Lithium-ion cells

Abstract

The secondary lithium-ion cell (100) comprises an electrode-separator assembly (104) with the sequence anode (120) / separator (118) / cathode (130). The anode (120) and cathode (130) are of strip-like design and each comprise a strip-like current collector (115, 125) with a first longitudinal end (115a, 125a) and a second longitudinal end, and are respectively loaded with electrode material (155, 123) in the strip-like main area (122, 116), and in each case the free end strips (121, 117) extending along the first longitudinal end (115a, 125a) are not loaded with electrode material. The electrode-separator assembly (104) is in the form of a coil with two terminal end faces and is surrounded by a housing. The anode (120) and cathode (130) are formed and / or positioned relative to one another within the electrode-separator assembly (104) such that the end strip (121) emerges from one of the terminal end faces and the end strip (117) emerges from the other of the terminal end faces. The cell includes a contact sheet metal member (113) in direct contact with one of the end strips (117, 121). The layer of negative electrode material (155) includes lithium titanate (LTO) and the layer of positive electrode material (123) includes lithium manganese oxide (LMO).

Description

[Technical field]

[0001] The invention described below relates to secondary lithium-ion cells. [Background technology]

[0002] Electrochemical cells can convert stored chemical energy into electrical energy by oxidation-reduction reactions. They usually include a positive electrode and a negative electrode separated from each other by a separator. During discharge, electrons are released at the negative electrode through an oxidation process. This results in an electronic current that can be extracted by an external electrical consumer, and thus the electrochemical cell acts as an energy supplier. At the same time, an ionic current corresponding to the electrode reactions is generated in the cell. This ionic current passes through the separator, which is made possible by an ion-conducting electrolyte.

[0003] If the discharge is reversible, i.e., the conversion of chemical energy to electrical energy during discharge can be reversed and the cell charged again, it is called a secondary cell. The common 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] Recently, secondary lithium-ion cells are used in many applications, since they are capable of obtaining high currents and are characterized by a relatively high energy density. They are based on the use of lithium, which in the form of ions can be transported back and forth between the electrodes of the cell. The negative and positive electrodes of lithium-ion cells are usually formed by so-called composite electrodes, which contain an electrochemically inactive component and an electrochemically active component.

[0005] In principle, any material capable of absorbing and releasing lithium ions can be used as the electrochemically active component (active material) of a secondary lithium-ion cell. Carbon-based particles such as graphitic carbon are often used in the negative electrode. Other non-graphitic carbon materials suitable for lithium intercalation can also be used, such as lithium titanate oxide (LTO). In addition, metallic and semi-metallic materials capable of alloying with lithium can also be used. For example, the elements tin, aluminum, antimony and silicon can form intermetallic phases with lithium. Lithium metal oxides such as lithium cobalt oxide (LiCoO2) and lithium manganate (LMO), lithium iron phosphate (LiFePO4) or their derivatives can be used as the active material of the positive electrode. The electrochemically active material is usually contained in the electrode in particulate form.

[0006] As electrochemically inactive components, composite electrodes generally contain flat and / or strip-shaped current collectors, e.g. metal foils, which serve as carriers for the respective active materials. 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 electrodes can contain electrode binders (e.g. polyvinylidene fluoride (PVDF) or other polymers, e.g. carboxymethyl cellulose), additives to improve conductivity, and other additives, as electrochemically inactive components. The electrode binder ensures the mechanical stability of the electrode and in many cases also the adhesion of the active materials to the current collectors.

[0007] The electrolyte used in lithium-ion cells is typically a solution of a lithium salt, such as lithium hexafluorophosphate (LiPF6), in an organic solvent (e.g., ethers and esters of carbonic acid).

[0008] During the manufacture of lithium-ion cells, the composite electrodes are combined with one or more separators to form an assembly. In this process, the electrodes and separators are connected to each other, usually under pressure, and sometimes by lamination or bonding. The basic functionality of the cell can then be obtained by impregnating the assembly with an electrolyte.

[0009] In many embodiments, the assembly is formed in the form of a coil or processed into a coil. Typically, this involves a positive electrode / separator / negative electrode sequence. The assembly is often produced as a so-called bi-cell, with possible sequences of negative electrode / separator / positive electrode / separator / negative electrode or positive electrode / separator / negative electrode / separator / positive electrode.

[0010] For applications in the automotive sector, or other applications with high energy requirements, such as e-bikes or tools, lithium-ion cells with the highest possible energy density are required that are also able to withstand high currents during charging and discharging.

[0011] Cells for the aforementioned applications are often designed as cylindrical round cells, for example with a form factor of 21×70 (diameter×height in mm). This type of cell always includes an assembly in the form of a winding. Modern lithium-ion cells of this form factor can already achieve energy densities up to 270 Wh / kg. However, this energy density is considered to be only an intermediate step. The market is already demanding cells with even higher energy densities.

[0012] However, when developing improved electrochemical cells, not only the energy density is taken into account, but also other factors. The internal resistance of the cell, which should be kept as low as possible to reduce power losses during charging and discharging, and the thermal connection of the electrodes, which can be important for regulating the temperature of the cell, are also very important parameters. These parameters are also very important in the case of cylindrical round cells, which include an assembly in the form of a coil. When the cell is charged quickly, heat accumulates in the cell due to power losses, which can lead to large thermomechanical stresses and subsequent deformation and damage of the cell structure. The risk is increased when the electrical connection of the current collectors is made by separate conductive arrester tabs welded to the current collectors, which emerge axially from the winding assembly, because heat generation can occur in these arrester tabs under heavy loads during charging and discharging. Such arrester tabs can be, for example, thin strips of metal foil several mm wide.

[0013] WO 2017 / 215900 A1 describes an electrode-separator assembly and a cell whose electrodes are in the form of ribbons and coils. Each electrode has a current collector loaded with electrode material. The electrodes of opposite polarity are arranged offset from each other in the electrode-separator assembly, so that the longitudinal end of the positive current collector emerges on one side of the coil and the longitudinal end of the negative current collector emerges from the other side of the coil. With regard to the electrical contact of the current collectors, the cell has at least one contact sheet metal member on one longitudinal end such that a linear contact zone is formed. The contact sheet metal member is connected to the longitudinal end along the linear contact zone by welding. This allows electrical contact to be made to the current collector and therefore to the associated electrode over its entire length. This significantly reduces the internal resistance in said cell. As a result, the generation of high currents can be very well mitigated. Summary of the Invention [Problem to be solved by the invention]

[0014] The invention was based on the problem of providing a lithium-ion cell which is characterized by an improved energy density compared to the prior art and at the same time has excellent properties in terms of its internal resistance and its capacity to passively dissipate heat. [Means for solving the problem]

[0015] This problem is solved by a lithium-ion cell having the features of claim 1. Preferred embodiments of the cell are given in the dependent claims.

[0016] The secondary lithium ion cell according to the present invention has the following characteristics a.-k: a. the cell includes an electrode-separator assembly having the sequence anode / separator / cathode; b. the anode is ribbon-shaped and includes a negative electrode material and a ribbon-shaped anode current collector having a first longitudinal end and a second longitudinal end; c. the anode current collector having a strip-shaped main area loaded with a layer of negative electrode material and a free end strip extending along a first longitudinal edge and not loaded with electrode material; d. the cathode is ribbon-shaped and includes a positive electrode material and a ribbon-shaped cathode current collector having a first longitudinal end and a second longitudinal end; e. the cathode current collector has a strip-shaped main area loaded with a layer of positive electrode material and a free end strip extending along a first longitudinal edge and not loaded with electrode material; f. the electrode-separator assembly is in the form of a coil having two ends; g. the electrode-separator assembly is enclosed within a housing; h. the anode and cathode are designed and / or positioned within the electrode-separator assembly such that a free end strip of the anode current collector emerges from one of the terminal end faces and a free end strip of the cathode current collector emerges from the other of the terminal end faces; i. the cell has a contact sheet metal member in direct contact with one of the end strips and connected directly to said end strip, preferably by welding or soldering; j. the layer of negative electrode material comprises lithium titanate oxide (LTO); and k. The layer of positive electrode material contains lithium manganese oxide (LMO). always have.

[0017] For clarity, the connection between the contact sheet metal member and the end strip of the anode or cathode current collector is direct: in the case of welding, the contact sheet metal member is fused directly to the free end strip, whereas in the case of soldering, at most a thin layer of solder metal is placed between the contact sheet metal member and the free end strip.

[0018] Direct connection of the contact sheet metal members to the electrode current collectors can ensure superior heat dissipation characteristics, as will be described below.

[0019] Furthermore, the free end strips extending along the first longitudinal ends include these longitudinal ends, and therefore the first longitudinal ends should be considered to be part of the respective end strips.

[0020] Electrochemical Systems The cell according to the invention is designed as a lithium-ion cell, i.e. it has electrodes capable of reversibly absorbing and releasing lithium. LTO in the negative electrode and LMO in the positive electrode are used for this purpose.

[0021] LMO is currently known as an electrode material for the positive electrodes of lithium-ion batteries. It has a spinel structure similar to that of the natural mineral MgAl2O4.

[0022] LTO is also known so far as an anode material for lithium-ion batteries, and is also available in a spinel structure.

[0023] A summary of suitable lithium manganese spinel compounds and suitable lithium titanate compounds is given below. - JBGoodenough / Journal of Power Sources 174(2007)996-1000 - Zaghib et al. / Materials 2013,6,1028-1049 - Lin et al. / Journal of Power Sources 248(2014)1034-1041 can be seen in.

[0024] One particular advantage is that the combination of electrode materials according to the invention (LTO / LMO) allows voltage compatibility with conventional supercapacitors. The cells according to the invention preferably have a nominal voltage in the range of 2.2-3.0 V, in particular 2.7 V, at room temperature. Cells with such a voltage window can replace supercapacitors in corresponding applications, but with a much higher capacity. The above combination of electrode materials in combination with the contact of the current collectors by contact sheet metal members endows the cells with a surprisingly good high current capacity, especially in the charging direction and also at low temperatures (<10° C.).

[0025] Preferred cathode side structure In a particularly preferred embodiment, the cathode of the cell according to the invention is characterized by at least one of the further features a. to d. immediately below: a. The positive electrode material contains LMO in a ratio of 70% by weight to 99.4% by weight. b. The positive electrode material includes an electrode binder and / or a conductive agent. c. The electrode binder is contained in the positive electrode material at a ratio of 0.5% by weight to 15% by weight. d. The conductive agent is contained in the positive electrode material at a ratio of 0.1% by weight to 15% by weight. Preferably, the immediately preceding additional features a. to d. are implemented in combination.

[0026] The percentages are based on the dry weight of the electrode material, i.e., the electrode material excluding electrolyte.

[0027] The active material of the cathode is preferably embedded in the matrix of the electrode binder, so that adjacent particles in the matrix are preferably in direct contact with each other. A conductive agent is used to increase the electrical conductivity of the electrode. Common electrode binders are based on, for example, polyvinylidene fluoride (PVDF), polyacrylate styrene-butadiene-rubber (SBR) or carboxymethyl cellulose. Common conductive agents are carbon black, graphite, graphene, carbon nanofibers and metal powders.

[0028] Preferably, the layer of positive electrode material on the cathode current collector has a thickness in the range of 20 μm to 300 μm.

[0029] Preferred anode side structure In a particularly preferred embodiment, the anode of the cell according to the invention is characterized by at least one of the further features a. to d. immediately below: a. The negative electrode material contains 70% to 99.4% by weight of LTO. b. The negative electrode material includes an electrode binder and / or a conductive agent. c. The electrode binder is contained in the negative electrode material at a ratio of 0.5% by weight to 15% by weight. d. The conductive agent is contained in the negative electrode material at a ratio of 0.1% by weight to 15% by weight. Preferably, the immediately preceding additional features a. to d. are implemented in combination.

[0030] The percentages here are also based on the dry weight of the electrode material, i.e., the electrode material excluding electrolyte.

[0031] The active material of the anode is preferably embedded in the matrix of the electrode binder, so that adjacent particles in the matrix are preferably in direct contact with each other. A conductive agent is used to increase the electrical conductivity of the electrode. Common electrode binders are based on, for example, polyvinylidene fluoride (PVDF), polyacrylate styrene-butadiene-rubber (SBR) or carboxymethyl cellulose. Common conductive agents are carbon black, graphite, graphene, carbon nanofibers and metal powders.

[0032] Preferably, the layer of negative electrode material on the anode current collector has a thickness in the range of 20 μm to 300 μm.

[0033] Separator The electrode-separator assembly preferably comprises at least one ribbon-shaped separator, and most preferably two ribbon-shaped separators, each of which has first and second longitudinal ends and two terminal ends.

[0034] The separator is preferably formed from an electrically insulating plastic film. It is preferred that the separator can be permeated by the liquid electrolyte. For this, for example, the plastic films used may have pores. These films may be made, for example, of polyolefins or polyetherketones. Nonwoven fabrics and cloths made of plastic materials or other electrically insulating cloths may also be used as separators. Separators with a thickness in the range of 5 μm to 50 μm are preferred.

[0035] The separator is impregnated with a liquid electrolyte for operation.

[0036] However, as an alternative to the separator-liquid electrolyte combination, the cell may also have, for example, a solid electrolyte.

[0037] The solid electrolyte is preferably a polymer solid electrolyte based on a polymer-conductive salt complex that exists in a single phase without any liquid component. The polymer solid electrolyte may have polyacrylic acid (PAA), polyethylene glycol (PEG) or polymethylmethacrylate (PMMA) as a polymer matrix. Lithium conductive salts such as lithium bis-(trifluoromethane)sulfonylimide (LiTFSI), lithium hexafluorophosphate (LiPF6) and lithium tetrafluoroborate (LiBF4) can be dissolved therein.

[0038] electrolyte In most cases, the cell preferably contains a liquid electrolyte, which consists of a solvent or solvent mixture and a lithium ion-containing conductive salt impregnated into the separator.

[0039] The cell preferably comprises an electrolyte which is a solvent or solvent mixture from the group comprising acetonitrile (ACN), propylene carbonate (PC), gamma-butyrolactone (GBL), adiponitrile (ADN), ethylene carbonate-diethyl carbonate (EC-DEC), ethylene carbonate-dimethyl carbonate (EC-DMC), ethylene carbonate-ethyl methyl carbonate (EC-EMC), ethylene carbonate-dimethyl carbonate-ethyl methyl carbonate (EC-DMC-EMC) and ethylene carbonate-dimethyl carbonate-diethyl carbonate (EC-DMC-DEC).

[0040] Additionally, the cell preferably includes an electrolyte containing a conductive salt selected from the group consisting of tetratethylammonium tetrafluoroborate (EtNBF), lithium hexafluorophosphate (LiPF), lithium hexafluoroarsenate (LiAsF), lithium tetrafluoroborate (LiBF), lithium perchlorate (LiClO), lithium bis(oxalato)borate (LiB(C0)), and LiP(CHO).

[0041] The conductive salt is preferably contained in the electrolyte at a ratio of 0.5M to 5M, particularly 2M.

[0042] In some preferred embodiments, the electrolyte includes an additive selected from the group consisting of vinylene carbonate (VC) and fluoroethylene carbonate (FEC).

[0043] In a first particularly preferred variant, the cell according to the invention is characterized by at least one of the following three further features a. to c. with regard to the electrolyte: a. The cell contains an electrolyte containing acetonitrile (ACN) as a solvent. b. The cell comprises an electrolyte comprising a conductive salt selected from the group consisting of tetraethylammonium tetrafluoroborate (EtNBF), lithium hexafluorophosphate (LiPF), lithium hexafluoroarsenate (LiAsF), lithium tetrafluoroborate (LiBF), lithium perchlorate (LiClO), lithium bis(oxalato)borate (LiB(CO)), and LiP(CHO), in particular lithium tetrafluoroborate (LiBF). c. The conductive salt is contained in the electrolyte at a concentration of 1.0 to 3.0 M, particularly 1.5 to 2.5 M. Particularly preferably, the immediately preceding three features a to c are realized in combination with one another.

[0044] In a second particularly preferred variant, the cell according to the invention is characterized by at least one of the following four further features a. to d. with respect to the electrolyte: a. The cell contains an electrolyte containing a mixture of propylene carbonate (PC) and gamma-butyrolactone (GBL) as a solvent. b. The volume ratio of PC to GBL in the mixture is in the range of 10:90 to 90:10, and it is particularly preferred that the volume ratio is 30:70. c. The cell contains an electrolyte comprising a conductive salt selected from the group consisting of tetraethylammonium tetrafluoroborate (Et4NBF4), lithium hexafluorophosphate (LiPF6), lithium hexafluoroarsenate (LiAsF6), lithium tetrafluoroborate (LiBF4), lithium perchlorate (LiClO4), lithium bis(oxalato)borate (LiB(C2O4)2), and LiP(C6H4O2)3. d. The conductive salt is contained in the electrolyte at a concentration of 0.5 to 5M, particularly 2M. The four immediately preceding features a. to d. are particularly preferably realized in combination with one another.

[0045] In a third particularly preferred variant, the cell according to the invention is characterized by at least one of the following three further features a. to c. with regard to the electrolyte: a. The cell contains an electrolyte that contains propylene carbonate (PC) as a solvent. b. The cell comprises an electrolyte comprising a conductive salt selected from the group consisting of tetraethylammonium tetrafluoroborate (Et4NBF4), lithium hexafluorophosphate (LiPF6), lithium hexafluoroarsenate (LiAsF6), lithium tetrafluoroborate (LiBF4), lithium perchlorate (LiClO4), lithium bis(oxalato)borate (LiB(C2O4)2), and LiP(C6H4O2)3, in particular lithium hexafluorophosphate (LiPF6). c. The conductive salt is contained in the electrolyte at a concentration of 1.0 to 2.0 M. The three immediately preceding features a. to c. are particularly preferably realized in combination with one another.

[0046] In a fourth particularly preferred variant, the cell according to the invention is characterized by at least one of the following five further features a. to e. with regard to the electrolyte: a. The cell contains an electrolyte that contains a mixture of ethylene carbonate (EC) and dimethyl carbonate (DMC) as a solvent. b. The volume ratio of EC to DMC in the mixture is in the range of 1:7 to 5:7, and particularly preferably the volume ratio is 3:7. c. The cell comprises an electrolyte comprising a conductive salt selected from the group consisting of tetraethylammonium tetrafluoroborate (Et4NBF4), lithium hexafluorophosphate (LiPF6), lithium hexafluoroarsenate (LiAsF6), lithium tetrafluoroborate (LiBF4), lithium perchlorate (LiClO4), lithium bis(oxalato)borate (LiB(C2O4)2), and LiP(C6H4O2)3, in particular lithium hexafluorophosphate (LiPF6). d. The conductive salt is contained in the electrolyte at a concentration of 1.0 to 2.0 M. e. The electrolyte contains vinylene carbonate (VC) as an additive, particularly at a concentration of 1% to 3% by weight. The immediately preceding five features a. to e. are particularly preferably realized in combination with one another.

[0047] In a fifth particularly preferred variant, the cell according to the invention is characterized by at least one of the six further features a. to f. immediately below with respect to the electrolyte: a. The cell contains an electrolyte containing a mixture of ethylene carbonate (EC), propylene carbonate (PC), and dimethyl carbonate (DMC) as a solvent. b. The ratio of the three components EC, PC and DMC to each other in the electrolyte is 1:2:7. c. The cell comprises an electrolyte comprising a conductive salt selected from the group consisting of tetraethylammonium tetrafluoroborate (Et4NBF4), lithium hexafluorophosphate (LiPF6), lithium hexafluoroarsenate (LiAsF6), lithium tetrafluoroborate (LiBF4), lithium perchlorate (LiClO4), lithium bis(oxalato)borate (LiB(C2O4)2), and LiP(C6H4O2)3, in particular lithium hexafluorophosphate (LiPF6). d. The conductive salt is contained in the electrolyte at a concentration of 0.5M to 5M. e. The cell contains an electrolyte including tetraethylammonium tetrafluoroborate (Et4NBF4) as a co-conducting salt. f. The conductive salt is contained in the electrolyte at a concentration of 0.1M to 2M. The six immediately preceding features a. to f. are particularly preferably realized in combination with one another.

[0048] The electrolyte according to the first variant has been found to be particularly advantageous. The solvent acetonitrile is often used in the capacitor area of ​​EDLCs. It is generally not used in lithium-ion cells, since it is not stable under normal electrochemical conditions. However, in the present case, no problems have arisen in this regard. Rather, it has been found that the cell according to the invention shows good cyclability with this electrolyte.

[0049] Particularly preferred embodiments of the separator The cell according to the invention is particularly preferably characterized by the following feature a: a. The separator includes at least one inorganic material that improves its resistance to thermal stress.

[0050] This material protects the separator from shrinkage caused by localized heating, which may occur in particular in the case of welding or soldering of contacting sheet metal members, thereby significantly reducing the risk of short circuits.

[0051] In a preferred further development, the cell according to the invention is characterized by at least one of the following features a. to c: The electrode-separator assembly includes a first separator and a second separator. b. The first separator and the second separator are identical. c. The electrode-separator assembly has the order anode / first separator / cathode / second separator or the order first separator / anode / second separator / cathode.

[0052] It is particularly preferred that the immediately preceding features a. and c., and optionally the immediately preceding features a. to c., are realized in combination with one another.

[0053] Preferably, both the first and second separators are improved against thermal stress with at least one inorganic material.

[0054] In a preferred further development, the cell according to the invention is characterized by the following feature a: a. At least one inorganic material is contained in the separator, particularly the first separator and / or the second separator, as a particulate filler material.

[0055] Thus, the separator may preferably be an electrically insulating plastic film in which particulate filling material is embedded. The plastic film preferably has, for example, micropores so that it can be permeated by the electrolyte. This film may be made, for example, of polyolefins or polyetherketones. It is not excluded that nonwovens and fabrics made of such plastic materials can also be used.

[0056] The proportion of particulate filler material in the separator is preferably at least 40% by weight, particularly preferably at least 60% by weight.

[0057] In a further preferred further development, the cell according to the invention is characterized by the following feature a: a. At least one inorganic material is present as a coating on a surface of the separator, particularly the first separator and / or the second separator.

[0058] Thus, the separator may preferably be a plastic film or a nonwoven or cloth or another electrically insulating sheet material onto which is coated a particulate filler material.

[0059] In this case, a separator having a base thickness in the range of 5 μm to 20 μm, preferably in the range of 7 μm to 12 μm, is preferably used. The above-mentioned preferred separator overall thickness is obtained by the base thickness and the coating thickness.

[0060] In some embodiments, only one side of a flat structure, particularly a plastic film, is coated with the inorganic material. In further embodiments, preferably both sides of a sheet structure, particularly a plastic film, are coated with the inorganic material.

[0061] The coating thickness is preferably in the range of 0.5 μm to 5 μm. This means that in the case of double-sided coating, the total thickness of the separator is preferably in the range of 6 μm to 30 μm, particularly preferably in the range of 8 μm to 22 μm. In the case of single-sided coating, the thickness is preferably in the range of 5.5 μm to 20.5 μm, particularly preferably in the range of 7.5 μm to 17 μm.

[0062] Where appropriate, the separator used may also preferably comprise an inorganic material as a filler, which may be the same or a different inorganic material as the coating.

[0063] In a further possible preferred embodiment, the cell according to the invention is characterized by at least one of the following features a. to e: a. The at least one inorganic material is or comprises an electrically insulating material. b. The at least one inorganic material is or includes at least one material selected from the group consisting of a ceramic material, a glass-ceramic material, and a glass. c. At least one inorganic material is or includes a lithium ion conducting ceramic material, such as Li5AlO4*Li4SiO4 or LiAlSi2O6. d. The at least one inorganic material is or includes an oxide material, particularly a metal oxide. e. The ceramic or oxide material is aluminum oxide (Al2O3), titanium oxide (TiO2), titanium nitride (TiN), titanium aluminum nitride (TiAlN), silicon oxide, in particular silicon dioxide (SiO2) or titanium carbonitride (TiCN).

[0064] It is particularly preferred that the immediately preceding features a. to c. or the immediately preceding features a., b., and d. or the immediately preceding features a., b., and e. are realized in combination with one another.

[0065] Of the aforementioned materials, aluminum oxide (Al2O3), titanium oxide (TiO2) and silicon dioxide (SiO2) are particularly preferred as coating materials.

[0066] In a further possible preferred embodiment, the cell according to the invention is characterized by at least one of the following features a. to c: a. The first separator and / or the second separator include at least one inorganic material only in specific regions. b. the first separator and / or the second separator have end strips along the first and / or second longitudinal edges and include at least one inorganic material therein as a coating and / or particulate filler material. c. The first separator and / or the second separator preferably have at least one band-shaped main region that is free of inorganic material. It is particularly preferable that the immediately preceding features a. to c. are realized in combination with one another.

[0067] It is by no means absolutely necessary that the separator contains a uniformly distributed inorganic material or is uniformly coated everywhere with said material. In fact, it may even be preferred that the separator is free of inorganic material in certain regions, such as the aforementioned main regions. In this region, the separator does not need to have as increased heat resistance as at the separator's ends. Moreover, inorganic material may cause an undesirable increase in the internal resistance of the cell according to the invention, especially in this region.

[0068] Preferred Construction of Electrode-Separator Assembly Formed as a Coil The strip-shaped anode, the strip-shaped cathode and the strip-shaped separator are preferably spirally wound into an electrode-separator assembly formed as a coil. Preferably, to produce the electrode-separator assembly, the strip-shaped electrodes are fed together with the strip-shaped separator to a winding device, where they are preferably spirally wound around a winding shaft. Alternatively, the electrodes and the separator can be combined to form an assembly and then wound. In some embodiments, the electrodes and the separator are wound onto a cylindrical or hollow cylindrical winding core for this purpose, which is placed on a winding mandrel and remains in the coil after winding. For example, the winding shell (shell of the coil) can be formed by a plastic film or an adhesive tape. The winding shell can also be formed from one or more separators wound up.

[0069] The longitudinal ends of the separator or separators preferably form end faces of an electrode-separator assembly formed as a coil.

[0070] It is also preferred that the end strips of the anode current collector and / or cathode current collector emerging from the end faces of the coil do not protrude more than 5000 μm from the end face, preferably not more than 3500 μm.

[0071] Particularly preferably, the end strips of the anode current collector do not protrude beyond the end face of the coil by more than 2500 μm, particularly preferably by more than 1500 μm, and particularly preferably, the end strips of the cathode current collector do not protrude beyond the end face of the coil by more than 3500 μm, particularly preferably by more than 2500 μm.

[0072] Within the electrode-separator assembly, the anode and cathode are preferably positioned offset from one another so that an end strip of the anode current collector emerges from one terminal end face of the electrode-separator assembly and an end strip of the cathode current collector emerges from the other terminal end face of the electrode-separator assembly.

[0073] Current collector It is particularly preferred that the energy storage element according to the invention comprises two metallic contact sheet metal members, in particular connected by welding or soldering, one of which is in direct contact with the free end strip of the anode current collector and the other of which is in direct contact with the free end strip of the cathode current collector.

[0074] The current collector of the cell according to the invention serves to electrically contact the electrochemically active components contained in the respective electrode materials over as large an area as possible.Preferably, the current collector is made of metal or is metallized at least on the surface.Suitable metals for the anode current collector include copper or nickel or another electrically conductive material, in particular an alloy of copper and nickel or a metal coated with nickel.Another option is stainless steel.Aluminum or another electrically conductive material, for example an aluminum alloy, is a suitable metal for the cathode current collector.Stainless steel, for example type 1.4404, is also an option in this case.

[0075] Preferably, each of the anode current collector and / or the cathode current collector is a metal foil having a thickness in the range of 4 μm to 30 μm, in particular a strip-shaped metal foil having a thickness in the range of 4 μm to 30 μm.

[0076] In a particularly preferred embodiment, the cell according to the invention is characterized by at least one of the features a. and b immediately below: a. The cathode current collector comprises or consists of aluminum or an aluminum alloy. b. The anode current collector comprises or is made of aluminum or an aluminum alloy. It is particularly preferred that the immediately preceding features a. and b. are realised in combination with each other.

[0077] In particular, the use of an aluminum current collector on the anode side, obtained by using LTO / LMO electrochemistry, has advantages over the use of, for example, copper-based current collectors. Aluminum is lighter than copper, and therefore the energy density of the cell can be significantly increased. Furthermore, cells according to the invention with aluminum foil as current collector and an anode based on LTO have been shown to be very stable towards deep discharge. The tendency to form dendrites appears to be significantly reduced.

[0078] The surface of the current collector, in particular one based on aluminum or an aluminum alloy, can preferably be coated with a carbon layer, in particular to reduce the contact resistance. This layer is preferably a few nm to a few μm thick and can be formed, for example, by deposition from the gas phase, for example a CVD process (CVD=chemical vapor deposition) or a spraying process.

[0079] In addition to films, metallic or metallized nonwoven fabrics or other strip-like structures such as open pore metal foams or expanded metal can also be used as current collectors.

[0080] The current collectors are preferably loaded on both sides with the respective electrode material, and therefore each of them preferably has a strip-like main area loaded on both sides with a layer of the respective electrode material.

[0081] When an alloy of aluminium, copper or nickel is mentioned in connection with the current collector, this preferably means an alloy in which the aluminium, copper or nickel content of the respective base metal is at least 70% by weight, preferably at least 90% by weight.

[0082] Low-material design for current collector In a particularly preferred embodiment, the cell according to the invention is characterized by at least one of the following features a. to c: a. A strip-shaped main area of ​​a current collector, which is connected to a contact sheet metal member, preferably by welding or soldering, has a number of openings. b. The openings in the main area are round or square holes, particularly punched or drilled holes. c. The current collectors, which are preferably connected to the contact sheet metal members by welding or soldering, are perforated in the main area, in particular by round or slot-shaped holes. Preferably, the immediately preceding features a. and b. or a. and c., particularly preferably the immediately preceding three features a. to c., are realised in combination with one another.

[0083] The large number of openings reduces the volume of the current collector, which in turn reduces its weight. This allows more active material to be introduced into the cell, thus significantly increasing the cell's energy density. This method can achieve energy density increases in the double-digit percentage range.

[0084] In some preferred embodiments, the openings are formed in the strip-shaped main region using a laser.

[0085] In principle, the shape of the openings is not important for the present invention. What is important is that by introducing the openings, the mass of the current collector is reduced and the openings can be filled with the active material, thus providing more space for the active material.

[0086] When inserting openings, it can be very advantageous to ensure that the maximum diameter of the openings is not too large. Preferably, the dimensions of the openings should not exceed twice the thickness of the layer of electrode material on the respective current collector.

[0087] In a particularly preferred embodiment, the cell according to the invention is characterized by the following feature a: a. The openings in the current collector, particularly in the main region, have diameters in the range of 1 μm to 3000 μm.

[0088] Within this preferred range, a diameter in the range of 10 μm to 2000 μm, preferably 10 μm to 1000 μm, and particularly preferably 50 μm to 250 μm, is more preferred.

[0089] Particularly preferably, the cell according to the invention is further characterized by at least one of the features a. and b immediately below: a. A current collector which is connected to a contact sheet metal member, preferably by welding or soldering, has a weight per unit area less than the free end strip of the same current collector, at least over a major area thereof. b. The current collectors, which are connected to the contact sheet metal members, preferably by welding or soldering, have no or fewer openings per unit area in the free end strips compared to within the main area. It is particularly preferred that the immediately preceding features a. and b. are realised in combination with each other.

[0090] The openings are preferably substantially uniformly distributed across the major area.

[0091] In a further particularly preferred embodiment, the cell according to the invention is characterized by at least one of the following features a. to c: a. The weight per unit area of ​​the current collector in the main area is 5% to 80% less than the weight per unit area of ​​the current collector in the free end strip. b. The current collector has a perforated area within the primary area in the range of 5% - 80%. c. Current collectors have a resistance of 20N / mm 2 ~250N / mm 2 It has a tensile strength of It is particularly preferable that the immediately preceding features a. to c. are realized in combination with one another.

[0092] The perforated area, often called 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.

[0093] The anode current collector and the cathode current collector preferably have the same or similar design with respect to the openings. The improvements in the achievable energy density in each case are additive. Thus, in a preferred embodiment, the cell according to the invention is further characterized by at least one of the features a. to c immediately below: a. Both the major strip-shaped area of ​​the anode current collector and the major area of ​​the cathode current collector are characterized by a number of openings as previously described. b. The cell includes a first contacting sheet metal member that is directly connected to one end strip, and a second contacting sheet metal member that is directly connected to the other end strip, particularly by welding or soldering.

[0094] It is particularly preferred that the immediately preceding features a. and b. are realised in combination with each other.

[0095] The preferred embodiments of the apertured current collectors described above can be applied independently to the anode and cathode current collectors.

[0096] The use of perforated or multiple-opening current collectors has not been considered of great importance for lithium-ion cells, since it is very difficult to electrically contact such current collectors. As mentioned at the beginning, the electrical connection of the current collectors is often made via separate arrester tabs. However, it is particularly difficult to make a reliable welded connection between these arrester tabs and perforated current collectors without introducing an unacceptable error rate in an industrial mass production process.

[0097] According to the invention, this problem is solved in particular by welding or soldering the aforementioned end strips to the contact sheet metal members. The concept according to the invention makes it possible to dispense with separate arrester lugs altogether and therefore allows the use of low-material current collectors provided with openings. In particular in the embodiment where the free end strips of the current collectors are not provided with openings, the welding or soldering can be performed reliably with a very low failure rate.

[0098] housing In a particularly preferred embodiment, the housing of the cell according to the invention is characterized by at least one of the features a. and b immediately below: The housing surrounding the electrode-separator assembly includes a metallic tubular housing portion having a circular opening at one end. b. The electrode / separator assembly, designed as a coil, is arranged axially within the housing, with the winding shell positioned against the inside of the tubular housing section. It is particularly preferred that the immediately preceding features a. and b. are realised in combination with each other.

[0099] Housing Closure Particularly preferably, the cell is characterized by the two features a. and b. immediately below: a. The contact sheet metal members have rounded ends. b. A contacting sheet metal member closes the distal circular opening of the tubular housing portion.

[0100] Therefore, according to the invention, it is proposed to use a contact sheet metal member with a circular end as the contact sheet metal member, which is used to close the end circular opening of the tubular housing part. Thus, now the contact sheet metal member is not only used to make electrical contact with the electrode, but also functions as a housing part. This is a great advantage, since a separate electrical connection between the contact sheet metal member and the housing part is no longer necessary. This creates space in the housing and simplifies the cell assembly. Furthermore, the direct connection of the housing part to the current collector of the cell provides excellent heat dissipation properties.

[0101] In a preferred further development, the cell according to the invention is characterized by at least one of the four features a. to d. immediately below: a. The contact sheet metal member is a metal disk or is part of a cover assembly that includes a metal disk. b. A metal disk is positioned within the tubular housing portion such that its ends are positioned against the inside of the tubular housing portion along a peripheral contact zone. c. The ends of the metal disc are connected to the tubular housing portion by a circumferential welded or soldered seam. d. One end strip is connected to a metal disk by welding or soldering. Particularly preferably, all of the four immediately preceding features a. to d. are realized in combination with one another.

[0102] In some embodiments, the metal disk is placed flat with the first longitudinal edge down, which in the case of a spirally wound electrode results in a linear contact zone having a spiral shape. In further embodiments, the first longitudinal edge, and therefore the edge strip, can be bent or deformed.

[0103] Since the end of the metal disc can be placed against the inside of the tubular housing part along the peripheral contact zone, the tubular housing part preferably has a circular cross section at least in the part where the end of the metal disc is placed, and this part is advantageously hollow cylindrical, the inside diameter of this part of the tubular housing part correspondingly adapting to the outside diameter of the end of the metal disc.

[0104] The welding of the ends of the metal disk to the tubular housing part can in particular be carried out using a laser, although it is also possible to fasten the metal disk by soldering or bonding.

[0105] A separate sealing element for the circumferential welded or soldered seam is not required. The metal disk and the tubular housing part are connected to each other in a sealed manner by the welded or soldered seam. Furthermore, the welded or soldered connection also ensures a substantially resistance-free electrical connection between the metal disk and the tubular housing part. In this case, the metal disk and the tubular housing part have the same polarity.

[0106] In a further preferred further development, the cell according to the invention is characterized by at least one of the four features a. to d. immediately below: a. The contact sheet metal member is a metal disk or is part of a cover assembly that includes a metal disk. b. The cell includes a ring-shaped seal made of an electrically insulating material that surrounds the circular end of the metal disk. c. The metal disc is positioned within the tubular housing portion such that a ring-type seal is positioned against the inside of the tubular housing portion along a peripheral contact zone. d. One end strip is connected to a metal disk by welding or soldering.

[0107] Particularly preferably, all of the four immediately preceding features a. to d. are realized in combination with one another. Thus, in this embodiment, it is proposed to use a contact sheet metal member having a circular end for fitting an annular seal made of an electrically insulating material to the circular end of the contact sheet metal member, and to use the contact sheet metal member to close the terminal circular opening of the tubular housing part. Alternatively, a cover assembly comprising a combination of a contact sheet metal member and a metal disk can be used instead of the contact sheet metal member. In this case, the seal is mounted over the end of the metal disk, and the terminal circular opening of the tubular housing part is closed with the cover assembly.

[0108] The cell may be closed, for example, by crimping or crimping where the seal is preferably compressed.

[0109] The annular seal can be arranged against the inside along the peripheral contact zone, so that in this case the tubular housing part also preferably has a circular cross section at least in the part where the seal is arranged, for which reason this part is advantageously hollow cylindrical, where the inner diameter of the tubular housing part corresponds to and matches the outer diameter of the end of the metal disc on which the seal is to be loaded.

[0110] The seal itself can be a standard plastic seal, which should be chemically resistant to the electrolyte used. Suitable sealing materials are known to those skilled in the art.

[0111] The sealing variant with a ring-type seal made of an electrically insulating material means that the contact sheet metal member is electrically insulated from the tubular housing part. This forms the electrode of the cell. In the sealing variant in which the ends of the metal disk are connected to the tubular housing part by a circumferential welded or soldered seam, the tubular housing part and the contact sheet metal member have the same polarity.

[0112] Metal disc design The contact sheet metal member may be part of the aforementioned cover assembly, which in addition to the contact sheet metal member includes the aforementioned metal disk and possibly other separate parts. In this case, the contact sheet metal member and the metal disk are preferably in direct contact with each other or in contact via an electrical conductor. In some further preferred embodiments, the contact sheet metal member is the aforementioned metal disk.

[0113] In the simplest embodiment, the metal disc is a flat sheet metal section with a circular perimeter that extends in only one plane. However, in many cases, more elaborate designs may be preferred. For example, the metal disc may be contoured, for example having one or more circular depressions and / or ridges, preferably in a concentric arrangement around its center, thereby forming, for example, a corrugated cross section. Its inside may also have one or more ridges or linear depressions and / or ridges. Furthermore, the disc may have ends that are bent radially inward, for example to have a double-layered end region with a U-shaped cross section, or be bent radially 90° to obtain an L-shaped cross section.

[0114] In a further development, the cell according to the invention is characterized by at least one of the three features a. to c. immediately below: A metal disc has at least one groove-type and / or dot-type depression on one side thereof which results in at least one linear and / or dot-type protuberance on the opposite side thereof. b. The side having the at least one ridge directly contacts the end strip. c. The at least one ridge and the end strip are connected via at least one weld or solder point and / or at least one weld or solder seam. The immediately preceding features a. to c. are particularly preferably realized in combination.

[0115] The end strip is therefore preferably welded or soldered directly to the at least one ridge.

[0116] In some embodiments, one end strip may be bent or deformed by contacting at least one ridge.

[0117] Furthermore, it may be preferred that the beads are introduced as elongated depressions. A preferred further development of the metal disk of the cell according to the invention is therefore characterized by at least one of the following two features a. and b: A metal disk has several groove-type depressions, e.g., a star-shaped arrangement, on one side thereof, which give rise to linear ridges on the other side. b. The metal disc includes at least one weld or solder seam, preferably two parallel weld seams, in each of the groove-shaped recesses as a result of welding or soldering the metal disc to the end strip. The immediately preceding features a. and b. are particularly preferably realised in combination.

[0118] The star-shaped arrangement and, if necessary, the double welded seam ensure a good and particularly uniform connection of the metal disk to one end strip.

[0119] Multi-Part Cover Assembly In a particularly preferred further development, the cell according to the invention is characterized by at least one of the following features a. and b: This includes a cover assembly which includes the aforementioned metal disk in addition to the contact sheet metal member. b. The contact sheet metal member directly contacts the end strip and is connected to the end strip by welding or soldering. The immediately preceding features a. and b. are particularly preferably realised in combination.

[0120] Thus, in this embodiment, the cover assembly includes at least two separate parts, where a metal disk is used to close the housing, while a contact sheet metal member contacts the end strips of the current collector.

[0121] In some preferred embodiments, the contacting sheet metal members may have a circular perimeter, although this is by no means required, in some cases, for example, the contacting sheet metal members may be metal strips or may have several strip-like segments, for example in a star-shaped arrangement.

[0122] In some embodiments, contact sheet metal members can be used that have at least one slot and / or at least one hole and / or at least one perforation, which can serve to limit deformation of the contact sheet metal members when forming a welded or soldered connection to the end strip.

[0123] Additionally, the contact sheet metal members may have indentations, such as holes or gaps, which are used to simplify the distribution of electrolyte during feeding and to facilitate the release of gases that occur during formation or as a result of abuse or defects from inside the coil.

[0124] Preferably, the contact sheet metal member and the metal disc are disposed flat on top of each other in at least some areas, thereby forming a two-dimensional contact surface.

[0125] Preferably, the contact sheet metal element and the metal disk are in direct contact with one another, in which case they are particularly preferably fastened to one another by welding or soldering.

[0126] In a particularly preferred embodiment, the contact sheet metal parts are designed like the contact sheet metal parts described in WO 2017 / 215900 A1.

[0127] In a particularly preferred embodiment, the cover assembly may include, in addition to the metal disk and possibly also in addition to the contact sheet metal member, a contoured metal electrode cover with a circular perimeter, which may be welded or soldered onto the metal disk and has approximately or exactly the same diameter as the metal disk, whereby the ends of the metal disk and the ends of the electrode cover together form the ends of the cover assembly. In a further embodiment, the ends of the electrode cover may be surrounded by the radially inwardly bent ends of the metal disk. In a preferred embodiment, there may be a clamp connection between the two separate parts.

[0128] Welding of contact elements to one end strip The concept of welding the ends of current collectors with contact elements is already known from WO 2017 / 215900 A1 or JP 2004-119330 A. This technique allows a particularly high current carrying capacity and a low internal resistance. Reference is therefore made to the entire contents of WO 2017 / 215900 A1 and JP 2004-119330 A with regard to the method of electrically connecting contact elements, in particular disk-shaped contact elements, to the ends of current collectors.

[0129] Variations of the housing with a housing cup As explained above, the housing of the cell according to the invention is characterized in one preferred embodiment by comprising a metallic tubular housing part having a circular opening at an end, a contacting sheet metal member having a circular end and closing the circular opening at the end of the tubular housing part, one end strip being connected to the contacting sheet metal member by welding or soldering.

[0130] In a particularly preferred further development, the cell according to the invention is characterized in relation to its housing by at least one of the following further features a. and b.: The tubular housing portion is part of a metal housing cup having a circular base. b. Another end strip is placed directly onto the floor and is connected to the floor, preferably by welding or soldering. The immediately preceding features a. and b. are particularly preferably realised in combination.

[0131] This variant is particularly suitable for cells according to the previously described closure variant having a ring-type seal made of electrically insulating material.

[0132] The use of housing cups in the construction of cell housings has long been known, for example from the first mentioned WO 2017 / 215900 A1, but the direct connection of the end strips of the current collector to the base of the housing cup, as proposed herein, is not known.

[0133] It is therefore possible, and according to the invention, and is preferred, to connect the end strips of the current collector emerging from the opposite end faces of the electrode-separator assembly formed as a coil directly to the aforementioned contact sheet metal members which serve as housing parts, i.e. as base and closure elements of the cup, so that the utilization of the available internal volume of the cell housing for the active components approaches its theoretical optimum.

[0134] Housing Material The choice of material from which the housing cup and contact sheet metal members are made is usually determined by whether they are in electrical contact with the anode or cathode current collector. The same material from which the current collector itself is made is generally preferred. The described components can be made, for example, from the following materials:

[0135] Alloyed or unalloyed aluminium, alloyed or unalloyed titanium, alloyed or unalloyed nickel, alloyed or unalloyed copper, stainless steel (e.g. type 1.4303 or 1.4404), nickel-plated steel.

[0136] Furthermore, the housing and its components may consist of multi-layer materials (clad materials), for example a layer of steel and a layer of aluminum or copper. In these cases, the aluminum layer or the copper layer forms, for example, the inside of the housing cup or the base of the housing cup.

[0137] Other suitable materials will be known to those skilled in the art.

[0138] When an alloy of aluminium, copper or nickel is mentioned in connection with the housing material, this preferably means an alloy in which the aluminium, copper or nickel content of the respective base metal is at least 70% by weight, preferably at least 90% by weight.

[0139] Preferred electrode design At the free end strips, the metal of each current collector is preferably free of the respective electrode material, hi some preferred embodiments, the metal of each current collector is uncoated and available for electrical contact, for example by the aforementioned welding or soldering to a contact sheet metal member.

[0140] However, in some further embodiments, at least some areas of the metal of each current collector in the free end strip may be coated with a support material that is more heat resistant than the current collector on which it is coated and that is different from the electrode material disposed on each current collector.

[0141] As used herein, "more thermally stable" means that the support material maintains its solid state at temperatures at which the metal of the current collector melts, and thus either has a higher melting point than the metal, or sublimes or decomposes at temperatures where the metal is already molten.

[0142] A support material that can be used in connection with the present invention can in principle be a metal or a metal alloy, provided that this or that has a higher melting point than the metal constituting the surface to be coated with the support material. In many embodiments, however, the cell according to the invention is preferably characterized by at least one of the further features a. to d immediately below: The support material is a non-metallic material. b. The support material is an electrically insulating material. c. The non-metallic material is a ceramic material, a glass-ceramic material, or a glass. d. The ceramic material is aluminum oxide (Al2O3), titanium dioxide (TiO2), titanium nitride (TiN), titanium aluminum nitride (TiAlN), silicon oxide, in particular silicon dioxide (SiO2) or titanium carbonitride (TiCN).

[0143] According to the invention, the support material is particularly preferably formed according to the immediately preceding characteristic b., particularly preferably according to the immediately preceding characteristic d.

[0144] The term non-metallic materials includes in particular plastic, glass and ceramic materials.

[0145] The term electrically insulating material is to be interpreted broadly here: in principle this includes all electrically insulating materials, in particular the aforementioned plastics.

[0146] The term ceramic material should be interpreted broadly here: in particular it includes carbides, nitrides, oxides, silicides or mixtures and derivatives of these compounds.

[0147] The term "glass-ceramic material" refers in particular to a material that includes crystalline particles embedded in an amorphous glass layer.

[0148] The term "glass" refers essentially to any inorganic glass that meets the thermal stability criteria defined above and that is chemically stable with respect to any electrolyte present in the cell.

[0149] The anode current collector is preferably made of copper or a copper alloy, while the cathode current collector is made of aluminum or an aluminum alloy, and the support material is aluminum oxide or titanium oxide.

[0150] It may be preferred that the free end strips of the anode and / or cathode current collectors are covered with a strip of support material.

[0151] The main areas, in particular the strip-shaped main areas, of the anode and cathode current collectors preferably extend parallel to the respective ends or longitudinal ends of the current collectors, preferably over at least 90%, particularly preferably over at least 95%, of the area of ​​the anode and cathode current collectors.

[0152] In some preferred embodiments, the support material is preferably attached in the form of strips or lines adjacent to the strip-like main areas, but does not completely cover the free areas, so that the metal of each current collector is directly exposed along the longitudinal edges.

[0153] Another preferred embodiment of the cell according to the invention The cells according to the invention may be button cells. Button cells are cylindrical in shape and have a height smaller than their diameter. Preferably, the height is in the range of 4 mm to 15 mm. It is also preferred that the button cells have a diameter in the range of 5 mm to 25 mm. Button cells are suitable for supplying electrical energy to small electronic devices such as, for example, watches, hearing aids and wireless headphones.

[0154] The nominal capacity of the button cell according to the invention, designed as a lithium-ion cell, is generally at most 1500 mAh, preferably in the range from 100 mAh to 1000 mAh, particularly preferably in the range from 100 to 800 mAh.

[0155] However, the cells according to the invention are particularly preferably cylindrically round cells, which have a height greater than their diameter. These are particularly suitable for the aforementioned applications with high energy requirements, for example in the automotive sector or e-bikes or power tools.

[0156] The height of cells designed as round cells is preferably in the range from 15 mm to 150 mm. The diameter of cylindrical round cells is preferably in the range from 10 mm to 60 mm. Within these ranges, form 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 form factors are particularly suitable for supplying electric power to electric drives of motor vehicles.

[0157] The nominal capacity of the cylindrical round cell according to the invention designed as a lithium-ion cell is preferably at most 90000 mAh. In a 21x70 form factor, the cell in one embodiment as a lithium-ion cell preferably has a nominal capacity in the range of 1500 mAh to 7000 mAh, particularly preferably in the range of 3000 to 5500 mAh. In a 18x65 form factor, the cell in one embodiment as a lithium-ion cell preferably has a nominal capacity in the range of 1000 mAh to 5000 mAh, particularly preferably in the range of 2000 to 4000 mAh.

[0158] 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 must be based on measurements in accordance with the IEC / EN 61951-1 and IEC / EN 60622 standards, information on the nominal capacity of secondary nickel-metal hydride batteries must be based on measurements in accordance with the EC / EN 61951-2 standard, information on the nominal capacity of secondary lithium batteries must be based on measurements in accordance with the IEC / EN 61960 standard, and information on the nominal capacity of secondary lead-acid batteries must be based on measurements in accordance with the IEC / EN 61056-1 standard. Any information on nominal capacity in the present application is preferably based on these standards.

[0159] In the embodiment in which the cell according to the invention is a cylindrical round cell, the anode current collector, the cathode current collector and the separator are preferably ribbon-shaped and preferably have the following dimensions: - Lengths ranging from 0.5m to 25m - Width in the range of 30mm~145mm has.

[0160] The free end strip extending along the first longitudinal edge and not loaded with electrode material preferably has a width of less than or equal to 5000 μm in these cases.

[0161] For cylindrical round cells of 18×65 form factor, the current collectors are preferably - a width between 56 mm and 62 mm, preferably 60 mm; and - Length not exceeding 2m, preferably not exceeding 1.5m has.

[0162] For a cylindrical round cell of 21×70 form factor, the current collector is preferably - a width of 56 mm to 68 mm, preferably 65 mm, and - Length not exceeding 3m, preferably not exceeding 2.5m has.

[0163] In one particularly preferred embodiment of the invention, the cell according to the invention is characterized by the following further features: a. The contacting sheet metal member or a cover assembly having a contacting sheet metal member includes a relief valve capable of relieving pressure from the housing if a further pressure threshold is exceeded.

[0164] This safety valve may for example be a rupture membrane, a rupture cloth or a similar predefined crack site which may burst at a defined overpressure in the cell to avoid the explosion of the cell For example, the metal disk of the cover assembly may have a safety valve, particularly in the form of a predefined crack site.

[0165] Square Design The present invention also includes an energy storage element that includes a stack of multiple anodes and multiple cathodes encased within a prismatic housing.

[0166] Therefore, in particular, the present invention also includes an energy storage element having the following characteristics a. to k.: a. it comprises a plurality of anodes and cathodes; b. each anode comprises an anode current collector and a negative electrode material; c. Each anode current collector is - a main area loaded with a layer of anode material; a free end strip extending along one end of the anode current collector and not loaded with negative electrode material; having d. each cathode includes a cathode current collector and a positive electrode material; e. Each cathode current collector is - a main area loaded with a layer of positive electrode material; a free end strip extending along one end of the cathode current collector and not loaded with positive electrode material; having f. the anodes and cathodes are stacked, whereby the anodes and cathodes in the stack are separated by a layer of separator or solid electrolyte; g. the stack is enclosed within a rectangular housing; h. a free end strip of the anode current collector protruding from one side of the stack and a free end strip of the cathode current collector protruding from another side of the stack; i. the energy storage element has a contact sheet metal member in direct contact with the free end strips of the anode current collector and / or the cathode current collector; j. the layer of negative electrode material comprises lithium titanate oxide (LTO); and k. The layer of cathode material comprises lithium manganese oxide (LMO).

[0167] As in the case of the lithium-ion cell according to the invention, the same preferred embodiments apply to the layer of anode material, the layer of cathode material, the current collectors and the separators, and if the energy storage element comprises an electrolyte, the same applies to the electrolyte. [Brief description of the drawings]

[0168] [Figure 1] FIG. 2 shows a top view of a current collector in one embodiment according to the present invention. [Diagram 2] 2 shows a cross-sectional view of the current collector shown in FIG. 1. [Diagram 3] FIG. 1 shows a top view of an anode that can be fabricated into an electrode-separator assembly in the form of a coil. [Figure 4] FIG. 4 is a cross-sectional view of the anode shown in FIG. [Diagram 5] FIG. 4 shows a top view of an electrode-separator assembly fabricated using the anode shown in FIG. 3. [Figure 6] FIG. 6 is a cross-sectional view of the electrode-separator assembly shown in FIG. 5. [Figure 7] 1A-1D show various embodiments of contact sheet metal members or cover assemblies of a cell according to the invention (cross-sectional views). [Figure 8] FIG. 2 is a partial cross-sectional view of one embodiment of a cell according to the present invention. [Figure 9] FIG. 2 is a partial view (cross-section) of a further embodiment of a cell according to the invention. [Figure 10] FIG. 2 is a diagram (cross-section) of a further embodiment of a cell according to the invention. [Figure 11] FIG. 2 is a diagram of a further embodiment of a cell according to the invention (cross-sectional view). [Figure 12] 1 is a graph of the results of three cycle tests. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0169] 1 and 2 show the design of the current collector 115. FIG. 2 is a cross-sectional view along S1. The current collector 115 includes a number of openings 211, which are rectangular holes. Region 115x features openings 211, while there are no openings in region 115z along the longitudinal edge 115a. Thus, the current collector 115 has a much smaller weight per unit area in region 115x than in region 115z.

[0170] Figures 3 and 4 show an anode 120 produced by attaching anode material 155 to both sides of the current collector 115 shown in Figures 1 and 2. Figure 4 is a cross section along S2. Here, the current collector 115 has a strip-shaped main area 122 loaded with a layer of anode material 123 and a free end strip 121 extending along the longitudinal edge 115a and not loaded with electrode material 155. Electrode material 155 also fills the openings 211.

[0171] Figures 5 and 6 show an electrode-separator assembly 104 manufactured using the anode 120 shown in Figures 3 and 4. It also includes a cathode 130 and separators 118 and 119. Figure 6 shows a cross-sectional view along S3. The cathode 130 is based on the same current collector design as the anode 120. Preferably, the current collectors 115 and 125 of the anode 120 and cathode 130 are both made of aluminum. The current collector 125 of the cathode 130 includes a strip-shaped main area 116 loaded with a layer of positive electrode material 123 and a free end strip 117 extending along a longitudinal end 125a and not loaded with electrode material 123. According to the invention, the electrode-separator assembly 104 is preferably in a spirally wound form and can be included in a cell according to the invention.

[0172] In some preferred embodiments, the free end strips 117 and 121 are coated in at least some areas on both sides with an electrically insulating support material, for example a ceramic material such as an oxide of silicon or aluminum.

[0173] 7 shows cross-sectional views of various embodiments AH of contact sheet metal members and cover assemblies suitable for closing the cell 100 according to the invention. In particular: A simplest embodiment of the contact sheet metal member 113 according to the invention is shown here, namely a flat metal disk with a circular periphery extending in only one plane. This metal disk can be made, for example, of aluminium. B The cover assembly 110 shown here includes a contact sheet metal member 113 in the form of a metal disk and a metal electrode cover 112. The contact sheet metal member 113 and the electrode cover 112 each have a circular circumference and the same diameter. The contact sheet metal member 113 extends in only one plane, while the electrode cover 112 is curved in the middle. The two components 112 and 113 of the cover assembly 110 are preferably connected to each other by welding or soldering (not shown). C The cover assembly 110 shown here comprises a contact sheet metal member 113 designed as a metal disk and a metal electrode cover 112. The electrode cover 112 is designed in the same way as the electrode cover of B. However, here the end 113a of the contact sheet metal member 113 is bent radially inwards, so that the contact sheet metal member 113 has a U-shaped cross section in the end region. The bent end 113a surrounds the end 112a of the electrode cover 112, whereby the electrode cover 112 is fixed on the contact sheet metal member 113. Regardless of this, the contact sheet metal member and the electrode cover 112 are preferably further welded or soldered to one another. The cover assembly 110 shown here includes a contact sheet metal member 113 in the form of a metal disk, and a metal disk 112. The contact sheet metal member 113 is disposed flat against, and preferably welded or soldered to, the metal disk 112. The metal disk 112 may be made, for example, of stainless steel, and the contact sheet metal member 113 may be made, for example, of an aluminum alloy. The contact sheet metal member 113 shown here is designed as a metal disk. In contrast to the metal disk shown in A, it has a circular depression 113b on its upper side and a corresponding ridge on its lower side, i.e. it is contoured. F. The contact sheet metal member 113 shown here comprises only a metal disk. Unlike the metal disk shown in A, it has edges 113a folded radially inward, thereby having a double layer edge region. The cover assembly 110 shown here comprises a contact sheet metal member 113 in the form of a metal disk and a metal electrode cover 112 curved in the middle. The end 113a of the contact sheet metal member 113 is bent radially inwards, so that the contact sheet metal member 113 has a U-shaped cross section in the end region. The bent end 113a surrounds the end 112a of the electrode cover 112, whereby the electrode cover 112 is fixed on the contact sheet metal member 113. Preferably, the ends s131a and 112a of the contact sheet metal member 113 and the electrode cover 112 are further connected to each other by a circumferential weld or solder seam (not shown). In the center of the contact sheet metal member 113 there is a hole 114 through which a cavity 116 is accessible, which is closed by the contact sheet metal member 113 and the electrode cover 112. An overpressure safety device 120 is integrated into the electrode cover 112, which can be activated if overpressure occurs within the cavity 116. In the simplest case, the overpressure protection 120 can be a predetermined crack site. The contact sheet metal member 113 shown here is designed as a metal disk. It has an end 113a bent at 90° and has an L-shaped cross section.

[0174] A closure element according to the invention which can be used as part of the variant of the housing having two lids described above can also preferably be designed according to the embodiments AH.

[0175] The cell 100 shown in Fig. 8 includes a cover assembly 110 shown in Fig. 7B, the end 110a of which is formed by the ends s113a and 112a of the contact sheet metal member 113 formed as a metal disk and the metal electrode cover 112. Together with the housing part 101, the cover assembly 110 forms the housing of the cell 100 and closes the end opening of the housing part 101. The end 110a of the cover assembly 110 is disposed along a peripheral contact zone on the inside 101b of the tubular housing part 101 and is connected to the tubular housing part 101 by a peripheral weld or solder seam. The end 101a of the housing part 101 is bent radially inward over the end 110a of the cover assembly 110.

[0176] The spirally wound electrode-separator assembly 104 is arranged axially within the housing so that its winding shell 104a is positioned against the inside of the tubular housing portion 101. An end strip 121 of anode current collector that is not covered with electrode material emerges from an upper end face 104b of the electrode-separator assembly 104 formed as a coil. It is welded or soldered directly to the underside of a contact sheet metal member 113.

[0177] The cell 100 shown in FIG. 9 includes a cover assembly similar to that shown in FIG. 1B, but different from each other. In the cover assembly 110 shown here, the metal disk 111, which is placed against the electrode cover 112, is not used for contacting the anode current collector. For this reason, it includes a metal contact sheet metal member 113, which has two sides, one of which, facing the metal disk 111, is placed further flat against it and is connected to the metal disk 111 by welding or soldering. The free end strip 121 of the anode current collector emerges from the upper end 104b of the electrode-separator assembly 104, which is formed as a coil. It is placed directly against the underside of the contact sheet metal member 113, to which it is welded or soldered.

[0178] The cell 100 shown in Figure 10 includes an electrode-separator assembly 104 that is axially inserted into a hollow cylindrical housing portion 101 so that its winding shell 104a is positioned against the inside 101b of the tubular housing portion 101. The electrode-separator assembly 104 includes a ribbon-shaped anode and a ribbon-shaped cathode that are spirally wound. The anode includes a ribbon-shaped anode current collector and a ribbon-shaped cathode current collector. The anode current collector is loaded with a layer of negative electrode material. The cathode current collector is loaded with a layer of positive electrode material.

[0179] A free end strip 121 of the anode current collector emerges from a top end 104b of the electrode-separator assembly 104 formed as a coil. A free end strip 117 of the cathode current collector emerges from a bottom end 104c of the electrode-separator assembly 104 formed as a coil.

[0180] The cell 100 comprises a tubular and hollow cylindrical metal housing part 101, which has two end openings. The upper opening is closed by a metal disk 111 arranged within the tubular housing part 101, with its end 111a positioned against the inside 101b of the tubular housing part 101 along a peripheral contact zone. The end 111a of the metal disk 111 is connected to the tubular housing part 101 by a peripheral welded or soldered seam.

[0181] The metal disk 111 is part of a cover assembly 110 which, in addition to the metal disk 111, includes a contact sheet metal member 113 and an electrode pin 108. The contact sheet metal member 113 has two sides, one of which is at the top of the figure and faces towards the metal disk 111. A longitudinal end 115a is placed directly against the other side of the contact sheet metal member 113, in this case the bottom side. The longitudinal end 115a is connected to the contact sheet metal member 113 by welding or soldering. The electrode pin 108 is welded or soldered to the contact sheet metal member 113 and exits the housing of the cell 100 through a central opening in the metal disk 111.

[0182] The cover assembly 110 further includes insulating means 103 to electrically insulate the electrode pins 108 and contact sheet metal members 113 , which are welded or soldered to the electrode pins relative to the metal disk 111 .

[0183] The bottom opening of the housing part 101 is closed with a closure element 145. The closure element 145 is a metal disk, the end 145a of which is placed against the inside 101b of the tubular housing part 101 along a peripheral contact zone. The end 145a of the closure element 145 is connected to the tubular housing part 101 by a welded or soldered seam.

[0184] The longitudinal end 125a of the cathode current collector is placed directly against the inner (upper) side of the contact sheet metal member 113. The longitudinal end 125a is connected to the closure element 145 by welding or soldering. The welding can be done, for example, by a laser through a metal disk of the closure element 145.

[0185] The cell 100 shown in FIG. 11 comprises a hollow cylindrical housing part 101 which is part of a housing cup 107 which comprises a circular base 107a and a circular opening (defined by a rim 101a). The housing cup 107 is a deep drawn part. Together with a lid assembly 110 which comprises a flat metal disk 111 with a circular rim 111a, the housing cup 107 surrounds an inside 137 on which an electrode-separator assembly 104 formed as a coil is axially arranged. The metal disk 111 is placed in the tubular housing part 101 and its end 111a is placed against the inside 101b of the tubular housing part 101 along a peripheral contact zone. Its end 111a corresponds to the end of the cover assembly and is connected to the tubular housing part 101 by a peripheral weld or solder seam. The end 101a of the tubular housing part 101 is bent radially inwards (here at about 90°) over the end 111a of the metal disk 111.

[0186] The electrode-separator assembly 104 is in the form of a cylindrical coil having two end faces between which extends a surrounding winding shell, which is placed against the inside of the hollow cylindrical housing part 101. It consists of positive and negative electrodes and separators 118 and 119, each formed as a strip and wound in a spiral. The two end faces of the electrode-separator assembly 104 are formed by the longitudinal ends of the separators 118 and 119. Current collectors 115 and 125, both made of aluminium, protrude from these end faces. The corresponding protrusions are indicated as d1 and d2.

[0187] The anode current collector 115 emerges from the upper end face of the electrode-separator assembly 104, and the cathode current collector 125 emerges from the lower end face. In the strip-shaped main area of ​​the anode current collector 115, a layer of negative electrode material 155 is loaded. In the strip-shaped main area of ​​the cathode current collector 125, a layer of positive electrode material 123 is loaded. The anode current collector 115 has an end strip 117 extending along its longitudinal end 115a and not loaded with electrode material 155. Instead, in this case, a coating 165 of ceramic support material is provided, which stabilizes the current collector in this area. The cathode current collector 125 has an end strip 121 extending along its longitudinal end 125a and not loaded with electrode material 123. Instead, in this case, a coating 165 of ceramic support material is provided.

[0188] In addition to the metal disk 111, the cover assembly 110 also includes a contact sheet metal member 113 and an electrode pin 108. The metal contact sheet metal member 113 includes two sides, one of which is at the top in the figure and faces towards the metal disk 111. On the other side of the contact sheet metal member 113, here at the bottom, the longitudinal end 115a directly contacts the contact sheet metal member 113 and thus the cover assembly 110 over its entire length and is connected to the latter by welding or soldering at least in some parts, preferably over its entire length. Alternatively, the aforementioned multi-pin connection may be present in this case. The cover assembly 110 thus functions simultaneously as an electrical contact for the anode and as a housing part.

[0189] The electrode pin 108 is welded or soldered to a contact sheet metal member 113 and exits the housing of the cell 100 through a central opening in a metal disk 111. The cover assembly 110 also includes insulating means 103, which electrically insulates the electrode pin 108 and thus the contact sheet metal member 113 from the metal disk 111 to which it is welded or soldered. Only the metal disk 111 is in direct contact, and therefore in electrical contact, with the housing cup 107. The electrode pin 108 and the sheet metal member 113 are insulated from the housing cup.

[0190] The end 125a of the cathode current collector 125 is in direct contact with the base 107a over its entire length and is connected to the latter at least in some parts, but preferably over its entire length, by welding (especially with a laser) or by soldering. Alternatively, the multi-pin connection mentioned above can also be used in this case. The base 107a thus serves not only as part of the housing but also as an electrical contact for the cathode.

[0191] The electrode-separator assembly 104 may, for example, comprise a positive electrode comprising 95% by weight LMO, 2% by weight electrode binder, and 3% by weight carbon black as a conductive agent. The anode 101 may, for example, comprise a negative electrode comprising 95% by weight LTO, 2% by weight electrode binder, and 3% by weight carbon black as a conductive agent. A 2M solution of lithium tetrafluoroborate (LiBF4) in acetonitrile may be used as the electrolyte.

[0192] The diagram shown in Figure 12 shows the good cyclability of the cell according to the present invention. At a load of 10C (charge) / 10C (discharge), nearly 80% of the initial capacity was achieved even after 5000 cycles. At loads of 3C / 1C and 5C / 5C, 1000 and 2500 cycles were also stably achieved.

Claims

1. A secondary lithium-ion cell, characterized in that a. the cell includes an electrode-separator assembly (104) having the following order: anode (120) / separator (118) / cathode (130); b. the anode (120) is ribbon-shaped and includes a negative electrode material (155) and a ribbon-shaped anode current collector (115) having a first longitudinal end (115a) and a second longitudinal end; c) the anode current collector (115) has a strip-shaped main area (122) on which a layer of the negative electrode material (155) is loaded, and a free end strip (121) extending along the first longitudinal end (115a) and not loaded with the negative electrode material (155); d. the cathode (130) is ribbon-shaped and includes a positive electrode material (123) and a ribbon-shaped cathode current collector (125) having a first longitudinal end (125a) and a second longitudinal end; e. the cathode current collector (125) has a strip-shaped main region (116) on which a layer of the positive electrode material (123) is loaded, and a free end strip (117) extending along the first longitudinal end (125a) and not loaded with the positive electrode material (123); f. The electrode-separator assembly (104) is in the form of a coil having two terminal end faces (104b, 104c); g. the electrode-separator assembly (104) is enclosed within a housing; h. the anode (120) and the cathode (130) are formed and / or positioned relative to one another within the electrode-separator assembly (104) such that the free end strip (121) of the anode current collector (115) emerges from one of the terminal end faces and the free end strip (117) of the cathode current collector (125) emerges from the other of the terminal end faces; i. said cell having a contact sheet metal member (113) in direct contact with one of said end strips (117, 121); j. the layer of anode material (155) comprises lithium titanate (LTO); k. The layer of positive electrode material (123) comprises lithium manganese oxide (LMO). A secondary lithium-ion cell having

2. Further features include: a. the cathode current collector (125) comprises or is made of aluminum or an aluminum alloy; b. The anode current collector (115) comprises or is made of aluminum or an aluminum alloy.

10. The cell of claim 1, wherein:

3. Further features include: a. The positive electrode material (123) contains the LMO in a ratio of 70% to 99.4% by weight; b. The positive electrode material (123) comprises an electrode binder and / or a conductive agent; c) The electrode binder is contained in the positive electrode material (123) at a ratio of 0.5% by weight to 15% by weight; d. The conductive agent is contained in the positive electrode material (123) at a ratio of 0.1% by weight to 15% by weight. The cell of claim 1 having at least one of:

4. Further features include: a. The layer of the positive electrode material (123) on the cathode current collector (125) has a thickness in the range of 20 to 300 μm.

10. The cell of claim 1, wherein:

5. Further features include: a. The negative electrode material (155) contains the LTO in a ratio of 70% to 99.4% by weight; b the negative electrode material (155) comprises an electrode binder and / or a conductive agent; c) The electrode binder is contained in the negative electrode material (155) at a ratio of 0.5% by weight to 15% by weight; d. The conductive agent is contained in the negative electrode material (155) at a ratio of 0.1% by weight to 15% by weight. The cell of claim 1 having at least one of:

6. Further features include: a. The layer of negative electrode material (155) on the anode current collector (115) has a thickness in the range of 20 μm to 300 μm.

10. The cell of claim 1, wherein:

7. Further features include: a) the cell contains an electrolyte which is a solvent or solvent mixture from the group consisting of acetonitrile (ACN), propylene carbonate (PC), gamma-butyrolactone (GBL), adiponitrile (ADN), ethylene carbonate-diethyl carbonate (EC-DEC), ethylene carbonate-dimethyl carbonate (EC-DMC), ethylene carbonate-ethyl methyl carbonate (EC-EMC), ethylene carbonate-dimethyl carbonate-ethyl methyl carbonate (EC-DMC-EMC), and ethylene carbonate-dimethyl carbonate-diethyl carbonate (EC-DMC-DEC); b. The cell contains tetraethylammonium tetrafluoroborate (Et ４ NBF ４ ), lithium hexafluorophosphate (LiPF ６ ), lithium hexafluoroarsenate (LiAsF ６ ), lithium tetrafluoroborate (LiBF ４ ), lithium perchlorate (LiClO ４ ), lithium bis(oxalato)borate (LiB(C ２ O ４ ) ２ ) and LiP(C ６ H ４ O ２ ) ３ an electrolyte containing a conductive salt selected from the group consisting of: c. The conductive salt is contained in the electrolyte at a ratio of 0.5M to 5M; d. the cell comprises an electrolyte comprising an additive selected from the group consisting of vinylene carbonate (VC) and fluoroethylene carbonate (FEC); The cell of claim 1 having at least one of:

8. Further features include: a. the cell contains an electrolyte containing acetonitrile (ACN) as a solvent; b. The cell contains tetraethylammonium tetrafluoroborate (Et ４ NBF ４ ), lithium hexafluorophosphate (LiPF ６ ), lithium hexafluoroarsenate (LiAsF ６ ), lithium tetrafluoroborate (LiBF ４ ), lithium perchlorate (LiClO ４ ), lithium bis(oxalato)borate (LiB(C ２ O ４ ) ２ ) and LiP(C ６ H ４ O ２ )3) the electrolyte is a conductive salt selected from the group consisting of: c. The conductive salt is contained in the electrolyte at a concentration of 1.0 to 3.0 M. The cell according to any one of claims 1 to 7, having

9. Further features include: a. the cell contains an electrolyte containing a mixture of propylene carbonate (PC) and gamma-butyrolactone (GBL) as a solvent; b. the volume ratio of PC:GBL in the mixture is in the range of 10:90 to 90:10; c. The cell contains tetraethylammonium tetrafluoroborate (Et ４ NBF ４ ), lithium hexafluorophosphate (LiPF ６ ), lithium hexafluoroarsenate (LiAsF ６ ), lithium tetrafluoroborate (LiBF ４ ), lithium perchlorate (LiClO ４ ), lithium bis(oxalato)borate (LiB(C ２ O ４ ) ２ ) and LiP(C ６ H ４ O ２ ) ３ comprising an electrolyte which is a conductive salt selected from the group consisting of: d. The conductive salt is contained in the electrolyte at a concentration of 0.5M to 5M. The cell according to any one of claims 1 to 7, having

10. Further features include: a. the cell contains an electrolyte containing propylene carbonate (PC) as a solvent; b. The cell contains tetraethylammonium tetrafluoroborate (Et ４ NBF ４ ), lithium hexafluorophosphate (LiPF ６ ), lithium hexafluoroarsenate (LiAsF ６ ), lithium tetrafluoroborate (LiBF ４ ), lithium perchlorate (LiClO ４ ), lithium bis(oxalato)borate (LiB(C ２ O ４ ) ２ ) and LiP(C ６ H ４ O ２ )3) the electrolyte is a conductive salt selected from the group consisting of: c. The conductive salt is contained in the electrolyte at a concentration of 1.0 to 2.0 M. The cell according to any one of claims 1 to 7, having

11. Further features include: a. the cell contains an electrolyte containing a mixture of ethylene carbonate (EC) and dimethyl carbonate (DMC) as a solvent; b. the volume ratio of EC:DMC in the mixture is in the range of 1:7 to 5:7; c. The cell contains tetraethylammonium tetrafluoroborate (Et ４ NBF ４ ), lithium hexafluorophosphate (LiPF ６ ), lithium hexafluoroarsenate (LiAsF ６ ), lithium tetrafluoroborate (LiBF ４ ), lithium perchlorate (LiClO ４ ), lithium bis(oxalato)borate (LiB(C ２ O ４ ) ２ ) and LiP(C ６ H ４ O ２ )3) the electrolyte is a conductive salt selected from the group consisting of: d. The conductive salt is contained in the electrolyte at a concentration of 1.0 to 2.0 M; e. The electrolyte contains vinylene carbonate (VC) as an additive. The cell according to any one of claims 1 to 7, having

12. Further features include: a. the cell contains an electrolyte containing a mixture of ethylene carbonate (EC), propylene carbonate (PC), and dimethyl carbonate (DMC) as a solvent; b. The ratio of the three components EC, PC and DMC in the electrolyte relative to each other is 1:2:7; c. The cell contains tetraethylammonium tetrafluoroborate (Et ４ NBF ４ ), lithium hexafluorophosphate (LiPF ６ ), lithium hexafluoroarsenate (LiAsF ６ ), lithium tetrafluoroborate (LiBF ４ ), lithium perchlorate (LiClO ４ ), lithium bis(oxalato)borate (LiB(C ２ O ４ ) ２ ) and LiP(C ６ H ４ O ２ )3) the electrolyte is a conductive salt selected from the group consisting of: d. The conductive salt is contained in the electrolyte at a concentration of 0.5M to 5M; e. The cell contains tetraethylammonium tetrafluoroborate (Et ４ NBF ４ ) as a co-conducting salt; f) The conductive salt is contained in the electrolyte at a concentration of 0.1M to 2M. The cell according to any one of claims 1 to 7, having

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