RU2772791C1 - Battery cell element - Google Patents

Abstract

FIELD: battery cells.

SUBSTANCE: invention relates to a battery cell containing an electrolyte based on SO₂. Battery cell (2, 20, 40) contains active metal, at least one positive electrode (4, 23, 44), at least one negative electrode (5, 22, 45), housing (1, 28) and electrolyte , wherein the negative electrode (5, 22, 45) contains an active material selected from the group consisting of a carbon inclusion material, an alloy-forming active material, a carbon-free intercalary material, and a conversion active material, wherein the electrolyte is based on SO₂ and contains at least one conductive salt.

EFFECT: good electrical energy and performance characteristics, high operational reliability and durability, in particular, a large number of useful charge and discharge cycles without electrolyte decomposition during operation of a rechargeable battery cell, resistance to low temperatures.

30 cl, 19 dwg, 4 tbl, 4 ex

Description

The invention relates to a battery cell containing an electrolyte based on SO ₂ .

Battery cells are of great importance for many areas of technology. They are often used in applications where only small, relatively low amperage battery cells are required, such as when using mobile phones. However, there has also been an increased demand for larger rechargeable battery cells for high energy applications, with ultra-large energy storage in the form of battery cells for electric vehicle drive being of particular importance.

An important requirement for such rechargeable battery cells is a high energy density. This means that the battery cell must have as much electrical energy as possible per unit weight and volume. In this case, lithium as the active metal has proven to be particularly preferred. The active metal of a battery cell is a metal whose ions, during charging or discharging the cell, move in the electrolyte towards the negative or positive electrode, participating there in electrochemical processes. These electrochemical processes lead to the direct or indirect donation of electrons to an external electrical circuit or to the entry of electrons from an external electrical circuit. Battery cells with lithium as the active metal are also called lithium-ion cells. The energy density in such lithium-ion cells can be increased either by increasing the specific capacitance of the electrodes or by increasing the cell voltage.

Both the positive and negative electrodes of the lithium-ion cells are made as switching electrodes. The term "switching electrode" in the sense of the present invention refers to electrodes containing a crystal structure into which active material ions enter and leave during operation of a lithium ion cell. This means that electrode processes can occur not only on the electrode surface, but also inside the crystal structure.

During the charging of a lithium-ion cell, active metal ions exit the positive electrode and enter the negative electrode. When a lithium-ion cell is discharged, the reverse process occurs.

The electrolyte is also an important functional element of any battery cell. It contains in most cases a solvent or mixture of solvents and at least one salt that increases the electrical conductivity of the electrolyte. For example, solid electrolytes or ionic liquids do not contain solvents, but only a salt that increases the electrical conductivity of the electrolyte. The electrolyte is in contact with the positive and negative electrodes of the battery cell. At least one ion of the salt that increases the electrical conductivity of the electrolyte (anion or cation) has such mobility within the electrolyte that, as a result of ionic conduction, the charge transfer between the electrodes necessary for the functioning of the battery cell can occur. Starting from a certain upper battery cell voltage, the electrolyte decomposes electrochemically due to oxidation. This process often leads to the irreversible destruction of the electrolyte components and consequently to the failure of the battery cell. Also, recovery processes can cause decomposition of the electrolyte, starting from a certain lower cell voltage. To prevent these processes, the positive and negative electrodes are selected so that the cell voltage is lower or higher than the electrolyte decomposition voltage. Thus, the electrolyte determines the voltage range within which the battery cell can be reversibly operated, i.e. repeatedly charged and discharged.

Lithium-ion cells known from the prior art contain an electrolyte consisting of an organic solvent or a mixture of organic solvents and a salt dissolved in it, which increases the electrical conductivity of the electrolyte. The conductive salt is a lithium salt, such as lithium hexafluorophosphate (LiPF ₆ ). The solvent mixture may contain, for example, ethylene carbonate (EC). Electrolyte LP57, having a composition of 1 M LiPF ₆ in EC:EMC (ethyl methyl carbonate) 3:7, is an example of such an electrolyte. Due to the presence of an organic solvent or a mixture of organic solvents, this type of lithium ion cells are also called organic lithium ion cells. The negative electrode of such organic lithium-ion cells consists of a carbon coating deposited on a copper discharge cell. The discharge element creates an electrically conductive connection of the carbon coating to an external electrical circuit. The corresponding positive electrode consists of lithium cobalt oxide (LiCoO ₂ ) deposited on an aluminum discharge cell. Both electrodes are typically less than 100 µm thick and therefore very thin.

It has long been known that undesirable overcharging of organic lithium-ion cells leads to irreversible decomposition of electrolyte components. When this occurs, the oxidative decomposition of the organic solvent and/or the salt that increases the electrical conductivity of the electrolyte on the surface of the positive electrode. The heat of reaction generated during this decomposition and the resulting gaseous products are the cause of the subsequent so-called "thermal breakdown" and the resulting destruction of the organic lithium-ion cell. In the vast majority of charging protocols for such lithium-ion cells, the cell voltage appears as an indicator of the end of charging. However, accidents due to thermal runaway are especially likely in the case of using a set of multi-cell batteries in which a plurality of organic lithium-ion cells with a mismatched capacity are connected in series.

Lithium is the most electronegative metal (-3.10 V vs. Standard Hydrogen Electrode, SHE) and therefore all materials on it are converted due to reduction, for example, including organic lithium-ion cell organic electrolytes. This reductive decomposition of the organic electrolyte at the negative electrode is irreversible. None of the organic solvents is thermodynamically stable with respect to lithium or with respect to lithium accumulated in carbon (Li _x C ₆ ). However, many solvents form a passivating film on the surface of the negative electrode. This film spatially separates the solvent from the electrode, but is ion-conductive, thus allowing the passage of lithium ions. The passivating film, the so-called solid electrolyte interphase (SEC), provides stability to the system, making it possible to obtain organic lithium-ion cells. During the formation of TEI, lithium is incorporated into the passivating film. This process is irreversible, due to which there is a loss of capacity. This irreplaceable loss of capacitance, also referred to as capacitance, depends on the electrolyte composition used and on the electrodes used. Often in organic lithium ion cells, the decomposition of the electrolyte and the formation of layers containing lithium ions continues during the subsequent operation of the organic lithium ion cell and causes loss of capacity and hence shorter life of the organic lithium ion cell. Also, when storing charged organic lithium-ion cells, capacity loss can occur. This so-called self-discharge can underlie both irreversible processes, such as, for example, the decomposition of the electrolyte, and reversible processes, in which the lithium accumulated in the negative electrode passes into the electrolyte solution and is used again during subsequent charging.

Therefore, organic lithium-ion cells are problematic in terms of their durability and long-term operational reliability. Reliability risks also arise in particular from the flammability of the organic solvent or solvent mixtures. When an organic lithium ion cell ignites or even explodes, the organic electrolyte solvent forms a combustible material. Additional measures are needed to avoid such reliability risks. These measures include, in particular, a very precise regulation of the charging and discharging processes of the organic lithium-ion cell, as well as an optimized battery design. In addition, the organic lithium ion cell contains components that will melt if the temperature rises unintentionally, and the organic lithium ion cell may leak along with the molten polymer. As a result, an additional uncontrolled increase in temperature is eliminated. However, such measures lead to an increase in production costs in the manufacture of an organic lithium ion cell, as well as an increase in volume and weight. In addition, these measures reduce the energy density of the organic lithium-ion cell.

Another disadvantage of organic lithium ion cells is that hydrolysis products likely to form in the presence of residual water are very aggressive towards the components of the rechargeable battery cell. So, for example, with the LiPF ₆ salt, which is often used in organic cells, which increases the electrical conductivity of the electrolyte, very reactive, aggressive hydrogen fluoride (HF) is formed as a result of reaction with traces of water. Therefore, in the manufacture of such organic electrolyte battery cells, care must be taken to minimize residual water contained in the electrolyte and cell components. Therefore, production is often carried out in expensive drying chambers with extremely low air humidity. The problems described above regarding durability and long-term reliability are of particular importance in the development of organic lithium-ion cells, which have, firstly, very good electrical energy and power characteristics and, secondly, very high operational reliability and durability, in in particular, a very large number of useful charge and discharge cycles.

A prior art improvement involves the use of an electrolyte based on sulfur dioxide (SO ₂ ) instead of an organic electrolyte for battery cells. A battery cell containing an electrolyte based on SO ₂ has, inter alia, high ionic conductivity. The term ''SO ₂ -based electrolyte'' is to be understood as an electrolyte in which SO ₂ is not only contained as an additive in a low concentration, but also in which the ion mobility of the salt that increases the electrical conductivity of the electrolyte contained in the electrolyte and causes charge transfer is ensured , at least partially, mostly or even completely due to SO ₂ . Hence SO ₂ serves as a solvent for said salt. This salt can form a solvate complex with gaseous SO ₂ , whereby SO ₂ binds and the vapor pressure is markedly reduced compared to pure SO ₂ . Electrolytes with low vapor pressure are formed. Such electrolytes based on SO ₂ have the advantage of incombustibility compared to the organic electrolyte described above. Reliability risks caused by the flammability of the electrolyte can therefore be eliminated.

For example, from EP 2290738 B1 (V1) describes an SO ₂ based electrolyte with the composition LiAlCl ₄ * SO ₂ in combination with a graphite negative electrode and a lithium cobalt oxide (LioO ₂ ) positive electrode. A negative aspect of the battery cell is the formation of a coating layer on the graphite during the first charge cycle of the battery cell and the associated loss of capacity. From paragraph [0008] of source (V1) it follows that

''... a large proportion of the lithium contained in the positive electrode before the start of the charging process (for example, about 25%) was consumed during the first charge to form a coating layer''. In the source (V1), this problem is solved due to the fact that the active metal necessary for the formation of the coating layer is supplied to one of the electrodes from an additional reserve.

A disadvantage that also occurs with such an SO ₂ -based electrolyte is that possible hydrolysis products formed in the presence of residual amounts of water react with the components of the battery cell and cause the formation of undesirable by-products. Therefore, in the manufacture of such battery cells with an electrolyte based on SO ₂ care must be taken to minimize the residual water contained in the electrolyte and cell components.

Another typical problem for an electrolyte based on SO ₂ is that many, in particular, conductive salts known from organic lithium-ion cells that increase the electrical conductivity of the electrolyte, are insoluble in the SO ₂ medium. Measurements have shown that SO ₂ is a poor solvent for many conductive salts, for lithium fluoride (LiF), lithium bromide (LiBr), lithium sulfate (Li ₂ SO ₄ ), lithium bis-(oxalato)borate (LiBOB), lithium hexafluoroarsenate ( LiAsF ₆ ), lithium tetrafluoroborate (LiBF ₄ ), trilithium hexafluoroaluminate (LisAlF ₆ ), lithium hexafluoroantimonate (LiSbF ₆ ), lithium difluoro(oxalato)borate (LiBF ₂ C ₂ O ₄ ), lithium bis-(trifluoromethanesulfonyl)imide (LiTFSI), lithium metaborate (LiBO ₂ ), lithium aluminate (LiAlO ₂ ), lithium triflate (LiCF ₃ SO ₃ ) and lithium chlorosulfonate (LiSO ₃ Cl). The solubility values of these electrolyte conductivity enhancing salts in SO ₂ are from about 10 ² to 10 ⁴ mol/liter (see Table 1). At such low salt concentrations, it can be assumed that in any case, the electrical conductivity values will be low and not sufficient for efficient operation of a rechargeable battery cell.

In order to further improve the possible applications and properties of battery cells containing an SO ₂ based electrolyte, the aim of the present invention is to provide a battery cell with an SO ₂ based electrolyte which, compared to prior art battery cells:

- has a wide electrochemical window, as a result of which there is no oxidative decomposition of the electrolyte on the positive electrode;

- contains a stable coating layer on the negative electrode, while the capacity of this layer is low and during subsequent operation there is no reductive decomposition of the electrolyte on the negative electrode;

- contains an electrolyte based on SO ₂ that has good dissolving power for conductive salts and is therefore a good conductor of ions and an electronic insulator, which facilitates the transfer of ions and minimizes self-discharge;

- contains an SO ₂ based electrolyte which is inert to other battery cell components such as separators, electrode materials and cell packaging materials,

- is resistant to other undue influences, such as electrical, mechanical or thermal;

- contains an electrolyte based on SO ₂ characterized by increased resistance to residual amounts of water in the components of the battery cells;

- has improved electrical performance, in particular, high energy density

- has an improved ability to recharge and deep discharge, as well as less self-discharge and

- characterized by an increased service life, in particular, a large number of charge and discharge cycles.

Such battery cells must, in particular, have very good electrical energy and performance characteristics, high operational reliability and durability, in particular, a large number of useful charge and discharge cycles without electrolyte decomposition during operation of the rechargeable battery cell.

This goal is achieved by a battery cell with features of claim 1 of the claims of the present invention. Claims 2-30 describe preferred embodiments of the battery cell according to the invention.

The battery cell according to the present invention comprises an active metal, at least one positive electrode, at least one negative electrode, a housing and an electrolyte. The negative electrode has an active material selected from the group:

- carbon inclusion material,

alloy forming active material,

- intercalary material without carbon content,

- conversion active material.

The SO ₂ based electrolyte contains at least one first conductive salt. This first conductive salt has the formula (I):

- In formula (I), M means a metal selected from the group consisting of: alkali metals, alkaline earth metals, metals from group 12 of the Periodic Table of the Elements and aluminum, x is an integer from 1 to 3.

- Substituents R ¹ , R ² , R ³ and R ⁴ are independently selected from the group consisting of C ₁ -C ₁₀ alkyl, C ₂ -C ₁₀ alkenyl, C ₂ -C ₁₀ alkynyl, C ₃ -C ₁₀ cycloalkyl, C ₆ - C ₁₄ aryl; and C ₅ -C ₁₄ heteroaryl.

- Z represents aluminum or boron.

By "inclusion material" in the present invention is meant carbon materials having a structure into which active metal ions can enter or leave during operation of a lithium ion battery cell. This means that electrode processes occur not only on the surface of the electrodes, but also inside the structure. If, for example, a salt based on lithium that increases the electrical conductivity of the electrolyte is used, then lithium ions can enter this including material during charging of the battery cell, and can leave it during discharging of this battery.

The alloy-forming active materials are generally metals and metal alloys, as well as their oxides, which form an alloy with the active metal, for example lithium, such alloying occurring in or at the negative electrode and being substantially reversible. In contrast to the containing material, the active metal in alloys does not intrude into an already existing structure. The incorporation of the active metal occurs rather through phase transformation processes, which, for example, when using lithium as the active metal, can lead to a lithium-containing binary end product. When the alloy is formed, expansion of the active material may occur.

The term "intercalary connection" in the present invention should be understood as a subset of the inclusion materials described above. Such an intercalary compound acts as a seed matrix with vacancies connected to each other. Active metal ions can diffuse into these vacancies during the discharge of a rechargeable battery cell and become embedded there. As part of this introduction of active metal ions in the seed matrix, either only minor structural changes occur, or they do not occur at all.

The conversion-active materials undergo during electrode processes a chemical conversion or transformation leading to the reversible formation of a chemical bond between the active metal and the active material. The SO ₂ -based electrolyte used in the battery cell contains SO ₂ not only as an additive at a low concentration, but also at concentrations that ensure the mobility of the ions of the first conductive salt contained in the electrolyte, and ensure the transfer of charges, at least partially , mostly or even completely through SO ₂ . The first conductive salt is dissolved in the latter and has very good solubility in it. Together with gaseous SO ₂ it is able to form a liquid solvate complex in which SO ₂ binds. In this case, the vapor pressure of the liquid solvate complex is noticeably reduced compared to pure SO ₂ , and low vapor pressure electrolytes are formed. However, it is also within the scope of the invention that, in the preparation of the electrolyte according to the invention, depending on the chemical structure of the first conductive salt of the formula (I), a decrease in vapor pressure can occur. In such a case, it is preferable that the preparation of the electrolyte according to the invention is carried out at low temperature or under pressure. The electrolyte may also contain several conductive salts of formula (I), which differ from each other in their chemical structure.

The concept of ''C ₁ -C ₁₀ alkyl'' includes in the present invention linear or branched saturated hydrocarbon groups containing from one to ten carbon atoms. These include in particular methyl, ethyl, n-propyl, isopropyl, n-butyl, sec, butyl, iso-butyl, tert, butyl, n-pentyl, iso-pentyl, 2,2-dimethylpropyl, p-hexyl, iso-hexyl, 2-ethylhexyl, n-heptyl, iso-heptyl, n-octyl, iso-octyl, n-nonyl, n-decyl, etc.

The term ''C ₂ -C ₁₀ alkenyl'' includes, according to the present invention, unsaturated linear or branched hydrocarbon groups containing from two to ten carbon atoms, the hydrocarbon groups having at least one C-C double bond. These include, in particular, ethenyl, 1-propenyl, 2-propenyl, 1-n-butenyl, 2-p-butenyl, iso-butenyl, 1-pentenyl, 1-hexenyl, 1-heptenyl, 1-octenyl, 1- nonenyl, 1-decenyl, etc.

The term "C ₂ -C ₁₀ alkynyl" includes, according to the present invention, unsaturated linear or branched hydrocarbon groups containing from two to ten carbon atoms, the hydrocarbon groups having at least one C-C triple bond. These include, in particular, ethynyl, 1-propynyl, 2-propynyl, 1-n-butynyl, 2-n-butynyl, iso-butynyl, 1-pentynyl, 1-hexynyl, 1-heptynyl, 1-octynyl, 1- noninyl, 1-decynyl, etc.

The term "C ₃ -C ₁₀ cycloalkyl" includes, according to the present invention, cyclic saturated hydrocarbon groups containing from three to ten carbon atoms. These include, in particular, cyclopropyl, cyclobutyl, cyclopentyl, cyclohexyl, cyclohepsil, cyclohexyl, cyclononyl and cyclodecanyl.

The term "C ₆ -C ₁₄ aryl" includes in the present invention aromatic hydrocarbon groups containing from six to fourteen ring carbon atoms. These include, in particular, phenyl (group C ₆ H ₅ ), naphthyl (group C ₁₀ H ₇ ) and anthracyl (group C ₁₄ H ₉ ).

The term "C ₅ -C ₁₄ heteroaryl" includes in the present invention aromatic hydrocarbon groups containing from five to fourteen ring carbon atoms, in which at least one carbon atom is replaced or replaced by a nitrogen, oxygen or sulfur atom. These include, in particular, pyrrolyl, furanyl, thiophenyl, pyrridinyl, pyranyl, thiopyranyl, etc. All the above-mentioned hydrocarbon groups are linked through an oxygen atom to the central atom according to formula (I).

A battery cell with such an electrolyte has an advantage over battery cells containing electrolytes known from the prior art in that the first conductive salt contained therein has improved resistance to oxidation and is therefore substantially immune to degradation at elevated voltages. on the element. This electrolyte is resistant to oxidation preferably at least at an upper potential up to 4.0 V, preferably at least at an upper potential up to 4.4 V, preferably at least at an upper potential up to 4.8 V, preferably at least at an upper potential of up to 5.2 V, preferably at least at an upper potential of up to 5.6 V and particularly preferably at an upper potential of up to 6.0 V. Thus, when using such electrolyte in the battery cell, there is only a slight decomposition or even no decomposition of the electrolyte within the operating potential, i.e. in the range between the charge end voltage and the discharge end voltage, both electrodes of the battery cell. As a result, the battery cells can have a final charge voltage of at least 4.0 V, preferably at least 4.4 V, preferably at least 4.8 V, preferably at least at least 5.2 V, preferably at least 5.6 V, particularly preferably at least 6.0 V.

The service life of a battery cell with such an electrolyte is noticeably longer than that of a battery cell with an electrolyte known from the prior art.

In addition, a battery cell with such an electrolyte is resistant to low temperatures. At a temperature of, for example, -40° C., 61% of the charged capacity can still be discharged. The electrical conductivity of the electrolyte at low temperatures remains sufficient for the operation of the battery cell.

In addition, a battery cell with such an electrolyte has an increased resistance to residual amounts of water. If the electrolyte still contains small residual amounts of water (in the range of a few parts per million), then the electrolyte or the first conductive salt forms with water, in comparison with electrolytes based on SO ₂ known from the prior art, hydrolysis products that are noticeably less aggressive towards to the element's components. As a result, the absence of water in the electrolyte plays a less significant role in comparison with electrolytes based on SO ₂ known from the prior art. These advantages of the electrolyte according to the invention outweigh the disadvantage caused by the fact that the first conductive salt of formula (I) has significantly larger anions compared to the conductive salts known from the prior art. This increased anion size causes, compared to the electrical conductivity of LiAlCl ₄ , a lower electrical conductivity of the first conductive salt of formula (I).

negative electrode.

The advantages of using a battery cell according to the present invention with respect to said negative electrode are described below. According to a first embodiment of the present invention, in the battery cell, the lithium negative electrode contains alloy-forming anode-active materials, in particular silicon. In other words, by acting as an active metal, lithium forms an alloy with the active material that forms the alloy.

According to another embodiment of the present invention, the battery cell provides that the inclusion material is selected from the group consisting of graphite, natural graphite, synthetic graphite, mesocarbon microbeads (MCMB), carbon-coated graphite and amorphous carbon. Graphite insert material as a kind of graphite is preferred. Natural graphite can be flaky (in the form of a so-called coagulation stimulator) or have a rounded shape. Synthetic graphite, also called graphitized carbon or electrographite, can be obtained by graphitizing non-graphitic carbon, chemical vapor deposition of hydrocarbons at temperatures above 2500 K, decomposition of chemically unstable carbides, or crystallization of carbon-rich melts of metals, and can be used due to its uniform structure and increased degree of purity compared to natural graphite and other materials as the anode material. The graphitized mesocarbon microgranules preferably have an almost spherical structure with a diameter of, for example, 1 to 40 urn and hence a small specific surface area. Mesocarbon microgranules belong to the so-called ''soft carbon''. It is also contemplated within the scope of the invention that carbon fibers such as mesophase resin carbon fibers, mesophase pitch carbon fibers (MCF) or vapor phase grown carbon fibers (VGUF) can be used as active materials for the negative electrode. The previously mentioned amorphous carbon does not have a crystalline long-range order. Examples of this are graphitizable (soft carbon) and non-graphitizable carbon (hard carbon).

According to another embodiment of the battery cell according to the invention, it is provided that the alloy-forming active material is selected from the group consisting of lithium storage metals and metal alloys, or from the group consisting of lithium storage metal oxides and metal alloys. This includes mainly silicon (Si), in particular nano-silicon, pm-silicon, silicon nanofibers, germanium (Ge), tin (Sn), SnCo _x C _y , SnSi, etc., as well as their oxides, for example, SnO _x , SiO _x , oxide glasses of Sn and Si, etc. Oxides of the composition MO _x , where M means a metal, such as SiO _x , consist, for example, of a mixture of components SiO, SiO and SiO ₂

In this case, the weight fractions of the individual components may vary. The theoretical capacity of some of these alloy-forming anode active materials (anode active materials) is listed in Table 2

According to another embodiment of the present invention, the battery cell provides that the anode active material forming the alloy is a silicon-based anode active material. This material is characterized by a very high theoretical capacity.

According to another variant of the present invention, it is provided that the anode-active material forming the alloy is made of silicon or silicon oxides or mixtures of silicon and its oxides.

Silicon-based anode active materials can be classified, for example, according to their particle geometry or morphology into 0D, 1D, 2D and 3D materials. 0D silicon materials include, for example, silicon nanoparticles < 150 nm in size, which are able to expand during electrochemical cyclization without causing any damage. 1D nanorods, silicon nanowires, and nanotubes have good conductivity along the 1D transport channel due to the fact that, as a rule, they are directly connected to the electrical circuit in the electrode complex. The group of 2D silicon materials includes, for example, silicon thin films and nanowafers, which generally have high capacitance. It was found that with a decrease in the layer thickness, the reversible capacitance and electrochemical cyclic stability increase. Silicon-based 3D porous structures, as well as mesh structures, are able to withstand volumetric changes due to their porous nature and therefore maintain structural integrity. At the same time, these materials have a high antiknock density and, consequently, a theoretically higher volumetric capacity than smaller nanostructures.

According to another embodiment of the present invention, the lithium-alloyed anode active materials in the battery cell contained lithium in the battery cell prior to use. This so-called lithium pre-treatment reduces capacity losses, for example as a result of the formation of a coating layer in the first cycle.

According to another embodiment of the present invention, it is provided in the battery cell that the negative electrode comprises at least one anode active material forming an alloy, in particular at least one anode active material forming an alloy by means of lithium, in combination, according to with at least one carbon containing material. Combinations of silicon and/or silicon oxides with graphite are preferred. This includes, for example, composites that form mechanically stable complexes. The materials are recessed one into the other. The combination can also be in the form of non-cohesive mixtures, so-called compositions. The combination can include, for example, silicon and graphite or SiO _x and graphite.

According to another embodiment of the present invention, in a battery cell, the negative electrode comprises carbon-free lithium intercalary anode active materials, such as lithium titanates (eg, Li ₄ Ti ₅ O ₁₂ ).

In the case of this preferred embodiment of the present invention, in the battery cell, the anode active material is a conversion active material selected from the group consisting of manganese oxides (MnO _x ), iron oxides (FeO _x ), cobalt oxides (CoO _x ), nickel oxides ( NiO _x ), copper oxides (CuO _x ), or from the group consisting of magnesium hydride ((MgH ₂ ), titanium hydride (TiH ₂ ), aluminum hydride (AlH ₃ ) and tert hydrides based on boron, aluminum, magnesium, and etc.

In the case of another embodiment of the present invention, it is provided in the battery cell that the negative electrode is made porous, while the porosity is preferably not more than 50%, preferably not more than 45%, preferably not more than 40%, preferably not more than 35%, preferably not more than 30 %, preferably not more than 20% and particularly preferably not more than 10%. Porosity is the volume of voids from the total volume of the negative electrode, and the volume of voids is formed by the so-called pores or empty spaces. This porosity provides an increase in the inner surface of the negative electrode. In addition, porosity reduces the density of the negative electrode, and hence its weight.

Separate pores of the negative electrode are filled during operation mainly completely with electrolyte.

According to another embodiment of the battery cell according to the invention, it is provided that the negative electrode has a discharge element. This means that the negative electrode contains, in addition to the active material or the containing material, also a discharge element. This diverting element is designed to provide the necessary electronic conductivity at the point of connection of the active material of the negative electrode. To do this, the discharge element is in contact with the active material involved in the reaction taking place on the negative electrode. Such a diverting element can be made flat in the form of a thin metal sheet or a thin metal foil. The thin metal foil preferably has a perforated or mesh structure. The flat wicking element may also consist of a metal-coated polymer film. The thickness of such metal coatings ranges from 0.1 to 20 µm. The negative electrode active material is preferably deposited on the surface of a thin metal sheet, a thin metal foil or a metal-coated polymer film. The active material may be applied to the front and/or back side of the planar wicking element. Such flat outlet elements have a thickness in the range of 5 to 50 µm. The thickness of the flat outlet element is preferably in the range of 10 to 30 µm. When flat discharge elements are 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. The surface specific capacitance of the negative electrode, referred to the coating on one side, is preferably at least 0.5 mAh/cm ² when using a flat discharge element, with the following values being preferred in this sequence: 1 mAh/cm ² , 3 mAh/cm ² , 5 mAh/cm ² , 10 mAh/cm ² , 15 mAh/cm ² , 20 mAh/cm ² .

In addition, there is the possibility that the wicking element can be made three-dimensional in the form of a porous metal structure, in particular in the form of metal foam. The term "three-dimensional porous metal structure" here means any structure consisting of metal, located not only like a thin metal sheet or metal foil along the length and width of a flat electrode, but also along its thickness. The three-dimensional porous metal structure is so porous that the negative electrode active material can penetrate into the pores of the metal structure. The charge of the negative electrode is determined by the amount of active material that has penetrated or deposited. If the discharge element is made three-dimensional in the form of a porous metal structure, in particular in the form of a metal foam, then the thickness of the negative electrode will be preferably at least 0.2 mm, preferably at least 0.3 mm, preferably at least at least 0.4 mm, preferably at least 0.5 mm, particularly preferably at least 0.6 mm. In this case, the thickness of the electrodes is noticeably larger compared to the negative electrodes used in organic lithium-ion battery cells. According to another advantageous embodiment, it is provided that the surface specific capacity of the negative electrode, when using a three-dimensional wicking element, in particular in the form of a metal foam, is preferably at least 2.5 mAh/cm ² , the following values being preferred 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 . If the discharge element is made three-dimensional in the form of a porous metal structure, in particular in the form of a metal foam, then the amount of active material of the negative electrode, i.e. the charge of the electrode, in relation to its surface, is at least 10 mg/cm ² , preferably at least 20 mg/cm ² , preferably at least 40 mg/cm ² , preferably at least , 60 mg/cm ² , preferably at least 80 mg/cm ² , particularly preferably at least 100 mg/cm ² . Such a negative electrode charge has a positive effect on the process of charging and discharging a rechargeable battery cell.

According to another embodiment of the battery cell according to the invention, the negative electrode contains at least one binder. This binder is preferably a fluorinated binder, in particular polyvinylidene fluoride and/or a terpolymer consisting of tetrafluoroethylene, hexafluoropropylene and vinylidene fluoride. However, a binder is also possible, consisting of a single polymer formed by monomeric structural units of a conjugated carboxylic acid, or an alkali metal salt, an alkaline earth metal salt, or an ammonium salt of a conjugated carboxylic acid, or combinations thereof. Also, the binder may consist of a polymer based on monomer units of styrene and butadiene. In addition, the binder may come from the group of carboxymethyl celluloses.

The binder is present in the negative electrode mainly at a content of not more than 20 wt. %, preferably not more than 15 wt. %, preferably not more than 10 wt. %, preferably not more than 7 wt. %, preferably not more than 5 wt. %, particularly preferably not more than 2 wt. %, based on the total weight of the negative electrode.

According to a preferred embodiment, in the battery cell of the invention, the negative electrode contains at least one electrically conductive additive. The electrically conductive additive should preferably have a low weight, a high chemical resistance and a large specific surface area. Examples of electrically conductive additives are special carbon (carbon black, Super P, acetylene black), carbon fibers (carbon nanotubes, carbon nanofibers), fine graphites and graphene (nanosheets),

Electrolyte

Advantageous battery cell improvements with respect to SO ₂ based electrolyte are described below.

According to one embodiment of the battery cell, the substituents R ¹ , R ² , R ³ , R ^{4 of} the first electrolyte conductivity increasing salt are independently selected from the group consisting of:

- C ₁ -C ₆ alkyl; preferably C ₂ -C ₄ alkyl; more preferably alkyl groups 2-propyl, methyl and ethyl;

- C ₂ -C ₆ alkenyl; preferably C ₂ -C ₄ alkenyl; more preferably ethenyl and propenyl alkenyl groups;

- C ₂ -C ₆ alkynyl; preferably C ₂ -C ₄ alkynyl;

- C ₃ -C ₆ cycloalkyl;

- phenyl; and C ₅ -C ₇ heteroaryl.

In the case of this preferred embodiment of the electrolyte based on SO ₂ , the term "C ₁ -C ₆ alkyl" includes linear or branched saturated hydrocarbon groups containing from one to six carbon atoms, in particular methyl, ethyl, n-propyl, isopropyl , n-butyl, sec-butyl, isobutyl, tert-butyl, n-pentyl, isopentyl, 2,2-dimethylpropyl, n-hexyl and isohexyl. C ₂ -C ₄ alkyls are preferred among these groups. C ₂ -C ₄ alkyls 2-propyl, methyl and ethyl are most preferred.

In the case of this preferred embodiment of the SO ₂ electrolyte, the term "C ₂ -C ₆ alkenyl" includes unsaturated linear or branched hydrocarbon groups containing from two to six carbon atoms, said hydrocarbon groups having at least one double S-S connection. They include in particular ethenyl, 1-propenyl, 2-propenyl, 1-n-butenyl, 2-n-butenyl, isobutenyl, 1-pentenyl and 1-hexenyl, with C ₂ -C ₄ alkenyls being preferred. Ethenyl and 1-propenyl are most preferred.

In the case of this preferred embodiment of the SO ₂ electrolyte, the term "C ₂ -C ₆ alkynyl" includes unsaturated linear or branched hydrocarbon groups containing from two to six carbon atoms, said hydrocarbon groups having at least one triple S-S connection. They include in particular ethynyl, 1-propynyl, 2-propynyl, 1-n-butynyl, 2-n-6utynyl, isobutynyl, 1-pentynyl and 1-hexynyl. Preferred among them are C ₂ -C ₄ alkynyls.

In the case of this preferred embodiment of the SO ₂ electrolyte, the term "C ₃ -C ₆ cyclic o alkyl" includes cyclic saturated hydrocarbon groups containing from three to six carbon atoms. They include in particular cyclopropyl, cyclobutyl, cyclopentyl and cyclohexyl.

In the case of this preferred embodiment of the SO ₂ based electrolyte, the term ''C ₅ -C ₇ hetero o aryl'' includes phenyl and naphthyl.

In order to increase the solubility of the first conductive salt, in the SO ₂ electrolyte, the substituents R ¹ , R ² , R ³ , R ⁴ are substituted in another embodiment of the battery cell with at least one fluorine atom and/or at least , one chemical group, and this group is selected from the group consisting of C ₁ -C ₄ alkyl, C ₂ -C ₄ alkenyl a, C ₂ -C ₄ alkynyl, phenyl, and benzyl. The chemical groups C ₂ -C ₄ alkyl, C ₂ -C ₄ alkenyl, C ₂ -C ₄ alkynyl, phenyl, and benzyl have the same properties or chemical structures as the previously described hydrocarbon groups. In this regard, the term "substituted" means that individual atoms or groups of atoms of the substituents R ¹ , R ² , R ³ , R ⁴ are replaced by a fluorine atom and/or a specified chemical group.

Particularly high solubility of the first conductive salt in the SO ₂ -based electrolyte can be achieved by having at least one of the R ¹ , R ² , R ³ , R ⁴ substituents a CF ₃ group or an OSO ₂ CF ₃ group.

In a further preferred embodiment of the battery cell, the first conductive salt is selected from the group consisting of:

In order to bring the electrical conductivity and/or other properties of the electrolyte in line with the desired indicator, the electrolyte contains, according to a preferred embodiment of the battery cell according to the invention, at least one second conductive salt and different from the first conductive salt of formula (I). This means that the electrolyte can contain, in addition to the first conductive salt, also the second or second conductive salts, which differ in their chemical composition and chemical structure from the first conductive salt.

In a further preferred embodiment of the battery cell 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 aluminate, halide, oxalate, borate, phosphate, arsenate and gallate. Preferably, the second conductive salt is lithium tetrahaloaluminate, in particular LiAlCl ₄ .

In addition, according to another embodiment of the battery cell according to the invention, at least one additive is contained in the electrolyte. This 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 (bis-oxylate)borate, lithium difluoro(oxalate)borate, lithium tetrafluoro(oxalate)phosphate, lithium oxalate, 2 -vinylpyridine, 4-vinylpyridine, cyclic exomethylene carbonates, sultones, cyclic and acyclic sulfonates, acyclic sulfites, cyclic and acyclic sulfinates, organic esters of inorganic acids, acyclic and cyclic alkanes, which (acyclic and cyclic alkanes) have a boiling point at a pressure of 1 atm at least 36°C, 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, halogenation halogenated cyclic and acyclic silylamines, halogenated cyclic and acyclic esters, halogenated cyclic and acyclic amides, halogenated cyclic and acyclic anhydrides and halogenated organic heterocycles.

In another preferred embodiment of the battery cell, the electrolyte has the following composition in relation to the total weight of the electrolyte:

(i) 5 to 99.4 wt. % sulfur dioxide,

(ii) from 0.6 to 95 wt. % of said first conductive salt,

(iii) 0 to 25 wt. % of said second conductive salt and

(iv) 0 to 10 wt. % additive.

As mentioned above, the electrolyte may contain not only one first conductive salt of formula (1) and one second conductive salt, but also several first conductive salts of formula (1) and several second conductive salts. The percentages given above also include, in the latter case, a few first and a few second conductive salts. The concentration of the first conductive salt is 0.01 to 10 mol/l, preferably 0.05 to 10 mol/l, preferably 0.1 to 6 mol/l, particularly preferably 0.2 to 3.5 mol/l , from the total electrolyte volume.

Another advantageous development of the battery cell according to the invention provides that the electrolyte contains at least 0.1 mol SO ₂ , preferably at least 1 mol SO ₂ , preferably at least 5 mol SO ₂ , preferably at least 10 mol SO ₂ , particularly preferably at least 20 mol SO ₂ per 1 mol of conductive salt. The electrolyte may also contain very high mole fractions of SO ₂ , with a preferred upper limit being 2600 mol per mol of conductive salt, with the upper limits being preferred in this order: 1500, 1000, 500 and 100 mol SO ₂ per 1 mol of conductive salt . The term "per 1 mol of conductive salt" refers here to all conductive salts contained in the electrolyte. Electrolytes based on SO ₂ with this concentration ratio between SO ₂ and conductive salt have the advantage that they can dissolve a larger amount of conductive salt compared to electrolytes known from the prior art, which are based, for example, on a mixture of organic solvents.

According to the present invention, it has surprisingly been found that an electrolyte with a relatively low concentration of conductive salt, despite the associated increased vapor pressure, is preferred, in particular due to its durability over many charging and discharging cycles of the battery cell. The concentration of SO ₂ in the electrolyte affects its electrical conductivity. Therefore, by selecting the SO ₂ concentration, it is possible to match the electrical conductivity of the electrolyte with the planned use of a battery cell with such an electrolyte.

The total content of SO3 and the first conductive salt may be more than 50 wt. % by weight of the electrolyte, preferably more than 60 wt. %, preferably more than 70 wt. %, preferably more than 80 wt. %, preferably more than 85 wt. %, preferably more than 90 wt. %, preferably more than 95 wt. %, preferably more than 99 wt. %. The electrolyte may contain at least 5 wt. % SO ₂ of the total electrolyte contained in the battery cell, with 20 wt. %, 40 wt. %. and 60 wt. %SO2 _. The electrolyte may also contain up to 95 wt. % SO ₂ , and in this series the maximum values of 80 wt. % and 90 wt. %SO2 _.

Within the scope of the invention, it is provided that the electrolyte preferably contains only a small percentage of at least one organic solvent or is not present at all. Preferably, the proportion of the organic solvent in the electrolyte, present, for example, in the form of a single solvent or a mixture of several solvents, may not exceed 50 wt. % by weight of the electrolyte. Particularly preferred are smaller proportions of not more than 40 wt. %, not more than 30 wt. %, not more than 20 wt. %, not more than 15 wt. %, not more than 10 wt. %, not more than 5 wt. % or not more than 1 wt. % by weight of the electrolyte. An electrolyte free of organic solvents is also preferred. Due to the presence of only a small proportion of organic solvents, or even their complete absence, the electrolyte is either slightly flammable or not flammable at all. This improves the operational reliability of a rechargeable battery cell using such an SO ₂ -based electrolyte. Particularly preferred is an SO ₂ based electrolyte containing substantially no organic solvents.

According to an advantageous embodiment of the present invention, the battery cell electrolyte, based on its total weight, has the following composition:

(i) 5 - 99.4 wt. % sulfur dioxide,

(ii) 0.6 - 95 wt. % first conductive salt,

(iii) 0 - 25 wt. % second conductive salt,

(iv) 0-10 wt. % additive,

(v) 0 - 50 wt. % organic solvent.

active metal.

The following is a description of preferred embodiments of the battery cell according to the invention with respect to the active metal.

According to the first preferred embodiment, in the battery cell, the active metal is:

- an alkali metal, in particular lithium or sodium,

- an alkaline earth metal, in particular calcium,

- a metal from group 12 of the Periodic Table of the Elements, in particular zinc,

- aluminum.

positive electrode.

The preferred embodiments of the battery cell according to the invention with respect to the positive electrode are described below.

According to a first advantageous embodiment of the present invention, it is provided in the battery cell that the positive electrode can be charged to at least an upper potential of 4.0 V, preferably 4.4 V, preferably at least 4.8 V, preferably at least 5.2 V, preferably at least 5.6 V, particularly preferably at least 6.0 V.

According to another embodiment of the battery cell according to the invention, the positive electrode contains at least one active material. This material can accumulate active metal ions, give off and reabsorb active metal ions during the operation of the battery cell.

According to an advantageous embodiment of the present invention, in a battery cell, the positive electrode comprises at least one intercalary compound. The term ''intercalary compound'' refers to the present invention a subgroup of the above described insert materials. This intercalary compound acts as the main matrix with vacancies linked to each other. Active metal ions can diffuse into these vacancies during the discharge of the battery cell and be stored there. With such an incorporation of active metal ions, only insignificant structural changes occur in the main matrix or they do not occur at all.

According to a preferred embodiment of the battery cell according to the invention, the positive electrode contains at least one convertible compound. The term ''transformable compound'' is to be understood in the sense of the present invention as materials which, during electrochemical activity, form other materials, i.e. During the charging and discharging of a battery cell, chemical bonds are broken and new ones are formed. During absorption or release of active metal ions, structural changes occur in the matrix of the convertible compound.

According to a preferred development in the battery cell according to the invention, the active material has the composition: A _x M' _y M''zO _a . In this composition, A _x M' _y M'' _z O _a means:

- A - at least one metal selected from the group consisting of alkali metals, alkaline earth metals, metals of group 12 of the Periodic Table of the Elements or aluminum,

- M' at least one metal selected from the group consisting of the elements: Ti, V, Mn, Fe, Co, Ni, Cu, Zn,

- M'' - at least one element selected from the group consisting of elements of groups 2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13, 14, 15 and 16 of the Periodic element systems,

- x, y - independently of each other, numbers greater than 0,

- z is a number greater than or equal to 0,

- a - a number greater than 0,

- A - preferably lithium, ie. the compound may have the composition: Li _x M'yM'' _z O _a . In this case, the indices y, z in the composition A _x M' _y M'' _z O _a refer to the totality of metals and elements, which are represented through M', M'', respectively. If, for example, M' refers to two metals M' ¹ and M' ² , then it is valid for index y: y=y1+y2, where y1 and y2 mean metals M' ¹ and M' ² Indices x, y, z , and must be chosen in such a way that charge neutrality is maintained within the composition. Examples of compounds in which M' means two metals are oxides of lithium-nickel-manganese-cobalt in the composition of Li _x Ni _y1 Mn _y2 Co _z O ₂ with M' ¹⁼ Ni, M' ² =Mn and M''= Co.

Examples for compounds in which z=0, i.e. there is no additional metal or element M'', are oxides of lithium-cobalt Li _x Co _y O _a .. If, for example, M'' means two elements, of which one is metal M'' ¹ and the other element is phosphorus as M'' ² , then for index z it will be valid: z: z=z1+z2, while z1, z2 mean metal M'' ¹ and phosphorus (M'' ² ). The indices x, y, z, and must be chosen so that charge neutrality is ensured within the composition.

Examples for compounds in which z=0, i.e. there is no additional metal or element M'', are oxides of lithium-cobalt Li _x Co _y O _a .. If, for example, M'' means two elements, of which one is metal M'' ¹ and the other element is phosphorus as M'' ² , then for index z it will be valid: z: z=z1+z2, while z1, z2 mean metal M'' ¹ and phosphorus (M'' ² ), indices of metal M'' ¹ and phosphorus (M '' ² ). The indices x, y, z, and must be chosen so that charge neutrality is ensured within the composition.

Examples of compounds in which they mean: A - lithium, M '' - metal M - and phosphorus, then M '' ² are lithium-iron-manganese phosphates Li _x Fe _y Mn _z1 P _z2 O ₄ at A \u003d Li, M ' =Fe, M'' ¹ =Mn and M'' ² =P and z2=1.

In another composition, M'' can mean two non-metals, for example, fluorine as M'' ¹ and sulfur as M'' ² . Examples of such compounds are lithium-iron-fluorine sulfates Li _x Fe _y F _z1 S _z2 O ₄ where A is Li, M' is iron, M'' ¹ is fluorine and M'' ² is phosphorus.

According to a preferred development of the battery cell according to the invention, it is provided that M' means the metals nickel and manganese, M'' means cobalt.

In this case, we can talk about compositions of the formula Li _x Ni _y1 Mn _y2 Co _z O ₂ (NMC), i.e. about oxides of lithium-nickel-manganese-cobalt having the structure of layered oxides. Examples of such lithium-nickel-manganese-cobalt oxide active materials are LiNi _1/3 Mn _1/3 Co _1/3 O ₂ (NMC111), LiNi _0.6 Mn _0.2 Co _0.2 O ₂ (NMC622) and LiNi _0.8 Mn _0.1 Co _0.1 O ₂ (NMC811). Other lithium-nickel-manganese-cobalt oxide compounds may contain the compositions: LiNi _0.5 Mn _0.3 Co _0.2 O ₂ , LiNi _0.5 Mn _{0.25Co 0.25} O ₂ , LiNi _0.52 Mn _0.32 Co _0.16 O ₂ , LiNi _0.55 Mno.30Co _0.15 O ₂ , LiNi _0.58 Mn _0.14 Co _0.28 O ₂ , LiNi _0.64 Mn _0.18 Co _0.18 O ₂ , LiNi _0.65 Mn _0.27 Co _0.08 O ₂ , _{LiNi 0.7} Mn _0.2 Co _0.1 O ₂ , _{LiNi 0.7} Mn _0.15 Co _0.15 Co 0.15 _0.10 Co _0.18 O ₂ , LiNi _0.76 Mn 0.76 Mn _0.14 Co _0.10 O ₂ , LiNi _0.86 Mn _0.04 Co _0.10 O ₂ , LiNi _0.90 Mn _0.05 Co _0.05 O ₂ , LiNi _0.95 Mn _0.025 Co _0.025 O ₂ or their combination. By means of these connections, positive electrodes can be produced for battery cells with cell voltages above 4.6 V. According to another preferred development of the battery cell according to the invention, it is provided that the active material is a metal oxide with a high content of lithium and manganese. This metal oxide may contain the composition Li _x Mn _y M'' _z O _a . Therefore, M' means in the above formula Li _x M' _y M'' _z O _a manganese (Mn).

Here index x is greater than or equal to 1, index y is greater than index z or the sum z1+z2+z3, etc. If, for example, M ^{'' includes} two metals M''1 and M''2 with indices z1 and z2 (for example, Li _1.2 Mn _0.525 Ni _0.175 Co _0.1 O ₂ , where: M'' ¹⁼ Niz1=0.175 and M'' ² =Co z2=0.1), then for the index it will actually decrease: y>z1+z2 . The index z is greater than or equal to 0, the index a is greater than 0. The indices x, y and z, a should be chosen in such a way that charge neutrality is ensured within the composition. Metal oxides with a high content of lithium and manganese can also be described by the formula mLi ₂ MnO3⋅(1-m)LiM'O ₂ , where: 0<m<1. Examples of such compounds are Li _1.2 Mn _0.525 Ni _0.175 Co _0.1 O ₂ , Li _1.2 Mn _0.6 Ni _0.2 O ₂ or Li _1.2 Ni _0.13 Co _0.13 Mn _0.54 O ₂ ..

According to another preferred development, the battery cell according to the invention provides that the composition corresponds to the formula A _x M' _y M'' _z O ₄ . These compounds have a spinel type structure. For example, there may be: A - lithium, M' - cobalt and M'' - manganese. In this case, in relation to the active material, we are talking about the oxide of lithium-cobalt-manganese (LiCoMnO ₄ ). LiCoMnO ₄ can be used to produce positive electrodes for battery cells with cell voltages above 4.6 V. This LiCoMnO ₄ preferably lacks Mn ³⁺ . In another example, M' may be nickel and manganese. In this case, the active material is lithium-nickel-manganese oxide (LiNiMnO ₄ ). The molar fractions of both metals M' and M'' may vary. Lithium-nickel-manganese oxide may, for example, have the composition LiNi _0.5 Mn _1.5 O ₄ .

According to a preferred embodiment of the battery cell, as active material, the positive electrode contains at least one active material which is a convertible compound. During absorption of an active metal, such as lithium or sodium, the convertible compounds undergo a solid phase redox reaction during which the crystal structure of the material changes. This occurs when chemical bonds break and recombine. Completely reversible reactions of convertible compounds can be written, for example, as follows:

Examples of conversion compounds: FeF ₂ , FeF ₃ , CoF ₂ , CuF ₂ , NiF ₂ , BiF ₃ , FeCl ₃ , FeCl ₂ , CoCl ₂ , NiCl ₂ , CuCl ₂ , AgCl, LiCl, S, Li ₂ S, Se, Li ₂ Se, Te, I and LiI.

In a preferred embodiment, the compound has the composition: A _x M' _y M'' _z1 M'' _z2 O ₄ where: M'' is phosphorus and z2 is 1. A compound having the composition Li _x M' _y M'' _z1 M'' _Z2 O ₄ are the so-called lithium metal phosphates. In particular, this compound has the composition Li _x Fe _y Mn _z1 P _z2 O ₄ . Examples of lithium metal phosphates are lithium iron phosphate (LiFePO ₄ )) or lithium iron manganese phosphates (Li(Fe _y Mn _z )PO ₄ ). An example of lithium-iron-manganese phosphate is a phosphate having the composition Li(Fe _0.3 Mn _0.7 )PO ₄ . An example of lithium-iron-manganese phosphate is a phosphate having the composition Li(Fe _0.3 Mn _0.7 )PO ₄ . Lithium metal phosphates with other compositions can also be used in the battery cell according to the invention.

According to a preferred embodiment of the battery cell according to the invention, it is provided that the positive electrode contains at least one metal compound. This metal compound is selected from the group consisting of a metal oxide, a metal halide or a metal phosphate. Preferably the metal of this compound is a transition metal with an atomic number of 22 to 28 of the Periodic Table of the Elements, in particular cobalt, nickel or iron. According to another preferred development of the battery cell according to the invention, it is provided that the positive electrode contains at least one metal compound having the chemical structure of a spinel, a layered oxide, a convertible compound or a polyanionic compound. The invention also provides that the positive electrode contains as an active material at least one of the described compounds or a combination thereof. By compound combination is meant a positive electrode containing at least two of the described materials. According to a preferred embodiment of the battery cell according to the invention, it is provided that the positive electrode comprises a discharge element. This means that, in addition to the active material, a diverting element is also provided in the positive electrode. This diverting element is designed to be able to provide the necessary electrically conductive connection of the active material as a positive electrode. To do this, the diverting element is in contact with the active material involved in the electrode reaction of the positive electrode. This outlet element is made flat in the form of a thin metal sheet or thin metal foil. Preferably, the thin metal foil has a perforated or mesh structure. The flat wicking element can also consist of a metal-coated plastic film. Such metallic coatings have a thickness in the range of 0.1 to 20 µm. The positive electrode active material is preferably deposited on the surface of a thin metal sheet, a thin metal foil or a metal-coated polymer film. The application of the active material can be carried out on the front and/or back side of the flat wicking element. Such flat outlet elements have a thickness in the range of 5 to 50 µm. The thickness of the flat outlet element is preferably from 10 to 30 µm. When flat discharge elements are used, the total thickness of the positive 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. The surface-specific capacitance of the positive electrode, referred to the coating on one side, is preferably at least 0.5 mAh/cm ² when using a flat discharge element, with the following values being preferred 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 .

In addition, it is possible to make the positive electrode outlet element three-dimensional in the form of a porous metal structure, in particular in the form of metal foam. The three-dimensional porous metal structure is so porous that the positive electrode active material penetrates into the pores of the metal structure. The amount of active material incorporated or deposited determines the charge on the positive electrode. If the diverting element is made three-dimensional in the form of a porous metal structure, in particular in the form of a metal foam, then in this case the thickness of the positive electrode will preferably be at least 0.2 mm, preferably at least 0.3 mm, preferably , at least 0.4 mm, preferably at least 0.5 mm, particularly preferably at least 0.6 mm. Another preferred embodiment provides that the surface specific capacity of the positive electrode when using a three-dimensional diverting element, in particular in the form of a metal foam, is preferably at least 2.5 mAh/cm ² , while in this order the following are preferred indicators: 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 . If the discharge element is three-dimensional in the form of a porous metal structure, in particular in the form of a metal foam, then the amount of active material in the positive electrode, i.e. the charge of the electrode, in relation to its surface, is at least 10 mg/cm ² , preferably 20 mg/cm ² , preferably at least 40 mg/cm ² , preferably at least 60 mg/cm ² , preferably at least 80 mg/cm ² , particularly preferably at least 100 mg/cm ² . Such a positive electrode charge favorably affects the charging process and the discharging process of the battery cell. According to another preferred development of the battery cell according to the invention, the positive electrode has at least one binder. This binder is preferably a fluorinated binder, in particular polyvinylidene fluoride and/or a terpolymer consisting of tetrafluoroethylene, hexafluoropropylene and vinylidene fluoride. It may also be a binder which consists of a polymer derived from monomeric structural units of a conjugated carboxylic acid or from an alkali metal, alkaline earth metal or ammonium salt of this conjugated carboxylic acid, or a combination thereof. Also, the binder may consist of a polymer based on monomeric structural units of styrene and butadiene. In addition, the binder may come from the group of carboxymethyl celluloses. The binder is present in the positive electrode, preferably in an amount of not more than 20 wt. %, preferably not more than 10 wt. %, preferably not more than 7 wt. %, preferably not more than 5 wt. %, particularly preferably not more than 2 wt. % of the total weight of the positive electrode.

The structure of the battery cell.

The advantageous improvements of the battery cell according to the present invention are described below with respect to its structure:

In order to further improve the function of the battery cell, according to the present invention, the battery cell includes a plurality of negative electrodes and a plurality of positive electrodes which are alternately stacked in a housing. Here, each positive electrode and negative electrode are electrically separated from each other by separators.

The separator may be made of a nonwoven material, a membrane, a woven material, a knitted material, an organic material, an inorganic material, or a combination thereof. Organic separators can be made of unsubstituted polyolefins (eg polypropylene or polyethylene), partially or fully halogenated polyolefins (eg partially or fully fluorinated, in particular PVDF, ETFE, PTFE), ester polymers, polyamide or polysulfones. Separators which include a combination of organic and inorganic materials are, for example, glass fiber textile materials in which the glass fiber is provided with a suitable polymer coating. Said coating preferably contains a fluorine-containing polymer such as polytetrafluoroethylene (PTFE), ethylenetetrafluoroethylene (ETFE), perfluoroethylene propylene (FEP), THF (a ternary polymer of tetrafluoroethylene, hexafluoroethylene and vinylidene fluoride), perfluoroalcopolymer (PFA), aminosilane, polypropylene or polyethylene (PE) . The separator can also be folded into the battery cell housing, for example in a so-called "Z-fold". In this Z-fold, the strip separator is folded in a Z-fold through or around the electrodes. Moreover, the separator can also be in the form of release paper.

Within the scope of the invention, the separator can be made in the form of a sheath, with each positive electrode and each negative electrode surrounded by a sheath. The shell may consist of a nonwoven material, a membrane, a fabric, a knitted fabric, an organic material, an inorganic material, or combinations thereof.

The positive electrode sheath ensures uniform movement and distribution of ions in the battery cell. The more uniform the distribution of ions, in particular in the negative electrode, the greater the possibility of charging the negative electrode with the active material and hence the useful capacity of the battery cell. At the same time, the risks that may be associated with uneven charging and the resulting separation of the active metal are eliminated. These advantages are achieved primarily when the positive electrodes of the battery cell are covered by a sheath.

The dimensions of the surface of the electrodes and the shell can be coordinated with each other in such a way that the outer dimensions of the shell and the outer dimensions of the uncovered electrodes coincide in at least one dimension.

The surface area of the sheath may preferably be larger than the surface area of the electrode. In this case, the shell extends beyond the electrode. Therefore, both covering the electrode on both sides of the sheath layer can be connected to each other at the edge of the positive electrode by an edge bond.

According to another preferred embodiment of the battery cell, the negative electrodes are sheathed, while the positive electrodes are not sheathed.

Additional useful features of the present invention are described and explained in more detail below with reference to the drawings, examples and experiments.

fig. 1 shows a first embodiment of a battery cell according to the invention in cross section;

fig. 2 shows an electron microscope image of a three-dimensional porous structure of a metal foam according to the first embodiment of FIG. 1 as a detailed illustration;

fig. 3 shows a second embodiment of a battery cell according to the invention in cross section;

fig. 4 shows a detail of the second embodiment of FIG. 3;

fig. 5 is an exploded view of a third embodiment of a battery cell according to the invention;

fig. 6 shows the potential (in Volts) of four test whole battery cells during charging of negative electrodes containing graphite 1, graphite 2, graphite 3 and graphite 4 as active material as a function of capacitance when a coating layer is formed on the negative electrode;

fig. 7 shows the discharge capacity as a function of the number of cycles of three test whole battery cells containing graphite 1, graphite 2 and graphite 3 as the negative electrode active material;

8 shows the potential (in Volts) of two test solid battery cells when charging negative electrodes containing graphite 1 as the active electrode material as a function of capacitance during the formation of a coating layer on the negative electrode, while the control test solid battery cell is filled control electrolyte, the tested solid battery cell is filled with electrolyte 1;

fig. 9 shows the discharge capacity as a function of the number of cycles of two test whole battery cells containing graphite 1 as the negative electrode active material, while the control test solid battery cell is filled with test electrolyte, the test test battery solid cell is filled with electrolyte 1;

fig. 10 shows the potential (in Volts) of three half-cells when charging negative electrodes containing graphite 2, graphite 3, and graphite 4 as active electrode material as a function of capacitance during the formation of a coating layer on the negative electrode, while the half-cells are filled with a control electrolyte;

fig. 11 shows the potential (in Volts) of two test whole battery cells when charging negative electrodes containing graphite 1 as active electrode material as a function of capacitance during the formation of a coating layer on the negative electrode, with one test whole battery cell filled with electrolyte. 3, the other whole battery cell under test is filled with electrolyte 4;

fig. 12 shows the potential (in Volts) on discharge as a function of the percent charge of three test whole battery cells containing graphite 1 as the negative electrode active material and filled with electrolytes 1, 3 and 4;

fig. 13 shows the potential (in Volts) of three test whole battery cells when charging negative electrodes containing mixtures of SiO _x 5.0%/graphite 3, SiO _x 17.3%/graphite 3 and SiO _x 24.0%/graphite 3 as active electrode materials, as a function of capacitance during formation of the coating layer on the negative electrode;

fig. 14 shows the discharge capacity during the first ten cycles as a function of the number of cycles of three tested whole battery cells containing mixtures of: SiO _x 5.0% / graphite 3, SiO _x 17.3% / graphite 3 and SiO _x 24.0% / graphite 3 as the active material of the negative electrode;

15 shows the potential (in Volts) of four test whole battery cells when charging negative electrodes containing a mixture of nano-silicon (5 wt.%) and graphite 3 (95 wt.%), a mixture of nano-silicon (2, 5 wt.%) and graphite 1 (97.5 wt.%), a mixture of nano-silicon (5.0 wt.%) and graphite 1 (95.0 wt.%) and a mixture of nano-silicon (10 wt. .% and graphite 1 (90 wt.%) as active electrode materials as a function of capacitance during the formation of the coating layer on the negative electrode;

fig. 16 shows the discharge capacity for the first ten cycles as a function of the number of cycles of four tested whole battery cells containing a mixture of nano silicon (5 wt.%) and graphite 3 (95 wt.%), a mixture of nano silicon (2, 5 wt.%) and graphite 1 (97.5 wt.%), a mixture of nano-silicon (5.0 wt.%) and graphite 1 (95.0 wt.%) and a mixture of nano-silicon (10 wt. %) and graphite 1 (90 wt %) as the active material of the negative electrode;

fig. 17 - electrical conductivity (in mS/cm) of electrolyte 1 depending on its concentration;

fig. 18 - electrical conductivity (in C/cm) of electrolyte 3 depending on its concentration;

fig. 19 electrical conductivity (in C/cm) of electrolyte 4 depending on its concentration.

1 shows a first example of a battery cell 2 according to the invention in cross section. Battery element 2 is made in the form of a prismatic element and includes, among other things, a housing 1. This housing 1 covers the electrode device 3, consisting of three positive electrodes 4 and four negative electrodes 5. Positive 4 and negative 5 electrodes are located in the electrode device 3 in the form interleaved stack. However, the housing 1 can accommodate more positive electrodes 4 and/or negative electrodes 5. In general, it is preferable that the number of negative electrodes 5 be one more than the number of positive electrodes 4. This is due to the fact that the outer end surfaces of the electrode stack are formed by the surfaces of the negative electrodes 5. The electrodes 4, 5 are connected through their terminals 6, 7 to the corresponding connecting contacts 9, 10 of the battery cell 2. The cell 2 is filled with an electrolyte based on SO ₂ in such a way that the electrolyte penetrates as completely as possible into all pores or voids, in particular into the electrodes 4, 5. The electrolyte is not shown in FIG. In this exemplary embodiment, the positive electrodes 4 contain an intercalary compound as an active material. By intercalary compound we mean LioMnO ₄ . In this embodiment, the electrodes 4, 5 are made flat, i.e. in the form of layers with a thickness insignificant in relation to their surface extent. Accordingly, they are separated from each other by means of separators 11. The body 1 of the cell 2 of the storage battery is made essentially rectangular in shape, and the electrodes 4, 5 and the walls of the body 1 shown in the section are located perpendicular to the plane of the drawing and are made essentially straight and even. However, the cell 2 of the battery can also be made twisted, in which the electrodes consist of thin layers wound together with a spacer material. The separators 11, firstly, separate the positive 4 and negative 5 electrodes spatially and electrically and, secondly, are permeable, among other things, to active metal ions. In this way, large electrochemically active surfaces are created, which provide a correspondingly large current output.

In addition, the electrodes 4, 5 have a diverting element designed to provide an electronically conductive connection of the active material of the respective electrode. This diverting element is in contact with the active material involved in the reaction at the corresponding electrode 4, 5 (not shown in figure 1). The discharge element is made in the form of a porous metal foam 18. The metal foam 18 is located along the thickness of the electrodes 4, 5. The active material of the positive electrodes 4 and negative electrodes 5 penetrates into the pores of this metal foam 18, evenly filling its pores throughout the entire thickness of the metal structure. To increase the mechanical strength, the positive electrodes 4 contain a binder. By this binder is meant a fluoropolymer. The negative electrodes 5 contain, as an active material, carbon suitable for absorbing lithium ions as a containing material. The structure of the negative electrode 5 is similar to the structure of the positive electrode 4.

FIG. 2 shows an electron microscope image of the three-dimensional porous structure of the metal foam 18 of the first embodiment in FIG. With this scale, it can be determined that the pore diameter (P) is on average over 100 µm, i.e. is relatively large. This metal foam refers to nickel metal foam.

Figure 3 shows a second embodiment of the cell 20 of the battery according to the invention in cross section. This second embodiment differs from the first embodiment in FIG. 1 in that the electrode arrangement comprises one positive electrode 23 and two negative electrodes 22.

Accordingly, they are separated from each other by separators 21 and closed by a housing 28. The positive electrode 23 contains a discharge element 26 in the form of a flat metal foil, on which the active material 24 of the positive electrode 23 is deposited on both sides. foil on which the active material 26 of the negative electrode 22 is deposited on both sides. electrodes closing the electrode stack can only have one-sided coating with active material. The uncovered side faces the wall of the housing 28. The electrodes 22, 23 are connected through their terminals 29, 30 to the corresponding connecting contacts 31, 32 of the battery cell 20.

FIG. 4 shows a flat metal foil which is used as a diverting element 26, 27 for positive electrode 23 and negative electrode 22 in the second embodiment of FIG. This metal foil has a perforated or reticular structure at a thickness of 20 µm.

5 shows a third embodiment of a battery cell 40 according to the invention in an exploded state. This third embodiment differs from the two considered embodiments in that the positive electrode 44 is covered by sheath 13. In this case, the surface extent of sheath 13 exceeds the surface extent of positive electrode 44, the boundary 14 of which is shown in FIG. 5 by a dotted line. Two layers 15, 16 of the shell 13 covering both sides of the positive electrode 44 are connected to each other at the reverse edge of the positive electrode 44 by an edge connection 17. Both negative electrodes 45 are not covered by the shell. The electrodes 44 and 45 can make contact through their leads 46, 47.

Example 1: Preparation of control electrolyte.

Used in the examples described below, the control electrolyte was prepared by the method disclosed in the description of the patent EP 2954588 B1 (indicated below as [V2]). First, lithium chloride (LiCl) was dried in vacuum at 120°C for three days. The aluminum particles (Al) were dried in vacuum for two days at 450°C. LiCl, aluminum chloride (AlCl ₃ ) and Al were mixed together in a molar ratio of AlCl ₃ :LiCl:Al = 1:1.06:0.35 in a glass vessel with a gas outlet. Then this mixture was gradually thermally processed until a salt melt was obtained. After cooling, the resulting salt melt was filtered, cooled to room temperature, and SO ₂ was added until the required molar ratio between SO ₂ and LiAlCl ₄ was reached. The control electrolyte thus obtained had the composition LiAlCl ₄ * × SO ₂ , while × depended on the amount of SO ₂ supplied.

Example 2 Preparation of SO ₂ electrolyte for a battery cell in four embodiments 1, 2, 3 and 4.

For the experiments described below, in the four exemplary embodiments 1, 2, 3 and 4, electrolytes based on SO ₂ were prepared (hereinafter referred to as electrolytes 1, 2, 3 and 4). First, four different first conductive salts were prepared for this according to the formula (1) using the method described in the following sources of information [V3], [V4] and [V5]:

[V3] „I. Crossing, Chem. Eur. J. 2001, 7, 490;

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

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

These four different first conductive salts of formula (1) are referred to below as compounds 1, 2, 3 and 4. They come from the polyfluoroalkoxyaluminate series and were prepared according to the following reaction equation based on LiAlH ₄ and the corresponding alcohol R-OH in hexane, where R ¹⁼ R2 ^{= R3} = ^R4 .

Hexane

As a result, the following compounds 1, 2, 3, 4 are formed below with the total and structural formulas

To purify compounds 1, 2, 3, 4 were first subjected to recrystallization. As a result, the remains of the LiАlH ₄ reagent were removed from the first salt, which increases the electrical conductivity of the electrolyte, since this reagent can probably lead to the formation of a spark when interacting with possibly present traces of water in SO ₂ . Then compounds 1, 2, 3, 4 were dissolved in SO ₂ . It was noted that compounds 1, 2, 3, 4 are well soluble in SO ₂ . The preparation of electrolytes 1, 2, 3 and 4 was carried out at low temperature or under pressure in accordance with the following technological operations 14:

1) placing the corresponding connection 1, 2, 3, 4 in a pressure flask with a riser,

2) evacuation of the pressure flask,

3) liquid SO ₂ inlet,

4) repeat operations 2+3 until a final amount of SO ₂ is introduced.

The concentration of compounds 1, 2, 3, 4 in electrolytes 1, 2, 3, 4 was 0.6 mol/l (amount of substance per 1 liter of electrolyte), unless otherwise indicated in the description of the experiment. When using electrolytes 1, 2, 3, 4 and the control electrolyte, the experiments described below were carried out.

Example 3. Production of tested whole battery cells.

The whole battery cells used in the experiments described below are battery cells with two negative electrodes and one positive electrode, which were separated by a divider. The positive electrodes contained an active material (indicated in the corresponding experiment), a conduction activator and a binder.

The negative electrodes studied contained an active material, which will be named in the corresponding description of the experiment. Additionally, the negative electrodes may contain a binder and/or a conductive additive. The outlet element of the positive and negative electrodes consisted of nickel. Tables 3a and 3b indicate which negative electrode active materials were tested.

The tested whole battery cells were filled with the electrolyte necessary for the experiments, i.e. either control electrolyte or electrolytes 1, 2, 3, 4.

Several experiments were made for each experiment, i.e. 2 to 4 identical whole battery cells under test. The results obtained during the experiments are, respectively, the average values obtained on the basis of the measured values for identical tested whole cells of the battery.

Example 4. Measurement of the tested whole cells of the battery. Coating layer capacity:

The capacity consumed during the first cycle to form a coating layer on the negative electrode is an important criterion for the quality of the battery cell (battery cell). This coating layer is formed the first time the entire battery cell under test is charged at the negative electrode. The formation of the coating layer irreversibly consumes lithium ions (the capacitance of the coating layer), as a result of which the whole battery cell under test has less capacity for subsequent cycles. Theoretically, the capacitance of the coating layer in % consumed during the formation of the coating layer on the negative electrode is calculated by the following formula:

Coating capacity (theoretical in %) = (Q _lad (x mAh) - Q _ent (y mAh)) / Q _NEL (GI (x mAh)) - Q _ent (y mAh)) / QNEL.

Q _lad describes the amount of charge specified in the corresponding experiment, expressed in mA⋅h; Q _ent describes the amount of charge, in mAh, that was obtained when the whole battery cell under test was subsequently discharged. QNEL means the theoretical capacitance of the negative electrode used. The theoretical capacity is, for example, 372 mAh/g for graphite.

The nominal capacitance is obtained by subtracting the capacitance of the coating layer

(Qiad (x mAh) - Q _en t (y mAh)) from the theoretical capacitance of the positive electrode.

discharge capacity.

When measuring in the tested whole cells of the battery, for example, the discharge capacity is determined by the number of cycles.

To do this, the tested whole cells are charged at a certain strength of the charging current until a certain upper potential is reached. The corresponding defined upper potential is maintained for such a long time until the charging current drops to a certain value. Then, the discharge occurs at a certain strength of the discharge current until a certain discharge potential is reached. With this charging method, we are talking about I/U (current / voltage) charging. Depending on the number of cycles required, this process may be repeated.

The upper potentials or discharge potential and the corresponding current during charging or discharging were determined during the experiments. The indicator to which the charging current should decrease during the experiments is described.

The concept of "upper potential" is used as a synonym for the concepts of "charging potential", "charging voltage", "end-of-charge voltage" and "upper potential limit". These terms refer to the voltage/potential to which a battery cell or battery is charged using a charger.

Preferably, the battery is charged at a C/2 current rate and a temperature of 22°C. At a charging or discharging rate of 1C, the nominal capacity of a battery cell is, by definition, charged or discharged in one hour. Accordingly, the charging rate C/2 means a charging time of 2 hours.

The concept of "discharge potential" is synonymous with the concept of "low battery cell voltage". This indicates the voltage/potential to which the cell or battery is discharged by the charger. Preferably, the battery is discharged at a C/2 current rate and a temperature of 22°C.

The discharging capacity is derived from the discharging current and the time at which the end of discharging criteria is met. The corresponding figures show the average discharge capacity as a function of the number of cycles. These average discharging capacities are often normalized as the maximum capacity achieved in the relevant experiment and expressed as a percentage of the nominal capacity.

Experiment 1. Tested whole cells of a battery with different graphites as the active material of the positive electrode.

Using different graphites as the active material of the negative electrode, experiments were carried out with the tested whole cells of the battery according to example 3. Firstly, the capacity of the coating layer (graphite 1, 2, 3, 4) and, secondly, the discharge capacity were determined (graphite 1, 2, 3). The tested whole battery cells were filled with the electrolyte described in example 2.

The tested whole battery cells contained negative electrodes with the synthetic graphites given in Table 3, i.e. with graphites 1, 2, 3, 4 as active material. The positive electrodes contained lithium-nickel-manganese-cobalt oxide (NMK622) (graphite 1, 2, 3) and lithium iron phosphate as active material. Figure 6 shows the potential of the tested whole cells of the battery in Volts when charging the negative electrode, as a function of capacity, correlated with the theoretical capacity of the negative electrode. The four curves shown show the average results of several experiments with the above-described whole cell test subjects. The curve of the whole battery cell under test with graphite 4 shows slightly lower potentials due to the different active material of the positive electrode. First, the tested whole battery cells were charged with a current of 15 mA until a capacity of 125 mAh (Qi _ad ) was reached. This was followed by the discharge of the tested whole battery cells with a current of 15 mA until a potential of 2.5 V was reached. In this case, the discharge capacity (Q _ent ) was determined.

The obtained indicators of capacitance of the cover layer (in % of the theoretical capacity of the negative electrode) were 6.58% for graphite 1, 4.29% for graphite 2, 5.32% for graphite 3 and 7.27% for graphite 4. Compared with existing systems with organic electrolytes, these are excellent indicators.

By means of the test whole battery cells containing graphite 1, 2 and 3, the discharge capacity indicators were determined in subsequent cycles. To determine the discharge capacity (see example 4), the tested whole battery cells were charged with a current of 100 mA until an upper potential of 4.4 V was reached. The corresponding upper potential was maintained until the charging current decreased to 40 mA. This was followed by a discharge with a current of 100 mA until a discharge potential of 2.5 V was reached.

Figure 7 shows the average values of the discharge capacity, normalized to 100% of the starting capacity of the three tested whole battery cells, as a function of the number of cycles. These average discharge capacities are expressed as a percentage of the nominal capacity. The tested whole battery cells with different graphites showed very good stability of the discharge capacity over the number of cycles. In the tested whole battery cells with graphite 1 and 2, 96% of the discharge capacity was achieved at a cycle of 250. In the tested whole battery cells with graphite 2, it was 93%.

Experiment 2

Graphite 1 as the active material of the negative electrode in the tested whole battery cells with electrolyte 1 and, in comparison with the tested whole battery cells with a reference electrolyte.

Using graphite 1 as the active material, experiments were carried out for two tested whole battery cells according to example 3. One tested whole battery cell was filled with electrolyte 1 described in example 2, the other contained a control electrolyte of the composition LiAlCl ₄ × 6SO ₂ . The positive electrodes contained lithium-nickel-manganese-cobalt oxide (NMK622) as an active material. Determined, firstly, the characteristics of the capacity of the coating layer, and secondly, the characteristics of the discharge capacity.

FIG. 8 shows the potential of the whole battery cell under test in Volts when the negative electrode is being charged, as a function of the capacitance relative to the theoretical capacitance of the negative electrode. The two curves shown show the average results of several experiments using the test whole battery cells described above.

First, whole cells under test were charged with a current of 15 mA until a capacity of 125 mAh (Qiad) was reached. Then, the tested whole battery cells were discharged with a current of 15 mA until a potential of 2.5 V was reached. In this case, the discharge capacity (Qent) was determined.

The obtained indicators of the capacity of the coating layer (in % of the theoretical capacity of the negative electrode) were 6.58% for graphite 1 in the tested whole battery cell with electrolyte 1 and 8.30% for graphite 1 in the tested whole battery cell with control electrolyte. The advantage of the electrolyte 1 in combination with graphite 1 resulted in a clearly reduced capacitance of the coating layer.

Using the same tested whole battery cells, the discharge capacity was determined during subsequent cycles. To determine the discharge capacity (see example 4), the tested whole battery cells were charged with a current of 100 mA until an upper potential of 4.4 V was reached. The corresponding upper potential was maintained for a time until the charging current decreased to 40 mA. This was followed by discharging using a current of 100 mA until a discharge potential of 2.5 V was reached.

Figure 9 shows the average discharge capacity, normalized to 100% of the starting capacity of the two tested whole battery cells. These average discharge capacities are expressed as % of nominal capacity. The tested whole battery cells with different electrolytes had different values of the discharge capacity during the cycles. In the tested whole battery cells with graphite 1 and electrolyte 1, it was achieved at a cycle of 280

98.4% discharge capacity with nearly flat curve. The tested whole battery cell with graphite 1 and reference electrolyte reached 96.8% with a subsequent, slightly falling trend.

Experiment 3. Formation of a coating layer on graphite 2, 3, and 4 in battery half-cells with a control electrolyte.

To conduct preliminary experiments to study the capacitance of the coating layer, experiments with battery half-cells were carried out at room temperature using both negative electrodes containing graphite 2 and 3 as an active material and using a negative electrode containing graphite 4 as an active material. The battery half cells were filled with a control electrolyte of composition LiAlCl ₄ × 1.5 SO ₂ and contained a lithium electrode as a reference electrode. Such electrochemical experiments with battery half cells are, because of their simplicity and the associated low experimental costs, standard experiments for characterizing electrodes.

Battery half-cells were repeatedly charged and discharged with a current of 10 mA (respectively, 1C to practical capacity). From the loss of capacity during the first three cycles, the capacity of the coating layer was calculated.

Figure 10 shows the curves of the coating layer and the capacitance of the coating layer of two experimental half-cells. The capacity of the coating layer in the control electrolyte medium was 12.1% for the battery half-cell with graphite 1, 10.3% with graphite 3, and 15.5% with graphite 4 of the theoretical capacity of the negative electrode. These values are noticeably higher than those determined in experiment 1 for identical graphites in electrolyte 1.

Experiment 4. Graphite 1 as the active material of the negative electrode in the tested whole battery cells with electrolyte 1, 3 and 4.

To study electrolytes 1, 3 and 4 in combination with graphite 1 as the active material of the negative electrode, different experiments were carried out. Firstly, the capacity of the coating layer with electrolytes 3 and 4 was determined, and secondly, the discharge capacity was determined with all three electrolytes 1, 3, 4.

To determine the capacitance of the coating layer, two test whole battery cells were filled with the electrolytes 3 and 4 described in Example 2. Two test whole battery cells contained graphite 1 as the negative electrode active material. The positive electrodes had lithium-nickel-manganese-cobalt oxide (NMK622) as an active material.

FIG. 11 shows, in Volts, the potential of whole battery cells under test when the negative electrode is being charged, as a function of capacitance relative to the theoretical capacitance of the negative electrode. The two curves shown show the average results of several experiments with the above-described whole cell test subjects. First, whole cells under test were charged with a current of 15 mA until a capacity of 125 mAh (Qiad) was reached. After that, the tested whole battery cells were discharged with a current of 15 mA until a potential of 2.5 V was reached. In this case, the discharge capacity (Qent) was determined.

The obtained indicators of the capacitance of the coating layer (in % of the theoretical capacity of the negative electrode) amounted to 17.77% in electrolyte 3 and 20.02% in electrolyte 4. With slightly increased values of the capacitance of the coating layer in electrolytes 3 and 4, very reliable operation of the battery cell with these electrolytes.

For the discharge experiments, three test whole battery cells were filled in accordance with example 3 with electrolytes 1, 3 and 4 described in example 2. The test whole battery cells had lithium-nickel-manganese-cobalt oxide (NMC) as the positive electrode active material and as the active material of the negative electrode, graphite 1. To determine the discharge capacity (see example 4), the tested whole battery cells were charged with a current of 15 mA until a capacity of 125 mAh was reached. This was followed by a discharge with a current of 15 mA until a discharge potential of 2.5 V was reached.

Fig. 12 shows the potential curve during discharging through the discharged charge volume in % (% of the maximum charge (discharge)). All tested whole battery cells had a flat discharge curve, which is necessary for the proper operation of the battery cell.

Experiment 5. Whole battery cells tested containing mixtures of _SiOx , 5.0%/graphite 3, _SiOx 17.3%/graphite 3, and _SiOx , 24.%/graphite 3 as negative electrode active materials.

As follows from table 36, the expression SiO _x , 5% / graphite 3 means mixtures of SiO _x (5 wt.%) and graphite 3 (95 wt.%), and SiO _x consists of a mixture of components: Si, SiO and Si02. Other described mixtures of SiO _x / graphite 3 contain SiO _x in the amount of 17.3 wt. % or 24.0 wt. % SiOx and corresponding amounts of graphite 3. Three different mixtures were used in the three tested battery cells according to Example 3 as the negative electrode active material and experiments were carried out. In this case, firstly, the capacitance of the coating layer and, secondly, the discharge capacity were determined. Whole battery cells to be tested were filled with the electrolyte 1 described in Example 2. The positive electrodes contained lithium-nickel-manganese-cobalt oxide as an active material.

13 shows the potential of three whole battery cells under test in Volts during negative electrode charging as a function of capacitance relative to the theoretical negative electrode capacitance. The curves shown represent the average results of several experiments using the test whole cells described above. First, whole battery cells under test were charged with a current of 15 mA until a capacity of 125 mAh (Qiad) was reached. This was followed by discharging the tested whole battery cells with a current of 15 mA until a potential of 2.8 V was reached. In this case, the discharge capacity (Qent) was determined.

The obtained values of the capacitance of the coating layer (in % of the theoretical capacitance of the negative electrode) were 12.69% for a mixture of SiO _x 5.0% / graphite 3, 15.29% for a mixture of SiOx 17.3% / graphite 3 and 14.41% for a mixture of SiO _x 24.0% / graphite 3.

Using the same test whole battery cells during the next ten cycles, the discharge capacity was determined. To determine the discharge capacity (see example 4), the tested whole battery cells were charged with a current of 40 mA until an upper potential of 4.4 V was reached. Then, a discharge with a current of 40 mA followed until a discharge potential of 2.8 V was reached. discharge capacity values for ten cycles, normalized to 100% of the starting capacity of the tested whole battery cells, as a function of the number of cycles. These average values of the discharge capacity are expressed respectively as a percentage of the nominal capacity. All three battery cells had a flat discharge capacity curve.

Experiment 6. Tested whole battery cells containing nano-silicon/graphite as the active material of the negative electrode.

Using the nano-silicon/graphite mixtures shown in Table 36 as the negative electrode active material, experiments were carried out with whole cell test subjects according to Example 3. Firstly, the capacitance of the coating layer and, secondly, the discharge capacity were determined. The tested whole battery cells were filled with the electrolyte described in example 2.

The four tested whole battery cells contained negative electrodes either with a mixture of nano-silicon (5 wt.%) and graphite 3 (95 wt.%), or with a mixture of nano-silicon (2.4 wt.%) and graphite 1 ( 97.5 wt.%), either with a mixture of nano-silicon (5.0 wt.%) and graphite 1 (95.0 wt.%), or with a mixture of nano-silicon (10 wt.%) and graphite 1 (90 wt. %). The positive electrodes contained lithium-nickel-manganese-cobalt oxide as an active material.

FIG. 15 shows the potential of the whole battery cells under test in Volts when the negative electrode is charged with respect to lithium as a function of the capacity related to the theoretical capacity of the negative electrode. The four curves depicted represent the average results of several experiments with the above-described whole battery cell test subjects. First, whole battery cells under test were charged with a current of 15 mA until a capacity of 125 mAh (Qiad) was reached. This was followed by discharging the test whole battery cells with a current of 15 mA until a potential of 2.8 V was reached. In this case, the discharge capacity (Qent) was determined.

The obtained indicators of the capacitance of the coating layer (in % of the theoretical capacity of the negative electrode) amounted to 12.47% for a mixture of nano-silicon (5 wt.%) and graphite 3 (95 wt.%), 9.91% for a mixture of nano- silicon (2.5 wt.%) and graphite 1 (97.5 wt.%), 11.63% for a mixture of nano-silicon (5.0 wt.%) and graphite 1 (95.0 wt.%) and 14.77% for a mixture of nano-silicon (10 wt.%) and graphite 1 (90 wt.%).

Using the same test whole battery cells, the discharge capacity was determined for the next ten cycles. To determine the discharge capacity (see example 4), the tested whole battery cells were charged with a current of 40 mA until an upper potential of 4.4 V was reached. the capacity of the three whole battery cells under test at ten cycles as a function of the number of cycles. These average discharge capacities are expressed as % of nominal capacity. All four battery cells had a flat discharge capacity curve.

Experiment 7. Determination of the electrical conductivity of electrolytes 1, 3 and 4.

To determine the electrical conductivity, electrolytes 1, 3, 4 were prepared with different concentrations of compounds 1, 3, and 4. The electrical conductivity of the electrolytes was determined for each concentration of different compounds, and the conductive measurement method was used. In this case, after thermostating, the two-electrode sensor was kept in the solution with contact and measured in the range from 0 to 50 mS/cm. During the measurement, care was taken that the sensor could react with the electrolyte solution containing SO ₂ .

17 shows the conductivity of the electrolyte 1 as a function of the concentration of compound 1. The maximum value of the conductivity can be seen at a concentration of compound 1 from 0.6 to 0.7 mol/l, equal to about 37.9 mS/cm. In comparison, prior art organic electrolytes such as LP30 (1 M LiPF ₆ / EC-DMC (1 : 1 by weight) have a conductivity of only 10 mS/cm.

Figures 18 (electrolyte 3) and 19 (electrolyte 4) show the conductivity values of electrolytes 3 and 4 derived at different concentrations.

When using electrolyte 4, a maximum of 18 mS/cm was obtained at a concentration of conductive salt, which increases the electrical conductivity of the electrolyte, equal to 1 mol/l. The maximum electrical conductivity of electrolyte 3 was 0.5 mS/cm at a salt concentration that increases the electrical conductivity of the electrolyte, equal to 0.6 mol/l. Although electrolyte 3 showed lower electrical conductivity, charging and discharging of the test whole battery cell, as in experiment 4, was perfectly possible.

Experiment 8. State at low temperature.

In order to determine the state of the electrolyte 1 at a low temperature compared to the control electrolyte, two test whole battery cells were made in accordance with Example 3. One tested whole battery cell was filled with the control electrolyte of the composition LiAlCl ₄ * 6SO ₂ , the other tested whole battery cell was filled with electrolyte 1. The tested whole battery cell with the control electrolyte contained lithium iron phosphate (LIF) as an active material, the tested whole battery cell with electrolyte 1 contained lithium-nickel-manganese-cobalt oxide (NMC) as the positive electrode active material. Both test whole battery cells contained graphite 1 as the negative electrode active material.

The test whole battery cells were charged at 20°C to 3.6 V (LVF) or 4.4 V (NMC) and again discharged at the corresponding test temperature to 2.5 V. The discharge capacity obtained at 20°C was 100%. The temperature during discharging was lowered by a temperature step of 10 K. The resulting discharge capacity was described as % of the discharge capacity at 20°C. Since the low temperature discharge is almost independent of the positive and negative electrode active materials used, the results can be transferred to any combination of active materials. Table 4 shows the results.

The tested whole battery cell with electrolyte 1 showed very good low temperature properties. At -20°C the capacity was still 82%, at -30°C still 73%. Even at -40°C, the discharge capacity was still 61%. In contrast, the test whole battery cell with reference electrolyte only showed the ability to be discharged down to -10°C. This achieved a capacity of 21%. At lower temperatures, the battery cell with reference electrolyte was no longer discharged.

Claims (80)

1. Battery cell (2, 20, 40) containing active metal, at least one positive electrode (4, 23, 44), at least one negative electrode (5, 22, 45), housing (1, 28 ) and electrolyte, while the negative electrode contains an active material selected from the group: - carbon inclusion material, alloy forming active material, - intercalary material without carbon content, - conversion active material, and the electrolyte is based on SO ₂ and contains at least one salt that increases the electrical conductivity of the electrolyte, and has the formula (I):

Formula (I), where - M is a metal selected from the group consisting of alkali metals, alkaline earth metals, metals of group 12 of the Periodic Table of the Elements and aluminum; - x is an integer from 1 to 3; - said substituents R ¹ , R ² , R ³ and R ⁴ are independently selected from the group consisting of C ₁ -C ₁₀ alkyl, C ₂ -C ₁₀ alkenyl, C ₂ -C ₁₀ alkynyl, C ₃ -C ₁₀ cycloalkyl, C ₆ -C ₁₄ aryl and C ₅ -C ₁₄ heteroaryl; and - Z represents aluminum or boron. 2. Battery cell (2, 20, 40) according to claim 1, wherein the carbon inclusion material is selected from the group formed from: - graphite, - natural graphite, in particular flake or rounded natural graphite, - synthetic graphite, in particular mesophase graphite, - graphitized mesocarbon microgranules, - carbon-coated graphite, - amorphous carbon. 3. Battery cell (2, 20, 40) according to claim 1 or 2, wherein the alloy-forming active material is selected from: - a group formed from lithium storage metals and metal alloys, preferably Si, Ge, Sn, SnCo _x C _y , SnSi _x , or a group formed from oxides of lithium-accumulating metals and metal alloys, preferably SnO _x , SiO _x , and oxide glasses Sn, Si. 4. The battery cell (2, 20, 40) according to claim 1, wherein the alloy-forming active material consists of silicon, or oxides of silicon, or mixtures of silicon and its oxides. 5. Battery cell (2, 20, 40) 1 each, in which the negative electrode (5, 22, 45) contains at least one alloy-forming anode-active material, in particular an alloy-forming with lithium in combination with at least one containing material of carbon, while combinations of silicon and/or silicon oxides with graphite are preferred. 6. Battery cell (2, 20, 40) according to any one of paragraphs. 1-3, in which the carbon-free intercalary material is lithium titanate, in particular Li ₄ Ti ₅ O ₁₂ . 7. Battery cell (2, 20, 40) according to any one of paragraphs. 1-4, wherein the conversion active material is selected from: - a group formed from manganese oxides (MnO _x ), iron oxides (FeO _x ), cobalt oxides (CoO _x ), nickel oxides (NiO _x ) and copper oxides (CuO _x ), or - a group consisting of magnesium hydride (MgH ₂ ), titanium hydride (TiH ₂ ), aluminum hydride (AlH ₃ ) and triple hydrides based on boron, aluminum and magnesium. 8. Battery cell (2, 20, 40) according to any one of the preceding claims, wherein the positive electrode (4, 23, 44) contains as active material at least one compound, preferably of the composition A _x M' _y M" _z O _a , where: - A - at least one metal selected from the group consisting of alkali metals, alkaline earth metals, metals of group 12 of the Periodic Table of the Elements or aluminum, - M' - at least one metal selected from the group consisting of the elements: Ti, V, Cr, Mn, Fe, Co, Ni, Cu, Zn, - M" - at least one element selected from the group consisting of elements of groups: 2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13, 14, 15, 16 of the Periodic system elements, - x and y - independently of each other, the number is greater than 0, - z is a number that is greater than or equal to 0, - a is a number greater than 0. 9. Battery cell (2, 20, 40) according to claim 8, wherein the compound has the composition Li _x M' _y M" _z O _a where: M' means manganese, M" means cobalt, wherein x, y, z are preferably 1 and equally preferably 4. 10. Battery cell (2, 20, 40) according to claim 8 or 9, wherein the compound has the composition Li _x M' _y M" _z O _a where: M' means nickel and manganese, M" means cobalt, and which has the formula Li _x Ni _y1 Mn _y2 Co _z O _a . 11. Battery cell (2, 20, 40) according to claim 8, in which the compound has the composition Li _x M' _y M" ¹ _z1 M" ² _z2 O ₄ where: M" ² means phosphorus and z2 is equal to 1. 12. Battery cell (2, 20, 40) according to claim 11, wherein the compound has the composition Li _x M' _y M" ¹ _z1 PO ₄ where: M' means iron, M'' ¹ is manganese, while the compound preferably has the composition Li(Fe _0.3 Mn _0.7 )PO ₄ . 13. Battery cell (2, 20, 40) according to any one of the previous paragraphs, in which the substituents R ¹ , R ² , R ³ , R ^{4 of} the first conductive salt are selected independently of each other from the group consisting of: - C ₁ -C ₆ alkyl; preferably C ₂ -C ₄ alkyl; more preferably alkyl groups 2-propyl, methyl and ethyl; - C ₂ -C ₆ alkenyl; preferably C ₂ -C ₄ alkenyl; more preferably ethenyl and propenyl alkenyl groups; - C ₂ -C ₆ alkynyl; preferably C ₂ -C ₄ alkynyl; - C ₃ -C ₆ cycloalkyl; - phenyl and - C ₅ -C ₇ heteroaryl. 14. Battery cell (2, 20, 40) according to any one of the preceding paragraphs, wherein at least one of the substituents R ¹ , R ² , R ³ , R ^{4 of} the first conductive salt is replaced by at least one fluorine atom and/or at least one chemical group, wherein the chemical group is selected from the group consisting of C ₁ -C ₄ alkyl, C ₂ -C ₄ alkenyl, C ₂ -C ₄ alkynyl, phenyl and benzyl. 15. The battery cell (2, 20, 40) according to any one of the preceding claims, wherein at least one of the substituents R ¹ , R ² , R ³ , R ^{4 of} the first conductive salt is a CF ₃ group or an OSO ₂ CF ₃ group . 16. Battery cell (2, 20, 40) according to any one of the preceding claims, wherein the first conductive salt is selected from the group consisting of:

Li[B(OCH ₂ CF ₃ ) ₄ ] Li[B(OCH(CF ₃ ) ₂ ) ₄ ] Li[Al(OC(CF ₃ ) ₃ ) ₄ ]

Li[Al(OC(CH ₃ )(CF ₃ ) ₂ ) ₄ ] Li[Al(OCH(CF ₃ ) ₂ ) ₄ ]. 17. Battery cell (2, 20, 40) according to any one of the preceding claims, wherein the electrolyte contains at least one conductive second salt different from the first conductive salt of formula (I). 18. The battery cell (2, 20, 40) according to claim 17, wherein the second conductive salt in the electrolyte is an alkali metal compound, in particular a lithium compound selected from the group consisting of aluminate, halide, oxalate, borate, phosphate, arsenate and gallate. 19. The battery cell (2, 20, 40) according to claim 17 or 18, wherein the second conductive salt in the electrolyte is lithium tetrahaloaluminate, in particular lithium tetrachloroaluminate. 20. The battery cell (2, 20, 40) according to any one of the preceding claims, wherein the electrolyte contains at least one additive. 21. Battery cell (2, 20, 40) according to claim 20, wherein said additive is selected from the group consisting of vinylene carbonate and its derivatives, vinylethylene carbonate and its derivatives, methylethylene carbonate and its derivatives, (bisoxalate) lithium borate, difluoro( lithium oxalate)borate, lithium tetrafluoro(oxalate)phosphate, lithium oxalate, 2-vinylpyridine, 4-vinylpyridine, cyclic exomethylene carbonates, sultones, cyclic and acyclic sulfonates, acyclic sulfites, cyclic and acyclic sulfinates, organic esters, inorganic acids, acyclic and cyclic alkanes, where acyclic and cyclic alkanes have a boiling point of at least 36° C. at 1 bar pressure, aromatic compounds, halogenated cyclic and acyclic sulfonyl imides, halogenated cyclic and acyclic phosphate esters, halogenated cyclic and acyclic phosphines, halogenated cyclic and acyclic phosphites, gal halogenated cyclic and acyclic phosphazenes, halogenated cyclic and acyclic silylamines, halogenated cyclic and acyclic esters, halogenated cyclic and acyclic amides, halogenated cyclic and acyclic anhydrides, and halogenated organic rings. 22. Battery cell (2, 20, 40) according to any of the preceding claims, wherein the electrolyte has the following composition, in relation to the total weight of the electrolyte: (i) 5-99.4 wt% sulfur dioxide, (ii) 0.6-95 wt.% of the first salt, which increases the electrical conductivity of the electrolyte, (iii) 0-25 wt.% of the second salt, which increases the electrical conductivity of the electrolyte, (iv) 0-10 wt.% additive. 23. Battery cell (2, 20, 40) according to any one of the previous paragraphs, in which the concentration of the first conductive salt is from 0.01 to 10 mol/l, preferably from 0.05 to 10 mol/l, preferably from 0 .1 to 6 mol/l, particularly preferably 0.2 to 3.5 mol/l, based on the total electrolyte volume. 24. Battery cell (2, 20, 40) according to any one of the previous paragraphs, in which the electrolyte contains at least 0.1 mol SO ₂ , preferably at least 1 mol SO ₂ , preferably at least 5 mol SO ₂ , preferably at least 10 mol SO ₂ , particularly preferably at least 20 mol SO ₂ per mol of conductive salt. 25. Battery cell (2, 20, 40) according to any of the previous paragraphs, in which the active metal is: - an alkali metal, in particular lithium or sodium, - alkaline earth metal, in particular calcium, - a metal from group 12 of the Periodic Table of the Elements, in particular zinc, - aluminum. 26. Battery cell (2, 20, 40) according to any one of the preceding claims, wherein the positive electrode (4, 23, 44) contains at least one metal compound selected from the group consisting of metal oxide, metal halide and phosphate metal, and the metal of the metal compound is preferably a transition metal of serial number from 22 to 28 of the Periodic Table of the Elements, in particular cobalt, nickel, manganese or iron. 27. The battery cell (2, 20, 40) according to any one of the preceding claims, wherein the positive electrode (4, 23, 44) contains at least one metal compound having the chemical structure of a spinel, a layered oxide capable of converting a compound, or polyanionic compound. 28. The battery cell (2, 20, 40) according to any one of the previous paragraphs, in which the positive electrode (4, 23, 44) and/or the negative electrode (5, 22, 45) contain a discharge element (26, 27), performed preferably: - either flat in the form of a metal sheet or metal foil, - or three-dimensional in the form of a porous metal structure, in particular metal foam (18). 29. The battery cell (2, 20, 40) according to any one of the previous claims, in which the positive electrode (4, 23, 44) and/or the negative electrode (5, 22, 45) contain at least one binder, preferably fluorinated a binder, in particular polyvinylidene fluoride, and/or a terpolymer consisting of tetrafluoroethylene, hexafluoropropylene and vinylidene fluoride, or a binder consisting of a polymer formed by monomeric structural units of a conjugated carboxylic acid, or an alkali metal, alkaline earth metal or ammonium salt of this conjugated carboxylic acid, or a combination thereof, or a binder consisting of a polymer based on monomeric structural units of styrene and butadiene, or a binder from the group of carboxymethyl celluloses, wherein the binder is preferably present at a concentration of at most 20% by weight, preferably at most 15% by weight, preferably at most 10% by weight, preferably at most 7% by weight, preferably at most 5% by weight, particularly preferably at most 2 wt.% of the total weight of the positive electrode. 30. Battery cell (2, 20, 40) according to any of the previous paragraphs, which contains a plurality of negative electrodes (5, 22, 45) and a plurality of positive electrodes (4, 23, 44) located alternately in the housing (1, 28 ), and positive electrodes (4, 23, 44) and negative electrodes (5, 22, 45) are preferably electrically separated from each other by separators (11).

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