RECHARGEABLE BATTERY PACK HAVING A POUCH CELL, AND METHOD

Abstract

A rechargeable battery pack having at least two pouch cells stacked on top of one another, wherein each of the pouch cells is enclosed in a metal foil, wherein the metal foils are electrically insulated from one another and electrical contact is made with each of the metal foils for the purpose of measuring a capacitor capacitance formed by the metal foils.

Claims

1-11. (canceled)

12: A rechargeable battery pack comprising: at least two pouch cells stacked on top of one another, each of the pouch cells being enclosed in a metal foil; the metal foils being electrically insulated from one another and electrical contact being made with each of the metal foils for the purpose of measuring a capacitor capacitance formed by the metal foils.

13: The rechargeable battery pack as recited in claim 12 further comprising a capacitance measuring circuit electrically connected to the metal foils.

14: The rechargeable battery pack as recited in claim 13 further comprising a battery management system designed to interrupt or reduce a current draw from the rechargeable battery pack when a value of the capacitor capacitance changes by a predefined threshold value.

15: The rechargeable battery pack as recited in claim 14 further comprising a filter circuit configured to filter out a change in the capacitor capacitance induced by impact or vibration.

16: The rechargeable battery pack as recited in claim 13 further comprising a filter circuit configured to filter out a change in the capacitor capacitance induced by impact or vibration.

17: The rechargeable battery pack as recited in claim 12 wherein the metal foils are spaced apart from one another in the stacking direction by an air gap.

18: The rechargeable battery pack as recited in claim 17 further comprising a dielectric introduced in the air gap.

19. The rechargeable battery pack as recited in claim 18 wherein the dielectric is a plastic.

20: The rechargeable battery pack as recited in claim 12 wherein the metal foils are each a metal composite foil.

21: The rechargeable battery pack as recited in claim 20 wherein the metal foils are each an aluminum composite foil.

22: The rechargeable battery pack as recited in claim 20 wherein the dielectric is part of at least one of the metal composite foils.

23: A method for measuring the swelling of a pouch cell of a rechargeable battery pack as recited in claim 12, the method comprising evaluating a change in the capacitor capacitance formed between the metal foils as a measure of the swelling of the pouch cell.

24: The method as recited in claim 23 further comprising interrupting or reducing a current draw from the rechargeable battery pack when the value of the capacitor capacitance changes by a predefined threshold value.

Description

BRIEF DESCRIPTION OF THE DRAWINGS

[0014] Further advantages will become apparent from the following description of the figures. Various exemplary embodiments of the present invention are illustrated in the figures. The figures, the description and the claims contain numerous features in combination. A person skilled in the art will expediently also consider the features individually and combine them to form useful further combinations.

[0015] In the figures, identical and similar components are denoted by the same reference signs.

[0016] FIG. 1A shows a first preferred exemplary embodiment of a rechargeable battery pack according to the invention in a normal state of the pouch cells.

[0017] FIG. 1B shows the first preferred exemplary embodiment of the rechargeable battery pack according to the invention in an expanded or swollen state of the pouch cells.

DETAILED DESCRIPTION

[0018] A preferred exemplary embodiment of a rechargeable battery pack 100 according to the invention is illustrated in FIG. 1.

[0019] The rechargeable battery pack is equipped, for example, with two pouch cells 10, 10′ stacked on top of one another in the stacking direction SR. Each of the pouch cells 10, 10′ is enclosed in a metal foil 11, 11′. The metal foils 11, 11′ are provided as aluminum composite foils and are electrically insulated from one another. The metal foils 11, 11′ are spaced apart from one another in the stacking direction by an air gap 15.

[0020] The mutually facing sides of the metal foils 11, 11′ each define an electrode 12, 12′, wherein an electrical capacitor capacitance exists between the electrodes 12, 12′—which are spaced apart from one another and electrically insulated from one another.

[0021] The value of the electrical capacitor capacitance depends on the distance between the electrodes 12, 12′. This shall be explained in more detail with reference to the subfigures, where FIG. 1A shows the rechargeable battery pack 100 in the normal (desired) state ZN, that is to say the pouch cells 10, 10′ are not expanded.

[0022] FIG. 1B shows the rechargeable battery pack 100 in the swollen (aged) state ZA, wherein the pouch cells 10, 10′ are visibly swollen in the stacking direction SR. In the swollen (aged) state ZA in FIG. 1B, the electrodes 12, 12′ are, for example, spaced further apart from one another (at least on average spaced further apart from one another) than the electrodes 12, 12′ in FIG. 1A. Thus the capacitor capacitance CN existing between the electrodes 12, 12′ of the rechargeable battery pack 100 in FIG. 1A is greater than the capacitor capacitance CA existing between the electrodes 12, 12′ of the rechargeable battery pack 100 in FIG. 1B.

[0023] This change in the capacitor capacitance can be used to detect swelling of the pouch cells 10, 10′. For this, electrical contact is made with each of the metal foils 11, 11′- and thus also the electrodes 12, 12′—via an electrical contact 13, 13′. The electrical contact 13, 13′ is in turn electrically connected to a capacitance measuring circuit 20 which can be used to measure the capacitor capacitance which varies as the cell ages.

[0024] As can be gathered from FIGS. 1A and 1B, an additional dielectric 17 is introduced into the air gap 15 between the pouch cells 10, 10′.

[0025] It should be mentioned that, for the measuring principle proposed here, the air present between the pouch cells 10, 10′ can in itself already be sufficient as a dielectric. Due to the introduced dielectric 17—here, for example, in the form of a plastic strip—the capacitor capacitance is in principle advantageously increased and the pouch cells 10, 10′ are simultaneously supported against one another.

LIST OF REFERENCE SIGNS

[0026] 10, 10′ Pouch cell [0027] 11, 11′ Metal foil [0028] 12, 12′ Electrode [0029] 13, 13′ Electrical contact [0030] 15 Air gap [0031] 17 Dielectric [0032] 20 Capacitance measuring circuit [0033] 100 Rechargeable battery pack [0034] SR Stacking direction [0035] CA Capacitor capacitance for an expanded pouch cell [0036] CN Capacitor capacitance for a normal pouch cell [0037] ZA Swollen state [0038] ZN Normal state