DE102019125990B4 - Battery cell arrangement for a power tool - Google Patents

Abstract

Battery cell arrangement (3) for a power tool (1) with multiple lithium-ion cells (Z1 to Z4), - multiple electrical double-layer capacitors (C11, C12, C21, C22) and - a battery management system (BMS) for controlling the multiple lithium ion cells (Z1 to Z4) and the plurality of electric double layer capacitors (C11, C12, C21, C22), wherein- to one of the plurality of lithium ion cells (Z1 to Z4) or to a pair of the plurality of lithium ions connected in parallel -cells (Z1 to Z4) each have exactly two series-connected electric double-layer capacitors (C11, C12, C21, C22) connected in parallel to form a module (M1, M2),- the battery cell arrangement has a plurality of such modules and - Each module (M1, M2) is individually controlled as a whole by the battery management system (BMS).

Description

The present invention relates to a battery cell arrangement for a power tool with a number of lithium-ion cells, a number of electric double-layer capacitors and a battery management system for controlling the number of lithium-ion cells and the number of electric double-layer capacitors.

The electrical performance of a battery cell arrangement (hereinafter also called accumulator or battery pack) can be improved in that the electrical performance of the cells themselves is not promoted, but rather that electrical high-performance capacitors are operated in parallel with the battery cells. Double-layer capacitors, also referred to as "supercaps" or EDLCs (electric double-layer capacitors), should be particularly suitable. If high-performance capacitors are connected independently of the cells in the battery pack as energy storage via a battery management system, there is always the challenge of carrying out charging and discharging in a controlled manner, not overloading the capacitors, but at the same time not overloading the lithium-ion cells either. The latter can certainly happen in decoupled operation if different voltages are set in the electrochemical or dielectric system as a result of charging or discharging processes. In such cases, high currents occur as soon as the electrochemical cells are connected to the dielectric capacitors in a circuit and physics tries to equalize the potential differences with a very fast charge exchange (high current flows). Against this background, the management of a separate dielectric high-performance capacitor, which is operated decoupled from the electrochemical cells, is always associated with a high outlay on control technology.

Such a battery cell arrangement is, for example, from the publication US 2011/0064977 A1 known. The battery cell arrangement there consists of a series-parallel connection of battery cells and double-layer capacitors. For example, a series of five double-layer capacitors is connected in parallel with a series of ten battery cells. In this way, high currents can be made available in the short term. In particular, capacities corresponding to 20 to 30 times the nominal capacities can be achieved.

In addition, the document describes U.S. 9,819,064 B2 a system for protection against overcharging and charge balancing in combined power source systems. Supercaps or double-layer capacitors are connected in parallel with an energy storage device, which has lithium-ion cells, for example. For example, a series of six double-layer capacitors is connected in parallel with a series of lithium-ion cells. The individual series are controlled via separate switches.

In addition, print describes US 2015/0054428 A1 a method of dissipating inductive energy from cells. A capacitive element with several capacitors is in parallel with a cell and its inductance.

pamphlet US 2016/0087460 A1 discloses supercapacitor structures having multiple supercapacitor cells. The cells can be interconnected individually to provide different currents and voltages for the loads.

The object of the present invention is to make it easier to control the battery cell arrangement with lithium-ion cells and double-layer capacitors.

According to the invention, this object is achieved by a battery cell arrangement according to claim 1. Advantageous developments of the invention result from the dependent claims.

Accordingly, according to the present invention, a battery cell arrangement for a power tool with a number of lithium-ion cells and a number of electric double-layer capacitors is provided. If necessary, the battery cell arrangement has a housing in which at least one positive pole and one negative pole are routed to the outside. The battery cell arrangement is suitable for a power tool that is implemented, for example, as a cordless screwdriver, cordless drill, cordless circular saw, cordless garden tool or the like. The power tool can also be a household appliance and in particular a cleaning appliance.

The battery cell arrangement has several lithium-ion cells. A typical 18V lithium-ion cell battery pack has five, ten, or other multiples of five lithium-ion cells. In addition, the battery cell arrangement has a number of electric double-layer capacitors. Double layer capacitors or supercaps are electrochemical capacitors. Although they only have about ten percent of the energy density of conventional accumulators, their power density is about ten to one hundred times greater. Double-layer capacitors can therefore be charged and discharged much faster become the The capacitance of a double-layer capacitor results from the sum of two storage principles. On the one hand, electrical energy is stored statically by charge separation in Helmholtz double layers in a double layer capacitance. On the other hand, electrical energy is stored electrochemically by Faraday charge exchange with the aid of redox reactions in a pseudocapacitance.

Furthermore, the battery cell arrangement has a battery management system for controlling the multiple lithium-ion cells and the multiple electric double layer capacitors. Such a battery management system usually controls the electrical variables such as current and voltage both when charging and when discharging the cells and capacitors. As a rule, the battery management system controls corresponding semiconductor switches in the battery cell arrangement. Where appropriate, the switches are also part of the battery management system. It is particularly important not to overload the individual cells or capacitors. In particular, the lithium-ion cells must not be chemically or thermally overloaded. A suitable battery management system ensures that such overloads do not occur and the service life of such a battery cell arrangement is correspondingly high.

According to the present invention, exactly two series-connected electric double-layer capacitors are connected in parallel to one of the several lithium-ion cells or to a pair of parallel-connected ones of the several lithium-ion cells, in order to form a module. The lithium ion cells and double layer capacitors of the battery cell assembly are thus grouped into modules. If necessary, more than two lithium-ion cells are also connected in parallel with one another, and precisely two electric double-layer capacitors connected in series are then in turn connected in parallel with this parallel connection. This makes use of the fact that the typical operating voltage of a single lithium-ion cell is 2.5 V to 4.3 V, while the maximum operating voltage of a double-layer capacitor conveniently does not exceed 2.3 V. Two double-layer capacitors in series therefore have approximately the same maximum voltage as a single lithium-ion cell or such lithium-ion cells connected in parallel. This means that each module can be controlled as a whole, and not every lithium cell or parallel connection of lithium cells and every double-layer capacitor has to be controlled individually. Rather, according to the invention, the module or each module of the battery cell arrangement is controlled individually by the battery management system. In this way, the battery management system or the control of the battery cell arrangement can be significantly simplified, because each individual storage component does not have to be controlled individually. Nevertheless, a comparatively individual control of the lithium-ion cells and double-layer capacitors at module level is possible, whereas in the prior art often only a larger series of lithium-ion cells and a likewise larger series of double-layer capacitors can be controlled individually.

In an advantageous embodiment of the battery cell arrangement according to the invention, it has several modules of the type mentioned and each of the several modules is connected separately to the battery management system via a respective switching device. In particular, such a switching device includes one or more semiconductor switches. Such switches or switching devices make it possible to switch the individual modules out of a group or to switch them into a group or to switch off the main current. Accordingly, there is a more or less high output voltage when the modules are connected in series. Otherwise, if modules are also connected in parallel, the current intensity of the battery cell arrangement can be kept correspondingly high during charging or discharging by the switching devices.

In particular, at least one further lithium-ion cell can be connected in parallel with the respective pair of lithium-ion cells in the module or in each of the plurality of modules. In this case, as already indicated above, for example three, four, five or more lithium-ion cells are connected in parallel in a module. Depending on the power requirement, the number of lithium-ion cells connected in parallel in a module can be adjusted.

In addition, it can be provided that in the battery cell arrangement a Zener diode or another electrical or electronic switching element is connected in parallel to each of the double-layer capacitors. Such a switching element should possibly have a limitation functionality similar to that of a zener diode with the battery management system. A zener diode in parallel with a double layer capacitor means that the double layer capacitor cannot be charged above the zener voltage. This protects the double layer capacitor from overvoltages. The same goal can be achieved by a switching element at a predetermined maximum voltage further charging of the double-layer capacitor is prevented.

In addition, a battery cell arrangement for a power tool with a plurality of cylindrical electrochemical cells and at least one cylindrical electrical capacitor can be provided. The power tool can again be of the type mentioned above. The cylindrical electrochemical cells are lithium ion cells. As mentioned, the battery cell arrangement has one or more cylindrical electrical capacitors. These capacitors are supercaps. The cylindrical shape of both the electrochemical cells and the capacitors means that these components can preferably have the shape of a circular cylinder, but can also have the shape of an oval or elliptical cylinder.

Parallel longitudinal axes of (e.g. four of) a plurality of electrochemical cells form the corner points of a polygon, e.g. a rectangle, in an axial plan view. A top view in the direction of the parallel longitudinal axes results in points that can be interpreted as corner points of a polygon. The polygon can be regular or irregular. The polygon can be, for example, a triangle, a square, a pentagon, a hexagon and the like. A longitudinal axis of the at least one capacitor lies parallel to the longitudinal axes of the electrochemical cells and in an axial plan view at the center of the area of the polygon. This means that the capacitor or, for example, a plurality of capacitors connected in series can utilize or partially fill the space between the electrochemical cells arranged in the polygon. As a result, a battery cell arrangement can be made more compact. This is because the free spaces that arise between the electrochemical cells are largely occupied by the one or more capacitors.

The plurality of cylindrical electric capacitors are each double layer capacitors. Such double-layer capacitors are distinguished by their high power density. They enable sufficient power to be provided, especially in the case of power tools in critical situations. This is the case, for example, when a circular saw cuts into dirt (e.g. nails) in the wood, cuts into wood after idling or the processing depth of a milling cutter changes suddenly. In any case, there is an instantaneous increase in the power requirement which, under certain circumstances, cannot be met by the electrochemical cells. Double-layer capacitors, on the other hand, are more able to cope with such jumps in performance.

In addition, it is provided that exactly two series-connected, cylindrical electrical capacitors are connected in parallel to each of the plurality of electrochemical cells, the longitudinal axes of the two series-connected capacitors being identical. Such a configuration is particularly advantageous when a lithium-ion cell is connected in parallel with two electrical double-layer capacitors because, as already mentioned above, the two double-layer capacitors in series typically have a similar or the same maximum operating voltage as the typical maximum operating voltage of a lithium ion cell.

In an advantageous embodiment of the battery cell arrangement, the plurality of cylindrical electrochemical cells are connected in parallel in pairs. Such a pair of cylindrical electrochemical cells arranged in parallel and touching at the shell can be regarded as a module or smallest battery cell unit together with one or two cylindrical capacitors which are arranged on or between the two electrochemical cells and touch them. Such smallest units can then be arranged one behind the other in such a way that, when viewed from above, one electrical capacitor is located in the center of the area of three, four, five etc. electrochemical cells. In this way, the installation space can be utilized to a large extent.

In a particularly preferred configuration of the battery cell arrangement, a plurality of modules, each consisting of two electrochemical cells and two capacitors, are arranged next to one another in antiparallel pairs. This means that one module has all the positive terminals of the electrochemical cells and the capacitor or capacitors pointing in one direction, while the positive terminals of all components of an adjacent module point in the opposite direction. In this case, several modules can be contacted particularly easily in an electrical series connection if they are arranged geometrically in parallel.

In particular, this anti-parallel module structure enables positive electrodes of the electrochemical cells and a positive electrode of one of the capacitors of a first of the plurality of modules to be connected by means of a one-piece, in particular flat, connecting element with negative electrodes of the two electrochemical cells and a negative electrode of one of the capacitors from one to adjacent to the first module second module of the plurality of modules is electrically connected. The individual components of the battery cell arrangement can be connected very inexpensively in this way. In particular, it is possible that with a single metal plate as the connecting element, three (possibly more) positive poles or positive electrodes (two electrochemical cells and a capacitor) of a first module with three (possibly more) negative poles or negative electrodes of a second module are mechanically and electrically connected.

In a special configuration of the battery cell arrangement, the polygon is a rectangle and in particular a square. The cylindrical electrochemical cells thus form the rectangle or square when viewed from above. In this case, the space between the electrochemical cells can largely be filled by the capacitor or capacitors.

As already indicated above, the electrochemical cells are each lithium-ion cells. Such cylindrical lithium-ion cells, for example in the 18650 or 21700 design, are very widely used.

As has already been indicated in the above statements, a power tool can be equipped with a battery cell arrangement. In particular, a respective battery cell arrangement can be used so that a relatively simple battery management system is used. If the compact cell-capacitor arrangement described above is used as an alternative or in addition, the corresponding battery pack or the power tool can be designed very compact overall.

• 1 eine schematische Ansicht eines Elektrowerkzeugs;
• 2 ein Schaltbild einer Batteriezellenanordnung;
• 3 eine Seitenansicht einer Batteriezellenanordnung mit zylinderförmigen elektrochemischen Zellen und zylinderförmigen elektrochemischen Kondensatoren; und
• 4 eine Draufsicht auf die Batteriezellenanordnung von 3.

The present invention will now be explained in more detail with reference to the attached drawings, in which show:

• 1 a schematic view of a power tool;
• 2 a circuit diagram of a battery cell arrangement;
• 3 a side view of a battery cell arrangement with cylindrical electrochemical cells and cylindrical electrochemical capacitors; and
• 4 a plan view of the battery cell assembly of 3 .

The exemplary embodiments described in more detail below represent preferred embodiments of the present invention. In the figures, identical or functionally identical elements have been provided with the same reference symbols.

An electrical device or tool in the form of a cordless drill/driver 1 is shown in a perspective view in 1 shown. A battery pack 2, ie a battery cell arrangement or battery device including the housing, is attached to the cordless drill 1. The battery pack 2 is used to supply energy to the cordless drill 1. It can have, for example, several lithium-ion cells for supplying energy. Other cell technologies are also possible. The following explanations are not only for an electrical device in the form of the cordless drill 1, but generally for any electrical devices such as power tools of any kind, stationary machines, cleaning devices, gardening tools, water pumps and the like.

The invention is based on the approach that (dielectric) capacitors are connected directly in parallel with the electrochemical cells, in particular lithium-ion cells, and can therefore be routed like a single lithium-ion cell on the current and voltage side.

In one example, a configuration of series-connected high-performance capacitors, each to be connected directly in parallel with a respective lithium-ion cell, or in the case of a more powerful battery pack, a configuration of several parallel-connected lithium-ion cells. If double-layer capacitors are used, the configuration of two serially connected double-layer capacitors (EDLCs) with one or more parallel-connected lithium-ion cells is particularly preferred. The reason for this is that the upper voltage limit for double-layer capacitors, at 2.3 to 2.6 V, is lower than the end-of-charge voltage of lithium-ion cells (e.g. 4.2 to 4.5 V). The two double-layer capacitors connected in series share the voltage applied to the lithium-ion cells and are therefore always within a safe window on the voltage side. Such a configuration can be serially expanded to any pack voltages. For a particularly powerful variant of a battery cell arrangement, around five modules, each consisting of two serial double-layer capacitors and one or two parallel lithium-ion cells, could be used.

This type of integration of the high-performance or double-layer capacitors can be managed using the same principles as are already used today in battery management for lithium-ion power batteries. It is possible to use the dielectric in the battery management system of such a battery pack Capacities for power peaks that occur must be taken into account, so that such powerful battery packs can cover significantly higher peak loads.

2 shows a basic circuit diagram of an example of a battery cell arrangement according to the invention. The battery cell arrangement has several lithium-ion cells Z1 and Z2. In addition, the battery cell assembly has multiple electric double layer capacitors C11, C12, C21 and C22. The two double-layer capacitors C11 and C12 are connected in series with one another, and this series connection is connected in parallel with the first lithium-ion cell Z1. In the same way, the double-layer capacitors C21 and C22 are connected in series with one another, and this series connection is connected in parallel with the second lithium-ion cell Z2.

The first lithium-ion cell Z1 and the associated double-layer capacitors C11 and C12 are part of a first module M1. Likewise, the second lithium-ion cell Z2 is part of a second module M2 together with the double-layer capacitors C21 and C22. The two modules M1 and M2 can be connected in series. Furthermore, other modules of this type (in 2 not shown) connected in series to the two modules M1 and M2. This means that in each additional module, as in modules M1 and M2, exactly two double-layer capacitors are connected in series in parallel with a single lithium-ion cell.

Optionally, at least one further lithium-ion cell can be connected in parallel with the respective lithium-ion cell in at least one of the modules or in each of the modules. For example, a third lithium-ion cell Z3 can be connected in parallel with the first lithium-ion cell Z1 in the module M1. At least one further lithium-ion cell can be connected in parallel with these parallel lithium-ion cells Z1 and Z3. In the same way, a fourth lithium-ion cell Z4 can be connected in parallel with the second lithium-ion cell Z2 in the module M2. At least one further lithium-ion cell can be connected in parallel with these parallel lithium-ion cells Z2 and Z4.

The battery cell arrangement can have a main switch SO for switching the main current path on and off with the modules connected in series. The first module M1 optionally has a switching device S1 (e.g. changeover switch). This switching device S1 can be used to bypass the first module M1. For this purpose, the switching device S1 can switch to a bypass which is parallel to the first lithium-ion cell Z1 or parallel to the series connection of the double-layer capacitors C11 and C12. In the same way, the second module M2 can have a second switching device S2 (e.g. changeover switch) with which the second module M2 can be bypassed. For this purpose, the second switching device S2 can switch to a bypass which is parallel to the second lithium-ion cell Z2 or parallel to the series connection of the double-layer capacitors C21 and C22. If the respective switching device S1 or S2 is connected to the respective cells or capacitors (not to the respective bypass), the corresponding module M1, M2 is electrically coupled to the main current path and contributes to the output voltage of the battery cell arrangement.

The switching devices S1 and S2 are in 2 purely symbolically indicated. They can be configured as desired and have the function of controlling the respective module M1 or M2, activated by a battery management system BMS. Each switching device can optionally have a large number of components. In particular, corresponding semiconductor switches can be used for the switching function.

In order to protect the double-layer capacitors C11, C12, C21, C22 or their electrochemical components, the voltage across a double-layer capacitor can be limited with a zener diode. For the sake of clarity, such zener diodes are 2 not marked. As an alternative to the zener diode, any other switching device or any other switching element can also be connected to the respective double-layer capacitor in order to limit its maximum voltage.

A particular advantage is that each module M1, M2 etc. can be controlled individually with the battery management system BMS. It is not necessary to control each individual lithium-ion cell or each individual double-layer capacitor with the BMS battery management system. Due to the fact that the respective lithium-ion cell and the two double-layer capacitors connected in series are matched to one another in terms of voltage, it is sufficient for the respective module with these three components to be controlled individually by the battery management system. Despite this modular control, it can be guaranteed that neither the electrochemistry of the lithium-ion cells nor that of the double-layer capacitors is overtaxed.

3 and 4 show a possible geometric arrangement of individual components of a battery cell arrangement 3. 3 represents a side view while 4 one belonging corresponds to the top view. The battery cell arrangement shown in both figures is very compact and comprises ten individual electrochemical cells 4. Each of these electrochemical cells 4 has a positive pole 5 as a button-like projection and a negative pole (in the 3 and 4 not visible). The electrochemical cells 4 are connected here in pairs in parallel. All pairs (here five pairs) are connected in series in the present example. The geometric arrangement of each pair is selected such that adjacent pairs of electrochemical cells are aligned antiparallel. In the 3 and 4 This can be seen from the fact that in the first pair of electrochemical cells 4 on the left side of the battery cell arrangement, the respective positive pole 5 points upwards. In the second pair from the left, the respective positive pole 5 points downwards, in the third pair it points upwards again and so on. Adjacent pairs of the electrochemical cells 4 are preferably in direct contact with one another. It is also advantageous if the two electrochemical cells 4 of each pair are also directly adjacent to one another. Each electrochemical cell 4 of a pair touches the other electrochemical cell 4 of the pair--geometrically speaking--on the outer casing. In addition, it touches a further electrochemical cell 4 of a first pair of neighbors on the outer casing and possibly also a cell of a second pair of neighbors, each on its outer circumference. The respective touches run linearly and parallel to each other. However, it is not necessary for the individual electrochemical cells 4 to touch each other directly; one or more spacers can also be provided, which keep the respective electrochemical cells at a distance from one another. Appropriate insulation must of course be provided.

The present example involves circular-cylindrical electrochemical cells whose longitudinal axes all run parallel to one another. In the top view of 4 the longitudinal axes occupy the corners of a grid with square elements. The longitudinal axes of the electrochemical cells 4 of two adjacent pairs lie exactly on the corner points of a square along the longitudinal axes in the plan view. In alternative embodiments, it can also be a rectangle. Since the individual electrochemical cells 4 are circular-cylindrical, there is a free space in the middle of the four electrochemical cells 4 . This free space is used here for exactly two cylindrical electrical capacitors 6, which are connected to one another in series and whose longitudinal axes are identical. The capacitors 6 are preferably double-layer capacitors, which also have a positive pole 7 and a negative pole (not visible in the figures).

How from the 3 and 4 As can be seen, the plus poles 7 of the pair of capacitors 6 on the left in the drawings each point upwards and are thus aligned in the same way as the electrochemical cells 4 of the adjacent pair of electrochemical cells. This pair of electrochemical cells 4 together with the adjacent pair of electrical capacitors 6 form a component group or module. The positive poles of all components in this group point in the same direction. In the present example, the positive poles 5, 7 of all components of the left component group in the 3 and 4 up. In the case of the immediately following component group consisting of two electrochemical cells 4 and two capacitors 6, the positive poles point downwards. For the next group of components, they point up again, and so on. Neighboring groups of components are therefore aligned antiparallel.

In the top view of 4 the longitudinal axes of two adjacent pairs of electrochemical cells 4 occupy the vertices of a square, as already described above. The common longitudinal axis of the two cylindrical electrical capacitors 6 connected in series is located in the center of the area of this square. The two coaxially aligned cylindrical capacitors 6 thus touch all four electrochemical cells 4 around them on their outer circumference. This results in a very compact battery cell arrangement that is spatially utilized to the maximum extent.

Simple contact plates 8 are provided here for electrical contact. As a rule, these contact plates 8 connect six poles of two adjacent, antiparallel groups of electrochemical cells 4 and electrical capacitors 6. For example, in 4 contact plates 8 shown in the middle have two negative poles (not shown) of electrochemical cells 4 and a negative pole of a capacitor of a component group with the positive poles 5 of two adjacent electrochemical cells 4 of the adjacent component group and a positive pole 7 of an associated capacitor 6. The contact plate 8 in 4 on the right connects corresponding six poles of the respective components. In contrast, the left contact plate 8 only connects the positive poles 5 and 7 of the first component group on the left. However, this contact plate 8 has a separate contact tongue 9 formed thereon, which represents the external contact (positive pole here) of the entire battery cell arrangement. In similar Licher way are the contact plates 8 on the underside of the battery cell assembly according to 3 educated. Here the contact plate 8 has a contact tongue 9 on the right-hand side as a negative pole for the entire battery cell arrangement. The battery cell arrangement can therefore be contacted with a few simple contact pads. In particular, the contact plates 8 can be flat, stamped metal plates.

As with the above embodiments, the electrochemical cells are preferably lithium ion cells. The electrical capacitors are preferably double layer capacitors. Since the upper voltage limit for double-layer capacitors is 2.3 to 2.6 V and the end-of-charge voltage of lithium-ion cells is around 4.2 to 4.35 V, the two series-connected double-layer capacitors are connected to the parallel lithium-ions in terms of voltage -Adapted cells of a component group. This not only results in an electrically very effective configuration, but also in a geometrically very compact shape of the battery cell arrangement 3.

In conventional battery cell arrangements, lithium-ion cells are often arranged in a paired configuration in a block set with no offset. This always creates a previously unused space in the middle between four cells. According to the invention, EDLC pairs, for example, are introduced exactly into this intermediate space, resulting in the above-described installation space advantage and existing battery packs hardly changing in their external geometry.

In the example of 4 are always two electrochemical cells 4 arranged side by side and connected in parallel. In principle, however, three, four, etc. electrochemical cells can also be connected in parallel and arranged in parallel. If there are several parallel groups of this kind, a regular grid similar to that of 4 . Here, too, respective capacitors, in particular double-layer capacitors, can be arranged in the spaces between the individual electrochemical cells 4 .

A major advantage of such battery cell arrangements is that the ratio of dielectric capacitances to electrochemical capacitances can be adjusted as desired. Second, the electrochemical capacity is not affected by the increase in dielectric capacity. Thirdly, previously unused space between the cells is used.

Reference List

1

power tool

2

battery pack

3

battery cell arrangement

4

electrochemical cell

5

positive pole

6

capacitor

7

positive pole

8th

contact plate

9

contact tongue

BMS

battery management system

C11

double layer capacitor

C12

double layer capacitor

C21

double layer capacitor

C22

double layer capacitor

M1

module

M2

module

50

main switch

S1

switching device

S2

switching device

Z1

lithium ion cell

Z2

lithium ion cell

Z3

lithium ion cell

Z4

lithium ion cell

Claims (5)

Battery cell arrangement (3) for a power tool (1). - several lithium-ion cells (Z1 to Z4), - several electric double layer capacitors (C11, C12, C21, C22) and - a battery management system (BMS) for controlling the plurality of lithium-ion cells (Z1 to Z4) and the plurality of electric double layer capacitors (C11, C12, C21, C22), wherein - Exactly two series-connected electric double-layer capacitors (C11, C12, C21, C22) are connected in parallel so as to form a module (M1, M2), - The battery cell arrangement has several such modules and - Each module (M1, M2) is individually controlled as a whole by the battery management system (BMS). Battery cell arrangement (3) after claim 1 , characterized in that the battery cell arrangement (3) has a plurality of modules (M1, M2) of the type mentioned and each of the plurality of modules (M1, M2) is connected separately via a respective switching device (S1, S2) to the battery management system (BMS). Battery cell arrangement (3) after claim 1 or 2 , characterized in that in the module (M1, M2) or in each of the several modules (M1, M2) in each case at least one further lithium-ion cell (Z1 to Z4) parallel to the respective pair of lithium-ion cells ( Z1 to Z4) is connected. Battery cell arrangement (3) according to one of the preceding claims, characterized in that a Zener diode is connected in parallel with each of the double-layer capacitors (C11, C12, C21, C22). Electric tool (1) with a battery cell arrangement (3) according to one of the preceding claims.

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