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 very important 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 for example the operation of mobile phones. However, there is also a demand for larger rechargeable battery cells for high energy applications, and for electric drive of vehicles, it is especially important to store large amounts of energy in the form of battery cells.

[0003] An important 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 is a metal whose ions in the electrolyte migrate to the negative or positive electrode during charging and discharging of the cell and there take part in electrochemical processes. The 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 active metal are also called lithium-ion batteries. It is possible to increase the energy density of the lithium-ion battery 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 formed as insertion electrodes. The term "insertion electrode" in the sense of the present invention is understood to be 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 take place 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 discharging of the lithium-ion battery, the reverse process takes place.

[0005] The electrolyte is also an important functional element for a rechargeable battery cell. The electrolyte usually comprises a solvent or a mixture of solvents and at least one conductive salt. For example, a solid electrolyte or an ionic solution does not comprise a solvent and only comprises the conductive salt. 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 so that the charge transport between the electrodes, which is necessary for the functioning of the rechargeable battery cell, can be carried out by ionic conduction. The electrolyte is electrochemically decomposed oxidatively above a certain upper cell voltage limit of the rechargeable battery cell. This process often leads to irreversible destruction of the electrolyte components and thus to the failure of the rechargeable battery cell. Reductive processes can also destroy the electrolyte below a certain lower cell voltage limit. To avoid this process, the positive and negative electrodes are selected such that the cell voltage is lower or higher 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 for example contain ethylene carbonate. The electrolyte LP57 with the composition 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 organic lithium ion battery.

[0007] Besides lithium hexafluorophosphate (LiPF6), 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, in JP 4306858 (hereinafter referred to as [V1]), conductive salts are described in the form of tetraalkoxy salts or tetraaryloxyborate salts, which may be fluorinated or partially fluorinated. In JP 2001-143750 (hereinafter referred to as [V2]), fluorinated or partially fluorinated tetraalkoxyborates and tetraalkoxyaluminates are mentioned 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. In this case, oxidative decomposition of the organic solvent and / or the conductive salt occurs at the surface of the positive electrode. The reaction heat formed during the decomposition and the gaseous products generated during this process are the cause of the subsequent so-called "thermal runaway" and thus the destruction of the organic lithium-ion battery. Most charging protocols for organic lithium-ion batteries use the 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 several organic lithium-ion batteries of different capacities are connected in series.

[0009] Organic lithium-ion batteries therefore have problems with regard to their own stability and operational safety during long-term use. Safety risks also arise in particular 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. In order to avoid such safety risks, further measures must be implemented. These include in particular very precise control of the charging and discharging processes of the organic lithium-ion battery and optimization of the battery structure. Furthermore, the organic lithium-ion battery contains components that melt during an unintended temperature increase, which can fill the organic lithium-ion battery with molten plastic. This avoids further uncontrollable temperature increases. However, these measures lead to increased production costs and increased volume and weight during the manufacture 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 provides for the use of sulfur dioxide (SO2)-based electrolytes in rechargeable battery cells instead of organic electrolytes. Rechargeable battery cells containing SO2-based electrolytes have a particularly high ionic conductivity. The term "SO2-based electrolyte" in the sense of the present invention is understood to mean an electrolyte which not only contains SO2 in low concentrations as an additive, but in which the ionic mobility of the conductive salt contained in the electrolyte and which carries out the charge transport is ensured at least partially, mostly or completely by SO2. SO2 thus serves as a solvent for said conductive salt. The conductive salt can form liquid solvate complexes with gaseous SO2, in which the SO2 is bound and the vapor pressure is significantly reduced compared to pure SO2. An electrolyte with a lower vapor pressure is produced. This type of SO2-based electrolyte has the advantage of being non-flammable compared to the aforementioned organic electrolytes. It is thus possible to eliminate safety risks resulting from the flammability of the electrolyte.

[0011] The choice of binder for the positive and negative electrodes is important, both in lithium-ion batteries with organic electrolytic solvents and in rechargeable battery cells with SO2-based electrolytes. The binder is intended to improve the mechanical and chemical stability of the electrodes. The formation of a surface layer on the negative electrode and the resulting surface capacity in the first cycle should be as small as possible to increase the service life of the battery cell. The binder must be stable with respect to the electrolyte used and must maintain its own stability over time, even if the active metal (i.e. lithium in the case of lithium-ion batteries) is deposited and comes into contact with the binder during possible malfunctions during charging and discharging cycles. If the binder reacts with the metal, it leads to a 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 in the rechargeable battery cell. As a result, problems arise during the operation of the rechargeable battery cell. An important aspect in the selection of the binder is the shape of the conductor element. The conductor elements can be formed in planar form, for example in the form of a thin metal sheet or thin metal foil, or in three-dimensional form in the form of a porous metal structure, for example in the form of 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 elements, the active material is applied to the front and / or rear surface of the planar conductor element. Depending on the shape of the conductor element, there are different requirements for the binder, for example, it must have 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 improving the 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 the investigation of graphite-based anodes with binders SBR / CMC or PVDF in an organic electrolytic solvent (1 M) containing LiPF6 as a conductive salt in ethylene carbonate (EC) / diethyl carbonate (DEC) (v / v=1:1). They obtain the results that the electrodes with PVDF binder have lower resistance, better discharge rate and better cycling stability compared to electrodes with SBR / CMC binder mixtures.

[0013] US 2015 / 0093632 A1 (hereinafter referred to as [V4]) shows an SO2-based electrolyte with the composition LiAlCl4*SO2. The electrolyte preferably contains lithium tetrahaloaluminate, particularly preferably lithium tetrachloroaluminate (LiAlCl4), as a conductive salt. The positive and negative electrodes have conductor elements with an exceptionally thick and three-dimensional porous metal structure. 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 structural units of conjugated carboxylic acids, such as lithium polyacrylate (LiPAA), or of alkali metal, alkaline earth metal or ammonium salts of the conjugated carboxylic acids, or a combination thereof, or a binder B consisting of a polymer based on monomeric styrene and butadiene structural units, or a mixture of binders A and B.

[0014] WO 2020 / 221564 (hereinafter referred to as [V5]) also discloses an SO2-based electrolyte, in particular with LiAlCl4 as conductive salt, in combination with a sulfur-doped active material of the positive electrode. As binders for the negative and positive electrodes, which preferably have a conductor element with a three-dimensional porous metal structure, fluorinated binders such as, for example, vinylidene fluoride (THV) or polyvinylidene fluoride (PVDF), polyacrylates such as, for example, lithium polyacrylate (LiPAA), binders consisting of polymers based on monomeric styrene and butadiene structural units or binders based on carboxymethylcellulose, etc. are proposed. For the negative electrode, in particular, polymers of alkaline acids of conjugated carboxylic acids have been found to be particularly useful. For the positive electrode, in particular, THV and PVDF have been found to be particularly useful.

[0015] A particular drawback of the SO2-based electrolyte is that the hydrolysis products produced in the presence of possible traces of residual water can react with the cell components of the rechargeable battery cell, leading to the formation of undesirable by-products, and therefore care must be taken when manufacturing such rechargeable battery cells using SO2-based electrolytes 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, for example: 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 (LiTFSL), 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, there is at best low conductivity, insufficient for useful operation of a rechargeable battery cell. [Prior art documents] [Patent documents]

[0019] [Patent Document 1] Patent No. 4306858 [Patent Document 2] JP 2001-143750 A [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 application and properties of rechargeable battery cells containing 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, is such that: - 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 the formation of the surface layer; - has a binder which allows the production of electrodes with good mechanical stability, - having a binder that can be uniformly distributed or applied onto 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; - the electrolyte has good wettability with 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, where the surface capacity should be low and no further reductive electrolytic decomposition of the negative electrode occurs during subsequent operation; - has a SO2-based electrolyte with good solubility of conductive salts, which is a good ionic conductor and electronic insulator, thus facilitating ionic 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 housing materials; - Robust against electrical, mechanical or thermal abuse; - Improved electrical performance data, especially high energy density, - Improved overcharge and deep discharge properties as well as lower self-discharge properties; and - Longer service life, especially a higher number of available charge / discharge cycles.

[0022] Rechargeable battery cells of this kind should have in particular very good electrical energy and performance data, high operational stability and service life, in particular a high number of available charge / discharge cycles, while ensuring that the electrolyte is not 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, which comprises 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 comprise 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 the carboxymethyl cellulose group.

[0025] During the development of the battery cell according to the invention, the Applicant was faced with a number of difficult problems linked to the use of an SO2-based electrolyte and the use of planar conductor elements. In order to distribute the active material with the respective binder or combination of binders as uniformly as possible on the planar conductor element, it must be possible to produce a homogeneous mixture of the components with the solvent. The homogeneous mixture must be easily applied on the planar conductor element. If this condition is not met, significant problems arise in the production of mechanically stable electrodes. In the case of the rechargeable battery cell according to the invention, this problem was eliminated, since a homogeneous mixture was produced with the active material together with the first and second binders, which could be easily applied on the planar conductor element of the respective electrode. As the first binder, in particular styrene butadiene rubber can be used (English: Styrene butadiene rubber, abbreviated as SBR). As the second binder, in particular carboxymethylene cellulose (abbreviated as CMC) is used.

[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. approximately two-dimensional embodiment.

[0027] The SO2-based electrolyte used in the rechargeable battery cell of the present invention does not only contain SO2 as an additive in low concentrations, but also in a concentration in which the ionic mobility of the conductive salt contained in the electrolyte and responsible for the charge transport is at least partially, mostly or completely ensured by SO2. The first conductive salt is dissolved in the electrolyte and has very good solubility in the electrolyte. The conductive salt can form a liquid solvate complex with gaseous SO2, in which SO2 is bound. In this case, the vapor pressure of the liquid solvate complex is significantly reduced compared to pure SO2, resulting in an electrolyte with a lower vapor pressure. However, it is also within the scope of the present invention that no vapor pressure reduction may occur during the preparation of the electrolyte according to the present invention, depending on the chemical structure of the first conductive salt. In the latter case, it is preferable to work at low temperature or under pressure during the preparation of the electrolyte according to the present invention. The electrolyte may also contain several conductive salts, the chemical structures of which differ from one another.

[0028] A rechargeable battery cell having this type of electrolyte has the advantage that the first conductive salt contained in the electrolyte has high oxidation stability, so that decomposition does not occur substantially at higher cell voltages. The electrolyte preferably exhibits oxidation 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, more preferably up to an upper potential of at least 4.4 volts, more preferably up to an upper potential of at least 4.6 volts, 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. Thus, when such an electrolyte is used in a rechargeable battery cell, there is no or very little electrolyte decomposition occurring within the working potential, i.e., in the range between the end-of-charge voltage and the end-of-discharge voltage of both electrodes of the rechargeable battery cell. As a result, the rechargeable battery cell according to the present invention can have an end-of-charge voltage of at least 4.0 volts, more preferably at least 4.4 volts, more preferably at least 4.8 volts, more preferably at least 5.2 volts, 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] Moreover, 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 of at least 4.0 volts, preferably up to a potential of 4.4 volts, further preferably up to a potential of at least 4.8 volts, further preferably up to a potential of at least 5.2 volts, further preferably up to a potential of at least 5.6 volts and particularly preferably up 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 of the active metal during operation of the battery cell, where it is important that a good electrical connection of the active material to the planar conductor element of the positive electrode is not hindered by the binder of the positive electrode, 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 electrical connection 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 sense of the present invention is to be understood as a subcategory of the aforementioned intercalation materials. The intercalation compound acts 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 of the host matrix occur in the course of the 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 to be understood as 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. Upon acceptance and release of the ions of the active metal, structural changes occur in the matrix of the conversion compound.

[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 aluminium, 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 equal to or greater than 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 in the formula are represented by M' and M" respectively and represent the sum of metals and elements. For example, M' is two metals M' 1 and M' 2 In the case where the compound comprises a metal M', the index y is y=y1+y2, and y1 and y2 are each independently selected from the group consisting of a metal 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 = 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 the metal M", for the index z, z=z1+z2, and z1 and z2 are each independently selected from the group consisting of the metal M" 1 and Lin (M 2 The indices x, y, z and a must be selected 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 z2 = 1 x Fe y Mn z1 P z2 O4. In other compositions, M" is two nonmetallic compounds, e.g. M" 1 Fluorine as 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, the metals of the formula Li x Ni y1 Mn y2 Co z Lithium with the composition O2(NMC), i.e., 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 such a compound, it is possible to produce 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 lithium- and manganese-rich metal oxide (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 (Mn) in the 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 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 holds. 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 lithium- and manganese-rich metal oxide can also be represented by the formula mLi2MnO3(1 - m)LiM’O2 where 0 < m < 1. An example of this type 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's 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. The LiCoMnO4 has a structure similar to that of 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. 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 which is a conversion compound, which upon receiving an active metal, for example lithium or sodium, undergoes a solid-state redox reaction, 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 Lil.

[0041] In another advantageous development, the compound is 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 the formula 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 An example of lithium manganese ferrophosphate is Li(FePO4). 0.3 Mn 0.7 An example of lithium manganese phosphate is Li(Fe 0.3 Mn 0.7 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 at least one of the aforementioned compounds or combinations of compounds as active materials, by which is meant a positive electrode comprising at least two of the aforementioned materials.

[0045] The battery cell according to the invention comprises a positive electrode with a planar conductor element. This means that the positive electrode comprises a conductor element in addition to the active material. The conductor element is used to enable the required electronically conductive connection of the active material of the positive electrode. To that 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-like 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, the thin metal foil or the metal-coated plastic foil. The active material may be applied to the front and / or rear side of the planar conductor element. A planar conductor element of this kind 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 for 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 furthermore 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 of 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 It 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 It 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 the second binder, said further binder being preferably: 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 the alkali metal, alkaline earth metal or ammonium salts of said conjugated carboxylic acids, or combinations thereof.

[0048] The further binder in the form of a polymer may be lithium polyacrylate (LiPAA). The positive electrode may also have two further 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 (abbreviated PVDF) and / or a terpolymer formed by 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 of alkali metal, alkaline earth metal or ammonium salts of said conjugated carboxylic acids, or a combination thereof. When using said fluorinated binders, there is the problem that they are only soluble in organic solvents, which are often highly flammable and harmful to the environment. When producing a positive electrode with fluorinated binders, it is necessary to use complex equipment that takes into account the use of said solvents. In particular, explosion protection, environmental protection and protection of staff from exposure to explosion are problems here. These problems had to be taken into account by the applicant when developing an advantageous development of the battery cell according to the invention.

[0049] During the development of the rechargeable battery cell of the present patent application, the Applicant found that it was difficult to determine the optimal concentration of said first, second, third and / or fourth binders with respect to the total weight of the positive electrode: too low a concentration in the positive electrode leads to poor handling of the produced positive electrode, for example because an electrode without binder has no adhesion to the conductor element, which may lead to particle release of active material and, as a result, the produced rechargeable battery cell may be unusable. A too high concentration of binder also has a negative effect on the energy density of the rechargeable battery cell, since the energy density is reduced by the weight of the binder. Furthermore, a too high binder concentration leads to poor 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%, more preferably at most 10 wt%, more preferably at most 7 wt%, more preferably at most 5 wt%, more preferably at most 2 wt%, more preferably at most 1 wt% and particularly preferably at most 0.5 wt% with respect 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 particularly preferably in the range of 0.5 wt% to 5 wt%. Such concentrations allow 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 with SO2-based electrolytes are described.

[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 aluminium; - 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, - The central atom Z is aluminum or boron.

[0052] In the sense of the present invention, "C1-C 10 The term "alkyl" comprises linear or branched saturated hydrocarbon groups having from 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] In the sense of the present invention, "C2-C 10 The term "alkenyl" comprises unsaturated linear or branched hydrocarbon radicals having 2 to 10 carbon atoms, said hydrocarbon radical 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] In the sense of the present invention, "C2-C 10 The term "alkynyl" comprises unsaturated linear or branched hydrocarbon radicals having from 2 to 10 carbon atoms, said hydrocarbon radical 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] In the sense of the present invention, "C3-C 10 The term "cycloalkyl" comprises cyclic saturated hydrocarbon groups having from 3 to 10 carbon atoms, including in particular cyclopropyl, cyclobutyl, cyclopentyl, cyclohexyl, cycloheptyl, cyclohexyl, cyclononyl and cyclodecanyl.

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

[0057] In the sense of the present invention, "C5-C 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 tetrahalogenaluminate 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; alkenyl radicals from C2 to C6 alkenyl, preferably C2 to C4 alkenyl, particularly preferably ethenyl and propenyl, - 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 linear or branched saturated hydrocarbon groups 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, 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 cyclic saturated hydrocarbon groups 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 order to improve the solubility of the first conductive salt in an SO2-based electrolyte, 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. Said 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 atoms and / or said chemical groups.

[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 besides 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, which may be vinylene carbonate and its derivatives, vinyl ethylene carbonate and its derivatives, methyl ethylene 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 (such 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 phosphates, 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 embodiment 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 mentioned above, the electrolyte can contain not only one of the first conductive salt and one of the second conductive salt, but also a plurality of first conductive salts and a plurality of second conductive salts. In the latter case, the above-mentioned ratio includes a plurality of first conductive salts and a plurality of second conductive salts. The substance concentration of the first conductive salt is in the range of 0.01 mol / l to 10 mol / l, preferably 0.05 mol / l to 10 mol / l, more preferably 0.1 mol / l to 6 mol / l and particularly preferably 0.2 mol / l to 3.5 mol / l with respect to the total volume of the electrolyte.

[0073] In another preferred development of the rechargeable battery cell according to the invention, the electrolyte comprises at least 0.1 mol SO2 per mole of conductive salt, preferably at least 1 mol SO2, more preferably at least 5 mol SO2, more preferably at least 10 mol SO2 and particularly preferably at least 20 mol SO2. The electrolyte can also comprise a very high molar ratio of SO2, with a preferred upper limit of 2600 mol SO2 per mole of conductive salt, with upper limits of 1500, 1000, 500 and 100 mol SO2 per mole of conductive salt being preferred in that order. The term "per mole of conductive salt" refers to all conductive salts contained in the electrolyte. SO2-based electrolytes with this type of concentration ratio between SO2 and the conductive salt have the advantage that they are capable of dissolving a larger amount of conductive salt than electrolytes known from the prior art, for example based on organic solvent mixtures. Surprisingly, within the scope of the present invention, an electrolyte having a relatively small conductive salt concentration has been found to be advantageous, in spite of the associated increase in vapor pressure, particularly with regard to its stability over multiple charge / discharge cycles of the rechargeable battery cell. The SO2 concentration in the electrolyte affects the conductivity of the electrolyte. Thus, by selecting the SO2 concentration, the conductivity of the electrolyte 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 more than 50 weight percent (wt%) of the weight of the electrolyte, preferably more than 60 wt%, more preferably more than 70 wt%, more preferably more than 80 wt%, more preferably more than 85 wt%, more preferably more than 90 wt%, more preferably more than 95 wt% or even more preferably more 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 more preferred values ​​being 20 wt% SO2, 40 wt% SO2 and 60 wt% SO2. The electrolyte may contain up to 95 wt% SO2, with maximum values ​​of 80 wt% SO2 and 90 wt% SO2 being preferred in that order.

[0075] It is also within the scope of the present invention that the proportion of at least one organic solvent in the electrolyte is low or absent. The proportion of organic solvent in the electrolyte, for example in the form of a solvent or a mixture of organic solvents, may be at most 50 wt% of the weight of the electrolyte. 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 weight of the electrolyte. It is further preferred that the electrolyte is free of organic solvents. With a low or no proportion of organic solvents, the electrolyte has little or no flammability. This 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 is 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 metals are described below:

[0078] In an advantageous development of the rechargeable battery cell, the active metal is: - an alkali metal, in particular lithium or sodium, - alkaline earth metals, especially calcium, - metals of group 12 of the periodic table, in particular 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 comprises an insertion material as active material, in which ions of the active metal can be stored 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 lithium-based conductive salts, 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 comprises carbon, in particular modified graphite, as active or insertion material. However, it is also within the scope of the invention that the carbon is in the form of natural graphite (flaky 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, 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 which forms an alloy with lithium, for example metals and metal alloys which 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 impede good electrical connection of any one of the active materials to the planar conductor element of the negative electrode. The use of the first and second binders provides 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, with a porosity of preferably at most 50%, more preferably at most 45%, more preferably at most 40%, more preferably at most 35%, more preferably at most 30%, more preferably at most 20% and particularly preferably at most 10%. The porosity refers to the void volume relative to the total volume of the negative electrode, the void volume being formed by so-called pores or voids. The porosity results in an increase in the internal surface of the negative electrode. Furthermore, the porosity reduces the density of the negative electrode and thus also its weight. The individual pores of the negative electrode can preferably be completely filled by the electrolyte during operation.

[0086] In the battery cell according to the invention, the negative electrode has a planar conductor element. This means that the negative electrode also comprises 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-like 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 rear of the planar conductor element. Planar conductor elements of this kind have 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 side of the negative electrode is preferably at least 0.5 mAh / cm when a planar conductor element is used. 2 and furthermore 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 loading of the electrode with respect to the coating on one side, 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 It is.

[0087] In another advantageous development of the battery cell, the negative electrode comprises at least one further binder different from the first and the second binders, said further binder being 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 the alkali metal, alkaline earth metal or ammonium salts of said conjugated carboxylic acids, or combinations thereof.

[0088] The further binder in the form of a polymer may be lithium polyacrylate (LiPAA). The negative electrode may also have two further 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 PVDF) and / or a terpolymer formed by 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 of alkali metal, alkaline earth metal or ammonium salts of said conjugated carboxylic acids, or a combination thereof.

[0089] The use of said fluorinated binders poses the problem that they are often only soluble in organic solvents, which are highly flammable and harmful to the environment. The manufacture of the negative electrode with fluorinated binders requires the use of complex equipment that takes into account the use of said solvents. In particular, explosion protection, environmental protection and protection of staff from exposure to radiation are problems here. This problem had to be taken into account by the applicant when developing the advantageous development of the battery cell according to the invention. During the development of the rechargeable battery cell of the present patent application, the applicant discovered that it was difficult to determine the optimum concentration of said binder with respect to the total weight of the negative electrode: too low a concentration in the negative electrode leads to poor handling of the produced negative electrode, for example because an electrode without binder does not have adhesion to the conductor element, which leads to particle release of active material, which may result in the produced rechargeable battery cell being unusable. A too high concentration of the binder also has a negative effect on the energy density of the rechargeable battery cell, since the weight of the binder reduces the energy density. Furthermore, a too high binder concentration leads to poor wettability of the negative electrode with the 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%, more preferably at most 10 wt%, more preferably at most 7 wt%, more preferably at most 5 wt%, more preferably at most 2 wt%, more preferably at most 1 wt% and particularly preferably at most 0.5 wt% relative to 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%. The aforementioned concentrations allow good wettability 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 a low weight, a 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 are explained below with respect to its structure:

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

[0092] However, the rechargeable battery cell may also be formed as a coil cell, in which the electrodes are formed as thin layers wound with a separator material. The separator, on the one hand, spatially and electrically separates the positive and negative electrodes, and on the other hand, is permeable, inter alia, to the ions of the active metal. This creates a large electrochemically effective surface, which allows a correspondingly high current yield. The separator can be formed using nonwovens, membranes, wovens, knits, organic materials, inorganic materials or combinations thereof. Organic separators can consist, for example, of unsubstituted polyolefins (e.g. polypropylene or polyethylene), partially to fully halogen-substituted polyolefins (e.g. partially to fully fluorinated, in particular 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 a suitable 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 also be folded in the housing of the rechargeable battery cell, for example in a so-called "Z-fold" shape. In the case of the Z-fold, 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 a 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 negative electrode may be covered by 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 ensures uniform ion migration and distribution in the rechargeable battery cell. The more uniform the ion distribution, especially in the negative electrode, the greater the possible loading of active material in the negative electrode and, therefore, the greater the usable capacity of the rechargeable battery cell. At the same time, the risk of non-uniform loading and the resulting precipitation of the active metal is avoided. This advantage is particularly evident when the positive electrode of the rechargeable battery cell is covered by the coating.

[0095] The surface dimensions of the electrode and the coating are preferably coordinated with one another such 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] The surface area of ​​the coating may preferably 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 a further advantageous embodiment of the rechargeable battery cell according to the invention, the negative electrode has a coating whereas the positive electrode has no 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 description 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; [Diagram 2] FIG. 2 is a detailed view of the first embodiment example according to FIG. 1; [Diagram 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. 11 is an exploded view of a third example embodiment of a rechargeable battery cell according to the present invention. [Diagram 5] FIG. 1 shows the potential (in [V]) of 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, as a function of capacity relative to the theoretical capacity of the negative electrode. [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 having different binder combinations and planar conductor elements, with electrodes filled with electrolyte 1 of 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 different binder combinations and planar conductor elements. [Figure 9] FIG. 1 shows the potential (in [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 with respect to the theoretical capacity of the negative electrode. [Figure 10] FIG. 1 shows the discharge capacity as a function of cycle number for a two coil cell 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 with respect to the theoretical capacity of the negative electrode. [Figure 12] FIG. 1 shows the potential course (in [V]) during discharge as a function of the charge rate for 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 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. 2 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 PREFERRED EMBODIMENTS

[0100] FIG. 1 shows a cross-sectional view of a first embodiment of a rechargeable battery cell 20 according to the invention. This embodiment shows an electrode unit with 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 on which is applied on both sides 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 likewise has a conductor element 27 in the form of a planar metal foil on which is applied on both sides a homogeneous mixture of the active material 25 of the negative electrode 22, a first binder SBR and a second binder CMC. Alternatively, it is also possible to coat only one side of the planar conductor element of the edge electrode, i.e. the electrode that closes the electrode stack, with the active material. 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 a planar metal foil used as the conductor elements 26, 27 of the positive and negative electrodes 23, 22, respectively, in the second embodiment of Figure 1. The metal foil has a perforated or mesh-like structure with a thickness of 20 μm.

[0102] 3 shows an exploded view of a second embodiment of a rechargeable battery cell 40 according to the invention. This embodiment differs from the first embodiment in that the positive electrode 44 is covered by a coating 13 acting as a separator. The surface area of ​​the coating 13 is larger than that of the positive electrode 44, the boundary 14 of which is drawn in FIG. 5 by a dashed line. The two layers 15, 16 of the coating 13, which 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. Both 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 invention. The important structural elements of the battery cell 101 are shown, with a rolled electrode unit. The electrode unit 105 is formed by rolling a sheet of starting material in a cylindrical housing 102 with a cover part 103. The sheet consists of several layers, including one positive electrode, one negative electrode and a separator stretching between the electrodes, which electrically and mechanically isolates the electrodes from each other but is sufficiently porous or ionically conductive to allow the necessary ion exchange. The positive electrode has a conductor element in the form of a planar metal foil on both sides of which is applied 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 likewise comprises a conductor element in the form of a planar metal foil on which a homogeneous mixture of the active material 25 of the negative electrode 22, the first binder SBR and the second binder CMC is applied on both sides.

[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 via corresponding terminal lugs 106 for the positive pole and 107 for the negative pole with terminal connections 108 for the positive pole and 109 for the negative pole, thereby allowing electrical connection of the rechargeable battery cell 101. As an alternative to the electrical connection of the negative pole via the terminal lugs 107 and the terminal connection 109 as shown in FIG. 4, the electrical connection of the negative pole can also be made via the housing 102.

[0105] Example 1: Preparation of an example embodiment of a 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 (hereafter 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 escaping gases so that the molar ratio of AlCl3:LiCl:Al was 1:1.06:0.35. The mixture was then heat-treated in stages to produce a molten salt. After cooling, the formed molten salt was filtered, then cooled to room temperature and finally SO2 was added until the desired molar ratio of SO2 to LiAlCl4 was formed. The electrolyte thus formed has the composition LiAlCl4*xSO2, where x depends on the amount of SO2 added. In the experiments, the 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 synthesized 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 formulas shown below:

[0110] [ka]

[0111] For purification, the compounds 1, 2, 3, 4 and 5 were first recrystallized to remove any residual educt LiAlH4 from the first conductive salt, which may 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. It was found that compounds 1, 2, 3, 4 and 5 have good solubility in SO2.

[0113] The electrolytes 1, 2, 3, 4 and 5 are prepared according to the following methods: Steps 1 to 4 were followed 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) Liquid SO2 is injected, 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 0.6 mol / l (substance amount concentration per 1 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 are rechargeable battery cells with two negative electrodes and one positive electrode, each separated by a separator. The positive electrode had an active material, a conductive additive and two binders. The negative electrode contained graphite as an active material as well as two binders. The negative electrode may further have a conductive additive, as described in the experiments. The active material of the positive electrode is described in each experiment. In particular, the purpose of the experiments is 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 invention. Table 2a shows the binders investigated. Table 2b shows 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. For each experiment, multiple identical experimental complete cells were usually prepared, i.e., two to four, 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. The surface layer is formed on the negative electrode during the first charge of the experimental full cell. The surface layer formation consumes lithium ions irreversibly (surface capacity), which reduces the cyclable capacity available for the experimental full cell in subsequent cycles. The surface capacity (unit [%]) relative to the theoretical value used to form the surface layer on the negative electrode is calculated by the following formula:

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

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

[0123] Discharge capacity: In the measurement of an experimental complete cell, for example, the discharge capacity is determined by the number of cycles. For this purpose, the experimental complete cell is charged to a predetermined upper potential limit at a predetermined charging current. The corresponding upper potential limit is held until the charging current drops to a certain value. Then, discharging is performed at a predetermined discharging current until a predetermined discharging potential is reached. This charging method is called I / U charging. The process is repeated for the desired number of cycles.

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

[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 indicate the voltage / potential that a cell or battery must reach when being charged by a battery charging device.

[0126] Charging of the battery is preferably performed at a current rate of C / 2 and a temperature of 22° C. By definition, at a charge / discharge rate of 1C, the nominal capacity of the cell is charged / discharged in one hour, so a current rate of C / 2 means a charging time of two hours.

[0127] The term "discharge potential" is used synonymously 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 charging device.

[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 the experiment and is 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 Rechargeable battery cells with SO2-based electrolyte according to the prior art use electrodes with three-dimensional conductive elements, mainly consisting of, for example, nickel foam (see [V5]). The preferred binder for the negative electrodes 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 conductive elements in the form of nickel foam, as known from the prior art. The binder combinations were: 2wt% LiPAA / 2wt% CMC, 2wt% LiPAA / 2wt% 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 combination of binder in the negative electrode. All three experimental complete cells were filled with lithium tetrachloroaluminate electrolyte according to Example 1, with the composition LiAlCl4*6SO2.

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

[0133] For this purpose, the experimental complete cell was equipped with a 125mAh (Q ladThe experimental complete cell was then discharged at 15 mA until a potential of 2.5 volts was reached. The discharge capacity (Q 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: NEL2%SBR / 2%CMC: 7.48% of theoretical value of negative electrode NEL 2% LiPAA / 2% CMC: 7.15% of theoretical value of negative electrode NEL 2% LiPAA / 2% SBR: 9.34% of theoretical value of 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 potential of 3.6 volts 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 uniform, slightly 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 show 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 impact 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, values ​​of the adhesion of the electrode material to the planar conductor elements were determined, and on the other hand, values ​​of the loading, i.e. 1 cm 2 An investigation was carried out 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 a tensile and compression tester model T1000 from MFC Sensor Technik. The test was a 90° peel test. The peel test is used to check the properties of the foil connected to the substrate in a tensile test. The coated foil under investigation was fixed on a carrier plate and the free end was fixed in the tensile tester and pulled upwards at a constant speed of 100 mm / min. During this, the planar conductor element in the form of the conductor element foil peeled off from the electrode layer and the adhesion along the electrode foil was recorded. The tests were carried out on two graphite electrodes with binder CMC-LiPAA-SBR (1%-2%-1%) on metal foil as planar conductor element (electrode 1) and binder CMC-SBR (2%-1%) (electrode 2) as planar conductor element. Table 3 shows the results of the adhesion measurements.

[0143] [Table 3]

[0144] Graphite with a binder combination containing a LiPAA proportion shows significantly lower adhesion values ​​compared to graphite with a binder combination without a LiPAA proportion, which means that in electrode 1 the graphite adheres less well to the conductor element and mechanical loads during operation of the battery cell may cause chipping of the electrode material, whereas electrodes with a CMC / SBR binder combination show good adhesion to planar conductor elements.

[0145] Possible filling volume of a planar conductor element, i.e. 1 cm 2 The amount of active material per electrode surface was investigated. To produce planar electrodes, 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 is necessary to remove the solvent from the electrode. After cooling, the electrode was compressed using a calender.

[0146] Binder mixtures consisting of LiPAA (2 wt%) and CMC (2 wt%) on the one hand and SBR (2 wt%) and CMC (2 wt%) on the other hand were prepared. Due to the poor mechanical properties of LiPAA on planar electrodes, a binder mixture of approximately 5 mg / cm on metal foils was prepared. 2 Only 14 mg / cm2 of graphite / binder could be applied. When using an SBR / CMC binder mixture, 14 mg / cm2 2 It was possible to apply a desired amount of 0.1% to 0.1% of the total weight of the electrode. To produce electrodes with high loadings and therefore high capacity, the SBR / CMC binder combination is suitable.

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

[0148] Graphite electrodes containing PVDF were also investigated, since it has been suggested as a suitable binder in the prior art (see [V3] and [V5]). First, the surface capacity was measured. For this, half-cells were charged at a rate of 0.1 C to a potential of 0.03 V and discharged at the same rate to a potential of 0.5 V. The capacity loss of 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 %) with respect to 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 theoretical value of negative electrode NEL 2%SBR / 2%CMC: 14.0% of theoretical value of negative electrode NEL 2.0 to 4.0wt% PVDF: 21.5% of theoretical value of negative electrode

[0150] The surface capacity of the negative electrode with PVDF binder is very high at 21.5%, which means that almost a quarter of the battery capacity is already used for the 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), in cycles 1 to 5, the half-cells with SBR / CMC binder 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 volts. From cycle 6, the charge / discharge rate was increased to 1 C. During further charging, the potential of 0.03 volts was maintained 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 (units [% of nominal capacity]). Both half-cells have a stable discharge capacity profile. The combination of SBR and CMC binder in SO2-based electrolyte is very 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, a 0.9 Ah (Q lad The coil cell was then 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 (in [V]) of various coil cells during charging of the negative electrode as a function of the capacity (in [%]) relative to the theoretical capacity of the negative electrode. The surface capacity (in [% of the theoretical capacity of the negative electrode]) obtained was about 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 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 (units [% of nominal capacity]).

[0158] Both coil cells have a uniform, slightly decreasing profile. The combination of SBR and CMC binder is also well suited for coil cells with SO2-based electrolyte 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 capacitances of electrolytes 1 and 3 and of lithium tetrachloroaluminate electrolyte were determined and on the other hand the discharge capacities in 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 active material.

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

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

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

[0166] FIG. 13 illustrates the conductivity of electrolytes 1 and 4 depending on the concentration of compound 1 or 4. A maximum conductivity of about 37.9 mS / cm is found for electrolyte 1 with a concentration of compound 1 between 0.6 mol / L and 0.7 mol / L. In comparison, organic electrolytes known from the prior art, such as LP30 (1M LiPF6 / EC-DMC (1:1 by weight)), only have a conductivity of about 10 mS / cm. For electrolyte 4, a maximum of 18 mS / cm is obtained for a conductive salt concentration of 1 mol / L.

[0167] FIG. 14 illustrates the conductivity of electrolytes 3 and 5 depending on the concentration of compounds 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 shows a maximum conductivity of 0.5 mS / cm when the conductive salt concentration is 0.6 mol / L. Although the conductivity of electrolytes 3 and 5 was low, it was sufficient to allow charging or discharging, 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 measure the low temperature behavior of the electrolyte 1 in comparison with the lithium tetrachloroaluminate electrolyte, two experimental complete cells were prepared according to Example 2. One experimental complete cell was filled with the lithium tetrachloroaluminate electrolyte having the composition 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 active material, and the experimental cell containing electrolyte 1 contained lithium nickel manganese cobalt oxide (NMC) as the positive active material. The experimental complete cells were charged to 3.6 volts (LEP) or 4.4 volts (NMC) at 20°C and discharged again to 2.5 volts at each investigated temperature. The discharge capacity reached at 20°C was evaluated as 100%. The temperature for discharge was reduced in temperature steps of 10°K. The obtained discharge capacity was expressed as a percentage of the discharge capacity at 20°C. The low temperature discharge is largely independent of the positive and negative active materials used, so the results are applicable to all combinations of active materials. Table 5 shows the results.

[0170] [Table 5]

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

Claims

1. The SO 2 battery includes at least one positive electrode (23, 44) having an active metal, 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. 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 the carboxymethylcellulose group; The first conductive salt is - of formula (I) 【Chemistry 1】 having 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 aluminium, x is an integer from 1 to 3, the substituents R 1 , R 2 , R 3 and R 4 are independently of one another selected from the group formed by 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) comprises at least one further 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 first conductive salt １ , R ２ , R ３ and R ４ are selected independently of 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 first 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 A 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 first 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 base.

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

8. 8. The rechargeable battery cell (20, 40, 101) according to any one of claims 1 to 7, characterized in that the electrolyte comprises at least one second conductive salt different from the first conductive salt.

9. A rechargeable battery cell (20, 40, 101) according to any one of the preceding claims, characterized in that the electrolyte comprises at least one additive.

10. The additives of the electrolyte include vinylene carbonate and its derivatives, vinyl ethylene carbonate and its derivatives, methyl ethylene carbonate and its derivatives, lithium (bis oxalato) 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 9, 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.

11. The rechargeable battery cell (20, 40, 101) according to claim 8, claim 9 when relying on claim 8, or claim 10 when indirectly relying on claim 8, characterized in that the electrolyte has the following composition with respect 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; (iii) 0 to 25 wt % of said second conductive salt, and (iv) 0 to 10 wt % of said additive.

12. 12. The rechargeable battery cell (20, 40, 101) according to any one of claims 1 to 11, characterized in that the concentration of the quantity of substance of the first conductive salt is in the range of 0.01 mol / l to 10 mol / l with respect to the total volume of the electrolyte.

13. A rechargeable battery cell (20, 40) according to any one of the preceding claims, characterized in that the electrolyte contains at least 0.1 mole of SO2 per mole of conductive salt.

14. The rechargeable battery cell (20, 40, 101) according to any one of claims 1 to 13, characterized in that the rechargeable battery cell (20, 40, 101) has a cell voltage of at least 4.0 volts.

15. A rechargeable battery cell (20, 40, 101) according to any one of claims 1 to 14, characterized in that the active metal is: - alkali metals, - alkaline earth metals, - a metal from group 12 of the periodic table, or - Aluminum.

16. 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 15, 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 aluminium, 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 equal to or greater than 0, a is a number greater than 0.

17. The compound is Li ｘ Ni ｙ１ Mn ｙ２ Co ｚ O ａ 17. The rechargeable battery cell (20, 40, 101) according to claim 16, 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.

18. 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 17. The rechargeable battery cell (20, 40, 101) according to claim 16, characterized in that: is phosphorus, z is a number equal to or greater than 0, and z2 has a value of 1.

19. 19. The rechargeable battery cell (20, 40, 101) according to any one of claims 1 to 18, 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.

20. 20. The rechargeable battery cell (20, 40) according to any one of claims 1 to 19, 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.

21. The rechargeable battery cell (20, 40, 101) according to any one of the preceding claims, characterized in that the negative electrode (22, 45) is an insertion electrode.

22. The rechargeable battery cell (20, 40, 101) according to any one of claims 1 to 21, characterized in that it comprises at least one negative electrode (22, 45) and at least one positive electrode (23, 44) arranged in an alternating stacked or wound manner within the housing (28), 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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