Electrochemical cell and a vehicle incorporating the electrochemical cell

Abstract

The invention relates to an electrochemical cell having at least one positive electrode; at least one negative electrode; and an electrolyte composition which is in contact with the positive electrode and the negative electrode; wherein the positive electrode is produced by a solvent-free method; and the electrolyte composition comprises sulfur dioxide and at least one conducting salt. The present invention further relates to a vehicle incorporating the electrochemical cell.

Description

[0001] 23-1237 WO –1– Electrochemical cell and a vehicle comprising the electrochemical cell The present invention relates to an electrochemical cell and a vehicle comprising the electrochemical cell. Electrochemical cells are of great importance in many technical fields. In particular, electrochemical cells are frequently used for applications in which low voltages are required, such as for the operation of laptops or mobile phones. One advantage of electrochemical cells is that many individual cells can be connected together. For example, cells can provide a high voltage by being connected in series, while a parallel connection of the cells results in a high nominal capacity. Such connections result in batteries with higher energy.Such battery systems are also suitable for high-voltage applications 20 and can, for example, enable the electric propulsion of vehicles or be used for stationary energy storage. In the following, the term "electrochemical cell" is used synonymously for all prior art 25 terms for rechargeable galvanic elements, such as cell, battery, battery cell, accumulator, battery accumulator, and secondary battery. An electrochemical cell is capable of providing electrons to an external circuit during the 30 discharge process. Conversely, an electrochemical cell can be charged during the charging process by means of an external circuit through the supply of electrons. An electrochemical cell has at least two different electrodes, a positive electrode (cathode) 5 and a negative electrode (anode). Both electrodes are in contact with an electrolyte composition.The most commonly used electrochemical cell is the lithium-ion cell, also called a lithium-ion battery. The electrolyte composition plays a crucial role in the safety and performance of an electrochemical cell. During charging and discharging, this composition ensures charge balance between the cathode and anode. The necessary current flow is achieved through the ion transport of a conducting salt in the electrolyte. For example, in lithium-ion cells, the conducting salt is a lithium conducting salt, and lithium ions serve as the current-carrying ions. According to current technological standards, lithium-ion cells contain an anode and a cathode, for the production of which solvents are used (wet coating). Polymers containing hydrogen and soluble in the commonly used solvent N-methylpyrolidone are used as binders.Furthermore, modern lithium-ion cells contain a liquid electrolyte consisting of organic solvents and a suitable conducting salt (usually LiPF6). Without exception, the solvents used for the electrolyte contain a certain proportion of hydrogen. Organic compounds containing hydrogen on their carbon backbone can react with the cell's positive electrode. For example, the positively charged active material can abstract a hydrogen atom from an organic molecule, creating a radical molecule that can then react with other organic molecules (domino effect). This effect is more pronounced the more positive the potential and the higher the temperature of the positive electrode. Consequently, the battery cell ages over time because increasingly larger quantities of organic molecules are destroyed by the described side reaction.The depletion of solvent increases the cell's internal resistance. Furthermore, the binder polymer of the positive electrode is also destroyed over time. This can cause the positive active material to detach from the coating film, and the particles to lose contact with each other. This manifests itself in a further increase in the cell's internal resistance. Therefore, it would be desirable to provide an electrochemical cell with a longer lifespan. That is, it would be desirable to provide an electrochemical cell with reduced calendar and cyclic aging. The object of the invention is to propose a method that avoids or at least reduces some of the disadvantages known in the prior art. This object is achieved according to the invention by means of an electrochemical cell according to the main claim and by means of a motor vehicle according to the dependent claim.30 The subject matter of the main claim relates to an electrochemical cell comprising at least one positive electrode, at least one negative electrode, and an electrolyte composition that is in contact with the positive and negative electrodes. The positive electrode is produced by a solvent-free process 5. Furthermore, the electrolyte composition comprises sulfur dioxide and at least one conducting salt. To improve the aging resistance of lithium-ion cells, it is proposed to use hydrogen-free materials for the cell components that come into direct contact with the positive active material 10 and can degrade through radical aging. More precisely, it is proposed to replace all organic solvents with sulfur dioxide, so that the electrolyte composition 15 is essentially free of organic solvents.In a preferred embodiment, the positive electrode can contain at least one electrochemically active material, at least one fibrillable binder, and optionally a conductive additive. Preferably, the positive electrode can contain at least one electrochemically active material and at least one fibrillable binder. Furthermore, the positive electrode can preferably contain at least one electrochemically active material, at least one fibrillable binder, and a conductive additive. The positive electrode can also comprise more than one electrochemically active material, for example, two, three, four, or more distinct electrochemical materials. The positive electrode can also comprise more than one fibrillable binder, for example, two, three, four, or more distinct binders.An electrochemically active material within the meaning of the invention is a material in which electrical energy is stored in the cell in the form of chemical energy. The electrochemically active material undergoes a chemical reaction during the discharge and charge processes. Such electrochemically active materials are known to those skilled in the art. In a preferred embodiment, the electrochemically active material can be selected from the group consisting of lithium cobalt oxide (LCO), lithium nickel oxide (LNO), lithium nickel cobalt aluminum oxide (NCA), lithium nickel manganese cobalt oxide (NMC), lithium manganese oxide (LMO), lithium iron phosphate (LFP), lithium manganese iron phosphate (LMFP), lithium nickel manganese oxide (LMR), lithium nickel manganese oxide spinel (LNMO), and combinations thereof.20 The fibrillable binder can comprise fluoropolymers, hydrogen-reduced polymers (H-reduced), preferably hydrogen-free polymers (H-free polymers), or mixtures thereof. Fluoropolymers within the meaning of the invention are polymers that 25 are based on carbon compounds with fluorine atoms. In these polymers, usually a large proportion or all of the hydrogen atoms are replaced (substituted) by fluorine. This substitution leads to exceptional resistance to chemical influences and high 30 temperatures. Fluoropolymers are known to those skilled in the art. –6– Fluoropolymers can be, for example, polyvinylidene fluoride (PVDF), copolymers such as poly(vinylidene fluoride-co-hexafluoropropylene) (PVDF-HFP), and polytetrafluoropolyethylene (PTFE). 5 According to a preferred embodiment, the fluoropolymer comprises polytetrafluoropolyethylene (PTFE).A fibrillable binder comprising polytetrafluoropolyethylene can advantageously be processed using a dry coating process 10. We propose PTFE as the binder for the positive electrode, which can also advantageously be processed using a dry coating process. The dry coating process further has the advantage of reducing the machinery required and the amount of solvent used. Hydrogen-reduced polymers according to the invention are high-molecular-weight compounds composed of monomers and containing one or more of elements 20 selected from the group consisting of carbon, nitrogen, oxygen, fluorine, silicon, phosphorus, sulfur, and chlorine.Hydrogen-reduced polymers are high-molecular-weight compounds composed of monomers in which at least some of the hydrogen otherwise present is replaced by elements selected from the group consisting of carbon, nitrogen, oxygen, fluorine, silicon, phosphorus, sulfur, and chlorine. Hydrogen-reduced polymers are known to those skilled in the art. Examples of hydrogen-reduced polymers include perfluoroethylene propylene (FEP), polychlorotrifluoroethylene (PCTFE), polytetrafluoroethylene (PTFE), perfluoroelastomers (FFKM), perfluoropolyethers (PFPE), and polyphosphazenes with hydrogen-free side groups, such as polydichlorophosphazene. According to a preferred embodiment, the hydrogen-reduced polymer comprises polytetrafluoroethylene (PTFE).Hydrogen-free polymers are high-molecular-weight compounds composed of monomers in which all the hydrogen atoms otherwise present are replaced by elements selected from the group consisting of carbon, nitrogen, oxygen, fluorine, silicon, phosphorus, sulfur, and chlorine. Hydrogen-free polymers are known to those skilled in the art. Conductive additives are used to improve electrical conductivity or electrical transport. The conductive additive can be an electrically conductive material known per se. Conductive additives are known to those skilled in the art. According to a preferred embodiment, the conductive additive is selected from the group consisting of conductive carbon black, carbon nanotubes (CNTs), graphene, graphite, and mixtures thereof. Conductive carbon blacks are known to those skilled in the art.Conductive carbon black can, for example, comprise (super)C65, C45, carbon nanotubes, fine-grained conductive graphite, such as SFG6L, or the like. According to a preferred embodiment, the conductive carbon black comprises carbon black C65. –8– The positive electrode can be produced by a generally known solvent-free process. Corresponding solvent-free processes are known to those skilled in the art. For example, such a process is disclosed in US10,547,057 B2. In a preferred embodiment, the positive electrode can be produced by a solvent-free process 10, which comprises the following steps: providing the mixture components comprising electrochemically active material, optionally at least one conductive additive and at least one fibrillable binder; processing the mixture components to produce the coating material 15; and applying the coating material to a carrier film.The fibrillable binder is preferably at least partially fibrillated. The processing of the 20 mixture components to produce the coating material can preferably be carried out in a multi-screw extruder. Advantageously, a continuous mixing process can be realized when using a multi-screw extruder, which, compared to batch mixing processes 25 or semi-continuous processes such as those that can be implemented in a jet mill, enables an increase in productivity as well as a reduction in costs and energy consumption. Furthermore, when using, for example, jet mills, degradation of the 30 electrochemically active components (especially intercalation graphites, but also other materials such as oxides and silicon materials) can occur, since the stress required for the fibrillation of the binder also causes the other components to grind down.The fibrillable binder can enable solvent-free electrode production. It has proven particularly advantageous that the degree of fibrillation can be precisely controlled via the multi-shaft extruder. A number of parameters are available for this purpose, such as the process temperature, throughput, rotational speed, and the configuration of the kneading and / or mixing elements used in the multi-shaft extruder. Following processing in the multi-shaft extruder, the coating material can be in powder form. Such a powder comprises particles, granules, etc. The binder is fibrillated. The particle size of the aforementioned elements can also be conveniently adjusted via the multi-shaft extruder.The powder mixture with the fibrillated binder can be processed into a freestanding electrode film using a roller device (calender) in the first 20-roll gap. This film is then either laminated directly onto a metallic current collector foil (pre-coated / treated or untreated foil made of copper or aluminum, expanded metal, etc.) or first pressed to the desired thickness and density over further rollers (multi-roller mill). Furthermore, by varying the rotational speeds of the rollers in the first gap, subsequent fibril formation and alignment of the fibrils can occur, causing the resulting layer to adhere to the faster-rotating roller and from there be transferred directly onto a current collector foil.–10– The process can include the following steps: - Processing the coating material into a freestanding coating film in a rolling device; - Applying the coating film to the 5 carrier film. The freestanding coating film can be wound up after its production and, if necessary, unwound and used, for example, by applying it to a suitable carrier film, also called a current collector, 10. The coating material, which is in powder form, can be pressed into the freestanding coating film, for example, by a hot rolling system. Subsequent calendering is possible. The freestanding coating film can be rolled up and stored, as mentioned 15. In a next step, the coating film can be laminated onto a current collector film or carrier film. A primer or adhesion promoter can be provided on the current collector or carrier film for this purpose.The primer can be, for example, a polymer (polyvinyl acetate - PVA, carboxymethyl cellulose - CMC, or similar) and, if necessary, a conductive additive (carbon black, carbon nanotubes - CNTs, or similar). The surface of the current collector can also be etched. Alternatively, the process can include the following step: - Forming a coating film directly on or at the carrier film in a rolling device. Advantageously, the forming of the coating film and its application to the carrier film are carried out in the same step. For example, a rolling device can be used to align the (already existing) fibrils in the coating material. Additionally or alternatively, further fibrils can also be generated. This is made possible by operating the rolling device, which comprises several rollers, at different roller speeds.Preferably, the multi-screw extruder is a twin-screw extruder. Kneading elements, or both kneading and mixing elements, are preferably used in the multi-screw extruder or the twin-screw extruder. The shape of the kneading elements significantly influences the mixing process of the mixture components, and in particular the fibril formation. Therefore, the geometry of the kneading elements is an important parameter that influences the production of the coating material. The optimal geometry must generally be determined on a case-by-case basis, as other parameters, such as the aforementioned process temperature, the drive power, and the throughput of the multi-screw extruder, are also crucial, and the parameters interact with each other. The same applies to the mixing elements used and their geometries.For example, the process can include the following step: - Processing the mixture components in a multi-screw extruder at temperatures > 120 °C. 30 Fibrillation of the binder is favored by an elevated temperature, such as a temperature > 120 °C. At higher temperatures, preferably lower shear forces are required for the same extent of fibril formation than at lower temperatures. The use of a multi-screw extruder also enables better heat transfer to the mixture components being mixed. Compared to jet mills, fibrillation can therefore be controlled more precisely and without degradation of the electrochemically active material. Kneading elements, in particular, trigger fibrillation of the binder.Toothed mixing elements (TME elements) can additionally be used to selectively vary the particle size of the resulting granules / particles and to create a particle structure advantageous for dry coating. Preferably, the multi-shaft extruder can include mixing elements and / or kneading elements in addition to conveying elements. The aforementioned TME elements are also referred to in this context as "conveying mixing elements." For example, the process can include the following step: - Preparing, in particular comminuting, the coating material before coating. For example, for possible further adjustment of the particle size, a crusher (mixer, disperser, cutting tool, mill, or similar) can be used after extrusion of the powder mixture. Comminution can be carried out via a system directly connected to the extruder or via an external crusher.For example, the process can include the following step: –13– - Preparing, in particular comminuting, the coating material before coating. For example, for possible further adjustment of the particle size, a crusher (mixer, disperser, cutting tool, mill, or similar) can be used after extrusion of the powder mixture. The comminution can be carried out via a system directly connected to the extruder or an external crusher. 10 Materials and composition of negative electrodes are known to those skilled in the art. The negative electrode can comprise electrochemically active material and optionally at least one conductive additive and 15 fibrillable binder. The electrochemically active material of the negative electrode, i.e., the anode active material, is preferably selected from the group consisting of natural graphite, synthetic graphite, spheroidal graphite, 20 silicon, silicon compounds, and mixtures thereof.The conductive additive present in the negative electrode may preferably be selected from the group consisting of conductive carbon black, carbon nanotubes, graphene, graphite, and mixtures thereof. The fibrillable binder present in the negative electrode may, for example, comprise fluoropolymers, preferably polytetrafluoroethylene, fluorine-free polymers, or mixtures thereof. The negative electrode may preferably be produced by a solvent-free process analogous to the solvent-free process described for the positive electrode. The electrolyte composition comprises sulfur dioxide (SO2) and at least one conducting salt. The stability of the battery cells may be increased by selecting a suitable conducting salt, as well as by selecting a suitable solvent.Sulfur dioxide-based electrolyte compositions exhibit, in particular, increased ionic conductivity, thus enabling the operation of electrochemical cells at high discharge currents without negatively impacting cell stability. Furthermore, sulfur dioxide-based electrolyte compositions are characterized by a high energy density. One disadvantage of sulfur dioxide is its insufficient solubility in many lithium-15 conducting salts that are readily soluble in organic solvents. Therefore, for example, the widely used lithium-15 conducting salt lithium hexafluorophosphate cannot be used in sulfur dioxide-containing electrolyte compositions. By using sulfur dioxide as a solvent, the electrolyte resistance is reduced to approximately 33% compared to conventional lithium-ion cells. This improves the performance of the cells.The reduced heat loss increases the efficiency of the cells, which is particularly advantageous during fast charging. Compared to the prior art, the expected lifespan of the cells is significantly increased (reduced calendar and cyclic aging). A conducting salt within the meaning of the invention is a conducting salt that can be sufficiently dissolved in the electrolyte composition and also has a suitable ionic conductivity to maintain effective charge balance during operation. This increases the stability of an electrochemical cell. All salts that do not contain hydrogen atoms are suitable as conducting salts. This serves to improve the aging resistance of electrochemical cells, such as lithium-ion cells. Preferably, the conducting salt is chemically inert.A chemically inert conducting salt according to the invention is a conducting salt which is chemically inert with respect to all other 10 components of a battery cell, regardless of the state of charge of the battery cell. In a preferred embodiment, the conducting salt has the formula (I), (II) or (II). 15 20. 25 Formula (I) –16– - 4 1 AA 5 m+ 2 sts L Z L 3 2 AA 10 m Formula (II) 15 3 - L 6 5 A 7 AA m 4 20 + ZML 10 8 AA 9 5 AL m 25 Formula (III) Where - M is a metal selected from the group consisting of alkali metals, alkaline earth metals, metals of group 12 of the periodic table of elements and aluminum; - m is 1, 2 or 3; - Z is a central atom selected from the group consisting of elements of groups 2 to 16 of the periodic table, including the lanthanides; 5 - are R 1 to R 4 independently selected from a halogen atom and a chemical group OR 5; - is R 5 selected from the group formed by C1-C 10 Alkyl, C2-C 10 alkenyl, C2-C10 alkynyl, C3-10 C10 cycloalkyl, C6-C14 aryl and C5-C14 heteroaryl; - ask A 1 to A 10 each represents a coordination element that binds to the central atom, where A 1 to A 10 Each is independently selected from the group consisting of elements from groups 15 and 16 of the periodic table; and - represent L 1 to L 5Each independently represents an aliphatic or aromatic bridging residue, wherein the bridging residue forms a five- to eight-membered ring with the central atom Z and with two coordination elements bonded to the central atom Z and the bridging residue, and wherein the ring contains a sequence of 2 to 5 carbon atoms, optionally interrupted by at least one heteroatom. LiAlCl4 is a conducting salt with very high conductivity in SO2. If the voltage limitation of approximately 4V is accepted, hydrogen-free battery cells can be manufactured. This is a basic idea of ​​the present invention.30 The SO2-based electrolyte composition contains SO2 not only as an additive in low concentrations, but in concentrations at which the mobility –18– of the ions of the conducting salt contained in the electrolyte composition, which facilitates charge transport, is at least partially, largely, or even completely ensured by the SO25. The conducting salt is dissolved in the electrolyte composition and exhibits very good solubility therein. It can form a liquid solvate complex with the gaseous SO2, in which the SO2 is bound. In this case, the vapor pressure of the liquid solvate complex is significantly lower than that of pure SO2, resulting in electrolyte compositions with low vapor pressures.However, it is also within the scope of the invention that, depending on the chemical structure of the conducting salt according to one of formulas (I) to (III), a smaller reduction in vapor pressure may occur during the production of the electrolyte composition. In the latter case, it is preferred that the electrolyte composition according to the invention is produced at low temperature or under pressure. The electrolyte composition can also contain several conducting salts of formulas (I) to (III) which differ in their chemical structure. The metal M is selected from the group consisting of alkali metals, alkaline earth metals, metals of group 12 of the periodic table of elements, and aluminum. Alkali metals, alkaline earth metals, metals of group 12 of the periodic table of elements, and aluminum are known to those skilled in the art. Preferably, the metal M is lithium or sodium, and lithium is particularly preferred.–19– The central atom Z is selected from the group consisting of elements of groups 2 to 16 of the periodic table, including the lanthanides. Five elements of groups 2 to 16 of the periodic table, including the lanthanides, are known to those skilled in the art. In a preferred embodiment, the central atom Z is selected from the group consisting of Al, B, Ga, In, P, Ti, Sb, Nb, Zn, Va, Li, P, As, Ta. In a more preferred embodiment, the central atom is selected from the group consisting of Al, B, P, As, Sb, Nb, and Ta. In a particularly preferred embodiment, the central atom is selected from the group consisting of Al, B, P, Sb, and Nb. 1 to R 4 is independently selected from a halogen atom and a chemical group OR 5 In a preferred embodiment, the halogen atom is a chlorine atom. 5 is selected from the group formed by C1-C10 Alkyl, C2-C 10 Alkenyl, C2-C 10 Alkinyl, C3-C 10Cycloalkyl, C6-C14 aryl and C5-C14 heteroaryl. For the purposes of the present invention, the term "C1-C10 alkyl" includes linear or branched saturated hydrocarbon groups with one to ten carbon atoms. These include, in particular, methyl, ethyl, n-propyl, isopropyl, n-butyl, sec-butyl, iso-butyl, tert-butyl, n-pentyl, iso-pentyl, 2,2-dimethylpropyl, n-30 hexyl, iso-hexyl, 2-ethylhexyl, n-heptyl, iso-heptyl, n-octyl, iso-octyl, n-nonyl, n-decyl and the like. –20– For the purposes of the present invention, the term “C2-C10 alkenyl” includes unsaturated linear or branched hydrocarbon groups with two to ten carbon atoms, wherein the hydrocarbon groups 5 have at least one C-C double bond. This includes, in particular, ethenyl, 1-propenyl, 2-propenyl, 1-n-butenyl, 2-n-butenyl, iso-butenyl, 1-pentenyl, 1-hexenyl, 1-heptenyl, 1-octenyl, 1-nonenyl, 1-decenyl and the like.10 The term "C2-C10 alkynyl" encompasses, within the meaning of the present invention, unsaturated linear or branched hydrocarbon groups with two to ten carbon atoms, wherein the 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, iso-butynyl, 1-pentynyl, 1-hexynyl, 1-heptynyl, 1-octynyl, 1-nonynyl, 1-decinyl, and the like. The term "C3-C10 10 "Cycloalkyl" as used in the present invention comprises cyclic, saturated hydrocarbon groups with three to ten carbon atoms. These include, in particular, cyclopropyl, cyclobutyl, cyclopentyl, cycloheptyl, cycloheptyl, cyclohexyl, cycloononyl, and cyclodecanyl. The term "C6-C 14For the purposes of the present invention, "aryl" comprises aromatic hydrocarbon groups with six to fourteen ring-shaped carbon atoms. These include, in particular, phenyl (C6H5 group), naphthyl (C10H7 group) 30 and anthracyl (C 14 H9 group). The term "C5-C14 heteroaryl" encompasses, within the meaning of the present invention, aromatic hydrocarbon groups with five to fourteen ring-shaped hydrocarbon atoms, in which at least one hydrocarbon atom is replaced or exchanged by a nitrogen, oxygen, or sulfur atom. These include, in particular, pyrrolyl, furanyl, thiophenyl, pyrridinyl, pyranyl, thiopyranyl, and the like. In a preferred embodiment, at least one single atom or group of atoms of the substituent R is 510 is substituted by a halogen atom, in particular a fluorine atom, or by a chemical group, wherein the chemical group is selected from the group formed by partially or fully halogenated, in particular fully fluorinated, C1-C4 alkyl, C2-C4 alkenyl, C2-C4 alkynyl, phenyl, benzyl, and wherein the groups C1-C4 alkyl, C2-C4 alkenyl, C2-C4 alkynyl, phenyl, and benzyl may be extended by at least one sulfonyl group. This serves to improve the solubility of the conducting salt in the SO2-based electrolyte composition 20. Extension within the meaning of the invention comprises adding a corresponding group at any possible position as well as substituting (or replacing) an existing group or residue 25 by a corresponding group. If a single atom or group of atoms of the substituent R is 5by a halogen atom, in particular a fluorine atom, or by a chemical group, 30 wherein the chemical group is selected from the group formed by partially or fully halogenated, in particular fully fluorinated, C1-C4 alkyl, C2-C4 alkenyl, C2-C4 alkynyl, phenyl, benzyl, in particular in the case of full fluorination, both the chemical resistance with regard to any oxidation of the cathode that may occur and the electrical conductivity can be increased. The conducting salts of formula (II) and formula (III) have an anion which contains at least one bidentate ligand. For the purposes of the invention, a bidentate ligand is understood to be a molecule which has at least two coordination elements and which binds to a central ion Z via the at least two coordination elements.It would also be conceivable to use other multidentate ligands exhibiting a different dentation, such as tridentate, tetradentate, pentatonic, or hexadentate. Bidentate or multidentate ligands are also generally known as chelating ligands, and the complexes composed of them as chelating complexes. The anion of the salt of formula (II) and formula (III) is thus a chelating complex. The bonds between the chelating ligand and the central ion are difficult to break, which is why the chelating complexes according to the invention are chemically inert to external chemical and physical influences. According to the invention, a chelating complex represents the anion of the at least one salt of formula (II) or (III). Due to these properties, the chelating complexes used according to the invention, in particular the salts composed of them, are both temperature- and hydrolysis-resistant.According to the invention, the described salts dissolve sufficiently in liquid sulfur dioxide, which constitutes the inorganic solvent of the electrolyte composition. Within the scope of the invention, sulfur dioxide is not only included as an additive in low concentrations in the electrolyte composition, but is present in a quantity sufficient to ensure the mobility of the ions of the conducting salt as a solvent. Sulfur dioxide is gaseous at room temperature under atmospheric pressure and forms stable liquid solvate complexes with lithium conducting salts, which exhibit a significantly reduced vapor pressure compared to pure sulfur dioxide. The gaseous sulfur dioxide is thus bound in liquid form and can be handled safely and relatively easily.A particular advantage is the non-flammability of sulfur dioxide 15 itself, as well as of the solvate complexes, which increases the operational reliability of electrolyte compositions based on such solvate complexes and of cells produced using the electrolyte composition. 20 The described salts of formulas (I) to (III) are non-flammable. Therefore, the electrolyte compositions according to the invention are also non-flammable and enable the safe operation of an electrochemical cell comprising the disclosed components of the 25 electrolyte composition. Should sulfur dioxide escape from the cell due to mechanical damage, it cannot ignite outside the cell. Furthermore, the electrolyte composition 30 according to the invention is also cost-effective compared to conventional organic electrolytes.The increased temperature stability and hydrolysis resistance enable direct and almost complete recycling of the electrolyte composition from used batteries without increased effort. For the recycling of used batteries, hydrothermal processes under high pressure and at high temperatures are usually employed. Conventional electrolyte compositions are generally not hydrolysis-resistant and therefore must be processed using other methods. For this purpose, the electrolyte compositions are extracted from batteries in a complex process, for example, by rinsing the cells with supercritical carbon dioxide. In contrast, newer electrolyte formulations based on aluminate, borate, or gallate salts, as described in the prior art, are usually not sufficiently temperature-stable.The electrolyte composition proposed here is temperature-stable and hydrolysis-resistant and can therefore be cost-effectively recycled directly from the electrochemical cells using water-based extraction methods. Due to the water solubility of the proposed components, the electrolyte composition proposed here exhibits high recycling potential with a high recycling rate. Recycling reduces both the primary raw material consumption and the energy required to produce a fresh electrolyte composition, and thus also the carbon dioxide emissions generated during this manufacturing process. Therefore, the manufacturing costs of the electrolyte composition according to the invention and of the electrochemical cell produced using the electrolyte composition can be kept low. The coordination elements A. 1 to A10 bind to the central ion Z and to the bridge remnant, with the 5 coordination elements A 1 to A 10 The coordination elements are each independently selected from the group consisting of elements from groups 15 and 16 of the periodic table. In a preferred embodiment, the at least one coordination element comprises oxygen. In a particularly preferred embodiment, all coordination elements are oxygen. The bidentate chelate ligand has at least two coordination elements and a bridging residue L. 1 to L 5 on, which binds to both coordination elements. 15 L 1 to L 5Each independently represents an aliphatic or aromatic bridging residue. The bridging residue forms a five- to eight-membered ring 20 with the central ion Z and with two coordination elements bonded to the central ion Z and the bridging residue. The ring contains a sequence of 2 to 5 carbon atoms, optionally interrupted by a heteroatom. According to a preferred embodiment of the present invention, the ring contains a continuous 25 sequence of 2 to 5 carbon atoms, preferably 2 to 15 carbon atoms. Another preferred embodiment of the present invention provides that the ring has a sequence of 2 to 5 30 carbon atoms interrupted by a heteroatom. In this case, a heteroatom is preferably embedded in the bridging residue. –26– The heteroatom can, in particular, be oxygen. In other words, the ring or the bridging residue has, in particular, at least one ether group.5. By adding an ether group, the fluorine content of the ring can be reduced. This also reduces the overall fluorine content of the ligand. Although fluorinated compounds exhibit good electrochemical stability, their synthesis is complex and expensive. The fluorine content in the ring, and thus also in the ligand, can be reduced without impairing the electrochemical stability of the ligand by adding heteroatoms to the ring. 15. Ether groups are particularly suitable for this purpose, as they are also stable under oxidative potentials, ensuring electrochemical stability of the ligand despite the reduced fluorine content. However, an excessive number of ether groups can negatively affect the conductivity. 20.Therefore, the number of ether groups should be kept low compared to the number of fluorine groups in order to achieve the desired properties, in particular the desired conductivity. 25 In a preferred embodiment of the present invention, the ring can comprise at least one carbonyl group selected from the group consisting of an imide group, a carboxylic ester group, a carboxylate group, a ketone group, a carboxylic anhydride group, a carbonic ester group, and a carbamate ester group. The presence of at least one carbonyl group advantageously leads to a reduced fluorine content in the ring. –27– This also reduces the overall proportion of fluorine in the ligand. In addition, the carbonyl groups mentioned above also exhibit high electrochemical stability. However, an excessive number of carbonyl groups can negatively affect the conductivity.Therefore, the number of carbonyl groups should be kept low compared to the number of fluorine groups in order to achieve the desired properties, in particular the desired conductivity. In a preferred embodiment of the invention, the bridge residues L. 1 to L 5 Each consists of a linear, branched, or cyclic, saturated hydrocarbon skeleton, optionally fluorine-substituted and / or extended by sulfonyl groups 15. The hydrocarbon skeleton of the bridging residues L 1 to L 5 preferably has 3 to 16 carbon atoms, preferably 5 to 9 carbon atoms. Hydrocarbon skeletons having a carbon skeleton in the aforementioned range yield anions which form particularly stable salts of formula (II) or (III). Examples of a sulfonyl group-extended hydrocarbon skeleton of the bridging residues L 1 to L 5For bidentate ligands, these include, among others, -SO2-(CF2)n-SO2-, -25 [C(CF3)2]-(CF2) m -SO2-(CF2) m -[C(CF3)2]- and -(CF2) m [C(CF3)2]-SO2-. Here, n is 1 to 3 and m is 0 to 2. In a preferred embodiment, the bridge remnants comprise L 1 to L 5 each a hydrocarbon skeleton at least partially fluorinated. 30 In a particularly preferred embodiment, the hydrocarbon skeleton is fully fluorinated. –28– Preferably, the previous embodiments therefore do not contain any hydrogen atoms. Preferably, the anion of the conducting salt has a symmetrical structure. 5 In a preferred embodiment, the conducting salt is LiAlCl4. In a further preferred embodiment, the conducting salt is according to formula (IV). 10 15 20 Formula (IV) Here, the metal M is lithium or sodium, preferably lithium. In a particularly preferred embodiment, the 25 conducting salt is selected from the group consisting of formulas (V)-(VIII). –29– - F3C OO CF3 5 + F3C CF MB 3 F3C CF3 F3C OO CF3 10 Formula (V) - CF3 15 F3C OOOOO + PM 20 F3C O CF O 3 O F3C CF3 O 25 Formula (VI) –30– - CF3 F3C 5 F3C O F3C F3C OO CF3 + Nb MFCO CF3 3 O 10 O F3C CF3 F3 C CF 315 Formula (VII) - CF3 F3C 20 FCO F3C 3 F3C O CF3 + O Sb MFO CF 25 CO 3 3 O F3C CF3 F3 C CF330 Formula (VIII) –31– Here, the metal M is lithium or sodium, preferably lithium. The electrochemical cell can be used in a vehicle. 5 The present invention also relates to a vehicle which has the electrochemical cell according to the invention. The electrochemical cell can function as an electrochemical cell for providing electrical 10 energy for an electric motor of the motor vehicle. The motor vehicle can thus be operated by means of the electrochemical cell according to the invention. That is, the motor vehicle can use the electrochemical cell according to the invention to provide electrical 15 energy for the motor vehicle. Therefore, the electrochemical cell according to the invention can supply electrical components of the motor vehicle with electrical energy.Thus, for example, the vehicle's on-board system and / or other 20 vehicle components and systems can be supplied with electrical energy by the electrochemical cell according to the invention. In particular, the vehicle can be driven at least partially electrically with the electrochemical cell according to the invention. The 25 vehicle can also be driven fully electrically by means of the electrochemical cell according to the invention. Special embodiments 30 [1] Electrochemical cell comprising: - at least one positive electrode; - at least one negative electrode; - an electrolyte composition that is in contact with the positive electrode and the negative electrode; wherein 5 - the positive electrode is produced by a solvent-free process; - the electrolyte composition comprises sulfur dioxide and at least one conducting salt.10 [2] Electrochemical cell according to paragraph [1], wherein the positive electrode comprises at least one electrochemically active material, at least one fibrillable binder, and optionally at least one conductive additive. 15 [3] Electrochemical cell according to paragraph [2], wherein the electrochemically active material is selected from the group consisting of lithium cobalt oxide (LCO), lithium nickel oxide (LNO), lithium nickel cobalt aluminum oxide (NCA), lithium nickel manganese cobalt oxide (NMC), lithium manganese oxide (LMO), lithium iron phosphate (LFP), lithium manganese iron phosphate (LMFP), lithium nickel manganese oxide (LMR), lithium nickel manganese oxide spinel (LNMO), and combinations thereof.25 [4] Electrochemical cell according to paragraph [2], wherein the fibrillable binder comprises fluoropolymers, preferably polytetrafluoroethylene, H-reduced polymers, preferably H-free polymers, or mixtures thereof 30; and / or wherein the conducting additive is selected from the group consisting of conductive carbon black, –33– carbon nanotubes, graphene, graphite and mixtures thereof. [5] Electrochemical cell according to any one of the 5 preceding paragraphs, wherein the conducting salt comprises the following 10 15 20 25 30. Formula (II) 35 or –34– 3 - L 6 5 5 A 7 AA m+ Z 4 ML 10 8 AA 9 10 5 AL m Formula (III) has, where 15 - M is a metal selected from the group consisting of alkali metals, alkaline earth metals, metals of group 12 of the periodic table of elements and aluminium; - m is 1, 2 or 3; 20 - Z signifies a central atom selected from the group consisting of elements of groups 2 to 16 of the periodic table, including the lanthanide group; - R 1 to R 4 25 are selected independently of each other, consisting of a halogen atom and a chemical group OR 5 ; - R 5 selected is from the group formed by C1-C10 alkyl, C2-C10 alkenyl, C2-C10 alkynyl, C3-C 10 Cycloalkyl, C6-C 14 Aryl and C5-C 14 Heteroaryl; 30 - A 1 to A 10 each represents a coordination element that binds to the central atom, where A 1 to A 10Each selected independently of each other –35– are from the group consisting of elements of groups 15 and 16 of the periodic table; and - L 1 to L 5each independently represents an aliphatic or aromatic bridging residue 5, wherein the bridging residue forms a five- to eight-membered ring with the central atom Z and with two coordination elements bonded to the central atom Z and the bridging residue, and wherein the ring contains a sequence of 2 to 5 carbon atoms, optionally interrupted by at least 10 heteroatoms. [6] Electrochemical cell according to paragraph [5], wherein Z is selected from the group consisting of Al, B, Ga, In, P, Ti, Sb, Nb, Zn, Va, Li, P, As, Ta, preferably selected from the group consisting of Al, B, P, As, Sb, Nb and Ta; and / or the at least one coordination element comprises oxygen, preferably that all coordination elements are oxygen.20 [7] Electrochemical cell according to paragraph [5] or [6], wherein the ring contains a continuous sequence of 2 to 5 carbon atoms, preferably 2 to 3 carbon atoms; and / or the ring has a sequence of two to five carbon atoms interrupted by a heteroatom, the heteroatom being preferably oxygen. [8] Electrochemical cell according to any one of paragraphs [5] to [7], wherein the ring comprises at least one carbonyl group selected from the group consisting of an imide group, a carboxylic ester group, a carboxylate group, a carbonic ester group, and a carbamate ester group; and / or L. 1 to L 5independently of one another, each comprises a linear, branched, cyclic, saturated hydrocarbon skeleton, optionally partially fluorinated and / or extended by sulfonyl groups, wherein the hydrocarbon skeleton preferably has 3 to 16 carbon atoms, preferably 5 to 9 carbon atoms, and further preferably that the hydrocarbon skeleton is at least partially fluorinated, and even more preferably that the hydrocarbon skeleton is fully fluorinated. 15 [9] Electrochemical cell according to paragraph [5] or [6], wherein at least one single atom or group of atoms of the substituent R 5is substituted by a halogen atom, in particular a fluorine atom, or by a chemical group, wherein the chemical group 20 is selected from the group formed by partially or fully halogenated, in particular fully fluorinated, C1-C4 alkyl, C2-C4 alkenyl, C2-C4 alkynyl, phenyl, benzyl, and wherein the groups C1-C4 alkyl, C2-C4 alkenyl, C2-C4 alkynyl, phenyl and benzyl may be extended by at least one sulfonyl group 25.

[0010] Electrochemical cell according to any one of paragraphs [5] to [9], wherein the conducting salt is selected from the group consisting of 30–37– - OC(CF3)3 5 + M (F3C)3CO Al OC(CF3)3 OC(CF3)3 10 Formula (IV) - 15 F3C OO CF3 + FC CF M 3 F3C B 3 CF3 FOO 3C CF3 20 Formula (V) 25 30–38– - CF3 F3C 5 OOOOO + PMFCO CF O 3 3 10 O F3C CF3 O 15 Formula (VI)

[0002] –39– - CF3 F3C FCOFC 3 3 5 F3C OO CF3 + Nb MFCO CF3 3 OO 10 F3C CF3 F3 C CF3Formula (VII) 15 - CF3 F3C 20 FCO F3C 3 F3C O CF3 + O Sb MFCO CF 25 O 3 3 O F3C CF3 F3 C CF 330 Formula (VIII) –40– where M = lithium or sodium, preferably lithium.

[0011] Electrochemical cell according to any one of paragraphs [2] to

[0010] , wherein the solvent-free 5 method comprises the following steps: - providing the mixture components comprising electrochemically active material, optionally at least one conductive additive and at least one fibrillable binder; 10 - processing the mixture components to produce the coating material, wherein the fibrillable binder is preferably at least partially fibrillated; and - applying the coating material to a 15 carrier film.

[0012] Vehicle comprising an electrochemical cell according to any one of paragraphs [1] to

[0011] .

Claims

23-1237 WO –41– Claims 1. Electrochemical cell comprising: - at least one positive electrode; 5 - at least one negative electrode; - an electrolyte composition in contact with the positive electrode and the negative electrode; wherein - the positive electrode is produced by a solvent-free 10 process; - the electrolyte composition comprises sulfur dioxide and at least one conducting salt and is free of organic solvent; and - the positive electrode comprises at least one electrochemically 15 active material and a fibrillable binder comprising hydrogen-reduced polymers, preferably hydrogen-free polymers.

2. Electrochemical cell according to claim 1, wherein the 20 positive electrode comprises at least one conducting additive. 3.Electrochemical cell according to claim 2, wherein the electrochemically active material is selected from the group consisting of lithium cobalt oxide (LCO), lithium nickel oxide (LNO), lithium nickel cobalt aluminum oxide (NCA), lithium nickel manganese cobalt oxide (NMC), lithium manganese oxide (LMO), lithium iron phosphate (LFP), lithium manganese iron phosphate (LMFP), lithium nickel manganese oxide (LMR), lithium nickel manganese oxide spinel (LNMO), and combinations thereof.

4. Electrochemical cell according to claim 2, wherein the fibrillable binder is preferably a fluoropolymer. –42– polytetrafluoroethylene or mixtures thereof with H-reduced polymers, preferably H-free polymers; and / or 5 wherein the conducting additive is selected from the group consisting of conductive carbon black, carbon nanotubes, graphene, graphite and mixtures thereof. 10 5. Electrochemical cell according to any one of the preceding claims, wherein the conducting salt comprises the following 15 20 25 Formula (I), 30 –43– the 5 10 or the 15 20 25 formula (III) where - M is a metal selected from the 30 group which is formed by alkali metals, alkaline earth metals, metals of group 12 of the periodic table of elements and aluminium; –44– - m 1, 2 or 3 is; - Z means a central atom, selected from the group consisting of elements of groups 2 to 16 of the periodic table, including group 5 of the lanthanides; - R 1 to R 4 are independently selected from a halogen atom and a chemical group OR 5 ; - R 5 selected from the group formed by C1-C10 alkyl, C2-C10 alkenyl, C2-C10 alkynyl, C3-C10 cycloalkyl, C6-C14 aryl and C5-C14 heteroaryl; - A 1 to A 10 each represents a coordination element that binds to the central atom, where A 1 to A 10Each selected independently, 15 are from the group consisting of elements from groups 15 and 16 of the periodic table; and - L 1 to L 5 each independently represents an aliphatic or aromatic bridging residue, wherein the bridging residue forms a five- to eight-membered ring with the central atom Z and with two coordination elements bonded to the central atom Z and the bridging residue, and wherein the ring contains a sequence of 2 to 5 carbon atoms, optionally interrupted by at least one heteroatom.

6. Electrochemical cell according to claim 5, wherein Z is selected from the group consisting of Al, B, Ga, In, P, Ti, Sb, Nb, Zn, Va, Li, P, As, Ta, preferably selected from the group consisting of Al, B, P, As, Sb, Nb and Ta; and / or the at least one –45– Coordination element oxygen, preferably that all coordination elements are oxygen.

7. Electrochemical cell according to claim 5 or 6, wherein 5 ring contains a continuous sequence of 2 to 5 carbon atoms, preferably 2 to 3 carbon atoms; and / or the ring has a sequence of two to five carbon atoms interrupted by a heteroatom, wherein the heteroatom, 10 preferably is oxygen.

8. Electrochemical cell according to any one of claims 5 to 7, wherein the ring comprises at least one carbonyl group selected from the group consisting of 15 imide group, carboxylic ester group, carboxylate group, carbonic ester group and carbamate ester group; and / or L 1 to L 5independently of one another, each comprises a linear, branched, cyclic, saturated hydrocarbon skeleton, optionally partially fluorinated and / or extended by sulfonyl groups, wherein the hydrocarbon skeleton preferably has 3 to 16 carbon atoms, more preferably 5 to 9 carbon atoms, and more preferably that the hydrocarbon skeleton is at least partially fluorinated, and even more preferably that the hydrocarbon skeleton is fully fluorinated. 30 9. Electrochemical cell according to claim 5 or 6, wherein at least one single atom or group of atoms of the substituent R 5 by a halogen atom, in particular –46– a fluorine atom, or is substituted by a chemical group, wherein the chemical group is selected from the group consisting of partially or fully halogenated, in particular fully fluorinated, C1-C4-5 alkyl, C2-C4 alkenyl, C2-C4 alkynyl, phenyl, benzyl, and wherein the C1-C4 alkyl, C2-C4 alkenyl, C2-C4 alkynyl, phenyl and benzyl groups may be extended by at least one sulfonyl group.

10. Electrochemical cell according to any one of claims 5 to 9, wherein the conducting salt is selected from the group consisting of 15 20 Formula (IV) 25 –47– - F3C O CF3 5 O + FC CF M 3 3 FB 3C CF3 FCOO 3 CF3 10 Formula (V) 15 20 25 30 Formula (VI) –48– - CF3 F3C 5 FOFC 3C 3 F3C OO CF3 + Nb MFCO CF3 3 O 10 O F3C CF3 F3 C CF 315 Formula (VII) - CF3 20 F3C FCO F3C 3 F3C O CF3 + O Sb 25 MFCO CF3 3 OO F3C CF3 F3 C CF 330 Formula (VIII) –49– where M = lithium or sodium, preferably lithium.

11. Electrochemical cell according to any one of claims 52 to 10, wherein the solvent-free method comprises the following steps: - providing the mixture components comprising electrochemically active material, optionally at least one conductive additive and at least one fibrillable binder; - processing the mixture components to produce the coating material, wherein the fibrillable binder is preferably at least partially fibrillated; and - applying the coating material to a carrier film.

12. Vehicle comprising an electrochemical cell according to any one of claims 1 to 11.

Images