EP4342016A1 - Cover assembly for an electrochemical cell, corresponding electrochemical cell and battery - Google Patents

Cover assembly for an electrochemical cell, corresponding electrochemical cell and battery

Info

Publication number
EP4342016A1
EP4342016A1 EP21758747.6A EP21758747A EP4342016A1 EP 4342016 A1 EP4342016 A1 EP 4342016A1 EP 21758747 A EP21758747 A EP 21758747A EP 4342016 A1 EP4342016 A1 EP 4342016A1
Authority
EP
European Patent Office
Prior art keywords
fuse
terminal
cover assembly
electrochemical cell
cavity
Prior art date
Legal status (The legal status is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the status listed.)
Pending
Application number
EP21758747.6A
Other languages
German (de)
French (fr)
Inventor
Sébastien BADET
Gilles Philippe
Ki-Woon Kim
Nikolay Semenov
Current Assignee (The listed assignees may be inaccurate. Google has not performed a legal analysis and makes no representation or warranty as to the accuracy of the list.)
SAFT Societe des Accumulateurs Fixes et de Traction SA
Original Assignee
SAFT Societe des Accumulateurs Fixes et de Traction SA
Priority date (The priority date is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the date listed.)
Filing date
Publication date
Application filed by SAFT Societe des Accumulateurs Fixes et de Traction SA filed Critical SAFT Societe des Accumulateurs Fixes et de Traction SA
Publication of EP4342016A1 publication Critical patent/EP4342016A1/en
Pending legal-status Critical Current

Links

Classifications

    • H—ELECTRICITY
    • H01—ELECTRIC ELEMENTS
    • H01M—PROCESSES OR MEANS, e.g. BATTERIES, FOR THE DIRECT CONVERSION OF CHEMICAL ENERGY INTO ELECTRICAL ENERGY
    • H01M50/00—Constructional details or processes of manufacture of the non-active parts of electrochemical cells other than fuel cells, e.g. hybrid cells
    • H01M50/10—Primary casings; Jackets or wrappings
    • H01M50/147—Lids or covers
    • H01M50/148—Lids or covers characterised by their shape
    • H01M50/15—Lids or covers characterised by their shape for prismatic or rectangular 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
    • H01M10/05—Accumulators with non-aqueous electrolyte
    • H01M10/052—Li-accumulators
    • H01M10/0525—Rocking-chair batteries, i.e. batteries with lithium insertion or intercalation in both electrodes; Lithium-ion batteries
    • H—ELECTRICITY
    • H01—ELECTRIC ELEMENTS
    • H01M—PROCESSES OR MEANS, e.g. BATTERIES, FOR THE DIRECT CONVERSION OF CHEMICAL ENERGY INTO ELECTRICAL ENERGY
    • H01M50/00—Constructional details or processes of manufacture of the non-active parts of electrochemical cells other than fuel cells, e.g. hybrid cells
    • H01M50/10—Primary casings; Jackets or wrappings
    • H01M50/172—Arrangements of electric connectors penetrating the casing
    • H01M50/174—Arrangements of electric connectors penetrating the casing adapted for the shape of the cells
    • H01M50/176—Arrangements of electric connectors penetrating the casing adapted for the shape of the cells for prismatic or rectangular cells
    • H—ELECTRICITY
    • H01—ELECTRIC ELEMENTS
    • H01M—PROCESSES OR MEANS, e.g. BATTERIES, FOR THE DIRECT CONVERSION OF CHEMICAL ENERGY INTO ELECTRICAL ENERGY
    • H01M50/00—Constructional details or processes of manufacture of the non-active parts of electrochemical cells other than fuel cells, e.g. hybrid cells
    • H01M50/50—Current conducting connections for cells or batteries
    • H01M50/528—Fixed electrical connections, i.e. not intended for disconnection
    • H—ELECTRICITY
    • H01—ELECTRIC ELEMENTS
    • H01M—PROCESSES OR MEANS, e.g. BATTERIES, FOR THE DIRECT CONVERSION OF CHEMICAL ENERGY INTO ELECTRICAL ENERGY
    • H01M50/00—Constructional details or processes of manufacture of the non-active parts of electrochemical cells other than fuel cells, e.g. hybrid cells
    • H01M50/50—Current conducting connections for cells or batteries
    • H01M50/543—Terminals
    • H01M50/552—Terminals characterised by their shape
    • H—ELECTRICITY
    • H01—ELECTRIC ELEMENTS
    • H01M—PROCESSES OR MEANS, e.g. BATTERIES, FOR THE DIRECT CONVERSION OF CHEMICAL ENERGY INTO ELECTRICAL ENERGY
    • H01M50/00—Constructional details or processes of manufacture of the non-active parts of electrochemical cells other than fuel cells, e.g. hybrid cells
    • H01M50/50—Current conducting connections for cells or batteries
    • H01M50/572—Means for preventing undesired use or discharge
    • H01M50/574—Devices or arrangements for the interruption of current
    • H01M50/583—Devices or arrangements for the interruption of current in response to current, e.g. fuses
    • H—ELECTRICITY
    • H01—ELECTRIC ELEMENTS
    • H01M—PROCESSES OR MEANS, e.g. BATTERIES, FOR THE DIRECT CONVERSION OF CHEMICAL ENERGY INTO ELECTRICAL ENERGY
    • H01M50/00—Constructional details or processes of manufacture of the non-active parts of electrochemical cells other than fuel cells, e.g. hybrid cells
    • H01M50/50—Current conducting connections for cells or batteries
    • H01M50/543—Terminals
    • H01M50/552—Terminals characterised by their shape
    • H01M50/553—Terminals adapted for prismatic, pouch or rectangular cells
    • 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 present invention concerns a cover assembly for a secondary electrochemical cell, comprising
  • the terminal assembly comprising:
  • terminal base adapted to be electrically connected to a collector of the electrochemical cell
  • a fuse adapted to melt when subject to a determined rated electrical current and/or a determined rated electrical voltage.
  • An electrochemical cell or electrochemical generator is a device for generating electricity in which chemical energy is converted into electrical energy.
  • the chemical energy consists of electrochemically active compounds deposited on at least one side of electrodes arranged in the electrochemical generator.
  • the electrical energy is produced by electrochemical reactions during a discharge of the electrochemical generator.
  • the electrodes, arranged in a container, are electrically connected to current output terminals that provide electrical continuity between the electrodes and an electrical consumer with which the electrochemical generator is associated.
  • the positive and negative current output terminals may be attached either to the walls of opposite faces of the container of the electrochemical generator, or to the wall of a single face of the container.
  • electrochemical generators can be connected together in series or in parallel depending on the nominal operating voltage of the electrical consumer and the amount of energy intended to be supplied to that consumer.
  • the electrochemical generators are then placed in a common housing and the housing and the plurality of electrochemical generators contained therein are generally referred to as a battery.
  • the positive and negative current output terminals are often attached to the wall of the same side of the container, often to a cover intended to close the generator container.
  • An anomaly in the operation of the battery can be caused by the malfunction of one of the electrochemical generators (short circuit, overload,...) or by an external disturbance (shock, rise in temperature, etc.) or by a failure of the electronic system managing the state of charge or other parameters of the battery generators.
  • a lithium-ion electrochemical generator when a lithium-ion electrochemical generator is subjected to an overcharge, its temperature rises. The increase in temperature causes an increase in charging current, which further promotes the temperature increase. If the generator does not have a sufficient cooling system to remove the heat emitted, it will go into a thermal runaway situation: the temperature increase is fed by the generator itself.
  • Cover assemblies for secondary cells comprising terminal assemblies are known, for example from EP2816637.
  • This document discloses a rechargeable battery comprising a cap assembly and collector plates.
  • the battery includes a terminal that carries a first fuse part.
  • One of the collector plates comprises a coupling part, an extension part a terminal hole a fuse hole and a fuse protrusion.
  • the fuse hole extends in a fuse region of the collector plate forming a second fuse part. During a short circuit in the battery, the fuse part melts and subsequently the fuse region.
  • the cover assembly of this document is rather difficult to manufacture, in particular to assemble. Also, the melted metal of the fuses in the known electrochemical cell is not constrained and might cause further malfunctions.
  • FR2743452 discloses a security device for an electrochemical generator.
  • the position and configuration of the fuse cavity should be determined even after melting of the fuse.
  • the invention relates to a cover assembly as defined by claim 1 .
  • cover assembly according to the invention may comprise one or more of the following features, taken alone or together in all technically possible combinations:
  • the cover assembly comprises a trigger device adapted to trigger the fuse when a predetermined temperature and/or a predetermined pressure is reached, in particular the trigger device being adapted to short circuit a negative and a positive electrode of the electrochemical cell via the fuse.
  • the fuse cavity comprises one or more of the following features:
  • the fuse cavity is arranged in the terminal base
  • the fuse cavity is open to a side opposite the terminal plate
  • the fuse cavity has a volume at least identical to a volume of the fuse
  • the fuse cavity is arranged below the fuse.
  • Either the fuse and the terminal base are one piece or the fuse and the terminal base are two distinct pieces.
  • the fuse provides in the unmelted state a mechanical connection of the terminal plate and the terminal base, the fuse is adapted to, when melting, mechanically separate the terminal plate from the terminal base and the terminal assembly comprises a retaining element holding the terminal plate with respect to the terminal base in absence of the mechanical connection of the terminal plate and the terminal base when the fuse is melted.
  • the retaining element comprises retaining members cooperating by complementarity of shape with at least one retaining cavity provided in the terminal plate and/or in the terminal base.
  • the retaining members comprise projections and the retaining cavity comprises at least one recess.
  • the retaining element is made from plastic, in particular from PPS (Polyphenylene Sulfide), PP (Polypropylene), PBT (Polybutylene Terephthalate) and PFA (Perfluoroalkoxy).
  • PPS Polyphenylene Sulfide
  • PP Polypropylene
  • PBT Polybutylene Terephthalate
  • PFA Perfluoroalkoxy
  • the terminal assembly comprises a screw including a screw shaft, in particular a screw according to an industry standard such as a DIN ISO screw, the terminal plate and the terminal base are fastened one to another by the screw, in particular the screw shaft comprising a screw portion and the terminal base comprising a threaded cavity into which the screw portion is screwed, and the fuse is a fuse portion of the screw, in particular a portion of the screw shaft.
  • the fuse portion is a recessed portion of the screw shaft and/or the fuse cavity is delimited by the recessed portion of the screw shaft.
  • a further object of the invention is an electrochemical cell, in particular secondary cell, notably a Lithium-Ion electrochemical cell, comprising
  • cover assembly is a cover assembly according as defined above.
  • a further object is a battery, comprising
  • each of the electrochemical cells and the trigger device being adapted to short circuit the negative and the positive electrode of the associated electrochemical cell via the fuse, the positive electrodes of each of the electrochemical cells being electrically connected together and the negative electrodes of each of the electrochemical cells being electrically connected together, the electrochemical cells thus being connected in parallel so that the battery is adapted to short circuit the positive electrode and the negative electrode of each of the electrochemical cells through the trigger device upon triggering of the trigger device.
  • each functional feature of a disclosed object should be understood as disclosing the corresponding method step during use of the object.
  • FIG. 1 a schematic drawing of an electric circuit comprising an electrochemical cell according to the present invention
  • FIG. 2 is a schematic view of an electrochemical cell according to the present invention, the electrochemical cell cover being shown in detail;
  • Figure 3 is a longitudinal cut through the electrochemical cell cover of Figure 2;
  • FIG. 4 is an exploded view of the electrochemical cell cover of Figures 2 and 3;
  • FIG. 5 is an enlarged view of detail V of figure 3;
  • FIG. 6 is a view corresponding to that of Figure 5 of a variant of the electrochemical cell cover of Figures 2 to 5.
  • FIG. 7 is a schematic view of a portion of a cover assembly according to an embodiment of the invention.
  • FIG. 8 is a schematic view of a cover assembly according to a variant of the embodiment of Figure 7.
  • FIG. 1 shows schematically a system 2 or electric circuit according to the invention.
  • the system 2 comprises two electrochemical cells 4, also called battery cells 4, electrically connected in parallel to a charging device or a consumer 6.
  • the electrochemical cells 4 are part of a battery, which comprises the electrochemical cells and for example a container containing the electrochemical cells.
  • the number of electrochemical cells 4 differ according to the desired voltage and capacity of the battery.
  • the electrochemical cells 4 are in particular a secondary electrochemical cell, notably a Lithium-Ion electrochemical cell.
  • the electrochemical cells 4 comprise each a negative electrode 10, a positive electrode 12 and a separator 14 interposed between the electrodes 10, 12.
  • the negative electrode 10 is electrically connected to a negative terminal 16 and the positive electrode 12 is electrically connected to a positive terminal 18.
  • the negative electrode 10 comprises a negative electrode tab 20 and the positive electrode 12 comprises a positive electrode tab 22.
  • the negative electrode tab 20 is fixed, for example welded or soldered, to a negative current collector 24 and the positive electrode tab 22 is fixed, for example welded or soldered to a positive current collector 26.
  • the negative current collector 24 is electrically connected via a negative connector 28 to the negative terminal 10 and the positive current collector 26 is electrically connected via a positive connector 30 to the positive terminal 18.
  • the electrochemical cell 4 comprises a casing or case 32 and a cover assembly or lid assembly 34 closing the casing 32.
  • the cover assembly 34 comprises a cover plate 36, the negative terminal 16 and the positive terminal 18.
  • the cover assembly 34 comprises also a trigger device 38 adapted to trigger a fuse 54 (see below) when a predetermined temperature or a predetermined pressure is reached or exceeded within the casing 32. More particularly, the trigger device 38 is adapted to short circuit the negative electrode 10 and the positive electrode 12 of the electrochemical cell 4 via the fuse 54 (see below).
  • the trigger device 38 is for example a pressure detection device adapted to short circuit the negative and positive electrodes in case of a pressure excess within the battery casing. In addition, or alternatively, the trigger device 38 is a temperature detection device adapted to short circuit the negative and positive electrodes in case of a temperature excess within the battery case.
  • the trigger device 38 comprises to this end for example pressure-sensitive membranes or temperature-sensitive metallic membranes that deform under changing pressures or temperatures.
  • the trigger device 38 comprises pressure and temperature sensitive membranes that deform upon the change of pressure and temperature.
  • the predetermined temperature is a temperature reached under condition outside normal operating conditions, such as thermal runaway. This temperature is for example above 100°C.
  • the predetermined pressure is a pressure reached under condition outside normal operating conditions, such as overcharging. This pressure is for example between 5 and 7bar.
  • the cover plate 36 extends generally along a cover plane CP, the outer surface of the cover plate being parallel to the cover plane CP. The cover plate 36 defines an outside of the electrochemical cell and an inside of the electrochemical cell.
  • the cover assembly 34 comprises a positive terminal assembly 40 and a negative terminal assembly 42.
  • the positive terminal assembly 40 comprises a terminal plate 50, a terminal base 52, a fuse 54, and a retaining element 56 (see in particular Figure 5).
  • the terminal plate 50 is adapted to be brought in contact with a (not shown) connector.
  • the terminal plate 50 may be a plate extending parallel to the cover plane CP and may be made from Aluminum.
  • the terminal base 52 is adapted to be electrically connected to the positive collector of the electrochemical cell and is electrically connected to it in the present case.
  • the terminal base 52 may be a plate extending parallel to the cover plane CP.
  • the fuse 54 is adapted to melt when subject to a determined rated electrical current and/or rated electrical voltage or when these current and/or voltage are exceeded for a determined time.
  • the fuse 54 in the unmelted state, provides an electrical connection of the terminal plate 50 with the terminal base 52 and provides advantageously a mechanical connection of the terminal plate and the terminal base.
  • the fuse 54 when the fuse 54 is in a state before being triggered, the terminal plate 50 and the terminal base 52 are fixed one to another by the fuse 54.
  • the fuse 54 is adapted to when melting, electrically, and advantageously also mechanically, separate the terminal plate from the terminal base. Thus, once triggered, the fuse 54 melts and, in absence of any other retaining element, the terminal plate 50 and the terminal base 54 are separated one from another.
  • the terminal plate 50 comprises a terminal disc 58 and a terminal head 60.
  • the terminal disc 58 and the terminal head 60 are fixed one to another, for example by plastic deformation and/or by soldering and/or by welding.
  • the terminal head is a rivet head riveted to a fixing hole 62 in the terminal disc and the riveted terminal head is welded to the terminal disc.
  • the terminal base 52 comprises a base disc 64.
  • the fuse 54 is a portion having a material, a cross section and a thickness such that it melts under the determined specification.
  • the fuse 54 may be made of aluminum.
  • the fuse 54 may be an annular disc with an external diameter of 2,0 to 2,5mm and an inner diameter of 1 ,0mm to 1 ,5mm and having a thickness of 0,1 mm to 0,3mm. The actual dimensions are however determined by the necessary sensitivity of the fuse and can be determined by the person skilled in the art without difficulty.
  • the fuse is a cylindrical portion.
  • the terminal base 52, respectively the base disc 64, the fuse 54 and the terminal head 60 are advantageously made in one piece, for example by casting and/or laser cutting.
  • the fuse 54 and the terminal base 52 are made from one piece.
  • the fuse 54 and the terminal base 52 are two distinct pieces.
  • the positive terminal assembly 40 further comprises the retaining element 56 holding the terminal plate 50 with respect to the terminal base 52 in absence of the mechanical connection of the terminal plate and the terminal base when the fuse 54 is or has been melted.
  • the terminal plate 50 and the terminal base 52 comprise each a retaining cavity 68, respectively 70 (see Figure 5).
  • the retaining cavity is in the present case a circular groove defined by the terminal plate 50 and by the terminal base 52.
  • Each retaining cavity defines an undercut in the direction perpendicular to the direction of separation of the terminal plate 50 and the terminal base 52, i.e. perpendicular to the cover plane CP.
  • the retaining element 56 comprises retaining members 72, 74, presently two annular rims, cooperating by complementary of shape (in German: “form gleichig”) with the corresponding retaining cavity 68, 70.
  • the annular rims project radially inwardly.
  • the retaining members and retaining cavities that cooperate by complementarity of shape may have other shapes, such as pins and holes or indented shapes having matching negative/positive profiles or any other projections and recesses.
  • the retaining element 56 comprises a central disc engaging in a groove that separates the terminal head and the terminal base 52.
  • the retaining members 72, 74 are arranged axially spaced from the central disc on an annular cylinder arranged on the outside of the central disc.
  • the retaining element 56 is advantageously made from plastic, for example from PPS (Polyphenylene Sulfide), PP (Polypropylene), PBT (Polybutylene Terephthalate), and PFA (Perfluoroalkoxy).
  • PPS Polyphenylene Sulfide
  • PP Polypropylene
  • PBT Polybutylene Terephthalate
  • PFA Perfluoroalkoxy
  • the positive terminal assembly 40 comprises a fuse cavity 80 adapted to receive the molten fuse material.
  • the fuse cavity 80 is a cavity arranged in the terminal base 52 adjacent to the fuse 54.
  • the fuse cavity 80 has advantageously a size and shape adapted to receive enough molten fuse material so as to avoid accidental reconnection of the terminal base and the terminal plate even after the fuse 54 has been triggered. Such an accidental reconnection could happen in the known terminal assemblies for example by insufficient drain of the molten fuse material.
  • the fuse cavity 80 has a volume at least identical to the volume of the fuse 54.
  • the fuse cavity 80 is open to a side opposite the terminal plate 50, as the molten fuse material may be drained from the terminal assembly.
  • the fuse cavity 80 is closed and adapted to contain the molten fuse material.
  • the fuse cavity 80 is arranged below the fuse 54, in an operational position of the battery.
  • the terminal plate 50 is arranged above the terminal base 52 during operation of the battery.
  • the cover assembly 34 comprises furthermore a gasket 82 arranged between the cover plate 36 and the terminal base 52 and sealing the inside of the case 32 with respect to the outside of the case 32 at the location of the retaining element 56.
  • the cover plate 36 comprises in the present case two superposed partial cover plates 84, 86 that are assembled together (see Figure 4).
  • a conduction sheet 88 is interposed between the terminal plate 50 and the cover plate 36.
  • the negative terminal assembly 42 has a structure that is similar to the positive terminal assembly 40, with the following differences, that are depicted on Figure 4.
  • the negative terminal assembly includes a negative terminal plate 90, a base plate 92, a retainer plate 96, and a gasket 98.
  • the negative terminal assembly 42 includes elements of the trigger device 38, in particular a pressure membrane 99 ( Figure 4).
  • the negative terminal assembly does not comprise a fuse 54 as the positive terminal assembly.
  • the negative terminal assembly incorporates a fuse identical to the fuse of the positive terminal assembly disclosed above.
  • the corresponding functional elements of the positive terminal assembly such as the terminal plate, base plate, fuse cavity and retaining element and their structural relations, are adapted to the shape and function of the negative terminal assembly.
  • the negative terminal assembly comprises a fuse but not the positive terminal assembly.
  • Figure 6 shows a variant of the positive terminal assembly 40 of the embodiment of figures 1 to 5. This variant differs only in the following features, same or similar features bearing identical reference numbers. Any of the following features may be applied to the foregoing embodiment individually and is not necessarily linked to the remaining features of the variant, but may provide particular advantages in combination.
  • the fuse 54 is not an annular disc, but a cylindrical portion having a determined cross section.
  • the cylindrical portion may have a cross section comprised between 0.7 mm 2 and 2 mm 2 and a length comprised between 0.3 mm and 2 mm. These values are at least applicable to an NMC/Graphite element of 40 to 50Ah.
  • the cylindrical portion may be made from aluminum or copper.
  • the retaining element 56 is attached to the terminal base 52 by corresponding cylindrical surfaces having an interference fit, i.e. by friction only (in German: “reibschlCissig”), instead of complementary of shape. Further, the retaining element 56 is attached to the terminal plate 50 respectively the terminal head 60 by corresponding cylindrical surfaces having an interference fit, i.e. by friction only (in German: “reibschlCissig”), instead of complementary of shape.
  • the terminal base 52 remains attached to the terminal head 60 and the terminal plate via the retaining element 56.
  • one of the attachments of the terminal base 52 to the retaining element 56 and the terminal plate 50 or the terminal head 60 to the retaining element may be an interference fit as in Figure 6 and the other of these attachments may be by complementary of shape as in Figure 5.
  • the terminal base 52 has a fuse cavity 80 similar to the one of the variant of Figure 5.
  • the retaining element 56 is arranged at a distance of the fuse 54 and these two elements enclose an annular space that is void.
  • the annular space supports preventing reconnection after melting of the fuse. It also helps the fuse melt down and be mixed with portions of the retaining element 56, thus preventing reconnection.
  • the annular space may have other shapes.
  • the retaining element 56 comprises to this end a dilution portion that is adjacent to the fuse and is able to be molten by the molten fuse material and is able to mix with this molten fuse material.
  • Figure 7 is a schematic view in cross section of a portion of a cover assembly according to an embodiment of the invention. The view corresponds essentially to the view of Figure 5.
  • This embodiment differs only in the following features from the embodiment of Figures 1 to 5, same or similar features comprising bearing reference numbers. Any of the following features may be applied to the foregoing embodiment individually and is not necessarily linked to the remaining features of the variant, but may provide particular advantages with in combination.
  • the terminal plate 50, respectively the terminal disc 58, and the terminal base 52, respectively the base disc 64, are fastened one to another by a screw 100.
  • the screw 100 comprises a screw head 60 engaging with the terminal disc 58.
  • the screw 100 comprises a screw shaft 102 having a threaded screw portion 104.
  • the screw shaft 102 is screwed into a threaded cavity 106 of the base disc 64.
  • the screw 100 comprises the fuse 54, which extends between the screw head 60 and the screw shaft 102.
  • the fuse 54 is a fuse portion 108 of the screw shaft 102 having a determined electrical resistance.
  • the fuse portion 108 may thus have the electrical features of the fuses 54 disclosed with respect to the remaining embodiments.
  • the screw 100 may be a screw according to an industry standard, such as a DIN ISO screw or such as a screw CFIC DIN 912 or DIN EN ISO 4762.
  • the terminal disc 58 may be made from aluminum.
  • the base disc 64 may be made from aluminum, in particular in case the terminal is a negative terminal, or from copper, in particular in case the terminal is a positive terminal.
  • the screw 100 or at least a part of the screw, in particular the head 60, may be made from aluminum.
  • the base disc 64 of positive terminal should be aluminum and the base disc 64 of negative terminal should be copper due to electrochemical compatibility inside a cell. Both of positive and negative terminal discs 58 are good to be aluminum for module assembly. If the base disc 64 is copper and the terminal disc 58 is aluminum in a negative terminal, welding these two elements is expensive due to the copper/aluminum junction.
  • the present embodiment comprising a screw 100 does not need a weld of copper/aluminum and comprises a copper base disc 64, aluminum terminal disc 58 and aluminum screw 100 which is an economic combination.
  • the terminal 50 comprises also a diluting insert 110 surrounding the fuse portion 108.
  • the diluting insert 110 is adjacent to the fuse portion 108 and may be made from a non-conductive material that has a melting temperature inferior to the melting temperature of the fuse portion 108.
  • the fuse portion is a recessed portion of the screw shaft, in particular is an annular groove.
  • the diluting insert 110 is made from a conductive plastic having an electric conductivity lower than the electric conductivity of the fuse in the non-melted state, but an electric conductivity resulting in an electric resistance higher than that of the electric resistance of the fuse, ideally more than 10000 times higher.
  • the diluting insert 110 is for example made from PPS (Polyphenylene Sulfide), which has the advantage of being compatible with electrolyte, even though it might not necessarily contact the electrolyte.
  • PPS Polyphenylene Sulfide
  • Any electrolyte compatible plastics can be used, such as PP (Polypropylene), PBT (Polybutylene Terephthalate), and PFA (Perfluoroalkoxy).
  • the diluting insert 110 In case a conductive plastic, is used for the diluting insert 110, when the fuse is activated there will remain an electrical path via the diluting insert 110 between the negative electrode and the positive electrode, but with a very high electric resistance (>100 Ohms). When the membrane is activated and once the fuse is melted, the cell put in a very slow short-circuit via the diluting insert 110, so the electrochemical cell is discharging slowly itself removing the remaining energy from the electrodes.
  • the diluting insert 110 When the fuse portion 108 melts, the diluting insert 110 is also at least partially melted and mixes with the melted fuse metal. The resulting metal/non-conductive material mix is electrically non-conductive and avoids a reconnection of the terminal plate and the terminal base 52. To prevent reconnection again, a void exists between the fuse 108 and the diluting insert 110, enhancing the mixture of molten fuse and molten diluting insert.
  • a screw 100 for attaching the elements of the terminal assembly together is advantageous, as no welding or brazing of potentially incompatible materials is necessary. Also, the screw 100 is an economic item. Alternatively, the screw may be replaced by another element, for example a clip having a fuse portion. Generally, the fuse 54 and the terminal base 52 may be two distinct pieces.
  • FIG. 8 shows also a fuse portion 108 that is a recessed portion of the screw shaft, in particular is an annular groove.
  • the battery or the system 2 work in the following manner.
  • a thermal incident in a defect electrochemical cells 4 starts, the pressure inside the electrochemical cell 4 increases and triggers the trigger device 38, thus short circuiting the electrodes of the defected electrochemical cell 4 via the fuse 54.
  • the fuse 54 of the defected electrochemical cell 4 melts and the electrodes of the defected electrochemical cell 4 is disconnected from the remainder of the electrochemical cells 4.
  • the electrochemical cells 4 are connected one to another in parallel, during the short-circuit of the defected electrochemical cell 4, the remaining electrochemical cells 4 are short-circuited via the trigger device 38 of the defected electrochemical cell 4. This leads to an activation of the fuses of the remaining electrochemical cells 4, which disconnect in turn the electrodes of all the remaining electrochemical cells 4 from the circuit.
  • the fuses of the remainder of the electrochemical cells are thus also blown, thus totally incapacitating the battery or system 2 and putting it into a safe condition.

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  • Chemical & Material Sciences (AREA)
  • Chemical Kinetics & Catalysis (AREA)
  • Electrochemistry (AREA)
  • General Chemical & Material Sciences (AREA)
  • Engineering & Computer Science (AREA)
  • Materials Engineering (AREA)
  • Manufacturing & Machinery (AREA)
  • Connection Of Batteries Or Terminals (AREA)

Abstract

This cover assembly for a secondary electrochemical cell comprises a cover plate (36), a negative terminal (16), a positive terminal (18). The negative terminal or the positive terminal comprises a terminal assembly (40), which comprises a terminal plate (50) adapted to be brought in contact with a connector; a terminal base (52) adapted to be electrically connected to a collector of the electrochemical cell; and a fuse (54) adapted to melt when subject to a determined rated electrical current and/or a determined rated electrical voltage. The fuse provides in the unmelted state an electrical connection of the terminal plate with the terminal base. The fuse (54) is adapted to, when melting, electrically separate the terminal plate from the terminal base and, upon melting, becoming molten fuse material. The terminal assembly comprises a fuse cavity (80) adapted to receive the molten fuse material.

Description

Cover assembly for an electrochemical cell, corresponding electrochemical cell and battery
The present invention concerns a cover assembly for a secondary electrochemical cell, comprising
- a cover plate,
- a negative terminal,
- a positive terminal, at least one of the negative terminal or the positive terminal comprising a terminal assembly, the terminal assembly comprising:
- a terminal plate adapted to be brought in contact with a connector;
- a terminal base adapted to be electrically connected to a collector of the electrochemical cell; and
- a fuse adapted to melt when subject to a determined rated electrical current and/or a determined rated electrical voltage.
An electrochemical cell or electrochemical generator is a device for generating electricity in which chemical energy is converted into electrical energy. The chemical energy consists of electrochemically active compounds deposited on at least one side of electrodes arranged in the electrochemical generator. The electrical energy is produced by electrochemical reactions during a discharge of the electrochemical generator. The electrodes, arranged in a container, are electrically connected to current output terminals that provide electrical continuity between the electrodes and an electrical consumer with which the electrochemical generator is associated. The positive and negative current output terminals may be attached either to the walls of opposite faces of the container of the electrochemical generator, or to the wall of a single face of the container.
Several electrochemical generators can be connected together in series or in parallel depending on the nominal operating voltage of the electrical consumer and the amount of energy intended to be supplied to that consumer. The electrochemical generators are then placed in a common housing and the housing and the plurality of electrochemical generators contained therein are generally referred to as a battery. For convenience of electrical connection between electrochemical generators placed in a battery, the positive and negative current output terminals are often attached to the wall of the same side of the container, often to a cover intended to close the generator container.
An anomaly in the operation of the battery can be caused by the malfunction of one of the electrochemical generators (short circuit, overload,...) or by an external disturbance (shock, rise in temperature, etc.) or by a failure of the electronic system managing the state of charge or other parameters of the battery generators. For example, when a lithium-ion electrochemical generator is subjected to an overcharge, its temperature rises. The increase in temperature causes an increase in charging current, which further promotes the temperature increase. If the generator does not have a sufficient cooling system to remove the heat emitted, it will go into a thermal runaway situation: the temperature increase is fed by the generator itself. The uncontrolled increase in the temperature of the generator leads to the generation of gases that can cause an increase in the internal pressure in the generator, which will open a safety system to evacuate the gases. In case of release of hot gases, whose temperature can reach 650°C, these gases come into contact with the other generators of the battery. There is then a risk that the thermal runaway phenomenon will spread to all the generators in the battery, leading to the total destruction of the battery.
Cover assemblies for secondary cells comprising terminal assemblies are known, for example from EP2816637. This document discloses a rechargeable battery comprising a cap assembly and collector plates. The battery includes a terminal that carries a first fuse part. One of the collector plates comprises a coupling part, an extension part a terminal hole a fuse hole and a fuse protrusion.
The fuse hole extends in a fuse region of the collector plate forming a second fuse part. During a short circuit in the battery, the fuse part melts and subsequently the fuse region.
The cover assembly of this document is rather difficult to manufacture, in particular to assemble. Also, the melted metal of the fuses in the known electrochemical cell is not constrained and might cause further malfunctions.
Another secondary battery is known from EP2399669. FR2743452 discloses a security device for an electrochemical generator.
It is an objective of the invention to improve the security of secondary cells and secondary batteries and this with economic means.
Further particular objectives of the present invention include:
Once the fuse is melted, a reconnection of the terminals should be reliably avoided, in order to ensure that the electrochemical cell keeps being disconnected.
The position and configuration of the fuse cavity should be determined even after melting of the fuse.
In case of parallel electrical connection of the electrochemical cell with other electrochemical cells and in case of a thermal incident, the propagation of the thermal incident to neighboring electrochemical cells needs to be delayed.
Further, it should be avoided that the defect electrochemical cell discharges itself to the electrochemical cells with which it is connected. In order to achieve at least one of the above objects, the invention relates to a cover assembly as defined by claim 1 .
According to specific embodiments, the cover assembly according to the invention may comprise one or more of the following features, taken alone or together in all technically possible combinations:
- The cover assembly comprises a trigger device adapted to trigger the fuse when a predetermined temperature and/or a predetermined pressure is reached, in particular the trigger device being adapted to short circuit a negative and a positive electrode of the electrochemical cell via the fuse.
The fuse cavity comprises one or more of the following features:
- the fuse cavity is arranged in the terminal base,
- the fuse cavity is open to a side opposite the terminal plate,
- the fuse cavity has a volume at least identical to a volume of the fuse,
- the fuse cavity is arranged below the fuse.
Either the fuse and the terminal base are one piece or the fuse and the terminal base are two distinct pieces.
The fuse provides in the unmelted state a mechanical connection of the terminal plate and the terminal base, the fuse is adapted to, when melting, mechanically separate the terminal plate from the terminal base and the terminal assembly comprises a retaining element holding the terminal plate with respect to the terminal base in absence of the mechanical connection of the terminal plate and the terminal base when the fuse is melted.
- The retaining element comprises retaining members cooperating by complementarity of shape with at least one retaining cavity provided in the terminal plate and/or in the terminal base.
- The retaining members comprise projections and the retaining cavity comprises at least one recess.
- The retaining element is made from plastic, in particular from PPS (Polyphenylene Sulfide), PP (Polypropylene), PBT (Polybutylene Terephthalate) and PFA (Perfluoroalkoxy).
- The terminal assembly comprises a screw including a screw shaft, in particular a screw according to an industry standard such as a DIN ISO screw, the terminal plate and the terminal base are fastened one to another by the screw, in particular the screw shaft comprising a screw portion and the terminal base comprising a threaded cavity into which the screw portion is screwed, and the fuse is a fuse portion of the screw, in particular a portion of the screw shaft. - The fuse portion is a recessed portion of the screw shaft and/or the fuse cavity is delimited by the recessed portion of the screw shaft.
A further object of the invention is an electrochemical cell, in particular secondary cell, notably a Lithium-Ion electrochemical cell, comprising
- a case,
- a cover assembly closing the case,
- a positive electrode,
- a negative electrode, and
- a separator interposed between the positive electrode and the negative electrode wherein the cover assembly is a cover assembly according as defined above.
A further object is a battery, comprising
Two, or more than two, electrochemical cells as defined above, the cover assembly of each of the electrochemical cells and the trigger device being adapted to short circuit the negative and the positive electrode of the associated electrochemical cell via the fuse, the positive electrodes of each of the electrochemical cells being electrically connected together and the negative electrodes of each of the electrochemical cells being electrically connected together, the electrochemical cells thus being connected in parallel so that the battery is adapted to short circuit the positive electrode and the negative electrode of each of the electrochemical cells through the trigger device upon triggering of the trigger device.
It is contemplated that the various features set forth in the preceding paragraphs, in the claims and/or in the following description and drawings may be taken independently or in any combination thereof. For example, features disclosed in connection with one embodiment are applicable to all embodiments, except where there is technical incompatibility of features.
Furthermore, the statements contained in the description relate to particular embodiments and are not to be construed as limitations on the scope of the invention or on the definition of terms used in the claims, except where a term or phrase is expressly defined. Various other embodiments and various changes and modifications to the disclosed embodiment(s) will become apparent to those skilled in the art. All such other embodiments, changes, and modifications are intended to come within the scope of the appended claims.
Also, where a group of features is disclosed, this disclosed group should also be considered as disclosing any sub-group that is technically possible. As used in this specification and claims, the terms “for example,” “for instance,” “such as,” and “like,” and the verbs “comprising,” “having,” “including,” and their other verb forms, when used in conjunction with a listing of one or more components or other items, are each to be construed as open-ended, meaning that the listing is not to be considered as excluding other, additional components or items. Other terms are to be construed using their broadest reasonable meaning unless they are used in a context that requires a different interpretation.
Also, each functional feature of a disclosed object, as disclosed for example by “adapted to” or “for”, should be understood as disclosing the corresponding method step during use of the object.
The expressions “isolation”, “conductivity”, and the like, which exist as mechanical, thermal or electrical features, are to be interpreted as electrical features only in the present specification, unless specified otherwise.
The invention will be better understood in light of the following specification, which refers to the annexed figures which show:
- Figure 1 a schematic drawing of an electric circuit comprising an electrochemical cell according to the present invention;
- Figure 2 is a schematic view of an electrochemical cell according to the present invention, the electrochemical cell cover being shown in detail;
- Figure 3 is a longitudinal cut through the electrochemical cell cover of Figure 2;
- Figure 4 is an exploded view of the electrochemical cell cover of Figures 2 and 3;
- Figure 5 is an enlarged view of detail V of figure 3;
- Figure 6 is a view corresponding to that of Figure 5 of a variant of the electrochemical cell cover of Figures 2 to 5.
- Figure 7 is a schematic view of a portion of a cover assembly according to an embodiment of the invention, and
- Figure 8 is a schematic view of a cover assembly according to a variant of the embodiment of Figure 7.
Figure 1 shows schematically a system 2 or electric circuit according to the invention. The system 2 comprises two electrochemical cells 4, also called battery cells 4, electrically connected in parallel to a charging device or a consumer 6.
The electrochemical cells 4 are part of a battery, which comprises the electrochemical cells and for example a container containing the electrochemical cells.
The number of electrochemical cells 4 differ according to the desired voltage and capacity of the battery. The electrochemical cells 4 are in particular a secondary electrochemical cell, notably a Lithium-Ion electrochemical cell. The electrochemical cells 4 comprise each a negative electrode 10, a positive electrode 12 and a separator 14 interposed between the electrodes 10, 12. The negative electrode 10 is electrically connected to a negative terminal 16 and the positive electrode 12 is electrically connected to a positive terminal 18. The negative electrode 10 comprises a negative electrode tab 20 and the positive electrode 12 comprises a positive electrode tab 22. The negative electrode tab 20 is fixed, for example welded or soldered, to a negative current collector 24 and the positive electrode tab 22 is fixed, for example welded or soldered to a positive current collector 26. These elements are known as such and are depicted only in a schematic manner in Figure 2.
The negative current collector 24 is electrically connected via a negative connector 28 to the negative terminal 10 and the positive current collector 26 is electrically connected via a positive connector 30 to the positive terminal 18.
The electrochemical cell 4 comprises a casing or case 32 and a cover assembly or lid assembly 34 closing the casing 32.
The cover assembly 34 comprises a cover plate 36, the negative terminal 16 and the positive terminal 18. The cover assembly 34 comprises also a trigger device 38 adapted to trigger a fuse 54 (see below) when a predetermined temperature or a predetermined pressure is reached or exceeded within the casing 32. More particularly, the trigger device 38 is adapted to short circuit the negative electrode 10 and the positive electrode 12 of the electrochemical cell 4 via the fuse 54 (see below). The trigger device 38 is for example a pressure detection device adapted to short circuit the negative and positive electrodes in case of a pressure excess within the battery casing. In addition, or alternatively, the trigger device 38 is a temperature detection device adapted to short circuit the negative and positive electrodes in case of a temperature excess within the battery case.
The trigger device 38 comprises to this end for example pressure-sensitive membranes or temperature-sensitive metallic membranes that deform under changing pressures or temperatures. Alternatively, the trigger device 38 comprises pressure and temperature sensitive membranes that deform upon the change of pressure and temperature.
The predetermined temperature is a temperature reached under condition outside normal operating conditions, such as thermal runaway. This temperature is for example above 100°C. The predetermined pressure is a pressure reached under condition outside normal operating conditions, such as overcharging. This pressure is for example between 5 and 7bar. The cover plate 36 extends generally along a cover plane CP, the outer surface of the cover plate being parallel to the cover plane CP. The cover plate 36 defines an outside of the electrochemical cell and an inside of the electrochemical cell.
The cover assembly 34 comprises a positive terminal assembly 40 and a negative terminal assembly 42.
The positive terminal assembly 40 comprises a terminal plate 50, a terminal base 52, a fuse 54, and a retaining element 56 (see in particular Figure 5).
The terminal plate 50 is adapted to be brought in contact with a (not shown) connector. The terminal plate 50 may be a plate extending parallel to the cover plane CP and may be made from Aluminum.
The terminal base 52 is adapted to be electrically connected to the positive collector of the electrochemical cell and is electrically connected to it in the present case.
The terminal base 52 may be a plate extending parallel to the cover plane CP.
The fuse 54 is adapted to melt when subject to a determined rated electrical current and/or rated electrical voltage or when these current and/or voltage are exceeded for a determined time. The fuse has at least a rated electrical current of lrated=10C/h, where C is the capacity of the electrochemical cell 4 in Ah. For example, for an electrochemical cell of 50Ah, the fuse does not melt under a current of less than 500A.
When the fuse 54 melts, it becomes molten fuse material.
The fuse 54, in the unmelted state, provides an electrical connection of the terminal plate 50 with the terminal base 52 and provides advantageously a mechanical connection of the terminal plate and the terminal base. Thus, when the fuse 54 is in a state before being triggered, the terminal plate 50 and the terminal base 52 are fixed one to another by the fuse 54.
The fuse 54 is adapted to when melting, electrically, and advantageously also mechanically, separate the terminal plate from the terminal base. Thus, once triggered, the fuse 54 melts and, in absence of any other retaining element, the terminal plate 50 and the terminal base 54 are separated one from another.
In the present embodiment, the above features are implemented as follows.
The terminal plate 50 comprises a terminal disc 58 and a terminal head 60. The terminal disc 58 and the terminal head 60 are fixed one to another, for example by plastic deformation and/or by soldering and/or by welding. For example, the terminal head is a rivet head riveted to a fixing hole 62 in the terminal disc and the riveted terminal head is welded to the terminal disc.
The terminal base 52 comprises a base disc 64. The fuse 54 is a portion having a material, a cross section and a thickness such that it melts under the determined specification. For example, the fuse 54 may be made of aluminum. The fuse 54 may be an annular disc with an external diameter of 2,0 to 2,5mm and an inner diameter of 1 ,0mm to 1 ,5mm and having a thickness of 0,1 mm to 0,3mm. The actual dimensions are however determined by the necessary sensitivity of the fuse and can be determined by the person skilled in the art without difficulty. Alternatively, the fuse is a cylindrical portion.
The terminal base 52, respectively the base disc 64, the fuse 54 and the terminal head 60 are advantageously made in one piece, for example by casting and/or laser cutting.
Thus the fuse 54 and the terminal base 52 are made from one piece.
Alternatively, the fuse 54 and the terminal base 52 are two distinct pieces.
The positive terminal assembly 40 further comprises the retaining element 56 holding the terminal plate 50 with respect to the terminal base 52 in absence of the mechanical connection of the terminal plate and the terminal base when the fuse 54 is or has been melted.
The terminal plate 50 and the terminal base 52 comprise each a retaining cavity 68, respectively 70 (see Figure 5). The retaining cavity is in the present case a circular groove defined by the terminal plate 50 and by the terminal base 52. Each retaining cavity defines an undercut in the direction perpendicular to the direction of separation of the terminal plate 50 and the terminal base 52, i.e. perpendicular to the cover plane CP.
In the present embodiment, the retaining element 56 comprises retaining members 72, 74, presently two annular rims, cooperating by complementary of shape (in German: “formschlussig”) with the corresponding retaining cavity 68, 70. The annular rims project radially inwardly.
Alternatively, the retaining members and retaining cavities that cooperate by complementarity of shape may have other shapes, such as pins and holes or indented shapes having matching negative/positive profiles or any other projections and recesses.
In the present case, the retaining element 56 comprises a central disc engaging in a groove that separates the terminal head and the terminal base 52. The retaining members 72, 74 are arranged axially spaced from the central disc on an annular cylinder arranged on the outside of the central disc.
The retaining element 56 is advantageously made from plastic, for example from PPS (Polyphenylene Sulfide), PP (Polypropylene), PBT (Polybutylene Terephthalate), and PFA (Perfluoroalkoxy). Further, the positive terminal assembly 40 together with the cover plate 36 is a module that can be handled separately from the electrochemical cell case 32 or separately from the positive current collector 26.
The positive terminal assembly 40 comprises a fuse cavity 80 adapted to receive the molten fuse material. The fuse cavity 80 is a cavity arranged in the terminal base 52 adjacent to the fuse 54. The fuse cavity 80 has advantageously a size and shape adapted to receive enough molten fuse material so as to avoid accidental reconnection of the terminal base and the terminal plate even after the fuse 54 has been triggered. Such an accidental reconnection could happen in the known terminal assemblies for example by insufficient drain of the molten fuse material.
In particular, the fuse cavity 80 has a volume at least identical to the volume of the fuse 54.
Advantageously, the fuse cavity 80 is open to a side opposite the terminal plate 50, as the molten fuse material may be drained from the terminal assembly. Alternatively, the fuse cavity 80 is closed and adapted to contain the molten fuse material.
Further, the fuse cavity 80 is arranged below the fuse 54, in an operational position of the battery. Generally, the terminal plate 50 is arranged above the terminal base 52 during operation of the battery.
The cover assembly 34 comprises furthermore a gasket 82 arranged between the cover plate 36 and the terminal base 52 and sealing the inside of the case 32 with respect to the outside of the case 32 at the location of the retaining element 56.
The cover plate 36 comprises in the present case two superposed partial cover plates 84, 86 that are assembled together (see Figure 4). A conduction sheet 88 is interposed between the terminal plate 50 and the cover plate 36.
The negative terminal assembly 42 has a structure that is similar to the positive terminal assembly 40, with the following differences, that are depicted on Figure 4.
The negative terminal assembly includes a negative terminal plate 90, a base plate 92, a retainer plate 96, and a gasket 98.
The negative terminal assembly 42 includes elements of the trigger device 38, in particular a pressure membrane 99 (Figure 4).
In the present embodiment, the negative terminal assembly does not comprise a fuse 54 as the positive terminal assembly. Flowever, alternatively the negative terminal assembly incorporates a fuse identical to the fuse of the positive terminal assembly disclosed above. In this case, the corresponding functional elements of the positive terminal assembly such as the terminal plate, base plate, fuse cavity and retaining element and their structural relations, are adapted to the shape and function of the negative terminal assembly.
Alternatively, only the negative terminal assembly comprises a fuse but not the positive terminal assembly.
Figure 6 shows a variant of the positive terminal assembly 40 of the embodiment of figures 1 to 5. This variant differs only in the following features, same or similar features bearing identical reference numbers. Any of the following features may be applied to the foregoing embodiment individually and is not necessarily linked to the remaining features of the variant, but may provide particular advantages in combination.
The fuse 54 is not an annular disc, but a cylindrical portion having a determined cross section. The cylindrical portion may have a cross section comprised between 0.7 mm2 and 2 mm2 and a length comprised between 0.3 mm and 2 mm. These values are at least applicable to an NMC/Graphite element of 40 to 50Ah. The cylindrical portion may be made from aluminum or copper.
The retaining element 56 is attached to the terminal base 52 by corresponding cylindrical surfaces having an interference fit, i.e. by friction only (in German: “reibschlCissig”), instead of complementary of shape. Further, the retaining element 56 is attached to the terminal plate 50 respectively the terminal head 60 by corresponding cylindrical surfaces having an interference fit, i.e. by friction only (in German: “reibschlCissig”), instead of complementary of shape.
Thus, when the fuse 54 is molten and the terminal base 52 is not anymore attached to the terminal head 60 respectively the terminal plate 50 via the fuse 54, the terminal base 52 remains attached to the terminal head 60 and the terminal plate via the retaining element 56.
Of course, one of the attachments of the terminal base 52 to the retaining element 56 and the terminal plate 50 or the terminal head 60 to the retaining element may be an interference fit as in Figure 6 and the other of these attachments may be by complementary of shape as in Figure 5.
The terminal base 52 has a fuse cavity 80 similar to the one of the variant of Figure 5.
Further, the retaining element 56 is arranged at a distance of the fuse 54 and these two elements enclose an annular space that is void. The annular space supports preventing reconnection after melting of the fuse. It also helps the fuse melt down and be mixed with portions of the retaining element 56, thus preventing reconnection. The annular space may have other shapes. The retaining element 56 comprises to this end a dilution portion that is adjacent to the fuse and is able to be molten by the molten fuse material and is able to mix with this molten fuse material.
Figure 7 is a schematic view in cross section of a portion of a cover assembly according to an embodiment of the invention. The view corresponds essentially to the view of Figure 5. This embodiment differs only in the following features from the embodiment of Figures 1 to 5, same or similar features comprising bearing reference numbers. Any of the following features may be applied to the foregoing embodiment individually and is not necessarily linked to the remaining features of the variant, but may provide particular advantages with in combination.
The terminal plate 50, respectively the terminal disc 58, and the terminal base 52, respectively the base disc 64, are fastened one to another by a screw 100. The screw 100 comprises a screw head 60 engaging with the terminal disc 58.
The screw 100 comprises a screw shaft 102 having a threaded screw portion 104. The screw shaft 102 is screwed into a threaded cavity 106 of the base disc 64.
The screw 100 comprises the fuse 54, which extends between the screw head 60 and the screw shaft 102. The fuse 54 is a fuse portion 108 of the screw shaft 102 having a determined electrical resistance. The fuse portion 108 may thus have the electrical features of the fuses 54 disclosed with respect to the remaining embodiments.
The screw 100 may be a screw according to an industry standard, such as a DIN ISO screw or such as a screw CFIC DIN 912 or DIN EN ISO 4762.
The terminal disc 58 may be made from aluminum.
The base disc 64 may be made from aluminum, in particular in case the terminal is a negative terminal, or from copper, in particular in case the terminal is a positive terminal.
The screw 100, or at least a part of the screw, in particular the head 60, may be made from aluminum.
Generally, every combination of aluminum and copper of the above terminal disc 58, base disc 64 and screw 100 is possible. Flowever, the base disc 64 of positive terminal should be aluminum and the base disc 64 of negative terminal should be copper due to electrochemical compatibility inside a cell. Both of positive and negative terminal discs 58 are good to be aluminum for module assembly. If the base disc 64 is copper and the terminal disc 58 is aluminum in a negative terminal, welding these two elements is expensive due to the copper/aluminum junction. The present embodiment comprising a screw 100 does not need a weld of copper/aluminum and comprises a copper base disc 64, aluminum terminal disc 58 and aluminum screw 100 which is an economic combination. The terminal 50 comprises also a diluting insert 110 surrounding the fuse portion 108. The diluting insert 110 is adjacent to the fuse portion 108 and may be made from a non-conductive material that has a melting temperature inferior to the melting temperature of the fuse portion 108. The fuse portion is a recessed portion of the screw shaft, in particular is an annular groove.
Alternatively, the diluting insert 110 is made from a conductive plastic having an electric conductivity lower than the electric conductivity of the fuse in the non-melted state, but an electric conductivity resulting in an electric resistance higher than that of the electric resistance of the fuse, ideally more than 10000 times higher.
The diluting insert 110 is for example made from PPS (Polyphenylene Sulfide), which has the advantage of being compatible with electrolyte, even though it might not necessarily contact the electrolyte. Any electrolyte compatible plastics can be used, such as PP (Polypropylene), PBT (Polybutylene Terephthalate), and PFA (Perfluoroalkoxy).
In case a conductive plastic, is used for the diluting insert 110, when the fuse is activated there will remain an electrical path via the diluting insert 110 between the negative electrode and the positive electrode, but with a very high electric resistance (>100 Ohms). When the membrane is activated and once the fuse is melted, the cell put in a very slow short-circuit via the diluting insert 110, so the electrochemical cell is discharging slowly itself removing the remaining energy from the electrodes.
When the fuse portion 108 melts, the diluting insert 110 is also at least partially melted and mixes with the melted fuse metal. The resulting metal/non-conductive material mix is electrically non-conductive and avoids a reconnection of the terminal plate and the terminal base 52. To prevent reconnection again, a void exists between the fuse 108 and the diluting insert 110, enhancing the mixture of molten fuse and molten diluting insert.
The use of a screw 100 for attaching the elements of the terminal assembly together is advantageous, as no welding or brazing of potentially incompatible materials is necessary. Also, the screw 100 is an economic item. Alternatively, the screw may be replaced by another element, for example a clip having a fuse portion. Generally, the fuse 54 and the terminal base 52 may be two distinct pieces.
The variant of Figure 8 shows also a fuse portion 108 that is a recessed portion of the screw shaft, in particular is an annular groove.
Some of the elements have a different shape than those of figure 7, but the principle of operation is similar.
The above stated fuse 54 and trigger device 38 are integrated in each of the electrochemical cells 4.
The battery or the system 2 work in the following manner. When a thermal incident in a defect electrochemical cells 4 starts, the pressure inside the electrochemical cell 4 increases and triggers the trigger device 38, thus short circuiting the electrodes of the defected electrochemical cell 4 via the fuse 54. Thus the fuse 54 of the defected electrochemical cell 4 melts and the electrodes of the defected electrochemical cell 4 is disconnected from the remainder of the electrochemical cells 4.
Due to the fact that the electrochemical cells 4 are connected one to another in parallel, during the short-circuit of the defected electrochemical cell 4, the remaining electrochemical cells 4 are short-circuited via the trigger device 38 of the defected electrochemical cell 4. This leads to an activation of the fuses of the remaining electrochemical cells 4, which disconnect in turn the electrodes of all the remaining electrochemical cells 4 from the circuit.
The fuses of the remainder of the electrochemical cells are thus also blown, thus totally incapacitating the battery or system 2 and putting it into a safe condition.

Claims

REVENDICATIONS
1 . Cover assembly for a secondary electrochemical cell, comprising
- a cover plate (36),
- a negative terminal (16),
- a positive terminal (18), at least one of the negative terminal or the positive terminal comprising a terminal assembly (40), the terminal assembly (40) comprising:
- a terminal plate (50) adapted to be brought in contact with a connector;
- a terminal base (52) adapted to be electrically connected to a collector of the electrochemical cell;
- a fuse (54) adapted to melt when subject to a determined rated electrical current and/or a determined rated electrical voltage, characterized in that the fuse provides in the unmelted state an electrical connection of the terminal plate with the terminal base, in that the fuse (54) is adapted to, when melting, electrically separate the terminal plate from the terminal base and, upon melting, becoming molten fuse material, wherein the terminal assembly comprises a fuse cavity (80) adapted to receive the molten fuse material.
2. Cover assembly according to claim 1 , wherein the cover assembly comprises a trigger device (38) adapted to trigger the fuse when a predetermined temperature and/or a predetermined pressure is reached, in particular the trigger device being adapted to short circuit a negative and a positive electrode of the electrochemical cell via the fuse.
3. Cover assembly according to any one of claims 1 or 2, wherein the fuse cavity comprises one or more of the following features:
- the fuse cavity (80) is arranged in the terminal base,
- the fuse cavity (80) is open to a side opposite the terminal plate,
- the fuse cavity (80) has a volume at least identical to a volume of the fuse,
- the fuse cavity (80) is arranged below the fuse.
4. Cover assembly according to any one of the preceding claims, wherein either the fuse (54) and the terminal base (52) are one piece or the fuse (54) and the terminal base (52) are two distinct pieces.
5. Cover assembly according to any one of the preceding claims, wherein
- the fuse (54) provides in the unmelted state a mechanical connection of the terminal plate and the terminal base,
- the fuse (54) is adapted to, when melting, mechanically separate the terminal plate from the terminal base and
- the terminal assembly (40) comprises a retaining element (56) holding the terminal plate with respect to the terminal base in absence of the mechanical connection of the terminal plate and the terminal base when the fuse is melted.
6. Cover assembly according to claim 5, wherein the retaining element comprises retaining members (72, 74) cooperating by complementarity of shape with at least one retaining cavity (68, 70) provided in the terminal plate and/or in the terminal base.
7. Cover assembly according to claim 6, wherein the retaining members comprise projections (72, 74) and the retaining cavity comprises at least one recess.
8. Cover assembly according to any one of claims 1 to 7, wherein the retaining element (56) is made from plastic, in particular from PPS (Polyphenylene Sulfide), PP (Polypropylene), PBT (Polybutylene Terephthalate) and PFA (Perfluoroalkoxy).
9. Cover assembly according to any one of the claims 1 to 8, wherein the terminal assembly (40) comprises a screw (100) including a screw shaft (102), in particular a screw according to an industry standard such as a DIN ISO screw, wherein the terminal plate (50) and the terminal base (52) are fastened one to another by the screw, in particular the screw shaft comprising a screw portion (104) and the terminal base comprising a threaded cavity (106) into which the screw portion is screwed, wherein the fuse (54) is a fuse portion (108) of the screw, in particular a portion of the screw shaft (102).
10. Cover assembly according to claim 9, wherein the fuse portion (108) is a recessed portion of the screw shaft (102) and/or the fuse cavity (80) is delimited by the recessed portion of the screw shaft.
11. Electrochemical cell, in particular secondary cell, notably a Lithium-Ion electrochemical cell, comprising - a case (32),
- a cover assembly (34) closing the case,
- a positive electrode (12),
- a negative electrode (10), - a separator (14) interposed between the positive electrode and the negative electrode, wherein the cover assembly (34) is a cover assembly according to any one of the preceding claims.
12. Battery, comprising two, or more than two, electrochemical cells (4) according to claim 11 , the cover assembly of each of the electrochemical cells being a cover assembly of at least claim 2 and the trigger device (38) being adapted to short circuit the negative and the positive electrode of the associated electrochemical cell via the fuse, the positive electrodes of each of the electrochemical cells being electrically connected together and the negative electrodes of each of the electrochemical cells being electrically connected together, the electrochemical cells thus being connected in parallel so that the battery is adapted to short circuit the positive electrode and the negative electrode of each of the electrochemical cells through the trigger device (38) upon triggering of the trigger device.
EP21758747.6A 2021-05-19 2021-05-19 Cover assembly for an electrochemical cell, corresponding electrochemical cell and battery Pending EP4342016A1 (en)

Applications Claiming Priority (1)

Application Number Priority Date Filing Date Title
PCT/IB2021/000479 WO2022243716A1 (en) 2021-05-19 2021-05-19 Cover assembly for an electrochemical cell, corresponding electrochemical cell and battery

Publications (1)

Publication Number Publication Date
EP4342016A1 true EP4342016A1 (en) 2024-03-27

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Family Applications (1)

Application Number Title Priority Date Filing Date
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EP (1) EP4342016A1 (en)
WO (1) WO2022243716A1 (en)

Family Cites Families (6)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
FR2743452A1 (en) 1996-01-08 1997-07-11 Accumulateurs Fixes Safety device for electrochemical generator
EP2399669A1 (en) 2010-06-24 2011-12-28 Borealis Agrolinz Melamine GmbH Horizontal high-pressure melamine reactor
KR101666257B1 (en) * 2013-01-16 2016-10-13 삼성에스디아이 주식회사 Rechargeable battery for supressing arc occurance
KR101696010B1 (en) 2013-06-19 2017-01-12 삼성에스디아이 주식회사 Rechargeable battery
US9741997B2 (en) * 2014-11-05 2017-08-22 Samsung Sdi Co., Ltd. Rechargeable battery
US20220302558A1 (en) * 2019-09-26 2022-09-22 Sanyo Electric Co., Ltd. Secondary battery

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