Rechargeable Battery Cell

Abstract

The present invention relates to a rechargeable battery cell (20, 40, 101) comprising an SO2-based electrolyte, comprising an active metal, at least one positive electrode (23, 44) having a planar conductor element (26), at least one negative electrode (22, 45) having a planar conductor element (27), a housing (28) and a first conductive salt, wherein the positive electrode (23, 44) and / or the negative electrode (22, 45) comprise at least one first binder comprised of a polymer based on monomeric styrene and butadiene structural units and at least one second binder comprised of carboxymethylcellulose groups.

Description

[Technical Field]

[0001] The present invention relates to a rechargeable battery cell having an SO2-based electrolyte. [Background technology]

[0002] Rechargeable battery cells are of great importance in many technical fields. In many cases, they are used in applications where only small rechargeable battery cells with relatively low currents are needed, such as operating a mobile phone. However, there is also a demand for larger rechargeable battery cells for high-energy applications, and large amounts of stored energy in the form of battery cells are particularly important for electric vehicle drives.

[0003] A key requirement for this type of rechargeable battery cell is a high energy density. This means that the rechargeable battery cell must contain as much electrical energy per unit of weight and volume as possible. For this purpose, lithium has proven to be particularly advantageous as an active metal. The active metal of a rechargeable battery cell refers to a metal whose ions in the electrolyte migrate to the negative or positive electrode during charging and discharging of the cell, where they participate in electrochemical processes. These electrochemical processes directly or indirectly lead to the release of electrons to or the acceptance of electrons from an external circuit. Rechargeable battery cells containing lithium as an active metal are also called lithium-ion batteries. The energy density of such lithium-ion batteries can be increased either by increasing the specific capacity of the electrodes or by increasing the cell voltage.

[0004] Both the positive and negative electrodes of a lithium-ion battery are configured as insertion electrodes. The term "insertion electrode" in the sense of the present invention is understood to mean an electrode having a crystalline structure in which ions of the active material can be stored or released during operation of the lithium-ion battery. This means that electrode processes can occur not only on the surface of the electrode but also within the crystalline structure. During charging of the lithium-ion battery, ions of the active metal are released from the positive electrode and stored in the negative electrode. During discharge of the lithium-ion battery, the reverse process takes place.

[0005] The electrolyte is also an important functional element of a rechargeable battery cell. The electrolyte typically contains a solvent or solvent mixture and at least one conductive salt. For example, a solid electrolyte or ionic solution contains only the conductive salt without the solvent. The electrolyte is in contact with the positive and negative electrodes of the battery cell. At least one ion (anion or cation) of the conductive salt is mobile in the electrolyte, allowing ionic conduction to transport charge between the electrodes, which is necessary for the function of the rechargeable battery cell. The electrolyte undergoes oxidative electrochemical decomposition above a predetermined upper cell voltage limit of the rechargeable battery cell. This process often leads to irreversible destruction of the electrolyte components and ultimately to failure of the rechargeable battery cell. Reductive processes can also destroy the electrolyte below a predetermined lower cell voltage limit. To avoid this process, the positive and negative electrodes are selected so that the cell voltage is less than or greater than the decomposition voltage of the electrolyte. The electrolyte thus determines the voltage window (in English: voltage window) within which the rechargeable battery cell can be operated reversibly, ie repeatedly charged or discharged.

[0006] Lithium-ion batteries known from the prior art contain an electrolyte consisting of an organic solvent or solvent mixture and a conductive salt dissolved therein. The conductive salt is, for example, a lithium salt such as lithium hexafluorophosphate (LiPF6). The solvent mixture may contain, for example, ethylene carbonate. The electrolyte LP57, having a composition of 1M LiPF6 in EC:EMC 3:7, is an example of such an electrolyte. By using the organic solvent or solvent mixture, this type of lithium-ion battery is also called an organic lithium-ion battery.

[0007] In addition to lithium hexafluorophosphate (LiPF), which is frequently used as a conductive salt in the prior art, other conductive salts for organic lithium-ion batteries have been described. For example, Japanese Patent Publication No. 4306858 (hereinafter referred to as [V1]) describes conductive salts in the form of tetraalkoxy salts or tetraaryloxyborate salts, which may be fluorinated or partially fluorinated. JP 2001-143750 A (hereinafter referred to as [V2]) mentions fluorinated or partially fluorinated tetraalkoxyborates and tetraalkoxyaluminates as conductive salts. The conductive salts described in both documents [V1] and [V2] are dissolved in an organic solvent or solvent mixture and used in organic lithium-ion batteries.

[0008] It has long been known that unintentional overcharging of organic lithium-ion batteries leads to irreversible decomposition of electrolyte components. During this process, oxidative decomposition of the organic solvent and / or the conductive salt occurs on the surface of the positive electrode. The reaction heat generated during this decomposition and the gaseous products generated during this process can cause so-called "thermal runaway" and the resulting destruction of the organic lithium-ion battery. Most charging protocols for organic lithium-ion batteries use cell voltage as an indicator of the end of charge. Thermal runaway accidents are particularly likely to occur when using multi-cell battery packs in which multiple organic lithium-ion batteries with different capacities are connected in series.

[0009] Therefore, organic lithium-ion batteries have problems with their own stability and operational safety during long-term use. Safety risks also arise, particularly due to the flammability of the organic solvent or solvent mixture. If an organic lithium-ion battery were to catch fire or even explode, the organic solvent of the electrolyte would form flammable materials. To avoid such safety risks, additional measures must be implemented. These measures include, in particular, extremely precise control of the charging and discharging processes of the organic lithium-ion battery and optimization of the battery structure. Furthermore, organic lithium-ion batteries contain components that melt during an unintended temperature rise, which can fill the organic lithium-ion battery with molten plastic. This prevents further uncontrollable temperature rises. However, these measures increase the manufacturing cost and increase the volume and weight of the organic lithium-ion battery. Furthermore, these measures reduce the energy density of the organic lithium-ion battery.

[0010] A development known from the prior art involves the use of sulfur dioxide (SO2)-based electrolytes in rechargeable battery cells instead of organic electrolytes. Rechargeable battery cells containing SO2-based electrolytes have particularly high ionic conductivity. The term "SO2-based electrolyte" in the context of the present invention is understood to mean an electrolyte that not only contains low concentrations of SO2 as an additive, but also in which the ionic mobility of the conductive salt contained in the electrolyte, responsible for charge transport, is at least partially, predominantly, or even completely ensured by SO2. SO2 thus functions as a solvent for the conductive salt. The conductive salt can form liquid solvate complexes with gaseous SO2, which combine with SO2 and significantly reduce its vapor pressure compared to pure SO2. An electrolyte with a lower vapor pressure is thus produced. This type of SO2-based electrolyte has the advantage of being non-flammable compared to the aforementioned organic electrolytes, thereby eliminating safety risks due to the electrolyte's flammability.

[0011] The selection of binders for the positive and negative electrodes is important for both lithium-ion batteries with organic electrolytes and rechargeable battery cells with SO2-based electrolytes. The binder improves the mechanical and chemical stability of the electrodes. The formation of a surface layer on the negative electrode and the resulting surface capacitance during the first cycle should be minimized to extend the service life of the battery cell. The binder must be stable in the electrolyte used and maintain its stability over the long term, even if the active metal (i.e., lithium in the case of lithium-ion batteries) deposits and comes into contact with the binder during a malfunction that may occur during charge / discharge cycling. Reaction of the binder with the metal can lead to destabilization of the mechanical structure of the electrode. The binder in the electrolyte affects the wettability of the electrode surface. Impaired wettability leads to high resistance within the rechargeable battery cell, resulting in problems during operation of the rechargeable battery cell. An important consideration in the selection of the binder is the shape of the conductor elements. The conductor element can be formed in a planar form, such as a thin metal sheet or foil, or in a three-dimensional porous metal structure, such as a metal foam. The three-dimensional porous metal structure is porous so that the active material of the electrode can be incorporated into the pores of the metal structure. In the case of the planar conductor element, the active material is applied to the front and / or back surface of the planar conductor element. Depending on the shape of the conductor element, different requirements are placed on the binder, such as sufficient adhesion to the conductor element. When selecting the binder and its mass proportion in the electrode, a compromise must often be found between mechanical stability on the one hand and improved electrochemical properties of the electrode on the other hand.

[0012] For example, the authors of the paper "Effects of Styrene Butadiene Rubber / Carboxymethyl Cellulose (SBR / CMC) and Polyvinylidene Difluoride (PVDF) Binders in Low-Temperature Lithium-Ion Batteries" (Jui-Pin Yen, Chia-Chin Chang, Yu-Run Lin, Sen-Thann Shen, and Jin-Long Honga, Journal of the Electrochemical Society, 160 (10) A1811-A1818 (2013)) (hereafter referred to as [V3]) describe an investigation of graphite-based anodes with binders SBR / CMC or PVDF in an organic electrolytic solvent (1 M) containing LiPF6 as the conductive salt in ethylene carbonate (EC) / diethyl carbonate (DEC) (v / v = 1:1). They find that electrodes with PVDF binder have lower resistance, better discharge rate, and better cycling stability than electrodes with SBR / CMC binder mixtures.

[0013] US Patent Application Publication No. 2015 / 0093632 (hereinafter referred to as [V4]) describes an SO2-based electrolyte with the composition LiAlCl4*SO2. The electrolyte preferably contains lithium tetrahaloaluminate, particularly lithium tetrachloroaluminate (LiAlCl4), as a conductive salt. The positive and negative electrodes have conductor elements with exceptionally thick, three-dimensional porous metal structures. To increase the starting capacity and improve the mechanical and chemical stability of the negative and positive electrodes, it is proposed to use a binder A consisting of a polymer of monomeric conjugated carboxylic acid units, such as lithium polyacrylate (LiPAA), or alkali metal, alkaline earth metal, or ammonium salts of the conjugated carboxylic acid, or a combination thereof; a binder B consisting of a polymer based on monomeric styrene and butadiene structural units; or a mixture of binders A and B.

[0014] International Publication No. 2020 / 221564 (hereinafter referred to as [V5]) also discloses an SO2-based electrolyte, particularly containing LiAlCl4 as a conductive salt, in combination with a sulfur-doped active material for the positive electrode. As binders for the negative and positive electrodes, which preferably have conductor elements with a three-dimensional porous metal structure, fluorinated binders such as vinylidene fluoride (THV) or polyvinylidene fluoride (PVDF), polyacrylates such as lithium polyacrylate (LiPAA), binders consisting of polymers based on monomeric styrene and butadiene structural units, or carboxymethylcellulose-based binders are proposed. Polymers of alkaline acids of conjugated carboxylic acids have been found to be particularly useful for the negative electrode. THV and PVDF have been found to be particularly useful for the positive electrode.

[0015] A particular drawback of the SO2-based electrolyte is that if traces of water remain, the resulting hydrolysis products can react with the cell components of the rechargeable battery cell, resulting in the formation of undesirable by-products. Therefore, when manufacturing such rechargeable battery cells using SO2-based electrolytes, care must be taken to minimize the amount of residual water in the electrolyte and cell components.

[0016] A further problem with SO2-based electrolytes is that many conductive salts, especially those known in organic lithium-ion batteries, are insoluble in SO2.

[0017] [Table 1]

[0018] Measurements have shown that SO2 is a poor solvent for many conductive salts, such as lithium fluoride (LiF), lithium bromide (LiBr), lithium sulfate (Li2SO4), lithium bis(oxalato)borate (LiBOB), lithium hexafluoroarsenate (LiAsF6), lithium tetrafluoroborate (LiBF4), lithium trilithium hexafluoroaluminate (Li3AlF6), lithium hexafluoroantimonate (LiSbF6), lithium difluoro(oxalato)borate (LiBF2C2O4), lithium bis(trifluoromethanesulfonyl)imide (LiTFSI), lithium metaborate (LiBO2), lithium aluminate (LiAlO2), lithium triflate (LiCF3SO3), and lithium chlorosulfonate (LiSO3Cl). The solubility of the conductive salts in SO2 is about 10 -2 From 10 -4 mol / L (see Table 1). It can be assumed that at these low salt concentrations, only low conductivity exists at best, insufficient for useful operation of a rechargeable battery cell. [Prior art documents] [Patent documents]

[0019] [Patent Document 1] Patent No. 4306858 [Patent Document 2] Japanese Patent Application Laid-Open No. 2001-143750 [Patent Document 3] US Patent Application Publication No. 2015 / 0093632 [Patent Document 4] International Publication No. 2020 / 221564 [Non-patent literature]

[0020] [Non-Patent Document 1] Jui-Pin Yen, Chia-Chin Chang, Yu-Run Lin, Sen-Thann Shen and Jin-Long Honga, Journal of the Electrochemical Society, 160 (10) A1811-A1818, "Effects of Styrene Butadiene Rubber / Carboxymethyl Cellulose (SBR / CMC) and Polyvinylidene Difluoride (PVDF) Binders on Low-Temperature Lithium-Ion Batteries," 2013 Summary of the Invention [Problem to be solved by the invention]

[0021] In order to further improve the applications and properties of rechargeable battery cells comprising an SO2-based electrolyte, the present invention is based on the task of proposing a rechargeable battery cell with an SO2-based electrolyte which, compared to rechargeable battery cells known from the prior art, has the following: - The electrode has an inert binder, which does not react with the SO2-based electrolyte, is stable at higher charging potentials, does not promote oxidative electrolyte decomposition, and does not inhibit the reaction for surface layer formation. - has a binder that allows the production of electrodes with good mechanical stability, - has a binder that can be uniformly distributed or applied on the conductor element of each electrode together with the active material of the electrode, and that allows good electrical connection of the conductor element of each electrode to the active material; - good wettability between the electrolyte and the electrodes; - The lowest possible prices and high availability, especially for large or widely distributed batteries; - It has a wide electrochemical window so that oxidative electrolyte decomposition does not occur at the positive electrode, - have a stable surface layer on the negative electrode, whereby the surface capacity should be low and no further reductive electrolysis of the negative electrode occurs during subsequent operation; - have an SO2-based electrolyte with good solubility of conductive salts, which makes them good ionic conductors and electronic insulators, thus facilitating ion transport and minimizing self-discharge; - includes an SO2-based electrolyte that is inert to other components in a rechargeable battery cell, such as the separator, electrode materials, and cell casing materials; - Robust against electrical, mechanical or thermal abuse, - Improved electrical performance data, especially high energy density, - Improved overcharge and deep discharge characteristics and lower self-discharge characteristics, and - Longer service life, especially a higher number of usable charge / discharge cycles.

[0022] Such rechargeable battery cells should have, in particular, very good electrical energy and performance data, high operational stability and service life, in particular a high number of usable charge / discharge cycles, without the electrolyte being decomposed during operation of the rechargeable battery cell. [Means for solving the problem]

[0023] This problem is solved by a rechargeable battery cell having the features of claim 1. Claims 2 to 23 describe advantageous developments of the rechargeable battery cell according to the invention.

[0024] The rechargeable battery cell according to the present invention comprises an SO2-based electrolyte containing an active metal, at least one positive electrode having a planar conductor element, at least one negative electrode having a planar conductor element, a housing, and a first conductive salt. The positive electrode and / or the negative electrode contain at least one first binder and at least one second binder. The first binder is composed of a polymer based on monomeric styrene and butadiene structural units. The second binder is selected from a carboxymethyl cellulose group.

[0025] During the development of the battery cell according to the invention, the Applicant encountered many difficult problems associated with the use of an SO2-based electrolyte and planar conductor elements. To distribute the active material, together with the respective binder or binder combination, as uniformly as possible on the planar conductor elements, it was necessary to be able to produce a homogeneous mixture of the components together with the solvent. This homogeneous mixture had to be easily applied onto the planar conductor elements. Failure to meet this requirement would result in significant problems during the production of mechanically stable electrodes. In the case of the rechargeable battery cell according to the invention, this problem was overcome by forming a homogeneous mixture using the active material and the first and second binders, which could then be easily applied onto the planar conductor elements of the respective electrodes. Styrene-butadiene rubber (English: Styrene-butadiene rubber, abbreviated: SBR) can be used as the first binder, and carboxymethylene cellulose (abbreviated: CMC) is particularly used as the second binder.

[0026] The term "conductor element" in the sense of the present invention refers to an electronically conductive element used to enable the required electronically conductive connection of the active material of the respective electrode to an external circuit. For this purpose, said conductor element is in electronic contact with the active material participating in the electrode reaction of said electrode. Said conductor element is present in a planar, i.e. substantially two-dimensional, embodiment.

[0027] The SO2-based electrolyte used in the rechargeable battery cell of the present invention not only contains SO2 as an additive at a low concentration, but also contains SO2 at a concentration such that the ionic mobility of the conductive salt contained in the electrolyte and responsible for charge transport is at least partially, predominantly, or completely ensured by SO2. The first conductive salt is dissolved in the electrolyte and exhibits excellent solubility in the electrolyte. The conductive salt can form a liquid solvate complex with gaseous SO2, and SO2 is bound within the solvate complex. In this case, the vapor pressure of the liquid solvate complex is significantly reduced relative to pure SO2, resulting in an electrolyte with a lower vapor pressure. However, it is within the scope of the present invention that no vapor pressure reduction may occur during the preparation of the electrolyte of the present invention, depending on the chemical structure of the first conductive salt. In the latter case, it is preferable to operate at a low temperature or under pressure during the preparation of the electrolyte of the present invention. The electrolyte may also contain multiple conductive salts with different chemical structures.

[0028] Rechargeable battery cells containing this type of electrolyte have the advantage that the first conductive salt contained in the electrolyte has high oxidative stability, resulting in virtually no decomposition at higher cell voltages. The electrolyte preferably exhibits oxidative stability up to an upper potential of at least 4.0 volts, more preferably up to an upper potential of at least 4.2 volts, even more preferably up to an upper potential of at least 4.4 volts, even more preferably up to an upper potential of at least 4.6 volts, even more preferably up to an upper potential of at least 4.8 volts, and particularly preferably up to an upper potential of at least 5.0 volts. Therefore, when such an electrolyte is used in a rechargeable battery cell, no or very little electrolyte decomposition occurs within the working potential, i.e., the range between the end-of-charge voltage and the end-of-discharge voltage of both electrodes of the rechargeable battery cell. This allows the rechargeable battery cell of the present invention to have an end-of-charge voltage of at least 4.0 volts, more preferably at least 4.4 volts, even more preferably at least 4.8 volts, even more preferably at least 5.2 volts, even more preferably at least 5.6 volts, and particularly preferably at least 6.0 volts. The service life of a rechargeable battery cell containing this electrolyte is significantly increased compared to rechargeable battery cells containing electrolytes known from the prior art.

[0029] Furthermore, rechargeable battery cells containing such electrolytes have low temperature stability: for example, 61% of the charged capacity can still be discharged at a temperature of -40°C. The conductivity of the electrolyte at low temperatures is sufficient to operate the battery cell.

[0030] positive electrode Advantageous developments of the rechargeable battery cell according to the invention with respect to the positive electrode are described below:

[0031] In a first development of the rechargeable battery cell according to the invention, the positive electrode is chargeable to an upper potential limit of at least 4.0 volts, preferably to a potential of 4.4 volts, more preferably to a potential of at least 4.8 volts, even more preferably to a potential of at least 5.2 volts, even more preferably to a potential of at least 5.6 volts and particularly preferably to a potential of at least 6.0 volts.

[0032] In another advantageous development of the rechargeable battery cell according to the invention, the positive electrode comprises at least one active material capable of storing ions of the active metal and releasing and reacquiring the ions during operation of the battery cell. It is important that the binder of the positive electrode does not impede a good electrical connection of the active material to the planar conductor element. The use of the first and second binders ensures a good electrical connection of the active material to the planar conductor element of the positive electrode, which is maintained during operation in the battery.

[0033] In another advantageous development of the rechargeable battery cell according to the invention, the positive electrode comprises at least one intercalation compound. The term "intercalation compound" in the context of the present invention is to be understood as a subcategory of the aforementioned intercalation materials. The intercalation compound functions as a host matrix with interconnected voids into which the ions of the active metal can diffuse and accumulate during the discharge process of the rechargeable battery cell. Little or no structural changes occur in the host matrix during this accumulation of the ions of the active metal.

[0034] In another advantageous development of the rechargeable battery cell according to the invention, the positive electrode comprises at least one conversion compound as the active material. The term "conversion compound" in the sense of the present invention is understood to mean a material which forms other materials during electrochemical activity, i.e., chemical bonds are broken and reformed during charging and discharging of the battery cell. A structural change occurs in the matrix of the conversion compound upon the acceptance and release of the ions of the active metal.

[0035] In another advantageous development of the rechargeable battery cell according to the invention, the active material is x M' y M” z O a The composition A has the following composition. x M' y M” z O a In A is at least one metal selected from the group formed by alkali metals, alkaline earth metals, metals of group 12 of the periodic table of the elements or aluminum; M' is at least one metal selected from the group formed by the elements Ti, V, Cr, Mn, Fe, Co, Ni, Cu and Zn, M" is at least one element selected from the group formed by the elements of groups 2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13, 14, 15 and 16 of the Periodic Table of the Elements, - x and y are independent numbers greater than 0, - z is a number greater than or equal to 0, and - a is a number greater than 0. Preferably, A is metallic lithium, i.e., the compound is Li x M' y M” z O a The composition may be:

[0036] Composition A x M' y M” z O aThe indices y and z are represented by M' and M" respectively and represent the sum of metals and elements. For example, M' is a metal with two M' 1 and M' 2 In the case where the index y is y=y1+y2, y1 and y2 are the metals M' 1 and M' 2 The indices x, y, z, and a must be selected so that the charge in the composition is neutral. An example of a compound where M' contains two metals is M' 1 =Ni, M' 2 Composition Li where M" = Mn and M" = Co x Ni y1 Mn y2 Co z An example of a compound where z=0, i.e., there is no other metal or element M″, is lithium cobalt oxide, Li x Co y O a For example, M" has two elements, one is metal M" 1 and on the other hand M” 2 When the compound contains phosphorus as a metal, then for the index z, z=z1+z2, and z1 and z2 are the metals M" 1 and Lynn (M 2 The indices x, y, z and a must be chosen so that the charge in the composition is neutral. A represents lithium, M" represents the metal M" 1 and M” 2 Examples of compounds containing phosphorus as A are A=Li, M'=Fe, M" 1 =Mn, M” 2 Lithium iron manganese phosphate Li = P and z = 1 x Fe y Mn z1 P z2 O4. In other compositions, M" can be two nonmetals, e.g., M" 1 as fluorine, M” 2 An example of such a compound is lithium iron fluorosulfate Li, where A=Li, M'=Fe, M"1=F and M"2=P. x Fe y F z1S z2 There is O4.

[0037] In another advantageous development of the rechargeable battery cell according to the invention, M' consists of the metals nickel and manganese and M" is cobalt. In this case, x Ni y1 Mn y2 Co z Lithium with a composition of O2(NMC), i.e., a layered oxide structure D Kuckel Ma Ngan Ko Examples of the active material made of such lithium nickel manganese cobalt oxide include LiNi 1 / 3 Mn 1 / 3 Co 1 / 3 O2(NMC111), LiNi 0.6 Mn 0.2 Co 0.2 O2 (NMC622) and LiNi 0.8 Mn 0.1 Co 0.1 O2 (NMC811). Other compounds made of lithium nickel manganese cobalt oxide have the composition LiNi 0.5 Mn 0.3 Co 0.2 O2, LiNi 0.5 Mn 0.25 Co 0.25 O2, LiNi 0.52 Mn 0.32 Co 0.16 O2, LiNi 0.55 Mn 0.30 Co 0.15 O2, LiNi 0.58 Mn 0.14 Co 0.28 O2, LiNi 0.64 Mn 0.18 Co 0.18 O2, LiNi 0.65 Mn 0.27 Co 0.08 O2, LiNi 0.7 Mn 0.2 Co 0.1 O2, LiNi 0.7 Mn 0.15 Co 0.15 O2, LiNi 0.72 Mn0.10 Co 0.18 O2, LiNi 0.76 Mn 0.14 Co 0.10 O2, LiNi 0.86 Mn 0.04 Co 0.10 O2, LiNi 0.90 Mn 0.05 Co 0.05 O2, LiNi 0.95 Mn 0.025 Co 0.025 It may have O2 or combinations thereof. By using this compound, it is possible to manufacture a positive electrode for a rechargeable battery cell having a cell voltage greater than 4.6 volts.

[0038] In another advantageous development aspect of the rechargeable battery cell according to the present invention, the active material is a metal oxide rich in lithium and manganese (in English, an oxide material rich in lithium and manganese). The metal oxide may have the composition Li x Mn y M” z O a Thus, M’ represents metallic manganese manganese (Mn in the above formula Li x M’ y M” z O a Here, the exponent x is 1 or more, and the exponent y is greater than the sum of the exponent z or the exponents z1 + z2 + z3, etc. For example, when M” includes two metals M” 1 and M” 2 (for example, M” 1 = Ni z1 = 0.175 and M” 2 = Co z2 = 0.1 in Li 1.2 Mn 0.525 Ni 0.175 Co 0.1 O2), for the exponent y, y > z1 + z2 applies. The exponent z is 0 or more, and the exponent a is greater than 0. The exponents x, y, z, and a must be selected so that the charge in the composition is neutral. The metal oxide rich in lithium and manganese can also be represented by the formula mLi2MnO3(1 - m)LiM’O2 where 0 < m < 1. An example of this kind of compound is Li 1.2Mn 0.525 Ni 0.175 CO 0.1 O2, Li 1.2 Mn 0.6 Ni 0.2 O2 or Li 1.2 Ni 0.13 CO 0.13 Mn 0.54 It is O2.

[0039] In another advantageous development of the rechargeable battery cell according to the invention, the composition is of the formula A x M' y M” z The compound has a spinel structure. For example, A can be lithium, M' can be cobalt, and M" can be manganese. In this case, the active material is lithium cobalt manganese oxide (LiCoMnO4). LiCoMnO4 can be used to fabricate positive electrodes for rechargeable battery cells with cell voltages greater than 4.6 volts. LiCoMnO4 has Mn 3+ In another example, M' can be nickel and M" can be manganese. In this case, the active material is lithium nickel manganese oxide (LiNiMnO4). The molar ratio of both metals M' and M" can be different. The lithium nickel manganese oxide is, for example, LiNi 0.5 Mn 1.5 It may have a composition of O4.

[0040] In another advantageous development of the rechargeable battery cell according to the invention, the positive electrode comprises at least one active material that is a conversion compound. When the conversion compound accepts an active metal, such as lithium or sodium, a solid-state redox reaction occurs, during which the crystalline structure of the material changes. This occurs under the breaking and reformation of chemical bonds. A fully reversible reaction of the conversion compound can be, for example, as follows: Type A: MX z +yLi ⇔ M+zLi (y / z) X Type B: X+yLi ⇔ Li y X Examples of conversion compounds are FeF2, FeF3, CoF2, CuF2, NiF2, BiF3, FeCl3, FeCl2, CoCl2, NiCl2, CuCl2, AgCl, LiCl, S, Li2S, Se, Li2Se, Te, I and LiI.

[0041] In another advantageous development, the compound is A x M' y M” z1 M” z2 O4, M″ is phosphorus, and the value of z2 is 1. x M' y M” z1 M” z2 Compounds with O4 are the so-called lithium metal phosphates. Such compounds have the composition Li x Fe y Mn z1 P z2 Examples of lithium metal phosphates are lithium iron phosphate (LiFePO4) or lithium iron manganese phosphate (Li(Fe y Mn z )PO4). An example of lithium manganese iron phosphate is Li(Fe 0.3 Mn 0.7 )PO4. An example of lithium iron manganese phosphate is Li(Fe 0.3 Mn 0.7 )PO4. Lithium metal phosphates having other compositions may also be used in the battery cell according to the present invention.

[0042] In another advantageous development of the rechargeable battery cell according to the invention, the positive electrode comprises at least one metal compound selected from the group formed by metal oxides, metal halides and metal phosphates, the metal of which is preferably a transition metal of atomic numbers 22 to 28 of the periodic table of the elements, in particular cobalt, nickel, manganese or iron.

[0043] In another advantageous development of the rechargeable battery cell according to the invention, the positive electrode comprises at least one metal compound having the chemical structure of a spinel, a layered oxide, a conversion compound or a polyanionic compound.

[0044] It is within the scope of the present invention that the positive electrode comprises as an active material at least one of the aforementioned compounds or combinations of compounds, where combinations of compounds refer to positive electrodes comprising at least two of the aforementioned materials.

[0045] The battery cell according to the present invention has a positive electrode having a planar conductor element. This means that the positive electrode contains a conductor element in addition to the active material. The conductor element is used to enable the necessary electronically conductive connection of the active material of the positive electrode. To this end, the conductor element is in contact with the active material participating in the electrode reaction of the positive electrode. The planar conductor element is preferably a thin metal sheet or a thin metal foil. The thin metal foil may have a perforated or mesh structure. The planar conductor element may also consist of a metal-coated plastic foil. The metal coating has a thickness in the range of 0.1 μm to 20 μm. The active material of the positive electrode is preferably applied to the surface of the thin metal sheet, thin metal foil, or metal-coated plastic foil. The active material may be applied to the front and / or back of the planar conductor element. This type of planar conductor element has a thickness in the range of 5 μm to 50 μm. The thickness of the planar conductor element is preferably in the range of 10 μm to 30 μm. When planar conductor elements are used, the total thickness of the positive electrode can be at least 20 μm, preferably at least 40 μm, and particularly preferably at least 60 μm. The maximum thickness is at most 200 μm, preferably at most 150 μm, and particularly preferably at most 100 μm. The area-specific capacitance of the coating on one side of the positive electrode when planar conductor elements are used is preferably at least 0.5 mAh / cm. 2 and the following values ​​in this order are preferred: 1 mAh / cm 2, 3mAh / cm 2 , 5mAh / cm 2 , 10mAh / cm 2 , 15mAh / cm 2 , 20mAh / cm 2 When the conductor element is formed in the form of a planar thin metal sheet, a thin metal foil or a metal-coated plastic foil, the amount of active material in the positive electrode, i.e., the electrode loading in terms of surface coating, is preferably at least 1 mg / cm 2 , preferably at least 3 mg / cm 2 , and more preferably at least 5 mg / cm 2 , and more preferably at least 8 mg / cm 2 , and more preferably at least 10 mg / cm 2 and particularly preferably at least 20 mg / cm 2 is.

[0046] The maximum loading of the electrode for one-sided coating is preferably at most 150 mg / cm 2 , and more preferably at most 100 mg / cm 2 and particularly preferably at most 80 mg / cm 2 is.

[0047] In another advantageous development of the battery cell according to the invention, the positive electrode comprises a further binder different from the first and second binders, said further binder preferably being: fluorinated binders, in particular polyvinylidene fluoride (abbreviated PVDF) and / or terpolymers formed by tetrafluoroethylene, hexafluoropropylene and vinylidene fluoride, or - Polymers consisting of monomeric structural units of conjugated carboxylic acids or alkali metal, alkaline earth metal or ammonium salts of said conjugated carboxylic acids, or combinations thereof.

[0048] The additional binder in the form of a polymer can be lithium polyacrylate (LiPAA). The positive electrode can also have two additional binders different from the first and second binders. In this case, the positive electrode preferably comprises a third binder in the form of a fluorinated binder, in particular polyvinylidene fluoride (PVDF) and / or a terpolymer formed from tetrafluoroethylene, hexafluoropropylene, and vinylidene fluoride, and a fourth binder in the form of a polymer consisting of monomeric structural units of conjugated carboxylic acids or alkali metal, alkaline earth metal, or ammonium salts of such conjugated carboxylic acids, or a combination thereof. The use of fluorinated binders presents a problem in that they are often soluble only in organic solvents, which are highly flammable and harmful to the environment. The production of positive electrodes using fluorinated binders requires the use of complex equipment designed to accommodate the use of such solvents. This raises particular concerns about explosion prevention, environmental protection, and protection of staff from exposure to radiation. This issue was taken into account by the applicant when developing the advantageous development of the battery cell according to the present invention.

[0049] During the development of the rechargeable battery cell of this patent application, the applicant discovered that it was difficult to determine the optimal concentration of the first, second, third, and / or fourth binders relative to the total weight of the positive electrode: if the concentration in the positive electrode is too low, the resulting positive electrode will be difficult to handle. For example, an electrode without a binder will not adhere to the conductive element, resulting in particle shedding of the active material, which may result in the resulting rechargeable battery cell being unusable. A binder concentration that is too high also has a negative impact on the energy density of the rechargeable battery cell, as the energy density decreases with the weight of the binder. Furthermore, a binder concentration that is too high will impair the wettability of the positive electrode with the SO2-based electrolyte. Therefore, the concentration of all binders in the positive electrode is preferably at most 20 wt %, more preferably at most 15 wt %, even more preferably at most 10 wt %, even more preferably at most 7 wt %, even more preferably at most 5 wt %, even more preferably at most 2 wt %, even more preferably at most 1 wt %, and particularly preferably at most 0.5 wt % relative to the total weight of the positive electrode. The concentration of all binders in the positive electrode is preferably in the range of 0.05 wt% to 20 wt%, more preferably in the range of 0.5 wt% to 10 wt%, and especially preferably in the range of 0.5 wt% to 5 wt%. Such concentrations allow for good wettability of the positive electrode with SO2-based electrolytes, good handling of the positive electrode, and good energy density of rechargeable battery cells using such positive electrodes.

[0050] electrolyte In the following, advantageous developments of rechargeable battery cells are described with respect to SO2-based electrolytes.

[0051] In an advantageous development of the rechargeable battery cell according to the invention, the first conductive salt is alkali metal compounds, in particular lithium compounds, selected from the group formed by aluminates, in particular lithium tetrahaloaluminates, halides, oxalates, borates, phosphates, arsenates and gallates, - a conducting salt having the following formula (I), [ka] M is a metal selected from the group formed by 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; - Substituent R 1 , R 2 , R 3 and R 4 are C1 to C 10 Alkyl, C2-C 10 Alkenyl, C2-C 10 Alkynyl, C3-C 10 Cycloalkyl, C6-C 14 Aryl and C5-C 14 heteroaryl, and - The central atom Z is aluminum or boron.

[0052] "C1-C" in the sense of the present invention 10 The term "alkyl" comprises straight-chain or branched saturated hydrocarbon groups having 1 to 10 carbon atoms, including, in particular, methyl, ethyl, n-propyl, isopropyl, n-butyl, sec-butyl, isobutyl, tert-butyl, n-pentyl, isopentyl, 2,2-dimethylpropyl, n-hexyl, isohexyl, 2-ethylhexyl, n-heptyl, isoheptyl, n-octyl, isooctyl, n-nonyl, n-decyl, and the like.

[0053] "C2-C" in the sense of the present invention 10 The term "alkenyl" comprises unsaturated linear or branched hydrocarbon groups having 2 to 10 carbon atoms, said hydrocarbon group having at least one C-C double bond, including, 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.

[0054] "C2-C" in the sense of the present invention 10 The term "alkynyl" comprises unsaturated linear or branched hydrocarbon groups having 2 to 10 carbon atoms, said hydrocarbon group having at least one C-C triple bond, including, in particular, ethynyl, 1-propynyl, 2-propynyl, 1-n-butynyl, 2-n-butynyl, isobutynyl, 1-pentynyl, 1-hexynyl, 1-heptynyl, 1-octynyl, 1-nonynyl, 1-decynyl, and the like.

[0055] "C3-C" in the sense of the present invention 10 The term "cycloalkyl" comprises cyclic saturated hydrocarbon groups having 3 to 10 carbon atoms, including in particular cyclopropyl, cyclobutyl, cyclopentyl, cyclohexyl, cycloheptyl, cyclohexyl, cyclononyl and cyclodecanyl.

[0056] "C6-C" in the sense of the present invention 14 The term "aryl" comprises aromatic hydrocarbon groups having 6 to 14 ring carbon atoms. This includes, in particular, phenyl (C6H5 group), naphthyl (C 10 H7 group) and anthracyl (C 14 H9 group) is applicable.

[0057] "C5-C" in the sense of the present invention 14 The term "heteroaryl" comprises aromatic hydrocarbon groups having 5 to 14 cyclic hydrocarbon atoms, at least one of which is substituted or replaced by a nitrogen, oxygen or sulfur atom. This applies in particular to pyrrolyl, furanyl, thiophenyl, pyridinyl, pyranyl, thiopyranyl, etc. All of the aforementioned hydrocarbon groups are bonded to the central atom according to formula (I) via the respective oxygen atom.

[0058] The lithium tetrahaloaluminate may be lithium tetrachloroaluminate (LiAlCl4).

[0059] In another preferred embodiment of the rechargeable battery cell, the substituent R of the first conductive salt according to formula (I) 1 , R 2 , R 3 and R 4 are independently selected from the group formed by: - C1-C6 alkyl, preferably C2-C4 alkyl, particularly preferably 2-propyl, methyl and ethyl alkyl groups, - C2-C6 alkenyl, preferably C2-C4 alkenyl, particularly preferably ethenyl and propenyl alkenyl groups, - C2-C6 alkynyl, preferably C2-C4 alkynyl, - C3-C6 cycloalkyl, - phenyl, and - C5-C7 heteroaryl.

[0060] In this advantageous embodiment of the SO2-based electrolyte, the term "C1-C6 alkyl" comprises a linear or branched saturated hydrocarbon group having 1 to 6 hydrocarbon groups, in particular methyl, ethyl, n-propyl, isopropyl, n-butyl, sec-butyl, isobutyl, tert-butyl, n-pentyl, isopentyl, 2,2-dimethylpropyl, n-hexyl and isohexyl. Of these, C2-C4 alkyl is preferred. Particularly preferred are the C2-C4 alkyls 2-propyl, methyl and ethyl.

[0061] In this advantageous embodiment of the SO2-based electrolyte, the term "C2-C6 alkenyl" comprises an unsaturated linear or branched hydrocarbon group having 2 to 6 carbon atoms, said hydrocarbon group having at least one C-C double bond. This applies in particular to ethenyl, 1-propenyl, 2-propenyl, 1-n-butenyl, 2-n-butenyl, isobutenyl, 1-pentenyl, 1-hexenyl, with C2-C4 alkenyl being preferred. Particularly preferred are ethenyl and 1-propenyl.

[0062] In this advantageous embodiment of the SO2-based electrolyte, the term "C2-C6 alkynyl" comprises an unsaturated linear or branched hydrocarbon group having 2 to 6 carbon atoms, said hydrocarbon group having at least one C-C triple bond. This applies in particular to ethynyl, 1-propynyl, 2-propynyl, 1-n-butynyl, 2-n-butynyl, isobutynyl, 1-pentynyl, and 1-hexynyl. Of these, C2-C4 alkynyl is preferred.

[0063] In this advantageous embodiment of the SO2-based electrolyte, the term "C3-C6 cycloalkyl" comprises a cyclic saturated hydrocarbon group having 3 to 6 carbon atoms, including in particular cyclopropyl, cyclobutyl, cyclopentyl and cyclohexyl.

[0064] In this advantageous embodiment of the SO2-based electrolyte, the term "C5-C7 heteroaryl" comprises phenyl and naphthyl.

[0065] In another preferred embodiment of the rechargeable battery cell, the substituent R 1 , R 2 , R 3 and R 4 is substituted with at least one fluorine atom and / or at least one chemical group, said chemical group being selected from the group formed by C1-C4 alkyl, C2-C4 alkenyl, C2-C4 alkynyl, phenyl and benzyl. The chemical groups C1-C4 alkyl, C2-C4 alkenyl, C2-C4 alkynyl, phenyl and benzyl have similar properties or chemical structures as the aforementioned hydrocarbon groups. Substitution in this context means that the substituent R 1 , R 2 , R 3 and R 4 is substituted by said fluorine atom and / or said chemical group.

[0066] The substituent R1 , R 2 , R 3 and R 4 When at least one of the groups is a CF3 group or an OSO2CF3 group, it is possible to obtain extremely high solubility of the first conductive salt in the SO2-based electrolyte.

[0067] In another advantageous development of the rechargeable battery cell, the first conductive salt according to formula (I) is selected from the group formed by:

[0068] [ka]

[0069] In order to adapt the conductivity and / or other properties of the electrolyte to the desired values, in another advantageous embodiment of the rechargeable battery cell according to the invention, the electrolyte comprises at least one second conductive salt different from the first conductive salt, which means that in addition to the first conductive salt, the electrolyte may comprise one or more second conductive salts which differ from the first conductive salt not only in their chemical composition but also in their chemical structure.

[0070] In yet another preferred embodiment of the rechargeable battery cell according to the invention, the electrolyte comprises at least one additive 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 carbonate, sulfones, cyclic and acyclic sulfonates, acyclic sulfites, cyclic and acyclic sulfinic acid esters, organic esters of inorganic acids, acyclic and cyclic alkanes (including the acyclic and and cyclic alkanes having a boiling point of at least 36° C. at 1 bar), aromatic compounds, halogenated cyclic and acyclic sulfonylimides, halogenated cyclic and acyclic phosphate esters, halogenated cyclic and acyclic phosphines, halogenated cyclic and acyclic phosphites, halogenated cyclic and acyclic phosphazenes, halogenated cyclic and acyclic silylamines, halogenated cyclic and acyclic halogenated esters, halogenated cyclic and acyclic amides, halogenated cyclic and acyclic anhydrides and halogenated organic heterocycles.

[0071] In another preferred development of the rechargeable battery cell according to the invention, the electrolyte has the following composition, relative to the total weight of the electrolyte composition: (i) 5 to 99.4 wt. % sulfur dioxide; (i) 0.6 to 95 wt % of the first conductive salt; (iii) 0 to 25 wt % of said second conductive salt, and (iV) 0 to 10 wt % of said additive.

[0072] As described above, the electrolyte can contain not only one first conductive salt and one second conductive salt, but also multiple first conductive salts and multiple second conductive salts. In the latter case, the aforementioned ratio includes multiple first conductive salts and multiple second conductive salts. The concentration of the first conductive salt by mass of the total volume of the electrolyte 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 particularly preferably 0.2 mol / L to 3.5 mol / L.

[0073] In another preferred embodiment of the rechargeable battery cell according to the present invention, the electrolyte contains at least 0.1 mol SO per mol of conductive salt, preferably at least 1 mol SO, more preferably at least 5 mol SO, even more preferably at least 10 mol SO, and particularly preferably at least 20 mol SO. The electrolyte can also contain a very high molar ratio of SO, with a preferred upper limit of 2600 mol SO per mol of conductive salt, with upper limits of 1500, 1000, 500, and 100 mol SO per mol of conductive salt being preferred in that order. The term "per mol of conductive salt" refers to the total amount of conductive salt contained in the electrolyte. SO-based electrolytes with this concentration ratio between SO and the conductive salt have the advantage that they can dissolve a larger amount of conductive salt than electrolytes known in the prior art, for example, based on organic solvent mixtures. Within the scope of the present invention, it has been surprisingly found that electrolytes having a relatively low concentration of conductive salt are advantageous, despite the associated increase in vapor pressure, particularly with regard to their stability over multiple charge-discharge cycles of the rechargeable battery cell. The SO2 concentration in the electrolyte affects the electrolyte's conductivity. Therefore, by selecting the SO2 concentration, the electrolyte's conductivity can be adapted to the intended use of the rechargeable battery cell operated by the electrolyte. The total weight of SO2 and the first conductive salt can be greater than 50 weight percent (wt%) of the weight of the electrolyte, preferably greater than 60 wt%, more preferably greater than 70 wt%, more preferably greater than 80 wt%, more preferably greater than 85 wt%, more preferably greater than 90 wt%, more preferably greater than 95 wt%, or even more preferably greater than 99 wt%.

[0074] The electrolyte may contain at least 5 wt% SO2 with respect to the total amount of electrolyte contained in the rechargeable battery cell, with values ​​of 20 wt% SO2, 40 wt% SO2, and 60 wt% SO2 being more preferred. The electrolyte may contain up to 95 wt% SO2, with maximum values ​​of 80 wt% SO2 and 90 wt% SO2 being more preferred in that order.

[0075] It is within the scope of the present invention for the electrolyte to contain little or no organic solvent. For example, the proportion of organic solvent in the electrolyte, present in the form of a solvent or a mixture of organic solvents, can be at most 50 wt% of the electrolyte's weight. Particularly preferred are smaller proportions, such as at most 40 wt%, at most 30 wt%, at most 20 wt%, at most 15 wt%, at most 10 wt%, at most 5 wt%, or at most 1 wt% of the electrolyte's weight. It is even more preferred that the electrolyte contains no organic solvent. The low or complete absence of organic solvents results in the electrolyte having little or no flammability, which improves the operational safety of rechargeable battery cells operated with this type of SO2-based electrolyte. It is particularly preferred that the SO2-based electrolyte be substantially free of organic solvents.

[0076] In another advantageous development of the rechargeable battery cell, the electrolyte has the following composition, relative to the total weight of the electrolyte composition: (i) 5 to 99.4 wt. % sulfur dioxide; (ii) 0.6 to 95 wt % of the first conductive salt; (ii) 0 to 25 wt % of said second conductive salt; (iV) 0 to 10 wt % of said additive, and (V) 0 to 50 wt% organic solvent.

[0077] active metal Advantageous developments of the rechargeable battery cell according to the invention with respect to the active metal are described below:

[0078] In an advantageous development of the rechargeable battery cell, the active metal is: alkali metals, in particular lithium or sodium, - alkaline earth metals, especially calcium, - metals of group 12 of the periodic table, especially zinc, or - Aluminum.

[0079] negative electrode Advantageous developments of the rechargeable battery cell according to the invention with respect to the negative electrode are described below:

[0080] In another advantageous development of the rechargeable battery cell, the negative electrode is an insertion electrode. The insertion electrode contains an insertion material as an active material, and ions of the active metal are stored in the insertion material during charging of the rechargeable battery cell and released from the insertion material during discharging of the rechargeable battery cell. This means that electrode processes can be carried out not only on the surface of the negative electrode but also inside the negative electrode. For example, when using a lithium-based conductive salt, lithium ions can be stored in the insertion material during charging of the rechargeable battery cell and released from the insertion material during discharging of the rechargeable battery cell. The negative electrode preferably contains carbon, in particular modified graphite, as an active or insertion material. However, it is also within the scope of the present invention that the carbon be in the form of natural graphite (flaked promoter or round), synthetic graphite (mesophase graphite), graphitized mesocarbon microbeads (MCMB), carbon-coated graphite, or amorphous carbon.

[0081] In another advantageous development of the rechargeable battery cell according to the invention, the negative electrode is made of, for example, lithium titanate (e.g. Li4Ti5O 12 ) or the like.

[0082] In another advantageous development of the rechargeable battery cell according to the invention, the negative electrode comprises an active negative electrode material that forms an alloy with lithium, such as metals and metal alloys that store lithium (e.g., Si, Ge, Sn, SnCo). x C y , SnSi x etc.) and oxides of metals and metal alloys that store lithium (e.g., SnO x , SiO x or oxide glasses of Sn, Si, etc.

[0083] In another advantageous development of the rechargeable battery cell according to the invention, the negative electrode comprises a converted negative electrode active material, for example manganese oxide (MnO x ), iron oxide (FeO x ), cobalt oxide (CoO x ), nickel oxide (NiO x ), copper oxide (CuO x ), metal hydrides in the form of magnesium hydride (MgH2), titanium hydride (TiH2), aluminum hydride (AlH3), and ternary hydrides based on boron, aluminum, and magnesium. It is important that the binder of the negative electrode does not impair the good electrical connection of any one of the active materials to the planar conductor element, and the use of the first and second binders provides a good electrical connection of the active materials to the planar conductor element of the negative electrode, and the electrical connection is maintained during operation in the battery.

[0084] In another advantageous development of the rechargeable battery cell according to the invention, the negative electrode comprises a metal, in particular metallic lithium.

[0085] In another advantageous development of the rechargeable battery cell according to the invention, the negative electrode is porous, preferably with a porosity of at most 50%, more preferably at most 45%, even more preferably at most 40%, even more preferably at most 35%, even more preferably at most 30%, even more preferably at most 20%, and particularly preferably at most 10%. The porosity refers to the void volume relative to the total volume of the negative electrode, which is formed by so-called pores or voids. This porosity increases the internal surface of the negative electrode. Furthermore, this porosity reduces the density and thus the weight of the negative electrode. The individual pores of the negative electrode can preferably be completely filled with the electrolyte during operation.

[0086] In the battery cell according to the present invention, the negative electrode has a planar conductor element. This means that the negative electrode contains a planar conductor element in addition to the active material or the intercalation material. The planar conductor element is preferably a thin metal sheet or a thin metal foil. The thin metal foil preferably has a perforated or mesh structure. The planar conductor element can also consist of a metal-coated plastic foil. The metal coating has a thickness in the range of 0.1 μm to 20 μm. The active material of the negative electrode is preferably applied to the surface of the thin metal sheet, the thin metal foil, or the metal-coated plastic foil. The active material can be applied to the front and / or back of the planar conductor element. This type of planar conductor element has a thickness in the range of 5 μm to 50 μm. The thickness of the planar conductor element is preferably in the range of 10 μm to 30 μm. When planar conductor elements are used, the total thickness of the negative electrode can be at least 20 μm, preferably at least 40 μm, and particularly preferably at least 60 μm. The maximum thickness is at most 200 μm, preferably at most 150 μm and particularly preferably at most 100 μm. The area-specific capacitance of the coating on one surface of the negative electrode is preferably at least 0.5 mAh / cm when a planar conductor element is used. 2 and the following values ​​in this order are preferred: 1 mAh / cm 2 , 3mAh / cm 2 , 5mAh / cm 2 , 10mAh / cm 2 , 15mAh / cm 2 , 20mAh / cm 2 When the conductor element is formed in a planar form in the form of a thin metal sheet, a thin metal foil, or a metal-coated plastic foil, the amount of the active material of the negative electrode, i.e., the electrode loading in terms of surface coating, is at least 1 mg / cm 2 , preferably at least 3 mg / cm 2 , and more preferably at least 5 mg / cm 2 , and more preferably at least 8 mg / cm 2, and more preferably at least 10 mg / cm 2 and particularly preferably at least 20 mg / cm 2 The maximum loading of the electrode with respect to the coating on one side is preferably at most 150 mg / cm 2 , and more preferably at most 100 mg / cm 2 and particularly preferably at most 80 mg / cm 2 is.

[0087] In another advantageous development of the battery cell, the negative electrode comprises at least one further binder different from the first and second binders, which further binder is preferably one of the following: fluorinated binders, in particular polyvinylidene fluoride (abbreviated PVDF) and / or terpolymers formed by tetrafluoroethylene, hexafluoropropylene and vinylidene fluoride, or - Polymers consisting of monomeric structural units of conjugated carboxylic acids or alkali metal, alkaline earth metal or ammonium salts of said conjugated carboxylic acids, or combinations thereof.

[0088] The other binder in the form of a polymer may be lithium polyacrylate (LiPAA). The negative electrode may also have two other binders different from the first and second binders. In this case, the negative electrode preferably comprises a third binder in the form of a fluorinated binder, in particular polyvinylidene fluoride (abbreviated as PVDF) and / or a terpolymer formed by tetrafluoroethylene, hexafluoropropylene and vinylidene fluoride, and a fourth binder in the form of a polymer consisting of monomer structural units of conjugated carboxylic acids or alkali metal salts, alkaline earth metal salts or ammonium salts of the conjugated carboxylic acids, or a combination thereof.

[0089] The use of fluorinated binders presents a problem: they are often soluble only in organic solvents, which are highly flammable and harmful to the environment. Manufacturing anodes using fluorinated binders requires the use of complex equipment designed to accommodate the use of such solvents. This poses particular challenges for explosion prevention, environmental protection, and protection of staff from radiation exposure. This issue was a consideration for the Applicant when developing advantageous developments of the battery cell of the present invention. During the development of the rechargeable battery cell of this patent application, the Applicant discovered that it was difficult to determine the optimal binder concentration relative to the total weight of the anode: if the concentration in the anode is too low, the resulting anode becomes difficult to handle. For example, an electrode without a binder lacks adhesion to the conductor element, which can lead to particle release of the active material, rendering the resulting rechargeable battery cell unusable. Excessive binder concentration also adversely affects the energy density of rechargeable battery cells, since the weight of the binder reduces the energy density. Furthermore, a high binder concentration impairs the wettability of the anode with an SO2-based electrolyte. Therefore, the concentration of all binders in the negative electrode is preferably at most 20 wt%, more preferably at most 15 wt%, even more preferably at most 10 wt%, even more preferably at most 7 wt%, even more preferably at most 5 wt%, even more preferably at most 2 wt%, even more preferably at most 1 wt%, and particularly preferably at most 0.5 wt%, based on the total weight of the negative electrode. The concentration of all binders in the negative electrode is preferably in the range of 0.05 wt% to 20 wt%, more preferably in the range of 0.5 wt% to 10 wt%, and particularly preferably in the range of 0.5 wt% to 5 wt%. These concentrations enable good wetting of the negative electrode with SO2-based electrolytes, good handling of the negative electrode, and good energy density of rechargeable battery cells using such negative electrodes. In another advantageous development of the battery cell according to the invention, the negative electrode comprises at least one conductive additive. The conductive additive preferably has low weight, high chemical resistance, and a high specific surface area.Examples of said conductive additives are particulate carbon (carbon black, Super P, acetylene black), fibrous carbon (carbon nanotubes CNT, carbon (nano)fibers), finely divided graphite and graphene (nanosheets).

[0090] Rechargeable battery cell structure Advantageous developments of the rechargeable battery cell according to the invention with respect to its structure are explained below:

[0091] In order to further improve the functionality of the rechargeable battery cell, in another advantageous development of the rechargeable battery cell according to the invention, the rechargeable battery cell has a plurality of negative electrodes and a plurality of positive electrodes arranged in an alternating stack in a housing, the positive electrodes and the negative electrodes being preferably electrically separated from each other by separators.

[0092] However, the rechargeable battery cell may also be configured as a coil cell, in which the electrodes are formed as thin layers wound with a separator material. The separator spatially and electrically separates the positive and negative electrodes, and is permeable, particularly to ions of the active metal. This creates a large electrochemically effective surface, which allows for a correspondingly high current yield. The separator can be made of nonwoven fabrics, membranes, woven fabrics, knitted fabrics, organic materials, inorganic materials, or a combination thereof. Organic separators can be made of, for example, unsubstituted polyolefins (e.g., polypropylene or polyethylene), partially to fully halogen-substituted polyolefins (e.g., partially to fully fluorinated ones, especially PVDF, ETFE, PTFE), polyesters, polyamides, or polysulfones. Separators comprising a combination of organic and inorganic materials are, for example, woven glass fiber materials in which glass fibers are provided with an appropriate polymer coating. The coating is a fluorine-containing polymer such as polytetrafluoroethylene (PTFE), ethylene tetrafluoroethylene (ETFE), perfluoroethylene propylene (FEP), THV (a terpolymer of tetrafluoroethylene, hexafluoroethylene, and vinylidene fluoride), perfluoroalkoxy polymer (PFA), aminosilane, polypropylene, or polyethylene (PE). The separator can be folded, for example, in a so-called "Z-fold" shape within the housing of the rechargeable battery cell. In the Z-folding configuration, the strip-shaped separator is folded in a Z shape so as to pass through the electrodes or around the electrodes. The separator can also be formed as separator paper.

[0093] It is also within the scope of the present invention that the separator may be formed as a coating, and each high-voltage positive electrode or each high-voltage negative electrode may be covered with the coating, which may be formed using a nonwoven fabric, a membrane, a woven fabric, a knitted fabric, an organic material, an inorganic material, or a combination thereof.

[0094] The coating of the positive electrode allows for uniform ion migration and distribution in the rechargeable battery cell. A more uniform ion distribution, especially in the negative electrode, allows for a greater possible loading of active material into the negative electrode, thereby increasing the usable capacity of the rechargeable battery cell. At the same time, the risk of uneven loading and the resulting precipitation of the active metal is avoided. This advantage is particularly pronounced when the positive electrode of the rechargeable battery cell is covered with the coating.

[0095] The surface dimensions of the electrode and the coating are preferably adjusted to one another so that the outer dimensions of the coating on the electrode and the outer dimensions of the uncoated electrode match in at least one dimension.

[0096] Preferably, the surface area of ​​the coating may be larger than the surface area of ​​the electrode, in which case the coating extends beyond the boundaries of the electrode, so that two layers of the coating covering both sides of the electrode may be connected to each other at the edge of the positive electrode by an edge connection.

[0097] In another advantageous embodiment of the rechargeable battery cell according to the invention, the negative electrode has a coating whereas the positive electrode does not have a coating.

[0098] Further advantageous properties of the present invention are described and explained in detail below with the aid of figures, examples and experiments. [Brief explanation of the drawings]

[0099] [Figure 1] 1 is a cross-sectional view of a first example embodiment of a rechargeable battery cell according to the present invention; [Figure 2] FIG. 2 is a detailed view of the first embodiment example according to FIG. 1; [Figure 3] FIG. 2 is an exploded view of a second example embodiment of a rechargeable battery cell according to the present invention. [Figure 4] FIG. 10 is an exploded view of a third example embodiment of a rechargeable battery cell according to the present invention. [Figure 5] FIG. 1 shows the potential (in [V]) as a function of capacity relative to the theoretical capacity of the negative electrode for three experimental complete cells having electrodes with various binder combinations and three-dimensional conductor elements at the time of surface layer formation and filled with the lithium tetrachloroaluminate electrolyte of Example 1. [Figure 6] FIG. 1 shows the discharge capacity as a function of cycle number for three experimental complete cells having electrodes with various binder combinations and three-dimensional conductor elements, and filled with the lithium tetrachloroaluminate electrolyte of Example 1. [Figure 7] FIG. 1 shows the potential (in [V]) as a function of capacity for three half-cells with various binder combinations and planar conductor elements, and with electrodes filled with Electrolyte 1 from Example 1. [Figure 8] FIG. 1 shows the discharge capacity as a function of cycle number for two half-cells having electrodes filled with Electrolyte 1 of Example 1, with various binder combinations and planar conductor elements. [Figure 9] FIG. 1 shows the potential (units [V]) of three coil cells having electrodes filled with Electrolyte 1 of Example 1, with various binder combinations and planar conductor elements, during charging during the formation of a surface layer on the negative electrode, as a function of capacity relative to the theoretical capacity of the negative electrode. [Figure 10] FIG. 1 shows the discharge capacity as a function of cycle number for two coil cells having electrodes filled with Electrolyte 1 of Example 1, with various binder combinations and planar conductor elements. [Figure 11] FIG. 1 shows the potential (in [V]) of three experimental complete cells filled with electrolytes 1 and 3 according to Example 1 and a lithium tetrachloroaluminate electrolyte during charging during the formation of a surface layer on the negative electrode as a function of capacity relative to the theoretical capacity of the negative electrode. [Figure 12] FIG. 1 shows the potential course (in [V]) as a function of the charge rate during discharge of three experimental complete cells filled with electrolytes 1, 3, 4 and 5 according to Example 1 and containing lithium nickel manganese cobalt oxide (NMC) as the electrode active material. [Figure 13] FIG. 2 shows the conductivity (units [mS / cm]) of electrolytes 1 and 4 according to Example 1 depending on the concentration of compounds 1 and 4. [Figure 14] FIG. 1 shows the conductivity (units [mS / cm]) of electrolytes 3 and 5 according to Example 1 depending on the concentration of compounds 3 and 5. DETAILED DESCRIPTION OF THE INVENTION

[0100] FIG. 1 illustrates a cross-sectional view of a first embodiment of a rechargeable battery cell 20 according to the present invention. This first embodiment shows an electrode unit having one positive electrode 23 and two negative electrodes 22. The electrodes 22, 23 are separated from each other by a separator 21 and surrounded by a housing 28. The positive electrode 23 has a conductor element 26 in the form of a planar metal foil, coated on both sides with a homogeneous mixture of the active material 24 of the positive electrode 23, a first binder SBR, and a second binder CMC. The negative electrode 22 also has a conductor element 27 in the form of a planar metal foil, coated on both sides with a homogeneous mixture of the active material 25 of the negative electrode 22, a first binder SBR, and a second binder CMC. Alternatively, the planar conductor element of the edge electrode, i.e., the electrode that closes the electrode stack, can be coated with active material on only one side. The uncoated side faces the wall of the housing 28. The electrodes 22, 23 are connected via electrode connections 29, 30 to corresponding connection contacts 31, 32 of the rechargeable battery cell 20.

[0101] Figure 2 illustrates the planar metal foil used as the conductor elements 26, 27 of the positive electrode 23 and the negative electrode 22, respectively, in the second example embodiment of Figure 1. The metal foil has a perforated or mesh structure with a thickness of 20 μm.

[0102] FIG. 3 shows an exploded view of a second embodiment of a rechargeable battery cell 40 according to the present invention. This second embodiment differs from the first embodiment in that the positive electrode 44 is covered with a coating 13 that functions as a separator. The surface area of ​​the coating 13 is larger than that of the positive electrode 44, and the boundary 14 of the positive electrode is indicated by a dashed line in FIG. 5. The two layers 15, 16 of the coating 13 that cover both sides of the positive electrode 44 are connected to each other by an edge connection 17 at the periphery of the positive electrode 44. The negative electrodes 45 are uncoated. The electrodes 44 and 45 can be contacted via electrode connections 46 and 47.

[0103] FIG. 4 shows an exploded view of a third embodiment of a rechargeable battery cell 101 according to the present invention. The essential structural elements of the battery cell 101 are shown, including a wound electrode unit. The electrode unit 105 is formed by rolling a sheet of starting material into a cylindrical housing 102 with a cover 103. The sheet is composed of multiple layers, including one positive electrode, one negative electrode, and a separator extending between the electrodes. The separator electrically and mechanically isolates the electrodes from each other while being sufficiently porous or ionically conductive to allow the necessary ion exchange. The positive electrode comprises a conductor element in the form of a planar metal foil, coated on both sides with a homogeneous mixture of the active material 24 of the positive electrode 23, a first binder SBR, and a second binder CMC. The negative electrode also has a conductor element in the form of a planar metal foil on both sides of which is coated a homogeneous mixture of the active material 25 of the negative electrode 22, the first binder SBR and the second binder CMC.

[0104] The cavity of the housing 102 is filled with an electrolyte, not shown, unless it is occupied by the electrode unit 105. The positive and negative poles of the electrode unit 105 are connected to a terminal connection 108 for the positive pole and a terminal connection 109 for the negative pole via a corresponding terminal lug 106 for the positive pole and a corresponding terminal lug 107 for the negative pole, thereby enabling electrical connection of the rechargeable battery cell 101. As an alternative to the electrical connection of the negative pole via the terminal lug 107 and the terminal connection 109, as shown in Figure 4, the electrical connection of the negative pole can also be made through the housing 102.

[0105] Example 1: Fabrication of an Example Embodiment of an SO2-Based Electrolyte for a Battery Cell The electrolyte LiAlCl4*xSO2 used in the experiments described below was prepared according to the method described in EP 2954588 (hereinafter referred to as [V6]). First, lithium chloride (LiCl) was dried under vacuum at 120°C for three days. Aluminum particles (Al) were dried under vacuum at 450°C for two days. LiCl, aluminum chloride (AlCl3), and Al were mixed together in a glass bottle with an opening for gas release to obtain a molar ratio of AlCl3:LiCl:Al of 1:1.06:0.35. The mixture was then heated in stages to produce a molten salt. After cooling, the formed molten salt was filtered and cooled to room temperature. Finally, SO2 was added until the desired molar ratio of LiAlCl4 to SO2 was obtained. The electrolyte thus formed had the composition LiAlCl4*xSO2, where x depends on the amount of SO2 added. In the experiments, this electrolyte is referred to as lithium tetrachloroaluminate electrolyte.

[0106] For the experiments described below, five examples 1, 2, 3, 4 and 5 of SO2-based electrolytes having one conductive salt according to formula (I) were prepared (hereinafter referred to as electrolytes 1, 2, 3, 4 and 5). For this purpose, five different first conductive salts according to formula (I) were first prepared according to the preparation methods described in the following documents [V7], [V8] and [V9]: [V7]I. Krossing, Chem. Eur. J. 2001, 7, 490 [V8]SM Ivanova et al., Chem. Eur. J. 2001, 7, 503 [V9]Tsujioka et al., J. Electrochem. Soc., 2004, 151, A1418

[0107] The five different first conductive salts according to formula (I) are hereinafter referred to as compounds 1, 2, 3, 4, and 5. The compounds are a family of polyfluoroalkoxyaluminates, which can be prepared by the reaction of LiAlH4 with the corresponding alcohol R-OH(R 1 =R 2 =R 3 =R 4 ) and prepared according to the following reaction scheme:

[0108] [ka]

[0109] This formed compounds 1, 2, 3, 4 and 5, which have the molecular or structural formulae shown below:

[0110] [ka]

[0111] For purification, compounds 1, 2, 3, 4, and 5 were first recrystallized to remove any residual educt LiAlH4 from the first conductive salt, which could spark with traces of water that may be present in SO2.

[0112] Then, the compounds 1, 2, 3, 4 and 5 were dissolved in SO2. Compounds 1, 2, 3, 4 and 5 were found to be highly soluble in SO2.

[0113] The electrolytes 1, 2, 3, 4 and 5 were prepared by the following methods: Steps 1 to 4 were performed at low temperature or under pressure: 1) Each of compounds 1, 2, 3, 4 and 5 is placed in a pressure flask equipped with a riser pipe. 2) Emptying the pressure flask; 3) Injecting liquid SO2, and 4) Repeat steps 2 and 3 until the target amount of SO2 has been added.

[0114] The concentrations of the compounds 1, 2, 3, 4 and 5 in the electrolytes 1, 2, 3, 4 and 5 were each 0.6 mol / l (substance concentration per liter of electrolyte) unless otherwise specified in the following experimental description.

[0115] The lithium tetrachloroaluminate electrolyte and electrolytes 1, 2, 3, 4 and 5 were used to carry out the experiments described below.

[0116] Example 2: Preparation of a complete experimental cell The experimental complete cells used in the experiments described below were rechargeable battery cells containing two negative electrodes and one positive electrode, each separated by a separator. The positive electrode contained an active material, a conductive additive, and two binders. The negative electrode contained graphite as the active material and two binders. As noted in the experiments, the negative electrode may also contain a conductive additive. The active material of the positive electrode is noted in each experiment. Among other things, the purpose of the experiments was to demonstrate the use of various binders or binder combinations in electrodes with planar conductor elements in battery cells with SO2-based electrolytes according to the present invention. Table 2a lists the binders investigated. Table 2b lists the binder combinations used in the experiments.

[0117] The experimental complete cells were filled with the electrolyte required for each experiment, i.e., the lithium tetrachloroaluminate electrolyte or Electrolytes 1, 2, 3, 4, or 5. Typically, multiple identical experimental complete cells, i.e., two to four, were prepared for each experiment, and the results shown for each experiment are the average of the measurements obtained for each identical experimental complete cell.

[0118] [Table 2a]

[0119] [Table 2b]

[0120] Example 3 Measurements in a complete experimental cell Surface capacity: The capacity consumed in the first cycle to form a surface layer on the negative electrode is an important criterion for the quality of the battery cell. This surface layer is formed on the negative electrode during the first charge of the experimental full cell. Because lithium ions are irreversibly consumed to form this surface layer (surface capacity), the cyclable capacity available for the experimental full cell in subsequent cycles is reduced. The surface capacity (unit [%]) relative to the theoretical value used to form the surface layer on the negative electrode is calculated using the following formula:

[0121] Surface capacitance [% of theoretical value] = (Q lad (xmAh)-Q ent (ymAh)) / Q NEL

[0122] Q lad is the charge amount (unit: mAh) specified in each experiment, and Q ent Q is the charge (unit: mAh) obtained when the experimental complete cell is subsequently discharged. NEL is the theoretical capacity of the negative electrode used. In the case of graphite, for example, the theoretical capacity is calculated based on a value of 372 mAh / g.

[0123] Discharge capacity: For example, in measurements of experimental complete cells, the discharge capacity is determined by the number of cycles. To this end, the experimental complete cell is charged to a predetermined upper potential limit at a predetermined charging current. The corresponding upper potential limit is maintained until the charging current drops to a certain value. Then, the cell is discharged at a predetermined discharge current until the predetermined discharge potential is reached. This charging method is called I / U charging. This process is repeated for the desired number of cycles.

[0124] The upper limit potential or the discharge capacity and the respective charge and discharge current are described in the experiments, as well as the value to which the charge current should be reduced.

[0125] The term "upper potential limit" is used synonymously with the terms "charging potential," "charging voltage," "end-of-charge voltage," and "upper potential limit," which refer to the voltage / potential that a cell or battery must reach when being charged by a battery charging device.

[0126] The battery is preferably charged at a current rate of C / 2 and a temperature of 22°C. By definition, a 1C charge / discharge rate will charge / discharge the nominal capacity of the cell in one hour. Therefore, a C / 2 current rate means a two-hour charge time.

[0127] The term "discharge potential" is used interchangeably with the term "bottom cell voltage," which refers to the voltage / potential that a cell or battery must reach when it is discharged by a battery charger.

[0128] Discharging of the battery is preferably carried out at a current rate of C / 2 and at a temperature of 22°C.

[0129] The discharge capacity is determined by the discharge current and the time until the criteria for terminating discharge are met. The associated figures show the average discharge capacity as a function of the cycle number. The average discharge capacity is often normalized to the maximum capacity obtained in an experiment and expressed as a percentage of the nominal capacity.

[0130] [Experiment 1] Investigation of various binder combinations in an experimental complete cell with three-dimensional conductive elements Prior art rechargeable battery cells with SO2-based electrolytes use electrodes with three-dimensional conductor elements, mainly consisting of, for example, nickel foam (see [V5]). The preferred binder for the negative electrode is lithium polyacrylate (LiPAA) (see [V4]). Negative electrodes (NEL) were produced with graphite as active material and various binder combinations. All electrodes comprised three-dimensional conductor elements in the form of nickel foam, as known from the prior art. The binder combinations were: 2wt% LiPAA / 2wt% CMC, 2 wt% LiPAA / 2 wt% SBR, and 2wt%SBR / 2wt%CMC.

[0131] Two identical negative electrodes and one positive electrode containing lithium iron phosphate (LEP) as the electrode active material were assembled according to Example 2 to form Experimental Complete Cell 1. Three experimental complete cells were obtained, each with a different binder combination in the negative electrode. All three experimental complete cells were filled with lithium tetrachloroaluminate electrolyte having a composition of LiAlCl4*6SO2 according to Example 1.

[0132] First, the surface capacitance was determined according to Example 3 in the first cycle.

[0133] For this purpose, the experimental complete cell was charged with 125mAh (Q ladThe experimental complete cell was then discharged at 15 mA until a potential of 2.5 volts was reached. ent ) was sought.

[0134] FIG. 5 shows the potential (unit: [V]) of various experimental complete cells during charging of the negative electrode as a function of the capacity (unit: [%]) relative to the theoretical capacity of the negative electrode.

[0135] The measured surface capacities (units [% of theoretical capacity of negative electrode]) of the various negative electrodes were as follows: NEL 2% SBR / 2% CMC: 7.48% of the theoretical value of the negative electrode NEL 2% LiPAA / 2% CMC: 7.15% of the theoretical value of the negative electrode NEL 2% LiPAA / 2% SBR: 9.34% of the theoretical value of the negative electrode

[0136] The surface capacitance is lowest for the binder combination of 2% LiPAA / 2% CMC.

[0137] To determine the discharge capacity (see Example 3), the experimental complete cell was charged to a maximum potential of 3.6 volts at a current of 100 mA. The 3.6 volt potential was held until the current dropped to 40 mA. It was then discharged to a discharge potential of 2.5 volts at a discharge current of 100 mA.

[0138] Figure 6 shows the average discharge capacity of the experimental full cells as a function of cycle number. 500 cycles were performed. The average discharge capacity is expressed as a percentage of nominal capacity [% of nominal capacity].

[0139] The discharge capacity profiles of the experimental full cells show a uniformly small decreasing profile, however the capacity loss is least in the experimental full cells containing graphite electrodes with a binder combination of 2% LiPAA / 2% CMC.

[0140] When using three-dimensional conductive elements in the form of nickel foam conductive elements, negative electrodes containing a binder combination of 2% LiPAA / 2% CMC exhibit lower surface capacity and better cycling behavior than negative electrodes with binder combinations of 2% LiPAA / 2% SBR or 2% SBR / 2% CMC, substantiating the statement in [V4] that a binder containing LiPAA has a positive effect when using three-dimensional conductive elements in the form of nickel foam conductive elements.

[0141] Experiment 2: Mechanical investigation of graphite with various binders on planar conductive elements. Mechanical investigations were first carried out to investigate the properties of graphite with different binders on planar conductor elements. On the one hand, the adhesion strength of the electrode material to the planar conductor element was determined, and on the other hand, the loading, i.e., 1 cm 2 An investigation was conducted on the amount of active material per electrode surface.

[0142] The adhesion of graphite with two different binder combinations on planar conductor elements was investigated using an MFC Sensor Technik Model T1000 tensile / compression tester. The test was a 90° peel test. Peel tests are used to confirm the properties of foils bonded to substrates in tensile tests. The coated foil under investigation was fixed on a carrier plate, and the free end was fixed in the tensile tester and pulled upward at a constant speed of 100 mm / min. During this process, the planar conductor element in the form of a foil peeled off from the electrode layer, and the adhesion force along the electrode foil was recorded. Tests were performed on two graphite electrodes with binders CMC-LiPAA-SBR (1%, 2%, and 1%) on metal foil as the planar conductor element (Electrode 1) and CMC-SBR (2%, and 1%) (Electrode 2). Table 3 shows the adhesion measurement results.

[0143] [Table 3]

[0144] Graphite with binder combinations containing a proportion of LiPAA exhibits significantly lower adhesion values ​​than graphite with binder combinations not containing a proportion of LiPAA. This means that in electrode 1, the graphite adheres poorly to the conductor element, potentially causing chipping of the electrode material due to mechanical loads during battery cell operation. In contrast, electrodes with CMC / SBR binder combinations exhibit good adhesion to planar conductor elements.

[0145] Possible filling volume in a planar conductor element, i.e. 1 cm 2 The amount of active material per electrode surface was investigated. To fabricate a planar electrode, a mixture of graphite and binder was prepared and processed with a solvent to obtain a homogeneous paste. The finished paste was spread homogeneously on a metal foil and dried in air or in an oven at low temperature. This step was necessary to remove the solvent from the electrode. After cooling, the electrode was compressed using a calender.

[0146] On the one hand, a binder mixture consisting of LiPAA (2 wt%) and CMC (2 wt%) was prepared, and on the other hand, a binder mixture consisting of SBR (2 wt%) and CMC (2 wt%) was prepared. Due to the poor mechanical properties of LiPAA on planar electrodes, approximately 5 mg / cm was applied to the metal foil. 2 Only 14 mg / cm of graphite / binder could be applied. When an SBR / CMC binder mixture was used, 14 mg / cm 2 It was possible to apply a desired amount of SBR / CMC binder combination to produce electrodes with high loadings and therefore high capacities.

[0147] [Experiment 3] Investigation of various binder combinations in half-cells with planar conductor elements and filled with electrolyte 1 First, graphite electrodes with various binder combinations were investigated in half-cells with three-electrode units, where the return and reference electrodes were each made of metallic lithium. The electrolyte used in the half-cells was electrolyte 1 from Example 1. The following binder combinations on the planar conductor elements were used: - Graphite electrode containing 3.0 wt% SBR and 1.0 wt% CMC - Graphite electrode containing 2.0 wt% SBR and 2.0 wt% CMC - Graphite electrodes containing approximately 2.0 to 4.0 wt% PVDF

[0148] PVDF has also been suggested as a suitable binder in the prior art (see [V3] and [V5]), so graphite electrodes containing this binder were also investigated. The surface capacity was first measured by charging half-cells at a rate of 0.1 C to a potential of 0.03 V and discharging them at the same rate to a potential of 0.5 V. The capacity loss from the first cycle was used to calculate the surface capacity. Figure 7 shows the potential (in volts) of various experimental complete cells during charging of the negative electrode as a function of the capacity (in % of the theoretical capacity of the negative electrode).

[0149] The surface capacitances (units [% of theoretical capacity of negative electrode]) determined for the various electrodes are as follows: NEL 3%SBR / 1%CMC: 14.0% of the theoretical value of the negative electrode NEL 2%SBR / 2%CMC: 14.0% of the theoretical value of the negative electrode NEL 2.0 to 4.0 wt% PVDF: 21.5% of the theoretical value of the negative electrode

[0150] The surface capacity of negative electrodes with PVDF binder is extremely high at 21.5%. This means that almost a quarter of the battery capacity is already used for surface layer formation. The use of PVDF binder alone in electrodes with planar conductor elements is not suitable for rechargeable battery cells with SO2-based electrolytes. However, it is possible to use the PVDF binder as an additional third binder in addition to the SBR / CMC binder combination.

[0151] In contrast, electrodes with SBR / CMC binder have a lower surface capacitance.

[0152] To determine the discharge capacity (see Example 3), half-cells with SBR / CMC binders were charged to a potential of 0.03 volts at a charge rate of 0.1 C and discharged to a potential of 0.5 V for cycles 1 through 5. From cycle 6 onward, the charge / discharge rate was increased to 1 C. Further charging maintained the potential of 0.03 V until the charge rate was reduced to 0.01 C. Figure 8 shows the average discharge capacity of both half-cells as a function of cycle number. 25 (2% SBR / 2% CMC) or 50 (3% SBR / 1% CMC) cycles were performed. The average discharge capacity was expressed as a percentage of the nominal capacity (unit: % of nominal capacity). Both half-cells exhibited a stable discharge capacity profile. The SBR and CMC binder combination in an SO2-based electrolyte is extremely well suited for electrodes with planar conductive elements.

[0153] [Experiment 4] Investigation of various binder combinations in a coil cell with planar conductive elements and filled with electrolyte 1 In addition to the half-cell experiments, coil cells were investigated with a positive electrode containing nickel manganese cobalt oxide (NMC811) as the active material and a negative graphite electrode with the following binder combinations: - 2.5wt%SBR / 1.5wt%CMC - 2.0wt%SBR / 2.0wt%CMC - 1.0wt%SBR / 2.0wt%CMC.

[0154] First, in the first cycle, the surface capacity was determined according to Example 3. For this purpose, the coil cell was charged with 0.9 Ah (Q lad The coil cell was charged at a current of 0.1 A until the potential reached 2.5 volts. The discharge capacity (Q ent ) was sought.

[0155] Figure 9 shows the potential (V) of various coil cells during charging of the negative electrode as a function of the capacity (% of the theoretical capacity) of the negative electrode. The surface capacity (% of the theoretical capacity of the negative electrode) was found to be approximately 11% or less of the theoretical value of the negative electrode for the three investigated coil cells, which is therefore a good value.

[0156] To determine the discharge capacity (see Example 3), coil cells with binder combinations of 2.5% SBR / 1.5% CMC and 2.0% SBR / 2.0% CMC were charged to an upper potential of 4.2 volts at a voltage of 0.2 A. They were then discharged to a potential of 2.8 volts at a discharge current of 0.2 A. The charge voltage was increased to 4.4 volts and then 4.6 volts and maintained for all subsequent cycles.

[0157] Figure 10 shows the average discharge capacity of the coil cells as a function of cycle number. 15 (2.5% SBR / 1.5% CMC) or 60 (2.0% SBR / 2.0% CMC) cycles were performed. The average discharge capacity was expressed as a percentage of the nominal capacity (unit: % of nominal capacity).

[0158] Both coil cells have a uniform, slightly decreasing profile. The SBR and CMC binder combination is also well suited for coil cells with SO2-based electrolytes and electrodes with planar conductor elements.

[0159] [Experiment 5] Investigation of Electrolytes 1, 3, 4, and 5 Various experiments were carried out to investigate electrolytes 1, 3, 4 and 5. On the one hand, the surface capacities of electrolytes 1 and 3 and lithium tetrachloroaluminate electrolyte were determined, and on the other hand, the discharge capacities of electrolytes 1, 3, 4 and 5 were measured.

[0160] To determine the surface capacity, three experimental complete cells were filled with electrolytes 1 and 3 described in Example 1 and a lithium tetrachloroaluminate electrolyte. The three experimental complete cells contained lithium iron phosphate as the positive electrode active material.

[0161] FIG. 11 shows the potential (in volts) of the experimental complete cell during charging as a function of capacity relative to the theoretical capacity of the negative electrode. The two curves shown represent the average results of multiple experiments performed using the experimental complete cell. First, a 125 mAh (Q lad The full cell was then discharged at 15 mA until it reached a potential of 2.5 volts. ent ) was sought.

[0162] The absolute capacity loss is 7.58% or 11.51% for the electrolytes 1 and 3, respectively, and 6.85% for the lithium tetrachloroaluminate electrolyte. The capacity due to surface layer formation is low for all electrolytes.

[0163] For discharge experiments, three experimental complete cells according to Example 2 were filled with electrolytes 1, 3, 4, and 5 described in Example 1. The experimental complete cells contained lithium nickel manganese cobalt oxide (NMC) as the positive electrode active material. To determine the discharge capacity (see Example 3), the experimental complete cells were charged to a capacity of 125 mAh using a current of 15 mA. They were then discharged to a discharge potential of 2.5 volts using a current of 15 mA.

[0164] Figure 12 shows the potential evolution during discharge as a percentage of the discharged charge (unit: [% of maximum charge (discharge)]). All experimental full cells show flat discharge curves, which is necessary for good battery cell operation.

[0165] [Experiment 6] Measurement of the conductivity of electrolytes 1, 3, 4, and 5 Electrolytes 1, 3, 4, and 5 were prepared with various concentrations of compounds 1, 3, 4, and 5 for conductivity measurements. The conductivity of the electrolytes was measured for each of the various compound concentrations using a conductance measurement method. After tempering, a four-electrode sensor was held in contact with the solution and measured over a measurement range of 0.02 to 500 mS / cm.

[0166] Figure 13 illustrates the conductivity of electrolytes 1 and 4 depending on the concentration of compound 1 or 4. A maximum conductivity of approximately 37.9 mS / cm is observed in electrolyte 1 when the concentration of compound 1 is between 0.6 mol / L and 0.7 mol / L. In comparison, organic electrolytes known from the prior art, such as LP30 (1 M LiPF / EC-DMC (1:1 by weight)), only have a conductivity of approximately 10 mS / cm. For electrolyte 4, a maximum of 18 mS / cm is obtained at a conductive salt concentration of 1 mol / L.

[0167] FIG. 14 illustrates the conductivity of electrolytes 3 and 5 depending on the concentration of compound 3 or 5.

[0168] For electrolyte 5, a maximum of 1.3 mS / cm is obtained when the conductive salt concentration is 0.8 mol / L. Electrolyte 3 exhibits a maximum conductivity of 0.5 mS / cm when the conductive salt concentration is 0.6 mol / L. Although the conductivities of electrolytes 3 and 5 were low, they were sufficient to allow charging or discharging of, for example, the experimental half-cell described in Experiment 3 or the experimental full cell described in Experiment 8.

[0169] [Experiment 7] Low-temperature behavior To compare the low-temperature behavior of Electrolyte 1 with that of the lithium tetrachloroaluminate electrolyte, two experimental complete cells were prepared according to Example 2. One experimental complete cell was filled with a lithium tetrachloroaluminate electrolyte having a composition of LiAlCl4*6SO2, and the other experimental complete cell was filled with Electrolyte 1. The experimental complete cell containing the lithium tetrachloroaluminate electrolyte contained lithium iron phosphate (LEP) as the positive electrode active material, while the experimental cell containing Electrolyte 1 contained lithium nickel manganese cobalt oxide (NMC) as the positive electrode active material. The experimental complete cells were charged to 3.6 V (LEP) or 4.4 V (NMC) at 20°C and then discharged again to 2.5 V at each investigated temperature. The discharge capacity achieved at 20°C was evaluated as 100%. The discharge temperature was decreased in 10°K temperature steps. The resulting discharge capacities were expressed as a percentage of the discharge capacity at 20°C. Since the low-temperature discharge is largely independent of the positive and negative electrode active materials used, the results are applicable to all active material combinations. Table 5 shows the results.

[0170] [Table 5]

[0171] The experimental complete cell with electrolyte 1 exhibits very good low-temperature behavior. At 20°C, it still reaches 82% of its capacity, and at -30°C, it still reaches 73%. Even at a temperature of -40°C, it is still possible to discharge 61% of its capacity. In contrast, the experimental complete cell with lithium tetrachloroaluminate electrolyte can only discharge down to -10°C, where it reaches 21% of its capacity. At lower temperatures, it is no longer possible to discharge the cell with lithium tetrachloroaluminate electrolyte.

Claims

1. SO 400 includes an active metal, at least one positive electrode (23, 44) having a planar conductor element (26), at least one negative electrode (22, 45) having a planar conductor element (27), a housing (28), and a conductive salt. ２ A rechargeable battery cell (20, 40, 101) comprising a system electrolyte, the positive electrode (23, 44) and / or the negative electrode (22, 45) comprises at least one first binder consisting of a polymer based on monomeric styrene and butadiene structural units and at least one second binder consisting of a carboxymethylcellulose group; The conductive salt is of the following formula (I): 【Chemistry 1】 It consists of M is a metal selected from the group formed by 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, - Substituent R １ , R ２ , R ３ and R ４ are independently 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 - The central atom Z is aluminum or boron A rechargeable battery cell (20, 40, 101).

2. 2. The rechargeable battery cell (20, 40, 101) of claim 1, wherein the positive electrode (23, 44) and / or the negative electrode (22, 45) has at least one other binder different from the first and second binders.

3. 3. The rechargeable battery cell (20, 40, 101) according to claim 1 or 2, characterized in that the concentration of all binders in the positive electrode (23, 44) or the negative electrode (22, 45) is at most 20 wt % with respect to the total weight of the positive electrode (23, 44) or the negative electrode (22, 45).

4. The substituent R of the conductive salt １ , R ２ , R ３ and R ４ are selected independently from one another from the group formed by: - C １ ~C ６ Alkyl, - C ２ ~C ６ alkenyl, - C ２ ~C ６ Alkynyl, - C ３ ~C ６ cycloalkyl, - phenyl, and - C ５ ~C ７ Heteroaryl.

5. The substituent R of the conductive salt １ , R ２ , R ３ and R ４ at least one of which is substituted by at least one fluorine atom and / or at least one chemical group, said chemical group being １ ~C ４ Alkyl, C ２ ~C ４ Alkenyl, C ２ ~C ４ Rechargeable battery cell (20, 40, 101) according to any one of claims 1 to 4, characterized in that it is selected from the group formed by alkynyl, phenyl and benzyl.

6. The substituent R of the conductive salt １ , R ２ , R ３ and R ４ At least one of the following is CF ３ Group or OSO ２ CF ３ A rechargeable battery cell (20, 40, 101) according to any one of claims 1 to 5, characterized in that it is a group.

7. Rechargeable battery cell (20, 40, 101) according to any one of claims 1 to 6, characterized in that the conductive salt is selected from the group formed by: 【Chemistry 2】

8. A rechargeable battery cell (20, 40, 101) according to any one of claims 1 to 7, characterized in that the electrolyte contains at least one additive.

9. The additives of the electrolyte include 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 carbonate, sultones, cyclic and acyclic sulfonates, acyclic sulfites, cyclic and acyclic sulfinates, organic esters, inorganic acids, acyclic and cyclic alkanes (the acyclic and cyclic alkanes are 1 bar 10. The rechargeable battery cell (20, 40, 101) according to claim 8, characterized in that the halogen-containing compound is selected from the group formed by halogen-containing compounds (having a boiling point of at least 36°C at room temperature), aromatic compounds, halogenated cyclic and acyclic sulfonylimides, halogenated cyclic and acyclic phosphate esters, halogenated cyclic and acyclic phosphines, halogenated cyclic and acyclic phosphites, halogenated cyclic and acyclic phosphazenes, halogenated cyclic and acyclic silylamines, halogenated cyclic and acyclic halogenated esters, halogenated cyclic and acyclic amides, halogenated cyclic and acyclic anhydrides and halogenated organic heterocycles.

10. 10. The rechargeable battery cell (20, 40, 101) according to any one of claims 1 to 9, characterized in that the concentration of the amount of substance of the conductive salt is in the range of 0.01 mol / l to 10 mol / l with respect to the total volume of the electrolyte.

11. The electrolyte contains at least 0.1 moles of SO per mole of conductive salt. ２ A rechargeable battery cell (20, 40) according to any one of claims 1 to 10, characterized in that it comprises:

12. The rechargeable battery cell (20, 40, 101) according to any one of claims 1 to 11, characterized in that the rechargeable battery cell (20, 40, 101) has a cell voltage of at least 4.0 volts.

13. A rechargeable battery cell (20, 40, 101) according to any one of claims 1 to 12, characterized in that the active metal is: - alkali metals, - alkaline earth metals, - a metal from group 12 of the periodic table, or - Aluminum.

14. The positive electrode (23, 44) contains A as the active material (24). ｘ M' ｙ M” ｚ O ａ A rechargeable battery cell (20, 40, 101) according to any one of claims 1 to 13, comprising at least one compound having the composition: A is at least one metal selected from the group formed by alkali metals, alkaline earth metals, metals of group 12 of the periodic table of the elements or aluminum, M' is at least one metal selected from the group formed by the elements Ti, V, Cr, Mn, Fe, Co, Ni, Cu and Zn, M" is at least one element selected from the group formed by the elements of groups 2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13, 14, 15 and 16 of the Periodic Table of the Elements, x and y are each independent numbers greater than 0; z is a number greater than or equal to 0, and a is a number greater than 0.

15. The compound is Li ｘ Ni ｙ１ Mn ｙ２ Co ｚ O ａ 15. The rechargeable battery cell (20, 40, 101) of claim 14, characterized in that it has a composition: wherein x, y1, and y2 are each independently a number greater than 0, z is a number greater than 0, and a is a number greater than 0.

16. The compound is A ｘ M' ｙ M” １ ｚ１ M” ２ ｚ２ O ４ and M" １ is at least one element selected from the group formed by the elements of groups 2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13, 14, 15 and 16 of the Periodic Table of the Elements, and M" ２ 15. The rechargeable battery cell (20, 40, 101) according to claim 14, characterized in that: is phosphorus; z is a number equal to or greater than 0; and the value of z2 is 1.

17. 17. The rechargeable battery cell (20, 40, 101) according to any one of claims 1 to 16, characterized in that the positive electrode (23, 44) comprises at least one metal compound selected from the group formed by metal oxides, metal halides and metal phosphates.

18. 18. The rechargeable battery cell (20, 40) according to any one of claims 1 to 17, characterized in that the positive electrode (23, 44) comprises at least one metal compound having the chemical structure of a spinel, a layered oxide, a conversion compound or a polyanionic compound.

19. A rechargeable battery cell (20, 40, 101) according to any one of claims 1 to 18, characterized in that the negative electrode (22, 45) is an insertion electrode.

20. 20. The rechargeable battery cell (20, 40, 101) according to any one of claims 1 to 19, comprising at least one negative electrode (22, 45) and at least one positive electrode (23, 44) arranged in the housing (28) in an alternating stacked or wound configuration, the positive electrode (23, 44) and the negative electrode (22, 45) being electrically separated from each other by at least one separator (21, 13), respectively.

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