Rechargeable battery unit

Abstract

The present invention relates to a rechargeable battery cell (2, 20, 40) comprising an active metal, at least one positive electrode (4, 23, 44), at least one negative electrode (5, 22, 45), said negative electrode (5, 22, 45) containing an active material, a housing (1, 28) and an electrolyte, the invention relates to an electrolyte comprising an active material selected from the group consisting of an intercalation material made of carbon, an alloying active material, an intercalation material free of carbon, and a conversion active material, and the electrolyte is based on SO2 and contains at least one first conductive salt of formula (I), m is a metal selected from the group consisting of alkali metals, alkaline earth metals, Group 12 metals of the Periodic Table of Elements, and aluminum; x is an integer from 1 to 3; the substituents R1, R2, R3 and R4 are independently selected from the group consisting of a C1-C10 alkyl group, a C2-C10 alkenyl group, a C2-C10 alkynyl group, a C3-C10 cycloalkyl group, a C6-C14 aryl group and a C5-C14 heteroaryl group; and Z is aluminum or boron.

Description

[0001] This application is a divisional application of the following application: application date July 30, 2020, application number 202080007173.X, invention title "Rechargeable battery cell". Technical Field

[0002] The present invention relates to a rechargeable battery cell having a SO2-based electrolyte. Background Art

[0003] Rechargeable battery cells are very important in many technical fields. They are typically used for small rechargeable batteries that only require a relatively low current intensity, for example, for the operation of mobile phones. In addition, there is a great need for rechargeable battery cells for high-energy applications, and it is particularly important to store energy in large quantities in the form of battery cells for vehicle electric propulsion.

[0004] High energy density is an important requirement for these types of rechargeable battery cells. This means that the rechargeable battery cell per unit weight and volume should contain as much electrical energy as possible. As an active metal, lithium has proven to be particularly advantageous for this purpose. The active metal of a rechargeable battery cell refers to the metal whose ions migrate to the negative electrode or the positive electrode in the electrolyte and participate in the electrochemical process there when the battery is being charged or discharged. These electrochemical processes directly or indirectly result in the release of electrons to the external circuit or the absorption of electrons from the external circuit. A rechargeable battery cell including lithium as the active metal is also referred to as a lithium-ion battery. The energy density of these lithium-ion batteries can be increased by increasing the specific capacity of the electrodes or by increasing the battery voltage.

[0005] Both the positive electrode and the negative electrode of a lithium-ion battery are designed as insertion electrodes. In the understanding of the present invention, the term "insertion electrode" refers to an electrode having a crystal structure in which ions of the active material can be stored or removed from the crystal structure during the operation of a lithium-ion battery. This means that the electrode process can occur not only on the electrode surface but also within the crystal structure. When charging a lithium-ion battery, the active metal ions are removed from the positive electrode and stored in the negative electrode. When discharging a lithium-ion battery, the reverse process occurs.

[0006] The electrolyte is also an important functional component of each rechargeable battery cell. It typically comprises a solvent or solvent mixture and at least one conductive salt. For example, a solid electrolyte or an ionic liquid does not contain a solvent, but only a conductive salt. The electrolyte is in contact with the positive and negative electrodes of the battery cell. At least one type of ion (anion or cation) in the conductive salt moves sufficiently in the electrolyte so that charge transport required for the rechargeable battery function can be carried out between the electrodes by ionic conduction. The electrolyte is electrochemically decomposed by oxidation at a certain higher voltage of the rechargeable battery cell. This process usually results in irreversible damage to the electrolyte components, thus leading to the failure of the rechargeable battery cell. When reduced to below a certain battery voltage, the reduction process also decomposes the electrolyte. To avoid these processes, the positive and negative electrodes should be selected such that the battery voltage is below or above the decomposition voltage of the electrolyte. Therefore, the electrolyte determines the voltage window within which the rechargeable battery cell can operate reversibly, i.e., be repeatedly charged and discharged.

[0007] Known lithium-ion batteries in the prior art include an electrolyte composed of an organic solvent or solvent mixture and a conductive salt dissolved therein. The conductive salt is a lithium salt, such as lithium hexafluorophosphate (LiPF6). The solvent mixture can include, for example, ethylene carbonate. An example of such an electrolyte is electrolyte LP57, the composition of which is 1M LiPF6 in EC (ethylene carbonate): EMC (ethyl methyl carbonate) 3:7. Due to the organic solvent or solvent mixture, these types of lithium-ion batteries are also referred to as organic lithium-ion batteries.

[0008] The negative electrode of these organic lithium-ion batteries includes a carbon coating, which is applied to a discharge element made of copper. The discharge element provides the required electronic conductive connection between the carbon coating and the external circuit. The associated positive electrode is composed of lithium cobalt oxide (LiCoO2), which is applied to a discharge element made of aluminum. The thickness of both electrodes is usually less than 100 μm and is thus very thin.

[0009] It has long been known that accidental overcharging of organic lithium-ion batteries can lead to irreversible decomposition of the electrolyte components. Oxidative decomposition of the organic solvent and / or the conductive salt occurs on the surface of the positive electrode. The heat of reaction generated during the decomposition process and the gaseous products thus formed are the cause of the subsequent so-called "thermal runaway" and the resulting destruction of the organic lithium-ion battery. The vast majority of the charging protocols for these organic lithium-ion batteries use the battery voltage as an indicator of the end of charging. When using a multi-cell battery pack in which a plurality of organic lithium-ion batteries with different capacities are connected in series, accidents caused by thermal runaway are very likely to occur.

[0010] Lithium is the most electropositive metal (-3.10 V compared to the standard hydrogen electrode, SHE), so all materials react with it reductively, such as the organic electrolytes of organic lithium-ion batteries. The reductive decomposition of the organic electrolyte on this negative electrode is irreversible. There is no organic solvent that is thermodynamically stable with respect to lithium or lithium stored in carbon (Li x C6). However, many solvents form a passivation film on the electrode surface of the negative electrode. This film spatially separates the solvent from the electrode, but it is ionically conductive and thus allows lithium ions to pass through. The passivation film, the so-called "solid electrolyte interface" (SEI), confers stability to the system, making the production of organic lithium-ion batteries possible. During the formation of the SEI, lithium is incorporated into the passivation film. This process is irreversible, and thus a capacity loss is observed. This irreversible capacity loss, also called the coating capacity, depends on the electrolyte formulation and the electrode used. In organic lithium-ion batteries, the electrolyte decomposition and the formation of lithium-ion-containing layers often continue during the further operation of the organic lithium-ion battery and result in capacity loss and thus a shortened service life of the organic lithium battery. Capacity loss can also occur during the storage of organic lithium-ion batteries for electrical energy storage. This so-called self-discharge can be based on irreversible processes such as electrolyte decomposition or on reversible processes that transfer lithium stored in the negative electrode into the electrolyte solution and make it available again during the next charge.

[0011] Therefore, organic lithium-ion batteries have problems with their stability and long-term operational reliability. In particular, the flammability of organic solvents or solvent mixtures also poses a safety risk. When an organic lithium-ion battery catches fire or even explodes, the organic solvents in the electrolyte form combustible substances. Other measures must be taken to avoid such safety risks. These measures include, in particular, very precise regulation of the charging and discharging processes of the organic lithium-ion battery, as well as optimization of the battery design. In addition, organic lithium-ion batteries also include components that melt in the event of an unexpected temperature increase, so that the molten plastic fills the organic lithium-ion battery. This prevents a further uncontrolled increase in temperature. However, these measures lead to an increase in the production costs of organic lithium-ion batteries and an increase in volume and weight. In addition, these measures also reduce the energy density of organic lithium-ion batteries.

[0012] Another disadvantage of organic lithium-ion batteries is that any hydrolysis products produced in the presence of residual water are highly corrosive to the battery components of rechargeable battery cells. For example, the conductive salt LiPF6, which is often used in organic batteries, reacts with trace amounts of water to produce highly reactive and corrosive hydrogen fluoride (HF). Therefore, when manufacturing rechargeable battery cells with an organic electrolyte, care must be taken to minimize the amount of residual water in the electrolyte and battery components. As a result, production is usually carried out in expensive drying chambers with extremely low humidity. The above-mentioned issues regarding stability and long-term operational reliability are particularly important for the development of organic lithium-ion batteries, which are characterized on the one hand by high energy and power density levels and on the other hand by high operational reliability and a long service life, including a large number of available charge and discharge cycles.

[0013] Therefore, further improvements known from the prior art provide for the use of an electrolyte based on sulfur dioxide (SO2) instead of an organic electrolyte for rechargeable battery cells. Rechargeable battery cells containing an SO2-based electrolyte furthermore have high ionic conductivity. The term "SO2-based electrolyte" refers to an electrolyte that contains not only SO2 as a low-concentration additive, but also the mobility of the ions in the conductive salts contained in the electrolyte is at least partially, or even completely, ensured by SO2. Thus, SO2 acts as a solvent for the conductive salt. The conductive salt can form a liquid solvate complex with gaseous SO2, and compared to pure SO2, the SO2 is bound and the vapor pressure is significantly reduced. An electrolyte with a low vapor pressure is produced. Compared to the above-mentioned organic electrolytes, these SO2-based electrolytes have the advantage of being non-flammable. Therefore, the safety risks that may occur due to the flammability of the electrolyte can be excluded.

[0014] For example, EP 2290738B1[V2] describes an SO2-based electrolyte with the composition LiAlCl4*SO2 in combination with a negative electrode made of graphite and a positive electrode made of lithium cobalt oxide (LiCoO2). A disadvantage of the battery cell is the formation of a coating on the graphite during the first cycle of the battery cell, resulting in a loss of capacity. It is pointed out in the translation of paragraph

[0008] of [V1] that

[0015] "[...] a high proportion of lithium contained in the positive electrode (e.g., about 25%) [...] is consumed during the first charging process to form a coating".

[0016] In [V1], this problem is solved by transferring the additional supply of the active metal required for coating formation to one of the electrodes.

[0017] In addition, these SO2-based electrolytes also have a drawback in that any hydrolysis products formed in the presence of residual water react with the cell components of the rechargeable battery cell and thus lead to the formation of undesirable by-products. For this reason, when manufacturing a rechargeable battery cell with an SO2-based electrolyte, care should be taken to minimize the residual water content in the electrolyte and the cell components.

[0018] Another problem with SO2-based electrolytes is that many conductive salts are insoluble in SO2, especially those conductive salts known to be used in organic lithium-ion batteries. Tests have shown that SO2 is a poor solvent for many conductive salts, such as lithium fluoride (LiF), lithium bromide (LiBr), lithium sulfate (Li2SO4), lithium bis(oxalato)borate (LiBOB), lithium hexafluoroarsenate (LiAsF6), lithium tetrafluoroborate (LiBF4), lithium hexafluoroaluminate (Li3AlF6), lithium hexafluoroantimonate (LiSbF6), lithium difluoro(oxalato)borate (LiBF2C2O4), lithium bis(trifluoromethanesulfonyl)imide (LiTFSI), lithium metaborate (LiBO2), lithium aluminate (LiAlO2), lithium trifluoromethanesulfonate (LiCF3SO3), and lithium chlorosulfonate (LiSO3Cl). The solubility of these conductive salts in SO2 is approximately 10 -2 -10 -4 mol / L (see Table 1). At these low salt concentrations, it can be assumed that there is at most only low conductivity, which is not sufficient for the effective operation of the rechargeable battery cell.

[0019] Table 1: Solubility of various conductive salts in SO2

[0020] Summary of the Invention

[0021] In order to further improve the possible uses and performance of rechargeable battery cells containing SO2-based electrolytes, the object of the present invention is to provide a rechargeable battery cell with an SO2-based electrolyte which, compared to the rechargeable battery cells known from the prior art, has the following characteristics:

[0022] - has a wide electrochemical window, so that oxidative electrolyte decomposition does not occur on the positive electrode;

[0023] - has a stable coating layer on the negative electrode, so that the capacity of the coating layer should be low and, during further operation, reductive electrolyte decomposition should no longer occur on the negative electrode;

[0024] - contains an SO2-based electrolyte which exhibits good solubility for conductive salts and is therefore a good ionic conductor and an electronic insulator, thus promoting the transport of ions and reducing self-discharge to a minimum;

[0025] - Containing a SO2-based electrolyte that is also inert to other components of the rechargeable battery unit, such as separators, electrode materials, and battery packaging materials,

[0026] - Being able to resist various improper uses, such as electrical, mechanical, or thermal;

[0027] - Containing a SO2-based electrolyte that exhibits enhanced stability with respect to the residual water content in the battery components of the rechargeable battery unit;

[0028] - Exhibiting improved electrical performance data, especially high energy density;

[0029] - Exhibiting improved overcharge and deep discharge and less self-discharge, and

[0030] - Exhibiting a longer service life, especially a high number of available charge and discharge cycles.

[0031] Such a rechargeable battery unit should in particular also have very good electrical energy and performance data, high operating reliability and service life, especially a large number of available charge and discharge cycles, and the electrolyte does not decompose during the operation of the rechargeable battery unit.

[0032] This object is solved by a rechargeable battery unit having the features of claim 1. Claims 2 to 30 describe advantageous improvements of the rechargeable battery unit according to the invention.

[0033] The rechargeable battery unit according to the invention comprises an active metal, at least one positive electrode, at least one negative electrode, a housing, and an electrolyte. The negative electrode contains an active material selected from the group consisting of

[0034] - Insertion materials made of carbon

[0035] - Intercalation materials that form alloys

[0036] - Embedding materials without carbon, and

[0037] - Conversion active materials.

[0038] The electrolyte is based on SO2 and contains at least one first conductive salt. The first conductive salt has the structure of formula (I).

[0039]

[0040] In formula (I), M is a metal selected from the group consisting of alkali metals, alkaline earth metals, metals of Group 12 of the periodic table, and aluminum. x is an integer from 1 to 3. The substituents R 1 、R 2 、R 3 and R 4Independently of each other, selected from the group consisting of C1-C 10 alkyl, C2-C 10 alkenyl, C2-C 10 alkynyl, C3-C 10 cycloalkyl, C6-C 14 aryl and C5-C 14 heteroaryl. The central atom Z is aluminum or boron.

[0041] In the context of the present invention, the term "insertion material made of carbon" refers to a material made of the carbon element, which has units in which active metal ions can be stored and removed during the operation of a lithium battery. This means that the electrode process can occur not only on the electrode surface but also inside the structure. For example, if a lithium-based conductive salt is used, lithium ions can be stored in the insertion material when the rechargeable battery unit is charged and can be removed therefrom when the rechargeable battery unit is discharged.

[0042] The active materials that form alloys are generally metals, metal alloys, and oxides of metals and metal alloys, which form alloys with active metals (such as lithium). For example, such alloy formation occurs in or on the negative electrode and is substantially reversible. Compared with the insertion material, the active metal in the alloy is not stored in the existing structure. Instead, the active metal is stored through a phase change process. For example, when lithium is used as the active metal, a binary end product containing lithium can be produced. When an alloy is formed, the active material can expand.

[0043] In the context of the present invention, the term "intercalation compound" refers to a subcategory of the above-mentioned insertion materials. The intercalation compound acts as a host matrix, which has interconnected vacancies. During the discharge process of the rechargeable battery unit, ions of the active metal can diffuse into these vacancies and can be stored there. During the deposition of ions of the active metal, only minor or no structural changes occur in the host matrix.

[0044] The conversion active material undergoes a chemical conversion or transformation during the electrode process, resulting in the reversible formation of chemical bonds between the active metal and the active material.

[0045] According to the present invention, the SO2-based electrolyte used in a rechargeable battery cell contains SO2, which not only acts as a low-concentration additive, but at this concentration, SO2 at least partially, to a large extent, or even completely ensures the ionic mobility of a first conductive salt, which is contained in the electrolyte and drives charge transport. The first conductive salt is dissolved in the electrolyte and shows very good solubility therein. It can form a liquid solvate complex with gaseous SO2 and bind to SO2. In this case, compared with pure SO2, the vapor pressure of the liquid solvate complex is significantly reduced, resulting in an electrolyte with a low vapor pressure. However, depending on the chemical structure of the first conductive salt according to formula (I), in the production of the electrolyte according to the present invention, a reduction in vapor pressure may not occur either, which is also within the scope of the present invention. In the last-mentioned case, the electrolyte according to the present invention is preferably produced at low temperature or under pressure. The electrolyte may also include a plurality of conductive salts of formula (I) with different chemical structures from each other.

[0046] In the understanding of the present invention, the term "C1-C 10 alkyl" includes straight-chain or branched saturated hydrocarbon groups having 1 to 10 carbon atoms. These groups particularly include methyl, ethyl, n-propyl, isopropyl, n-butyl, sec-butyl, isobutyl, tert-butyl, n-pentyl, isopentyl, 2,2-dimethylpropyl, n-hexyl, isohexyl, 2-ethylhexyl, n-heptyl, isoheptyl, n-octyl, isooctyl, n-nonyl, n-decyl, etc.

[0047] In the understanding of the present invention, the term "C2-C 10 alkenyl" includes straight-chain or branched unsaturated hydrocarbon groups having 2 to 10 carbon atoms, wherein the hydrocarbon group has at least one C-C double bond. Particularly included are vinyl, 1-propenyl, 2-propenyl, 1-n-butenyl, 2-n-butenyl, isobutenyl, 1-pentenyl, 1-hexenyl, 1-heptenyl, 1-octenyl, 1-nonenyl, 1-decenyl, etc.

[0048] In the understanding of the present invention, the term "C2-C 10 alkynyl" includes straight-chain or branched unsaturated hydrocarbon groups having 2 to 10 carbon atoms, wherein the hydrocarbon group has at least one C-C triple bond. Particularly included are ethynyl, 1-propynyl, 2-propynyl, 1-n-butynyl, 2-n-butynyl, isobutynyl, 1-pentynyl, 1-hexynyl, 1-heptynyl, 1-octynyl, 1-nonynyl, 1-decynyl, etc.

[0049] In the understanding of the present invention, the term "C3-C 10"Cycloalkyl" includes cyclic saturated hydrocarbon groups having 3 to 10 carbon atoms. These groups particularly include cyclopropyl, cyclobutyl, cyclopentyl, cyclohexyl, cycloheptyl, cyclohexyl, cyclononyl, and cyclodecyl.

[0050] In the understanding of the present invention, the term "C6-C 14 "Aryl" includes aromatic hydrocarbon groups having 6 to 14 ring carbon atoms. This group particularly includes phenyl (C6H5 group), naphthyl (C 10 H7 group), and anthryl (C 14 H9 group).

[0051] In the understanding of the present invention, the term "C5-C 14 "Heteroaryl" includes aromatic heteroaryl groups having 5 to 14 ring hydrocarbon atoms, where at least one hydrocarbon atom is replaced by a nitrogen atom, an oxygen atom, or a sulfur atom. These groups particularly include pyrrolyl, furyl, thienyl, pyridyl, pyranyl, thiopyranyl, etc. All of the above hydrocarbon groups are bonded to the central atom according to formula (I) through an oxygen atom.

[0052] The advantage of a rechargeable battery cell having such an electrolyte compared to a rechargeable battery cell having an electrolyte known in the prior art is that the first conductive salt contained therein has a higher oxidation stability, and thus basically does not show decomposition at a higher battery voltage. The electrolyte is antioxidant, preferably up to a high potential of at least 4.0V, preferably up to a high potential of at least 4.4V, more preferably up to a high potential of at least 4.8V, more preferably up to a high potential of at least 5.2V, more preferably up to a high potential of at least 5.6V, and most preferably up to a high potential of at least 6.0V. Therefore, when such an electrolyte is used in a rechargeable battery cell, within the operating potential, that is, within the range between the charge termination voltage and the discharge termination voltage of the two electrodes of the rechargeable battery cell, there is almost no electrolyte decomposition or no electrolyte decomposition. Therefore, the rechargeable battery cell according to the present invention can have a charge termination voltage of at least 4.0V, more preferably at least 4.4V, more preferably at least 4.8V, more preferably at least 5.2V, more preferably at least 5.6V, and most preferably at least 6.0V. The service life of a rechargeable battery cell containing such an electrolyte is significantly longer than that of a rechargeable battery cell containing an electrolyte known in the prior art.

[0053] In addition, a rechargeable battery cell having such an electrolyte is also resistant to low temperatures. For example, at a temperature of -40°C, 61% of the charge capacity can still be discharged. The conductivity of the electrolyte at low temperatures is sufficient to operate the battery cell.

[0054] Furthermore, a rechargeable battery cell having such an electrolyte exhibits increased stability with respect to residual amounts of water. Compared to SO2-based electrolytes known in the prior art, if there is still a small amount of residual water (in the ppm range) in the electrolyte, the electrolyte or the first conductive salt forms hydrolysis products with water, and the corrosiveness of these products to the battery components is significantly reduced. Therefore, compared to the prior art, the importance of anhydrous conditions in SO2-based electrolytes has decreased. These advantages of the electrolyte according to the invention outweigh the disadvantages caused by the fact that the anion size of the first conductive salt according to formula (I) is significantly larger than that of the conductive salts known in the prior art. This larger anion size results in a lower conductivity of the first conductive salt according to formula (I) compared to the conductivity of LiAlCl4.

[0055] Negative electrode

[0056] The following describes beneficial improvements of the rechargeable battery cell according to the invention with respect to the negative electrode:

[0057] A first beneficial improvement of the rechargeable battery cell according to the invention provides that the negative electrode contains a negative electrode active material that forms an alloy with lithium, particularly silicon. In other words, in its function as an active metal, lithium forms an alloy with the alloy-forming active material.

[0058] Another beneficial improvement of the rechargeable battery cell according to the invention provides that the insertion material made of carbon is selected from graphite, natural graphite, synthetic graphite, graphitized mesocarbon microbeads (abbreviation: MCMB), carbon-coated graphite, and amorphous carbon. The insertion material made of the carbon allotrope graphite is preferred. Natural graphite can be designed in sheet form (as a so-called sheet conveyor) or circular. Synthetic graphite, also known as graphitized carbon or electrographite, can be produced by graphitizing non-graphite carbon, or by chemical vapor deposition of hydrocarbons at temperatures above 2500 K, or by decomposition of chemically unstable carbides, or by crystallization from a carbon supersaturated metal melt. Compared to natural graphite, it can be preferably used as an anode material due to its more uniform structure and higher purity. Graphitized mesocarbon microbeads (MCMB) preferably have an approximately spherical structure with a diameter of, for example, 1 - 40 μm, and thus have a low specific surface area. The so-called "soft carbon" includes mesocarbon microbeads. In the scope of the present invention, carbon fibers, such as mesophase pitch-based carbon fibers (abbreviation: MCF) or vapor-grown carbon fibers (abbreviation: VGCF), can be used as possible active electrode materials for the negative electrode. The above amorphous carbon does not have long-range crystalline order. Examples in this regard are graphitizable (soft carbon) and non-graphitizable (hard carbon) carbons.

[0059] Another advantageous improvement of the rechargeable battery cell according to the invention provides that the active material forming the alloy is selected from the group consisting of lithium-storing metals and metal alloys, or from the group consisting of oxides of lithium-storing metals and metal alloys. These preferably include silicon (Si), in particular nanosilicon, microsilicon, silicon nanofibers, germanium (Ge), tin (Sn), SnCo x C y 、SnSi x and the like, as well as their oxides, such as SnO x 、SiO x 、glass oxides of Sn and glass oxides of Si, etc. Oxides having the composition MO x are composed of, for example, a mixture of an element and its oxide, where M represents a metal (such as SiO x ). For example, SiO x is composed of a mixture of components Si, SiO, and SiO2. The weight ratio of each component can vary. The theoretical capacities of these alloy-forming partial anode active materials are detailed in Table 2 below:

[0060] Table 2: Theoretical capacities of alloy-forming negative electrode active materials compared with graphite

[0061] Metal Graphite Li Si Gc Al Sn Lithium-containing compound <![CDATA[LiC6]]> Li <![CDATA[Li 22 Si5]]> <![CDATA[Li 22 Gc5]]> AlLi <![CDATA[Li 22 Sn5]]> <![CDATA[Theoretical capacity (mAh.g -1 )]]> 372 >3800 >3000 1600 993 994

[0062] Another advantageous improvement of the rechargeable battery cell according to the invention provides that the alloy-forming anode active material is a silicon-based anode active material. This material has a very high theoretical capacity.

[0063] Another advantageous improvement of the rechargeable battery cell according to the invention provides that the alloy-forming active material is formed of silicon or of silicon oxide, or of a mixture of silicon and silicon oxide.

[0064] For example, silicon-based anode active materials can be classified into 0D, 1D, 2D, and 3D materials, for example, according to their particle geometry or morphology. 0D silicon materials include, for example, silicon nanoparticles with a particle size <150 nm, which can expand during the electrochemical cycling process without showing any damage. 1D nanorods, nanowires, and nanotubes made of silicon provide good conductivity along one-dimensional transport channels because they are usually directly connected to current conductors in the electrode assembly. 2D silicon materials include, for example, thin films and nanosheets made of silicon, which usually have a high capacity. It is observed here that the reversible capacity and the electrochemical cycling stability increase with the decrease in layer thickness. 3D silicon-based porous structures and networks can adapt to volume changes due to their porous characteristics, thereby maintaining their structural integrity. At the same time, these materials have a higher tap density and thus theoretically have a higher volume capacity than low-dimensional nanostructures.

[0065] Another advantageous improvement of the rechargeable battery cell according to the invention provides that the anode active material alloyed with lithium already contains lithium even before being used in the battery. This so-called prelithiation reduces the capacity loss, for example, due to the formation of a coating during the first cycle.

[0066] Another advantageous improvement of the rechargeable battery cell according to the invention provides that the negative electrode contains at least one alloy-forming anode active material, in particular at least one anode active material alloyed with lithium, and contains at least one insertion material made of carbon. A combination of silicon and / or silicon oxide and graphite is preferred. For example, this includes forming a mechanically stable composite. These materials are embedded in each other. The combination can also be in the form of a loose mixture, i.e., a so-called blend. For example, silicon and graphite can be combined or SiO x and graphite can be combined.

[0067] In another advantageous improvement of the rechargeable battery cell according to the invention, the negative electrode contains a lithium-inserting anode active material that does not contain carbon, such as lithium titanate (e.g., Li4Ti5O 12 ).

[0068] In another advantageous improvement of the rechargeable battery cell according to the invention, the anode active material is a conversion active material selected from

[0069] - the group consisting of manganese oxide (MnO x ), iron oxide (FeO x ), cobalt oxide (CoO x ), nickel oxide (NiO x ), copper oxide (CuO x ), or

[0070] - the group consisting of magnesium hydride (MgH2), titanium hydride (TiH2), aluminum hydride (AlH3), and ternary hydrides based on boron, aluminum, and magnesium, etc.

[0071] Another advantageous improvement of the rechargeable battery cell according to the invention provides that the negative electrode is porous, where the porosity is preferably at most 50%, more preferably at most 45%, more preferably at most 40%, more preferably at most 35%, more preferably at most 30%, more preferably at most 20%, and most preferably at most 10%. The porosity represents the cavity volume relative to the total volume of the negative electrode, where the cavity volume is formed by the so-called pores or cavities. This porosity results in an increase in the internal surface area of the negative electrode. In addition, the porosity reduces the density of the negative electrode and thus its weight. During operation, the individual pores of the negative electrode are preferably completely fillable with the electrolyte.

[0072] Another advantageous improvement of the battery cell according to the invention provides that the negative electrode has a discharge element. This means that, in addition to the active material or the insertion material, the negative electrode further comprises a discharge element. The discharge element is used to achieve the required electronic conductive connection of the negative electrode active material. For this purpose, the discharge element is in contact with the active material participating in the negative electrode reaction. The discharge element may be designed as a plane in the form of a thin metal sheet or a thin metal foil. The thin metal foil preferably has a perforated or reticulated structure. The planar discharge element may also be composed of a plastic film coated with a metal. The thickness of the metal coating is in the range of 0.1 μm to 20 μm. Preferably, the active material of the negative electrode is coated on the surface of the thin metal sheet, the thin metal foil or the plastic foil with a metal coating. The active material can be coated on the front side and / or the back side of the planar discharge element. The thickness of such a planar discharge element is in the range of 5 μm to 50 μm. The thickness of the planar discharge element is preferably in the range of 10 μm to 30 μm. When a planar discharge element is used, the total thickness of the negative electrode can be at least 20 μm, preferably at least 40 μm, particularly preferably at least 60 μm. The maximum thickness is at most 200 μm, preferably at most 150 μm, particularly preferably at most 100 μm. When a planar discharge element is used, based on the coating on one side, the areal specific capacity of the negative electrode is preferably at least 0.5 mAh / cm 2 , wherein the following values are further preferably in the following order: 1 mAh / cm 2 , 3 mAh / cm 2 , 5 mAh / cm 2 , 10 mAh / cm 2 , 15 mAh / cm 2 , 20 mAh / cm 2 .

[0073] Furthermore, it is also possible to design the discharge element in the form of a three-dimensional porous metal structure, particularly in the form of a metal foam. The term "three-dimensional porous metal structure" refers to any structure composed of a metal that extends not only in the length and width of a planar electrode such as a thin metal sheet or a metal foil, but also in its thickness dimension. The three-dimensional porous metal structure has sufficient porosity so that the active material of the negative electrode can be incorporated into the pores of the metal structure. The amount of the incorporated or applied active material is the loading on the negative electrode. When the discharge element is designed in the form of a three-dimensional porous metal structure, particularly in the form of a metal foam, the thickness of the negative electrode is preferably at least 0.2 mm, more preferably at least 0.3 mm, more preferably at least 0.4 mm, more preferably at least 0.5 mm, and most preferably at least 0.6 mm. In this case, the thickness of the electrode is significantly increased compared to the negative electrode, which is the case for organic lithium-ion batteries. Another advantageous embodiment provides that when a three-dimensional discharge element, particularly a three-dimensional discharge element in the form of a metal foam, is used, the areal specific capacity of the negative electrode is preferably at least 2.5 mAh / cm2 , among which the following values are further preferably in this order: 5 mAh / cm 2 , 15 mAh / cm 2 , 25 mAh / cm 2 , 35 mAh / cm 2 , 45 mAh / cm 2 , 55 mAh / cm 2 , 65 mAh / cm 2 , 75 mAh / cm 2 . When the discharge element is three-dimensionally designed in the form of a porous metal structure, especially in the form of metal foam, the amount of the negative electrode active material, i.e., the electrode loading based on the electrode area, is at least 10 mg / cm 2 , preferably at least 20 mg / cm 2 , more preferably at least 40 mg / cm 2 , more preferably at least 60 mg / cm 2 , more preferably at least 80 mg / cm 2 , most preferably at least 100 mg / cm 2 . Such loading of the negative electrode has a positive impact on the charging process and discharging process of the rechargeable battery cell.

[0074] In another advantageous improvement of the battery cell according to the present invention, the negative electrode has at least one binder. The binder is preferably a fluorinated binder, especially polyvinylidene fluoride and / or a terpolymer composed of tetrafluoroethylene, hexafluoropropylene, and vinylidene fluoride. However, the binder can also be a binder composed of polymers, and the polymers are constructed from monomer structural units of conjugated carboxylic acids, or from alkali, alkaline earth, or ammonium salts of the conjugated carboxylic acids, or from combinations thereof. Further, the binder can also be composed of polymers based on monomer styrene and butadiene structural units. Additionally, the binder can also be a binder of carboxymethyl cellulose type. Based on the total weight of the negative electrode, the concentration of the binder in the negative electrode is preferably at most 20 wt%, more preferably at most 15 wt%, more preferably at most 10 wt%, more preferably at most 7 wt%, more preferably at most 5 wt%, and most preferably at most 2 wt%.

[0075] In another advantageous improvement of the battery cell according to the present invention, the negative electrode has at least one conductive additive. The conductive additive should preferably exhibit low weight, high chemical tolerance, and high specific surface area. Examples of the conductive additive are particulate carbon (carbon black, SuperP, acetylene black), carbon fiber (carbon nanotube CNT, carbon (nano) fiber), finely divided graphite, and graphene (nanosheet).

[0076] Electrolyte

[0077] The beneficial improvements of the rechargeable battery unit regarding the SO2-based electrolyte are described below.

[0078] In another beneficial embodiment of the rechargeable battery unit, the substituents R 1 , R 2 , R 3 and R 4 are independently selected from the group consisting of the following groups:

[0079] -C1-C6 alkyl; preferably selected from C2-C4 alkyl; particularly preferably, alkyl selected from 2-propyl, methyl, and ethyl;

[0080] -C2-C6 alkenyl; preferably selected from C2-C4 alkenyl; particularly preferably, alkenyl selected from vinyl and propenyl;

[0081] -C2-C6 alkynyl, preferably selected from C2-C4 alkynyl;

[0082] -C3-C6 cycloalkyl;

[0083] -phenyl; and

[0084] -C5-C7 heteroaryl.

[0085] In the case of this advantageous embodiment of the SO2-based electrolyte, the term "C1-C6 alkyl" includes saturated straight-chain or branched-chain hydrocarbon groups having 1 to 6 hydrocarbon groups, especially methyl, ethyl, n-propyl, isopropyl, n-butyl, sec-butyl, isobutyl, tert-butyl, butyl, n-pentyl, isopentyl, 2,2-dimethylpropyl, n-hexyl, and isohexyl. Among them, C2-C4 alkyl is preferred. C2-C4 alkyl is particularly preferably 2-propyl, methyl, and ethyl.

[0086] In the case of this advantageous embodiment of the SO2-based electrolyte, the term "C2-C6 alkenyl" includes unsaturated straight-chain or branched-chain hydrocarbon groups having 2 to 6 carbon atoms, wherein the hydrocarbon group has at least one C-C double bond. These particularly include vinyl, 1-propenyl, 2-propenyl, 1-n-butene, 2-n-butene, isobutene, 1-pentene, and 1-hexene, and among them, C2-C4 alkenyl is preferred. Vinyl and 1-propenyl are particularly preferred.

[0087] In the case of this advantageous embodiment of the SO2-based electrolyte, the term "C2-C6 alkynyl" includes unsaturated straight-chain or branched-chain hydrocarbon groups having 2 to 6 carbon atoms, wherein the hydrocarbon group has at least one C-C triple bond. These particularly include ethynyl, 1-propynyl, 2-propynyl, 1-n-butynyl, 2-n-butynyl, isobutynyl, 1-pentynyl, and 1-hexynyl. Among them, C2-C4 alkynyl is preferred.

[0088] In the case of this advantageous embodiment of the SO2-based electrolyte, the term "C3-C6 cycloalkyl" includes cyclic saturated hydrocarbon groups having 3 to 6 carbon atoms. These particularly include cyclopropyl, cyclobutyl, cyclopentyl and cyclohexyl.

[0089] In the case of this advantageous embodiment of the SO2-based electrolyte, the term "C5-C7 heteroaryl" includes phenyl and naphthyl.

[0090] In another advantageous embodiment of the rechargeable battery cell, in order to increase the solubility of the first conductive salt in the SO2-based electrolyte, the substituents R 1 、R 2 、R 3 and R 4 are substituted by at least one fluorine atom and / or by at least one chemical group, where the chemical group is selected from the group consisting of C1-C4 alkyl, C1-C4 alkenyl, C2-C4 alkynyl, phenyl and benzyl. The chemical groups C1-C4 alkyl, C2-C4 alkenyl, C2-C4 alkynyl, phenyl and benzyl have the same properties or chemical structure as the hydrocarbon groups described above. Herein, substitution means that the atoms or atomic groups of the substituents R 1 、R 2 、R 3 and R 4 are substituted by fluorine atoms and / or chemical groups.

[0091] At least one of the substituents R 1 、R 2 、R 3 and R 4 can be a CF3 group or an OSO2CF3 group to achieve a particularly high solubility of the first conductive salt in the SO2-based electrolyte.

[0092] In another beneficial improvement of the rechargeable battery cell, the first conductive salt is selected from the group consisting of:

[0093]

[0094] In order to adjust the conductivity and / or other properties of the electrolyte to a desired value, in another advantageous embodiment of the rechargeable battery cell according to the present invention, the electrolyte has at least one second conductive salt different from the first conductive salt according to formula (I). This means that, in addition to the first conductive salt, the electrolyte can also contain one or even more second conductive salts, the chemical composition and chemical structure of which are different from those of the first conductive salt.

[0095] In another advantageous embodiment of the rechargeable battery unit according to the invention, the second conductive salt is an alkali metal compound, in particular a lithium compound. The alkali metal compound or lithium compound is selected from the group consisting of aluminates, halides, oxalates, borates, phosphates, arsenates and gallates. The second conductive salt is preferably lithium tetrahaloaluminate, in particular LiAlCl4.

[0096] Furthermore, in another advantageous embodiment of the rechargeable battery cell according to the present invention, the electrolyte comprises at least one additive. The additive is preferably selected from the group consisting of vinylene carbonate and its derivatives, vinylethylene carbonate and its derivatives, methylethylene carbonate and its derivatives, lithium (bisoxalato) borate, lithium difluoro(oxalato) borate, lithium tetrafluoro(oxalato) phosphate, lithium oxalate, 2-vinylpyridine, 4-vinylpyridine, cyclic exomethylenecarbonates, sultones, cyclic and acyclic sulfonates, acyclic sulfites, cyclic and acyclic sulfinates, organic esters of inorganic acids, acyclic and cyclic alkanes having a boiling point of at least 36 °C at 1 bar, aromatic compounds, halogenated cyclic and acyclic sulfonylimides, halogenated cyclic and acyclic phosphate esters, halogenated cyclic and acyclic phosphines, halogenated cyclic and acyclic phosphites, halogenated cyclic and acyclic phosphazenes, halogenated cyclic and acyclica group consisting of cyclic and acyclic silylamines, halogenated cyclic and acyclic halogenated esters, halogenated cyclic and acyclic amides, halogenated cyclic and acyclic anhydrides, and halogenated organic heterocycles.

[0097] In a further advantageous improvement of the rechargeable battery cell, the electrolyte has the following composition relative to the total weight of the electrolyte composition:

[0098] (i) 5 to 99.4% by weight of sulfur dioxide,

[0099] (ii) 0.6 to 95% by weight of a first conductive salt,

[0100] (iii) 0 to 25% by weight of a second conductive salt, and

[0101] (iv) 0 to 10% by weight of an additive.

[0102] As described above, the electrolyte may contain not only the first conductive salt and the second conductive salt according to formula (I), but also may include a plurality of first conductive salts and a plurality of second conductive salts according to formula (I). In the latter case, the above percentages also include the plurality of first conductive salts and the plurality of second conductive salts. Based on the total volume of the electrolyte, the molar concentration of the first conductive salt is in the range of 0.01 mol / L to 10 mol / L, preferably 0.05 mol / L to 10 mol / L, more preferably 0.1 mol / L to 6 mol / L and most preferably 0.2 mol / L to 3.5 mol / L.

[0103] Another more advantageous improvement of the rechargeable battery cell according to the invention provides that the electrolyte contains at least 0.1 mol of SO2, preferably at least 1 mol of SO2, more preferably at least 5 mol of SO2, more preferably at least 10 mol of SO2, and most preferably at least 20 mol of SO2 per mole of conductive salt. The electrolyte may also contain a very high molar proportion of SO2, where the preferred upper limit is that the electrolyte contains 2600 mol of SO2 per mole of conductive salt, and the further preferred upper limits in this order are that the electrolyte contains 1500, 1000, 500, and 100 mol of SO2 per mole of conductive salt. The term "per mole of conductive salt" refers to all the conductive salts contained in the electrolyte. The electrolyte based on SO2 has such a concentration ratio between SO2 and the conductive salt that, compared with electrolytes known in the prior art, such as those based on organic solvents, the advantage is that more conductive salts can be dissolved. Surprisingly, in the context of the present invention, despite the relatively high associated vapor pressure, an electrolyte with a relatively low concentration of conductive salts is advantageous, especially in terms of stability during many charge and discharge cycles of the rechargeable battery cell. The concentration of SO2 in the electrolyte affects its conductivity. Therefore, by selecting the concentration of SO2, the conductivity of the electrolyte can be adjusted according to the intended use of the rechargeable battery operating with this electrolyte.

[0104] The total content of SO2 and the first conductive salt can be greater than 50% (by weight) of the weight of the electrolyte, preferably greater than 60% by weight, more preferably greater than 70% by weight, more preferably greater than 80% by weight, more preferably greater than 85% by weight, more preferably greater than 90% by weight, more preferably greater than 95% by weight, or most preferably greater than 99% by weight.

[0105] Based on the total amount of the electrolyte contained in the rechargeable battery cell, the electrolyte can contain at least 5% by weight of SO2, where more preferably the values of 20% by weight of SO2, 40% by weight of SO2, and 60% by weight of SO2 can be contained. The electrolyte can also contain up to 95% by weight of SO2, where the preferred maximum values in this order are 80% by weight of SO2 and 90% by weight of SO2.

[0106] Within the scope of the present invention, the electrolyte preferably contains only a very small percentage or even no percentage of at least one organic solvent. For example, the proportion of the organic solvent present in the form of a single solvent or a mixture of solvents in the electrolyte can preferably be at most 50% by weight of the electrolyte. Lower proportions of up to 40% by weight, up to 30% by weight, up to 20% by weight, up to 15% by weight, up to 10% by weight, up to 5% by weight or up to 1% by weight of the electrolyte are particularly preferred. More preferably, the electrolyte does not contain an organic solvent. Due to the low proportion or even complete absence of the organic solvent, the electrolyte is hardly flammable or not flammable at all. This increases the operational safety of the rechargeable battery cell operated with such an SO2-based electrolyte. The SO2-based electrolyte is particularly preferably substantially free of organic solvents.

[0107] In a further advantageous refinement of the rechargeable battery cell, the electrolyte has the following composition relative to the total weight of the electrolyte composition:

[0108] (i) 5 to 99.4% by weight of sulfur dioxide,

[0109] (ii) 0.6 to 95% by weight of a first conductive salt,

[0110] (iii) 0 to 25% by weight of a second conductive salt,

[0111] (iv) 0 to 10% by weight of an additive, and

[0112] (v) 0 to 50% by weight of an organic solvent.

[0113] Active metal

[0114] The following describes advantageous refinements of the rechargeable battery cell according to the present invention with respect to the active metal:

[0115] In a first advantageous refinement of the rechargeable battery cell, the active metal is

[0116] - an alkali metal, in particular lithium or sodium;

[0117] - an alkaline earth metal, in particular calcium;

[0118] - a metal of Group 12 of the periodic table, in particular zinc; or

[0119] - aluminum.

[0120] Positive electrode

[0121] The following describes advantageous refinements of the rechargeable battery cell according to the present invention with respect to the positive electrode:

[0122] A first advantageous improvement of the rechargeable battery cell according to the present invention provides that the positive electrode can be charged to a high potential of at least 4.0 V, preferably to a high potential of 4.4 V, more preferably at least to a high potential of 4.8 V, more preferably at least to a high potential of 5.2 V, more preferably at least to a high potential of 5.6 V, and most preferably at least to a high potential of 6.0 V.

[0123] Another advantageous improvement of the rechargeable battery cell according to the present invention provides that the positive electrode comprises at least one active material. The material can store ions of an active metal and release and absorb ions of the active metal during the operation of the battery cell.

[0124] In another advantageous improvement of the rechargeable battery cell according to the present invention, the positive electrode comprises at least one intercalation compound. In the context of the present invention, the term "intercalation compound" refers to a subcategory of the above-mentioned insertion materials. The intercalation compound serves as a host matrix which has interconnected vacancies. Ions of the active metal can diffuse into these vacancies during the discharge process of the rechargeable battery and can be stored there. During the deposition of the active metal ions, only minor or no structural changes occur in the host matrix.

[0125] In another advantageous improvement of the rechargeable battery cell according to the present invention, the positive electrode comprises at least one conversion compound as the active material. In the sense of the present invention, the term "conversion compound" refers to a material which forms other materials in electrochemically active processes; that is to say, chemical bonds are broken and re-established during the charging and discharging processes of the battery cell. During the absorption or release of the active metal ions, the matrix of the conversion compound undergoes a structural change.

[0126] In another advantageous improvement of the rechargeable battery cell according to the present invention, the active material has the composition of x M' y M" z O a In this composition, x M' y M" z O a

[0127] - A is at least one metal selected from the group consisting of alkali metals, alkaline earth metals, metals of Group 12 of the periodic table or aluminum,

[0128] - M' is at least one metal selected from the group consisting of the metals Ti, V, Cr, Mn, Fe, Co, Ni, Cu and Zn;

[0129] "-M" is an element selected from at least one group consisting of elements of Group 2, Group 3, Group 4, Group 5, Group 6, Group 7, Group 8, Group 9, Group 10, Group 11, Group 12, Group 13, Group 14, Group 15, and Group 16 of the periodic table of elements;

[0130] - x and y are numbers greater than 0 and independent of each other;

[0131] - z is a number greater than or equal to 0; and

[0132] - a is a number greater than 0.

[0133] A is preferably metallic lithium, that is, the compound may have the composition of Li x M' y M" z O a composition.

[0134] A x M' y M" z O a In the composition of, the markers y and z are related to the total number of metals and elements represented by M' and M", respectively. For example, if M' contains two metals M' 1 and M' 2 , then the following applies to the marker y: y = y1 + y2, where y1 and y2 represent the markers of the metals M' 1 and M' 2 . The selection of the markers x, y, z, and a must make the compound electrically neutral. An example of a compound in which M' contains two metals is a lithium nickel manganese cobalt oxide with the composition Li x Ni y1 Mn y2 Co z O2, where M'1 = Ni, M' 2 = Mn, M" = Co. An example of a compound with z = 0, that is, no other metal or element M", is lithium cobalt oxide Li x Co y O a . For example, if M" contains two elements, on the one hand a metal as M"1 and on the other hand phosphorus as M" 2 , the following applies to the marker z: z = z1 + z2, where z1 and z2 represent the markers of the metal M" 1 and phosphorus (M" 2 ). The selection of the markers x, y, z, and a must make the compound electrically neutral. An example of a compound in which A contains lithium, M" is the metal M" 1 and phosphorus is M" 2 is lithium iron manganese phosphate Li x Fe yMn z1 P z2 O4, where A = Li, M' = Fe, M"1 = Mn, M" 2 = P and z2 = 1. In another composition, M" may include two non-metals. For example, fluorine is M" 1 and sulfur is M" 2 . An example of such a compound is lithium iron fluorosulfate Li x Fe y F z1 S z2 O4, where A = Li, M' = Fe, M" 1 = F and M" 2 = P.

[0135] Another beneficial improvement of the rechargeable battery cell according to the present invention provides that M' includes metallic nickel and manganese, and M" is cobalt. Thus, it can be a composition of Li x Ni y1 Mn y2 Co z O2 (NMC), that is, lithium nickel manganese cobalt oxide having a layered oxide chemical structure. Examples of these lithium nickel manganese cobalt oxide active materials are LiNi 1 / 3 Mn 1 / 3 Co 1 / 3 O2 (NMC111), LiNi 0.6 Mn 0.2 Co 0.2 O2 (NMC622) and LiNi 0.8 Mn 0.1 Co 0.1 O2 (NMC811). Other compounds of lithium nickel manganese cobalt oxide can have compositions of LiNi 0.5 Mn 0.3 Co 0.2 O2, LiNi 0.5 Mn 0.25 Co 0.25 O2, LiNi 0.52 Mn 0.32 Co 0.16 O2, LiNi 0.55 Mn 0.30 Co 0.15 O2, LiNi 0.58 Mn 0.14 Co 0.28 O2, LiNi 0.64 Mn 0.18 Co 0.18 O2, LiNi 0.65 Mn 0.27 Co 0.08 O2, LiNi 0.7Mn 0.2 Co 0.1 O2, LiNi 0.7 Mn 0.15 Co 0.15 O2, LiNi 0.72 Mn 0.10 Co 0.18 O2, LiNi 0.76 Mn 0.14 Co 0.10 O2, LiNi 0.86 Mn 0.04 Co 0.10 O2, LiNi 0.90 Mn 0.05 Co 0.05 O2, LiNi 0.95 Mn 0.025 Co 0.025 O2 or a combination thereof. These compounds can be used to produce a positive electrode of a rechargeable battery cell with a battery voltage exceeding 4.6V.

[0136] Another advantageous improvement of the rechargeable battery cell according to the present invention provides that the active material is a lithium- and manganese-rich metal oxide (lithium-rich and manganese-rich oxide material). The metal oxide may have a composition of Li x Mn y M" z O a In the above formula Li x Mn y M" z O a , M' thus represents metallic manganese (Mn). Here, the label x is greater than or equal to 1, the label y is greater than the label z or greater than the sum of the labels z1 + z2 + z3, etc. For example, if M" includes two metals M" 1 and M" 2 , and their labels are z1 and z2 respectively (for example, Li 1.2 Mn 0.525 Ni 0.175 Co 0.1 O2, and M"1 = Ni, z1 = 0.175 and M" 2 = Co, z2 = 0.1), then the following applies to the label y: y > z1 + z2. The label z is greater than or equal to 0, and the label a is greater than 0. The selection of the labels x, y, z, and a must make the compound electrically neutral. The lithium- and manganese-rich metal oxide can also be represented by the formula mLi2MnO3·(1 - m)LiM'O2, where 0 < m < 1. Examples of such compounds are Li 1.2 Mn 0.525 Ni 0.175 Co 0.1 O2, Li1.2 Mn 0.6 Ni 0.2 O2 or Li 1.2 Ni 0.13 Co 0.13 Mn 0.54 O2.

[0137] Another advantageous improvement of the rechargeable battery cell according to the present invention provides a compound having formula A x M' y M" z O4. These compounds are spinel structures. For example, A can be lithium, M' is cobalt and M" is manganese. In this case, the active material is lithium cobalt manganese oxide (LiCoMnO4). LiCoMnO4 can be used to produce the positive electrode of a rechargeable battery cell with a battery voltage exceeding 4.6V. The LiCoMnO4 preferably does not contain Mn3+. In another example, M' can be nickel and M" can be manganese. In this case, the active material is lithium nickel manganese oxide (LiNiMnO4). The molar ratio of the two metals M' and M" can vary. For example, lithium nickel manganese oxide can have the composition LiNi 0.5 Mn 1.5 O4.

[0138] In another advantageous improvement of the rechargeable battery cell according to the present invention, the positive electrode comprises at least one active material constituting a conversion compound. The conversion compound undergoes a solid-state redox reaction during the absorption of an active metal (such as lithium or sodium), in which the crystal structure of the material changes. This occurs through the breaking and re-bonding of chemical bonds. For example, a fully reversible reaction of the conversion compound can be, for example, as follows:

[0139] Type A:

[0140] Type B:

[0141] Examples of conversion compounds are FeF2, FeF3, CoF2, CuF2, NiF2, BiF3, FeCl3, FeCl2, CoCl2, NiCl2, CuCl2, AgCl, LiCl, S, Li2S, Se, Li2Se, Te, I and LiI.

[0142] In another advantageous improvement, the compound has a composition of A x M' y M" z1 M" z2 O4, where M" 2 is phosphorus and the value of z2 is 1. Having a composition of Li x M' y M"z1 M" z2 Compounds of O4 are so-called lithium metal phosphates. In particular, the compounds have the composition Li x Fe y Mn z1 P z2 O4. Examples of lithium metal phosphates are lithium iron phosphate (LiFePO4) or lithium iron manganese phosphate (Li(Fe y Mn z )PO4). An example of lithium iron manganese phosphate is a phosphate having the composition Li(Fe 0.3 Mn 0.7 )PO4. An example of lithium iron manganese phosphate is a phosphate having the composition Li(Fe 0.3 Mn 0.7 )PO4. Lithium metal phosphates of other compositions can also be used in the battery cells according to the present invention.

[0143] Another advantageous improvement of the rechargeable battery cell according to the present invention provides that the positive electrode contains at least one metal compound. The metal compound is selected from the group consisting of metal oxides, metal halides, and metal phosphates. The metal of the metal compound is preferably a transition metal having an atomic number of 22 to 28 in the periodic table of elements, particularly cobalt, nickel, manganese, or iron.

[0144] Another beneficial improvement of the rechargeable battery cell according to the present invention provides that the positive electrode contains at least one metal compound having a chemical structure of spinel, layered oxide, conversion compound, or polyanion compound.

[0145] Within the scope of the present invention, the active material of the positive electrode contains at least one of the said compounds or a combination of the said compounds. A combination of compounds means a positive electrode containing at least two of the said materials.

[0146] Another beneficial improvement of the rechargeable battery cell according to the present invention provides that the positive electrode includes a discharge element. This means that the positive electrode includes a discharge element in addition to the active material. The function of the discharge element is to achieve a required electronic conductive connection for the positive electrode active material. For this purpose, the discharge element is in contact with the active material participating in the positive electrode reaction.

[0147] The discharge element can be designed in the form of a thin metal sheet or a thin metal foil in a planar manner. The thin metal foil preferably has a perforated or reticulated structure. The planar discharge element can also consist of a plastic film coated with metal. The thickness of the metal coating is in the range of 0.1 μm to 20 μm. The positive electrode active material is preferably coated on the surface of the thin metal sheet, the thin metal foil or the metal-coated plastic foil. The active material can be coated on the front side and / or the back side of the planar discharge element. The thickness of such a planar discharge element is in the range of 5 μm to 50 μm. The thickness of the planar discharge element is preferably in the range of 10 μm to 30 μm. When using a planar discharge element, the total thickness of the positive electrode can be at least 20 μm, preferably at least 40 μm, and particularly preferably at least 60 μm. The maximum thickness is at most 200 μm, preferably at most 150 μm, and particularly preferably at most 100 μm. When using a planar discharge element, based on the coating on one side, the areal specific capacity of the positive electrode is preferably at least 0.5 mAh / cm 2 , and the following values are further preferably in this order: 1 mAh / cm 2 , 3 mAh / cm 2 , 5 mAh / cm 2 , 10 mAh / cm 2 , 15 mAh / cm 2 , 20 mAh / cm 2 .

[0148] In addition, the discharge element of the positive electrode can also be designed in the form of a three-dimensional porous metal structure, especially in the form of a metal foam. The three-dimensional porous metal structure has sufficient porosity, so that the active material of the positive electrode can be incorporated into the pores of the metal structure. The amount of the incorporated or coated active material is the loading on the positive electrode. When the discharge element is designed in the form of a three-dimensional porous metal structure, especially in the form of a metal foam, then the thickness of the positive electrode is preferably at least 0.2 mm, more preferably at least 0.3 mm, more preferably at least 0.4 mm, more preferably at least 0.5 mm, and most preferably at least 0.6 mm. Another advantageous embodiment provides that when using a three-dimensional discharge element, especially a positive electrode in the form of a metal foam, the areal specific capacity of the positive electrode is preferably at least 2.5 mAh / cm 2 , and the following values are further preferably in this order: 5 mAh / cm 2 , 15 mAh / cm 2 , 25 mAh / cm 2 , 35 mAh / cm 2 , 45 mAh / cm 2 , 55 mAh / cm 2 , 65 mAh / cm 2 , 75 mAh / cm 2When the discharge element is three-dimensionally designed in the form of a porous metal structure, in particular in the form of metal foam, based on the area of the electrode, the amount of the active material of the positive electrode, i.e., the loading of the electrode, is at least 10 mg / cm 2 , preferably at least 20 mg / cm 2 , more preferably at least 40 mg / cm 2 , more preferably at least 60 mg / cm 2 , more preferably at least 80 mg / cm 2 , most preferably at least 100 mg / cm 2 . Such loading of the positive electrode has a positive effect on the charging process and the discharging process of the rechargeable battery cell.

[0149] In another advantageous improvement of the battery cell according to the invention, the positive electrode comprises at least one binder. The binder is preferably a fluorinated binder, in particular polyvinylidene fluoride and / or a terpolymer composed of tetrafluoroethylene, hexafluoropropylene and vinylidene fluoride. However, it can also be a binder composed of a polymer which is composed of monomer structural units of conjugated carboxylic acids, or composed of alkali metal, alkaline earth metal or ammonium salts of conjugated carboxylic acids, or composed of a combination thereof. In addition, the binder can also be composed of a polymer based on monomer styrene and butadiene structural units. Additionally, the binder can also be a carboxymethyl cellulose-based binder. The binder is pre-set in the positive electrode, and based on the total weight of the positive electrode, its concentration is preferably at most 20% by weight, more preferably at most 15% by weight, more preferably at most 10% by weight, more preferably at most 7% by weight, more preferably at most 5% by weight, and most preferably at most 2% by weight.

[0150] Structure of the rechargeable battery cell

[0151] The following describes advantageous improvements in the structure of the rechargeable battery cell according to the invention:

[0152] To further improve the function of the rechargeable battery cell, another advantageous improvement of the rechargeable battery cell according to the invention provides that the rechargeable battery cell comprises a plurality of negative electrodes and a plurality of positive electrodes, and the plurality of negative electrodes and the plurality of positive electrodes are alternately stacked in the housing. Here, the positive electrode and the negative electrode are preferably electrically isolated from each other by a separator.

[0153] The separator can be composed of non-woven materials, membranes, woven materials, knitted materials, organic materials, inorganic materials, or combinations thereof. Organic separators can consist of unsubstituted polyolefins (such as polypropylene or polyethylene), partially to fully halogenated polyolefins (such as partially to fully fluorinated, especially PVDF, ETFE, PTFE), polyesters, polyamides, or polysulfones. Separators containing organic and inorganic materials are, for example, glass fiber textile materials, where the glass fibers have a suitable polymer coating. The coating preferably contains a fluoropolymer, such as polytetrafluoroethylene (PTFE), ethylene-tetrafluoroethylene (ETFE), perfluoroethylene propylene (FEP), THV (terpolymer of tetrafluoroethylene, hexafluoroethylene, and vinylidene fluoride), perfluoroalkoxy polymer (PFA), aminosilane, polypropylene, or polyethylene (PE). The separator can also be folded in the housing of the battery cell, for example, in the form of a so-called "Z-fold". In this Z-fold, the strip-shaped separator passes through or folds around the electrodes in a Z-shaped manner. Additionally, the separator can also be formed as separator paper.

[0154] Within the scope of the present invention, the separator can be designed as a sheath, where each positive electrode or each negative electrode is covered by the sheath. The sheath can be composed of non-woven materials, membranes, woven materials, knitted materials, organic materials, inorganic materials, or combinations thereof.

[0155] The sheath on the positive electrode makes the ion migration and ion distribution in the rechargeable battery cell more uniform. Especially in the negative electrode, the more uniform the ion distribution, the more active material the negative electrode can potentially carry, and thus the higher the available capacity of the rechargeable battery cell. At the same time, the risks associated with uneven loading and the resulting deposition of active metals are avoided. These advantages are particularly effective when the positive electrode of the rechargeable battery cell is covered in the sheath.

[0156] Preferably, the surface dimensions of the electrode and the sheath can match each other, such that the outer dimensions of the electrode sheath and the outer dimensions of the unsheathed electrode match at least in one dimension.

[0157] The surface area of the sheath can preferably be larger than the surface area of the electrode. In this case, the sheath extends beyond the boundaries of the electrode. The two layers of the sheath covering both sides of the electrode can thus be connected to each other at the edge of the positive electrode by the edge.

[0158] In another advantageous embodiment of the rechargeable battery cell according to the present invention, the negative electrode has a sheath while the positive electrode does not have a sheath.

[0159] Further advantageous features of the present invention will be described and explained in more detail below based on the drawings, examples, and experiments. Description of the Drawings

[0160] Figure 1: Cross-sectional view showing a first embodiment of a rechargeable battery cell according to the present invention;

[0161] Figure 2 : As a detailed illustration, shows Figure 1 An electron microscope image of the three-dimensional porous structure of the metal foam of the first embodiment of

[0162] Figure 3 : Cross-sectional view showing a second embodiment of a rechargeable battery cell according to the present invention;

[0163] Figure 4 : Shows Figure 3 Details of the second embodiment of

[0164] Figure 5 : Exploded view showing a third embodiment of a rechargeable battery cell according to the present invention;

[0165] Figure 6 : Shows the relationship between the potential [V] and the capacity of four test full cells during charging of the negative electrode with graphite 1, graphite 2, graphite 3, and graphite 4 as active electrode materials when forming a coating on the negative electrode;

[0166] Figure 7 : Shows the relationship between the discharge capacity and the number of cycles of three test full cells, which contain graphite 1, graphite 2, and graphite 3 as active electrode materials of the negative electrode;

[0167] Figure 8 : Shows the relationship between the potential [V] and the capacity of two test full cells during charging of the negative electrode with graphite 1 as the active electrode material when forming a coating on the negative electrode, where one reference test full cell is filled with a reference electrolyte and one test full cell is filled with electrolyte 1;

[0168] Figure 9 : Shows the relationship between the discharge capacity and the number of cycles of two test full cells, where the two test full cells contain graphite 1 as the active electrode material of the negative electrode, and one reference test full cell is filled with a reference electrolyte and one test full cell is filled with electrolyte 1;

[0169] Figure 10 : Shows the relationship between the potential [V] and the capacity of three test half cells during charging of the negative electrode with graphite 1, graphite 2, graphite 3, and graphite 4 as active electrode materials when forming a coating on the negative electrode, where the half cells are filled with a reference electrolyte;

[0170] Figure 11: Shows the function relationship between the potential [V] and the capacity of two test full cells during the process of forming a coating on the negative electrode when charging the negative electrode with graphite 1, graphite 2, graphite 3, and graphite 4 as the active electrode material, where one test full cell is filled with electrolyte 3 and one test full cell is filled with electrolyte 4;

[0171] Figure 12 : Shows the function relationship between the potential [V] and the charging percentage during the discharge process of three test full cells, where the three test full cells contain graphite 1 as the negative electrode active material and are filled with electrolytes 1, 3, and 4;

[0172] Figure 13 : Shows that during the process of forming a coating on the negative electrode, when using SiO x 5.0% / graphite 3, SiO x 17.3% / graphite 3, and SiO x 24.0% / graphite 3 mixture as the electrode active material to charge the negative electrode, the function relationship between the potential [V] and the capacity of three test full cells;

[0173] Figure 14 : Shows the function relationship between the discharge capacity and the number of cycles for the first ten cycles during the discharge process of three test full cells, where the three test full cells contain SiO x 5.0% / graphite 3, SiO x 17.3% / graphite 3, and SiO x 24.0% / graphite 3 mixture;

[0174] Figure 15 : Shows the function relationship between the potential [V] and the capacity of four test full cells during the process of forming a coating on the negative electrode when charging the negative electrode with a mixture as the electrode active material. The mixture is a mixture of nanosilicon (5 wt%) and graphite 3 (95 wt%), a mixture of nanosilicon (2.5 wt%) and graphite 1 (97.5 wt%), a mixture of nanosilicon (5.0 wt%) and graphite 1 (95.0 wt%), and a mixture of nanosilicon (10 wt%) and graphite 1 (90 wt%);

[0175] Figure 16 : Shows the function relationship between the discharge capacity and the number of cycles for the first ten cycles during the discharge process of four test full cells. The test full cells contain a mixture of nanosilicon (5 wt%) and graphite 3 (95 wt%), a mixture of nanosilicon (2.5 wt%) and graphite 1 (97.5 wt%), a mixture of nanosilicon (5.0 wt%) and graphite 1 (95.0 wt%), and a mixture of nanosilicon (10 wt%) and graphite 1 (90 wt%) as the active electrode material of the negative electrode;

[0176] Figure 17 : shows the conductivity [mS / cm] of electrolyte 1 as a function of concentration;

[0177] Figure 18 : shows the conductivity [mS / cm] of electrolyte 3 as a function of concentration; and

[0178] Figure 19 : shows the conductivity [mS / cm] of electrolyte 4 as a function of concentration. Detailed Description of the Invention

[0179] Figure 1 Shows a cross-sectional view of a first embodiment of a rechargeable battery cell 2 according to the present invention. The rechargeable battery cell 2 is designed as a prismatic battery and has a housing 1, among other things. The housing 1 encloses an electrode array 3, which includes three positive electrodes 4 and four negative electrodes 5. The positive electrodes 4 and the negative electrodes 5 are stacked alternately in the electrode array 3. However, the housing 1 can also accommodate more positive electrodes 4 and / or negative electrodes 5. Generally, it is preferred that the number of negative electrodes 5 is one more than the number of positive electrodes 4. As a result, the outer end face of the electrode stack is formed by the electrode surface of the negative electrode 5. The electrodes 4, 5 are connected to the corresponding contacts 9, 10 of the rechargeable battery cell 2 through electrode connections 6, 7. The rechargeable battery cell 2 is filled with a SO2-based electrolyte so that the electrolyte penetrates as completely as possible into all the pores or cavities, especially within the electrodes 4, 5. In Figure 1 the electrolyte cannot be seen. In this embodiment, the positive electrode 4 contains an intercalation compound as the active material. The intercalation compound is LiCoMnO4.

[0180] In this embodiment, the electrodes 4, 5 are designed to be flat, that is, layers with a relatively small thickness relative to their surface area. They are each separated from one another by a separator 11. The housing 1 of the rechargeable battery cell 2 is basically designed as a cuboid, wherein the electrodes 4, 5 and the walls of the housing 1 are shown in the cross-sectional view as extending perpendicular to the plane of the drawing and are substantially straight and flat. However, the rechargeable battery cell 2 can also be designed as a wound battery, in which the electrodes consist of thin layers that are wound together with the insulating material. The separator 11 spatially and electrically isolates the positive electrode 4 and the negative electrode 5 on the one hand, and is permeable to active metal ions in particular on the other hand. In this way, a relatively large electrochemically effective surface is generated, which enables a corresponding high-intensity current output.

[0181] The electrodes 4, 5 also have a discharge element for achieving the required electronic conduction connection of the active materials of the respective electrodes. The discharge element is in contact with the active material participating in the electrode reaction of the corresponding electrodes 4, 5 ( Figure 1(not shown in the figure). The discharge element is designed in the form of a porous metal foam 18. The metal foam 18 extends in the thickness dimension of the electrodes 4 and 5. The active materials of the positive electrode 4 and the negative electrode 5 are incorporated into the pores of the metal foam 18, so that the pores of the metal foam are uniformly filled throughout the thickness of the metal structure. The positive electrode 4 contains a binder to improve mechanical strength. The binder is a fluoropolymer. The negative electrode 5 contains carbon as the active material, and the carbon exists in a form suitable as an insertion material for absorbing lithium ions. The structure of the negative electrode 5 is similar to that of the positive electrode 4.

[0182] Figure 2 shows an electron microscope image of the three-dimensional porous structure of the metal foam 18 from Figure 1 the first embodiment. Based on a specified ratio, it can be seen that the average diameter of the pores P is greater than 100 μm, that is to say, it is relatively large. The metal foam is a metal foam made of nickel.

[0183] Figure 3 shows a cross-sectional view of a second embodiment of a rechargeable battery cell 20 according to the present invention. The difference between the second embodiment and Figure 1 the first embodiment shown is that the electrode array includes a positive electrode 23 and two negative electrodes 22. They are separated from each other by a separator 21 and surrounded by a housing 28. The positive electrode 23 has a discharge element 26 in the form of a planar metal foil, and the active material 24 of the positive electrode 23 is coated on both sides of the discharge element 26. The negative electrode 22 also includes a discharge element 27 in the form of a planar metal foil, and the active material 25 of the negative electrode 22 is coated on both sides of the discharge element 27. In addition, the planar discharge element of the edge electrode, that is, the electrode closing the electrode stack, can be coated with the active material only on one side. The uncoated side faces the wall of the housing 28. The electrodes 22 and 23 are connected to the corresponding contacts 31 and 32 of the rechargeable battery cell 20 through electrode connections 29 and 30.

[0184] Figure 4 shows the planar metal foil in Figure 3 the second embodiment, and this planar metal foil 2 is used as the discharge elements 26 and 27 of the positive electrode 23 and the negative electrode 22. The metal foil has a perforated or reticulated structure with a thickness of 20 μm.

[0185] Figure 5 shows an exploded view of a third embodiment of a rechargeable battery cell 40 according to the present invention. The difference between the third embodiment and the above two embodiments is that the positive electrode 44 is surrounded by a sheath 13. In this case, the surface area of the sheath 13 is larger than the surface area of the positive electrode 44, and the boundary 14 of the positive electrode 44 is in Figure 5It is shown by a dashed line in the figure. Two coatings 15, 16 of the sheath 13 covering both sides of the positive electrode 44 are connected to each other at the annular peripheral edge of the positive electrode 44 through an edge connection 17. The two negative electrodes 45 are not encapsulated. The electrodes 44 and 45 can be contacted through electrode connections 46 and 47.

[0186] Example 1 : Preparation of reference electrolyte

[0187] The reference electrolyte for the following examples was prepared according to the method described in the specification of patent EP 2954588B1 (hereinafter referred to as [V2]). First, lithium chloride (LiCl) was vacuum dried at 120 °C for three days. Aluminum particles (Al) were vacuum dried at 450 °C for two days. LiCl, aluminum chloride (AlCl3), and Al were mixed in a glass bottle with an opening to allow gas to escape at an AlCl3:LiCl:Al molar ratio of 1:1.06:0.35. Subsequently, the mixture was subjected to staged heat treatment to prepare a molten salt. After cooling, the formed salt melt was filtered, then cooled to room temperature, and finally SO2 was added until the desired molar ratio of SO2 to LiAlCl4 was reached. The resulting reference electrolyte has the composition LiAlCl4*xSO2, where x depends on the amount of SO2 provided.

[0188] Example 2 : Four embodiments 1, 2, 3, and 4 for preparing a SO2-based electrolyte for a battery cell

[0189] Four embodiments 1, 2, 3, and 4 of a SO2-based electrolyte (hereinafter referred to as electrolyte 1, 2, 3, and 4) were prepared for the following experiments. For this purpose, first, four different first conductive salts according to formula (I) were prepared using the preparation methods described in the following references [V3], [V4], and [V5]:

[0190] [V3],, I. Krossing, Chem. Eur. J. 2001, 7, 490;

[0191] [V4] S.M. Ivanova et al., Chem. Eur. J. 2001, 7, 503;

[0192] [V5] Tsujioka et al., J. Electrochem. Soc., 2004, 151, A1418"

[0193] These four different first conductive salts according to formula (I) will hereinafter be referred to as compounds 1, 2, 3, and 4. They belong to the family of polyfluoroalkoxy aluminates and were prepared in hexane according to the following reaction equation, starting from LiAlH4 and the corresponding alcohol R-OH with R1 = R2 = R3 = R4.

[0194]

[0195] Therefore, using the sum and the structural formula, the following compounds 1, 2, 3, and 4 are obtained:

[0196]

[0197] First, compounds 1, 2, 3, and 4 are recrystallized for purification. Thus, the residue of the segregate LiAlH4 is removed from the first conductive salt because the residue may cause sparks in the presence of trace amounts of water that may be present in SO2.

[0198] Then, compounds 1, 2, 3, and 4 are dissolved in SO2. It is found that compounds 1, 2, 3, and 4 dissolve well in SO2.

[0199] Electrolytes 1, 2, 3, and 4 are prepared according to the following process steps 1 - 4 at low temperature or under pressure:

[0200] 1) Place the corresponding compounds 1, 2, 3, and 4 respectively in a pressure piston with a riser tube,

[0201] 2) Evacuate the pressure piston,

[0202] 3) Allow the inflow of liquid SO2 and

[0203] 4) Repeat steps 2 + 3 until the target amount of SO2 is added.

[0204] The concentrations of compounds 1, 2, 3, and 4 in electrolytes 1, 2, 3, and 4 are 0.6 mol / L (based on the molar concentration of 1 liter of electrolyte), unless otherwise described in the experimental description. The following experiments are carried out using electrolytes 1, 2, 3, and 4 and a reference electrolyte.

[0205] Example 3: Preparation of a test full cell

[0206] The test full cell used in the following experiment is a rechargeable battery unit having two negative electrodes and one positive electrode, with each electrode separated by a separator. The positive electrode contains an active material (named in their respective experiments), a conductive medium, and a binder.

[0207] The negative electrode of the experiment includes an active material, named in their respective experiments. The negative electrode may also contain a binder and / or a conductive additive. The discharge elements of the positive and negative electrodes are made of nickel. Tables 3a and 3b show the active materials tested for the negative electrode.

[0208] Table 3a: Study of graphite as the negative electrode active material

[0209]

[0210] Table 3b: Study of silicon-containing mixtures as negative electrode active materials

[0211] Name Type <![CDATA[SiO x 5.0% / Graphite 3]]> <![CDATA[SiO x (5 wt%) and graphite 3 (95 wt%) mixture]]> <![CDATA[SiO x 17.3% / Graphite 3]]> <![CDATA[SiO x (17.3 wt%) / Graphite 3 (82.7 wt%) mixture]]> <![CDATA[SiO x 24% / Graphite 3]]> <![CDATA[SiO x (24 wt%) / Graphite 3 (76 wt%) mixture]]> Nano-Si 5.0% / Graphite 3 Mixture of nano-silicon (5 wt%) and graphite 3 (95 wt% Si) Nano-Si 2.5% / Graphite 1 Mixture of nano-silicon (2.5 wt%) and graphite 1 (97.5 wt%) Nano Si 5.0% / Graphite 1 Mixture of nano-silicon (5 wt%) and graphite 1 (95 wt%) Nano-Si 10% / Graphite 1 Mixture of nano-silicon (10 wt%) and graphite 1 (90 wt%)

[0212] Each test full cell was filled with the electrolyte required for the experiment, namely the reference electrolyte or electrolytes 1, 2, 3, or 4.

[0213] Several, i.e., two to four, identical test full cells were fabricated for each experiment. The results shown in the experiment are all from the average of the measured values of the same test full cells.

[0214] Example 4 : Measurements in the test full cell

[0215] Coating capacity:

[0216] The capacity consumed to form the coating on the negative electrode during the first cycle is an important criterion for measuring the quality of the battery cell. The coating is formed on the negative electrode during the first charge of the test full cell. Lithium ions are irreversibly consumed to form the coating (coating capacity), so the test full cell has less cycle capacity available for subsequent cycles. The theoretical coating capacity (%) for forming the coating on the negative electrode is calculated according to the following formula:

[0217] Coating capacity [percentage of theory] = (Q lad (x mAh) - Q ent (y mAh)) / Q NEL

[0218] Q lad describes the amount of electricity specified in the corresponding experiment; Q ent describes the amount of electricity obtained when the test full cell is subsequently discharged (in mAh). Q NEL is the theoretical capacity of the negative electrode used. For example, the calculated value of the theoretical capacity in the case of graphite is 372 mAh / g.

[0219] Subtracting the coating capacity (= Q lad (x mAh) - Q ent (y mAh)) from the theoretical capacity of the positive electrode gives the nominal capacity.

[0220] Discharge capacity:

[0221] For example, for measurements in a test full cell, the discharge capacity is determined by the number of cycles. For this purpose, the test full cell is charged to a certain high potential with a certain charging current intensity. The corresponding high potential is maintained until the charging current drops to a certain value. Then, it is discharged to a certain discharge potential with a certain charging current intensity. This charging method is the so-called I / U charging. This process is repeated according to the required number of cycles.

[0222] In the experiment, the high potential or the discharge potential and the corresponding charging or discharging current intensity are given. The value to which the charging current must drop is also described in the experiment.

[0223] The term "high potential" is used as a synonym for the terms "charging potential", "charging voltage", "charging termination voltage", and "upper potential". This term represents the voltage / potential to which a battery (cell) or a storage battery (battery) is charged with the help of a battery charger.

[0224] The storage battery is preferably charged at a current rate of C / 2 and a temperature of 22 °C. By definition, when the charging or discharging rate is 1C, the rated capacity of the battery is charged or discharged within one hour. A charging rate of C / 2 means a charging time of 2 hours.

[0225] The term "discharge voltage" is used synonymously with the term "lower battery voltage". It describes the voltage / potential reached when discharging a battery or a storage battery with the help of a battery charger.

[0226] The battery is preferably discharged at a current rate of C / 2 and a temperature of 22 °C. The discharge capacity is obtained from the discharge current and the time to reach the discharge termination criterion. The relevant graph shows the average value of the discharge capacity, which is a function of the number of cycles. These average values of the discharge capacity are usually normalized to the maximum capacity reached in the corresponding experiment and expressed as a percentage of the rated capacity.

[0227] Experiment 1 : Test full cells using different graphites as the positive electrode active material

[0228] Experiments were conducted in the test full cells according to Example 3 using various graphites as the active material of the negative electrode. On the one hand, the coating capacity (graphite 1, 2, 3, and 4) was determined, and on the other hand, the discharge capacity (graphite 1, 2, and 3) was determined. The test full cells were filled with electrolyte 1 described in Example 2.

[0229] The test full cells include a negative electrode with synthetic graphite described in Table 3a, that is, using graphite 1, graphite 2, graphite 3, or graphite 4 as the active material. The positive electrode contains lithium nickel manganese cobalt oxide (NMC622) (graphite 1, 2, and 3) and lithium iron phosphate (graphite 4) as the active material.

[0230] Figure 6 shows the potential (in V) of the test full cell during charging of the negative electrode as a function of the capacity. The potential is related to the theoretical capacity of the negative electrode. The four curves depicted show the average results of several experiments conducted using the above-described test full cell. Due to the different active materials of the positive electrode, the curve of the test full cell containing graphite 4 is at a slightly lower potential. First, the test full cell is charged at a current of 15 mA until a capacity of 125 mAh (Q lad ) is reached. Then the test full cell is discharged at 15 mA until a potential of 2.5 V is reached. The discharge capacity (Qent) is determined.

[0231] For graphite 1, the determined coating capacity [as a percentage of the theoretical capacity of the negative electrode] is 6.58%, for graphite 2 it is 4.29%, for graphite 3 it is 5.32% and for graphite 4 it is 7.27%. These values are very good compared to existing systems in organic electrolytes.

[0232] In further cycles, the discharge capacity of the test full cells containing graphite 1, 2 and 3 is determined. To determine the discharge capacity (see Example 4), the test full cell is charged at a current intensity of 100 mA to a high potential of 4.4 V. The corresponding high potential is maintained until the charging current drops to 40 mA. Then it is discharged at a current intensity of 100 mA until the discharge potential is 2.5 V.

[0233] Figure 7 shows the average discharge capacity as a function of the number of cycles. The average discharge capacity is normalized to 100% of the initial capacity of the three test full cells. These average discharge capacities are expressed as percentages of the rated capacity. The test full cells containing different graphites show very stable discharge capacity behavior during the number of cycles. In the test full cells containing graphite 1 and graphite 3, 96% of the discharge capacity remains after 250 cycles. The test full cell containing graphite 2 still has 93% of the discharge capacity.

[0234] Experiment 2 : Comparison of the test full cell using electrolyte 1 and the test full cell using the reference electrolyte, with the test full cell using graphite 1 as the negative electrode active material

[0235] Experiments are conducted in two test full cells according to Example 3 using graphite 1 as the anode material. One test full cell is filled with electrolyte 1 described in Example 2, and the other test full cell contains a reference electrolyte with a composition of LiAlCl4×6SO2. The positive electrode contains lithium nickel manganese cobalt oxide (NMC622) as the active material.

[0236] On the one hand, the coating capacity is determined, and on the other hand, the discharge capacity is determined.

[0237] Figure 8 Shows the potential (in V) of the test full cell as a function of capacity when charging the negative electrode. The potential is related to the theoretical capacity of the negative electrode. The two curves depicted show the average results of several experiments conducted using the above-described test full cell. First, the test full cell was charged at a current of 15 mA until a capacity of 125 mAh (Q lad ) was reached. Then the test full cell was discharged at a current of 15 mA until a potential of 2.5 V was reached. The discharge capacity (Q ent ) was determined.

[0238] In the test full cell using Electrolyte 1, the determined coating capacity of Graphite 1 [in % of the negative electrode theoretical capacity] was 6.58%, and in the test full cell using the reference electrolyte, the determined coating capacity of Graphite 1 was 8.30%. The advantage of the combination of Electrolyte 1 and Graphite 1 is the significantly reduced coating capacity.

[0239] The discharge capacity was determined using the same test full cell in further cycles. To determine the discharge capacity (see Example 4), the test full cell was charged at a current intensity of 100 mA to a high potential of 4.4 V. The corresponding high potential was maintained until the charging current dropped to 40 mA. Then it was discharged at a current intensity of 100 mA until the discharge potential was 2.5 V.

[0240] Figure 9 Shows the average discharge capacity as a function of the number of cycles. The average discharge capacity is normalized to 100% of the initial capacity of the two test full cells. These average discharge capacities are expressed as a percentage of the rated capacity.

[0241] The test full cells containing different electrolytes showed different discharge capacity behaviors with respect to the number of cycles. In the test full cell using Electrolyte 1 and Graphite 1, it still had a discharge capacity of 98.4% at the 280th cycle, showing an almost horizontal profile. The test full cell using the reference electrolyte and Graphite 1 still had a discharge capacity of 96.8%, with a slightly further downward trend.

[0242] Experiment 3 : Formation of a coating layer on Graphite 2, Graphite 3, and Graphite 4 in a half cell using the reference electrolyte

[0243] For the preliminary tests on studying the coating capacity, half cell experiments were conducted at room temperature using negative electrodes containing Graphite 2 and Graphite 3 as active materials, and a negative electrode containing Graphite 4 as the active material. The half cell was filled with a reference electrolyte composed of LiAlCl4×1.5SO2 and used a lithium electrode as the reference electrode. Such electrochemical half cell experiments are standard experiments for testing electrode performance data because of their simple structure and low associated experimental workload.

[0244] The half-cell was charged and discharged multiple times at a current intensity of 10 mA (corresponding to 1C of the actual capacity). The coating capacity was calculated from the capacity loss in the first three cycles.

[0245] Figure 10 The coating curves and the associated coating capacities for two half-cell experiments are shown. For the half-cell containing Graphite 2, the coating capacity in the reference electrolyte is 12.1% of the theoretical capacity of the negative electrode, 10.3% for Graphite 3, and 15.5% for Graphite 4. These values are significantly higher compared to the data determined for the same graphite in Electrolyte 1 in Experiment 1.

[0246] Experiment 4 : Graphite 1 as the negative electrode active material in the test full cells using Electrolyte 1, Electrolyte 3, and Electrolyte 4

[0247] A variety of experiments were conducted to study the combinations of Electrolyte 1, 3, and 4 with Graphite 1 as the negative electrode active material. On the one hand, the coating capacities of Electrolyte 3 and 4 were determined, and on the other hand, the discharge capacities of the three electrolytes 1, 3, and 4 were determined.

[0248] To determine the coating capacity, two test full cells were filled with Electrolyte 3 and 4 described in Example 2. The two test full cells contained Graphite 1 as the active material of the negative electrode. The positive electrode contained lithium nickel manganese cobalt oxide (NMC622) as the active material.

[0249] Figure 11 The relationship between the potential (in V) and the capacity of the test full cell during charging of the negative electrode is shown. The potential is related to the theoretical capacity of the negative electrode. The two curves depicted show the average results of multiple experiments conducted on the above test full cells. First, the test full cell was charged at a current of 15 mA until a capacity of 125 mAh (Qlad) was reached. Then the test full cell was discharged at a current of 15 mA until a potential of 2.5 V was reached. The discharge capacity (Qent) was determined.

[0250] The determined coating capacity [in percentage of the theoretical capacity of the negative electrode] is 17.77% in Electrolyte 3 and 20.02% in Electrolyte 4. The coating capacities in Electrolyte 3 and 4 are slightly higher, and the cells containing these electrolytes can also operate very well.

[0251] For the discharge experiment, three test full cells according to Example 3 were filled with electrolytes 1, 3, and 4 described in Example 2. The test full cells contain lithium nickel manganese cobalt oxide (NMC) as the active material of the positive electrode and graphite 1 as the active material of the negative electrode. To determine the discharge capacity (see Example 4), the test full cells were charged at a current intensity of 15 mA until the capacity reached 125 mAh. Then, discharge was carried out at a current intensity of 15 mA until the discharge potential reached 2.5 V.

[0252] Figure 12 The potential curves exceeding the discharge charge during discharge are shown, and the unit is % [maximum charge (discharge) %]. All test full cells have a flat discharge curve, which is necessary for the good operation of the battery cell.

[0253] Experiment 5 : Test the test full cells with a mixture as the negative electrode active material, and the mixture contains SiO x 5.0% / graphite 3, SiO x 17.3% / graphite 3 and SiO x 24.0% / graphite 3

[0254] As can be seen from Table 3b, the term SiO x 5% / graphite 3 represents a mixture of SiO x (5 wt%) and graphite 3 (95 wt%), where SiO x consists of a mixture of components Si, SiO, and SiO2. Further described, the SiO x / graphite 3 mixture has a SiO x content of 17.3 wt% of SiO x , or 24.0 wt% of SiO x and the corresponding amount of graphite 3.

[0255] Three different mixtures were used as the active material of the negative electrode in three test full cells according to Example 3, and experiments were carried out. On the one hand, the coating capacity was determined, and on the other hand, the discharge capacity was determined. The test full cells were filled with electrolyte 1 described in Example 2. The positive electrode contains lithium nickel manganese cobalt oxide as the active material.

[0256] Figure 13 Shows the relationship between the potential (in V) and the capacity of the three test full cells when charging the negative electrode. The potential is related to the theoretical capacity of the negative electrode. The depicted curve shows the average result of multiple experiments using the above test full cells. First, the test full cells were charged at a current of 15 mA until they reached 125 mAh (Q lad) capacity. Then the test full cell was discharged at a current of 15 mA until a potential of 2.5 V was reached. The discharge capacity (Q ent ) was determined.

[0257] For the SiO x 5.0% / graphite 3 mixture, the determined coating capacity [as a percentage of the negative electrode's theoretical capacity] was 12.69%, for SiO x 17.3% / graphite 3 mixture was 15.29%, and for SiO x 24.0% / graphite 3 mixture was 14.41%.

[0258] The discharge capacity was determined in another ten cycles using the same test full cell. To determine the discharge capacity (see Example 4), the test full cell was charged at a current intensity of 40 mA to a high potential of up to 4.4 V. Then it was discharged at a current intensity of 40 mA until the discharge potential was 2.8 V. Figure 14 Shows the relationship between the average discharge capacity of 10 cycles and the number of cycles, with the average discharge capacity normalized to 100% of the initial capacity of the test full cell. The average values of these discharge capacities are expressed as a percentage of the rated capacity. All three cells showed flat discharge capacity curves.

[0259] Experiment 6 : Testing of full cells with nano-silicon / graphite as the negative electrode active material

[0260] Experiments were carried out in the test full cell according to Example 3 using the nano-silicon / graphite mixtures mentioned in Table 3b as the active material of the negative electrode. On the one hand, the coating capacity was determined, and on the other hand, the discharge capacity was determined. The test full cell was filled with electrolyte 1 described in Example 2.

[0261] Four test full cells included negative electrodes containing mixtures that were either a nano-silicon (5 wt%) and graphite 3 (95 wt%) mixture, or a nano-silicon (2.5 wt%) and graphite 1 (97.5 wt%) mixture, or a nano-silicon (5.0 wt%) and graphite 1 (95.0 wt%) mixture, or a nano-silicon (10 wt%) and graphite 1 (90 wt%) mixture. The positive electrode contained lithium nickel manganese cobalt oxide as the active material.

[0262] Figure 15 Shows the relationship between the potential (in V) of the test full cell and the capacity when charging the negative electrode, with the potential related to the theoretical capacity of the negative electrode. The four curves depicted show the average results of multiple experiments carried out using the above test full cell. First, the test full cell was charged at a current of 15 mA until 125 mAh (Q lad) capacity. Then the test full cell was discharged at a current of 15 mA until a potential of 2.8 V was reached. The discharge capacity (Q ent ) was determined.

[0263] For the mixture of nano-silicon (5 wt%) and graphite 3 (95 wt%), the determined coating capacity [as a percentage of the theoretical capacity of the negative electrode] was 12.47%, for the mixture of nano-silicon (2.5 wt%) and graphite 1 (97.5 wt%) it was 9.91%, for the mixture of nano-silicon (5.0 wt%) and graphite 1 (95.0 wt%) it was 11.63%, and for the mixture of nano-silicon (10 wt%) and graphite 1 (90 wt%) it was 14.77%.

[0264] The discharge capacity was determined in another ten cycles using the same test full cell. To determine the discharge capacity (see Example 4), the test full cell was charged to a high potential of up to 4.4 V at a current intensity of 40 mA. Then it was discharged at a current intensity of 40 mA until the discharge potential was 2.8 V. Figure 16 The average of the 10-cycle discharge capacities of three test full cells is shown as a function of the number of cycles. The average of these discharge capacities is expressed as a percentage of the rated capacity. All four cells showed a flat discharge capacity curve.

[0265] Experiment 7 : Determination of the conductivity of electrolytes 1, 3, and 4

[0266] To determine the conductivity, electrolytes 1, 3, and 4 were prepared using different concentrations of compounds 1, 3, and 4. The conductivity of the electrolytes was determined for each concentration of the various compounds using a conductivity measurement method. After temperature control, the two-electrode sensor was kept in contact with the solution and measurements were made in the measurement range of 0 - 50 mS / cm. During the measurement, it was found that the sensor could react with the electrolyte solution containing SO2.

[0267] Figure 17 The relationship between the conductivity of electrolyte 1 and the concentration of compound 1 is shown. When the concentration of compound 1 is 0.6 mol / L - 0.7 mol / L, it can be found that the conductivity reaches a maximum value, which is about 37.9 mS / cm. In contrast, for the organic electrolyte known in the prior art, such as LP30 (1M LiPF6 / EC - DMC (1:1 by weight)), its conductivity is only about 10 mS / cm.

[0268] Figure 18 (Electrolyte 3) and 19 (Electrolyte 4) show the determined conductivity values of electrolytes 3 and 4 at different concentrations.

[0269] For electrolyte 4, a maximum value of 18 mS / cm was reached at a conductive salt concentration of 1 mol / L. Electrolyte 3 showed a maximum conductivity of 0.5 mS / cm at a conductive salt concentration of 0.6 mol / L. Although electrolyte 3 showed a lower conductivity, it was fully feasible to charge or discharge the test full cell as in Experiment 4.

[0270] Experiment 8 : Low-temperature characteristics

[0271] Two test full cells according to Example 3 were prepared to determine the low-temperature characteristics of electrolyte 1 compared to a reference electrolyte. One test full cell was filled with the reference electrolyte having the composition LiAlCl4*6SO2, while the other test full cell was filled with electrolyte 1. The test full cell containing the reference electrolyte included lithium iron phosphate (LEP) as the active material, and the test cell containing electrolyte 1 included lithium nickel manganese cobalt oxide (NMC) as the active material of the positive electrode. Both test full cells included graphite 1 as the active material of the negative electrode. The test full cells were charged to 3.6 V (LEP) or 4.4 V (NMC) at 20°C. And were discharged again to 2.5 V at each temperature to be studied. The discharge capacity reached at 20°C was defined as 100%. The discharge temperature was decreased in temperature steps of 10°K. The discharge capacity reached was expressed as a percentage of the discharge capacity at 20°C. Since the low-temperature discharge is almost independent of the active materials used for the positive and negative electrodes, the results can be transferred to all combinations of active materials. Table 4 shows the results.

[0272] Table 4: Relationship between discharge capacity and temperature

[0273] Temperature Discharge capacity of electrolyte 1 Discharge capacity of reference electrolyte 20℃ 100％ 100％ 10℃ 99％ 99％ 0℃ 95％ 46％ -10℃ 89％ 21％ -20℃ 82％ n / a -30℃ 73％ n / a -35℃ 68％ n / a -40℃ 61％ n / a

[0274] The test full cell containing electrolyte 1 showed very good low-temperature characteristics. A capacity of 82% was reached at -20°C and 73% at -30°C. Even at a temperature of -40°C, 61% of the capacity could still be released. In contrast, the test full cell containing the reference electrolyte showed a discharge capacity only down to -10°C. A capacity of 21% was reached here. The cell containing the reference electrolyte could no longer be discharged at lower temperatures.

Claims

1. A rechargeable battery cell (2, 20, 40) comprising an active metal, at least one positive electrode (4, 23, 44), at least one negative electrode (5, 22, 45), a housing (1, 28) and an electrolyte, The negative electrode contains an active material selected from the group consisting of - insertion materials made of carbon, - active materials forming alloys, - intercalation materials without carbon, and - conversion active materials, And, based on the total weight of the electrolyte composition, the electrolyte is based on SO2 and contains (i) 5 to 99.4% by weight of sulfur dioxide (SO2), (ii) 0.6 to 95% by weight of at least one first conductive salt, (iii) 0 to 25% by weight of at least one second conductive salt, and (iv) 0 to 10% by weight of at least one additive And the at least one first conductive salt has the formula (I), - M is a metal selected from the group consisting of alkali metals, alkaline earth metals, metals of Group 12 of the periodic table and aluminum; - x is an integer from 1 to 3; - Substituent R 1 , R 2 , R 3 and R 4 are each independently selected from the group consisting of C1 - C 10 alkyl, C2 - C 10 alkenyl, C2 - C 10 alkynyl, C3 - C 10 cycloalkyl, C6 - C 14 aryl and C5 - C 14 heteroaryl; and - Z is aluminum or boron.

2. The rechargeable battery cell (2, 20, 40) according to claim 1, Among them, The carbon insertion materials are selected from the group consisting of - graphite, - natural graphite, especially flaky or round natural graphite, - synthetic graphite, especially mesophase graphite, - graphitized mesophase carbon microbeads, - carbon-coated graphite and - amorphous carbon.

3. The rechargeable battery cell (2, 20, 40) according to claim 1 or 2, Among them, The active materials forming alloys are selected from - the group consisting of metals and metal alloys that store lithium, preferably Si, Ge, Sn, SnCo x C y and SnSi x , or - A group consisting of oxides of metals storing lithium and oxides of metal alloys, preferably SnO x , SiO x and oxidized glasses of Sn, oxidized glasses of Si.

4. The rechargeable battery cell (2, 20, 40) according to claim 1, Among them, The active material forming an alloy is formed of silicon, or of silicon oxide, or of a mixture of silicon and silicon oxide.

5. The rechargeable battery cell (2, 20, 40) according to claim 1, Among them, The negative electrode (5, 22, 45) contains at least one anode active material forming an alloy, especially at least one anode active material forming an alloy with lithium, and contains at least one insertion material made of carbon, preferably a combination of silicon and / or silicon oxide and graphite.

6. The rechargeable battery cell (2, 20, 40) according to any one of claims 1 to 3, Among them, The carbon-free intercalation material is lithium titanate, especially Li4Ti5O 12 .

7. The rechargeable battery cell (2, 20, 40) according to any one of claims 1 to 4, Among them, The conversion active materials are selected from - Consisting of the group of manganese oxide (MnO x ), iron oxide (FeO x ), cobalt oxide (CoO x ), nickel oxide (NiO x ), and copper oxide (CuO x ), or - the group consisting of magnesium hydride (MgH2), titanium hydride (TiH2), aluminum hydride (AlH3) and boron-based, aluminum-based and magnesium-based ternary hydrides.

8. The rechargeable battery cell (2, 20, 40) according to any one of the preceding claims, Among them, The positive electrode (4, 23, 44) includes at least one compound as an active material, and the compound preferably has a composition of A x M' y M" z O a , wherein - A is at least one metal selected from the group consisting of alkali metals, alkaline earth metals, metals of Group 12 of the periodic table or aluminum, - M' is at least one metal selected from the group consisting of the elements Ti, V, Cr, Mn, Fe, Co, Ni, Cu and Zn; "-M" is at least one element selected from the group consisting of elements of Group 2, Group 3, Group 4, Group 5, Group 6, Group 7, Group 8, Group 9, Group 10, Group 11, Group 12, Group 13, Group 14, Group 15, and Group 16 of the Periodic Table of the Elements; -x and y are each independently a number greater than 0; -z is a number greater than or equal to 0; and -a is a number greater than 0.

9. The rechargeable battery cell (2, 20, 40) according to claim 8, Among them, The compound has Li x M' y M" z O a composition, where M' is manganese, M" is cobalt, and wherein x, y, and z are preferably equal to 1 and a is preferably equal to 4.

10. The rechargeable battery cell (2, 20, 40) according to claim 8 or 9, Among them, The compound has Li x M' y M" z O a composition, where M' includes nickel and manganese, M" is cobalt, and its formula is Li x Ni y1 Mn y2 Co z O a .

11. The rechargeable battery cell (2, 20, 40) according to claim 8, Among them, The compound has Li x M' y M" 1 z1 M" 2 z2 a composition of O4, where M" 2 is phosphorus and the value of z2 is 1.

12. The rechargeable battery cell (2, 20, 40) according to claim 11, Among them, The compound has Li x M' y M" 1 z1 a composition of PO4, where M' is iron and M" 1 z1 is manganese Wherein the compound preferably has the composition of Li(Fe 0.3 Mn 0.7 )PO4.

13. The rechargeable battery cell (2, 20, 40) according to any one of the preceding claims, Among them, The substituents R of the first conductive salt 1 , R 2 , R 3 and R 4 are each independently selected from the group consisting of the following groups -C1-C6 alkyl; preferably selected from C2-C4 alkyl; particularly preferably alkyl selected from 2-propyl, methyl, and ethyl; -C2-C6 alkenyl; preferably selected from C2-C4 alkenyl; particularly preferably alkenyl selected from vinyl and propenyl; -C2-C6 alkynyl; preferably selected from C2-C4 alkynyl; -C3-C6 cycloalkyl; -phenyl; and -C5-C7 heteroaryl.

14. The rechargeable battery cell (2, 20, 40) according to any one of the preceding claims, Among them, The substituent R of the first conductive salt 1 , R 2 , R 3 and R 4 is substituted by at least one fluorine atom and / or at least one chemical group selected from the group consisting of C1-C4 alkyl, C2-C4 alkenyl, C2-C4 alkynyl, phenyl and benzyl.

15. The rechargeable battery cell (2, 20, 40) according to any one of the preceding claims, Among them, The substituent R of the first conductive salt 1 , R 2 , R 3 and R 4 at least one of which is a CF3 group or an OSO2CF3 group.

16. The rechargeable battery cell (2, 20, 40) according to any one of the preceding claims, Among them, The first conductive salt is selected from the group consisting of the following substances 17. The rechargeable battery cell (2, 20, 40) according to any one of the preceding claims, Among them, The at least one second conductive salt is different from the first conductive salt according to formula (I) and is lithium tetrachloroaluminate.

18. The rechargeable battery cell (2, 20, 40) according to claim 17, Among them, The second conductive salt of the electrolyte is an alkali metal compound, particularly a lithium compound, which is selected from the group consisting of aluminates, halides, oxalates, borates, phosphates, arsenates, and gallates.

19. The rechargeable battery cell (2, 20, 40) according to claim 17 or 18, Among them, The second conductive salt of the electrolyte is lithium tetrachloroaluminate.

20. The rechargeable battery cell (2, 20, 40) according to claim 19, Among them, The additive of the electrolyte is selected from the group consisting of vinylene carbonate and its derivatives, ethylene vinylene carbonate and its derivatives, methyl ethylenecarbonate and its derivatives, lithium (bis(oxalato))borate, lithium difluoro(oxalato)borate, lithium tetrafluoro(oxalato)phosphate, lithium oxalate, 2-vinylpyridine, 4-vinylpyridine, cyclic exomethylene carbonate, sultone, cyclic and acyclic sulfonate esters, acyclic sulfite esters, cyclic and acyclic sulfinate esters, organic esters, inorganic acids, acyclic and cyclic alkanes having a boiling point of at least 36 °C at 1 bar, aromatic compounds, halogenated cyclic and acyclic sulfonimides, halogenated cyclic and acyclic phosphate esters, halogenated cyclic and acyclic phosphines, halogenated cyclic and acyclic phosphite esters, halogenated cyclic and acyclic phosphazenes, halogenated cyclic and acyclic silylamines, halogenated cyclic and acyclic halogenated esters, halogenated cyclic and acyclic amides, halogenated cyclic and acyclic acid anhydrides, and halogenated organic heterocycles.

21. The rechargeable battery cell (2, 20, 40) according to any one of the preceding claims, Among them, Based on the total volume of the electrolyte, the molar concentration of the first conductive salt is in the range of 0.01 mol / L to 10 mol / L, preferably in the range of 0.05 mol / L to 10 mol / L, more preferably in the range of 0.1 mol / L to 6 mol / L, and most preferably in the range of 0.2 mol / L to 3.5 mol / L.

22. The rechargeable battery cell (2, 20, 40) according to any one of the preceding claims, Among them, The electrolyte contains at least 0.1 mol of SO2 per mole of conductive salt, preferably at least 1 mol of SO2, more preferably at least 5 mol of SO2, more preferably at least 10 mol of SO2, and most preferably at least 20 mol of SO2.

23. The rechargeable battery cell (2, 20, 40) according to any one of the preceding claims, Among them, The active metal is - an alkali metal, especially lithium or sodium; - an alkaline earth metal, especially calcium; - a metal selected from Group 12 of the periodic table, especially zinc; or - aluminum.

24. The rechargeable battery cell (2, 20, 40) according to any one of the preceding claims, Among them, The positive electrode (4, 23, 44) includes at least one metal compound selected from the group consisting of metal oxides, metal halides, and metal phosphates, wherein the metal in the metal compound is preferably a transition metal having an atomic number of 22 to 28 in the periodic table, especially cobalt, nickel, manganese, or iron.

25. The rechargeable battery cell (2, 20, 40) according to any one of the preceding claims, Among them, The positive electrode (4, 23, 44) includes at least one of the metal compounds having a chemical structure of spinel, a chemical structure of layered oxide, a chemical structure of conversion compound, or a chemical structure of polyanion compound.

26. The rechargeable battery cell (2, 20, 40) according to any one of the preceding claims, Among them, The positive electrode (4, 23, 44) and / or the negative electrode (5, 22, 45) has a discharge element (26, 27), and the discharge element (26, 27) is preferably formed as a plane in the form of a metal sheet or metal foil, or - three-dimensionally in the form of a porous metal structure, in particular in the form of a metal foam (18).

27. The rechargeable battery cell (2, 20, 40) according to any one of the preceding claims, Among them, The positive electrode (4, 23, 44) and / or the negative electrode (5, 22, 45) comprises at least one binder, preferably a fluorinated binder, in particular polyvinylidene fluoride and / or a terpolymer made of tetrafluoroethylene, hexafluoropropylene and vinylidene fluoride, or a binder composed of a polymer, the polymer being constructed from monomer structural units of a conjugated carboxylic acid, or an alkali metal, alkaline earth metal or ammonium salt of the conjugated carboxylic acid, or a combination thereof, or a binder composed of a polymer based on monomer styrene and butadiene structural units, or a binder of the carboxymethyl cellulose type, wherein, based on the total weight of the positive electrode, the binder is preferably present at a concentration of at most 20% by weight, more preferably at a concentration of at most 15% by weight, more preferably at a concentration of at most 10% by weight, more preferably at a concentration of at most 7% by weight, more preferably at a concentration of at most 5% by weight, and most preferably at a concentration of at most 2% by weight.

28. The rechargeable battery cell (2, 20, 40) according to any one of the preceding claims, comprises a plurality of the negative electrodes (5, 22, 45) and a plurality of the positive electrodes (4, 23, 44), and the plurality of the negative electrodes (5, 22, 45) and the plurality of the positive electrodes are alternately stacked in the housing (1, 28), wherein the positive electrode (4, 23, 44) and the negative electrode (5, 22, 45) are preferably electrically isolated from each other by a separator (11).

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