Rechargeable battery cell with active electrode depolarizer

Abstract

The present invention provides a rechargeable battery cell comprising a housing (1), at least one positive electrode (4), at least one negative electrode (5) and a sulfur dioxide-based electrolyte as an active electrode depolarizer; wherein the positive electrode (4) comprises carbon and has a thickness of at least 0.2 mm, preferably a thickness of at least 0.4 mm, more preferably a thickness of at least 0.6 mm, more preferably a thickness of at least 0.8 mm, more preferably a thickness of at least 1.0 mm, more preferably a thickness of at least 1.5 mm, more preferably a thickness of at least 2.0 mm and most preferably a thickness of at least 4.0 mm.

Description

Technical Field

[0001] The present application relates to a rechargeable battery cell comprising a sulfur dioxide (SO2)-based electrolyte as an active electrode depolarizer. The battery cell has a housing, at least one positive electrode and at least one negative electrode. Background Art

[0002] Rechargeable battery cells are of great importance in many areas of technology. They are often used in applications requiring relatively low currents, such as mobile phones. However, they are also in high-current applications, where high-capacity energy storage is crucial.

[0003] A key property of a rechargeable battery cell is its energy density. Ideally, a rechargeable battery cell should contain as much electrical energy as possible per unit weight and volume. As an active metal, lithium has proven particularly advantageous for this purpose. The active metal of a rechargeable battery cell is a metal whose ions in the electrolyte migrate to the negative or positive electrode when the battery is charged or discharged and participate in the electrochemical processes there. These electrochemical processes directly or indirectly result in the release or absorption of electrons to or from an external circuit. Rechargeable battery cells containing lithium as the active metal are also known as lithium-ion batteries.

[0004] Both the positive and negative electrodes of lithium-ion batteries are designed as insertion electrodes. In the context of the present invention, the term "insertion electrode" refers to an electrode having a crystal structure in which ions of the active material can be stored or removed during operation of the lithium-ion battery. This means that electrode processes can occur not only on the surface of the electrode, but also within its crystal structure. The negative electrode of a conventional lithium-ion battery cell containing an organic electrolyte can contain, for example, a carbon coating applied to a conductive element (for example containing copper). The conductive element is a conductive material that provides the conductive connection required to create an external circuit. The positive electrode can include, for example, lithium cobalt oxide (LiCoO2) applied to an aluminum conductive element. Both electrodes can typically have a thickness of less than 100 μm, so both electrodes are typically very thin. When the lithium-ion battery is charged, ions of the active metal are removed from the positive electrode and stored in the negative electrode. When the lithium-ion battery is discharged, the opposite process occurs.

[0005] Ions are transported between the electrodes via an electrolyte, ensuring the required ion mobility. State-of-the-art lithium-ion batteries typically contain an electrolyte consisting of a conductive salt dissolved in an organic solvent or solvent mixture. The conductive salt is a lithium salt, such as lithium hexafluorophosphate (LiPF6). The solvent mixture can, for example, contain ethylene carbonate. Due to the organic solvent or solvent mixture, these lithium-ion batteries are also referred to as organic lithium-ion batteries.

[0006] Organic lithium-ion batteries may encounter problems with stability and long-term operational reliability. Safety risks are particularly caused by the flammability (i.e., flammability) of organic solvents or solvent mixtures. When organic lithium-ion batteries catch fire or even explode, the organic solvents of the electrolyte can form flammable substances. To avoid this safety risk, additional measures must be taken. These measures generally include high-precision regulation of the charging and discharging processes of organic lithium-ion batteries, as well as optimized battery design. In addition, organic lithium-ion batteries contain components that melt during unexpected temperature increases and fill the organic lithium-ion battery with molten plastic. This prevents further uncontrolled temperature increases. However, these safety measures lead to higher production costs for organic lithium-ion batteries and increase the volume and weight of organic lithium-ion batteries. They can also reduce the energy density of organic lithium-ion batteries.

[0007] The aforementioned stability and long-term reliability issues become even more problematic when developing battery cells for high-energy applications.

[0008] Some rechargeable batteries use sulfur dioxide (SO2)-based electrolytes instead of organic electrolytes. Rechargeable batteries including SO2-based electrolytes have high ionic conductivity because they can dissolve large amounts of conductive salts. In the context of this disclosure, the term "SO2-based electrolyte" is used to refer to an electrolyte that not only contains a low concentration of SO2 as an additive, but also has a concentration of SO2 sufficient to allow the movement of conductive salt ions included in the electrolyte, which are responsible for charge transport. Compared to the above-mentioned organic electrolytes, SO2-based electrolytes have the advantage of being non-flammable. Therefore, safety risks caused by the flammability of the electrolyte can be reduced or substantially eliminated.

[0009] EP2534719B1 provides an example of a rechargeable battery using SO2, which discloses a rechargeable battery cell having a housing, a positive electrode, a negative electrode and an electrolyte. The electrolyte of this rechargeable battery cell is based on SO2 and contains a conductive salt. The positive electrode active material that is at least partially responsible for the energy storage of the rechargeable battery cell may include a lithium metal oxide or a lithium metal phosphate, such as lithium iron phosphate (LiFePO4). Using this rechargeable battery cell, for example, a specific capacity of 155 mAh / g can be achieved at a 1C discharge rate. By definition, at a discharge rate of 1C, the nominal capacity of the battery is discharged in one hour.

[0010] In addition to rechargeable batteries containing an SO2-based electrolyte and lithium metal phosphate or lithium metal oxide as the positive electrode active material, there are also rechargeable batteries in which SO2 not only serves as an electrolyte but also, together with a conductive salt, serves as a reactive component, which can be referred to as an "active electrode depolarizer." In other words, the active electrode depolarizer consists of the SO2-based electrolyte, i.e., this component of the rechargeable battery cell. This means that the sulfur dioxide (SO2)-based electrolyte serves as the active electrode depolarizer. An active electrode depolarizer refers to SO2 in the electrolyte undergoing a reduction reaction during discharge, which in turn triggers one or more reactions in which one or more discharge products are formed and deposited on the positive electrode. Other components in the electrolyte may also undergo reduction reactions and / or other chemical reactions during discharge. During charging, one or more discharge products begin to disappear, and the reduced SO2 is oxidized back to its original state. Other components in the electrolyte may also be oxidized during charging. In this disclosure, rechargeable batteries in which SO2 not only serves as an electrolyte but is also reduced during discharge and reoxidized back to its original state during charging are referred to as "SO2-depolarizer cells." As used herein, "discharge products" refer to products formed by reactions that occur after SO2 and other components of the electrolyte are reduced during discharge. Therefore, SO2 depolarizer cells can eliminate or reduce the need for additional active materials, such as lithium metal phosphates or lithium metal oxides, at the positive electrode. This can improve the manufacturability of rechargeable battery cells and reduce production costs.

[0011] An example of an SO2 depolarizer cell is provided by Dey et al., "Inorganic Electrolyte SO2 Rechargeable System: Development of a Prototype Sealed C Cell and Evaluation of Its Performance and Safety Characteristics," J. Electrochem. Soc. 135, 2115-2120 (1988). The SO2 depolarizer cell reported by Dey et al., which uses an SO2-based electrolyte containing LiAlCl4·6SO2 in a C-sized rechargeable SO2 cell prototype, exhibits an energy density of 134 Wh / kg, with a theoretical capacity of the SO2-based electrolyte of approximately 144 mAh / g.

[0012] In order to expand the application possibilities of rechargeable batteries and improve their performance, the present invention aims to provide a battery cell that, compared with prior art rechargeable SO2 batteries, SO2 depolarizer batteries and organic lithium-ion batteries, exhibits;

[0013] - Good electrical performance data, especially high energy density and reduced self-discharge;

[0014] - extended service life, especially a high number of available charge and discharge cycles;

[0015] - Reduce total weight;

[0016] - Improved operational safety, including under more challenging conditions that may be encountered, such as a wide temperature range from extreme cold (e.g., -15°C) to extreme heat (e.g., 35°C), and potential battery damage that could lead to exposure of the battery contents to air and potential fire (e.g., from a car collision);

[0017] - reduced production costs in terms of the raw materials required and the production process, including compared to electrode materials that would otherwise be used, as the carbon required for the cathode is relatively cheap; and

[0018] - Improved stability under overcharge and deep discharge conditions.

[0019] One advantageous feature of the rechargeable SO2 depolarizer cells disclosed herein is the high conductivity of their SO2-based electrolyte (approximately 0.1 S / cm at room temperature). This excellent conductivity enables the rechargeable SO2 depolarizer cells to have good battery power ratings or performance, such as low resistance and fast charging capability.

[0020] The rechargeable battery cells described herein should also be suitable for high-energy applications. Within the meaning of the present disclosure, a rechargeable high-energy battery cell may have a specific capacity greater than 500 mAh / g, preferably greater than 750 mAh / g, and more preferably greater than 1000 mAh / g. The energy density of the high-energy battery may be 150 Wh / kg, preferably 300 Wh / kg, preferably 500 Wh / kg, more preferably 1000 Wh / kg, and most preferably 1500 Wh / kg.

[0021] In detail, the energy density described herein may be at least 150Wh / kg, at least 200Wh / kg, at least 250Wh / kg, at least 300Wh / kg, at least 500Wh / kg, at least 600Wh / kg, at least 700Wh / kg, at least 800Wh / kg, at least 900Wh / kg, at least 1000Wh / kg, about 1500Wh / kg or greater than 1500Wh / kg. Summary of the Invention

[0022] This technical problem is solved by a rechargeable battery cell having the characteristics disclosed in this specification. Advantageous embodiments and further developments are also disclosed in this specification.

[0023] In a first aspect of the present invention, a rechargeable battery cell comprises a housing, at least one positive electrode, at least one negative electrode, and a sulfur dioxide-based electrolyte as an active electrode depolarizer. The positive electrode comprises carbon and has a thickness of at least 0.2 mm. It preferably has a minimum thickness of 0.4 mm, more preferably 0.6 mm, more preferably 0.8 mm, more preferably 1.0 mm, more preferably 1.5 mm, more preferably 2.0 mm, and most preferably 4.0 mm.

[0024] In a second aspect of the present invention, a rechargeable battery cell further comprises a housing, at least one positive electrode, at least one negative electrode, and a sulfur dioxide-based electrolyte as an active electrode depolarizer. In addition to carbon, the positive electrode further comprises at least one other chemical element or compound containing the chemical element in the form of a metal oxide. This chemical element is selected from vanadium, nickel, copper, magnesium, manganese, titanium, aluminum, lead, palladium, tungsten, and chromium. The additional chemical element or compound containing the chemical element is present in the positive electrode in a concentration of 1 to 20 weight percent (wt%), preferably 5 to 15 wt%, based on the total weight of the carbon of the electrode.

[0025] In a third aspect of the present invention, a rechargeable battery cell further comprises a housing, at least one positive electrode, at least one negative electrode, and a sulfur dioxide-based electrolyte as an active electrode depolarizer. The positive electrode comprises a conductive element having a three-dimensional porous metal structure, particularly in the form of a metal foam. This porous metal structure extends over at least 70%, preferably at least 80%, and more preferably at least 90% of the thickness of the positive electrode.

[0026] Typically, a SO2 depolarizer cell includes a housing, at least one positive electrode, at least one negative electrode, and an SO2-based electrolyte. The SO2 depolarizer cell can have electrodes of the same or different thicknesses, for example, the cathode can have a different thickness than the anode, and / or the cathode can have different thicknesses, and / or the anode can have different thicknesses.

[0027] As described above, sulfur dioxide (SO2)-based electrolytes act as an active electrode depolarizer. SO2 acts as an active material and, therefore, directly participates in a redox reaction that can occur reversibly and repeatedly in a rechargeable battery cell. As described above, other components of the SO2-based electrolyte can also undergo reversible redox reactions. This reversible redox reaction can contribute to the good rechargeability and long-term stability characteristics of SO2-depolarizer cells.

[0028] Optionally, additional active materials may be introduced into the positive electrode, such as lithium metal phosphates or lithium metal oxides. However, eliminating or reducing the use of such materials may improve the manufacturability and reduce production costs of the SO2 depolarizer cells described herein. Therefore, the use of such materials may be avoided in the SO2 depolarizer cells described herein.

[0029] Active electrode depolarizer refers to an electrolyte that is essentially liquid in the depolarizer cell, but may contain solids. For example, during operation of a rechargeable battery cell, oxidation-reduction reactions occurring at the positive electrode may result in the formation of solid reaction products that may precipitate and / or deposit on or in the positive electrode. These solid reaction products deposited on the electrode may be deposited on the positive electrode surface in the form of a thin film or coating. As described above, in addition to providing SO2 that is reduced during discharge, SO2-based electrolytes also enable charge transport between electrodes and ensure ion mobility. To this end, the SO2-based electrolyte contains a sufficiently high SO2 concentration to enable ions in the conductive salt contained in the electrolyte to migrate and provide charge transport.

[0030] SO2 depolarizer cells may include a housing, at least one positive electrode, at least one negative electrode, an SO2-based electrolyte as an active electrode depolarizer, and one or more additional components that may facilitate and / or participate in reactions occurring during discharge and / or charge.

[0031] The SO2 depolarizer cell may comprise one or more components that catalyze the formation of one or more discharge products from the SO2-based electrolyte during discharge and / or the reformation of SO2 during charging. Where one or more catalytic components are required, the positive electrode may comprise carbon and one or more chemical elements (or compounds containing the chemical elements), typically in the form of metal oxides, which may act as a catalyst. The one or more catalytic chemical elements may comprise one or more metals selected from the group consisting of vanadium, nickel, copper, magnesium, manganese, titanium, aluminum, lead, palladium, tungsten, chromium, and combinations thereof. The additional chemical elements (or compounds containing the chemical elements) may be present in the positive electrode in a concentration of 0.01 to 20 weight percent (wt%), preferably 1 to 20 weight percent (wt%), and more preferably 5 to 15 wt% or more, based on the total weight of carbon in the electrode. Within these ranges are 0.01-1 wt%, 1-5 wt%, 2.5-7 wt%, 5-10 wt%, 7.5-12.5 wt%, 10-15 wt%, 12.5-17.5 wt%, 15-20 wt%, greater than 20 wt%. The additional chemical element or compound can act as a catalyst that supports or promotes redox reactions and / or other reactions of the SO2-based electrolyte components at the positive electrode, which can enhance one or more performance characteristics of the SO2 depolarizer cell. For example, the additional chemical element or compound that acts as a catalyst can be present as a coating on an electrode that can contain, for example, carbon. Alternatively, the additional chemical element or compound can form a mixture with the carbon used in the electrode. For example, in addition to carbon, the positive electrode can also include a known SO2 redox catalyst, such as vanadium oxide (V2O5). In such embodiments, vanadium oxide may be present in an amount from 1 to 5 wt%, from 2.5 to 7.5 wt%, from 5 to 10 wt%, from 7.5 to 12.5 wt%, from 10 to 15 wt%, from 12.5 to 17.5 wt%, from 15 to 20 wt%, greater than 20 wt%.

[0032] In some aspects, the SO2 depolarizer cell may include a positive electrode having a conductive element having a three-dimensional porous metal structure to provide an increased surface area value, such as a metal foam, a fleece-like fabric, a lattice, a matrix, or a grid. As used herein, the term "three-dimensional porous metal structure" refers to any structure made of metal having a height, length, and thickness, and including holes, pores, openings, lattices, orifices, cavities, or other orifices (collectively referred to as "pores"), which extend into the thickness of the electrode and optionally through the thickness of the electrode to form multiple surfaces compared to an electrode having the same external dimensions but with a flat surface (i.e., without such pores), which is used to increase the total surface area of the electrode. As described above, optionally, the pores of the three-dimensional porous metal structure can allow the electrolyte to pass completely through the electrode, which in turn can provide a favorable electrolyte flow through the battery. Optionally, the pores of the three-dimensional porous metal structure may not allow the electrolyte to pass completely through the electrode. The porous metal structure can comprise at least 10%, at least 20%, at least 30%, at least 40%, at least 50%, at least 60%, at least 70%, at least 80%, or at least 90% of the thickness of the positive electrode. The porous metal structure can comprise less than 80%, less than 70%, less than 60%, less than 50%, less than 40%, less than 30%, less than 20%, and less than 10% of the weight of the positive electrode, with lower weight percentages generally being advantageous because the balance of electrode weight can significantly benefit battery performance. In an SO2 depolarizer cell including an electrode containing a three-dimensional porous metal structure, the SO2 electrolyte can penetrate the pores of the three-dimensional porous metal structure, thereby partially or completely filling the pores. The conductive element ensures the necessary conductive connection of the SO2-based electrolyte and its reduction and oxidation products located in the pores and on the surface of the positive electrode. Therefore, including the three-dimensional porous metal structure conductive element can provide enhanced performance of the SO2 depolarizer cell compared to an SO2 depolarizer cell including an electrode without a three-dimensional porous metal structure.

[0033] In the case of employing such a three-dimensional porous metal structure, at least one additional electrode material such as carbon can be incorporated into the pores of the three-dimensional porous metal structure to help promote the oxidation-reduction reaction of the SO2-based electrolyte at the positive electrode. This additional electrode material can also be porous so that the SO2-based electrolyte can penetrate not only into the pores of the three-dimensional porous metal structure, but also into the pores of this additional electrode material, thereby providing an electrode with a larger surface area for the oxidation-reduction reaction of the SO2-based electrolyte that may occur. The amount of such additional electrode material provided in the three-dimensional porous metal structure of the electrode is referred to herein as the "loading" of the positive electrode, as discussed further below. Therefore, incorporating the porous additional electrode material into the three-dimensional porous metal structure increases the internal surface area of the conductive element, thereby increasing the available reaction surface for the reduction-oxidation reaction occurring at the positive electrode. Electrodes having three-dimensional porous metal conductive elements can allow for significant loading of the positive electrode, which in turn can increase the capacity of the battery.

[0034] positive electrode

[0035] Provided below are further details and additional features of a positive electrode that can be used with the SO2 depolarizer cell of the present disclosure. Although exemplary materials, dimensions, and other parameters are provided below to guide one of ordinary skill in formulating a positive electrode, the final formulation, materials, dimensions, quantity, location, and other parameters of the positive electrode will be determined based on the specific battery parameters and desired performance characteristics.

[0036] As described above, in embodiments, the positive electrode of the SO2 depolarizer cell has a conductive element comprising a three-dimensional porous metal structure, such as a metal foam, fleece-like fabric, lattice, matrix, or grid. Such a three-dimensional porous metal structure can provide additional surface area compared to an electrode comprising a smooth surface without pores. Metal foam is an example of a three-dimensional porous metal structure that can provide a large amount of surface area and is therefore contemplated as an electrode material that is potentially useful in all embodiments of the SO2 depolarizer cell described herein.

[0037] As also mentioned above, the electrodes can have a considerable thickness, ranging from 0.1 mm to 25 mm, preferably 0.2 mm to 20 mm, and greater than 25 mm. The electrodes preferably have a minimum thickness of 0.4 mm, more preferably 0.6 mm, more preferably 0.8 mm, more preferably 1.0 mm, more preferably 1.5 mm, more preferably 2.0 mm, and most preferably 4.0 mm. If thicker electrodes are desired, thicknesses of 10 to 20 mm, 12.5 to 17.5 mm, 14 to 16 mm, and approximately 15 mm can provide acceptable results. When the SO2 depolarizer cell has multiple positive electrodes, the electrodes can be of the same or different thicknesses.

[0038] As described above, at least one additional electrode material can be incorporated into the three-dimensional porous metal structure of the conductive element to catalyze the oxidation-reduction reaction and / or other reactions of the SO2-based electrolyte at the positive electrode. As described above, the additional electrode material can include carbon, which itself can also be porous. The carbon can be substantially uniformly distributed within the three-dimensional porous metal structure or within at least a portion of the three-dimensional porous metal structure. This enables the desired conductive connection of the carbon to be achieved through the conductive element. A substantially uniform distribution is achieved by substantially uniformly incorporating the carbon into the pores of the metal structure or at least within a portion of the pores of the three-dimensional porous metal structure. The amount of carbon incorporated into the porous metal structure is the loading amount of the above-mentioned positive electrode. The substantially uniform distribution of the carbon can further improve the performance of the rechargeable battery cell.

[0039] Whether the carbon is substantially uniformly distributed throughout the electrode or only in portions of it can be determined by cutting the electrode and examining different portions of it, such as by SEM.

[0040] In this disclosure, unless otherwise indicated, the term "substantially" is intended to encompass both all and most, but not all. For example, "substantially uniformly distributed" is intended to encompass both completely uniformly distributed and mostly, but not completely, uniformly distributed. Similarly, "substantially uniformly incorporated" is intended to encompass completely uniformly incorporated carbon and mostly, but not completely, incorporated carbon into pores.

[0041] As mentioned above, the carbon used to make the positive electrode can also be porous, thereby providing a large specific surface area. The specific surface area of the carbon used to make the positive electrode can be at least 200 m 2 / g, at least 600m 2 / g, at least 1000m 2 / g, at least 1400m 2 / g, at least 1600m 2 / g, and at least 2000m 2 / g, where higher capacity is required, higher surface area is generally preferred.

[0042] As discussed herein, the increase in surface area provided by carbon generally results in an increase in the capacity of the SO2 depolarizer cell and thus improves the performance data of the rechargeable battery cell. An example of a porous carbon material is soot. These soots include combustion soot (so-called "carbon black"), cracking soot (so-called "thermal black") in the form of lamp black, channel black and furnace black. Other examples of porous carbon materials are activated carbon, mesocarbon microbeads (MCMB), carbon nanotubes (CNT), multi-walled carbon nanotubes (MWCNT) and graphene. Natural graphite, artificial graphite (electrical graphite), graphite foil, coke (gas coke, metallurgical coke, petroleum coke, distilled coke), carbon fiber materials (glassy carbon, foamed carbon), coke, thermal graphite, aviation graphite, expanded graphite, fullerenes or amorphous carbon (graphitizable carbon and non-graphitizable carbon) can also be used as porous carbon materials. Other types of porous carbon may also be suitable for use.

[0043] In the case of using carbon, the carbon loading in the positive electrode can be at least 2 mg / cm 2 Up to 200mg / cm 2 In general, for a particular SO2 depolarizer cell, up to a point that can be determined experimentally, higher loads will increase the capacity of the SO2 depolarizer cell. However, beyond that point, higher loads may begin to be detrimental to the capacity and / or other desired performance characteristics of the SO2 depolarizer cell. In a SO2 depolarizer cell, a load of at least 2 mg / cm2 may be used. 2 , at least 5mg / cm 2 , at least 10mg / cm 2 , at least 15mg / cm 2 , at least 20mg / cm 2 , at least 30mg / cm 2 , at least 50mg / cm 2 of carbon, or at least 75 mg / cm 2 of carbon, or at least 100 mg / cm 2 The maximum loading of the positive electrode should preferably not exceed 200 mg / cm 2 More preferably, no more than 150 mg / cm 2 , most preferably not more than 100mg / cm 2 .

[0044] The weight of carbon in the positive electrode can be at least 20 wt%, at least 40 wt%, at least 60 wt%, at least 80 wt%, at least 90 wt% and at least 95 wt% relative to the total weight of materials distributed in the porous metal structure of the positive electrode.

[0045] As described above, materials other than carbon may be included in the positive electrode. For example, in an embodiment, the SO2 depolarizer cell may contain one or more metals or metal-containing compounds, such as oxides, which may catalyze a reaction resulting in one or more discharge products from the SO2 electrolyte during discharge and / or the reformation of SO2 during charging. In an embodiment, such chemical elements may include one or more metals selected from vanadium, nickel, copper, magnesium, manganese, titanium, aluminum, lead, palladium, tungsten, chromium, and combinations thereof. For example, the electrode may contain vanadium oxide. The additional chemical element (or compound containing the chemical element) may be present in the positive electrode at a concentration of 0.01 to 20 weight percent (wt %) or more, based on the total weight of the carbon in the electrode. For example, the concentration is 1 to 20 wt %, or 5 to 15 wt %, based on the total weight of the carbon in the electrode.

[0046] In general, electrodes with high porosity will provide higher capacity SO2-depolarized cells. Porosity refers to the ratio of the volume of the void space, where the void space is formed by pores, to the total volume of the positive electrode. Porosity results in an increase in the internal surface area of the positive electrode. Generally speaking, it is advantageous that the individual pores of the positive electrode can be completely filled with the SO2-based electrolyte during operation of the rechargeable battery cell. High porosity and, therefore, a large internal surface area are generally advantageous in order to absorb the solid reaction products formed by the SO2-based electrolyte during discharge. Porosity will be determined by many factors, including the porosity of the porous base electrode material (e.g., metal mesh), the loading of materials (e.g., binder and carbon) in the electrode (filling the pores in the porous base material), and any calendering performed to compress the electrode to reduce the overall volume of the electrode (discussed below). Reducing the electrode size by calendering (i.e., compressing the electrode) will reduce the electrode volume and, therefore, the porosity. Calendering can achieve a smaller battery size and / or the use of more electrodes, and can also increase mechanical stability.

[0047] Thus, in general, the porosity of a porous starting electrode material (e.g., metal foam) can be very high (e.g., greater than 90%), but the final porosity of the electrode will be lower. Depending on these factors, the porosity can therefore range from significantly less than 50% to greater than 97%, with the porosity preferably being at least 50%, more preferably at least 60%, more preferably at least 70%, more preferably at least 80%, more preferably at least 90%, more preferably at least 95%, and most preferably at least 97%. Starting electrode materials with higher porosity (e.g., metal foam) generally enable the construction of electrodes with greater loads and, therefore, higher energy capacities. Furthermore, porosity reduces the density of the electrodes, thereby reducing their weight, which can positively impact the overall weight of the rechargeable battery cell.

[0048] The porosity of the final positive electrode can be measured using a commercially available mercury porosimetry apparatus.The porosity of the starting electrode material (eg, metal foam) is typically available from the supplier.

[0049] In order to improve its mechanical strength and, for example, to bond carbon to a conductive element, the positive electrode generally includes at least one binder. This binder can be used with any or all of the SO2 depolarizer battery elements disclosed herein. The binder can be a fluorinated binder, particularly a terpolymer of polyvinylidene fluoride (PVDF) and / or tetrafluoroethylene, hexafluoropropylene and vinylidene fluoride (THV). In addition, the binder can include a polymer comprising a monomer structural unit of a conjugated carboxylic acid or an alkali metal salt, an alkaline earth metal salt or an ammonium salt of the conjugated carboxylic acid or a combination thereof. The binder can also include a polymer based on a monomer styrene structural unit or a butadiene structural unit. The binder can also belong to carboxyalkyl cellulose and its salts. At least one (or combination) of the above-mentioned binders may be present in the positive electrode. The amount of the binder used will be determined for each battery. Typically, the weight of the binder in the electrode will not exceed 30% relative to the total weight of the electrode, such as no more than 25% by weight, no more than 20% by weight, no more than 15% by weight, no more than 10% by weight, no more than 7% by weight, no more than 5% by weight, or no more than 2% by weight relative to the total weight of the electrode, such as 0.5 to 2.0%, 1-5%, 2.5-5%, 2-8%, 4-8%, 5-10%, 5-7.5%, 7.5%, 7.5-10%, 10-20%, 10-12.5%, 12.5-15%, 10-15%, 15-20%, 20-25%, 25-30%, with lower weight percentages generally preferred. The addition of the binder improves the long-term stability and service life of the rechargeable battery cell and can also serve to attach carbon to the metal electrode.

[0050] In addition to carbon, the positive electrode may optionally also contain metal halides, such as metal chlorides, metal fluorides and metal bromides. As a metal chloride, the positive electrode may contain, for example, copper chloride (CuCl2). These metal halides are electrochemically active materials that can be reduced during discharge of the rechargeable battery cell and oxidized during charging. The content of metal halide in the positive electrode may be at least 2 wt%, at least 5 wt%, at least 10 wt%, at least 20 wt%, at least 30 wt%, at least 40 wt%, at least 50 wt%, at least 60 wt%, at least 70 wt% and at least 80 wt% relative to the total weight of the electrode, with higher contents generally providing greater charge capacity. Therefore, the capacity characteristics of the positive electrode can be improved by adding metal halides, in particular metal chlorides.

[0051] The cathode of the SO2 depolarizer cell can be prepared as described below. A paste can be produced that includes carbon (advantageously porous) and a binder (e.g., a fluorinated binder). The fluorinated binder can first be dissolved in a solvent. The carbon and additional raw materials (e.g., catalyst) and / or solvent can then be added to the binder-solvent solution under stirring. The resulting composition is then introduced into a cathode support, such as a porous metal foam conductive element, so that the carbon is substantially evenly distributed throughout the cathode or a portion of the cathode. The cathode material is then dried or annealed at an elevated temperature to produce a cathode material. If desired, the cathode material can then be compressed to form a denser foam material. The following examples provide a description of the process for making the positive electrode of the SO2 depolarizer cell for use in the present disclosure.

[0052] negative electrode

[0053] Provided below are features and details of negative electrodes that can be used with the SO2 depolarizer cells of the present disclosure. While exemplary materials, dimensions, and other parameters are provided below to guide one of ordinary skill in formulating the negative electrode, the final formulation, materials, dimensions, quantity, location, and other parameters of the negative electrode will be determined based on the specific battery parameters and desired performance characteristics.

[0054] The negative electrode contains the active metal in the SO2 depolarizer cell. The active metal in a rechargeable battery cell is the metal whose ions in the electrolyte migrate to the negative or positive electrode during charging or discharging, where they participate in electrochemical processes that directly or indirectly result in the release of electrons to or absorption of electrons from an external circuit. Such active metals are alkali metals, alkaline earth metals, metals from Group 12 of the periodic table, or aluminum. When the rechargeable battery cell is charged, the active metal is stored in the negative electrode.

[0055] In practice, essentially all negative electrodes will employ an active metal selected from lithium, sodium, calcium, zinc, or aluminum. Among these, alkali metals, particularly lithium, are the most commonly used active materials in negative electrodes. The active metal is typically provided in the form of a metallic component, an alloy containing the active metal, an intermetallic compound containing the active metal, a carbon material containing the active metal, an inorganic material containing the active metal, or the like. The inorganic material may also comprise at least one oxide, at least one sulfide, at least one phosphide, at least one nitride, and / or at least one fluoride. The active metal content in the negative electrode may range from 20 to 100% by weight.

[0056] When lithium is used as the active metal, it is generally provided in the form of metallic lithium, lithium-containing alloys, lithium-containing intermetallic compounds, lithium-containing carbon materials, lithium-containing inorganic materials, and the like.

[0057] For example, if the conductive salt in the SO2-based electrolyte is an alkali metal salt in the form of a lithium salt, such as lithium tetrachloroaluminate (LiAlCl4), then the negative electrode can be composed of metallic lithium, lithium-containing carbon materials, lithium-containing alloys, oxides or sulfides of the following elements: tin, silicon, aluminum, phosphorus, zinc, gallium, germanium, silver, indium, antimony or bismuth.

[0058] If sodium is used as the active metal, metallic sodium, sodium-containing alloys, sodium-containing intermetallic compounds, sodium-containing carbon materials, sodium-containing inorganic materials, etc. can be used as the negative electrode material.

[0059] The amount of active material constituting the negative electrode (ie, the loading of the electrode relative to the surface area of the electrode) is selected from the group consisting of: at least 10 mg / cm 2 , at least 20mg / cm 2 , at least 40mg / cm 2 , at least 60mg / cm 2 , at least 80mg / cm 2 and at least 100 mg / cm 2 Generally speaking, a higher content of active material in the negative electrode has a positive impact on the charging and discharging processes of a rechargeable battery cell.

[0060] The negative electrode may have a thickness in the range of 0.05 mm to 20 mm, although the thickness will typically not exceed 15 mm. Thicknesses within this range are at least 0.05 mm, at least 0.10 mm, at least 0.50 mm, at least 1.00 mm, at least 1.50 mm, at least 2.00 mm, and at least 2.50 mm. The SO2 depolarizer cell may have multiple negative electrodes of the same thickness or of different thicknesses.

[0061] The negative electrode includes a conductive element. This negative electrode conductive element can have a planar structure or a three-dimensional porous metal structure, such as metal foam, fleece-like fabric, lattice, matrix, or grid. The negative electrode conductive element also serves to ensure the necessary electronic conductive connection of the negative electrode active material, thereby contributing to the performance of the SO2 depolarizer cell.

[0062] The negative electrode may also include at least one binder, which may contribute to the mechanical strength of the negative electrode. The binder may be a fluorinated binder, particularly a terpolymer of polyvinylidene fluoride (PVDF) and / or tetrafluoroethylene, hexafluoropropylene and vinylidene fluoride (THV). In addition, the binder may include a polymer consisting of monomer structural units of a conjugated carboxylic acid or an alkali metal salt, an alkaline earth metal salt or an ammonium salt of the conjugated carboxylic acid or a combination thereof. The binder may also include a polymer based on a monomer styrene structural unit or a butadiene structural unit. The binder may also belong to carboxyalkyl cellulose and its salts. Relative to the total weight of the electrode, the binder, such as those mentioned above, may be present in the negative electrode in an amount of no more than 20 wt %, no more than 15 wt %, no more than 10 wt %, no more than 7 wt %, and no more than 5 wt %, and no more than 2 wt %, with lower weight percentages generally preferred. Adding a binder may improve the long-term stability and service life of the rechargeable battery.

[0063] SO2-based electrolytes

[0064] As described above, the SO2 depolarizer cell includes an SO2-based electrolyte containing a concentration of SO2 sufficient to allow ion movement in a conductive salt that is contained in the electrolyte and causes charge transport. The SO2-based electrolyte also acts as an active electrode depolarizer.

[0065] The amount of SO2 in the SO2 depolarizer cell is typically at least 0.5 mol SO2 / mol conductive salt and typically no more than 20 mol SO2, preferably at least 1.0 mol SO2 and no more than 6.0 mol SO2, more preferably at least 2.0 mol SO2 and no more than 5.0 mol SO2 per mole (mol) of conductive salt. SO2-based electrolytes within this ratio between SO2 and conductive salt can generally dissolve more conductive salt than electrolytes based on organic solvent mixtures. Other values of SO2 concentration can also be used within the scope of the present invention. As shown in Experiment 7 and Table 3 below, when LiAlCl4 is used as the electrolyte, 1.0-3.0 mol SO2 / mol conductive salt and 1.5 mol SO2 / mol conductive salt can be used.

[0066] The concentration of SO2 in the electrolyte affects its vapor pressure. In the SO2 depolarizer cell disclosed herein, the SO2 depolarizer cell comprising a lower concentration of "SO2 / mol conductive salt" may not need to be under pressure and, therefore, may not require a pressurized housing. This can provide an advantageous battery in terms of the required manufacturing process compared to rechargeable lithium batteries that require a pressurized housing.

[0067] The SO2 concentration in the electrolyte also affects its conductivity. Depending on the SO2 concentration, different conductivity values can be achieved. Thus, by varying the SO2 concentration, the conductivity of the electrolyte can be adapted to the intended use of the SO2 depolarizer cell. SO2-based electrolytes typically contain 20 to 75% by weight of SO2, based on the total amount of electrolyte contained in the rechargeable cell, although values of 25% by weight of SO2, 30% by weight of SO2, and 40% by weight of SO2 are more preferred. The electrolyte can also contain up to 75% by weight of SO2, with a maximum of 65% by weight of SO2 and 55% by weight of SO2 being preferred in that order.

[0068] Typically, the SO2-based electrolyte comprises one or more conductive salts selected from the group consisting of alkali or alkaline earth metal aluminates, halides, oxalates, borates, phosphates, arsenates, and gallates. The conductive salt is typically a lithium tetrahaloaluminate, most typically LiAlCl4. The conductive salt in the SO2-based electrolyte may comprise at least 20 wt% of the electrolyte weight, at least 30 wt% of the electrolyte weight, at least 35 wt% of the electrolyte weight, at least 40 wt% of the electrolyte weight, at least 45 wt% of the electrolyte weight, or at least 50 wt% of the electrolyte weight.

[0069] In addition to the conductive salt, the SO2-based electrolyte may also typically contain an alkali or alkaline earth metal halide or a halide of an element from Group 11, 12, or 13 of the Periodic Table as an additive. It is desirable that, in addition to such halides, the other salts are present in an amount up to about 20% by weight of the total weight of the electrolyte, for example, at least 2% by weight, preferably at least 4% by weight, at least 6% by weight, more preferably at least 8% by weight, more preferably at least 10% by weight, and most preferably at least 12% by weight, based on the total weight of the electrolyte contained in the rechargeable battery cell. For example, the electrolyte may contain LiAlCl4 as a conductive salt and additional free aluminum chloride (AlCl3) as an additive. The addition of additives such as AlCl3 increases the capacity that can be recovered by the rechargeable battery cell. For example, such additives may interact or react with the SO2-based electrolyte, dissociate in the SO2-based electrolyte, participate in electrode processes, or may be present in the SO2-based electrolyte substantially chemically unchanged.

[0070] The amount of SO2 and conductive salt in the electrolyte may comprise preferably at least 50 wt% of the electrolyte weight, more preferably greater than 60 wt% of the electrolyte weight, more preferably greater than 70 wt% of the electrolyte weight, more preferably greater than 80 wt% of the electrolyte weight, more preferably greater than 85 wt% of the electrolyte weight, more preferably greater than 90 wt% of the electrolyte weight, more preferably greater than 95 wt% of the electrolyte weight or most preferably greater than 99 wt% of the electrolyte weight.

[0071] If desired, the SO2-based electrolyte may have only a limited amount of, or even no, additives containing organic matter and / or materials other than organic matter. Typically, the proportion of organic matter or other materials, such as flammable and / or explosive materials, in the SO2-based electrolyte, for example in the form of one or more solvents or additives, will be in the range of 0 to no more than 50% by weight, based on the weight of the electrolyte, such as no more than 40% by weight of the electrolyte, no more than 30% by weight of the electrolyte, no more than 20% by weight of the electrolyte, no more than 15% by weight of the electrolyte, no more than 10% by weight of the electrolyte, no more than 5% by weight of the electrolyte, no more than 1% by weight of the electrolyte, and substantially 0% by weight of the electrolyte. That is, the SO2-based electrolyte may be substantially free of organic solvents and / or other flammable and / or explosive materials. By keeping the content of organic solvents and other organic matter or other flammable or explosive materials in the SO2-based electrolyte at a low or even zero level, the electrolyte is rendered virtually non-flammable or substantially non-flammable, which in turn improves the operational safety of such SO2 depolarizer cells. As used herein, the term "flammable" refers to a material that is capable of igniting and burning readily. Compared to rechargeable batteries that contain flammable components, SO2 depolarizer cells are low in or essentially free of flammable components, thereby providing safety advantages.

[0072] Advantageously, SO2 based electrolyte is also substantially free of impurities, and impurities include water, organic matter and / or other materials. For example, such impurities may be caused by the carbonaceous coating of the positive electrode active material or by other carbonaceous materials (such as negative electrode). In an embodiment, water and organic impurities and / or other impurities are each present with an amount of less than 1000ppm, less than 500ppm, less than 400ppm, less than 300ppm, less than 200ppm, less than 100ppm, less than 50ppm, less than 25ppm, less than 10ppm, less than 5ppm, less than 1ppm and 0ppm. Advantageously, the amount of water and organic impurities is each limited to less than about 50ppm or less. Preferably, the electrolyte is substantially free of water. Preferably, the electrolyte is also substantially free of organic impurities.

[0073] partition

[0074] Rechargeable battery cells typically have a separator for electrically separating the positive and negative electrodes. The separator can be composed of a nonwoven material, a membrane, a woven or knitted fabric, an organic material, an inorganic material, or a combination thereof. Organic separators can be composed of unsubstituted polyolefins (e.g., polypropylene or polyethylene), polyolefins partially to completely substituted with halogens (e.g., partially to completely substituted with fluorine; e.g., PVDF, ETFE, PTFE), polyesters, polyamides, or polysulfones. Separators combining organic and inorganic materials include, for example, fiberglass textiles whose glass fibers are coated with a suitable polymer. The coating preferably includes a fluoropolymer such as polytetrafluoroethylene (PTFE), ethylene-tetrafluoroethylene (ETFE), perfluoroethylenepropylene (FEP), THV (a terpolymer of tetrafluoroethylene, hexafluoropropylene, and vinylidene fluoride), or a perfluoroalkoxy polymer (PFA). It may also include aminosilanes, polypropylene (PP), or polyethylene (PE). The separator can be further treated with a surfactant to improve wettability or other properties.

[0075] By combining the above-described positive electrode with an SO2-based electrolyte, an SO2-depolarizer battery cell can be produced that has one or more of the following properties and / or advantages:

[0076] - The theoretical calculated energy density of a SO2 depolarizer cell with a housing is about 1200Wh / kg relative to the total weight of the cell. At least 80% of the energy density can actually be used.

[0077] Depending on the carbon loading of the positive electrode, a discharge capacity of up to approximately 8000 mAh / carbon can be achieved. This discharge capacity is significantly higher than that of rechargeable battery cells containing lithium iron phosphate as the active material in the positive electrode. The discharge capacity is related to the carbon loading of the positive electrode.

[0078] -The positive electrode can be very thick, so fewer electrodes may be needed within the battery. This can simplify the current discharge and battery structure.

[0079] - Self-discharge is extremely low. For example, a fully charged battery loses less than 5%, less than 4%, less than 3%, less than 2%, or less than 1% of its capacity when stored at room temperature (i.e., 23°C) for one month. Therefore, the SO2 depolarizer battery cell can be stored for a long time after charging and can be used immediately without recharging.

[0080] - The energy content of rechargeable battery cells can be very high. This allows more energy to be delivered with fewer batteries, which can also lead to lower production costs.

[0081] If the positive electrode is made of carbon, production costs can be reduced compared to electrodes made of more expensive materials (e.g., alkali metal oxides or phosphates).

[0082] Due to the porosity of the positive electrode, SO2 depolarizer cells can have a lower overall weight compared to rechargeable cells without a porous positive electrode.

[0083] Thus, the rechargeable batteries disclosed herein may be suitable for a wide range of potential uses and applications, including but not limited to:

[0084] - power supplies for automobiles and recreational vehicles, such as those used in electric and hybrid vehicles, or to provide power to such vehicles, such as as batteries to start motors or operate equipment;

[0085] - Large transport vehicles such as trucks, locomotives, and ships;

[0086] - Smaller transportation devices such as golf carts, motorcycles, bicycles, scooters, ATVs, Segways, and similar self-propelled devices;

[0087] -Battery-operated toys and games;

[0088] - Emergency backup power or uninterruptible power supply (UPS) grid storage (e.g., for storing electricity during peak periods when demand is low), distributed generation, and independent power systems;

[0089] - Solar and wind energy storage;

[0090] - marine equipment, such as boats and marine engines or equipment intended to operate on board boats;

[0091] - Personal and small electronic devices such as laptops, tablets, mobile phones;

[0092] -Gaming equipment and accessories, such as remote controls and 3D headsets;

[0093] - Power supply for monitoring or alarm systems;

[0094] - Personal mobility devices such as electric wheelchairs and stair lifts,

[0095] - industrial machinery such as forklifts,

[0096] -Robots and robotic equipment, such as vacuum cleaners,

[0097] - Lawn and garden equipment, such as mowers, trimmers and chainsaws,

[0098] - Construction equipment such as power tools;

[0099] - agricultural equipment, such as tractors;

[0100] - aircraft, including airplanes, helicopters and drones;

[0101] - household appliances;

[0102] - portable power packs for providing power (including charging other rechargeable batteries); and

[0103] -Most applications currently using internal combustion engines.

[0104] A wide range of battery types can be produced, including those commonly used in household devices, such as AAA, AA, C, D, 9V, 18650, 21700 and 26650 sizes.

[0105] Other advantageous features of the present disclosure are described and explained in more detail below using drawings, examples, and experiments. BRIEF DESCRIPTION OF THE DRAWINGS

[0106] Figure 1 : shows a cross-sectional representation of one embodiment of an SO2 depolarizer cell as disclosed herein;

[0107] Figure 2 : An electron microscope image showing the three-dimensional porous structure of the metal foam of the SO2 depolarizer cell conductive element as disclosed herein;

[0108] Figure 3 : shows the discharge capacity of the positive electrode as a function of the number of charge and discharge cycles in the first half-cell experiment according to Experiment 1;

[0109] Figure 4 : shows two discharge curves of the positive electrode in the second half-cell experiment according to Experiment 2;

[0110] Figure 5 : shows the discharge capacity as a function of the number of charge and discharge cycles for the positive electrode from Experiment 2 compared with the positive electrode with catalyst in the third half-cell experiment according to Experiment 3;

[0111] Figure 6 : shows the discharge curves of positive electrodes of different thicknesses and charges in the fourth half-cell experiment of Experiment 4; and also shows the discharge curve of the positive electrode in the fifth half-cell experiment of Experiment 5;

[0112] Figure 7 : shows the functional relationship between the discharge capacity and the specific surface area of the carbon used for the positive electrode in the sixth half-cell experiment based on Experiment 6; and

[0113] Figure 8 : Shows the discharge curves of electrolytes with different SO2 concentrations in the seventh half-cell experiment based on Experiment 7. DETAILED DESCRIPTION

[0114] Figure 1A cross-sectional view of an exemplary embodiment of an SO2 depolarizer cell according to the present disclosure is provided. The SO2 depolarizer cell is shown as a prismatic cell and has, among other things, a housing 1. The housing 1 encloses an electrode array 3, which includes three positive electrodes 4 and four negative electrodes 5. The positive electrodes 4 and negative electrodes 5 are alternately stacked in the electrode array 3. In this exemplary embodiment, the positive electrode of the rechargeable battery cell is shown as a foam containing porous carbon, such as activated carbon. The negative electrode 5 is made of a metal, such as metallic lithium.

[0115] The housing 1 can also accommodate more positive electrodes 4 and / or negative electrodes 5. Typically, the number of negative electrodes 5 is preferably one more than the number of positive electrodes 4. As a result, the front surface of the electrode stack consists of the electrode surface of the negative electrode 5. The electrodes 4, 5 are connected to corresponding contacts 9, 10 of the cell via electrode tabs 6, 7. The rechargeable cell is filled with an SO2-based electrolyte (not shown), which advantageously can at least almost completely penetrate all pores or cavities of the positive electrodes 4, 5. In the SO2 depolarizer cell shown in the figure, the electrolyte can contain, for example, 1 mol of LiAlCl4 in 1.5 mol of SO2.

[0116] exist Figure 1 In the embodiment, the electrodes 4 and 5 have a flat design, i.e. a layer with a small thickness relative to its area. The electrodes 4 and 5 can have a Figure 1 The electrodes 5 and 6 may have substantially the same thickness as shown, but they may also have different thicknesses. For example, the negative electrode 5 may be thinner than the positive electrode 4. Each positive electrode may have the same or different thicknesses. Similarly, each negative electrode may have the same or different thicknesses.

[0117] The electrodes 4, 5 are separated from one another by separators 11. In this embodiment, these separators 11 are made of a glass fiber textile material. The housing 1 of the depicted rechargeable battery cell is essentially cuboid in shape, i.e., it has six essentially rectangular faces at right angles to one another. The electrodes 4, 5 and the walls of the housing 1 shown in the cross-section extend perpendicular to the layers and are essentially straight and flat.

[0118] Alternatively, however, the SO2 depolarizer cell can also be designed as a spiral-wound cell. In this spiral-wound cell design, the electrodes consist of thin layers that are intertwined with a separator material. The separator material spatially and electrically separates the positive and negative electrodes, but it is also permeable to the active metal ions. This creates a large electrochemically active surface area, resulting in correspondingly high current efficiency.

[0119] Rechargeable battery cells can also be designed as bobbin cells. In this case, a thick, porous positive electrode is located inside the battery casing and occupies the majority of the volume. Depending on whether the casing is circular or rectangular, one or more negative electrodes are used. These are placed between the casing wall and the thick positive electrode. The electrodes are electrically isolated from each other by a separator. The electrolyte is distributed in the cavities and pores within the casing.

[0120] Electrodes 4, 5 have conductive elements 41, 51 that allow the necessary electron conduction connection of the active material of each electrode 4, 5. Conductive elements 41, 51 are in contact with the active material participating in the electrode reaction of the respective electrode 4, 5. As mentioned above, porous metal foam is used for conductive element 41 of positive electrode 4. This metal foam extends substantially throughout the entire thickness of electrode 4. Carbon material is incorporated into the pores of this metal foam.

[0121] During the manufacture of the positive electrode 4, the carbon material can be incorporated into the porous structure of the conductive element 41 in such a way that the carbon material fills its pores substantially uniformly over the entire thickness of the metal structure. The electrode material produced in this way is then compacted under high pressure, for example by calendering.

[0122] Figure 2 : An electron microscope image showing a three-dimensional porous structure of a metal foam 13, which can be used to form a Figure 1 The conductive element of the positive electrode is shown. In this figure, the conductive element of the positive electrode is not filled with metal foam. The scale shows that the average diameter of the pores P is greater than 100 μm, that is, they are relatively large.

[0123] As discussed herein, such porous metal foams can extend to more than 90% of the total thickness "d" of the conductive element, e.g. Figure 1 As shown. The carbon can be distributed throughout the porous metal foam 13. Advantageously, the carbon is substantially uniformly distributed, thereby minimizing any changes in battery function due to variations in carbon distribution. To improve mechanical strength, the positive electrode 4 may also contain a binder such as THV.

[0124] Example 1: Preparation of positive electrode

[0125] The ratio of carbon to binder is about 75-96 wt% carbon in the form of "high surface carbon" and about 4-25 wt% binder. The ratio can be 92-96 wt% carbon in the form of "high surface carbon" and about 4-6 wt% binder.

[0126] The positive electrode was prepared as follows:

[0127] A paste is produced using 80 wt% of carbon with a high surface area and 20 wt% of a fluorinated binder. To this end, the fluorinated binder is first dissolved in a solvent. Thereafter, the carbon is added alternately with other solvents while stirring. The paste is then introduced substantially uniformly into the three-dimensional porous metal structure of the metal foam conductive element with an initial porosity of greater than 90%. This is then dried or annealed at 50°C for 1 hour, thereby producing the electrode material. After cooling, this electrode material (i.e., the carbon is uniformly introduced into the metal foam) is compressed by a calender from an initial thickness of 1.6 mm to a thickness of 0.5 mm. From this pressed and tempered electrode material, a surface of 1 cm is punched out. 2 The carbon loading of the positive electrode is about 3 mg / cm 2 .

[0128] In the following experiments, the positive electrode served as the electrode under test, the so-called working electrode. It was measured in a three-electrode half-cell. Both the reference and counter electrodes were made of metallic lithium. The SO₂-based electrolyte used in the half-cell had a composition of LiAlCl₄*1.5SO₂.

[0129] Eight experiments were performed using half-cells prepared using the method described in Example 1 or variations thereof.

[0130] Experiment 1

[0131] In a first experiment, the capacity of a half-cell was determined as a function of the number of charge and discharge cycles using a cathode prepared according to the method described in Example 1. The half-cell was based on a Figure 1 The three-electrode array described was immersed in an SO2-based electrolyte of the above composition. Figure 3 The capacity of the half-cell is shown as a function of the number of cycles. The number of cycles represents the number of times the charge and discharge operations are repeated. The half-cell is first formed using a charge / discharge rate of C / 10. These formation cycles are not shown. The term "formation cycle" refers to the initial cycling of the half-cell before the actual measurement begins. After these formation cycles, the half-cell is first discharged for 20 cycles at a discharge rate of C / 5 and then for another 20 cycles at a discharge rate of C / 2. By definition, the nominal capacity of the battery is discharged in 1 hour at a discharge rate of 1C, from which the discharge current can be determined accordingly. Figure 3 The capacities shown are adjusted for the amount of carbon (expressed in grams) contained in each positive electrode.

[0132] Figure 3 The discharge capacity of the half-cell after 40 cycles is shown to be approximately 4000 mAh / g carbon. Increasing the discharge rate from C / 5 to C / 2 does not affect the capacity output. This demonstrates the high capacity provided by the SO2 depolarizer battery of the present disclosure.

[0133] Experiment 2

[0134] In the second half-cell experiment, the positive electrode prepared based on Example 1 was discharged at a discharge rate of C / 5 and a discharge rate of C / 10, starting from a voltage of 3.85 volts to a final discharge voltage of 2.5 volts. Figure 4 The discharge curve of the half-cell is shown as a function of voltage in volts (V). At a discharge rate of C / 5, the capacity reaches approximately 4000 mAh / g carbon. This corresponds to the value of Example 1 above. However, at a lower discharge rate of C / 10, the capacity reaches approximately 6500 mAh / g carbon. This experiment demonstrates the high power capability of the SO2 depolarizer cell as disclosed herein.

[0135] Experiment 3

[0136] In the third half-cell experiment, the effect of the catalyst on capacity yield was tested. To this end, a catalyst was added to the positive electrode. Vanadium oxide (V2O5) served as the catalyst. The preparation method for the positive electrode using V2O5 as the catalyst was the same as in Example 1, except that the following composition was used as the electrode material:

[0137] 75 wt% carbon in the form of high surface carbon;

[0138] 20wt% fluorinated binder;

[0139] 5wt%V2O5.

[0140] This cathode was also used in the same half-cell experiment as described in Experiment 1. Figure 5 The capacity of the positive electrode without catalyst and the positive electrode with catalyst in Example 1 is shown as a function of the number of charge and discharge cycles. Figure 5 The results show that if V2O5 is used as a catalyst in the cathode, better capacity efficiency can be achieved. On average, the cathode with the catalyst achieved a higher capacity of 300mAh-400mAh / g carbon.

[0141] Experiment 4

[0142] In the fourth half-cell experiment, the effect of the thickness of the positive electrode and its carbon loading per square centimeter of electrode surface on the capacity was tested. Table 1 shows the thickness and loading of the positive electrode used in half-cell experiment 4 and the capacity obtained in half-cell experiment 4.

[0143] Positive electrode 1 was prepared as described in Example 1. For positive electrodes 2 and 3, thicker metal foam and 18 wt% fluorinated binder and 2 wt% carboxyalkyl cellulose-based binder were used. These positive electrodes 1, 2, and 3 were discharged at a discharge rate of C / 5, starting from a voltage of 3.85 V to a final discharge voltage of 2.5 V. For ease of comparison, the capacity was normalized to an electrode surface area of 1 cm 2 . Figure 6 The results for different positive electrodes 1, 2 and 3 are shown. In addition, Table 1 lists the values of mAh / cm 2 The capacity reached by the unit.

[0144] Table 1: Characteristics of the cathodes used

[0145] positive electrode Thickness [mm] <![CDATA[Load [mg / cm 2 > <![CDATA[Capacity [mAh / cm 2 > 1 0.5 3 11.5 2 1.7 9 23.4 3 2.0 12 28.2

[0146] The thin cathode 1 with low loading showed 11.5 mAh / cm 2 By increasing the thickness and loading, as in the case of electrodes 2 and 3, significantly higher capacity values were obtained.

[0147] Experiment 5

[0148] In the fifth half-cell experiment, the effect of positive electrode porosity on capacity was studied. Table 2 shows the thickness and loading of the positive electrodes used in this half-cell experiment, as well as the obtained capacities. In Table 2, electrode 3 is the electrode 3 of experiment 4.

[0149] Table 2: Characteristics of the positive electrodes used

[0150] positive electrode Thickness [mm] <![CDATA[Load [mg / cm 2 > Capacity [mAh / g-carbon] 3 2.0 12 2348 4 4.0 12 3398

[0151] For positive electrodes 3 and 4, metal foams of different thicknesses were filled with the same amount of carbon per square centimeter. For the production of electrode 3, 18 wt% of a fluorinated binder and 2 wt% of a carboxyalkyl cellulose-based binder were used. Electrode 4 was made with 10 wt% of a carboxyalkyl cellulose-based binder. By using metal foams of different thicknesses at the same 12 mg / cm 2 The electrodes with different porosities were obtained by loading. The thicker electrode 4 showed a higher porosity compared to the thinner electrode 3. These positive electrodes 3 and 4 were discharged at a discharge rate of C / 5, starting from a voltage of 3.85 V until a final discharge voltage of 2.5 V, see Figure 6 .

[0152] Figure 6It was shown that increasing the thickness at constant load leads to a significant increase in capacity values. The use of metal foams or other highly porous conductive elements with a three-dimensional porous metal structure appears to be responsible for the increased capacity at constant load. On the one hand, this three-dimensional porous metal structure allows the production of thick positive electrodes with sufficient electronic contact with the external circuit. On the other hand, the high porosity achieved provides ample space for the active electrodes in these SO2 depolarizer cells to react and form discharge products.

[0153] Experiment 6

[0154] In order to investigate the influence of the specific surface area of the carbon used, two different positive electrodes were prepared as described in Example 1. In each case a carbon with a specific surface area of 800 m 2 / g or 1200m 2 / g of carbon. In half-cell experiments, the corresponding capacity of each positive electrode was determined based on the number of charge and discharge cycles (see Figure 7 ). A charge / discharge rate of C / 10 was used to form the half-cell. The formation cycles are not shown. The half-cell was first cycled 20 times at a C / 5 discharge rate and then another 20 cycles at a C / 2 discharge rate. Figure 7 As shown, the positive electrode with a larger specific surface area is 1200m 2 / g, its capacity is significantly higher than 800m 2 / g of positive electrode with a smaller specific surface area.

[0155] Experiment 7

[0156] In another half-cell experiment, the relationship between the achievable capacity and the SO₂ content used in the SO₂-based electrolyte was investigated. Five different LiAlCl₄*xSO₂-based electrolytes were prepared. The values of x were 1.0, 1.5, 2.0, 2.5, and 3.0. Table 3 summarizes the electrolytes used in Example 7 and the achieved capacities.

[0157] Table 3: Electrolytes used in Experiment 7

[0158] serial number electrolytes Capacity [mAh / g-carbon] 1 <![CDATA[LiAlCI4*1.0SO2]]> 3095 2 <![CDATA[LiAlCI4*1.5SO2]]> 4070 3 <![CDATA[LiAlCI4*2.0SO2]]> 4475 4 <![CDATA[LiAlCI4*2.5SO2]]> 3735 5 <![CDATA[LiAlCI4*3.0SO2]]> 1950

[0159] In half-cell experiments, the positive electrodes prepared according to Example 1 were discharged in the respective electrolytes at a discharge rate of C / 5, starting from a voltage of 3.85 V up to a final discharge voltage of 2.5 V. Figure 8 The obtained discharge curves are shown in Table 3. As mentioned above, the obtained capacities are summarized in Table 3. Figure 8As shown, the optimal concentration for the cell is 1.5 to 2.5 mol SO₂ per mol of conductive salt, or approximately 2.0 mol SO₂ per mol of conductive salt. At this SO₂ concentration, a capacity of almost 4500 mAh / g of carbon is achieved. Reducing the sulfur dioxide content from 2.0 to 1.5 mol SO₂ per mol of conductive salt, or increasing the sulfur dioxide content from 2.0 to 2.5 mol SO₂ per mol of conductive salt, results in lower capacity values.

[0160] Experiment 8

[0161] In the eighth half-cell experiment, the effects of additives added to SO2-based electrolytes were analyzed. AlCl3 was used as the additive. An electrolyte based on LiAlCl4*1.5SO2 was prepared. AlCl3 was added to three samples of this electrolyte at concentrations of 4 wt%, 8 wt%, and 12 wt%, based on the total weight of the electrolyte. In this half-cell experiment, the positive electrode prepared according to Example 1 was discharged in the respective electrolyte at a discharge rate of C / 10, starting from a voltage of 3.85 volts to a final discharge voltage of 2.5 volts. Two discharge cycles were performed. The capacities achieved for the respective electrolytes for discharge cycles 1 and 2 are listed in Table 4.

[0162] Table 4: Electrolytes used in Experiment 8

[0163]

[0164] As shown in Table 4, the higher the AlCl₃ concentration, the higher the achievable discharge capacity. In the first cycle, a capacity of approximately 34,000 mAh / g carbon was achieved at a 12 wt% AlCl₃ concentration. In this case, compared to Experiment 2 above, a capacity value almost seven times higher was achieved in the first cycle. Here, at a discharge rate of C / 10 and an electrolyte without additives, a capacity of 6,500 mAh / g carbon was achieved. Even in the second discharge cycle, it was possible to achieve a capacity twice as high.

[0165] definition

[0166] For convenience, certain terms used in the specification and appended claims are collected here. These definitions should be read in light of the entire disclosure and understood by those skilled in the art.

[0167] Unless expressly stated otherwise, the articles "a" and "an" as used herein in the specification and claims should be understood to mean "at least one."

[0168] As used herein in the specification and claims, the phrase "and / or" should be understood to mean "one or both" of the elements so combined, i.e., elements that are present in combination in some cases and separately in other cases. Multiple elements listed with "and / or" should be interpreted in the same manner, i.e., "one or more" of the elements so combined. In addition to the elements specifically identified by the "and / or" clause, other elements may optionally be present, whether related or unrelated to those specifically identified elements. Thus, as a non-limiting example, when used in conjunction with open language such as "comprising," a reference to "A and / or B" may, in one embodiment, refer to only A (optionally including elements in addition to B); in another embodiment, to only B (optionally including elements in addition to A); in another embodiment, to both A and B (optionally including other elements); etc.

[0169] As used herein in the specification and claims, the phrase "or" should be understood to mean "one or both" of the elements so combined, i.e., elements that are present in combination in some cases and separately in other cases. Multiple elements listed with "or" should be interpreted in the same manner, i.e., "one or more" elements are so combined. In addition to the elements specifically identified by the "or" clause, other elements may optionally be present, whether related or unrelated to those specifically identified elements. Thus, as a non-limiting example, when used in conjunction with open language such as "comprising," a reference to "A or B" may, in one embodiment, refer to only A (optionally including elements in addition to B); in another embodiment, to only B (optionally including elements in addition to A); in another embodiment, to both A and B (optionally including other elements); etc.

[0170] As used herein in the specification and claims, the phrase "at least one" with respect to a series of one or more elements should be understood to mean at least one element selected from any one or more elements in the series of elements, but does not necessarily include at least one of each element specifically listed in the series of elements, and does not exclude any combination of elements in the series of elements. This definition also allows that elements other than the elements specifically identified in the series of elements to which the phrase "at least one" refers may optionally be present, whether related or unrelated to those specifically identified elements. Thus, as a non-limiting example, "at least one of A and B" (or equivalently, "at least one of A or B," or equivalently, "at least one of A and / or B") may, in one embodiment, refer to at least one, optionally including more than one, A, with no B present (and optionally including elements other than B); in another embodiment, may refer to at least one, optionally including more than one, B, with no A present (and optionally including elements other than A); in another embodiment, may refer to at least one, optionally including more than one, A, and at least one, optionally including more than one, B (and optionally including other elements); etc.

[0171] It should also be understood that, unless expressly stated to the contrary, the processes described herein and claimed below may include steps in addition to those recited, and that the order of the steps or actions of a process is not necessarily limited to the order in which the steps or actions of the process are recited. In the context of this disclosure, the words "process" and "method" are synonymous.

[0172] In the claims and the specification, all transitional phrases such as "comprising," "consisting of," "including," "carrying," "having," "containing," "involving," "holding," and "consisting of" should be understood as open-ended, meaning including but not limited to. Only the transitional phrases "consisting of" and "consisting essentially of" are closed or semi-closed transitional phrases.

[0173] Those skilled in the art will recognize, or be able to ascertain using no more than routine experimentation, many equivalents to the specific embodiments described herein. Such equivalents are intended to be encompassed by the following claims.

Claims

1. A rechargeable battery cell comprising a housing (1), at least one positive electrode (4), at least one negative electrode (5) and a sulfur dioxide-based electrolyte as an active electrode depolarizer; characterized in that The positive electrode (4) is porous and comprises carbon, and The positive electrode has a thickness of at least 0.2 mm, and the positive electrode (4) includes a conductive element (41) having a three-dimensional porous metal structure, and the specific surface area of the carbon used to make the positive electrode is at least 200 m 2 / g, And wherein the porosity of the positive electrode is at least 50%.

2. The rechargeable battery cell according to claim 1, wherein The positive electrode (4) comprises carbon and at least one other chemical element or at least one compound comprising the chemical element in the form of a metal oxide; wherein the chemical element is selected from the group consisting of vanadium, nickel, copper, magnesium, manganese, titanium, aluminum, lead, palladium, tungsten and chromium; and, The other chemical element or the compound containing the chemical element is present in a concentration of 1 to 20% by weight relative to the total weight of the carbon of the electrode.

3. The rechargeable battery unit according to claim 1, wherein: The porous metal structure extends over at least 70% of the thickness of the positive electrode.

4. The rechargeable battery cell of claim 3, wherein the three-dimensional porous metal structure is in the form of a metal foam.

5. The rechargeable battery unit according to claim 3 or 4, characterized in that: The porous metal structure of the conductive element (41) includes carbon, and the carbon is substantially uniformly distributed within the porous metal structure.

6. The rechargeable battery unit according to claim 1, wherein: The carbon content of the positive electrode (4) is at least 2 mg / cm based on the surface area of the positive electrode. 2 .

7. The rechargeable battery unit according to claim 1, wherein: The positive electrode has a porosity of at least 60%.

8. The rechargeable battery unit according to claim 1, wherein: The positive electrode (4) comprises a binder, a fluorinated binder, or a binder comprising a polymer consisting of monomeric structural units of a conjugated carboxylic acid or an alkali metal, alkaline earth metal or ammonium salt of such a conjugated carboxylic acid or a combination thereof, or adhesives consisting of polymers based on the monomeric structural units of styrene and butadiene, or a binder selected from the group consisting of carboxymethyl cellulose, The binder is present in a maximum concentration of 20% by weight relative to the total weight of the electrode.

9. The rechargeable battery unit according to claim 1, wherein: The sulfur dioxide-based electrolyte comprises a conductive salt selected from the group consisting of aluminates, halides, oxalates, borates, phosphates, arsenates, and gallates of alkali metals or alkaline earth metals.

10. The rechargeable battery cell according to claim 1, wherein The sulfur dioxide-based electrolyte contains at least 0.5 mol SO2 and no more than 20 mol SO2 per mol of conductive salt.

11. The rechargeable battery unit according to claim 1, wherein: The sulfur dioxide-based electrolyte comprises an alkali metal halide or an alkaline earth metal halide or a halide of an element from Group 11, 12 or 13 of the Periodic Table of Elements.

12. The rechargeable battery unit according to claim 1, wherein: The negative electrode (5) contains an active metal, and the active metal is an alkali metal, an alkaline earth metal, a metal of Group 12 of the periodic table, or aluminum.

13. The rechargeable battery unit according to claim 12, wherein: The active metal of the negative electrode (5) is lithium, sodium, calcium, zinc or aluminum.

14. The rechargeable battery unit according to claim 1, wherein: The amount of active material of the negative electrode (5) is at least 10 mg / cm based on the surface area of the negative electrode. 2 .

15. The rechargeable battery cell according to claim 1, wherein The negative electrode (5) has a thickness of at least 0.05 mm.

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