Classifications

• • H—ELECTRICITY
  • H01—ELECTRIC ELEMENTS
  • H01M—PROCESSES OR MEANS, e.g. BATTERIES, FOR THE DIRECT CONVERSION OF CHEMICAL ENERGY INTO ELECTRICAL ENERGY
  • H01M4/00—Electrodes
  • H01M4/02—Electrodes composed of, or comprising, active material
  • H01M4/13—Electrodes for accumulators with non-aqueous electrolyte, e.g. for lithium-accumulators; Processes of manufacture thereof
  • H01M4/139—Processes of manufacture
• • H—ELECTRICITY
  • H01—ELECTRIC ELEMENTS
  • H01M—PROCESSES OR MEANS, e.g. BATTERIES, FOR THE DIRECT CONVERSION OF CHEMICAL ENERGY INTO ELECTRICAL ENERGY
  • H01M10/00—Secondary cells; Manufacture thereof
  • H01M10/05—Accumulators with non-aqueous electrolyte
  • H01M10/052—Li-accumulators
• • H—ELECTRICITY
  • H01—ELECTRIC ELEMENTS
  • H01M—PROCESSES OR MEANS, e.g. BATTERIES, FOR THE DIRECT CONVERSION OF CHEMICAL ENERGY INTO ELECTRICAL ENERGY
  • H01M10/00—Secondary cells; Manufacture thereof
  • H01M10/05—Accumulators with non-aqueous electrolyte
  • H01M10/056—Accumulators with non-aqueous electrolyte characterised by the materials used as electrolytes, e.g. mixed inorganic/organic electrolytes
  • H01M10/0561—Accumulators with non-aqueous electrolyte characterised by the materials used as electrolytes, e.g. mixed inorganic/organic electrolytes the electrolyte being constituted of inorganic materials only
  • H01M10/0563—Liquid materials, e.g. for Li-SOCl2 cells
• • H—ELECTRICITY
  • H01—ELECTRIC ELEMENTS
  • H01M—PROCESSES OR MEANS, e.g. BATTERIES, FOR THE DIRECT CONVERSION OF CHEMICAL ENERGY INTO ELECTRICAL ENERGY
  • H01M10/00—Secondary cells; Manufacture thereof
  • H01M10/42—Methods or arrangements for servicing or maintenance of secondary cells or secondary half-cells
  • H01M10/4235—Safety or regulating additives or arrangements in electrodes, separators or electrolyte
• • H—ELECTRICITY
  • H01—ELECTRIC ELEMENTS
  • H01M—PROCESSES OR MEANS, e.g. BATTERIES, FOR THE DIRECT CONVERSION OF CHEMICAL ENERGY INTO ELECTRICAL ENERGY
  • H01M4/00—Electrodes
  • H01M4/02—Electrodes composed of, or comprising, active material
  • H01M4/04—Processes of manufacture in general
  • H01M4/0438—Processes of manufacture in general by electrochemical processing
• • H—ELECTRICITY
  • H01—ELECTRIC ELEMENTS
  • H01M—PROCESSES OR MEANS, e.g. BATTERIES, FOR THE DIRECT CONVERSION OF CHEMICAL ENERGY INTO ELECTRICAL ENERGY
  • H01M4/00—Electrodes
  • H01M4/02—Electrodes composed of, or comprising, active material
  • H01M4/04—Processes of manufacture in general
  • H01M4/0438—Processes of manufacture in general by electrochemical processing
  • H01M4/044—Activating, forming or electrochemical attack of the supporting material
  • H01M4/0445—Forming after manufacture of the electrode, e.g. first charge, cycling
• • H—ELECTRICITY
  • H01—ELECTRIC ELEMENTS
  • H01M—PROCESSES OR MEANS, e.g. BATTERIES, FOR THE DIRECT CONVERSION OF CHEMICAL ENERGY INTO ELECTRICAL ENERGY
  • H01M4/00—Electrodes
  • H01M4/02—Electrodes composed of, or comprising, active material
  • H01M4/13—Electrodes for accumulators with non-aqueous electrolyte, e.g. for lithium-accumulators; Processes of manufacture thereof
• • H—ELECTRICITY
  • H01—ELECTRIC ELEMENTS
  • H01M—PROCESSES OR MEANS, e.g. BATTERIES, FOR THE DIRECT CONVERSION OF CHEMICAL ENERGY INTO ELECTRICAL ENERGY
  • H01M4/00—Electrodes
  • H01M4/02—Electrodes composed of, or comprising, active material
  • H01M4/13—Electrodes for accumulators with non-aqueous electrolyte, e.g. for lithium-accumulators; Processes of manufacture thereof
  • H01M4/134—Electrodes based on metals, Si or alloys
• • H—ELECTRICITY
  • H01—ELECTRIC ELEMENTS
  • H01M—PROCESSES OR MEANS, e.g. BATTERIES, FOR THE DIRECT CONVERSION OF CHEMICAL ENERGY INTO ELECTRICAL ENERGY
  • H01M4/00—Electrodes
  • H01M4/02—Electrodes composed of, or comprising, active material
  • H01M4/64—Carriers or collectors
  • H01M4/66—Selection of materials
  • H01M4/665—Composites
  • H01M4/667—Composites in the form of layers, e.g. coatings
• • H—ELECTRICITY
  • H01—ELECTRIC ELEMENTS
  • H01M—PROCESSES OR MEANS, e.g. BATTERIES, FOR THE DIRECT CONVERSION OF CHEMICAL ENERGY INTO ELECTRICAL ENERGY
  • H01M4/00—Electrodes
  • H01M4/02—Electrodes composed of, or comprising, active material
  • H01M4/64—Carriers or collectors
  • H01M4/70—Carriers or collectors characterised by shape or form
  • H01M4/80—Porous plates, e.g. sintered carriers
• • H—ELECTRICITY
  • H01—ELECTRIC ELEMENTS
  • H01M—PROCESSES OR MEANS, e.g. BATTERIES, FOR THE DIRECT CONVERSION OF CHEMICAL ENERGY INTO ELECTRICAL ENERGY
  • H01M4/00—Electrodes
  • H01M4/02—Electrodes composed of, or comprising, active material
  • H01M2004/021—Physical characteristics, e.g. porosity, surface area
• • H—ELECTRICITY
  • H01—ELECTRIC ELEMENTS
  • H01M—PROCESSES OR MEANS, e.g. BATTERIES, FOR THE DIRECT CONVERSION OF CHEMICAL ENERGY INTO ELECTRICAL ENERGY
  • H01M4/00—Electrodes
  • H01M4/02—Electrodes composed of, or comprising, active material
  • H01M2004/026—Electrodes composed of, or comprising, active material characterised by the polarity
  • H01M2004/027—Negative electrodes
• • H—ELECTRICITY
  • H01—ELECTRIC ELEMENTS
  • H01M—PROCESSES OR MEANS, e.g. BATTERIES, FOR THE DIRECT CONVERSION OF CHEMICAL ENERGY INTO ELECTRICAL ENERGY
  • H01M4/00—Electrodes
  • H01M4/02—Electrodes composed of, or comprising, active material
  • H01M4/13—Electrodes for accumulators with non-aqueous electrolyte, e.g. for lithium-accumulators; Processes of manufacture thereof
  • H01M4/131—Electrodes based on mixed oxides or hydroxides, or on mixtures of oxides or hydroxides, e.g. LiCoOx
• • Y—GENERAL TAGGING OF NEW TECHNOLOGICAL DEVELOPMENTS; GENERAL TAGGING OF CROSS-SECTIONAL TECHNOLOGIES SPANNING OVER SEVERAL SECTIONS OF THE IPC; TECHNICAL SUBJECTS COVERED BY FORMER USPC CROSS-REFERENCE ART COLLECTIONS [XRACs] AND DIGESTS
  • Y02—TECHNOLOGIES OR APPLICATIONS FOR MITIGATION OR ADAPTATION AGAINST CLIMATE CHANGE
  • Y02E—REDUCTION OF GREENHOUSE GAS [GHG] EMISSIONS, RELATED TO ENERGY GENERATION, TRANSMISSION OR DISTRIBUTION
  • Y02E60/00—Enabling technologies; Technologies with a potential or indirect contribution to GHG emissions mitigation
  • Y02E60/10—Energy storage using batteries

Definitions

• the invention relates to a, preferably non-aqueous, rechargeable electrochemical battery cell with a negative electrode, an electrolyte and a positive electrode, in which at least one of the electrodes has a (usually flat) electronically conductive substrate with a surface on which an active one when the cell is charged Mass is deposited electrolytically.
• alkali metal cells in which the active mass is an alkali metal which is deposited on the negative electrode when the cell is charged.
• the invention is particularly directed to a battery cell in which the active composition is a metal, in particular an alkali metal, alkaline earth metal or a metal of the second subgroup of the periodic table, lithium being particularly preferred.
• the electrolyte used in the context of the invention is preferably based on SO2.
• SO 2 based electrolyte SO 2 based electrolytes
• SO 2 based electrolytes SO 2 based electrolytes
• a tetrahaloaluminate of the alkali metal for example, is preferably used as the conductive salt
• LiAlCl4 used.
• An alkali metal cell with an SC> 2 based electrolyte is called an alkali metal SO 2 cell.
• the required safety is an important problem with battery cells. For many cell types, particularly strong heating can lead to safety-critical conditions. It may happen that the cell housing bursts or at least becomes leaky and harmful gaseous or solid substances or even fire escape. A rapid increase in temperature can be caused not only by improper handling, but also by internal or external short circuits when the cell is operating.
• Battery manufacturers use electronic, mechanical or chemical mechanisms to control the charging or discharging circuit in such a way that the current flow is interrupted below a critical temperature so that no "thermal runaway” can occur.
• pressure-sensitive mechanical or temperature-sensitive electronic switches are integrated in the internal battery circuit.
• chemical reactions in the electrolyte or mechanical Changes in the battery separator irreversibly interrupt the current transport within these components as soon as a critical temperature threshold is reached.
• Li-ion cells are only used with complex electronic monitoring because the security risks based on the current state of the art are very high.
• the invention is based on the problem of improving the function, in particular the safety, of electrochemical battery cells in a simple and inexpensive manner.
• a microporous structure is provided in direct contact with the electronically conductive substrate, the pore size of which is dimensioned such that the active mass deposited during the charging process is controlled in its way Pore grows into it.
• the pores are preferably completely filled by the active mass growing into the porous structure, so that the active Mass is only in contact with the electrolyte over the relatively small interfaces at which further deposition takes place.
• the overall reduction in the electrolyte volume contained in the cell has also proven to be advantageous.
• the invention is therefore particularly advantageous to use in connection with a battery cell according to international patent application WO 00/79631 AI, which can be operated with a very small amount of electrolyte.
• It is a cell whose negative electrode contains an active metal, in particular an alkali metal, in the charged state, whose electrolyte is based on sulfur dioxide and which has a positive electrode which contains the active metal and from which ions are charged into the electrolyte during the charging process escape.
• the electrolyte is based on sulfur dioxide.
• a self-discharge reaction takes place at the negative electrode, in which the sulfur dioxide of the electrolyte reacts with the active metal of the negative electrode to form a poorly soluble compound.
• the electrochemical charge quantity of the sulfur dioxide contained in the cell is smaller than the electrochemically theoretically in the positive Electrode storable amount of charge of the active metal.
• the battery cell can be operated with a significantly reduced amount of electrolyte and yet an improved function.
• the structure of a layer directly adjoining the substrate of the negative electrode is determined by the size and shape of the solid particles, which are also referred to below as "structure-forming particles".
• the porous structure can be formed both from particles that are not connected to one another and from a particle composite. If a binder is present in the porous structure for the production of a particle composite, the binder should not have an excessively high proportion of less than 50%, preferably less than 30%, of the total solid volume of the porous structure.
• the proportion of binder is preferably so low that the binder is located only in the region of the contact points between the structure-forming particles. For this reason, binder proportions (volume ratio of the binder to the total volume of the structure-forming particles) of less than 20% or even less than 10% are particularly preferred.
• this connection should have a certain elasticity.
• a particle composite produced by sintering is too rigid, because the mechanical stresses on the porous structure during operation of the cell can lead to fractures, which impair the safety properties of the battery cell.
• a porous structure made up of particles that are not connected to one another is advantageous in this regard because the forces and stresses occurring during the loading and unloading of the cell are absorbed more uniformly without breaking or gaps occurring.
• the structure-forming particles should be packed so tightly that they cannot be moved within the structure during operation of the cell.
• the volume filling level of the solid portion of the porous structure (percentage relation between the solid volume and the total volume of the porous structure) should be high , It should be at least 40%, preferably at least 50%, particularly preferably at least 55%. These values are higher than the volume filling level of conventional fillings of (usually crystalline) solid particles.
• the desired compact structure can be achieved with different methods:
• the density (and thus the degree of volume filling) of a loose bed can be increased by mechanical vibration (tapping, shaking or pounding) beyond the bulk density that is characteristic of the respective particles. According to the experimental testing of the invention, such methods can be economically integrated into the manufacturing process of the battery cells.
• the degree of volume filling depends to a large extent on the shape of the structure-forming particles.
• particles are used to form the porous structure, the shape of which largely approximates the spherical shape, so that their bulk density is higher than the bulk density of the same substance in crystalline form.
• An increased degree of volume filling can also be achieved in that the porous structure contains two fractions of structure-forming solid particles with defined different average particle sizes, the particle sizes of the fractions complementing one another in such a way that an increased volume filling degree results.
• the structure-forming particles of the finer fraction are preferably stored in the
• the structure-forming solid particles should preferably consist of a material which is inert to the electrolyte, its charge products and the active composition.
• a material which is inert to the electrolyte, its charge products and the active composition For example, ceramic powders are suitable, under certain circumstances also particles made of amorphous materials, in particular glasses, while ionically dissociating materials (salts) should not be used for the structure-forming component.
• the material of the structure-forming solid particles should have a sufficiently high melting point of at least 200 ° C., preferably at least 400 ° C.
• Compounds which do not contain oxygen are particularly suitable from a safety point of view.
• Silicon carbide is particularly suitable in view of its good availability and high thermal conductivity.
• connections are preferred which have a high thermal conductivity of at least 5 W / mK, preferably at least 20 W / mK.
• oxygen-containing compounds can also be advantageous. This applies in particular to Si0 2 , which is also available inexpensively in the form of spherical particles.
• FIG. 1 shows a cross-sectional illustration of a battery cell according to the invention
• Fig. 2 is a perspective view of the interior
• FIG. 3 shows a basic illustration of a porous structure between a conductor element (substrate) of a negative electrode and a separator
• FIG. 4 shows an enlarged detailed illustration of FIG. 3,
• Fig. 5 is a detailed representation of the principle of one of two fractions with different mean
• Fig. 6 shows a detailed representation of the principle of a porous
• the housing 1 of the battery 2 shown in FIG. 1 consists for example of stainless steel and encloses the electrode arrangement 3 shown in FIG. 2, which has a plurality of positive electrodes 4 and negative electrodes 5.
• the electrodes 4, 5 are - as is common in battery technology - connected to corresponding connection contacts 9, 10 of the battery via electrode connections 6, 7, the negative contact 10 being formed by the housing 1.
• the electrodes 4, 5 are flat in the usual way, i.e. as layers with a small thickness in relation to their surface area. They are separated from each other by separators 11.
• the positive electrodes are covered on both sides by two layers 11a, 11b of the separator material.
• the surface area of the two layers 11a, 11b is somewhat larger than the area of the positive electrodes, wherein they are connected to one another at their projecting edges, for example by means of a circumferential adhesive layer 13, which is only indicated schematically.
• the positive electrodes 4 are completely enclosed by the separators 11.
• the positive electrodes preferably consist of an intercalation compound of a metal oxide, in the case of a lithium cell, for example, of lithium cobalt oxide.
• the negative electrodes each have an electronically conductive substrate 14 as a conductor element, on which an active mass is electrolytically deposited when the cell is being charged.
• the substrate 14 is very thin in comparison to the positive electrode 4 and therefore only shown as a dark line.
• it preferably consists of a porous metal structure, for example wise in the form of a perforated plate, grid, metal foam or expanded metal.
• a porous structure 16 made of solid particles 17 which is more clearly recognizable in FIGS. 3 and 4 and which is so firm and compact that the solid particles are immovably fixed therein.
• the active mass 15 (only shown in FIG. 4), which is electrolytically deposited on the surface of the substrate 14, penetrates into its pores 18 and is evenly deposited therein, gradually displacing the electrolyte 19 from the pores 18.
• the contact area 20 between the electrolyte and the active mass is very small because it is limited to the narrow pores 18 of the porous structure 16.
• the porous structure 16 should be designed and arranged such that no accumulations of the active mass 15 can form in cavities that are substantially larger than the pores of the porous structure. Since the porous structure 16 does not form a bond with the substrate 14 or the separator 11 in the sense that the layers adhere to one another (without the action of external forces), such cavities can exist between the substrate 14 and the porous structure 16 as well also be present between the porous structure 16 and the separator 11 and within the porous structure 16 itself or arise during operation of the cell. In order to avoid this, the intermediate space 21 between the substrate 14 and the separator 11 should be completely filled in such a way that no voids remain which are substantially larger than the pores of the porous structure and in which there are accumulations of the active mass deposited during charging could form.
• the porous structure can be produced by filling the solid particles dry into the cell as a free-flowing powder.
• the solid particles can then be compressed by tapping, shaking or shaking in order to achieve the desired degree of volume filling.
• it is generally sufficient to fill the intermediate space 21 between the substrate 14 and the separator 11 in practice it is expedient if all of the cavities present in the cell are filled. Therefore, in the cell shown in FIG. 1, the porous structure 16 is also present in the space above the electrode arrangement 3.
• spacers for example in the form of plastic strips, can be used, which ensure a defined distance between the substrate layers 14 and the separator layers 11 before filling. These spacers can be removed after filling in a first subset of the solid particles, but constructions are also possible in which spacer elements (e.g. glass fiber grids) remain in the cell.
• spacer elements e.g. glass fiber grids
• a suspension of the solid particles 17 in a volatile liquid is first introduced into the cell and the liquid is then drawn off (using a vacuum and / or elevated temperature).
• the solid particles 17 can be processed into a pasty mass by means of a binder material, such as, for example, methyl cellulose, with the addition of a liquid is positioned outside the cell housing during assembly of the electrode arrangement 3 between the substrate 14 and the separator 11.
• a binder material such as, for example, methyl cellulose
• the binder can be removed from the layer, for example by the action of temperature. In contrast to a binder remaining in the cell, it does not have to be inert.
• FIG. 5 shows the preferred embodiment already mentioned, in which two fractions of structure-forming solid particles 23, 24 are used to increase the degree of volume filling, the sizes of which complement one another such that the particles 24 of the finer fraction fit into the gusset 25 between the particles of the coarser fraction ,
• the ratio of the average particle size of the two fractions is preferably between about 1: 6 and
• Particles of a middle fraction fit into the gusset between the particles of a coarsest fraction and the particles of a finest fraction fit into the gusset of the middle fraction.
• the particle size is selected by sieving.
• the particle size is therefore defined by the hole size of the sieves used.
• the mean particle size is the average particle size of the size distribution curve of a fraction.
• FIG. 6 shows a particularly preferred embodiment in which the porous structure 16 contains a solid salt 26.
• the salt 26 is preferably in the form of finely divided particles 27 in the porous structure 16 included, the salt particles 27 being so much smaller than the structure-forming solid particles 17 that the salt particles fit into the pores 18 of the porous structure 16.
• the salt particles 27 are preferably very much smaller than the structure-forming particles 17.
• the mean particle sizes of suitable structure-forming particles are between approximately 10 ⁇ m and approximately 200 ⁇ m, values between 50 ⁇ m and 150 ⁇ m being particularly preferred.
• the ratio of the average particle size of the salt to the average particle size of the structure-forming particles 17 should be less than 1: 2, preferably less than 1: 4 and particularly preferably less than 1: 8. If the porous structure 16 contains several particle fractions, the mean value of their average particle sizes weighted according to the amounts of the particle fractions is to be used for this comparison.
• the proportion of the salt particles in the total volume of the solid substances of the porous structure should be low.
• the total volume of the salt particles is preferably at most 20%, preferably at most 10% and particularly preferably at most 5% of the total solid volume of the porous structure.
• the salt is preferably an alkali halide, in particular -LiF, NaCl or LiCl, with LiF being particularly preferred.
• the advantageous effect of a solid salt in contact with the discharge element of the negative electrode of the electrochemical cell is known from WO 00/44061.
• the safety-relevant effect of the salt reference can be made to this document. In the context of the present invention, it was found that the safety of the cells can still be significantly improved if the one provided according to WO 00/44061 loose bed of grains of salt is replaced by a compact porous structure formed from nonionic inert particles and the salt is used only in significantly smaller amounts within this porous structure.
• LiCo ⁇ 2 was used, on the negative electrode of which a quantity of lithium equivalent to 250 mAh was deposited during charging.
• the cell in particular the space between the substrate of the negative electrode and the separator
• the cell was filled with a mixture of two SiC fractions, the particle size of which was restricted to definable size ranges by sieving.
• An addition of LiF was also used.
• the ingredients were dried, mixed and filled in the following proportions:
• the resulting degree of volume filling was approximately 60%.
• the cell was loaded. An artificial internal short circuit was then caused by means of a needle pierced through the electrode (needle test). Result: The deposited lithium grew very regularly into the layer of the porous structure during charging. No growth through to the separator was observed. During the short circuit, partial reaction was only registered in the area of the needle tip. The reaction did not continue from there to other areas of the electrode and there was no flame front. The reaction came to a halt within about two seconds. There was practically no smoke development.
• Cells with the construction according to the invention warmed up after reaching a critical temperature just below 60 ° C. due to a reaction taking place in the cell to about 80 to 90 ° C. and then cooled again to the ambient temperature. After the furnace test, they could be discharged to over 50% of their original loading capacity.

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• General Chemical & Material Sciences (AREA)
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• Composite Materials (AREA)
• Inorganic Chemistry (AREA)
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• 2002
  • 2002-01-19 DE DE10201936A patent/DE10201936A1/de not_active Withdrawn
• 2003
  • 2003-01-16 WO PCT/DE2003/000103 patent/WO2003061036A2/de not_active Ceased
  • 2003-01-16 AU AU2003205523A patent/AU2003205523A1/en not_active Abandoned
  • 2003-01-16 JP JP2003561021A patent/JP4589627B2/ja not_active Expired - Fee Related
  • 2003-01-16 EP EP03702333A patent/EP1481430A2/de not_active Withdrawn
  • 2003-01-16 US US10/501,760 patent/US7901811B2/en not_active Expired - Fee Related
  • 2003-01-16 DE DE10390156T patent/DE10390156D2/de not_active Withdrawn - After Issue

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