Secondary electrochemical lithium-ion cell

Abstract

To provide a lithium-ion cell in which losses of mobile lithium can be compensated.SOLUTION: A secondary electrochemical lithium-ion cell includes at least one composite electrode as a negative electrode 10, the composite electrode comprising at least one anode current collector 12 and at least one electrochemically active component capable of intercalating and deintercalating lithium ions. The lithium-ion cell further includes at least one composite electrode as a positive electrode 20, the composite electrode comprising at least one cathode current collector 22 and at least one electrochemically active component capable of intercalating and deintercalating lithium ions. Further, the negative electrode 10 and / or the positive electrode 20 has at least one region 11 in which the anode current collector 12 and / or the cathode current collector 22 is at least partly free of the electrochemically active components, the region 11 being formed as a lithium reserve.SELECTED DRAWING: Figure 2

Description

[Technical field]

[0001] The present invention relates to a lithium ion secondary electrochemical cell, a coil or stack for a lithium ion secondary electrochemical cell formed from an anode and a cathode, and a method for manufacturing such a coil or stack, as well as a method for manufacturing a lithium ion secondary electrochemical cell. [Background technology]

[0002] Electrochemical cells can convert stored chemical energy into electrical energy by redox reactions. Electrochemical cells generally contain a positive electrode and a negative electrode. During discharge, electrons are released at the negative electrode as a result of an oxidation process. This results in an electronic current that can be used by external consumers, and thus the electrochemical cell acts as an energy supplier. At the same time, an ionic current is generated inside the cell corresponding to the electrode reactions. This ionic current is made possible by an ion-conducting electrolyte.

[0003] If the discharge is reversible, the cell is called a secondary cell, meaning that the conversion of chemical energy into electrical energy that occurs during discharge can be reversed, thus allowing the cell to be recharged. The conventional designation of the negative electrode as the anode and the positive electrode as the cathode in secondary cells refers to the discharge function of the electrochemical cell.

[0004] The widely used lithium-ion cells are based on the use of lithium, which can be transported in ionic form between the electrodes of the cell. One of the characteristics of lithium-ion cells is their relatively high energy density. The negative and positive electrodes of lithium-ion cells are usually formed from what are known as composite electrodes, which contain electrochemically active components as well as electrochemically inactive components.

[0005] Suitable as electrochemically active components (active materials) are in principle all materials capable of absorbing and releasing lithium ions. In this case, particles based on carbon, for example graphitic carbon, are often used as the negative electrode. Other non-graphitic carbon materials suitable for lithium intercalation can also be used. Furthermore, metallic and semi-metallic materials capable of alloying with lithium can also be used. For example, the elements tin, antimony and silicon can form intermetallic phases with lithium. An example of an active material that can be used as the positive electrode is lithium cobalt oxide (LiCoO 2 ), lithium manganate (LiMn 2 O 4 ), or lithium iron phosphate (LiFePO 4 ) or derivatives thereof. The electrochemically active material is usually present in the electrode in particulate form.

[0006] As electrochemically inactive components, the composite electrode generally comprises a planar and / or tape-shaped current collector, e.g. a metal foil, on which the active material is coated. The negative current collector (anode current collector) can be made, for example, of copper or nickel, and the positive current collector (cathode current collector) can be made, for example, of aluminum. In addition, the electrode can comprise an electrode binder, e.g. polyvinylidene fluoride (PVDF) or another polymer, which ensures the mechanical stability of the electrode and also ensures the adhesion of the active material to the current collector. In addition, the electrode can comprise a conductivity improving additive and other additives.

[0007] A typical electrolyte solution for lithium-ion cells is, for example, lithium hexafluorophosphate (LiPF 6 ) in organic solvents (e.g. ethers and esters of carbonic acid).

[0008] In the manufacture of lithium-ion cells, the composite electrodes are often fabricated into a stack or coil, with the negative and positive electrodes separated from each other in the stack or coil by separators.

[0009] For electrical contact of the negative and positive electrodes, current conductors can be provided which are connected to the current collectors, for example by welding. Direct contact of the current collectors with the housing elements of the lithium-ion cell is also an option.

[0010] The functioning of lithium-ion cells is based on the presence of sufficient mobile lithium ions (mobile lithium) to compensate for the current being extracted by migrating between the anode and the cathode (i.e. between the negative and positive electrodes). In the context of this application, mobile lithium should be understood to mean that lithium is available for the intercalation and deintercalation processes in the electrodes during the discharge and charge processes in lithium-ion cells, or that it is activatable for this purpose. In the course of the discharge and charge processes that occur in lithium-ion cells, a reduction in mobile lithium occurs over time. These reductions occur as a result of various side reactions that are generally unavoidable. A reduction in mobile lithium occurs even during the very first charge / discharge cycle of a lithium-ion cell. During this first charge / discharge cycle, a surface layer is usually formed on the surface of the electrochemically active components on the negative electrode. This surface layer is called the solid electrolyte interphase (SEI) and usually consists mainly of electrolyte decomposition products and a certain amount of lithium, which is tightly bound in this layer. The reduction in mobile lithium associated with this process can range from 10% to 35%. Subsequent charge / discharge cycles experience much less depletion, but the continued depletion of mobile lithium continues to reduce the capacity and performance of conventional lithium-ion cells over time.

[0011] Various methods are already known for compensating for the loss of mobile lithium that occurs. For example, EP 2 486 620 B1 describes a lithium-ion cell with improved aging behavior, in which the capacity of the negative electrode to absorb lithium is greater than that of the positive electrode and at the same time greater with respect to the total amount of mobile lithium. At the same time, a certain amount of mobile lithium is present in the cell that exceeds the capacity of the positive electrode to absorb lithium.

[0012] EP 3 255 714 A1 discloses an electrochemical cell having a lithium reservoir, which is provided in the cell in the form of a lithium alloy, and which can be arranged, for example, between an electrode and the housing of the cell.

[0013] EP 2 372 732 A1 describes a spirally wound coil having negative and positive electrodes for an electrochemical lithium-ion cell, in which there is a source of lithium ions separated from the positive and negative electrodes by a separator so as not to come into contact with the electrodes. Summary of the Invention [Problem to be solved by the invention]

[0014] On the other hand, it is an object of the present invention to provide an improved lithium-ion cell capable of compensating for the loss of mobile lithium in a particularly advantageous manner, which should prevent or slow down the cell aging process in order to achieve a particularly long cell service life. [Means for solving the problem]

[0015] This object is achieved by a lithium-ion secondary electrochemical cell and by a coil or stack for a lithium-ion secondary electrochemical cell as indicated in the independent claims. Furthermore, this object is achieved by a method for producing a coil or stack of this kind and by a method for producing an electrochemical lithium-ion cell according to the further independent claims. Preferred configurations of the lithium-ion cell, the coil or stack and the production method become apparent from the dependent claims.

[0016] The lithium-ion cell of the present invention is always characterized by the following features: a. It comprises at least one composite electrode as a negative electrode, which comprises at least one anode current collector and at least one electrochemically active component capable of intercalating and deintercalating lithium ions. b. It comprises at least one composite electrode as a positive electrode, which comprises at least one cathode current collector and at least one electrochemically active component capable of intercalating and deintercalating lithium ions.

[0017] It is characterised in particular by the following features: c. The negative electrode and / or positive electrode have at least one region in which the anode current collector and / or cathode current collector are at least partially free of electrochemically active component, this region being formed as a lithium reserve.

[0018] Thus, the negative and / or positive electrodes comprise a current collector having at least one area covered with an electrochemically active component and at least one other area free of this component and formed as a lithium reserve.

[0019] The area defined as the lithium reserve preferably does not contain any electrochemically active component.

[0020] This region is preferably also free of the aforementioned electrode binders and / or the aforementioned conductivity improving additives.

[0021] In this context, lithium reserve means that this region of the negative electrode and / or positive electrode has a certain amount of metallic lithium and / or lithium-containing material. During the service life of the lithium-ion cell of the present invention, the lithium stored in this region serves as a lithium reservoir, which can be released as mobile lithium in ionic form and subsequently available for the charge / discharge cycle of the lithium-ion cell. This can significantly improve the service life of the lithium-ion cell, since the aging process based on the reduction of mobile lithium is compensated by the lithium reserve.

[0022] In all cases, the metallic lithium or lithium-containing material of the lithium reserve is substantially different from the electrochemically active component, which typically also contains lithium, possibly in ionic form (see below). For example, the lithium reservoir preferably does not contain any lithium-containing alloys or compounds that are constituents of the electrochemically active component.

[0023] The arrangement of the lithium reserve directly on the current collector, i.e. to some extent in the negative and / or positive electrode, is particularly advantageous, in particular with regard to optimal utilization of the geometry of the lithium-ion cell. The arrangement of the lithium reserve directly on the area of ​​the current collector that does not contain electrochemically active components allows optimal utilization of the space in the lithium-ion cell, without the lithium reserve taking up additional space in the lithium-ion cell. The area of ​​the lithium reserve can be selected in such a way that there is no geometrical clash with other elements of the lithium-ion cell. For example, the arrangement of the lithium reserve as described in EP 2 372 732 A1 may increase the risk of short circuits caused by the lithium reserve coming into contact with the ends of electrodes of opposite polarity. The formation of the lithium reserve according to the invention can be carried out already during the manufacture of the electrodes. This means that a separate step for the formation and arrangement of the reserve at a later stage is not necessary.

[0024] The anode and cathode current collectors of the negative and positive electrodes, respectively, are preferably planar metal substrates, such as metal foils or metal foams or metal nets or metal meshes or metallized nonwoven fabrics. Suitable metals for the anode current collectors are, for example, copper or nickel or another conductive material. Suitable metals for the cathode current collectors are, for example, aluminum or another conductive material.

[0025] As electrochemically active components of the negative and positive electrodes, materials well known to those skilled in the art can be used. Particularly suitable for use as negative electrodes are carbon-based particles, such as graphitic carbon or non-graphitic carbon materials capable of intercalating lithium, preferably also in particulate form. Alternatively or in addition, metal and semi-metallic materials capable of alloying with lithium can also be used, such as the elements tin, antimony, and silicon, capable of forming intermetallic phases with lithium. These materials are also preferably used in particulate form. In the case of the positive electrode, the electrochemically active components can be, for example, lithium-metal oxide compounds and lithium-metal phosphate compounds, such as LiCoO 2 and LiFePO 4 In particular, the molecular formula LiNi x Mn y Co z O 2 Lithium nickel manganese cobalt oxide (NMC), with the molecular formula LiMn 2 O 4 Lithium manganese spinel (LMO), with the empirical formula LiNi x Co y Al z O 2 Lithium nickel cobalt aluminum oxide (NCA), having the empirical formula Li, is also very suitable. 1.11 (Ni 0.40 Mn 0.39 Co 0.16 Al 0.05 ) 0.89 O 2 Lithium nickel manganese cobalt aluminum oxide (NMCA), or Li1+x It is also possible to use MO compounds and / or mixtures of the above materials.

[0026] The particulate electrochemically active components are preferably embedded in a matrix of the aforementioned electrode binder, with adjacent particles in the matrix preferably in direct contact with one another.

[0027] When structured current collectors are used as anode current collectors and / or cathode current collectors, for example perforated or otherwise apertured metal foils, or metal nets or metal meshes or metal or metallized nonwovens, or metal foams with open cells are particularly preferred, which is particularly advantageous since lithium ions subsequently released from the lithium reserve can migrate particularly easily throughout the lithium-ion cell and be distributed evenly throughout the lithium-ion cell.

[0028] For optimal distribution of lithium ions in the cell, the cells of the invention are particularly preferably A tape-shaped metal foil having a thickness in the range of 4 μm to 30 μm and having first and second longitudinal ends and two terminal ends as an anode current collector; A tape-shaped metal foil having a thickness in the range of 4 μm to 30 μm and having first and second longitudinal ends and two terminal ends as a cathode current collector; Including, the anode current collector having a tape-shaped main region having a layer of negative electrode material and a free end strip extending along a first longitudinal edge and free of electrode material; and / or The cathode current collector has a tape-shaped main region having a layer of positive electrode material and a free end strip extending along a first longitudinal edge having no electrode material.

[0029] Both the anode and cathode current collectors preferably have tape-like main regions and free end strips.

[0030] The tape-shaped main area of ​​the anode current collector and / or the tape-shaped main area of ​​the cathode current collector, particularly preferably the tape-shaped main area of ​​the anode current collector and the tape-shaped main area of ​​the cathode current collector, preferably have a large number of openings.

[0031] As a result of the large number of openings, the volume and weight of the current collector is reduced, which allows more active material to be introduced into the cell, thus significantly increasing the energy density of the cell. Energy density increases up to the double-digit percentage range can be realized in this manner.

[0032] In a particularly preferred configuration, the cell of the invention is characterized in that it has at least one of the further features a. and b. immediately below: The openings in the main area are circular or square holes, particularly punched or drilled holes. b. The main area of ​​the anode current collector and / or the cathode current collector is perforated, in particular by circular hole perforations or elongated hole perforations.

[0033] In some preferred embodiments, the openings are introduced into the tape-like main region by a laser.

[0034] The shape of the openings is not fundamental to the invention, what is important is that the introduction of the openings reduces the mass of the current collector and allows the openings to be filled with active material, thus providing more space for the active material therein.

[0035] On the other hand, it can be very advantageous to introduce the openings so that their maximum diameter is not too large: the openings should preferably be no more than twice the thickness of the layer of electrode material on each current collector.

[0036] In a particularly preferred configuration, the cell of the invention is characterized in that it has the further feature a. immediately below: a. The openings in the current collector, especially in the main region, have a diameter in the range of 1 μm to 3000 μm.

[0037] Within this preferred range, the diameter is more preferably in the range of 10 μm to 2000 μm, more preferably in the range of 10 μm to 1000 μm, and particularly preferably in the range of 50 μm to 250 μm.

[0038] It is particularly preferred if the cell of the invention has at least one of the further features a. and b. immediately below: a. Over at least a portion of a major area, the anode current collector and / or cathode current collector has a lower weight per unit area than the associated free end strip. b. In the free end strips, the anode current collector and / or cathode current collector have no perforations or have fewer perforations per unit area than in the main area.

[0039] It is particularly preferred if the immediately above features a. and b. are realised in combination with one another.

[0040] The anode and cathode current collectors each define a major area on the side of the first longitudinal end by free end strips, and preferably each of the anode and cathode current collectors includes a free end strip along both longitudinal ends.

[0041] The openings characterize the main region, in other words the boundary between the main region and the free end strip corresponds to the transition between the opening and non-opening regions.

[0042] The openings are preferably substantially uniformly distributed across the major area.

[0043] In further particularly preferred embodiments, the cell of the invention is characterized in that it has at least one of the features a. to c. immediately below: a. The weight per unit area of ​​the anode current collector and / or cathode current collector is reduced in the major area by 5% to 80% less than the weight per unit area of ​​the respective current collector in the free end strip. b. In the major area, the current collector has a perforated area in the range of 5% to 80%. c. In the main area, the current collector is 20N / mm 2 ~250N / mm 2 It has a tensile strength of

[0044] The perforated area, also commonly referred to as the free cross section, can be determined according to ISO 7806-1983. The tensile strength of the current collector in the main area is lower than that of a current collector without openings. This can be determined according to DIN EN ISO 527 Part 3.

[0045] It is preferred that the anode and cathode current collectors be of the same or similar design with respect to apertures, with added improvements in energy density achievable in each case.

[0046] In addition to the components already mentioned, the lithium-ion secondary electrochemical cell of the present invention advantageously also comprises a housing which preferably surrounds the electrodes in an air-tight and / or liquid-tight manner.

[0047] In some preferred configurations, the cell includes an electrical conductor for the electrical contact of the negative electrode and / or an electrical conductor for the electrical contact of the positive electrode to allow electrical contact of the electrodes. One end of these conductors can be welded to the anode or cathode current collector. The other end can be welded to a housing element or can exit the housing through a terminal bushing.

[0048] In another embodiment, there may be direct contact between the electrode and the housing or part of the housing. This is particularly preferred and will be treated separately.

[0049] Furthermore, the lithium-ion cell advantageously comprises at least one separator for separating the positive and negative electrodes in a manner known per se.

[0050] Furthermore, the cell comprises at least one electrolyte, which is conventional per se, in particular at least one lithium salt present dissolved in an organic solvent, for example in a mixture of organic carbonates, such as an electrolyte based on lithium hexafluorophosphate. In the construction of the lithium-ion cell of the invention, it is particularly advantageous if the region containing the lithium reserve is in ionic contact with the electrolyte, so that the lithium ions released from the lithium reserve are directly available for the electrochemical processes in the cell.

[0051] By integrating a lithium reserve into the electrode coil or electrode stack, the cycle life of the lithium-ion cell can be extended and, particularly preferably, the energy density can also be increased. This is because the aging process that limits the useful life of a lithium-ion cell is generally caused by the reduction of mobile lithium. By introducing a lithium reserve onto the uncoated areas (i.e. areas not coated with electrochemically active components) of the negative electrode and / or the positive electrode, preferably only the negative electrode, this lithium reserve, or the corresponding prelithiation of these areas, can act as a reservoir of mobile lithium over the cycle life of the lithium-ion cell.

[0052] Furthermore, especially in the case of silicon-containing negative electrodes, the lithium-ion cells of the present invention generally require less cathode material, which usually serves as the lithium source, and therefore the energy density can also be increased, and therefore the cost can be reduced. Therefore, the negative electrode is particularly preferably a silicon-containing electrode or a composite electrode coated with a silicon-containing electrochemically active material.

[0053] In one preferred further development, the lithium-ion cell of the invention is characterized in that it has at least one of the following characteristics a. to c.: a. A negative electrode formed as a composite electrode and a positive electrode formed as a composite electrode are each in the form of a tape. b. The negative and positive electrodes are separated from each other by a separator. c. The negative and positive poles are components of a coil.

[0054] It is particularly preferable that the immediately above features a to c are realized in combination with one another.

[0055] In this particularly preferred configuration, the negative and positive electrodes and the separator form a composite unit, which is processed into a coil, in particular a helical coil. Such a coil is preferably of cylindrical design and has two terminal, preferably flat, end faces. Providing the electrodes in the form of such a coil allows a particularly advantageous arrangement of the electrodes in a cylindrical housing.

[0056] In one preferred further development, the lithium-ion cell of the invention is characterized in that it has at least one of the characteristics a. and b. immediately below: a. The above-mentioned region is disposed at the longitudinal end of the tape-shaped negative electrode and / or tape-shaped positive electrode. b. The region containing the lithium reserve forms the outside of the coil and / or defines a void in the center of the coil.

[0057] It is particularly preferred if the immediately above features a. and b. are realised in combination with one another.

[0058] The outside of the coil may be formed, for example, by the negative electrode. The area containing the lithium reserve may occupy a part of this outside or the entire outside of the coil, whereby the area of ​​the lithium reserve is preferably applied only to the outside of the anode current collector and not to the inside of the anode current collector, so that the inside of the electrode of the external coil is coated with electrochemically active components in the usual way.

[0059] Alternatively or additionally, the region containing the lithium reserve can be located in the core of the coil, these particular locations of the regions of the lithium reserve being particularly advantageous because these regions are not commonly used, and therefore it is particularly advantageous and economical to use these regions for the lithium reserve.

[0060] In another preferred further development, the lithium-ion cell of the invention is characterized in that it has at least one of the following characteristics a. to c.: a. The negative electrode formed as a composite electrode and the positive electrode formed as a composite electrode are part of a stack arranged one on top of the other. b. The negative and positive electrodes are separated from each other by a separator. a. An area formed as a lithium reserve is disposed at one end of the tape-shaped negative electrode and / or tape-shaped positive electrode.

[0061] It is particularly preferable that the immediately above features a to c are realized in combination with one another.

[0062] This configuration of negative and positive electrodes can also be used to advantage in different shapes of lithium ion cells, and this electrode configuration can be used to fabricate certain lithium ion cells having prismatic housings.

[0063] In one preferred further development, the lithium-ion cell of the invention is characterized in that it has at least one of the features a. or b. immediately below: a. an anode current collector and a cathode current collector each having two flat surfaces separated by a peripheral edge and each coated with an electrochemically active component on both surfaces; b. The area designated as the lithium reserve is located on only one flat surface of the anode current collector and / or the cathode current collector.

[0064] It is particularly preferred if the immediately above features a. and b. are realised in combination with one another.

[0065] In a particularly preferred configuration of the lithium-ion cell of the invention, both the anode current collector and the cathode current collector have two flat faces, which in each case are coated with the respective electrochemically active components, and the area containing the lithium reserve is preferably located on only one of the flat faces of the anode current collector and / or the cathode current collector.

[0066] In one preferred further development, the lithium-ion cell of the invention is characterized in that it has at least one of the features a. or b. immediately below: A lithium ion cell includes a housing that surrounds a negative electrode and a positive electrode. b. The area of ​​the negative or positive electrode that is formed as the lithium reserve faces the housing of the lithium ion cell.

[0067] It is particularly preferred if the immediately above features a. and b. are realised in combination with one another.

[0068] This configuration is particularly advantageous because these regions of the electrodes generally do not contribute to the electrochemical processes in lithium-ion cells and can therefore be used to particular advantage for lithium reserves. It is therefore in this embodiment in particular the end regions of the electrode arrangement that are used to introduce a coating of lithium-containing material instead of a coating of electrochemically active components.

[0069] In one very particularly preferred configuration, only the negative electrode is used to form the lithium reserve. In this embodiment, only the negative electrode has at least one region in which the anode current collector is at least partially free of electrochemically active components, this region being formed as the lithium reserve.

[0070] In one preferred further development, the lithium-ion cell of the invention is characterized in that it has at least one of the characteristics a. to h. immediately below: a. The lithium reserve comprises electrochemically active lithium disposed in a region above the anode current collector and / or the cathode current collector formed as a lithium reserve. b. The lithium reserve comprises activatable lithium disposed in a region above the anode current collector and / or the cathode current collector formed as a lithium reserve. c. The lithium reserve comprises at least one lithium-containing compound, particularly a lithium-containing alloy, that is disposed in a region above the anode current collector and / or the cathode current collector that is formed as a lithium reserve. d. The lithium reserve is formed from lithium foil placed in an area above the anode current collector and / or cathode current collector that is formed as a lithium reserve. e. A lithium reserve is formed from a lithium strip disposed in an area above the anode current collector and / or cathode current collector that is formed as a lithium reserve. f. The lithium reserve is formed from deposited lithium or lithium-containing material disposed in a region above the anode current collector and / or cathode current collector that is formed as a lithium reserve. g. The lithium reserve is formed from encapsulated lithium particles disposed in a region above the anode current collector and / or cathode current collector that is formed as a lithium reserve. h. A lithium reserve is formed from a coating disposed in a region above the anode current collector and / or cathode current collector that is formed as a lithium reserve.

[0071] Lithium or lithium-containing materials can be applied, for example in the form of a paste or another coating, onto the positive electrode and / or particularly the corresponding areas of the negative electrode. For example, encapsulated lithium particles such as SLMP (Stabilized Lithium Metal Powder, FMC Corporation, USA) can be used for this purpose.

[0072] The lithium in metallic form can be, for example, electrochemically deposited, vapor-deposited, or pressed.

[0073] The lithium reserve can be activated by cycles, which is particularly preferred.

[0074] The energy storage element of the present invention may be a button cell. Button cells are cylindrical and have a height smaller than their diameter. They are suitable for supplying electrical energy to small electronic devices such as wristwatches, hearing aids, and wireless headphones.

[0075] The energy storage element of the present invention is preferably a cylindrical button cell having a circular upper surface with at least a flat central region, a circular lower surface with at least a flat central region, and an annular casing disposed therebetween. The shortest distance between a point on the flat region or partial region of the upper surface and a point on the flat region or partial region of the lower surface is preferably within the range of 4 mm to 15 mm. The maximum distance between two points on the casing of the button cell is preferably within the range of 5 mm to 25 mm. Here, the maximum distance between two points on the casing surface is assumed to be greater than the distance between two points on the upper and bottom surfaces.

[0076] The nominal capacity of the energy storage element of the present invention formed as a button cell is generally at most 1500 mAh in one embodiment as a lithium ion cell. The nominal capacity is preferably within the range of 100 mAh to 1000 mAh, more preferably within the range of 100 to 800 mAh.

[0077] The energy storage element of the present invention may be a cylindrical round cell. Cylindrical round cells have a height greater than their diameter. They are suitable for supplying electrical energy to modern measurement applications, security applications, and automotive applications, such as electricity meters, water meters, and gas meters, heating cost meters, medical pipettes, sensors, and alarm devices, household alarm devices, sensors, and sensor networks, backup batteries for anti-theft systems in automotive engineering.

[0078] The height of the round cells is preferably in the range of 15 mm to 150 mm. The diameter of the cylindrical round cells is preferably in the range of 10 mm to 50 mm. Within these ranges, shape factors of, for example, 18×65 (diameter×height, in mm) or 21×70 (diameter×height, in mm) are particularly preferred. Cylindrical round cells with these shape factors are particularly suitable for powering electric drives in motor vehicles and tools.

[0079] The nominal capacity of the energy storage elements of the present invention formed as cylindrical round cells is typically up to 6000 mAh in one embodiment as a lithium ion cell. For a 21×70 form factor, the cells in one embodiment as a lithium ion cell preferably have a nominal capacity in the range of 2000 mAh to 5000 mAh, more preferably in the range of 3000 to 4500 mAh.

[0080] In the European Union, manufacturer information on the nominal capacity of secondary batteries is highly regulated. For example, information on the nominal capacity of secondary nickel-cadmium batteries is based on measurements according to the standards IEC / EN 61951-1 and IEC / EN 60622, information on the nominal capacity of secondary nickel-metal hydride batteries is based on measurements according to the standard IEC / EN 61951-2, information on the nominal capacity of lithium secondary batteries is based on measurements according to the standard IEC / EN 61960, and information on the nominal capacity of lead-acid secondary batteries is based on measurements according to the standard IEC / EN 61056-1. Any information on the nominal capacity in the present application is also preferably based on these standards. In one particularly preferred configuration, the lithium-ion cell of the present invention is configured such that the electrodes are formed in the shape of a coil according to what is known as a contact-plate design, in particular as described in WO 2017 / 215900 A1. WO 2017 / 215900A1 is incorporated herein by reference in its entirety.

[0081] In a particularly preferred embodiment, the lithium ion cell of the present invention comprises: In a composite unit of the electrodes and separators in the form of a coil, the positive and negative electrodes are offset from each other so that the longitudinal end of the anode current collector emerges from one end face and the longitudinal end of the cathode current collector emerges from the other end face; The lithium ion cell of the present invention has a metal contact plate disposed on one of the longitudinal ends, resulting in a linear contact zone; the contact plate is connected to the longitudinal ends along said linear contact zone by welding; It is characterized by:

[0082] When manufacturing composite units consisting of electrodes and separators, care should normally be taken to ensure that current collectors of opposite polarity do not protrude on the same side, as this may increase the risk of short circuits, but in the offset arrangement described, the current collectors of opposite polarity emerge from opposite end faces of the coil or stack, minimizing the risk of short circuits.

[0083] The projections of the current collectors resulting from the offset arrangement can be exploited by contacting them, preferably over their entire length, with corresponding current conductors. In this case, the aforementioned contact plates are used as current conductors. This allows a significant reduction in the internal resistance in the cell of the invention. The described arrangement can therefore adequately mitigate the generation of large currents. The minimal internal resistance also reduces heat losses at high currents. Furthermore, the dissipation of heat energy by the electrodes is also favored.

[0084] The contact plate can then be contacted to an electrode of a cell of the invention, for example an electrode in the housing.

[0085] There are several ways in which the contact plates can be connected to the longitudinal ends.

[0086] The contact plate can be connected to the longitudinal end along a linear contact zone by at least one weld line. The longitudinal end can, according to the invention, include one or more cross sections, each of which is continuously connected to the contact plate over its entire length by a weld line.

[0087] In one possible further development, the cross section which is continuously connected to the contact plate over its entire length can extend over at least 25%, preferably over at least 50%, more preferably over at least 75% of the total length of the longitudinal end.

[0088] Particularly preferably, the longitudinal ends can be welded continuously over their entire length to the contact plate.

[0089] In some preferred embodiments, the cells of the present invention have the following features: The contact plate is a metal plate having a thickness in the range of 200 μm to 1000 μm, preferably 400 to 500 μm. The contact plates are made of aluminum, titanium, nickel, stainless steel, or nickel-plated steel; The present invention has at least one of the following:

[0090] The contact plate may have at least one slot and / or at least one perforation, which serve to prevent deformation of the plate during the formation of the weld.

[0091] In a preferred embodiment, the contact plate is in the shape of a disk, in particular in the shape of a circular or at least approximately circular disk. It therefore has an externally circular or at least approximately circular disk edge. In this case, an approximately circular disk is to be understood as meaning in particular a disk having a circular shape with at least one separate arc, preferably 2 to 4 separate arcs.

[0092] Particularly preferably, the cell of the invention has a first contact plate on the longitudinal end of the anode current collector, thereby obtaining a first linear contact zone having a spiral shape, and a second contact plate on the longitudinal end of the cathode current collector, thereby obtaining a second linear contact zone having a spiral shape. Preferably, both contact plates are connected to the electrodes of the cell of the invention, for example to the electrodes in the housing.

[0093] In a particularly preferred embodiment, both the first contact plate and the anode current collector are made of the same material, which is particularly preferably selected from the group comprising copper, nickel, titanium, nickel-plated steel, and stainless steel.

[0094] The second contact plate and the cathode current collector are particularly preferably both made of the same material selected from the group comprising aluminium, titanium and stainless steel (for example type 1.4404).

[0095] The present invention further includes a coil or stack for a lithium-ion secondary electrochemical cell, the coil or stack having the following features: a. The coil or stack comprises at least one composite electrode as a negative electrode, which composite electrode comprises at least one anode current collector and at least one electrochemically active component capable of intercalating and deintercalating lithium ions. b. The coil or stack includes at least one composite electrode as a positive electrode, which composite electrode includes at least one cathode current collector and at least one electrochemically active component capable of intercalating and deintercalating lithium ions. c. the negative electrode and the positive electrode are separated from each other by a separator; d. The negative electrode and / or positive electrode have at least one region in which the anode current collector and / or cathode current collector are at least partially free of electrochemically active component, this region being formed as a lithium reserve.

[0096] With regard to further characteristics of this coil or this stack, in particular with regard to the formation of the lithium reserve, reference is made to the above descriptions.

[0097] Furthermore, the present invention includes a method for manufacturing a described coil or a described stack provided for a lithium-ion secondary electrochemical cell, the method comprising the steps of: a. providing a composite electrode as a negative electrode by coating at least one electrochemically active component capable of intercalating and deintercalating lithium ions on both sides of a tape-shaped and / or planar anode current collector; b. Coating at least one electrochemically active component capable of intercalating and deintercalating lithium ions on both sides of a tape-shaped and / or planar cathode current collector to provide a composite electrode as a positive electrode. c. During coating of the electrochemically active components on the anode current collector and / or the cathode current collector, excluding at least one area where the respective electrochemical component is not coated. d. adding a lithium-containing material to the at least one excluded region to form a lithium reserve. e. Processing the negative and positive electrodes together with at least one separator to form a coil or stack.

[0098] With regard to further features of this manufacturing method, in particular with regard to the electrodes and the lithium reserve region, reference is made to the above description.

[0099] Finally, the present invention includes a method for producing an electrochemical lithium ion cell in the manner described above, the method comprising the steps of: a. providing a coil or stack as described above. b. Placing the coil or stack in a housing. c. Supplying at least one electrolyte to the coil or stack. d. Making electrical contact between the negative and positive electrodes and the housing or with electrical conductors that can pass through the housing. e. Closing the housing.

[0100] The housing is in particular a housing that is conventional for such cells, for example a cylindrical round cell or a button cell. Furthermore, the method preferably includes electrical contact of the negative and positive electrodes. In some preferred embodiments, the electrical contact can be made by means of a separate electrical conductor. However, it is also possible to make a direct contact with the housing by means of the contact plate, in particular in the case of the contact plate design mentioned above.

[0101] Further features and advantages of the invention will become apparent from the following description of an embodiment in conjunction with the drawings, where each of the individual features can be realized independently of one another or in combination with one another. [Brief description of the drawings]

[0102] [Figure 1] FIG. 1 shows a schematic top view of an anode and cathode according to one preferred embodiment of the present invention. [Diagram 2] FIG. 2 shows a schematic cross-sectional view of the anode and cathode according to a preferred embodiment of the present invention shown in FIG. [Diagram 3] FIG. 1 shows a schematic diagram of an electrode arrangement arranged in a housing in the form of a coil (cross section) according to a preferred embodiment of the present invention. [Figure 4] FIG. 13 shows a top view of a current collector in a configuration with openings. [Diagram 5] FIG. 5 shows a cross-sectional view of the current collector shown in FIG. [Figure 6] FIG. 1 shows a top view of a negative electrode that can be fabricated into a lithium-ion cell of the present invention. [Figure 7] FIG. 7 shows a cross-sectional view of the negative electrode shown in FIG. [Figure 8] FIG. 7 shows a top view of a composite unit fabricated using a negative electrode, a positive electrode, and two separators. [Figure 9] FIG. 9 shows a cross-sectional view of a composite unit made of the electrode and separator shown in FIG. 8. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0103] Detailed Description of the Preferred Embodiments 1 and 2 show a negative electrode 10 and a positive electrode 20 in schematic top view (FIG. 1) and cross section (FIG. 2). In this example, the negative electrode 10, designed in the form of a tape, has at one end an area 11 designated as a lithium reserve. Both the negative electrode 10 and the positive electrode 20 are formed as composite electrodes, in which the anode current collector 12 in the case of the negative electrode 10 and the cathode current collector 22 in the case of the positive electrode 20 are coated on both sides with electrochemically active components 13 and 23, respectively. The electrochemically active component 13 of the negative electrode 10 may be, for example, a mixture of silicon and graphite and an electrode binder. The electrochemically active component 23 of the positive electrode 20 is, for example, a particulate lithium metal oxide compound in a binder matrix.

[0104] In the negative electrode 10, region 11 formed as a lithium reserve is disposed at one end of a tape electrode on one side of the anode current collector 12. The lithium-containing material present in region 11 may be, for example, a lithium foil or lithium strip. In another embodiment, it may take the form of evaporated lithium, or Hoest's lithium material, or other coating. For example, the lithium-containing material may be formed from encapsulated lithium particles that are applied onto the anode current collector 12 in the form of a coating.

[0105] The anode current collector 12 and the cathode current collector 22 can take the form of a conventional conductive foil, in particular a metal foil or foil tape. In the case of the negative electrode, copper or nickel is particularly suitable for this purpose. In the case of the positive electrode, aluminum is particularly suitable for this purpose. The anode current collector and the cathode current collector are preferably present in structured form, for example in perforated form or in the form of an open-cell foam.

[0106] FIG. 3 shows diagrammatically the structure of a coil 100 formed from electrodes 10 and 20. The coil 100 has a helical structure and is formed by winding a composite unit consisting of an anode 10 and a cathode 20 separated from each other by a separator 40 around the coil axis. For clarity, the electrodes 10 and 20 and the separator 40 are depicted spaced apart. In reality, they are placed directly on top of each other and connected to each other, for example by lamination. On the outside, the outer coil is formed by the anode 10, the outside of which partially comprises an area 11 formed as a lithium reserve. In this area, the anode 10 is not coated with electrochemically active components, but instead lithium material is added. The outer area of ​​the anode 10 does not face the cathode 20, but instead faces the inside of the housing 30.

[0107] Figures 4 and 5 illustrate the design of a perforated current collector 110 that can be used in the cells of the present invention. Figure 4 is a cross section along S1. The current collector 110 contains a number of openings 111, which are rectangular holes. Region 110a is characterized by openings 111, while in region 110b there are no openings along the longitudinal edge 110e. Thus, the current collector 110 has a much smaller weight per unit area in region 110a than in region 110b.

[0108] Figures 6 and 7 illustrate an anode 120 produced by applying an anode material 123 onto both sides of the current collector 110 shown in Figures 4 and 5. Figure 7 is a cross section along S2. Here, the current collector 110 has a tape-like main region 122 with a layer of anode material 123 and a free end strip 121 extending along the longitudinal edge 110e and free of electrode material 123. The electrode material 123 is further filled into the openings 111.

[0109] 8 and 9 illustrate an electrode-separator composite unit 104 manufactured using the negative electrode 120 shown in Figs. 6 and 7. In addition, it includes a positive electrode 130 and separators 118 and 119. Fig. 9 is a cross section along S3. The positive electrode 130 is constructed with the same current collector design as the negative electrode 120. The current collectors 110 and 115 of the negative electrode 120 and positive electrode 130 preferably differ only in their respective material choices. For example, the current collector 115 of the positive electrode 130 has a tape-like main area 116 with a layer of positive electrode material 125 and a free end strip 117 extending along a longitudinal end 115e and free of electrode material 125. By spiral winding, the composite unit 104 can be transformed into a coil so that it can be present in the cell of the invention.

Claims

1. 1. A lithium ion secondary electrochemical cell comprising: a. the lithium ion cell comprises at least one composite electrode as a negative electrode (10), the composite electrode comprising at least one anode current collector (12) and at least one electrochemically active component (13) capable of intercalating and deintercalating lithium ions; b. the lithium ion cell comprises at least one composite electrode as a positive electrode (20), the composite electrode comprising at least one cathode current collector (22) and at least one electrochemically active component (23) capable of intercalating and deintercalating lithium ions; It has the following characteristics: c) A lithium-ion secondary electrochemical cell, characterized in that said negative electrode (10) and / or said positive electrode (20) have at least one region (11) in which said anode current collector (12) and / or said cathode current collector (22) have at least one region (11) that is at least partially free of said electrochemically active component, said region (11) being formed as a lithium reserve.

2. a. the negative electrode (10) formed as a composite electrode and the positive electrode (20) formed as a composite electrode are each in the form of a tape; b. the negative electrode (10) and the positive electrode (20) are separated from each other by a separator (40); c. The negative electrode (10) and the positive electrode (20) are components of a coil (100); 10. The lithium ion electrochemical cell of claim 1 having the further feature:

3. a. The region (11) is disposed at a longitudinal end of the tape-shaped negative electrode (10) and / or the tape-shaped positive electrode (20); b. the region (11) containing the lithium reserve forms the outside of the coil (100) and / or defines a gap in the center of the coil (100); 3. The lithium ion electrochemical cell of claim 2 having the further features:

4. a. the negative electrode (10) formed as a composite electrode and the positive electrode (20) formed as a composite electrode are part of a stack arranged one on top of the other; b. the negative electrode (10) and the positive electrode (20) are separated from each other by a separator; c. The region (11) is located at the end of the tape-shaped negative electrode (10) and / or the tape-shaped positive electrode (20); 10. The lithium ion electrochemical cell of claim 1 having the further feature:

5. a. said anode current collector (12) and said cathode current collector (22) each have two flat faces separated by a peripheral edge and are coated on both faces with their respective electrochemically active components (13, 23); b. the area (11) formed as a lithium reserve is located only on one flat surface of the anode current collector (12) and / or the cathode current collector (22); A lithium-ion electrochemical cell according to any one of claims 1 to 4, further characterized in that:

6. a. the lithium ion cell comprises a housing (30) surrounding the negative electrode (10) and the positive electrode (20); b. the region (11) of the negative electrode (10) or the positive electrode (20) faces the housing (30) of the lithium-ion cell; A lithium-ion electrochemical cell according to any one of claims 1 to 5, further characterized in that:

7. a. only said negative electrode (10) has said at least one region (11) formed as a lithium reserve; The lithium ion electrochemical cell according to any one of claims 1 to 6, characterized in that

8. a. the lithium reserve comprises electrochemically active lithium disposed in the region (11) on the anode current collector (12) and / or the cathode current collector (22); b. the lithium reservoir comprises activatable lithium disposed in the region (11) on the anode current collector (12) and / or the cathode current collector (22); c. the lithium reserve comprises at least one lithium-containing compound, in particular a lithium-containing alloy, disposed in the region (11) on the anode current collector (12) and / or the cathode current collector (22); d. the lithium reserve is formed from a lithium foil placed in the region (11) on the anode current collector (12) and / or the cathode current collector (22); e. the lithium reserve is formed from a lithium strip disposed in the region (11) on the anode current collector (12) and / or the cathode current collector (22); f. the lithium reserve is formed from deposited lithium or lithium-containing material disposed in the region (11) on the anode current collector (12) and / or the cathode current collector (22); g. the lithium reserve is formed from encapsulated lithium particles disposed in the region (11) on the anode current collector (12) and / or the cathode current collector (22); h. the lithium reserve is formed from a coating disposed in the region (11) on the anode current collector (12) and / or the cathode current collector (22); A lithium-ion electrochemical cell according to any one of claims 1 to 7, having at least one of the following further features:

9. a. the lithium reserve is activatable by cycling; A lithium-ion electrochemical cell according to any one of claims 1 to 8, further characterized in that:

10. a. the lithium ion cell is a cylindrical round cell; b. the lithium ion cell is a button cell; A lithium-ion electrochemical cell according to any one of claims 1 to 9, characterized in that

11. a. the negative electrode (10) and the positive electrode (20) are components of the coil (100) according to claim 2 or claim 3, or the stack according to claim 4; b. the negative electrode (10) and the positive electrode (20) are offset in the coil (100) or stack such that a longitudinal end of the anode current collector (12) emerges from one end face of the coil or stack and a longitudinal end of the cathode current collector (22) emerges from the other end face of the coil or stack; c. the longitudinal end of the anode current collector (12) and / or the longitudinal end of the cathode current collector (22) contact a portion of the housing of the lithium-ion cell; A lithium-ion electrochemical cell according to any one of claims 1 to 10, further characterized in that:

12. 1. A coil (100) or stack for a lithium ion secondary electrochemical cell comprising: a. the coil (100) or stack comprises at least one composite electrode as the negative electrode (10), the composite electrode comprising at least one anode current collector and at least one electrochemically active component capable of intercalating and deintercalating lithium ions; b. said coil (100) or stack comprises at least one composite electrode as said positive electrode (20), said composite electrode comprising at least one cathode current collector and at least one electrochemically active component capable of intercalating and deintercalating lithium ions; c. The negative electrode (10) and the positive electrode (20) are separated from each other by a separator; It has the following characteristics: d) a coil (100) or stack, characterized in that said negative electrode (10) and / or said positive electrode have at least one region (11) and said anode current collector and / or said cathode current collector have at least one region (11) that is at least partially free of said electrochemically active component, this region (11) being formed as a lithium reserve.

13. The coil or stack according to claim 12, wherein the coil (100) or stack is further characterized by at least one feature according to any one of claims 2 to 11.

14. A method for manufacturing a coil (100) or a stack according to claim 12 or claim 13 for a lithium-ion secondary electrochemical cell, comprising the steps of: a. providing a composite electrode as a negative electrode (10) by coating at least one electrochemically active component (13) capable of intercalating and deintercalating lithium ions on both sides of a tape-like and / or planar anode current collector (12); b. Coating at least one electrochemically active component (23) capable of intercalating and deintercalating lithium ions on both sides of a tape-like and / or planar cathode current collector (22) to provide a composite electrode as a positive electrode (20); c. During the coating of the electrochemically active components on the anode current collector (12) and / or the cathode current collector (22), excluding at least one area (11) where the respective electrochemical component is not coated; d. adding a lithium-containing material to said at least one excluded region (11) to form a lithium reserve; e. processing the negative electrode (10) and the positive electrode (20) together with at least one separator to form a coil (100) or stack; A manufacturing method comprising:

15. A method for producing a lithium-ion electrochemical cell according to any one of claims 1 to 11, comprising the steps of: a. providing a coil (100) or stack manufacturable as claimed in claim 14; b. placing the coil (100) or stack in a housing (30); c. providing at least one electrolyte to said coil (100) or stack; d. bringing the negative electrode (10) and the positive electrode (20) into electrical contact with the housing (30) or with an electrical conductor capable of passing through the housing (30); e. closing the housing (30); A manufacturing method comprising:

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