RU2784564C1 - Accumulator battery element - Google Patents

Abstract

FIELD: electrical engineering.

SUBSTANCE: invention relates to the field of electrical engineering, namely to a lithium-ion accumulator battery, which has increased stability and reliability due to the use of an electrolyte based on SO₂, which shows good characteristics at low temperatures. Accumulator battery element (2, 20, 40) contains active metal, at least one positive electrode (4, 23, 44), at least one negative electrode (5, 22, 45), case (1, 28), and an electrolyte. In this case, specified positive electrode (4, 23, 44) contains at least one compound in the form of an oxide layer as active material, and the specified electrolyte is made based on SO₂, and it contains at least one conductive salt containing an organic additive selected from a group: C₁-C₁₀ alkyl, C₂-C₁₀ alkenyl, C₂-C₁₀ alkynyl, C₃-C₁₀ cycloalkyl, C₆-C₁₄ aryl, and C₅-C₁₄ heteroaryl, related to aluminum or boron. An accumulator battery with such an element provides an increase in charging and discharging cycles.

EFFECT: increase in operational reliability and service life of a battery without destruction of an electrolyte.

25 cl, 15 dwg, 5 tbl, 7 ex

Description

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

Battery cells are of great importance in many areas of technology. They are often used in applications where only small battery cells with relatively low amperages are required, such as to operate cell phones. In addition, there is a great need for larger battery cells for high energy applications, with energy storage in batteries being of particular importance for electric vehicles.

High energy density is an important requirement for these types of battery cells. This means that the battery cell must contain as much electricity as possible per unit of weight and volume. Lithium has proven to be particularly useful as an active metal for this purpose. Active metal A battery cell is a metal whose ions in the electrolyte migrate to the negative or positive electrode when the cell is being charged or discharged and participate in the electrochemical processes that take place there. These electrochemical processes lead directly or indirectly to the emission of electrons into the external circuit or to the absorption of electrons from the external circuit. Battery cells containing lithium as the active metal are also referred to as lithium-ion cells. The energy density of these lithium-ion cells can be increased either by increasing the specific capacitance of the electrodes or by increasing the cell voltage.

Both positive and negative electrodes of lithium-ion cells are made in the form of plug-in electrodes. The term "inclusion electrode" in the sense of the present invention refers to electrodes that have a crystalline structure in which active material ions can be stored and removed during operation of the lithium ion cell. This means that electrode processes can occur not only on the electrode surface, but also inside the crystal structure. Both electrodes are typically less than 100 µm thick and therefore very thin. When charging a lithium-ion cell, active metal ions are removed from the positive electrode and stored in the negative electrode. The reverse process occurs when a lithium-ion cell is discharged.

The electrolyte is also an important functional element of each battery cell. It usually includes a solvent or mixture of solvents and at least one conductive salt. For example, solid electrolytes or ionic liquids do not contain a solvent, but only a conductive salt. The electrolyte is in contact with the positive and negative electrodes of the battery. At least one conductive salt ion (anion or cation) is sufficiently mobile in the electrolyte such that charge transfer between the electrodes required for the battery cell to function can occur via ionic conduction. The electrolyte undergoes oxidative electrochemical degradation at a certain high battery cell voltage. This process often leads to the irreversible destruction of the electrolyte components and, as a result, to the failure of the battery cell. Recovery processes can also decompose the electrolyte when the voltage drops below a certain level. To avoid these processes, the positive and negative electrodes are chosen so that the cell voltage is lower or higher than the decomposition voltage of the electrolyte. Thus, the electrolyte determines the voltage range within which the battery cell can operate reversibly, that is, be repeatedly charged and discharged.

Lithium-ion cells known from the prior art contain an electrolyte consisting of an organic solvent or mixture of solvents and a conductive salt dissolved therein. The conductive salt is a lithium salt such as lithium hexafluorophosphate (LiPF ₆ ). The solvent mixture may include, for example, ethylene carbonate (EC). Electrolyte LP57, having a composition of 1 M LiPF ₆ in EC:EMC 3:7, is an example of such an electrolyte. Due to the presence of an organic solvent or mixture of solvents, this type of lithium ion cells is also referred to as organic lithium ion cells.

The negative electrode of these organic lithium-ion cells consists of a carbon coating that is deposited on a copper discharge cell. The discharge cell provides the necessary electrically conductive connection between the carbon coating and the external circuit. The positive electrode consists of lithium cobalt oxide (LiCoO ₂ ) which is deposited on an aluminum discharge element.

It has long been known that unintentional overcharging of organic lithium-ion cells leads to irreversible decomposition of electrolyte components. Oxidative decomposition of the organic solvent and/or the conductive salt occurs at 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, as a consequence, the destruction of the organic lithium-ion cell. The vast majority of charging protocols for these organic lithium-ion cells use cell voltage as an indication of the end of charging. Thermal runaway accidents are especially likely with multi-cell battery packs in which multiple organic lithium-ion cells containing dissimilar capacities are connected in series.

Therefore, organic lithium-ion cells have problems in terms of their stability and long-term operational reliability. Safety risks are also caused, in particular, by the flammability of the organic solvent or solvent mixture. When an organic lithium ion cell catches fire or even explodes, the organic solvent in the electrolyte forms a combustible material. Additional measures must be taken to avoid such security risks. These measures include, in particular, very precise regulation of the charging and discharging processes of the organic lithium-ion cell and an optimized battery design. In addition, the organic lithium ion cell contains components that melt if the temperature rises unintentionally, and thus can flood the organic lithium ion cell with molten plastic. This prevents a further uncontrolled rise in temperature. However, these measures lead to an increase in production costs in the manufacture of an organic lithium ion cell and an increase in volume and weight. In addition, these measures reduce the specific energy of the organic lithium ion cell.

Another disadvantage of organic lithium ion cells is that any hydrolysis products formed in the presence of residual amounts of water are very aggressive towards battery cell components. For example, the conductive LiPF ₆ salt, which is often used in organic cells, produces a highly reactive, corrosive hydrogen fluoride (HF) by reacting with traces of water. For this reason, in the production of such battery cells containing an organic electrolyte, attention must be paid to minimizing the residual water content contained in the electrolyte and cell components. Therefore, said production is often carried out in expensive kilns at very low humidity. The issues described above regarding stability and long-term operational reliability are of particular importance for the development of organic lithium-ion cells, which, on the one hand, are characterized by a high level of energy and power density, and, on the other hand, are characterized by a very high degree of operational reliability and a very long service life. service life, including the particularly high number of charge and discharge cycles used.

To increase the energy density of organic lithium ion cells, new cathode materials have been tested in the prior art, i.e. new positive electrode materials that can cycle with a higher end-of-charge voltage, i.e. a higher top potential. Such materials are, for example, oxides of lithium, nickel, manganese, cobalt, which are also referred to as NMC for short. This is reported by the following publication:

"Oxygen release and its influence on the cycle stability of LiNi _x Mn _y Co _z O ₂ (NMC) cathode materials for lithium-ion batteries"

Roland Jung; Michael Metzger; Filippo Maglia; Christoph Stinner and Hubert A. Gasteigera.

Journal of The Electrochemical Society, 164(7) A1361-A1377 (2017)

This publication by Jung et al. is referred to below as [V1]. Jung et al. [V1] investigated various NMC materials having the composition NMC(xyz). Lowercase letters (xyz) in parentheses denote x, y, and z of the LiNi _x Mn _y Co _z O ₂ compound. In [V1], three different NMC cathode materials were tested in a cycle in an organic lithium ion cell containing the previously described LP57 electrolyte (1 M LiPF ₆ in EC: EMC 3:7) using different end-of-charge voltages. The charge end voltage is the voltage to which a single battery cell or a battery consisting of multiple battery cells is charged by the charger. Batteries are often charged at a certain charge current to a certain upper potential, that is, to the end-of-charge voltage. The corresponding upper potential is maintained until the charge current drops to a certain value. In [V1], respectively, 300 charge/discharge cycles were performed. Table 1 below shows the reduction in discharge capacity at the 5th cycle compared to the 300th cycle, indicated in %.

It can be seen from Table 1 that with NMC (111) and NMC (622) materials, there is a sharp decrease in capacity in cycles with an end-of-charge voltage of 4.6 V, since only 42% and 39% of the original capacity are achieved. The NMC (811) material was used in cycles up to 4.4 volts only, and a steady decrease in capacitance was also observed with increasing voltage at the end of charge. Thus, based on [V1], it can be established that organic lithium-ion cells containing NMC cathode materials can be used in cycles at a higher upper potential. However, the disadvantage is an undesirably large reduction in capacitance.

Therefore, a further development of the cells known from the prior art provides for the use of an electrolyte based on sulfur dioxide (SO ₂ ) instead of an organic electrolyte for battery cells. Battery cells containing an SO ₂ based electrolyte, among other things, have a high ionic conductivity. The term "SO ₂ -based electrolyte" in the sense of the present invention refers to electrolytes which contain SO ₂ not simply as an additive at low concentrations, but in which the ion mobility in the conductive salt contained in the electrolyte and which causes charge transfer is at least at least partially, to a large extent or even completely provided by SO ₂ . Thus, SO ₂ serves as a solvent for the conductive salt. The conductive salt can form a liquid solvate complex with gaseous SO ₂ , whereby the SO ₂ is bound and the vapor pressure is markedly reduced compared to pure SO ₂ . Low vapor pressure electrolytes are produced. Compared to the organic electrolytes described above, these SO ₂ based electrolytes have the advantage of being non-flammable. In this way, safety risks that may arise due to the flammability of the electrolyte can be eliminated.

For example, EP 1201004 B1 discloses an SO ₂ based electrolyte having the composition LiAlCl ₄ * SO ₂ in combination with a positive electrode made from LiCoO ₂ (hereinafter referred to as [V2]). [V2] suggests the use of additional salt to avoid damaging decomposition reactions such as the undesired formation of chlorine (Cl ₂ ) from lithium tetrachloraluminate (LiAlCl ₄ ) when said battery cell is recharged from an upper potential of 4.1 to 4.2 volts.

EP 2534719 B1 (hereinafter referred to as [V3]) also discloses an SO ₂ based electrolyte containing, inter alia, LiAlCl ₄ as the conductive salt. For example, said LiAlCU forms complexes of the formula LiAlCU * 1.5 mol SO ₂ or LiAlCl ₄ * 6 mol SO ₂ with SO ₂ . Lithium iron phosphate (LiFePO ₄ ) is used as the positive electrode in [V3]. LiFePO ₄ has a lower end-of-charge voltage (3.7 V) compared to LiCoO ₂ (4.2 V). In this battery cell, the problem of undesired recharge reactions does not arise, since the upper potential of 4.1 volts, which is harmful to the electrolyte, is not reached. A disadvantage that also occurs with these SO ₂ based electrolytes, among others, is that any hydrolysis products formed in the presence of residual amounts of water react with the battery cell components and thus lead to the formation unwanted by-products. For this reason, in the manufacture of such battery cells containing an SO ₂ -based electrolyte, attention should be paid to minimizing the residual water content contained in the electrolyte and cell components.

Another problem with SO ₂ -based electrolytes is that many conductive salts, in particular those also known for organic lithium ion cells, do not dissolve in SO ₂ . Measurements have shown that SO ₂ is a poor solvent for many conductive salts such as 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 ), lithium hexafluoroaluminate (Li ₃ hAlF 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 of these conductive salts in SO ₂ is about 10 ^-2 - 10 ^-4 mol/l (see Table 2). At such low salt concentrations, it can be assumed that at most only low electrical conductivities exist, which are not sufficient for useful operation of the battery cell.

To further improve the possible applications and properties of battery cells that contain an SO ₂ based electrolyte, the aim of the present invention is to find a battery cell containing an SO ₂ based electrolyte which, compared to prior art battery cells:

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

- has a stable coating layer on the negative electrode, due to which the capacitance of the coating layer should be low, and during further operation no reductive decomposition of the electrolyte should occur on the negative electrode;

contains an SO ₂ based electrolyte which exhibits good solubility for a conductive salt and is therefore a good ion conductor and electronic insulator so that ion transport can be facilitated and self-discharge can be minimized;

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

- resistant to various incorrect influences, such as electrical, mechanical or thermal;

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

- demonstrates improved electrical characteristics, in particular high energy density;

- has improved recharge and deep discharge and lower self-discharge; and

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

Such battery cells should in particular also have very good electrical energy and performance, high operational reliability and service life, in particular, have a large number of useful charge and discharge cycles without destroying the electrolyte during battery cell operation.

This goal is achieved by providing a battery cell containing the features of paragraph 1 of the claims of the present invention. Claims 2 to 25 describe advantageous improvements to the battery cell of the present invention.

The battery cell of the present invention comprises an active metal, at least one positive electrode, at least one negative electrode, a housing, and an electrolyte. Said positive electrode contains at least one compound in the form of an oxide layer as an active material. Said electrolyte is based on SO ₂ and contains at least one first conductive salt. Said first conductive salt has the formula (I).

In formula (I), M is a metal selected from the group consisting of alkali metals, alkaline earth metals, metals of group 12 of the Periodic Table of the Elements, and aluminum, x is an integer from 1 to 3. Substituents R1, R ² , R ³ are indicated and R4 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. The central Z atom is either aluminum or boron.

In the sense of the present invention, the term "oxide layer" refers to metal oxides which are selected from the α-NaFeO ₂ structural type. In this structural type, oxygen atoms occupy the lattice positions of a face-centered cubic lattice (the so-called fcc lattice), in which metal ions occupy the octahedral holes that are present in the lattice.

The SO ₂ -based electrolyte used in the battery cell of the present invention contains SO ₂ not only as an additive at a low concentration, but also at concentrations at which the ion mobility of the first conductive salt contained in said charge-transfer electrolyte is at least partially, to a large extent or even completely, is provided by SO ₂ . Said first conductive salt dissolves in said electrolyte and exhibits very good solubility therein. It can form a liquid solvate complex with gaseous SO ₂ in which SO ₂ is bound. In this case, the vapor pressure of the liquid solvate complex is markedly reduced compared to pure SO ₂ , resulting in the formation of electrolytes with low vapor pressure. However, it is also within the scope of the present invention that, depending on the chemical structure of said first conductive salt according to formula (I), no reduction in vapor pressure of said electrolyte according to the present invention may occur during manufacture. In the latter case, it is preferable that the production of the electrolyte according to the present invention is carried out at low temperature or under pressure. Said electrolyte may also contain a plurality of conductive salts of formula (I) which differ from one another in their chemical structure.

In the sense of the present invention, the term "C ₁ -C ₁₀ alkyl" includes linear or branched saturated hydrocarbon groups containing from one to ten carbon atoms. They include in particular methyl, ethyl, n-propyl, isopropyl, n-butyl, sec-butyl, isobutyl, t-butyl, n-pentyl, isopentyl, 2,2-dimethylpropyl, n-hexyl, isohexyl, 2- ethylhexyl, n-heptyl, isoheptyl, n-octyl, isooctyl, n-nonyl, n-decyl and the like.

In the sense of the present invention, the term "C2-C10 alkenyl" includes unsaturated straight or branched hydrocarbon groups containing from two to ten carbon atoms, said hydrocarbon groups having at least one C-C double bond. They include in particular ethenyl, 1-propenyl, 2-propenyl, 1-n-butenyl, 2-n-butenyl, isobutenyl, 1-pentenyl, 1-hexenyl, 1-heptenyl, 1-octenyl, 1-nonenyl, 1-decenyl and the like.

In the sense of the present invention, the term "C ₂ -C ₁₀ alkynyl" includes unsaturated linear or branched hydrocarbon groups containing from two to ten carbon atoms, while these hydrocarbon groups have at least one C-C triple bond. These include in particular ethynyl, 1-propynyl, 2-propynyl, 1-n-butynyl, 2-n-butynyl, isobutynyl, 1-pentynyl, 1-hexynyl, 1-heptynyl, 1-octynyl, 1-noninyl, 1-decynyl and the like.

In the sense of the present invention, the term "C ₃ -C ₁₀ cycloalkyl" includes cyclic, saturated hydrocarbon groups containing from three to ten carbon atoms. They include, in particular, cyclopropyl, cyclobutyl, cyclopentyl, cyclohexyl, cycloheptyl, cyclohexyl, cyclononyl and cyclodecyl.

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

In the sense of the present invention, the term "C ₅ -C ₁₄ heteroaryl" includes aromatic hydrocarbon groups containing from five to fourteen ring hydrocarbon atoms, in which at least one hydrocarbon atom is replaced by a nitrogen, oxygen or sulfur atom. They include, in particular, pyrrolyl, furanyl, thiophenyl, pyrridinyl, pyranyl, thiopyranil and the like. Each of all of the above hydrocarbon groups mentioned above is linked to the central atom according to formula (I) via an oxygen atom.

A battery cell containing such an electrolyte has an advantage over battery cells containing electrolytes known from the prior art in that said first conductive salt contained therein has a higher resistance to oxidation and, therefore, practically does not decompose at more high element voltages. Said electrolyte is oxidation resistant, preferably at least up to an upper potential of 4.0 V, more preferably at least up to an upper potential of 4.2 V, more preferably at least up to an upper potential of 4.4 V, more preferably at least up to an upper potential of 4.6 V, more preferably at least up to an upper potential of 4.8 V, and most preferably at least up to an upper potential of 5.0 V. Thus, at when such an electrolyte is used in a battery cell, there is little or no electrolyte decomposition within operating potentials, that is, in the range between the end-of-charge voltage and the end-of-discharge voltage of both battery cell electrodes. As a result, the battery cells, for example, may have a voltage at the end of charge of at least 4.0 V, more preferably at least 4.4 V, more preferably at least 4.8 V, more preferably at least 5.2 V or more. preferably at least 5.6 volts and most preferably at least 6.0 volts.

The life of a battery cell containing this electrolyte is significantly longer than the life of a battery cell containing electrolytes known in the prior art.

Moreover, a battery cell containing such an electrolyte is also stable at low temperatures. At -40°C, for example, 61% of the charged capacity can still be discharged. The electrical conductivity of the electrolyte at low temperatures is sufficient for the operation of the battery cell.

Moreover, a battery cell containing such an electrolyte exhibits improved stability with respect to residual water. If small residual amounts of water remain in said electrolyte (in the ppm range), said electrolyte or said first conductive salt forms hydrolysis products with water which, compared to the prior art SO ₂ based electrolyte, are significantly less aggressive towards element components. Because of this, the absence of water in said electrolyte plays a less important role in electrolytes based on SO ₂ compared to those known from the prior art. These advantages of the electrolyte according to the present invention outweigh the disadvantage that arises from the fact that said first conductive salt according to formula (I) has a significantly larger anion size than the prior art conductive salt. This higher anion size results in a lower conductivity of said first conductive salt according to formula (I) compared to that of LiAlCl ₄ .

positive electrode

The advantages of using a battery cell according to the present invention with respect to said positive electrode are described below.

Said positive electrode contains at least one compound in the form of an oxide layer as an active material. Said active material can store active metal ions and release and absorb active metal ions during battery cell operation.

In a first advantageous development of a battery cell according to the present invention, said compound has the composition A _x M' _y M'' _z O _a . In this composition, A _x M' _y M'' _z O _a

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

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

- M'' represents at least one element selected from the group consisting of transition metals of groups 4, 5, 6, 7, 8, 9, 10 and 11 of the periodic

Tables of elements;

- x and y independently of each other are integers greater than 0;

- z is an integer greater than or equal to 0; and

- a is an integer greater than 0.

A is preferably lithium metal, that is, said compound may have the composition Li _x M' _y M'' _z O _a .

These oxide layers are oxides of the α-NaFeO ₂ structural type. Oxygen atoms occupy the sites of a face-centered cubic lattice (the so-called fcc lattice); metal ions A and metal cations M' and M'' occupy the existing octahedral holes. In the structure constructed in this way, there is an ordering/separation of lithium and transition metals on alternating layers along the cubic direction [111]. If an excess of metal ions A is used, they can be integrated into the layer of metal cations M' and M''.

The subscripts y and z in the composition A _x M' _y M'' _z O _a refer to the total amount of metals and elements that are represented by M' and M'', respectively. If, for example, M' contains two metals M' ¹ and M' ² , the following applies to the index y: y=y1+y2, with y1 and y2 representing the indices of the metals M' ¹ and M' ² . These numbers or indexes x, y, z and a must be chosen so that charge neutrality is present within the composition.

Examples of compounds in which M' contains two metals are oxides of lithium nickel manganese cobalt composition Li _x Ni _y1 Mn _y2 Co _z O ₂ c M ^'1 =Ni M' ² =Mn and M''=Co. Examples of compounds in which z=0, that is, in which there is no other metal or element M'', are oxides of lithium cobalt Li _x CO _y O _a .

An advantageous development of the battery cell according to the present invention provides that A is lithium and M' is cobalt, with x and y being preferably 1, z being 0 and a preferably being 2. Preferred compounds of the formula Li _x Co _y O _a , are oxides of lithium cobalt. Said LiCoO ₂ compound is an example of lithium cobalt oxide.

A further advantageous development of the battery cell according to the present invention provides that M' is nickel and manganese metals and M'' is cobalt. In the formula Li _x Ni _y1 Mn _y2 Co _z O _a , x, y1 and y2 are, independently of each other, integers greater than 0, z is an integer greater than or equal to 0, and a is an integer greater than 0. The composition of the formula Li _x Ni _y1 Mn _y2 Co _z O ₂ (NMC), that is, lithium nickel manganese cobalt oxide, can be used. Examples of these lithium nickel manganese cobalt oxides are LiNi _1/3 Mn _1/3 Co _1/3 O ₂ (NMC111), LiNi _0.6 Mn _0.2 Co ₂ O ₂ (NMC622) and LiNi _0.8 Mn _{0, 1} Co _0.1 O ₂ (NMC811). Other lithium oxide compounds nickel manganese cobalt oxide may have the composition LiNi _0.5 Mn _0.3 Co _0.2 O ₂ , LiNi _0.5 Mn _0.25 Co _0.25 O ₂ , LiNi _0.52 Mn _0.32 Co _0.16 O ₂ , LiNi _0.55 Mn _0.30 Co _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 O ₂ , LiNi _0.72 Mn _0.10 Co _0.18 O ₂ , LiNi _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 a combination thereof. Battery cell electrodes having cell voltages above 4.6 volts, for example, can be manufactured using these compounds.

A further advantageous development of the battery cell according to the present invention provides that said active material is a metal oxide that is enriched in lithium and manganese (lithium manganese oxide enriched material). These materials can be described by the following formula: Li _x Mn _y M'' _z O _a . M' of the formula Li _x M' _y M'' _z O _a described above thus represents the metal manganese (Mn). M'' is, as defined above, at least one element selected from the group consisting of transition metals of groups 4, 5, 6, 7, 8, 9, 10 and 11 of the Periodic Table of the Elements. Index x is greater than or equal to 1, index y is greater than index z or greater than the sum of indices z1+z2+z3, and so on. For example, if M'' contains 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 with M'' ¹ =Ni z1=0.175 and M'' ² =Co z2=0,1), the following rule applies for index y: y>z1+z2, index z is greater than or equal to 0 and index a is greater than 0. Indices x, y, z and a must be chosen so that charge neutrality is present within the composition. Metal oxides that are enriched in lithium and manganese can also be described by the formula mLi ₂ MnO ₃ ⋅(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 , Li _1.2 Ni _0.13 Co _0.13 Mn _{0, 54} O ₂ or Li _1.16 Mn _0.61 Ni _0.15 Co _0.16 O ₂ .

Within the scope of the present invention, said positive electrode contains at least one of the described layered oxide compounds or combinations of layered oxide compounds as an active material. The combination of layered oxide compounds refers to a positive electrode that contains at least two of the described materials.

Also within the scope of the present invention, said positive electrode comprises as an active material a combination of at least one of the layered oxide compounds described above and at least one other compound that is not a layered oxide compound. Said combination may also include a plurality of layered oxide compounds as described above and/or a plurality of additional compounds that are not layered oxide compounds. Said additional compound may, for example, be a polyanionic compound such as lithium manganese iron phosphate.

A further advantageous development of the battery cell according to the present invention provides that said positive electrode has a discharge cell. This means that said positive electrode also contains a discharge element in addition to said active material. Said bit element serves to provide the necessary electrically conductive connection of said active material of said positive electrode. To do this, the discharge element is in contact with the active material involved in the electrode reaction of the specified positive electrode.

Said bit element can be made flat in the form of a thin metal sheet or thin metal foil. The thin metal foil preferably has a perforated or mesh structure. The flat discharge element may also consist of a metal-coated plastic film. These metal coatings have a thickness in the range from 0.1 µm to 20 µm. Said active material of said positive electrode is preferably applied to the surface of a thin metal sheet, a thin metal foil or a metal-coated plastic foil. Said active material may be applied to the front and/or back of the flat discharge element. Such flat discharge elements have a thickness in the range of 5 µm to 50 µm. The preferred thickness of the flat discharge element is in the range of 10 µm to 30 µm. When using a planar discharge element, said positive electrode may have a total thickness of at least 20 µm, preferably at least 40 µm, and particularly preferably at least 60 µm. The maximum thickness is at most 200 µm, preferably at most 150 µm and particularly preferably at most 100 µm. The specific capacity, based on coating on one side, is at least 0.5 mAh/cm ² when using a flat discharge element, with the following values in this order now preferred: 1 mAh/cm ² . 3 mAh/cm ² .5 mAh/cm ² , 10 mAh/cm ² , 15 mAh/cm ² , 20 mAh/cm ² .

Moreover, it is possible that the positive electrode discharge element is also designed in three-dimensional form as a porous metal structure, in particular as a metal foam. The three-dimensional porous structure of the metal is sufficiently porous that the positive electrode active material can be embedded in the pores of the metal structure. The amount of embedded or deposited active material is the loading of said positive electrode. When the discharge element is designed three-dimensionally in the form of a porous metal structure, in particular in the form of a metal foam, then said positive electrode preferably has a thickness of at least 0.2 mm, more preferably at least 0.3 mm, more preferably at least 0.4 mm. mm, more preferably at least 0.5 mm and most preferably at least 0.6 mm. A further preferred embodiment provides that the specific capacity of said positive electrode when using a three-dimensional element, in particular in the form of a metal foam, is at least 2.5 mAh/cm ² , with 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 . When the discharge element is designed three-dimensionally in the form of a porous metal structure, in particular in the form of a metal foam, the amount of active material of said positive electrode, that is, the specific electrode loading is at least 10 mg/cm ² , preferably at least 20 mg/cm ² , more preferably at least 40 mg/cm ² , more preferably at least 60 mg/cm ² , more preferably at least 80 mg/cm ² , and most preferably at least 100 mg/cm ² . This loading of the positive electrode has a positive effect on the process of charging and discharging the battery cell.

In a further advantageous development of the battery cell according to the present invention, said positive electrode has at least one bond. Said binder is preferably a fluorinated binder, in particular polyvinylidene fluoride and/or a terpolymer which is formed from tetrafluoroethylene, hexafluoropropylene and vinylidene fluoride. However, it can also be a binder that consists of a polymer that consists of monomeric units of a conjugated carboxylic acid or an alkaline, alkaline earth or ammonium salt of that conjugated carboxylic acid, or combinations thereof. Moreover, said binder may also consist of a polymer based on structural units of monomeric styrene and butadiene. In addition, the binder may also be a binder from the group of carboxymethylcelluloses. The binder is present in the specified positive electrode, preferably in a concentration of not more than 20 wt. %, more preferably not more than 15 wt. %, more preferably not more than 10 wt. %, more preferably not more than 7 wt. %, more preferably a maximum of 5 wt. % and most preferably 2 wt. % based on the total weight of the positive electrode.

Electrolyte

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

In a further preferred embodiment of the battery cell, said substituents R ¹ , R ² , R ³ and R ⁴ of said first conductive 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 SO ₂ based electrolyte, 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, t-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 based 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 C double bond -FROM. 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 C triple bond -FROM. They include in particular ethynyl, 1-propynyl, 2-propynyl, 1-n-butynyl, 2-n-butynyl, 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 based electrolyte, the term "C ₃ -C ₆ cycloalkyl" 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 heteroaryl" includes phenyl and naphthyl.

To improve the solubility of said first conductive salt in SO ₂ based electrolytes, said R ¹ , R ² , R ³ and R ⁴ substituents are substituted in a further preferred embodiment of the battery cell with at least one fluorine atom and/or at least one chemical group, said chemical group being selected from the group consisting of C ₁ -C ₄ alkyl, C ₂ -C ₄ alkenyl, C ₂ -C ₄ alkynyl, phenyl and benzyl. Said chemical groups C ₁ -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 hydrocarbon groups described above. Substituted in this context means that individual atoms or groups of atoms of the indicated substituents R ¹ , R ² , R ³ and R ⁴ are replaced by a fluorine atom and/or a specified chemical group.

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

In a further advantageous development of the battery cell, said first conductive salt is selected from the group consisting of

In order to adjust the conductivity and/or other properties of said electrolyte to a desired value, said electrolyte in a further preferred embodiment of the battery cell of the present invention contains at least one second conductive salt different from said first conductive salt according to formula (I). This means that, in addition to said first conductive salt, said electrolyte may contain another second conductive salt that differs from said first conductive salt in its chemical composition and in its chemical structure.

In a further preferred embodiment of the battery cell according to the present invention, said second conductive salt is an alkali metal compound, in particular a lithium compound. Said alkali metal compound or said lithium compound is selected from the group consisting of aluminate, halide, oxalate, borate, phosphate, arsenate and gallate. Said second conductive salt is preferably lithium tetrahaloaluminate, in particular LiAlCl ₄ .

Moreover, in a further preferred embodiment of the battery cell according to the present invention, said electrolyte contains at least one additive. 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 (bisoxalato)borate, lithium difluoro(oxalato)borate, lithium tetrafluoro(oxalato)phosphate, lithium oxalate, 2-vinylpyridine, 4-vinyl pyridine, cyclic exomethylene carbonates, sulfones, cyclic and acyclic sulfonates, acyclic sulfites, cyclic and acyclic sulfinates, organic esters of inorganic acids, acyclic and cyclic alkanes, while acyclic and cyclic alkanes have a boiling point of at least 36 ° C at pressure 1 atm, aromatic compounds, halogenated cyclic and acyclic sulfonimides, halogenated cyclic and acyclic phosphate esters, halogenated cyclic and acyclic phosphines, halogenated cyclic and acyclic phosphites, halogenated cyclic and acyclic phosphazenes, halogenated cyclic and acyclic cal silylamines, halogenated cyclic and acyclic halogenated esters, halogenated cyclic and acyclic amides, halogenated cyclic and acyclic anhydrides and halogenated organic heterocycles.

In relation to the total weight of the composition of said electrolyte, said electrolyte has the following composition in the further advantageous development of the battery cell:

(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, said electrolyte may contain not only the first conductive salt according to formula (I) and the second conductive salt, but also a plurality of first conductive salts in accordance with formula (I) and a plurality of second conductive salts. In the latter case indicated, the percentages indicated above also include a plurality of first conductive salts and a plurality of second conductive salts. The molar concentration of said first conductive salt is in the range of 0.01 mol/l to 10 mol/l, preferably 0.05 mol/l to 10 mol/l, more preferably 0.1 mol/l to 6 mol/l and most preferably from 0.2 mol/l to 3.5 mol/l, based on the total volume of said electrolyte.

A further advantageous development of the battery cell according to the present invention provides that said electrolyte contains at least 0.1 mol SO ₂ , preferably at least 1 mol SO ₂ , more preferably at least 5 mol SO ₂ , more preferably at least 10 mol SO ₂ and most preferably at least 20 mol SO ₂ per mol of conductive salt. Said electrolyte may also contain very high molar proportions of SO ₂ , with said preferred upper limit being 2600 moles SO ₂ per mole conductive salt and upper limits of 1500, 1000, 500 and 100 moles SO ₂ per mole conductive salt being preferred in this okay. The term "per mole of conductive salt" refers to all conductive salts that are part of the specified electrolyte. Electrolytes based on SO ₂ containing such a concentration ratio between SO ₂ and said conductive salt have the advantage that they can dissolve a greater amount of conductive salt compared to said electrolytes known from the prior art, which are based, for example, on a mixture of organic solvents . In the context of the present invention, it has been found that, oddly enough, an electrolyte containing a relatively low concentration of conductive salt is an advantage, despite the higher vapor pressure associated with it, in particular with regard to its stability over many charge and discharge cycles of the cell. battery. The specified concentration of SO ₂ in the specified electrolyte affects its conductivity. Thus, by selecting the concentration of SO ₂ , the conductivity of said electrolyte can be adjusted according to the intended use of the battery cell operating with this electrolyte.

The total content of SO ₂ and the specified first conductive salt may be more than 50 weight percent (wt.%) from the weight of the specified electrolyte, preferably more than 60 wt. %, more preferably more than 70 wt. %, more preferably more than 80 wt. %, more preferably more than 85 wt. %, more preferably more than 90 wt. %, more preferably more than 95 wt. % or most preferably greater than 99 wt. %.

Said electrolyte may contain at least 5 wt. % SO ₂ in terms of the total amount of the specified electrolyte contained in the specified battery cell, while the values of 20 wt. % SO ₂ , 40 wt. % SO ₂ and 60 wt. % SO ₂ are more preferred. Said electrolyte may also contain up to 95 wt. % SO ₂ , while the maximum values of 80 wt. % SO ₂ and 90 wt. % SO ₂ are preferred in that order.

It is within the scope of the present invention that it is preferable for said electrolyte to contain only a small percentage or even no at least one organic solvent. The ratio of organic solvents in said electrolyte, which is present, for example, in the form of a single solvent or a mixture of multiple solvents, may preferably be at most 50 wt. % by weight of the specified electrolyte. Low ratios no 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. % of said electrolyte are most preferred. More preferably, said electrolyte does not contain organic solvents. Due to the low content of organic solvents or even their complete absence, the specified electrolyte is either hardly combustible or completely non-combustible. This increases the operational safety of a battery cell operating with such an SO ₂ based electrolyte. Said SO ₂ based electrolyte is most preferably substantially free of organic solvents.

In relation to the total weight of the composition of said electrolyte, said electrolyte has the following composition in the further advantageous development of the battery cell:

(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,

(iv) 0 to 10 wt. % additive, and

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

active metal

The advantageous improvements of the battery cell according to the present invention with respect to said active metal are described below:

In a first advantageous development of a battery cell, said active metal is

- an alkali metal, in particular lithium or sodium;

- alkaline earth metal, in particular calcium;

- metal of group 12 of the periodic table, in particular zinc; or

- aluminum.

Negative electrode

The advantageous improvements of the battery cell according to the present invention with respect to said negative electrode are described below:

A further advantageous development of the battery cell according to the present invention provides that said negative electrode is a switch electrode. Said inclusion electrode comprises an inclusion material as said active material in which ions of said active metal can be stored during charging of the battery cell and from which ions of said active metal can be removed during discharging of the battery cell. This means that these processes on the electrodes can occur not only on the surface of the electrode, but also inside the said negative electrode. If, for example, a lithium-based conductive salt is used, then lithium ions can be stored in the inclusion material while the battery cell is charged and can be removed from it during the discharging of the battery cell. Said negative electrode preferably contains carbon as active or inclusion material, in particular carbon in the form of allotropic graphite. However, it is also within the scope of the present invention that the carbon is present in the form of natural graphite (flaked, conveyor or rounded), synthetic graphite (mesophase graphite), graphitized mesocarbon microgranules (MCMB), carbon coated graphite, or amorphous carbon.

In a further advantageous development of the battery cell of the present invention, said negative electrode contains lithium intercalating anode active materials that do not contain carbon, such as lithium titanates (eg Li ₄ Ti ₅ O ₁₂ ).

A further advantageous development of the battery cell according to the present invention provides that said negative electrode contains anode active materials which form an alloy with lithium. These are, for example, lithium storage metals and metal alloys (eg Si, Ge, Sn, SnCo _x C _y , SnSi _x and the like) and lithium storage metal oxides and metal alloys (eg SnO _x , SiO _x , oxide glasses Sn, Si and the like).

In a further advantageous development of the battery cell according to the present invention, said negative electrode contains anode conversion active materials. Said anode conversion active materials can be, for example, transition metal oxides in the form of manganese oxides (MnO _x ), iron oxides (FeO _x ), cobalt oxides (CoO _x ), nickel oxides (NiO _x ), copper oxides (CuO _x ) or metal hydrides in the form of magnesium hydride (MgH ₂ ), titanium hydride (TiH ₂ ), aluminum hydride (AlH ₃ ) and ternary hydrides based on boron, aluminum and magnesium, and the like.

In a further advantageous development of the battery cell according to the present invention, said negative electrode contains a metal, in particular lithium metal.

A further advantageous development of the battery cell according to the present invention provides that said negative electrode is porous, wherein said porosity is preferably at most 50%, more preferably at most 45%, more preferably at most 40%, more preferably at most 35%. , more preferably not more than 30%, more preferably not more than 20%, and most preferably not more than 10%. The porosity is the volume of the cavity relative to the total volume of the electrical negative electrode, the volume of the cavity including so-called pores or cavities. This porosity results in an increase in the internal surface area of the electrical negative electrode. Moreover, porosity reduces the density of the electrical negative electrode and hence its weight. Individual pores of the electrical negative electrode can be completely filled with said electrolyte during operation.

A further advantageous development of the battery cell according to the present invention provides that said negative electrode has a discharge cell. This means that in addition to said active or inclusion material, said negative electrode also contains a discharge element. This discharge element serves to provide the necessary electrically conductive 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 electrode reaction of the specified negative electrode. Said bit element may have a planar design 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 discharge element may also consist of a metal-coated plastic film. These metal coatings have a thickness in the range from 0.1 µm to 20 µm. Said negative electrode active material is preferably applied to the surface of a thin metal sheet, a thin metal foil, or a metal-coated plastic foil. Said active material may be applied to the front and/or back of the flat discharge element. Such flat discharge elements have a thickness in the range of 5 µm to 50 µm. The thickness of the flat discharge element is preferably in the range of 10 µm to 30 µm. When using a flat negative discharge element, the electrical electrode may have an overall thickness of at least 20 µm, preferably at least 40 µm, and most preferably at least 60 µm. The maximum thickness is not more than 200 µm, preferably not more than 150 µm and most preferably 100 µm. The specific capacitance of the electrical negative electrode based on the coating on one side is 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 .

Furthermore, it is also possible for the discharge element to be designed three-dimensionally as a porous metal structure, in particular as a metal foam. The term "three-dimensional porous metal structure" refers to any structure composed of metal that not only extends along the length and width of a planar electrode, like a thin metal sheet or metal foil, but also along its thickness. The three-dimensional porous structure of the metal is sufficiently porous that the negative electrode active material can penetrate into the pores of the metal structure. The amount of active material included or deposited is referred to as the load of said negative electrode. When the discharge element is designed three-dimensionally in the form of a porous metal structure, in particular in the form of a metal foam, the electrical negative electrode has a thickness of at least 0.2 mm, more preferably at least 0.3 mm, more preferably at least 0.4 mm. mm, more preferably at least 0.5 mm and most preferably at least 0.6 mm. In this case, the thickness of the electrode is much larger compared to the negative electrode, as in the case of organic lithium ion cells. A further preferred embodiment provides that the specific capacitance of the electrical negative electrode when using a three-dimensional discharge element, in particular in the form of a metal foam, is at least 2.5 mAh/cm ² , with 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 . When the discharge element is designed three-dimensionally in the form of a porous metal structure, in particular in the form of a metal foam, the amount of active material of said negative electrode, that is, the electrode loading in terms of its area, is at least 10 mg/cm ² , preferably at least at least 20 mg/cm ² , more preferably at least 40 mg/cm ² , more preferably at least 60 mg/cm ² , more preferably at least 80 mg/cm ² and most preferably at least 100 mg/cm ² . This loading of the battery negative electrode has a positive effect on the process of charging and discharging the battery cell.

In a further advantageous development of the battery cell according to the present invention, said negative electrode has at least one bond. Said binder is preferably a fluorinated binder, in particular polyvinylidene fluoride and/or a terpolymer which is formed from tetrafluoroethylene, hexafluoropropylene and vinylidene fluoride. However, it can also be a binder that consists of a polymer that consists of monomeric units of a conjugated carboxylic acid or an alkaline, alkaline earth or ammonium salt of that conjugated carboxylic acid, or combinations thereof. Moreover, the binder may also consist of a polymer based on structural units of monomeric styrene and butadiene. In addition, the binder may also be a binder from the group of carboxymethylcelluloses. The specified binder is present in the specified negative electrode, preferably in a concentration of not more than 20 wt. %, more preferably not more than 15 wt. %, more preferably not more than 10 wt. %, more preferably not more than 7 wt. %, more preferably not more than 5 wt. % and most preferably not more than wt. %, based on the total weight of said negative electrode.

In a further advantageous development of the battery cell according to the present invention, said negative electrode has at least one additional conductive material. The additional conductive material should preferably have low weight, high chemical resistance and high specific surface area. Examples of additional conductive materials are in particular carbon (carbon black, Super P, acetylene black), fibrous carbon (CNT carbon nanotubes, carbon (nano) fibers), fine graphite and graphene (nanosheets).

Battery cell structure

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 case. Here, each positive electrode and negative electrode are electrically separated from each other by separators.

The spacer 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 from unsubstituted polyolefins (eg polypropylene or polyethylene), partially or fully halogenated polyolefins (eg partially or fully fluorine-substituted, in particular PVDF, ETFE, PTFE), ester polymers, polyamide or polysulfones. Spacers that include a combination of organic and inorganic materials are, for example, glass fiber textiles 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), THV (a ternary polymer of tetrafluoroethylene, hexafluoroethylene and vinylidene fluoride), perfluoroalcopolymer (PFA), aminosilane, polypropylene or polyethylene (PE) . The spacer 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 may also be in the form of a release paper.

It is also within the scope of the present invention that the separator can be made in the form of a sheath, with each positive electrode or each negative electrode covered by the sheath. The shell may be formed from a nonwoven material, a membrane, a woven material, a knitted material, an organic material, an inorganic material, or a combination thereof.

The use of a sheath on said positive electrode results in a more uniform migration and distribution of ions in the battery cell. The more uniform the distribution of ions, in particular in said negative electrode, the higher the possible loading of the negative electrode with active material and, as a consequence, the useful capacity of the battery cell. This eliminates the risks associated with uneven loading and subsequent deposition of the active metal. These advantages are particularly effective when said positive battery cell electrode is sheathed.

The dimensions of the surface of the electrodes and the sheath can be matched with each other so that the external dimensions of the electrode sheath and the external dimensions of the electrode without the sheath coincide in at least one dimension.

The surface area of the sheath may be larger than the surface area of the electrode. In this case, the sheath goes beyond the boundaries of the boundary electrode. Thus, the two layers of the shell covering the electrode on both sides can be connected to each other at the edge of the positive electrode by the edge connection.

In a further preferred embodiment of the battery cell of the present invention, said negative electrodes are sheathed while said positive electrodes are unsheathed.

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

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

On FIG. 2 shows an electron microscope image of the 3D porous structure of the metal foam of the first embodiment of FIG. 1 as a detailed view;

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

On FIG. 4 shows in detail the second embodiment of FIG. 3;

On FIG. 5 shows a third embodiment of a battery cell according to the present invention in an exploded view;

On FIG. 6 shows the discharge capacity as a function of the number of cycles of the studied complete cells, which contain LiNi _0.6 Mn _0.2 Co _0.2 O ₂ (NMC622) and LiNi _0.8 Mn _{0 lithium nickel manganese cobalt (NMC) oxide, 1} Co _0.1 O ₂ (NMC811) as said active material of said positive electrode;

On FIG. 7 shows the discharge capacity as a function of the number of cycles of the studied complete cells, which contain lithium cobalt oxide LiCoO ₂ (LCO) as the indicated active material of the indicated positive electrode, while the studied full reference cell is filled with a reference electrolyte, and the studied complete cell is filled with electrolyte 1 from Example 2;

On FIG. 8 shows the discharge capacity as a function of the number of cycles of the investigated complete cells containing LiNi _0.6 Mn _0.2 Co _0.2 O ₂ (NMC622) lithium nickel manganese cobalt (NMC) oxide as the indicated active material of the indicated positive electrode, while the studied complete element of comparison is filled with electrolyte reference, and the studied full element is filled with electrolyte 1 from Example 2;

On FIG. 9 shows the discharge capacity as a function of the number of cycles of the studied complete cell containing metal oxide of the composition Li _1.16 Mn _0.61 Ni _0.15 Co _0.16 O ₂ as the specified active material of the specified positive electrode, while the final charge voltage is 4.8 volts;

On FIG. 10 shows the potential profile in volts [V] as a function of the percentage charge of cycle 1 and cycle 2 of the investigated complete cell containing a metal oxide of the composition Li _1.16 Mn _0.61 Ni _0.15 Co _0.16 O ₂ as the indicated active material. said positive electrode;

On FIG. 11 shows the potential profile in volts [V] of the three complete cells under study, which are filled with electrolytes 1, 3 and 4 from Example 2, when the negative electrode is charged as a function of capacitance, which is related to the theoretical capacitance of the negative electrode, during the formation of a coating layer on the indicated negative electrode;

On FIG. 12 shows the discharge potential profile in volts as a function of percent charge of the three complete cells under study that are filled with electrolytes 1, 3 and 4 of Example 2 and contain lithium nickel manganese cobalt oxide (NMC) as the electrode active material;

On FIG. 13 shows the conductivity in [mS/cm] of the electrolyte 1 of Example 2 as a function of the concentration of compound 1;

On FIG. 14 shows the conductivity in [mS/cm] of the electrolyte 3 of Example 2 as a function of the concentration of compound 3; and

On FIG. 15 shows the conductivity in [mS/cm] of the electrolyte 4 of Example 2 as a function of the concentration of compound 4.

On FIG. 1 shows a first embodiment of a battery cell 2 according to the present invention in cross section. Said battery cell 2 is designed as a prismatic cell and has a housing 1, among other things. Said housing 1 includes a set of electrodes 3 which contains three positive electrodes 4 and four negative electrodes 5. Said positive electrodes 4 and said negative electrodes 5 are located alternately in said electrode set 3. Said housing 1 can, however, also contain more positive electrodes. electrodes 4 and/or negative electrodes 5. In general, it is preferable that the number of negative electrodes 5 is one more than the number of positive electrodes 4. This is due to the fact that the outer ends of the set of electrodes are the electrode surfaces of said negative electrodes 5. Electrodes 4, 5 are connected to the corresponding contacts 9, 10 of the battery cell 2 through the electrode connections 6, 7. The battery cell 2 is filled with an electrolyte based on SO ₂ so that the specified electrolyte penetrates as far as possible into all pores or cavities, in particular inside the electrodes 4, 5 .Indicated electrolyte not shown in Fig. 1. In the present embodiment, said positive electrodes 4 contain an intercalator compound as an active material. This intercalator compound is LiCoO ₂ .

Said electrodes 4, 5 are designed flat in the present embodiment, that is, in the form of layers having a thickness less than their surface area. Each of them is separated from each other by separators 11. Said body 1 of the battery cell 2 is essentially made in the form of a rectangular parallelepiped, while said electrodes 4, 5 and the walls of said housing 1, shown in section, run perpendicular to the plane of the drawing and along essentially straight and flat. However, the battery cell 2 can be designed as a winding-shaped cell, in which said electrodes consist of thin layers wound together with a spacer material. Said separators 11, on the one hand, separate said positive electrode 4 and said negative electrode 5 spatially and electrically and, on the other hand, are permeable to said active metal ions, inter alia. In this way, large electrochemically efficient surfaces are created, which provide a correspondingly high current efficiency.

Said electrodes 4, 5 also have a discharge element which serves to provide the necessary electrically conductive connection of said active material of the respective electrode. The specified discharge element is in contact with the active material involved in the electrode reaction of the corresponding electrode 4, 5 (not shown in Fig. 1). The discharge element is made in the form of a porous metal foam 18. The metal foam 18 is located throughout the entire thickness of said electrodes 4, 5. The said active material of the positive electrode 4 and the said negative electrode 5 enters the pores of the said metal foam 18 so that it fills the pores of the metal foam evenly throughout the entire thickness of the metal structure. These positive electrodes 4 contain a binder to increase mechanical strength. Said binder is a fluoropolymer. Said negative electrodes 5 contain carbon as an active material in a form suitable as an inclusion material for absorption of lithium ions. The structure of said negative electrode 5 is similar to that of said positive electrode 4.

On FIG. 2 is a three-dimensional view of the porous structure of the metal foam 18 of the first embodiment of FIG. 1 obtained with an electron microscope. Based on this scale, it can be seen that the pores P have an average diameter of more than 100 μm, that is, they are relatively large. This metal foam is a metal foam made of nickel.

On FIG. 3 shows a second embodiment of a battery cell 20 according to the present invention in cross section. This second embodiment is different from the first embodiment shown in FIG. 1, in that said set of electrodes comprises a positive electrode 23 and two negative electrodes 22. Each of them is separated from each other by separators 21 and placed in a housing 28. Said positive electrode 23 has a discharge element 26 in the form of a flat metal foil, on both sides on which said active material 24 of said positive electrode 23 is deposited. Said negative electrodes 22 also comprise a discharge element 27 in the form of a flat metal foil, on both sides of which said active material 25 of said negative electrode 22 is deposited. Alternatively, flat electrode edge discharge elements, that is, said electrodes terminating the electrode stack may be coated with active material on only one side. The uncoated side faces the housing 28. Said electrodes 22, 23 are connected to the respective contacts 31, 32 of the battery cell 20 via electrode connectors 29, 30.

On FIG. 4 shows a flat metal foil which serves as the discharge element 26, 27 for said positive electrodes 23 and said negative electrodes 22 in the second embodiment of FIG. 3. This metal foil has a perforated or mesh structure, having a thickness of 20 microns.

On FIG. 5 shows a third embodiment of a battery cell 40 according to the present invention in an exploded view. This third embodiment differs from the two described above in that said positive electrode 44 is wrapped by sheath 13. In this case, the surface area of sheath 13 is larger than that of positive electrode 44, boundary 14 is shown in FIG. 5 dotted line. The two layers 15, 16 of the sheath 13 wrapping said positive electrode 44 on both sides are connected to each other at the peripheral edge of said positive electrode 44 by an edge connection 17. The two negative electrodes 45 are not wrapped. Said electrodes 44 and 45 can be connected by electrode connectors 46 and 47.

Example 1: Preparation of a Reference Electrolyte

The reference electrolyte used in the Examples described below was made by the method described in EP 2954588 B1. First, lithium chloride (LiCl) was dried under vacuum at 120°C for three days (hereinafter referred to as [V4]). Particles of aluminum (Al) were dried under 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 bottle containing a gas outlet. Then this mixture was subjected to staged heat treatment to obtain a molten salt. After cooling, the resulting salt melt was filtered, then cooled to room temperature and finally SO ₂ was added until the desired molar ratio of SO ₂ to LiAlCl ₄ was reached. The reference electrolyte thus obtained had the composition LiAlCl ₄ * x SO ₂ , with x depending on the amount of added SO ₂ .

Example 2: Fabrication of Four Embodiments 1, 2, 3 and 4 SO ₂ Based Electrolyte for a Battery Cell

Four embodiments 1, 2, 3 and 4, an SO ₂ based electrolyte was prepared for the experiments described below (hereinafter referred to as Electrolytes 1, 2, 3 and 4). For this purpose, four different first conductive salts were first prepared according to formula (I) using the preparation methods described in the following documents [V5], [V6] and [V7]:

[V5] I. Krossing, Chem. Eur. J. 2001, 7, 490;

[V6] S.M. Ivanova et al., Chem. Eur. J. 2001, 7, 503;

[V7] Tsujioka et al., J. Electrochem. Soc., 2004, 151, A1418

These four different first conductive salts according to formula (I) are referred to below as compounds 1, 2, 3 and 4. They come from the polyfluoroalkoxyaluminate family and are prepared in hexane according to the following reaction equation starting from LiAlH ₄ and the corresponding alcohol R-OH with R ¹ \u003d R ² \u003d R ³ \u003d R ⁴ .

As a result, compounds 1, 2, 3 and 4 were obtained, shown below using the structural formulas and formulas in expanded form:

First, compounds 1, 2, 3 and 4 were recrystallized for purification. As a result, residues of the LiAlH ₄ product were removed from said first conductive salt, since said product could lead to sparks with possible traces of water present in SO ₂ .

Compounds 1, 2, 3 and 4 were then dissolved in SO ₂ . Compounds 1, 2, 3 and 4 were found to be highly soluble in SO ₂ .

The manufacture of electrolytes 1, 2, 3 and 4 was carried out at low temperature or under pressure in accordance with process steps 1 to 4 listed below:

1) placing the respective connections 1, 2, 3 and 4 in the pressure piston each with a pressure tube,

2) pumping out the injection pistons,

3) liquid SO ₂ inlet and

4) repeat steps 2+3 until the required amount of SO ₂ is added.

The corresponding concentration of compounds 1, 2, 3 and 4 in electrolytes 1, 2, 3 and 4 was 0.6 mol/l (molar concentration in terms of 1 liter of the indicated electrolyte), unless otherwise indicated in the description of the experiment. These experiments, described below, were carried out using electrolytes 1, 2, 3 and 4 and a reference electrolyte.

Example 3: Production of investigated complete elements

The investigated complete cells used in these experiments, described below, are cells of a storage battery containing two negative electrodes and one positive electrode, each separated by a separator. Said positive electrode contained an active material, a conduction mediator and a binder. Said negative electrodes contained graphite as said active material and also a binder. As indicated in these experiments, these negative electrodes may also contain additional conductive material. Said active material of said positive electrode is named in the corresponding experiment. The discharge element of the positive and negative electrodes were made of nickel. Among other things, the aim of the studies was to confirm the use of different active materials for said positive electrode in a battery cell according to the present invention in combination with said electrolyte according to the present invention. Table 3 shows which active materials were tested for the indicated positive electrode and which Upper Potential was used.

Each of the studied complete cells was filled with the specified electrolyte required for the specified experiments, that is, either the reference electrolyte or electrolytes 1, 2, 3 or 4.

For each experiment, several, that is, from two to four identical complete elements under study, were made. The results presented in these experiments are the averages of the measured values obtained for identical test complete elements.

Example 4: Measurement of the studied complete elements

For measurements of the studied complete elements, for example, the discharge capacity was determined depending on the number of cycles. For this purpose, the studied complete cells were charged with a charging current of a certain intensity up to a certain maximum potential. The corresponding Upper Potential was held until the charging current dropped to a certain value. Then, a discharge was carried out with a discharge current of a certain intensity up to a certain discharge potential. This charging method is the so-called I/U charging. This process was repeated depending on the desired number of cycles. The upper potential or discharge potential and the corresponding charge or discharge current intensities are given in the indicated experiments. The value to which the charging current had to fall is also described in the indicated experiments.

The term "upper potential" is used as a synonym for the terms "charging potential", "charging voltage", "final charging voltage" and "upper potential limit". The terms denote the voltage/potential to which a cell or battery is charged using a charger.

The battery was preferably charged at a charge rate of C/2 and at a temperature of 22°C. When charging or discharging 1C, by definition, the nominal capacity of the complete cell under study is charged or discharged in one hour. Charge rate C/2 means 2 hours charging time.

The term "discharge potential" is used as a synonym for the term "low cell voltage". This describes the voltage/potential to which a cell or battery is discharged by a charger.

The battery was preferably discharged at a C/2 current and at a temperature of 22°C.

The discharge capacity is determined by the discharge current and the time until the discharge termination criteria are met. The corresponding Figures show the average discharge capacities as a function of the number of cycles. These average discharge capacities are expressed as a percentage of nominal capacity, often normalized to the maximum capacity that was achieved in the respective study. The nominal capacity was obtained by subtracting from the theoretical capacity of the positive electrode the power consumed in the first cycle to form a coating layer on the negative electrode. This coating layer is formed on the specified negative electrode when the investigated complete cell is first charged. Lithium ions are irreversibly consumed in the formation of the coating layer, so that the corresponding complete cell studied has a lower cyclic capacity available for subsequent cycles.

Experiment 1: Investigation of complete cells containing LiNi _0.6 Mn _0.2 Co _0.2 O ₂ (NMC622) and LiNi _0.8 Mn _0.1 Co _0.1 O ₂ (NMC) lithium oxide nickel manganese cobalt (NMC) NMC811) as active electrode materials.

The experiment was carried out in the study of complete cells in accordance with Example 3 using positive electrodes made of lithium oxide nickel manganese cobalt composition 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) as active electrode materials. Compounds of the NMC composition can be charged in a battery cell containing a suitable electrolyte up to high potentials and then discharged again. The studied complete cells were filled with the electrolyte 1 described in Example 2. Three of the investigated complete cells contained positive electrodes containing the indicated compound NMC622, and one investigated complete cell used NMC811 as an active high voltage cathode material.

To determine the discharge capacities (see Example 4), the studied complete cells were charged with a current of 50 mA up to various upper potentials. The corresponding upper potential was maintained until the charging current dropped to 40 mA. Then there was a discharge with a current of 50 mA up to a discharge potential of 2.5 volts. The upper potential for the three total cells studied with NMC622 was 4.4 volts, 4.6 volts, and 5.0 volts. The upper potential of the investigated full cell NMC811 was 4.6 volts.

On FIG. 6 shows the average values of the discharge capacities of the four studied complete cells as a function of the number of cycles. These average discharge capacities are respectively expressed as a percentage of the rated capacity [% of rated capacity]. The profile of the discharge capacities of the studied complete elements has a uniform, slightly decreasing profile. The decrease in capacitance is somewhat greater for those investigated complete elements that were used at a higher upper potential. Similar experiments using organic lithium-ion cells were carried out in the above publication [V1] from the prior art using NMC cathodes and the specified organic electrolyte LP57, which has a composition of 1 M LiPF ₆ in EC:EMC 3:7. Table 4 contains the results of the comparison of Experiment 1 with the results of the experiment from [V1].

The outstanding properties of the battery cells of the present invention become apparent when compared with the prior art. The NMC (622) cathode material in prior art battery cells shows that in the 300th cycle only 94% discharge capacity at a top potential of 4.4 Volts and only 39% discharge capacity at a top potential of 4.6 Volts. In comparison, the cell of the present invention containing NMC (622) cathode material shows in the 300th cycle 97% discharge capacity at 4.4 volts, 91% discharge capacity at 4.6 volts, and even a value of 84% at very high upper potential of 5.0 volts.

Said NMC (811) cathode material exhibits 66% discharge capacity at 300 cycles at a top potential of 4.4 volts as measured in the prior art. The same material still exhibits a high discharge capacity of 90% in the battery cell of the present invention at an upper potential of 4.6 volts.

Experiment 2: Investigation of complete cells containing lithium cobalt oxide LiCoO ₂ (LCO) as active electrode material

In a further experiment, the two investigated complete cells were produced in accordance with Example 3. Said active material of said positive electrodes (cathodes) consisted of lithium cobalt oxide (LCO).

The first complete cell tested was filled with a reference electrolyte according to Example 1 for this Experiment 2. Said electrolyte had the composition LiAlCl ₄ * 6 SO ₂ . The two studied complete cells were filled with electrolyte 1 described in Example 2. The studied complete cells were examined in cycles as described in Experiment 1 to determine the discharge capacities (see Example 4). The upper potential of the battery cell containing the reference electrolyte was 4.2 volts, and that of the cell according to the present invention was 4.4 volts.

On FIG. Figure 7 shows the average values of the discharge capacities of the two studied complete cells as a function of the number of cycles. These average discharge capacities are respectively expressed as a percentage of nominal capacity [% of nominal capacity]. The discharge capacitance profile of the two studied complete cells demonstrates completely different characteristics.

The discharge capacity of the studied complete cell containing the reference electrolyte begins to increase at the 45th cycle, and then drops steeply from the 55th cycle to a capacity of only 50%, achieved at the 80th cycle. The specified examined complete element is irreversibly damaged. A battery cell that contains a combination of an electrode containing lithium cobalt oxide as the specified active material and a reference electrolyte is not stable at an upper potential of 4.2 volts.

The cell according to the present invention exhibits very stable discharge capacity characteristics. 97% capacity is still achievable at cycle 200. Due to the maintenance of the instrument, a break had to be taken between cycles 125 and 126 in the measurement. The capacity increased by 2% after the interruption, so the discharge capacity profile at this point shows a local maximum.

Experiment 3: Investigation of complete cells containing lithium nickel manganese cobalt (NMC) oxide of composition LiNi _0.6 Mn _0.2 Co _0.2 O ₂ (NMC622) as electrode active material

Experiment 2 was repeated using LiNi _0.6 Mn _0.2 Co _0.2 O ₂ (NMC622) lithium nickel manganese cobalt (NMC) oxide as said active material of said positive electrodes (cathodes). The two complete cells tested were again produced according to Example 3.

The first complete cell examined was filled with a reference electrolyte in accordance with Example 1. Said electrolyte had the composition LiAlCl ₄ * 6 SO ₂ . The two studied complete cells were filled with electrolyte 1 described in Example 2. The studied complete cells were examined in cycles as described in Experiment 1 to determine the discharge capacities (see Example 4). The upper potential of the first studied complete cell containing the reference electrolyte was 4.2 volts, and the second studied complete cell was 4.4 volts.

On FIG. 8 shows the average values of the discharge capacities of these two studied complete cells as a function of the number of cycles. These average discharge capacities are respectively expressed as a percentage of nominal capacity [% of nominal capacity]. Here, too, the profile of the discharge capacities of the two studied complete cells demonstrates completely different characteristics.

The discharge capacity of the first studied complete cell containing the reference electrolyte begins to decline steadily from the 75th cycle after the previous fluctuations. The capacity reaches only 86% at the 130th cycle. The specified first complete element examined is irreversibly damaged. A battery cell that contains a combination of an electrode containing lithium nickel manganese cobalt (NMC) oxide of composition LiNi _0.6 Mn _0.2 Co _0.2 O ₂ (NMC622) as the specified active material and the reference electrolyte is not stable at the upper potential 4.2 volts.

The second complete cell examined exhibits very stable discharge capacity characteristics. A capacity of 97% can still be obtained at the 200th cycle.

Experiment 4: Investigation of complete cells containing a metal oxide of the composition Li _1.16 Mn _0.61 Ni _0.15 Co _0.16 O ₂ as the specified active material of the specified positive electrode

To test the metal oxide enriched in lithium and manganese as the active material of the electrode, the test complete cell was produced in accordance with Example 3. Said active material of the positive electrode (cathode) consisted of a metal oxide of the composition Li _1.16 Mn _0.61 Ni _{0, 15} Co _0.16 O ₂ , which is enriched with lithium and manganese.

Said investigated full cell was filled with electrolyte 1 described in Example 2. To determine the discharge capacities (see Example 4), said investigated complete cell was charged with a current intensity of 100 mA up to an upper potential of 4.8 volts. The corresponding upper potential was maintained until the charging current dropped to 40 mA. Then, the discharge was carried out with a current of intensity of 100 mA up to a discharge potential of 2.0 volts.

On FIG. 9 shows the average values of the discharge capacities of the studied complete cell as a function of the number of cycles. These average discharge capacities are respectively expressed as a percentage of nominal capacity [% of nominal capacity]. This investigated full cell shows very stable characteristics of the discharge capacity. A capacity of 90% can still be obtained at the 100th cycle.

On FIG. 10 shows the potential profile in volts [V] of cycle 1 and cycle 2 of the studied complete cell containing a metal oxide that is enriched in lithium and manganese. The specified metal oxide is activated in the first cycle, which provides a high specific capacity characteristic of this material.

The potential profile is depicted as a function of the charge percentage, i.e. it depends on the maximum charge of the studied complete element. The indicated complete cell was charged with a current of 100 mA up to an upper potential of 4.8 V. The indicated potential was maintained until the charging current dropped to 40 mA. Then, the discharge was carried out with a current of intensity of 100 mA up to a discharge potential of 2.0 volts.

The potential curve in cycle 1 shows a clearly different behavior than the potential curve in cycle 2. This is in view of the structural changes in the material known from the literature. During this process, irreversible material changes occur, so that active lithium ions are lost during activation in the first cycle. Only less than 90% of the lithium ions can be retained back in the lattice.

On FIG. 10 demonstrates that in the second cycle over 90% recapture occurs and the deadweight loss is significantly lower than the loss described in the literature.

In cycle 2, the high stability of the electrolyte potential is most evident, since almost complete intercalation of lithium ions occurs in cycle 2 at an upper final charge voltage of 4.8 V.

Experiment 5: Investigation of complete cells containing LiNi _0.6 Mn _0.2 Co _0.2 O ₂ (NMC622) lithium nickel manganese cobalt (NMC) oxide as active electrode material in combination with Electrolyte 1, Electrolyte 3 and Electrolyte 4 .

Various experiments were carried out to investigate electrolytes 1, 3 and 4 in combination with lithium nickel magnesium cobalt oxide (NMC622) as said active material of said positive electrode. On the one hand, the capacities of the coating layer of electrolytes 1, 3, and 4 were determined, and on the other hand, the discharge capacities of all three electrolytes were determined.

The three complete cells tested were filled with electrolytes 1, 3 and 4 described in Example 2 to determine the indicated capacitance of the coating layer. Said three complete cells studied contained lithium nickel magnesium cobalt oxide (NMC622) as said active material of said positive electrode.

On FIG. 11 shows the potential in volts of the investigated complete cells when said negative electrode is charged as a function of capacitance, which is related to the theoretical capacitance of said negative electrode. The two curves shown show the average results of several experiments in the studied full elements described above. First, the studied complete cells were charged with a current of 15 mA until a capacity of 125 mAh (Q _lad ) was reached. Then the studied complete cells were discharged at a current of 15 mA until a potential of 2.5 volts was reached. The discharge capacity (Q _ent ) was determined.

The % of theoretical capacitance used to form the specified coating layer on the specified negative electrode was calculated according to the following formula:

Coating capacity = (Q _lad (125 mAh) - Q _ent (x mAh)) / Q _NEL

Q _NEL is the theoretical capacitance of said negative electrode. The indicated theoretical capacity was calculated, in the case of graphite, up to a value of 372 mAh/g.

The reported capacitances of the coating layers [in % of the theoretical capacitance of the specified negative electrode] were 7.83% in Electrolyte 1, 17.77% in Electrolyte 4, and 20.02% in Electrolyte 3. electrolytes 3 and 4, the battery cell can function very well using these electrolytes in combination with the ability to use high voltage cathodes up to 5 volts.

For the discharge experiments, three investigated complete cells in accordance with Example 3 were filled with electrolytes 1, 3 and 4 described in Example 2. The studied complete cells contained lithium nickel manganese cobalt (NMC) oxide as the specified active material of the specified positive electrode. To determine the discharge capacities (see Example 4), the studied complete cells were charged with a current of intensity of 15 mA up to a capacity of 125 mAh. Then, the discharge was carried out with a current of intensity of 15 mA up to a discharge potential of 2.5 volts.

On FIG. 12 shows the potential profile during discharge of an over-discharged amount of charge in % [% of maximum charge (discharge)]. All complete cells examined exhibited the flat discharge curve necessary for normal battery cell operation.

Experiment 6: Determination of Conductivities of Electrolytes 1, 3 and 4

To determine the conductivity, Electrolytes 1,3 and 4 were prepared using various concentrations of compounds 1, 3 and 4. The conductivities of these electrolytes were determined using the conductive measurement method for each concentration of the various compounds. After temperature control, the two-electrode sensor was kept touching the solution and measurements were made in the range of 0-50 mS/cm. During measurements, it was noted that the specified sensor can interact with an electrolyte solution containing SO ₂ .

On FIG. 13 shows the conductivity of electrolyte 1 as a function of the indicated concentration of compound 1. The maximum conductivity was observed at a concentration of compound 1 of 0.6 mol/l - 0.7 mol/l, which is about 37.9 mS/cm. As a comparison, prior art organic electrolytes such as LP30 (1 M LiPF ₆ / EC-DMC (1:1 by weight)) only have a conductivity of about 10 mS/cm.

On FIG. 14 (Electrolyte 3) and 15 (Electrolyte 4) show the conductivity values found for various concentrations. For Electrolyte 4, the maximum value of 18 mS/cm is achieved at a conductive salt concentration of 1 mol/L. Electrolyte 3 shows the highest conductivity of 0.5 mS/cm at a conductive salt concentration of 0.6 mol/l. Although Electrolyte 3 exhibits low conductivity, as in Experiment 4, it is entirely possible to charge or discharge the full cell under test.

Experiment 7: Performance at low temperature

Two investigated full cells in accordance with Example 3 were produced to determine the performance of Electrolyte 1 at low temperature compared to the reference electrolyte. One investigated complete cell was filled with a reference electrolyte of the composition LiAlCl ₄ * 6SO ₂ , and the other studied complete cell was filled with Electrolyte 1. The studied complete cell containing the reference electrolyte contained lithium iron phosphate (LEP) as the indicated active material, and the examined complete cell, containing Electrolyte 1 contained lithium nickel magnesium cobalt (NMC) oxide as said active material of said positive electrode. The studied total cells were charged to 3.6 volts (LEP) or 4.4 volts (NMC) at 20° C. and again discharged to 2.5 volts at the respective investigated temperature. The discharge capacity achieved at 20°C was taken as 100%. The discharge temperature was lowered in steps of 10°K. The obtained discharge capacity was reflected in % of the discharge capacity at 20°C. Since the discharge at low temperature is practically independent of the specified active materials used for positive and negative electrodes, the results obtained can be transferred to all combinations of active materials. These results are shown in Table 5.

The tested complete cell containing Electrolyte 1 shows very good performance at low temperatures. At -20°C, 82% capacity was achieved, at -30°C - 73%. Even at -40°C, 61% of the capacity can still be discharged. In contrast, the investigated complete cell containing the reference electrolyte shows a discharge capacity only down to -10°C. At this temperature, only 21% capacity is reached. A cell containing a reference electrolyte does not discharge at lower temperatures.

Claims (58)

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 an electrolyte, wherein said positive electrode (4, 23, 44) contains at least one compound in the form of an oxide layer as an active material, and said electrolyte is based on SO ₂ and contains at least one first conductive salt, which has formula (I)

- M is a metal selected from the group consisting of alkali metals, alkaline earth metals, metals of group 12 of the Periodic Table 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, characterized in that said compound has the composition A _x M' _y M'' _z O _a , while - A represents at least one metal selected from the group consisting of alkali metals, alkaline earth metals, metals of group 12 of the Periodic Table or aluminum, - M' represents at least one metal selected from the group consisting of the following elements: Ti, V, Cr, Mn, Fe, Co, Ni, Cu and Zn; - M'' represents at least one element selected from the group consisting of transition metals of groups 4, 5, 6, 7, 8, 9, 10 and 11 of the Periodic Table of the Elements; - x and y independently of each other are integers greater than 0; - z is an integer greater than or equal to 0; and - a is an integer greater than 0. 3. Battery cell (2, 20, 40) according to claim 2, characterized in that said compound has the composition A _x M' _y M'' _z O _a , wherein A is lithium and M' is cobalt and wherein x and y are preferably equal to 1, z is equal to 0 and a is preferably equal to 2. 4. Battery cell (2, 20, 40) according to claim 2, characterized in that said compound has the composition A _x M' _y M'' _z O _a , wherein A is lithium, M' is nickel and manganese and M" represents cobalt. 5. Battery cell according to claim 4, characterized in that said compound has the composition Li _x Ni _y1 Mn _y2 Co _z O _a , while x, y1 and y2 independently of each other are integers greater than 0 and z represents is an integer greater than or equal to 0 and a is an integer greater than 0. 6. Battery cell (2, 20, 40) according to claim 5, characterized in that said compound has the composition LiNi _0.33 Mn _0.33 Co _0.33 O ₂ , LiNi _0.5 Mn _0.3 Co _{0 ,2} O ₂ , LiNi _0.5 Mn _0.25 Co _0.25 O ₂ , LiNi _0.52 Mn _0.32 Co _0.16 O ₂ , LiNi _0.55 Mn _0.30 Co _0.15 O ₂ , LiNi _0.58 Mn _0.14 Co _0.28 O ₂ , LiNi _0.6 Mn _0.2 Co _0.2 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 O ₂ , LiNi _0.72 Mn _0.10 Co _{0 ,18} O ₂ , LiNi _0.76 Mn _0.14 Co _0.10 O, LiNi _0.8 Mn _0.1 Co _0.1 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 a combination thereof. 7. Battery cell according to claim 2, characterized in that said compound has the composition Li _x Mn _y M'' _z O _a , wherein x is an integer greater than or equal to 1 and y is an integer greater than z. 8. Battery cell (2, 20, 40) according to claim 7, characterized in that said compound has the composition Li _x Mn _y M'' _z O _a , in which M'' is nickel and/or cobalt, with this compound preferably has the composition 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 , Li _1.16 Mn _0.61 Ni _0.15 Co _{0 .16} O ₂ or Li _1.2 Mn _0.54 Ni _0.13 Co _0.13 O. 9. Battery cell (2, 20, 40) according to any one of the preceding claims, characterized in that said substituents R ¹ , R ² , R ³ and R ⁴ of said first conductive 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. 10. Battery cell (2, 20, 40) according to any one of the preceding claims, characterized in that at least one of said substituents R ¹ , R ² , R ³ and R ⁴ of said first conductive salt is substituted by at least one atom fluorine and/or at least one chemical group, said chemical group being selected from the group consisting of C ₁ -C ₄ alkyl, C ₂ -C ₄ alkenyl, C ₂ -C ₄ alkynyl, phenyl and benzyl. 11. Battery cell (2, 20, 40) according to any one of the preceding claims, characterized in that at least one of said substituents R ¹ , R ² , R ³ and R ⁴ of said first conductive salt is a CF ₃ group or group OSO ₂ CF ₃ . 12. Battery cell (2, 20, 40) according to any one of the preceding claims, characterized in that said first conductive salt is selected from the group consisting of

13. Battery cell (2, 20, 40) according to any one of the preceding claims, characterized in that said electrolyte contains at least one second conductive salt different from said first conductive salt of formula (I). 14. Battery cell (2, 20, 40) according to claim 13, characterized in that said second conductive salt of said electrolyte is an alkali metal compound, in particular a lithium compound, which is selected from the group consisting of aluminate, halide, oxalate, borate, phosphate, arsenate and gallate. 15. Battery cell (2, 20, 40) according to claim 13 or 14, characterized in that said second conductive salt of said electrolyte is lithium tetrahaloaluminate, in particular lithium tetrachloroaluminate. 16. Battery cell (2, 20, 40) according to any of the preceding claims, characterized in that said electrolyte contains at least one additive. 17. Battery cell (2, 20, 40) according to claim 16, characterized in that said additive of said electrolyte is selected from the group consisting of vinylene carbonate and its derivatives, vinylethylene carbonate and its derivatives, methylethylene carbonate and its derivatives, lithium (bisoxalato) borate , lithium difluoro(oxalato)borate, lithium tetrafluoro(oxalato)phosphate, lithium oxalate, 2-vinylpyridine, 4-vinylpyridine, cyclic exomethylene carbonates, sulfones, cyclic and acyclic sulfonates, acyclic sulfites, cyclic and acyclic sulfinates, organic esters, inorganic acids , acyclic and cyclic alkanes, while acyclic and cyclic alkanes have a boiling point of at least 36 ° C at a pressure of 1 atm, aromatic compounds, halogenated cyclic and acyclic sulfonimides, halogenated cyclic and acyclic phosphate esters, halogenated cyclic and acyclic phosphines, halogenated cyclic and acyclic phosphites, ha logenated cyclic and acyclic phosphazenes, halogenated cyclic and acyclic silylamines, halogenated cyclic and acyclic halogenated esters, halogenated cyclic and acyclic amides, halogenated cyclic and acyclic anhydrides, and halogenated organic heterocycles. 18. Battery cell (2, 20, 40) according to any one of the preceding claims, characterized in that said electrolyte has the composition: (i) from 5 to 99.4 wt.% sulfur dioxide, (ii) from 0.6 to 95% by weight of said first conductive salt, (iii) from 0 to 25% by weight of said second conductive salt, and (iv) from 0 to 10% by weight of the additive, in terms of the total weight of the composition of the specified electrolyte. 19. Battery cell (2, 20, 40) according to any one of the preceding claims, characterized in that the molar concentration of said first conductive salt is in the range from 0.01 mol/l to 10 mol/l, preferably from 0.05 mol /l to 10 mol/l, more preferably from 0.1 mol/l to 6 mol/l and most preferably from 0.2 mol/l to 3.5 mol/l based on the total volume of said electrolyte. 20. Battery cell (2, 20, 40) according to any one of the preceding claims, characterized in that said electrolyte contains at least 0.1 mol SO ₂ , preferably at least 1 mol SO ₂ , more preferably at least 5 mol SO ₂ , more preferably at least 10 mol SO ₂ and most preferably at least 20 mol SO ₂ per mol of conductive salt. 21. Battery cell (2, 20, 40) according to any of the preceding claims, characterized in that said active metal is: - an alkali metal, in particular lithium or sodium; - alkaline earth metal, in particular calcium; - metal of group 12 of the periodic table, in particular zinc; or - aluminum. 22. Battery cell (2, 20, 40) according to any one of the preceding claims, characterized in that said negative electrode (5, 22, 45) is a switching electrode which preferably contains carbon as said active material, in particular in form of allotropic graphite. 23. Battery cell (2, 20, 40) according to any one of the preceding claims, characterized in that said positive electrode (4, 23, 44) and/or said negative electrode (5, 22, 45) contains a discharge cell (26 , 27), which is preferably made - 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 in the form of a metal foam (18). 24. Battery cell (2, 20, 40) according to any of the preceding claims, characterized in that said positive electrode (4, 23, 44) and/or said negative electrode (5, 22, 45) contains at least one a binder, preferably a fluorinated binder, in particular polyvinylidene fluoride and/or a terpolymer made from tetrafluoroethylene, hexafluoropropylene and vinylidene fluoride, or the binder consists of a polymer which is formed from monomeric structural units of a conjugated carboxylic acid or from an alkaline, alkaline earth or ammonium salt of said conjugated carboxylic acid, or from a combination thereof, or the binder consists of a polymer formed by monomeric styrene and butadiene structural units, or the binder is selected from the group of carboxymethylcelluloses, wherein said binder is preferably present at a concentration of at most 20% by weight, more preferably at most 15% by weight, more preferably at most 10% by weight, more preferably at most 7% by weight, more preferably at most 5% by weight and most preferably not more than wt%, based on the total weight of said positive electrode (4, 23, 44). 25. Battery cell (2, 20, 40) according to any one of the preceding claims, characterized in that said cell contains a plurality of negative electrodes (5, 22, 45) and a plurality of positive electrodes (4, 23, 44) located alternately in said housing (1, 28), wherein said positive electrodes (4, 23, 44) and said negative electrodes (5, 22, 45), preferably each, are electrically separated from each other by separators (11, 21, 13).

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