Rechargeable battery and methods for matching self-discharge rates of battery cells

Abstract

The invention relates to a rechargeable battery (100) comprising a plurality of battery cells (110) and load elements (120), wherein each of the battery cells (110) is assigned to one of the load elements (120) and during a discharge process of one of the battery cells (110) the assigned load element is continuously connected in parallel to the battery cell (110) and is active.

Description

Technical area

[0001] The present invention relates to the field of rechargeable batteries and concerns a rechargeable battery and a method for adjusting self-discharge rates of battery cells. State of the art

[0002] Rechargeable batteries (accumulators) in the form of battery packs are composed of several individual cells or cell blocks (battery cells) that are connected in series to increase the nominal voltage. Due to manufacturing and aging, fluctuations in the capacity and internal resistance of these cells occur. This results in varying self-discharge rates among the cells. This, in turn, leads to varying charge states of the cells. This can lead to deep discharge during discharging and overcharging during charging, with the end-of-charge voltage of individual battery cells being exceeded, even though the overall voltage is still within the nominal operating range. Depending on the battery type, this can lead to irreversible damage to individual cells due to electrolyte decomposition and thus to a loss of capacity of the entire battery pack, and in the worst case, to fires and explosions.Accordingly, if the operating limits of individual battery cells are exceeded or not reached, any protective circuits that may be present will trigger and deactivate the battery pack.

[0003] Differences in the charge level of a battery pack's cells are compensated for by cell balancing. A corresponding electronic circuit is also called a balancer. A technically simple method frequently used in the automotive sector is passive balancing, in which the battery cells are discharged via balancing resistors and the excess energy is converted into heat. However, the corresponding balancing current, which typically ranges from 100 to 300 mA, sometimes leads to significant difficulties in thermal design, for example, with regard to the maximum temperature of components and the temperature profile over the component's lifetime. Disclosure of the invention

[0004] According to the invention, a rechargeable battery and a method for adjusting self-discharge rates of battery cells of a rechargeable battery according to the invention are proposed.

[0005] Further features and details of the invention emerge from the dependent claims, the description, and the drawings. Features and details described in connection with the method according to the invention naturally also apply in connection with the rechargeable battery according to the invention, and vice versa, so that with regard to the disclosure of the individual aspects of the invention, reference is always made to each other.

[0006] According to a first aspect of the invention, a rechargeable battery comprising a plurality of battery cells and load elements is proposed. Each of the battery cells is assigned one of the load elements, with each battery cell preferably being assigned exactly one load element. During a discharging process of one of the battery cells, the assigned load element is continuously connected in parallel with the battery cell and active; thus, the load element is not temporarily deactivated, nor is it temporarily activated and then deactivated again. Such a parallel connection allows the self-discharge rates of the corresponding battery cells to be matched to one another. Through the precise configuration and / or selection of the load elements, these currents can be individually adjusted for each battery cell.Preferably, currents in the range from 0 to 1000 µA, in particular 10 to 1000 µA, preferably 10 to 500 µA, more preferably 10 to 300 µA, even more preferably 10 to 200 µA and most preferably 10 to 100 µA are generated via the load elements, which, in contrast to passive balancing, do not cause any disadvantageous heat development.

[0007] Within the scope of this invention, the terms "self-discharge of a battery cell" and, accordingly, "self-discharge rate" are to be understood not only in relation to internal processes within the battery cell, but also include the discharge of the individual battery cell due to intentionally induced external leakage currents, for example, caused by an associated load element. In other words, the self-discharge rate of a battery cell within the meaning of this invention is the sum of the internal self-discharge rate and the discharge rate due to intentionally induced external leakage currents (external self-discharge rate). The self-discharge rate could therefore also be referred to as the total self-discharge rate.

[0008] In the context of this invention, a load element is understood to be an electrical component or an electrical assembly that can convert electrical energy into heat and / or one or more other forms of energy. A load element can in particular comprise a current sink through which a constant current flows and / or a resistor through which a voltage-dependent current flows. Preferably, at least some of the load elements of the rechargeable battery can be controlled separately from one another, in particular regulated and / or switched on, and / or configured separately from one another. Thus, it is conceivable that a current sink used can be controlled such that the current flowing through it can be adjusted. In general, one or more of the load elements can each have a controllable, for example switchable, and / or configurable current sink that is connected in parallel to that of the battery cells to which the load element is assigned.Particularly preferably, a load element assigned to a battery cell of the rechargeable battery has a behavior dependent on a temperature of the battery cell and / or a current state of charge of the battery cell and is preferably configurable by a control unit, for example based on properties of the battery cell.

[0009] A fundamental idea of ​​this invention is to deliberately subject battery cells of a rechargeable battery to a permanent, external leakage current, or to modify such a current, in order to compensate for the different self-discharge rates of the battery cells within the battery pack, in particular to align them with the highest self-discharge rate. This leads to a higher usable energy content of the battery and a higher effective self-discharge of the rechargeable battery. Such an external leakage current is generated by the parallel-connected load elements. Appropriately selected load elements allow the battery cells to discharge more similarly, which in turn reduces the need for balancing, which is essentially proportional to the difference between the maximum and minimum self-discharge rates across all battery cells.The current through the load elements is so low, typically 0 to 1000 µA, in particular 10 to 1000 µA, preferably 10 to 500 µA, more preferably 10 to 300 µA, even more preferably 10 to 200 µA, and most preferably 10 to 100 µA, that ideally a cell voltage monitoring device used to measure the voltages of the battery cells is not impaired. For example, the voltage drops in the battery cells caused by the discharge currents are normally negligible. The required circuit according to the invention, i.e., the load elements used including their corresponding electrical connections, does not necessarily replace a balancer, but can also be used in parallel with one. This can massively reduce the balancing requirement.

[0010] Advantageously, one or more of the load elements each comprise a plurality of switches and resistors and / or current sinks that can be connected to one of the switches (i.e., switchable resistors and / or switchable current sinks). The switches and the switchable resistors and / or current sinks of a load element are each connected to the battery cell to which the load element is assigned in such a way that the switchable resistors and / or current sinks are connected in parallel to the battery cell after each connection. In this case, the switch and resistor and / or current sink are typically connected in series and form a switch-resistor pair and / or a current sink-resistor pair, which in turn is connected in parallel to the corresponding battery cell.This parallel connection results in an increase in the self-discharge rate of the corresponding battery cell when a corresponding switch is closed, since current can now also flow through the connected resistor and / or the connected current sink. A switch and a resistor, i.e. a switch-resistor pair, can also be part of the same electrical component. The same applies to a current sink. Integration into a common component is made possible by the small currents flowing through the resistor and the correspondingly very low heat generation. Furthermore, the presence of several switchable resistors, which can have the same or different resistance values, and / or several switchable current sinks per battery cell is particularly advantageous, as this further increases the flexibility of the circuit.In this case, it is possible to vary which and / or how many of the switchable resistors and / or current sinks are activated, which in turn allows for flexible adjustment of the self-discharge rate. In this case, the self-discharge rates of the battery cells are generated by parallel-connected external, preferably high-ohm resistors with resistance values ​​starting at 50 kΩ, for example, and especially in the range starting at 1 MΩ.

[0011] Advantageously, the configuration of the load elements, for example, the selection of the resistors and / or the current sinks of a load element and / or the switching of the resistors and / or the current sinks of a load element, is application-dependent. In particular, it is advantageous to load the battery cells with a particularly low, preferably the lowest, self-discharge rate with an additional external leakage current. The self-discharge rates of the battery cells, both with and without connected resistors, can be determined during operation, for example, through direct measurements or based on measurements to determine the balancing requirements of the individual battery cells.The load elements, such as the current sinks and / or the switchable resistors, can be implemented inside or outside a chip, which may also include, for example, a balancer and / or units for measuring the battery cell voltage and / or temperature. Such a chip can implement multiple load elements for multiple battery cells.

[0012] The rechargeable battery can, for example, be a drive battery for a vehicle, for example a lithium-ion accumulator, wherein the circuit according to the invention always remains activated, but may be brought into a different state during various activities of a vehicle, for example when parking, when charging the battery, and / or when driving, i.e. a different configuration for the load elements, for example other switchable resistors and / or other switchable current sinks and / or other switching states for switches in the load elements, may be selected. In general, the rechargeable battery can comprise a battery management system, wherein the load elements of the described circuit according to the invention can be part of the battery management system. The circuit can also exist in parallel with a balancer, which can be part of such a battery management system.The circuit according to the invention can also be implemented in the same chip that is also used, for example, for determining, for example measuring, voltages and / or self-discharge rates of the battery cells.

[0013] The switches preferably comprise or consist of semiconductor switches, for example comprising MOSFETs (metal oxide semiconductor field-effect transistors) and / or antifuses. Due to the relatively low currents in the range of typically 0 to 1000 µA, in particular 10 to 1000 µA, preferably 10 to 500 µA, more preferably 10 to 300 µA, even more preferably 10 to 200 µA, and most preferably 10 to 100 µA, which potentially flow via the load elements and thus also the switches, no stringent requirements are placed on the MOSFETs to be used, and cost-effective implementation is accordingly possible. In contrast to solutions with semiconductor switches, for example implemented using MOSFETs, the use of antifuses allows only a one-time adjustment, for example during production, to optimize the self-discharge rates, but also does not require permanent control.

[0014] The rechargeable battery preferably has a measuring unit for determining the self-discharge rates of the battery cells. It is conceivable that the measuring unit for determining the self-discharge rates performs measurements and / or calculations for processing the measured values, for example, based on measured values ​​measured by other components such as voltage and / or current meters and / or based on knowledge of the status of the load elements assigned to the battery cells. For example, the self-discharge rates of the battery cells can also be determined if only the internal self-discharge rates of the battery cells are measured, but the relevant status of the load elements assigned to the battery cells, in particular their connection, is known, since this information can be used to determine the external self-discharge rate and thus the overall self-discharge rates of the battery cells.

[0015] The rechargeable battery preferably has a control unit for controlling, in particular regulating, one or more of the self-discharge rates of the battery cells, wherein the control of the one or more self-discharge rates is effected by controlling the load elements. For this purpose, control commands in the form of corresponding electrical signals can be sent from the control unit to the load element to be controlled, for example in an integrated chip implementing the load element. In the event that, as described above, one or more of the load elements each have a plurality of switches and resistors and / or current sinks that can be connected to one of the switches, the control can be effected by the control unit switching (closing and / or opening) at least some of the switches and / or changing (increasing and / or decreasing) at least some of the resistors and / or current sinks.This can be achieved, for example, by transmitting corresponding control commands in the form of corresponding electrical signals from the control unit to the switches to be switched and / or the resistors and / or current sinks to be changed. In general, control commands can be transmitted in the form of corresponding electrical signals from the control unit to the load elements and / or current sinks to be controlled and / or configured, for example, to the switches to be switched and / or the resistors to be changed.

[0016] In a rechargeable battery as described above, which has both a measuring unit and a control unit, the control, in particular the regulation, is advantageously carried out by the control unit on the basis of the self-discharge rates determined by the measuring unit. For this purpose, it is conceivable that the measuring unit and control unit are directly connected to one another by means of an electrical connection and that the data required for the control, for example the determined self-discharge rates of the battery cells and / or information determined therefrom, for example regarding the battery cell with the highest and / or the battery cell with the lowest self-discharge rate, are transmitted to the control unit. In the event that the control unit and measuring unit are both parts of the battery, both units can also be identical to one another or one of these units can comprise the other.

[0017] In such a rechargeable battery, the battery cell with the highest and / or the battery cell with the lowest self-discharge rate can preferably be determined by the measuring unit, and the load elements can be controlled by the control unit in such a way, for example switches can be switched and / or current sinks can be controlled and / or resistors can be changed in such a way that one or more, preferably all, of the other self-discharge rates of the battery cells can be adjusted to the highest self-discharge rate. For example, by connecting a resistor to the battery cell with the lowest self-discharge rate, the self-discharge rate can be specifically increased for this cell in order to equalize the self-discharge rates of all batteries. Alternatively, the battery cell with the highest self-discharge rate can also be considered and the self-discharge rates of all other battery cells can be adjusted to this.In both cases, the difference between the highest and lowest discharge rates between the cells is reduced.

[0018] According to a second aspect of the invention, a method for adjusting self-discharge rates of battery cells of a rechargeable battery as described above is proposed, wherein the method comprises determining the self-discharge rates of the battery cells of the rechargeable battery and determining the battery cell with the highest and / or the battery cell with the lowest self-discharge rate. Furthermore, one or more of the self-discharge rates of the battery cells are controlled by controlling the load elements such that one or more of the other self-discharge rates of the battery cells are adjusted to the highest self-discharge rate. For this purpose, the currents flowing through the load elements are adjusted.In the case where, as described above, one or more of the load elements each have a plurality of switches and resistors and / or current sinks that can be connected to one of the switches, the corresponding load elements can be controlled by switching the switches, in particular by connecting the resistors and / or current sinks, and / or by changing, in particular reducing, the resistors and / or by controlling and / or configuring the current sinks. Preferably, only currents of up to 1000 µA, preferably up to 500 µA, more preferably up to 300 µA, even more preferably up to 200 µA, and most preferably up to 100 µA flow through the load elements. These currents are preferably greater than or equal to 10 µA, thus they are preferably in the range from 10 to 1000 µA, preferably 10 to 500 µA, more preferably 10 to 300 µA, even more preferably 10 to 200 µA and most preferably 10 to 100 µA.

[0019] Preferably, the rechargeable battery has a measuring unit for determining the self-discharge rates of the battery cells, and the self-discharge rates of the battery cells are determined by the measuring unit. It is also conceivable for the rechargeable battery to have a control unit for controlling one or more of the self-discharge rates of the battery cells. The control of the one or more self-discharge rates is achieved by the control unit switching, i.e., closing and / or opening, at least some of the switches and / or changing at least some of the resistors and / or controlling and / or configuring at least some of the current sinks, and the control is performed by the control unit.

[0020] The method can include determining the battery cell with the lowest self-discharge rate, and controlling the self-discharge rate by increasing the current flowing through the corresponding load elements. If, as described above, one or more of the load elements each have a plurality of switches and resistors and / or current sinks that can be connected to one of the switches, the corresponding load elements can be controlled by connecting and / or reducing the resistors and / or controlling and / or configuring the current sinks. For example, the battery cell with the lowest self-discharge rate is subjected to an additional load using a high-ohm resistor.

[0021] Likewise, the method can comprise determining the battery cell with the highest self-discharge rate, and controlling the self-discharge rate by optimally adjusting all of the other self-discharge rates to the highest self-discharge rate by increasing the currents flowing through the load elements, i.e., reducing them so that the resulting new self-discharge rates each exhibit the smallest possible difference from the highest self-discharge rate. If one or more of the load elements each have a plurality of switches and resistors and / or current sinks that can be connected to one of the switches, the switches can be connected and / or the resistors can be reduced and / or the current sinks can be controlled and / or configured so that the resulting new self-discharge rates each exhibit the smallest possible difference from the highest self-discharge rate. Advantages of the invention

[0022] The present invention makes it possible to artificially equalize the normally existing self-discharge rates of battery cells in a rechargeable battery, which significantly reduces both the balancing requirement and the duration of the balancing process. For this purpose, the self-discharge rates of the battery cells are determined and increased using switchable resistors. The resistors are preferably selected and / or switched in such a way that the best possible equalization of the self-discharge rates is achieved. Ideally, a circuit for implementing balancing can be dispensed with entirely, or at least designed to be much smaller.

[0023] Reducing balancing also significantly reduces the waste heat that would otherwise be generated during balancing due to the significantly higher currents involved. This heat would otherwise have to be dissipated through complex housing designs and / or cooling concepts to prevent damage to the components. This reduction in unwanted heat generation typically enables a simplified design and thus leads to cost savings. Short description of the drawings

[0024] Embodiments of the invention are explained in more detail with reference to the drawings and the following description.

[0025] They show: Fig. 1 shows in schematic form a section of a battery according to the invention; and Fig. 2A, Fig. 2B shows schematically two possible variants for a battery according to the invention. Embodiments of the invention

[0026] In the following description of the embodiments of the invention, identical or similar elements are designated by the same reference numerals, whereby a repeated description of these elements is omitted in individual cases. The figures only schematically illustrate the subject matter of the invention.

[0027] Fig. Figure 1 schematically illustrates a section of a rechargeable battery 100 according to the invention. It shows a battery cell 110 in the form of an equivalent circuit diagram, wherein the equivalent circuit diagram comprises a voltage source 112, an internal resistance 114, and a resistor 116 connected in parallel with these elements. In this equivalent circuit diagram, the resistor 116 represents the internal self-discharge of the battery cell 110. A load element 120 is assigned to the battery cell 110 and is continuously connected in parallel with the battery cell 110 during a discharge process. This load element 120 is formed by one or more switch-resistor pairs 120a, 120b, 120c connected in parallel with each other and with the battery cell 110, and corresponding electrical connections. Fig. In Figure 1, the two switch-resistor pairs 120b, 120c are shown in dashed lines to indicate that they are optional. Furthermore, the presence of additional battery cells 110 with their associated load elements 120 is indicated by the electrical connections 130 shown in dashed lines.

[0028] It is conceivable that the load element 120 shown and / or the load elements assigned to the other battery cells 110 have more than the three switch-resistor pairs 120a, 120b, 120c shown. This is indicated by the ellipses in the symbol of the load element 120. The switch-resistor pairs 120a, 120b, 120c each comprise a resistor 122a, 122b, 122c and a switch 124a, 124b, 124c. The resistors 122a, 122b, 122c can thus each be connected by one of the switches 124a, 124b, 124c in such a way that, after being connected, they are connected in parallel with the battery cell 110. This means that when switched on, an additional current can flow through them, leading to an increased self-discharge rate of the battery cell 110. The switches 124a, 124b, 124c can be semiconductor switches, for example, implemented using MOSFETs.Instead of or in addition to the resistors, current sinks 123a, 123b, 123c, or any combination of resistors 122a, 122b, 122c and current sinks 123a, 123b, 123c would also be conceivable in the circuit shown. For the sake of simplicity, the description of the . Fig. 1 consistently referred to resistances. The same applies to the Fig. 2A and Fig. 2B.

[0029] Continue in Fig. 1 shows a measuring unit 150 and a control unit 160. The measuring unit 150 serves to determine the self-discharge rates of the battery cell 110, for example based on measured values ​​(arrow 145) of the internal self-discharge rates and knowledge of the position of the switches 124a, 124b, 124c described below. The self-discharge rates and / or the information regarding the battery cell 110 with the highest and / or the battery cell 110 with the lowest self-discharge rate are forwarded to the connected control unit 160 (arrow 155), where suitable control commands, for example for closing and / or opening the switches 124a, 124b, 124c and / or changing the resistors 122a, 122b, 122c, are generated, which are transmitted to the corresponding components of the load element (120) (arrow 165).

[0030] The Fig. 2A and Fig. 2B now show in schematic form in their sub-figures (b), starting from a rechargeable battery 200 not according to the invention shown in the sub-figures (a), two possible variants for a battery 100 according to the invention, wherein three battery cells 110a, 110b, 110c are assumed purely by way of example and the self-discharge rates occurring are given in the form of current values.

[0031] More precisely, in the subfigures (a) the Fig. 2A, Fig. 2B shows how the self-discharge rates of the three battery cells 110a, 110b, 110c of an exemplary non-inventive rechargeable battery 200 without switchable resistors and / or current sinks are represented, respectively, indicated as current values ​​I 11 , I 21 , I 31via fictitious resistors 116a, 116b, 116c connected in parallel to the respective voltage sources. The battery cells 110a, 110b, 110c are hereby, as already in Fig. 1, the battery cell 110 is shown in the form of an equivalent circuit diagram, whereby the internal resistances have been omitted for the sake of clarity. As can be seen, the middle battery cell 110b with a current value of I 21 = 100 µA has the highest internal self-discharge rate, while the internal self-discharge rate for the upper battery cell with I 11 = 10 µA is the lowest. Such different self-discharge rates result in a high balancing requirement.

[0032] Based on this non-inventive rechargeable battery 200, the following are now Fig. 2A and Fig. 2B on their respective right-hand side as partial figures (b) rechargeable batteries 100 according to the invention with different circuit variants are shown as improved variants of the battery 200 according to the invention, wherein an approach for the load elements 120 assigned to the battery cells 110a, 110b, 110c is shown in accordance with Fig. 1 was chosen: Thus, the part figure (b) of the Fig. 2A has a switch-resistor pair 120a per battery cell 110a, 110b, 110c. All three of these switch-resistor pairs 120a are identically constructed and have identical components, in particular identical resistors. After determining the self-discharge rates of the battery cells 110a, 110b, 110c with the switches open (which thus corresponds to determining the internal self-discharge rates), for example using a measuring unit, the battery cell with the highest self-discharge rate can be determined, for example also using the measuring unit. This is in the Fig. 2A, the battery cell 110b. The self-discharge rates of the battery cells 110a, 110b, 110c are now controlled, for example by means of a control unit, by switching the switches of the switch-resistor pairs 120a and 120c. By switching on the corresponding resistors, the self-discharge rates of the battery cells 110a, 110c are adjusted to the self-discharge rate of the battery cell 110b. As in Fig. 2A in the partial figure (b), an additional current I 12 = 50 µA, resulting in a new self-discharge rate of 60 µA for the upper battery cell 110a. For the lowest of the three battery cells 110c, closing the corresponding switch results in the additional current I 32= 50 µA, a new self-discharge rate of 80 µA. This optimally matches the self-discharge rates of both battery cells 110a and 110c to that of the middle battery cell 110b. The maximum difference between the self-discharge rates was reduced from 90 µA to 40 µA, thus more than halving the balancing requirement. In this context, it should be noted that due to the low currents used to increase the self-discharge rates, voltage drops of the battery cells across line resistances and series resistances typically play no role in an implementation of the invention and are therefore not taken into account in the above and following considerations. The measurement of the cell voltages can be carried out unhindered. In contrast, balancing typically has to be paused to perform a measurement.

[0033] In sub-figure (b) of the Fig. Figure 2B shows an approach with three switch-resistor pairs 120a, 120b, 120c, which implement a load element 120. By closing the switches of the switch-resistor pairs 120a, 120b, 120c, currents of 50 µA, 40 µA, and 30 µA are enabled due to the correspondingly selected resistances. Again, the situation regarding the self-discharge rates with open switches is as in sub-figure (b) of the Fig. 2A. Again, after measuring and determining the battery cell with the highest self-discharge rate I 21 = 100 µA, the resistors of the switch-resistor pairs 120a, 120b, 120c are switched on in such a way that the other two battery cells adopt new self-discharge rates that best match this self-discharge rate I 21 = 100 µA. This is shown in the example of Fig.2B is achieved by closing the first two switches of the switch-resistor pairs 120a and 120b assigned to the battery cell 110a: When the switches are closed, an additional current of I 12 = 50 µA and I 13 = 40 µA, i.e., a total of 90 µA, which, due to the original self-discharge rate of 10 µA, leads to a new self-discharge rate of 100 µA for battery cell 110a. In battery cell 110c, however, closing the switches of the second and third switch-resistor pairs leads to a new self-discharge rate that best approximates the self-discharge rate of I 21 = 100 µA. Here, the connection of the corresponding resistors with I 33 = 40 µA and I 34= 30 µA, i.e., a total of 70 µA, which, together with the original self-discharge rate of 30 µA, results in a new self-discharge rate of 100 µA. In this ideal case, all three battery cells 110a, 110b, and 110c assume a self-discharge rate of 100 µA with the switch configuration shown in sub-figure (b). Theoretically, balancing is no longer necessary due to the uniform self-discharge.

[0034] The invention is not limited to the embodiments described here and the aspects highlighted therein. Rather, numerous modifications are possible within the scope of the claims, which are within the scope of one skilled in the art.

Claims

[1] Rechargeable battery (100) comprising a plurality of battery cells (110, 110a, 110b, 110c) and load elements (120), wherein each of the battery cells (110, 110a, 110b, 110c) is assigned one of the load elements (120) and during a discharge process of one of the battery cells (110, 110a, 110b, 110c), the assigned load element (120) is continuously connected in parallel to the battery cell (110, 110a, 110b, 110c) and is active. [2] Rechargeable battery (100) according to claim 1, wherein one or more of the load elements (120) each have a controllable and / or configurable current sink (123a, 123b, 123c) connected in parallel with that of the battery cells (110, 110a, 110b, 110c) to which the load element (120) is assigned. [3] Rechargeable battery (100) according to claim 1 or 2, wherein at least some of the load elements (120) are separately configurable and / or controllable. [4] Rechargeable battery (100) according to one of the preceding claims, wherein one or more of the load elements (120) each have a plurality of switches (124a, 124b, 124c) and resistors (122a, 122b, 122c) and / or current sinks (123a, 123b, 123c) that can be connected to one of the switches (124a, 124b, 124c), wherein the switches (124a, 124b, 124c) and the resistors (122a, 122b, 122c) and / or current sinks (123a, 123b, 123c) that can be connected to a load element (120) are each connected to the battery cell (110, 110a, 110b, 110c) in such a way that to which the load element is assigned, so that the switchable resistors (122a, 122b, 122c) and / or current sinks (123a, 123b, 123c) are connected in parallel to the battery cell (110, 110a, 110b, 110c) after each connection. [5] Rechargeable battery (100) according to claim 4, wherein the switches (124a, 124b, 124c) comprise or consist of semiconductor switches and / or antifuses. [6] Rechargeable battery (100) according to one of the preceding claims, wherein the battery (100) has a measuring unit (150) for determining the self-discharge rates of the battery cells (110, 110a, 110b, 110c). [7] Rechargeable battery (100) according to one of the preceding claims, wherein the battery (100) has a control unit (160) for controlling, in particular regulating, one or more of the self-discharge rates of the battery cells (110, 110a, 110b, 110c), wherein the control of the one or more self-discharge rates is carried out by controlling the load elements (120). [8] Rechargeable battery (100) according to claim 6 and claim 7, wherein the control of the control unit (160) is carried out on the basis of the self-discharge rates determined by the measuring unit (150). [9] Rechargeable battery (100) according to claim 8, wherein the battery cell (110b) with the highest and / or the battery cell (110a) with the lowest self-discharge rate can be determined by the measuring unit (150) and the load elements (120) can be controlled by the control unit (160) such that one or more, preferably all other self-discharge rates of the battery cells (110, 110a, 110b, 110c) can be adjusted to the highest self-discharge rate. [10] A method for adjusting self-discharge rates of battery cells (110, 110a, 110b, 110c) of a rechargeable battery (100) according to any one of claims 1 to 9, the method comprising the following steps: a. determining the self-discharge rates of the battery cells (110, 110a, 110b, 110c) of the rechargeable battery (100); b. Determining the battery cell (110b) with the highest and / or the battery cell (110a) with the lowest self-discharge rate; and c. Controlling one or more of the self-discharge rates of the battery cells (110, 110a, 110b, 110c) by controlling the load elements (120) such that one or more of the other self-discharge rates of the battery cells (110, 110a, 110b, 110c) are adjusted to the highest self-discharge rate and preferably only currents of up to 1000 µA, preferably up to 500 µA, more preferably up to 300 µA, even more preferably up to 200 µA and most preferably up to 100 µA flow via the load elements (120). [11] The method of claim 10, wherein • the rechargeable battery (100) is a rechargeable battery according to one of claims 6 to 9 and the determination is carried out by the measuring unit (150); and / or • the rechargeable battery (100) is a rechargeable battery according to one of claims 7 to 9 and the control is carried out by the control unit (160). [12] Method according to claim 10 or 11, wherein the battery cell (110a) with the lowest self-discharge rate is determined and the control is carried out by increasing the self-discharge rate by increasing the current flowing through the corresponding load elements (120). [13] Method according to one of claims 10 to 12, wherein the battery cell (110b) with the highest self-discharge rate is determined and the control is carried out by adjusting all other self-discharge rates to the highest self-discharge rate as best as possible by increasing the currents flowing through the load elements (120).

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