WO2023016607A1

WO2023016607A1 - Electrode, rechargeable battery, and manufacturing processes

Info

Publication number: WO2023016607A1
Application number: PCT/DE2022/100592
Authority: WO
Inventors: Benedikt STRAUB
Original assignee: RENA Technologies GmbH
Priority date: 2021-08-11
Filing date: 2022-08-11
Publication date: 2023-02-16

Abstract

The invention relates to an electrode (10), a rechargeable battery (100) and corresponding manufacturing processes. According to the invention, a silicon substrate (2) having a length (1) of 156 mm or more is provided, and a porous silicon layer (20) is formed on a bottom face (5) of the silicon substrate (2). In addition, a metal layer (30) is applied to the entire surface of the porous silicon layer (20). And finally, the porous silicon layer (20) with the metal layer (30) thereon is cut off a non-porous portion (40) of the silicon substrate (2).

Description

Electrode, accumulator and manufacturing process

The present invention relates to an electrode, in particular for an accumulator, a method for producing an electrode, the use of an electrode as an anode in an accumulator, two accumulators, in particular lithium-ion accumulators, and a method for producing an accumulator .

As a rule, small-format electrodes are required for the production of accumulators, in particular lithium-ion accumulators, as are used, for example, in mobile terminals. Such small-format electrodes based on silicon can easily be produced by appropriately dividing up a conventional silicon wafer, which may have been processed.

Since such silicon wafers are usually cut from an ingot, the maximum size of the electrodes is limited, namely to the ingot diameter or - with the usual square electrode formats - a length of -^1/2 x ingot diameter. With usual ingot diameters of approx. 200 mm, the maximum edge length of a square wafer is approx. 141mm .

However, larger electrodes are advantageous for certain applications, in particular for high capacities and power flows. For applications in the area of electric cars, for example, formats with 15×30 cm are preferred. In order to circumvent the limitation imposed by the wafer size, it was therefore proposed to transfer several silicon layers obtained from wafers by appropriate processing next to one another onto a metal foil. ferieren and to connect with this, for example, by gluing, laser welding or another joining process. In this case, the metal foil serves as a current conductor in an accumulator and can be electrically conductively connected to a conductor tab in an area that protrudes beyond the silicon foils.

Disadvantages of this procedure are the increased outlay for the precise arrangement of the silicon layers on the metal foil and the additional costs and the additional weight of the metal foil. At the same time, the metal foil also reduces the energy density of the accumulator. In addition, it has proven to be problematic to develop equipment which zize the precise arrangement of the silicon layers on the metal foil even at high speed, d. H . high throughput , can perform automated . However, the precise arrangement of the silicon layers is important, because otherwise the active material of the accumulator or a component thereof would be deposited in gaps between two silicon layers on the metal foil during operation of the accumulator. This can lead to dendrite growth, a short circuit in the accumulator and subsequent failure of the accumulator. In unfavorable cases, the accumulator could even catch fire.

Against this background, it is an object of the present invention to provide an improved electrode and an improved accumulator which, in particular, overcome the disadvantages mentioned.

This object is achieved by an electrode, a method for producing an electrode, use of an electrode as an anode, each of the two accumulators and a method for producing an accumulator according to the independent claims. Preferred embodiments are the subject of the independent claims and the following description.

An electrode according to a first aspect of the invention, in particular for an accumulator, for example a lithium-ion accumulator, has a porous silicon layer with a length of more than 156 mm and a metal layer arranged areally on the porous silicon layer. According to the invention, the porous silicon layer is formed in one piece.

One aspect of the invention is based on the approach of providing a one-piece, preferably monocrystalline, silicon layer whose extent in one dimension is more than 156 mm. The silicon layer can be, for example, a silicon layer obtained from a silicon substrate, which is or was cut lengthwise from a conventional silicon block, ie parallel to a longitudinal axis of the silicon block. In this case, the longitudinal axis can be understood to mean an axis which runs parallel to the direction of growth or crystallization of the silicon block. Silicon substrates obtained in this way can also be referred to as plates. This cutting parallel to the longitudinal axis into plates instead of conventionally perpendicular to the longitudinal axis into slices (wafers) basically allows silicon substrates with a length that essentially corresponds to the length of the silicon block - and correspondingly also silicon layers obtained from it. A silicon layer dimensioned in this way can advantageously be used as a large-format electrode, in particular in a large-format pouch or prismatic cell. If the silicon layer comes from a silicon block with a corresponding length, for example 1 m or more, it can even be used as a - suitably rolled up - electrode in a cylindrical cell or folding the electrode together with a separator and a further (counter) electrode is conceivable.

Such an electrode preferably comprises a metal layer arranged, in particular directly, on the silicon layer. In this respect, the electrode is expediently formed by a metal-coated silicon layer. The electrode can be produced, for example, by metallizing the silicon layer, for example by depositing a metal on the silicon layer. Conceivable metals here are, inter alia, nickel, copper and silver, with copper being or being preferred. Due to the metal layer or metallization, the electrode does not require any additional metal foil for current conduction. Rather, the metal layer can form a current collector. In this respect, it is expedient for the metal layer to be arranged areally on the silicon layer, ie for example to completely or at least almost completely cover the silicon layer. The electrode can then be electrically conductively connected directly to a conductor tab of a battery via the metal layer in a simple and space-saving manner.

It has proven to be expedient for the silicon layer to be porous, d. H . has pores. In principle, the pores can essentially have the same size or be subject to a certain size distribution. With the help of the pores, volume expansions in the silicon layer, such as those caused by the incorporation of atoms or molecules, can be compensated for. When using the electrode in a lithium-ion accumulator, the silicon layer can expand during the incorporation of lithium, for example into the cavities formed by the pores. This enables the silicon to withstand the volume expansion without being damaged, so that a long service life of the electrode can be achieved. Preferred embodiments of the invention and their developments are described below. Unless expressly excluded, these embodiments can each be combined with one another and with the aspects of the invention described below as desired.

In a preferred embodiment, the length of the porous silicon layer is more than 200 mm, in particular more than 300 mm. Such a silicon layer can be obtained, for example, by cutting it out of a silicon block with a corresponding minimum length, cutting parallel to the longitudinal axis of the silicon block. With the help of such a silicon layer, an electrode can be produced in formats of, for example, 15×60 cm to 20×60 cm.

In a further preferred embodiment, the porous silicon layer is completely covered by the metal layer. This enables homogeneous current dissipation over the entire surface of the silicon layer. An electrode in which the porous silicon layer is completely covered by the metal layer also allows the production of accumulators with high power flows.

In order to facilitate electrical contacting of the electrode, for example in such an accumulator, it is preferred that the metal layer has a section that does not cover the porous silicon layer. In other words, the metal layer can have a section that protrudes or protrudes beyond the silicon layer. survives , i . H . stands free . With the aid of a metal layer formed in this way, space can be provided in order to arrange a conductor tab on the electrode and to connect it in an electrically conductive manner. In a further preferred embodiment, the metal layer consists at least partially of copper. In particular, the metal layer can be formed by copper deposited on the porous silicon layer. The metallization of the silicon layer with copper can be done with less effort and cost than metallization with another metal l.

A particularly good adhesion of the metal layer to the silicon layer can be achieved by the copper layer protruding at least in sections into at least some of the pores. In this context one can also speak of embedding at least part of the copper layer in the porous silicon layer.

In a further preferred embodiment, the porous silicon layer has pores with a size of 10 nm or more. This makes it possible to ensure that the silicon has sufficiently large cavities available to withstand a volume expansion without being damaged.

Since very large pores, in particular of more than 1000 nm, can adversely affect the stability of the silicon layer, it is alternatively or additionally preferred that the porous silicon layer has pores with a size of 1000 nm or less.

In a further preferred embodiment, the metal layer has a layer thickness of 1 μm or more, preferably 2 μm or more. Such a minimum layer thickness of the metal layer is advantageous with regard to a manufacturing process of the electrode. Such a thickness of the metal layer can facilitate removing the metal layer together with the porous silicon layer from a silicon substrate. In order to make the electrode flexible and thus to be able to use it advantageously in different cell types, in particular to be able to fold and/or roll it up at least to a certain degree, it is preferred that the layer thickness of the copper layer is 30 μm, preferably 20 μm or less, preferably 12 pm or less, is .

To this extent, the electrode can be designed as a foil, in particular as a foil that can be rolled up. Cylindrical cells, for example, can also be realized with a film-like electrode whose length is at least 156 mm.

In a method according to a second aspect of the invention for producing an electrode, in particular an electrode according to the first aspect of the invention, a one-piece, preferably monocrystalline, silicon substrate with a length of 156 mm or more is provided. This preferably means that a silicon substrate is produced which extends over at least 156 mm in one dimension. At least one porous silicon layer is expediently formed on a substrate underside of the silicon substrate, for example by subjecting the substrate underside to an etching treatment. The underside of the substrate is preferably one of the two main sides of the substrate, d. H . one of the two largest sides in terms of area. It is conceivable, for example, for the underside of the substrate to be treated electrochemically, in particular electrochemically etched. This treatment of at least part of the silicon substrate, which forms a porous layer in the substrate, allows the stability of the future electrode, in particular an insensitivity to volume expansions, to be increased. In order to be able to derive current or to be able to connect the electrode to a potential, a metal layer is expediently applied over the entire surface of the at least one porous silicon layer. For example, a metal, in particular copper, can be deposited on the porous silicon layer. Finally, the at least one porous silicon layer with the metal layer arranged thereon is separated from the non-porosified part of the silicon substrate, as a result of which a flexible electrode can be obtained.

Because of the dimensioning, the large-format electrode produced in this way can also be used in large-format pouch or prismatic cells. If necessary, the electrode can even be rolled up and used in a cylindrical cell.

In addition, silicon substrates with a length of 156 mm or more can simplify the processing, in particular the electrochemical etching treatment for porosification of the substrate and/or the application of metal to the (porous) substrate. For example, in an inline system, longer etching tanks, in which a negative electrode is arranged and the etching process and the associated porosification take place, can be provided without the silicon substrate making the electrical contact (necessary for etching in the etching tank). to a side tank with a positive electrode placed therein. In this way, the ratio of “active” to “inactive” tank length, based on the length of a tank with a negative electrode and an adjacent tank with a positive electrode, in which no etching process takes place, can be improved. In this respect, the overall length of the system can also be reduced if necessary. In a preferred embodiment, the silicon substrate is provided with a length of 156 mm or more by cutting from a monocrystalline silicon block parallel to a longitudinal axis of the silicon block, the longitudinal axis preferably being parallel to the growth or Crystallization direction of the silicon in the silicon block runs. For use as an electrode base, it is appropriate that the silicon substrate has a <100> crystal orientation. In this respect, it is preferred that the silicon substrate is separated along a <100> plane of the silicon block. In principle, conventional techniques such as sawing or abrasive cutting can be used for cutting.

A silicon block within the meaning of the invention is preferably a cuboid silicon body. A silicon block can, for example, be cut out of an ingot, in particular by separating the two opposite ends, also known as "caps" (so-called "cropping") and lateral curves at right angles to one another (so-called squaring). In this respect, the silicon block is preferably made in this way An ingot is cut out so that it has a rectangular cross-sectional area. It should be ensured that the cutting planes are chosen correctly in order to enable silicon substrates with a <100> orientation. Overall, a silicon block cut out in this way allows easier further processing, in particular a low-cost one Cutting off the silicon substrate along a <100> plane running parallel to the longitudinal axis of the silicon block.

The ingot can advantageously be an ingot produced by the Czochralski process. With such a monocrystalline ingot, it is possible to a plurality of silicon substrates can be effectively produced with equally little effort and further processed in a corresponding system for electrode production with a high throughput.

Alternatively, the silicon substrate is fabricated by a continuous manufacturing process from a group of processes that includes Ribbon Growth on Substrate (RGS), String Ribbon, and Edge defined Film Growth (EEG). The advantage of this provision of the silicon substrate is the high efficiency in terms of material consumption, for example the avoidance of waste. However, in this way it is not possible to produce completely monocrystalline silicon substrates. These processes are therefore suitable when the electrode to be produced does not have to be monocrystalline.

Regardless of the method of provision, it is preferred that a silicon substrate is provided, the thickness of which is 1 mm or more, preferably 5 mm or more, in particular 10 mm or more. As a result, the mechanical stability of the silicon substrate can be ensured, in particular during the subsequent etching treatment for porosification and/or the deposition of metal. When cutting out of a silicon block, this thickness also has the advantage of less material loss.

In addition, a silicon substrate with such a thickness can have a lower electrical resistance compared to thinner substrates. As a result, the process homogeneity in the etching treatment for porosification can be improved and/or the etching speed can be increased by using higher current densities in this process.

A silicon substrate is particularly preferably provided, the thickness of which is 10 mm or more, preferably 20 mm or more, in particular 30 mm or more. Porous silicon layers with a metal layer arranged thereon can be produced and detached several times in succession on a silicon substrate with such a thickness. In this respect, once the silicon substrate has been provided, it can be “reused” after the porous silicon layer and the metal layer arranged on it have been detached.

In another preferred embodiment, the porous silicon layer is formed by etching. The silicon substrate is preferably transported along a transport direction over a plurality of treatment tanks arranged one behind the other in the transport direction in such a way that an underside of the substrate comes into contact with an etching medium in the treatment tank. The etching process can take place as a result of this bringing into contact. In this case, it is preferred that the etching process takes place electrochemically, since this allows a particularly good controllability of the etching process. In this respect, it is expedient that during the transport of the silicon substrate over the treatment tanks, electrodes arranged in the treatment tanks are placed alternately on a positive and a negative potential in the transport direction.

A potential of electrodes alternating in the transport direction can be understood in such a way that an electrode set to positive potential is followed in the transport direction by an electrode set to negative potential and the electrode set to negative potential is followed by another electrode set to positive potential in the transport direction. Such a change in potential can be repeated accordingly in the case of more than three treatment tanks following one another in the direction of transport. The same also applies if the first electrode is placed at positive potential. Electrochemical etching allows the silicon layer to become porous quickly and effectively.

In a further preferred embodiment, the metal layer is applied at least partially to the porous silicon layer by means of galvanic displacement. The silicon substrate is preferably transported along a transport direction via at least one treatment tank in such a way that the underside of the substrate comes into contact with a plating solution—which expediently contains the metal and a reducing substance for removing an oxide layer on the surface of the porous silicon layer—in the treatment tank. Since the galvanic displacement is a self-limiting process, a homogeneous and extensive deposition of the metal on the porous silicon layer can be achieved. For this purpose, a tank length of the treatment tank and/or the treatment time in the treatment tank is expediently chosen such that the entire surface of the porous silicon layer is metallized.

Alternatively, the metal layer can also be applied at least partially to the porous silicon layer by means of so-called "electroless plating". The silicon substrate is preferably transported along a transport direction over at least one treatment tank in such a way that s a substrate underside with an electrolyte - which expediently contains the metal and a reducing substance for reducing the metal to be deposited - comes into contact in the treatment tank.The metal reduced in this way in the tank can then be deposited automatically on the underside of the substrate.

In order to be able to further increase the thickness of the metal layer, in particular to 1 μm or more, preferably to 2 μm or more, it is preferred that the metal layer is at least partially in particular additionally, is applied to the porous silicon layer by means of electrochemical deposition. The silicon substrate is preferably transported along a transport direction via at least one treatment tank in such a way that at the same time a substrate underside comes into contact with a deposition solution in the treatment tank and a substrate top comes into contact with a running contact, while an electrical voltage is applied between an electrode in the treatment tank and the running contact . Electrochemical deposition metallization allows for precise control of the metallization process.

In a further preferred embodiment, the porous silicon layer with the metal layer arranged thereon is mechanically detached from the non-porous part of the silicon substrate. In particular, the porous silicon layer with the metal layer arranged thereon can be mechanically separated or lifted off from the non-porosified part of the silicon substrate. Such a mechanical detachment can represent a more energy-efficient variant, in particular compared to a thermal detachment. In addition, the material connections at the transition from the porous silicon layer to the non-porosified part of the silicon substrate can be loosened in a targeted manner with the mechanical detachment, so that little or no waste is produced.

Alternatively, however, it is also conceivable for the porous silicon layer with the metal layer arranged thereon to be thermally detached from the non-porous part of the silicon substrate. To do this, the silicon substrate or the metal layer can be heated up quickly, i . H . are subjected to a thermal shock, whereby the ziumschicht the porous Sili and the metal layer arranged thereon automatically separates from the non-porosi fi ed part of the silicon substrate or can at least be pulled off it with little effort and without great force.

The production of electrodes can be designed particularly ef fi ciently by the process being carried out again, the non-porosi fi- ed part of the silicon substrate obtained by detaching the porous silicon layer with the metal layer arranged thereon as new, preferably monocrystalline, silicon zium substrate with a length of 156 mm or more is provided. D. H . that the part of the silicon substrate remaining after detaching the porous silicon layer and the metal layer arranged on it is again subjected to an electrochemical etching treatment to produce a new porous silicon layer and a new metal layer can be applied flatly to this silicon layer, which can then be combined with the silicon zium layer is detached together. This procedure is preferably continued iteratively until the part of the silicon substrate that remains after detachment and is not porous has become too thin for further processing or pores are formed in the entire silicon substrate when the porous silicon layer is being formed. In this case, the last detachment step can be omitted.

According to a third aspect of the invention, the electrode according to the first aspect of the invention is used as an anode, in particular in an accumulator, in particular in a lithium-ion accumulator. By using such an electrode as an anode, the accumulator can be designed to be significantly more powerful than accumulators with conventional electrodes. At the same time, the operational reliability of the accumulator can be increased in this way. A rechargeable battery according to a fourth aspect of the invention, in particular a lithium-ion rechargeable battery, has an electrode according to the first aspect of the invention, resulting in the advantages described in the preceding paragraph.

In a preferred embodiment, the metal layer of the electrode is electrically conductively connected directly to a conductor tab. A conductor tab is preferably an electrical contact via which the anodes or cathodes of an accumulator can be connected to the corresponding pole of the accumulator. A direct electrically conductive connection between the electrode and the conductor tab is preferably a connection without intermediary components or lines. In this respect, the electrode can be connected to the collector tab without a dedicated metal foil that serves as a current collector. An electrode connected to the conductor tab in this way is expediently used as an anode or negative electrode or at least as part of such an anode. In this respect, anodes of the accumulator formed from the electrode and other electrodes of the same construction are preferably free of additional foils that act as current conductors. Compared to conventional accumulators with anodes that are connected to a conductor tab via such metal foils, weight can be saved and the energy density increased.

In a method according to a fifth aspect of the invention for producing a battery according to the fourth aspect of the invention, in particular a lithium-ion battery, the metal layer of the electrode is connected directly and electrically conductively to a conductor tab by welding, in particular ultrasonic welding or laser welding. The advantages described in the preceding paragraph result. Into the- In particular, this method can be used to provide an accumulator that can be operated safely and is more powerful than an accumulator with conventional electrodes.

In a preferred embodiment, the metal layer is electrically conductively connected, in particular welded, to the conductor tab in a section in which the metal layer covers the porous silicon layer, d. H . is arranged on the S ili ziumschicht. The production of the accumulator can be carried out with little effort, in particular without a section of the metal layer being free-standing, d. H . projecting beyond the porous silicon layer, must be formed.

Alternatively, the metal layer can be electrically conductively connected to the conductor tab in an area in which the metal layer does not cover the porous silicon layer, i. H . is not arranged on the silicon layer. In other words, the electrical connection to the conductor tab can be made in a section of the metal layer that is free of a silicon layer, for example in a section that protrudes or protrudes beyond the silicon layer. This can be advantageous with regard to the space available for arranging the conductor tab on the metal layer. In particular, this can facilitate the electrical connection, in particular welding, of the metal layer to the conductor tab.

To this end, the porous silicon layer in this section is expediently removed from the metal layer before the electrical connection is made to the conductor tab. As a result, space can be created in a targeted manner for arranging the conductor tab on the metal layer. For example, the porous silicon layer can be removed from the metal layer in said portion by one of a group of processes including laser ablation, dry etching and wet etching. This additional processing step may save a great deal of effort when electrically connecting the electrode to the conductor tab.

In a further preferred embodiment, the electrode (i) is combined with another identical electrode to form an anode in such a way that the metal layers lie flat on top of each other, (ii) several such anodes are stacked alternately with separators and cathodes, and (ii i) all Electrodes are electrically connected together to the conductor tab.

A summary within the meaning of the invention is preferably an arrangement of two components or groups of components in which the components or. Contact component groups, in particular over a large area. Optionally, the components can also be joined together at the contact points, for example connected to one another in a material-locking manner.

Alternating stacking within the meaning of the invention is preferably stacking such that an anode is separated from an adjacent cathode by a separator. In other words, an anode and a cathode are expediently located opposite one another in an alternating stack, with a separator being arranged between them. The metal layers of the electrodes serving as anodes can simplify the electrical connection of the electrodes stacked in this way to the collector tab due to their small spatial extent. By dispensing with additional (conventional) foils for dissipating current from the electrodes or anodes produce a compact building stack - and thus accumulator.

A rechargeable battery, in particular a lithium-ion rechargeable battery, according to a sixth aspect of the invention has an electrode which has a porous silicon layer and a metal layer arranged areally on the porous silicon layer. The electrode, in particular the porous silicon layer, can in principle have any format, in particular a length of 156 mm or less. According to the invention, the metal layer of the electrode is directly, i. H . directly, electrically conductively connected to a conductor tab. In other words, the metal layer of the electrode can serve as a current conductor. This allows the electrode to be connected to the collector tab without a dedicated metal foil serving as a current collector. As a result, installation space can be saved and the weight of the accumulator can be reduced.

In a preferred embodiment, the electrode is combined with another electrode of the same type to form an anode in such a way that the metal layers of the electrodes lie flat on top of one another. As a result, the two metal layers of the electrodes are preferably arranged between the two porous silicon layers. The anode formed in this way can consequently be arranged in a stack with cathodes and separators in a housing of the accumulator.

In a further preferred embodiment, the anode formed in this way is free of an additional foil that acts as a current collector. In other words, only the two metal layers are arranged between the porous silicon layers of the two electrodes. The invention is explained in more detail below with reference to figures. As far as expedient, elements that have the same effect are provided with the same reference characters. The invention is not limited to the exemplary embodiments shown in the figures - not even with regard to functional features. The previous description as well as the following description of the figures contain numerous features, some of which are combined into several in the dependent subclaims. However, the person skilled in the art will also consider these features, like all the other features disclosed above and in the following description of the figures, individually and put them together to form further meaningful combinations. In particular, all of the features mentioned are each individually and in any suitable combination with the electrode according to the first aspect of the invention, the method according to the second aspect of the invention, the use according to the third aspect of the invention, the accumulator according to the fourth aspect of the invention, can be combined with the method according to the fifth aspect of the invention and the accumulator according to the sixth aspect of the invention.

They show, at least partially schematically:

Fig. 1 shows an example of a large-scale silicon substrate;

Fig. 2 shows an example of a device for porosification of a silicon substrate;

Fig. 3 shows an example of a device for depositing a metal layer on a porous silicon layer;

Fig. FIG. 4 shows an example of a porous silicon layer 10 being detached from a non-porous part of a silicon substrate; FIG. Fig. 5 shows an example of an electrode with a porous silicon layer and a metal layer arranged thereon;

Fig. 6 shows an example of an accumulator; and

Fig. 7 another example of an accumulator.

FIG. 1 shows an example of a large-format silicon substrate 2 for the production of an electrode, which is preferably obtainable from a block 1 of silicon. "Large format" can be understood here as a silicon substrate 2, which has a substantially rectangular shape and a

length 1 of 156 mm or more. In other words, the large-scale silicon substrate 2 preferably extends at least 156 mm in at least one dimension, ie. H . the length of a total of four edges (two on a substrate top 6 and two on a substrate bottom 5) is preferably at least 156 mm.

A width b of the large-size silicon substrate 2 is preferably 100 mm or more, preferably 125 mm or more, particularly preferably 150 mm or more. In principle, however, narrower silicon substrates can also be used as a large-format silicon substrate 2 for producing an electrode.

A thickness d of the large-format silicon substrate 2 is preferably at least 1 mm, preferably at least 5 mm, more preferably at least 10 mm, most preferably at least 20 mm, particularly at least 30 mm. This thickness d can be used ziumsubstrat the Sili for the production of multiple electrodes by several times related to the Figures 2-5 described steps are performed. In principle, however, thinner or thicker silicon substrates can also be used as the large-format silicon substrate 2 for producing an electrode.

The large-format silicon substrate 2 is expediently monocrystalline, although in principle non-monocrystalline silicon substrates can also be used for electrode production. It is also expedient for a <100> crystal plane to run in the longitudinal direction of the large-format silicon substrate 2 .

The silicon substrate 2 with the dimensions described above is expediently separated from the preferably monocrystalline silicon block 1, for example sawed out or split off. It is expedient for the silicon block 1 to have a rectangular, in particular square cross-sectional area 4, at least before a first silicon substrate 2 is separated. Such a silicon block 1 can be obtained, for example, by cutting it out of a conventional (preferably monocrystalline) ingot, in particular by what is known as “cropping” (cutting off the two ends of the ingot, also known as caps) and/or “squaring” (cutting off the curves of the ingot).

In order to be able to obtain the large-sized silicon substrate 2, the silicon block 1 is expediently divided in the longitudinal direction. In other words, the silicon substrate 2 is expediently separated from the silicon block 1 along a parting plane 3 which preferably runs parallel to a longitudinal axis L of the silicon block 1 . After the silicon substrate 2 has been separated, the parting plane 3 can form a side face of the remaining silicon block 1 . The longitudinal axis L preferably runs parallel to a growth direction or crystallization direction of the silicon. That is, the ingot from which the silicon ingot 1 is made is preferably grown in a direction parallel to the longitudinal axis L .

The parting plane 3 preferably runs in a <100> plane. In principle, this is possible because conventional ingots have several <100> levels perpendicular to the direction of growth. The silicon substrate 2 separated from the silicon block 1 can therefore have the same crystal structure or crystal orientation as a conventional wafer cut transversely to the longitudinal axis L from the ingot.

A length 1 of the silicon substrate 2, i. H. the extension of the silicon substrate 2 in one dimension, namely in the longitudinal direction, can in principle correspond to the length of the silicon block 1 due to the longitudinal separation. Since ingots with lengths of more than 1 m can be produced without any problems, for example using the Czochralski method, the separated silicon substrate 2 can easily have a length 1 of 156 mm or more. Thus, the silicon substrate 2 is basically suitable for the production of a large-sized electrode.

The silicon substrate 2 provided in this way is expediently subsequently porosified for the production of the electrode, d. H. pores are produced in the silicon substrate 2 at least in sections, for example with a device shown in FIG.

FIG. 2 shows an example of a device 50 for porosifying a silicon substrate 2. Porosifying can take place by electrochemically etching the silicon substrate 2 on one side. Here, a transport device 51 be provided, which is set up to transport the silicon substrate 2 to be treated along a transport direction 52 . In the present example, the transport device 51 is designed as a roller conveyor with a plurality of transport rollers 53 .

The device 50 preferably comprises a plurality of treatment tanks 54 arranged one behind the other in the transport direction 52 , each of which is filled with an etching medium 55 and in each of which an electrode 56 is arranged. In FIG. 2, three treatment tanks 54 are shown as an example. In principle, the device 50 can have a larger or smaller number of treatment basins 54 .

The etching medium 55 is preferably an aqueous hydrogen fluoride solution. The etching medium 55 can optionally contain an additive and/or a surfactant. An electrical potential is preferably present at each of the electrodes 56, with the polarity of the electrodes 56 alternating in the transport direction 52.

The silicon substrate 2 is expediently transported with the aid of the transport device 51 along the transport direction 52 over the treatment tanks 54 , the silicon substrate 2 preferably only coming into contact with the etching medium 55 located in the treatment tanks 54 on its substrate underside 5 .

During the transport of the Sili ziumsubstrats 2 over the treatment tank 54, an electrochemical reaction can take place, in which it comes as a result of local inhomogeneities in the electric current density for the formation of etched peaks and etched valleys, which on the substrate underside 5 for the formation of Can lead to pores, so that a porous structure can arise on the substrate underside 5 .

The electrochemical reaction can be controlled via the electrical potential of the electrodes 56 which influences the electrical current density in the treatment tanks 54 . In addition, the reaction can be controlled by admixing an additive and/or a surfactant.

If an etching medium containing hydrogen fluoride is used as the etching medium 55, the following reaction can occur on the underside of the substrate 5: Si+6F~+4h ⁺ SiFe ² ~. The electric current provides defect electrons (h ⁺ ) on the surface of the silicon substrate 2 and the hydrogen fluoride forms hydrogen fluoride ions (F ~ ) in the solution.

Furthermore, the treatment device 50 between the treatment tanks 54 each includes an air knife, not shown in FIG.

The device 50 can be specifically adapted to the treatment of large format silicon substrates 2 . For example, given a length 1 of the silicon substrate 2 of 156 mm or more, longer treatment tanks 54 can be provided in the transport direction 52 . In particular, the treatment tanks 54, in which the electrodes 56 are or will be negatively polarized, can be made longer. Since the etching process takes place precisely in these basins 54 with negatively polarized electrodes 56, the ratio of “active” to “inactive” basin length, d. H . the ratio of the pool length of treatment pools 54 with negatively polarized electrodes 56 to the pool length of treatment lung basin 54 with positively polarized electrodes 56 . In principle, this allows the overall length of the device 50 to be reduced.

Alternatively or additionally, the treatment of silicon substrates 2 with a thickness d of 1 mm or more, preferably 5 mm or more, particularly preferably 10 mm or more, most preferably 20 mm or more, in particular 30 mm or more, allows the use of higher current densities than is possible when treating conventional substrates with thicknesses between 200 μm and 600 μm. This is due to the lower resistance that the thicker silicon substrates 2 have. The process homogeneity of the device 50 can thus also be improved as a result of the lower resistance.

In principle, the treatment in the device 50 can be repeated with the silicon substrate 2 turned upside down, so that the side surface of the substrate 2 shown in FIG. 2 as the substrate top 6 forms the substrate bottom 5 and is also porous.

FIG. 3 shows an example of a device 60 for applying a metal layer to a porous silicon substrate 2 , in particular to a porous silicon layer 20 of the silicon substrate 2 . The application can take place, for example, after the porosification of the silicon substrate 2 described in connection with FIG. 2, in particular inline. The application is preferably carried out by galvanic displacement on one side and optionally additionally by subsequent electrochemical deposition. For this purpose, a transport device 61 is vorzugswei se provided, which is adapted to the treated Sili ziumsubstrat 2 along a Transport direction 62 to be transported. In the present example, the transport device 61 is designed as a roller conveyor with a plurality of transport rollers 63 .

The device 60 , in particular for galvanic displacement, preferably comprises at least one treatment tank 64 which is filled with an aqueous deposition solution 65 . Optionally, the device 60, in particular for electrochemical deposition, can have at least one further treatment tank 66, which is also filled with the deposition solution 65 and in which an electrode 67 is arranged. The further basin 66 is expediently arranged downstream of the basin 64 in the transport direction 62 . A plurality of running contacts 68 , which can be designed as brush contacts, for example, are preferably provided above the further treatment tank 66 for electrical contacting of the substrate 2 .

In a first deposition step, a first part of the metal layer is deposited on the porous silicon layer 20 by means of galvanic displacement. In this deposition step, the silicon substrate 2 is brought into contact, preferably on its substrate underside 5, with the aqueous deposition solution 65, which contains, for example, hydrogen fluoride and a metal, in particular copper sulfate. The hydrogen fluoride can dissolve silicon dioxide from the substrate underside 5 of the silicon substrate 2, so that non-oxidized silicon remains on the substrate underside 5. Because of the chemical potential between the silicon and the metal, such as copper, the non-oxidized silicon is very attractive to the metal ions contained in the plating solution 65 .

Galvanic displacement is a self-limiting process. D. H . that the first deposition step stops by itself when the porous silicon layer 20 is complete is covered with metal. At the end of the first deposition step, said first part of the metal layer has preferably formed in such a way that the porous silicon layer 20 is embedded in the first part of the metal layer.

In a second deposition step, a second part of the metal layer can then be deposited on the first part of the metal layer by means of electrochemical deposition. In this case, the first part of the metal layer is expediently used as an electrically conductive seed layer for the formation of the second part of the metal layer.

In the second deposition step, the silicon substrate 2 (shown here with a broken line) is preferably wetted again with the deposition solution 65 on its substrate underside 5 above the further basin 66 . In this case, the silicon substrate 2 , in particular its substrate upper side 6 , is expediently electrically contacted by at least one of the running contacts 68 . In order to be able to advance the deposition of the metal in the deposition solution 65 further, an electrical voltage can be applied between the electrode 67 and the barrel contacts 68 . As a result of the electrical contacting of the substrate 2 via the running contacts 68 , the substrate 2 , in particular the first part of the metal layer (the seed layer) already deposited thereon, forms a counter-electrode. The electrode 67 is expediently connected to a positive potential and serves as an anode, while the silicon substrate 2, in particular the first part of the metal layer, is connected to a negative potential and serves as a cathode. The deposition solution 65 forms an electrolyte, in which case the metal cations dissolved therein can be deposited on the cathode (the silicon substrate 2, in particular the first part of the metal layer). The device 60 can be specifically adapted to the treatment of large format silicon substrates 2 . For example, given a length 1 of the silicon substrate 2 of 156 mm or more, treatment basins 64 , 66 that are longer in the transport direction 62 can be provided. Compared to conventional devices for galvanic metal deposition, the greater length 1 and greater thickness d of the large-format silicon substrate 2 eliminates the need to provide an overflow pot below the running contacts 68 in order to prevent the running contacts 68 from being wetted by the plating solution 65. In addition, due to the greater length 1 of the substrate 2, fewer running contacts 68 are necessary in the transport direction 62 in order to ensure that the same minimum number of running contacts 68 is always in contact with the substrate 2.

Basically - at least if the silicon substrate 2 is porous on both sides - the treatment in the device 60 can be repeated with the silicon substrate 2 turned over, so that the side of the substrate 2 shown in Figure 3 as the substrate top 6 forms the substrate bottom 5 and is also metallized .

FIG. 4 shows an example of a porous silicon layer 20 which is detached from a non-porous part 40 of a silicon substrate 2 and a metal layer 30 applied to the porous silicon layer 20 . The porous silicon layer 20 and the metal layer 30 applied thereon can be detached from the non-porous part 40 of the silicon substrate 2, for example after the deposition process for producing the metal layer 30 described in connection with FIG. 3, in particular inline. The porous silicon layer 20 and the metal layer 30 applied thereto are preferably mechanically detached, in particular separated, from the non-porous part 40 of the silicon substrate 2 . For this purpose, the porous silicon layer 20 is expediently formed in such a way that it has an increased porosity in a boundary region at the transition to the non-porosified part 40 of the silicon substrate 2 . This can be done, for example, in the method shown in FIG. A mechanical separating means 70 can then be used, for example a vacuum chuck 71 or belt, in order to pull off the porous silicon layer 20 with the metal layer 30 arranged thereon. The boundary area at the transition to the non-porous part 40 of the silicon substrate 2 can in this respect serve as a predetermined breaking point. If necessary, the removal can also be promoted by a thermal shock 72 .

In principle, two porous silicon layers 20, each with a metal layer 30 arranged thereon, can also be separated, for example if the silicon substrate 2 has previously been porous and metallized on both sides.

The detached porous silicon layer 20 with the metal layer 30 arranged thereon can—possibly after further processing—be used as an electrode, for example in an accumulator. The non-porous part 40 of the silicon substrate 2, on the other hand, can optionally be treated again with the device shown in FIG be metallized so that another electrode can be produced from it. An example of a further processing of the porous silicon layer 20 with the metal layer 30 arranged thereon is the incorporation of an active material , for example lithium, into the porous silicon layer 20 . Such storage can be electrochemical, for example in an electroplating bath in which a salt of the active material is dissolved or a voltage is applied between the porous silicon layer 20 with the metal layer 30 arranged thereon and a soluble anode containing the active material. The incorporation can take place via the non-metallized side of the porous silicon layer 20 after separation from the non-porous part 40 of the substrate 2 .

A result of further processing of the porous silicon layer 20, which can take place alternatively or additionally, for example for the incorporation of the active material, with the metal layer 30 arranged thereon is shown in FIG.

FIG. 5 shows an example of an electrode 10 with a porous silicon layer 20 and a metal layer 30 arranged thereon, with a section 31 of the metal layer 30 not covering the porous silicon layer 20, i. H . protrudes beyond the porous silicon layer 20 .

A free-standing or silicon layer-free section 31 of the metal layer 30 can be achieved, for example, by laser ablation of the porous silicon layer 20 in section 31 . Alternatively, however, the use of dry or wet etching methods is also conceivable. For example, one end of the porous silicon layer 20 with the metal layer 30 arranged thereon can be immersed in an etching bath which contains an etching medium with respect to which the metal layer 30 is inert. In this case, the extent of section 31 can easily be controlled via the depth of immersion in the etching bath. The creation of a free-standing section 31 of the metal layer 30—or, in other words, the exposure of the metal layer 30 in section 31—can substantially facilitate the integration of the electrode 10 into an accumulator, in particular the electrical connection of the metal layer 30 to a conductor tab.

The devices, means and method steps described in connection with FIGS. 2-5 can advantageously be provided or provided in a system, in particular inline. be performed . These devices, means and process steps or. the corresponding system are fundamentally suitable for the processing or manufacture of large-format electrodes with a length of more than 156 mm as well as small-format electrodes with a length of 156 mm or less. In this respect, the electrode 10 shown in FIG. 5 can be a large-format electrode that has a length of more than 156 mm. In principle, however, the electrode 10 can also be a smaller electrode, which has a length of 156 mm or less.

A system described in the previous paragraph can, for example, be a device for porosification, a device for forming a metal layer, a device for separating a porous silicon layer with a metal layer arranged thereon, a device for embedding an active material and/or a device for exposing a Have section of a metal layer. With such a system, a large-sized or small-sized electrode 10 can be manufactured. Correspondingly, FIGS. 2-5 can show steps of a method for producing an electrode 10 and/or a rechargeable battery. If the additional data shown in Figure 1 If the devices, means and method steps shown are taken into account, FIGS. 1-5 can show steps of a method for producing a large-format electrode 10 and/or a rechargeable battery with such a large-format electrode 10 .

FIG. 6 shows an example of a rechargeable battery 100 with an electrode 10 which has a porous silicon substrate with a length of 156 mm or more and a metal layer arranged thereon. The accumulator 100 can be a lithium ion accumulator with a cylindrical design.

The accumulator 100 includes a cylindrical housing 110 . In addition, the accumulator 100 includes a cathode 120 , an anode 130 and a separator 140 arranged between the cathode 120 and the anode 130 . The cathode 120 , the anode 130 and the separator 140 are each designed as a rolled-up foil and are arranged in the housing 110 of the accumulator 100 .

Two large-format electrodes 10 are expediently used as the anode 130 . In particular, two electrodes 10 can be used as anode 130, which was produced on the basis of the silicon substrate shown in FIG. 1 with the devices and/or method steps shown in FIGS. 2-5. The use of large format electrodes 10 allows the stack of cathode 120, anode 130 and separator 140 to be rolled up.

The two large-format electrodes 10 are arranged in such a way that the two metal layers lie flat on top of each other and are therefore arranged between the porous silicon layers. This arrangement is shown in detail in FIG FIG. 7 shows another example of a rechargeable battery 100 with a plurality of electrodes 10 . In this case, the accumulator 100 expediently has an alternative design with a rectangular base area in comparison to the accumulator shown in FIG. In principle, the electrodes 10 can be of large format, d. H . have a length of more than 156 mm. However, small-format electrodes 10 with a length of 156 mm or less are also conceivable.

In the alternative design, the accumulator 100 comprises a cuboid housing 110 . In addition, the rechargeable battery 100 comprises a plurality of cathodes 120 , a plurality of anodes 130 and separators 140 each arranged between a cathode 120 and an anode 130 . For reasons of clarity, only some of these components are provided with a reference sign.

The cathodes 120 , the anodes 130 and the separators 140 have a rectangular shape and are arranged stacked one on top of the other in a predetermined order in the housing 110 of the accumulator 100 .

The large-format electrodes 10 are expediently used as anodes 130 . In particular, two electrodes 10 each can be used as an anode 130, which were produced on the basis of the silicon substrate shown in FIG. 1 with the devices and/or process steps shown in FIGS. Alternatively, however, small-format electrodes 10 can also be used, which were produced using the devices and/or method steps shown in FIGS. 2-5.

Irrespective of the electrode format, the two electrodes 10 of an anode 130 are expediently arranged in such a way that their metal layers 30 lie flat on top of one another. the metal In this respect, layers 30 can be arranged between two porous silicon layers 20 . This arrangement allows the anodes 130 to be stacked in the predetermined order. The metal layers 30 are also well protected and can easily be electrically contacted outside of the stack.

The cathodes 120 expediently each have a current collector 121 , also referred to as an arrester. The current collectors 121 can be formed like foils. The current collectors 121 are made of aluminum, for example. The current collectors are preferably each coated on both sides with a cathode material 122 .

The anodes 130 are in particular stacked alternately with the separators 140 and the cathodes 120, so that each anode 130 is opposite a separator 140 on both sides, in particular adjoins a separator 140, and each cathode 120 is also opposite a separator 140 on both sides. in particular adjacent to a separator 140 .

The anodes 130, in particular each electrode 10, are electrically conductively connected via the metal layers 30 to a conductor tab 150 of the accumulator 100, for example welded, in particular ultrasonically or laser welded. For this purpose, each metal layer 30 of the electrodes 10 has a section 31 in which the porous silicon layer 20 is not covered by the metal layer 30 . In this section 31 the electrically conductive connection can be made without any problems during the production of the accumulator 100 .

Similarly, the cathodes 120 are electrically conductively connected via the current collectors 121 to a conductor tab 151 of the accumulator 100, for example welded, in particular ultrasonically or laser welded. In order to easily connect both the current collectors 121 and the sections 31 to the arrester tabs 150 and 151 are protruding from the stack

Sections 123 of the current collectors 121 and the sections 31 are expediently designed as small flags which are offset perpendicular to the plane of the figure. In the example shown in FIG. 7, the sections 123 are arranged perpendicularly to the plane of the figure behind the sections 31, so that the conductor tabs 150 and 151 can in principle also run at the same distance from the stack.

reference character list

1 silicon block

2 silicon substrate

3 parting plane

4 cross-sectional area

5 substrate underside

6 substrate top

10 electrode

20 porous silicon layer

30 metal layer

31 section

40 non-porosi f i ed part of the silicon substrate

50 device for porosification

51 transport device

52 transport direction

53 transport rollers

54 treatment pools

55 etching medium

56 electrode

57 gas flow

60 Device for applying a metal layer

61 transport device

62 transport direction

63 transport rollers

64 treatment pools

65 plating solution

66 additional treatment tanks

67 electrode

68 running contact 70 release agents

71 vacuum chuck

72 thermal shock

100 accumulator

110 housing

120 cathode

121 current collector

122 cathode material

123 section

130 anode

140 separator

150 arrester tab

151 arrester tab

1 length b width d thickness

L longitudinal axis

Claims

38

patent claims

1. Electrode (10), in particular for an accumulator (100), having a porous silicon layer (20) with a length (1) of more than 156 mm and a metal layer (30) arranged flat on the porous silicon layer (20), d a d u r c h g e n n n z e i c h n e t that the porous silicon layer (20) is formed in one piece.

2. Electrode (10) according to claim 1, d a d u r c h g e k e n n z e i c h n e t that the length (1) of the porous silicon layer (20) is more than 200 mm, in particular more than 300 mm.

3. Electrode (10) according to claim 1 or 2, d a d u r c h g e k e n n z e i c h n e t that the porous silicon layer (20) is completely covered by the metal layer (30).

4. Electrode (10) according to one of the preceding claims, d a d u r c h g e k e n n z e i c h n e t that the metal layer (30) has a section (31) which does not cover the porous silicon layer (20).

5. Electrode (10) according to one of the preceding claims, d a d u r c h g e k e n n z e i c h n e t that the metal layer (30) consists at least partially of copper.

6. Electrode (10) according to any one of the preceding claims, characterized in that the porous silicon layer (20) has pores with a size of 10 nm or more and/or of 1000 nm or less. Electrode (10) according to one of the preceding claims, characterized in that the metal layer (30) has a layer thickness of 1 pm or more, in particular 2 pm or more, and / or 30 pm or less, preferably 20 pm or less, in particular of 12 pm or less. Electrode (10) according to one of the preceding claims, characterized in that the electrode (10) is designed as a film, in particular as a rollable film. Method for producing an electrode (10), in particular according to one of the preceding claims, having

- Providing a silicon substrate (2) with a length (1) of 156 mm or more,

- Forming at least one porous silicon layer (20) on a substrate underside (5) of the silicon substrate (2),

- Areal application of a metal layer (30) to the at least one porous silicon layer (20), and

- Detaching the at least one porous silicon layer (20) with the metal layer (30) arranged thereon from the non-porosif ized part (40) of the silicon substrate (2). Method according to Claim 9, characterized in that the silicon substrate (2) is separated from a monocrystalline silicon block (1) along a <100> plane running parallel to a longitudinal axis (L) of the silicon block (1). Method according to Claim 10, characterized in that the silicon block (1) is cut out of an ingot, preferably produced by the Czochralski process, in such a way that it has a rectangular cross-sectional area (4) transverse to the longitudinal axis (L). Method according to Claim 9, characterized in that the silicon substrate (2) is manufactured by a continuous manufacturing process from a group of processes which includes Ribbon Growth on Substrate, String Ribbon and Edge Defined Film Growth. Method according to one of Claims 9 to 12, characterized in that a silicon substrate (2) is provided, the thickness (d) of which is 1 mm or more, preferably 5 mm or more, in particular 10 mm or more. Method according to one of Claims 9 to 13, characterized in that a silicon substrate (2) is provided, the thickness (d) of which is 10 mm or more, preferably 20 mm or more, in particular 30 mm or more. Method according to one of Claims 9 to 14, characterized in that the porous silicon layer (20) is formed by means of electrochemical etching, in which the silicon substrate (2) is etched along a transport direction (52) over a plurality of treatment tanks (54 ) is transported that one Substrate underside (5) comes into contact with an etching medium (55) in the treatment tank (54), while electrodes (56) arranged in the treatment tank (54) are alternately placed at a positive and negative potential in the transport direction (52). Method according to one of Claims 9 to 15, characterized in that the metal layer (30) is applied at least partially to the porous silicon layer (20) by means of galvanic displacement or electroless plating, in which the silicon substrate (2) moves along a transport direction (62 ) is transported via at least one treatment tank (64) such that a substrate underside (5) comes into contact with a deposition solution (65) or an electrolyte in the treatment tank (64). Method according to one of Claims 9 to 16, characterized in that the metal layer (30) is applied at least partially to the porous silicon layer (20) by means of electrochemical deposition, in which the silicon substrate (2) is transported along a transport direction (62) via at least one other treatment tank (66) is transported so that at the same time a substrate underside (5) comes into contact with a plating solution (65) in the treatment tank (66) and a substrate top side (6) comes into contact with a running contact (68), while between an electrode (67) in the treatment tank (66) and the running contact (68) an electrical voltage is applied. Method according to one of claims 9 to 17, characterized in that that the porous silicon layer (20) with the metal layer (30) arranged thereon is mechanically detached from the non-porosified part (40) of the silicon substrate (2).

19. The method according to claim 18, d a d u r c h g e k e n n z e i c h n e t that the method is carried out again, with the non-porous part (40) of the silicon substrate (2) obtained by detaching the porous silicon layer (20) with the metal layer (30) arranged thereon as new silicon substrate (2) with a length (1) of 156 mm or more is provided.

20. Use of an electrode (10) according to any one of claims 1 to 8 as an anode (130), in particular in an accumulator (100).

21. Accumulator (100), in particular lithium-ion accumulator, with an electrode (10) according to one of claims 1 to 8.

22. Accumulator (100) according to claim 21, d a d u r c h g e k e n n z e i c h n e t that the metal layer (30) of the electrode (10) is electrically conductively connected directly to a conductor tab (150).

23. Accumulator (100) according to any one of claims 21 or 22, characterized in that anodes (130) of the accumulator (100), which are formed from the electrode (10) and other identical electrodes, are free of additional, acting as a current collector slides. 43 Method for producing an accumulator (100) according to one of claims 21 to 23, wherein the metal layer (30) of the electrode (10) is directly and electrically conductively connected to a conductor tab (150) by welding, in particular ultrasonic welding or laser welding. Method according to Claim 24, characterized in that the metal layer (30) is electrically conductively connected to the conductor tab (150) in a section (31) in which the metal layer (30) covers the porous silicon layer (20). Method according to Claim 24, characterized in that the metal layer (30) is electrically conductively connected to the conductor tab (150) in a section (31) in which the metal layer (30) does not cover the porous silicon layer (20). Method according to Claim 26, characterized in that the porous silicon layer (20) in the section (31) is removed from the metal layer (30) before the electrical connection to the conductor tab (150). A method according to claim 27, characterized in that the porous silicon layer (20) is removed from the metal layer (30) by one of a group of processes including laser ablation, dry etching and wet etching. 44

29. The method according to any one of claims 24 to 28, d a d u r c h g e k e n n z e i c h n e t that the electrode (10) is combined with another electrode of the same construction to form an anode (130) in such a way that the metal layers (30) lie flat on top of each other, and several such anodes (130 ) are stacked alternately with separators (140) and cathodes (120), and all electrodes (10) are electrically conductively connected together to the conductor tab (150).

30. Accumulator (100), in particular a lithium-ion accumulator, with an electrode which has a porous silicon layer (20) and a metal layer (30) arranged areally on the porous silicon layer (20) d a d u r c h g e n n n s e i c h n e t that the metal layer (30) of the Electrode is electrically conductively connected directly to a conductor tab (150).

31. Accumulator (100) according to claim 30, d a d u r c h g e k e n n z e i c h n e t that the electrode is combined with another electrode of the same type to form an anode (130) in such a way that the metal layers (30) of the electrodes lie flat on top of each other.

32. Accumulator according to claim 31, d a d u r c h g e k e n n z e i c h n e t that the anode (130) formed in this way is free of an additional foil acting as a current collector.