Battery cell and battery including electroactive material

Abstract

A battery cell which includes at least one negative electrode, at least one positive electrode, and at least one electrolyte, the battery cell further including at least one electroactive material which may be prompted to undergo a change in volume and/or shape by way of an application of a voltage. A battery is also described which includes at least one battery cell, the battery further including at least one electroactive material which may be prompted to undergo a change in volume and/or shape by way of an application of a voltage. A method is also described for compensating for changes in volume and/or shape in a battery cell and in a battery.

Claims

1. A battery including at least one battery cell, wherein the battery further includes at least one electroactive material which may be prompted to undergo a change in at least one of a volume and a shape by way of an application of a voltage, wherein: the battery includes at least two battery cells, the electroactive material being situated between the battery cells, a first one of the battery cells comprises a first housing, a second one of the battery cells comprises a second housing, and the electroactive material is located between the first housing and the second housing.

2. The battery as recited in claim 1, wherein the electroactive material is an electroactive polymer.

Description

BRIEF DESCRIPTION OF THE DRAWINGS

(1) Specific embodiments of the present invention are described in greater detail with reference to the drawings and the following description.

(2) FIG. 1 shows a schematic representation of a conventional battery cell.

(3) FIG. 2 shows a schematic representation of a battery cell according to the present invention.

(4) FIG. 3 shows a schematic representation of alternative specific embodiments of a battery cell according to the present invention.

(5) FIG. 4 shows a schematic representation of a battery according to the present invention.

DETAILED DESCRIPTION OF EXAMPLE EMBODIMENTS

(6) A battery cell 2 is schematically represented in FIG. 1. Battery cell 2 includes a cell housing 3 which is designed to be prismatic, i.e., rectangular in the present case. Cell housing 3 is designed to be electrically conductive in the present case and is made of aluminum, for example. Cell housing 3 may also be made of an electrically insulating material, for example plastic.

(7) Battery cell 2 includes a negative terminal 11 and a positive terminal 12. A voltage provided by battery cell 2 may be tapped via terminals 11, 12. Furthermore, battery cell 2 may also be charged via terminals 11, 12. Terminals 11, 12 are situated spaced apart from each other on a cover surface of, for example, prismatic cell housing 3.

(8) Situated within cell housing 3 of battery cell 2 is an electrode coil or stack which includes two electrodes, namely a negative electrode 21 and a positive electrode 22. Negative electrode 21 and positive electrode 22 are each designed to be foil-like and are wound to form the electrode coil having a separator 18 therebetween. Instead of separator 18, a layer of a solid electrolyte may also be used. It is also conceivable that multiple electrode coils are provided in cell housing 3. Instead of the electrode coil, an electrode stack may also be provided, for example.

(9) Negative electrode 21 includes a negative active material composition 41 which is designed to be foil-like. Negative active material composition 41 includes metallic lithium, for example, as the base material, i.e., the active material. Alternatively, silicon or a silicon-containing alloy or graphite could also be used. Negative electrode 21 further includes a current collector 31 which is designed to be foil-like in the present case. Such an embodiment is not necessary in the case, for example, of an Li-metal anode, since the electrical contact to current collector 31 of negative electrode 21 across farther distances is generally ensured due to the metallic lithium. In the present case, negative active material composition 41 and current collector 31 of negative electrode 21 are placed against each other in a planar manner and are connected to each other. Current collector 31 of negative electrode 21 is designed to be electrically conductive and is made of a metal, for example copper. Current collector 31 of negative electrode 21 is electrically connected to negative terminal 11 of battery cell 2.

(10) Positive electrode 22 is an NCM (nickel-cobalt-manganese) electrode, for example, in the present case. Positive electrode 22 includes a positive active material composition 42 which includes a particulate positive active material. Additives, in particular conductive carbon black and binders, are situated between the particles of the positive active material. The positive active material and the aforementioned additives form positive active material composition 42 in this case, i.e., a composite which is designed to be foil-like.

(11) Positive electrode 22 further includes a current collector 32 which is likewise designed to be foil-like. Positive active material composition 42 and current collector 32 of positive electrode 22 are placed against each other in a planar manner and are connected to each other. Current collector 32 of positive electrode 22 is designed to be electrically conductive and is made of a metal, for example aluminum. Current collector 32 of positive electrode 22 is electrically connected to positive terminal 12 of battery cell 2.

(12) Negative electrode 21 and positive electrode 22 are separated from each other by separator 18. Separator 18 is likewise designed to be foil-like. Separator 18 is designed to be electronically insulating but ionically conductive, i.e., permeable to lithium ions. When a solid electrolyte is used, this separator 18 may possibly not be necessary.

(13) Cell housing 3 of battery cell 2 is filled with a liquid aprotic electrolyte 15 or with a polymer electrolyte. In this case, electrolyte 15 surrounds negative electrode 21, positive electrode 22, and separator 18.

(14) Electrolyte 15 is also ionically conductive and includes, for example, a mixture of at least one cyclic carbonate (for example, ethylene carbonate (EC), propylene carbonate (PC), butylene carbonate (BC)), and at least one linear carbonate (for example, dimethyl carbonate (DMC), diethyl carbonate (DEC), methyl ethyl carbonate (MEC)) as solvents, and a lithium salt (for example, LiPF.sub.6, LiBF.sub.4) as an additive.

(15) A battery cell 2 according to the present invention is schematically represented in FIG. 2. Battery cell 2 likewise includes a cell housing 3 which is designed to be prismatic, i.e., rectangular in the present case. Battery cell 2 is largely similar to battery cell 2 from FIG. 1. Therefore, differences from battery cell 2 from FIG. 1, in particular, will be described in the following.

(16) Separator 18 is made of an electroactive material 50 in the present case. Separator 18 is also designed in such a way, in the present case, that there is a sufficient permeability with respect to the charge carriers from electrolyte 15. In particular, separator 18 is made of a porous electroactive material 50. For example, a foil made of polyvinylidene fluoride (PVDF) or a copolymer, including vinylidene fluoride monomer units, is used. Electroactive material 50 is prompted to undergo a change in volume and/or shape by way of the application of a voltage and, in this way, compensates for the change in volume and/or shape of active material compositions 41, 42 of negative and positive electrodes 21, 22, respectively, and of separator 18 and/or electrolyte 15, which occurs during the charging and discharging process. The voltage may originate from an external voltage source or, as in the present case, may be drawn from battery cell 2 itself.

(17) Additionally or in an alternative specific embodiment, negative active material composition 41 and/or positive active material composition 42 may include an electroactive material 50. For example, a coating made of electroactive material 50 may be applied onto the particles of the negative active material and/or the positive active material. The particles of the particular active material are surrounded by the coating made of electroactive material 50. The coating made of electroactive material 50 therefore surrounds the particles of the active material in negative active material composition 41 and/or in positive active material composition 42. In order to enable a passage of the charge carriers from electrolyte 15 to the active material, the coating made of electroactive material 50 is designed in this case to be permeable, in particular porous.

(18) FIG. 3 shows yet another alternative specific embodiment of a battery cell 2 according to the present invention. In this case, electroactive material 50 is designed to be planar, specifically foil-like in the present case, and is applied on the surface of negative and positive electrodes 21, 22, respectively, of separator 18, or of the inner side of cell housing 3. The connection of electroactive material 50 to the particular voltage source is not shown in FIG. 3 for the sake of clarity of the schematic representation. The individual specific embodiments may be used individually or in combination with each other and, in this way, may be matched to each other in such a way that an optimal result is achieved.

(19) FIG. 4 shows a battery 1, including a pluralityfive in the present caseof individual battery cells 2 which are connected to each other. Layers of electroactive material 50 are situated between battery cells 2. In this case, electroactive material 50 is designed to be planar, specifically foil-like in the present case, and is applied onto the outer surfaces of cell housing 3. The connection of electroactive material 50 to the voltage source is not shown in FIG. 4 for the sake of clarity of the schematic representation. Electroactive material 50 may be applied on each battery cell 2 of battery 1, as necessary, or only on every second, third, fourth, etc., battery cell 2 of battery 1. Battery 1 also includes a battery housing 6 and a negative pole 71 and a positive pole 72 which are connected to negative terminals 11 and positive terminals 12, respectively, of individual battery cells 2.

(20) The present invention is not limited to the exemplary embodiments described here and to the aspects emphasized therein. A multitude of modifications which are within the capabilities of those skilled in the art may rather be possible within the scope of the present invention.