode and the second electrode each having a layer of an identical element, and being identical to each other in potential in a state where no voltage is applied from outside the test specimen,
at least the first electrode containing first atoms present at a highest natural abundance ratio in the identical element and second atoms that are isotopes of the first atoms at an abundance ratio higher than a natural abundance ratio of the second atoms in the identical element,
the ion movement measuring method comprising
a detecting step of detecting ions of the first atoms and the second atoms, the ions being discharged from the electrolyte.
10 . The ion movement measuring method according to claim 9 ,
further comprising a moving step of causing ions of the first atoms and the second atoms to move from a side of the first electrode to a side of the second electrode in the test specimen by applying a voltage from outside the test specimen, between the first electrode and the second electrode to allow the side of the first electrode to be higher in potential,
wherein, in the detecting step, ions of the first atoms and the second atoms, the ions being discharged from the electrolyte, during or after the moving step, are detected.
11 . The ion movement measuring method according to claim 10 , wherein the detecting step is performed in a state where an external voltage is not applied to the test specimen after the moving step.
12 . The ion movement measuring method according to claim 11 ,
further comprising a dividing step of dividing the electrolyte between the moving step and the detecting step,
wherein, in the detecting step, ions of the first atoms and the second atoms are discharged from a divided cross section of the electrolyte and are detected.
13 . The ion movement measuring method according to claim 12 , wherein, in the dividing step, the electrolyte is divided such that the divided cross section extends from the first electrode to the second electrode.
14 . The ion movement measuring method according to claim 11 , wherein, in the detecting step, ions discharged from an end face of the electrolyte are detected in a state where the electrolyte is not divided, and
the detecting step is performed at a plurality of time points, each time point corresponding to a different total voltage application time during the moving step.
15 . The ion movement measuring method according to claim 9 , wherein the electrolyte has a solid electrolyte,
the identical element is lithium, the first atoms are atoms of lithium-7, and the second atoms are atoms of lithium-6.
16 . The ion movement measuring method according to claim 9 ,
wherein, in the detecting step, ions of the first atoms and the second atoms are detected at a plurality of points in a direction from the side of the first electrode to the side of the second electrode in the test specimen, and
further comprising:
creating, based on a result of detections in the detecting step, an actual measurement profile that plots concentration of the ions of the first atoms or the second atoms at the plurality of points;
calculating, per each of diffusion parameters, an arithmetic operation profile which is a result of an arithmetic operation for the concentration by using a plurality of patterns of the diffusion parameters each including a diffusivity coefficient of the ions in the test specimen; and
determining, from among the calculated plurality of arithmetic operation profiles, the arithmetic operation profile that is identified to have a smallest deviation from the actual measurement profile to determine the diffusion parameter corresponding to the determined arithmetic operation profile.
17 . The ion movement measuring method according to claim 16 , wherein the diffusion parameters each include the diffusivity coefficient of the ions that diffuse from the electrolyte to one electrode of the first electrode and the second electrode and the diffusivity coefficient of the ions that diffuse from the one electrode to the electrolyte.
18 . The ion movement measuring method according to claim 9 , wherein the electrolyte in the test specimen contains at least one of an active material, a conductive auxiliary agent, or a binder.