Device for detection of ionic conductivity and its applied measurement

Patent metadata

Field	Value
Publication number	US-10054561-B2
Application number	US-201515322138-A
Country	US
Kind code	B2
Filing date	Dec 14, 2015
Priority date	Dec 19, 2014
Publication date	Aug 21, 2018
Grant date	Aug 21, 2018

Abstract

An ionic conductance measuring instrument comprising a voltage/current test device and a test electrode, in which the test electrode comprises a bulk substrate with four linearly arranged through holes, four Pt wires inserted in the through holes respectively with their upper ends exposed outside of the bulk and their downside ends hidden inside of the bulk; the four axis of the Pt wire is in the same plane and parallel with each other; the gap distance between the mentioned Pt wire and the bulk substrate is 0.1-2 mm, and is filled with ionic conductive polymer.

First claim

We claim:

1. An ionic conductance measuring device comprises a voltage/current detection part and a test electrode; the test electrode comprises a block of substrate, four linearly arranged through holes on the substrate, four platinum wires inserted in the holes with the upper tips extended outside the block and the opposite tips withdrawn inside the block, the axes of the through holes, as well as the platinum wires, are parallelly aligned in the same plane, the distance between the lower end surface of the platinum wires and the bottom surface of the block substrate is 0.1-2 mm, and the gaps between the bottom ends of the platinum wires and the substrate are filled with the ion conductive polymer.

2. The ionic conductance measuring device of claim 1 , wherein the voltage/current testing device is one of a potentiostat, ohmmeter, ammeter, constant voltage power supply, and a constant current meter.

3. The ionic conductance measuring device of claim 1 , wherein the distance between the adjacent platinum wires is equal, and the diameters of the platinum wires are equal.

4. The ionic conductance measuring device of claim 1 , wherein the substrate material is one of polytetrafluoroethylene, polyether ether ketone and polyethylene.

5. The ionic conductance measuring device of claim 1 , wherein the ion conductive polymer is one of perfluorosulfonic acid polymer, sulfonated polyetheretherketone, quaternized polysulfone, and polybenzimidazole.

6. The ionic conductance measuring device of claim 1 , wherein the range of the measurement for ionic conductivity is 0.01 to 1000 Ω·cm; the range with minimized error is 0.05 to 100 Ω·cm.

7. The ionic conductance measuring device of claim 1 , wherein the testing device also comprises a temperature/humidity controllable test box, which includes three airtight chambers: a dry gas chamber, a wet gas chamber and a testing chamber;
the probes of the voltage/current testing device and the testing electrode are arranged in the testing chamber;
a gas inlet-A and a dry gas outlet are fixed on the dry gas chamber, and the inside of the dry gas chamber is filled with dehydration material; a gas inlet-B and a moist gas outlet are fixed on the wet gas chamber, and the deionized water is contained in chamber; the gas outlets of the dry and wet gas are connected to the testing chamber by tubes, and the inlets are connected to an gas supply source by gas flow meters.

8. The ionic conductance measuring device of claim 7 , wherein the dry gas outlet and the wet gas outlet are connected with the test chamber pipeline through the three-way valve, and the three ports of the three-way valve are respectively connected with the testing chamber, the dry gas outlet and the wet gas outlet; the gas flow meters are one of the rotor flow rate meters, electromagnetic flow meters, and differential pressure flow meters.

9. The ionic conductance measuring device of claim 7 , wherein the bottom of the test chamber is set with a water outlet, and the water outlet is set with a valve, and the water outlet can be opened or closed, and the water outlet can be opened to discharge liquid water in the test chamber.

10. The ionic conductance measuring device of claim 7 , wherein the test chamber is provided with a sample test table, and the sample test table is drilled with several through holes, which can drain the liquid water to the bottom of the testing chamber.

11. The ionic conductance measuring device of claim 7 , wherein the humidity controllable testing box is provided with a heat keeping device outside, and the dry gas chamber, wet gas chamber and testing chamber are all covered by the heat keeping device.

12. The ionic conductance measuring device of claim 11 , wherein the temperature controlling and keeping device is one of a thermostatic water bath and a electric heating jacket.

13. The ionic conductance measuring device of claim 7 , wherein the dry gas chamber, the wet gas chamber and the testing chamber are made of moisture resistant and heat resistant materials, and the moisture resistant and heat resistant material is one of organic glasses, polytetrafluoroethylene and stainless steel.

14. A method for measuring ionic conductivity using the ionic conductance measuring device of claim 1 comprising the followed steps:
(1) measuring the ionic conductance: a sliced thin piece of the testing sample is tightly pressed on bottom end of the testing electrode block; the second and third platinum wires counted from the left in the test electrode are connected with the potential control terminal, and the first and forth platinum wires counted from the left in the test electrode are connected with the current control terminal; a certain voltage is applied on the voltage testing terminal, and the response current is recorded; the same procedure is repeated at least twice;
(2) data processing: the measured current is set as the abscissa, and the voltage is set as the ordinate; a plot of current-voltage is obtained, and the linear section near the zero potential part is fitted, and the slope d of the fitted curve is the ionic resistance of the sample to be measured;
the ionic resistivity ρ of the test sample is calculated by ρ=Cd, where C is the correction factor and is calculated as follow:
C= 2π/[1/ S 1 +1/ S 2 −1/( S 1 +S 2 )−1/( S 2 +S 3 )]

wherein S 1 , S 2 and S 3 are the distance between the first platinum wire and the second platinum wire counted from the left in the test electrode, the second Pt wire and the third Pt wire, the third Pt wire and the fourth Pt wire, respectively; and
the conductivity of the sample to be measured is 1/ρ.

15. The method of claim 14 , wherein the applied voltage range in step (1) is −1V to 1V.

16. The method of claim 14 , wherein when the length of the test sample on the scale along the line of the connected points of the axes of the platinum wires is more than 10 times of the distance between the Platinum wires, it could be considered to meet the semi-infinite boundary condition, and the conductivity value is calculated directly from the above equation.

17. The method of claim 14 , wherein when the ratio of the sample thickness and the distance between the Platinum wires is less than 0.5, a correction curve is required by testing a series of samples to evaluate the relationships between the sample thickness and the testing positions.

18. The method of claim 14 , wherein the ionic conductivity test method is used to measure the ionic conductivity of samples as carbon paper, carbon powder, carbon fiber, semiconductor, metal, or polymers.

19. The method of claim 14 , wherein the flow rate ratio of the gas inlet A and the gas inlet B is simultaneously introduced, the flow ratio Q A :Q B is equal to X:(1−X), where X is the preset humidity, 0≤X≤100%; the gas is one of nitrogen, argon, air, and oxygen.

Assignees

• Dalian Inst Chem & Physics Cas

Inventors

• Sun Gongquan
• Xia Zhangxun
• Wang Suli
• Fu Xudong

Classifications

• G01N27/06

  of a liquid (involving electrolysis G01N27/26) · CPC title

• G01N27/416

  Systems (G01N27/27 takes precedence) · CPC title

• G01N27/04 Primary

  by investigating resistance · CPC title

• G01R31/36

  Arrangements for testing, measuring or monitoring the electrical condition of accumulators or electric batteries, e.g. capacity or state of charge [SoC] · CPC title

• G01N27/4162

  investigating the composition of gases, by the influence exerted on ionic conductivity in a liquid (conductometry in general G01N27/06; amperometric gas sensors G01N27/404) · CPC title