Method and device for determining the amount of a gas present in a battery cell

Patent metadata

Field	Value
Publication number	US-2022011185-A1
Application number	US-202117374336-A
Country	US
Kind code	A1
Filing date	Jul 13, 2021
Priority date	Jul 13, 2020
Publication date	Jan 13, 2022
Grant date	—

Abstract

A method for determining the amount of a gas present in a battery cell, whereby the battery cell has an initial volume, comprises at least the following steps: a) immersing the battery cell into a non-conductive liquid having a defined density at a first ambient pressure; b) generating a lifting force that acts in the opposite direction of a downforce of the battery cell; c) changing the first ambient pressure to a second ambient pressure, and measuring the buoyancy force—which is dependent on the ambient pressure—of the battery cell in the liquid; and d) measuring the amount of gas present in the battery cell, taking into account the first and second ambient pressures, the buoyancy forces ascertained for these ambient pressures, the temperature of the non-conductive liquid and the density of the liquid.

First claim

1 . A method for determining the amount of a gas present in a battery cell, whereby the battery cell has an initial volume, and the method comprises at least the following steps:
a) immersing the battery cell into a non-conductive liquid having a defined density at a first ambient pressure; b) generating a lifting force that acts in the opposite direction of a downforce of the battery cell; c) changing the first ambient pressure to a second ambient pressure, and measuring the buoyancy force—which is dependent on ambient pressure—of the battery cell in the liquid; and d) measuring an amount of gas present in the battery cell, taking into account the first and second ambient pressures, the buoyancy forces ascertained for these ambient pressures, the temperature of the non-conductive liquid and the density of the liquid.

2 . The method according to claim 1 , whereby the non-conductive liquid and the battery cell are kept at a defined temperature during steps a) to d).

3 . The method according to claim 1 , whereby the pressure selected as the second ambient pressure is higher than an internal gas pressure in the battery cell.

4 . The method according to claim 1 , whereby the pressure selected as the second ambient pressure is lower than an internal gas pressure in the battery cell.

5 . The method according to claim 1 , whereby the lifting force is selected in such a way that, together with the buoyancy force, it is equal to or greater than the downforce of the battery cell.

6 . The method according to claim 1 , whereby, in step d), the temperature-dependent solubility of the gas in a liquid present in the battery cell is additionally taken into account.

7 . The method according to claim 1 , whereby the measurement of the parameters during steps a), b) and c) is carried out in a sealed pressure chamber.

8 . The method according to claim 1 , whereby at least a course-over-time curve of the ambient pressure, a temperature curve of the non-conductive liquid or a curve of the buoyancy force are all continuously recorded in order to determine the amount of substance.

9 . The method according to claim 1 , whereby the battery cell has an aged cell whose gas pockets are bulging out and in which an internal gas pressure is greater than the hydrostatic air pressure and is greater than 1 bar.

10 . A device for determining the amount of a gas present in a battery cell, comprising:
a pressure chamber, a liquid container arranged in the pressure chamber, a pressure-measuring means for measuring an ambient pressure, a force-generating means for generating a lifting force, a force-measuring means for measuring a resulting buoyancy force, and a control unit for detecting and processing the acquired measured values and for determining the amount of gas.

11 . The device according to claim 10 , further comprising:
a heater that serves to heat up the non-conductive liquid present in the liquid container, and a temperature-measuring means to measure the temperature of the non-conductive liquid.

12 . A computer program comprising commands configured to cause a computer to carry out the method according to claim 1 .

13 . A computer-readable medium on which the computer program according to claim 11 is stored.

Assignees

• Volkswagen Ag

Inventors

• Rumberg Björn
• Epding Bernd

Classifications

• Y02E60/10

  Energy storage using batteries · CPC title

• G01R31/396 Primary

  Acquisition or processing of data for testing or for monitoring individual cells or groups of cells within a battery · 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

• G01F22/02

  involving measurement of pressure · CPC title

• H01M10/48 Primary

  Accumulators combined with arrangements for measuring, testing or indicating the condition of cells, e.g. the level or density of the electrolyte (constructional details of current conducting connections for detecting conditions inside cells or batteries, e.g. details of voltage sensing terminals, H01M50/569) · CPC title