WO2011058979A1 - Batterie secondaire au lithium - Google Patents

Batterie secondaire au lithium Download PDF

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Publication number
WO2011058979A1
WO2011058979A1 PCT/JP2010/069958 JP2010069958W WO2011058979A1 WO 2011058979 A1 WO2011058979 A1 WO 2011058979A1 JP 2010069958 W JP2010069958 W JP 2010069958W WO 2011058979 A1 WO2011058979 A1 WO 2011058979A1
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WIPO (PCT)
Prior art keywords
positive electrode
electrode layer
negative electrode
secondary battery
lithium secondary
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PCT/JP2010/069958
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English (en)
Japanese (ja)
Inventor
宏基 粟野
英行 森本
真一 鳶島
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トヨタ自動車株式会社
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Publication of WO2011058979A1 publication Critical patent/WO2011058979A1/fr

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    • 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
    • H01M4/62—Selection of inactive substances as ingredients for active masses, e.g. binders, fillers
    • 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
    • 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 relates to a lithium secondary battery, and more particularly to a lithium secondary battery including a heat absorbing material that suppresses battery temperature rise when the battery is misused such as internal short circuit or overcharge.
  • a lithium secondary battery (for example, a lithium ion battery) that is charged and discharged by moving lithium ions back and forth between the positive electrode and the negative electrode is lightweight and has a high energy density. The importance is increasing as what is preferably used for the power supply of a portable terminal.
  • the battery When charging a lithium secondary battery, if the battery is overcharged due to malfunction due to the presence of a defective battery or a failure of the charger, the battery may be overcharged, or an internal short circuit may cause It is assumed that a short-circuit current flows in In the case of such overcharge, the battery reaction rapidly proceeds, gas is generated inside the battery case, the internal pressure inside the case rises, and the electrolytic solution decomposes on the surface of the active material or the electrode The temperature inside the battery may rise due to the heat generated in the active material. At this time, if the battery is provided with a safety valve or the like, the gas is discharged to the outside by the operation of the safety valve or the like, thereby preventing problems such as deformation of the case and interrupting the current.
  • Patent Document 1 describes a technique for suppressing an increase in temperature in a battery in an emergency by adding an endothermic substance accompanying a phase change in a positive electrode layer.
  • Patent Document 2 discloses that a battery in which a material accompanied with a phase change is placed in an inert material capsule is added to an electrode active material to effectively suppress a temperature increase during normal and abnormal battery operation. The technology which tries to improve the life and safety of is described.
  • the present invention has been created to solve the above-described conventional problems, and its purpose is to prevent the occurrence of problems due to thermal decomposition of the positive electrode active material in the event of battery abnormality. It is to provide a battery.
  • a lithium secondary battery including an electrode body including a positive electrode and a negative electrode, and a case for housing the electrode body and an electrolyte.
  • the positive electrode includes a positive electrode layer mainly composed of a positive electrode active material formed on a positive electrode current collector, and the negative electrode is formed on the negative electrode current collector.
  • a negative electrode layer mainly composed of the negative electrode active material.
  • At least one of the positive electrode layer and the negative electrode layer (hereinafter, the positive electrode layer and the negative electrode layer are collectively referred to as an electrode layer) is a substance that exhibits a phase change (phase transition) from solid to liquid at a predetermined temperature. Contains an endothermic material.
  • the endothermic material has a double structure in which the surface is covered with an oxide film made of an oxide of the substance constituting the endothermic material, and the temperature of the electrode layer including the endothermic material reaches the predetermined temperature.
  • the endothermic material is configured to change phase from solid to liquid and to flow out to the inner region of the electrode layer.
  • the “lithium secondary battery” refers to a secondary battery that uses lithium ions as electrolyte ions and is charged and discharged by movement of lithium ions between the positive and negative electrodes.
  • a secondary battery generally referred to as a lithium ion battery is a typical example included in the lithium secondary battery in this specification.
  • the “positive electrode active material” means a positive electrode side capable of reversibly occluding and releasing (typically inserting and removing) chemical species (here, lithium ions) which are charge carriers in a secondary battery. The active material.
  • the “negative electrode active material” refers to a negative electrode capable of reversibly occluding and releasing (typically inserting and removing) chemical species (here, lithium ions) that serve as charge carriers in a secondary battery.
  • chemical species here, lithium ions
  • the lithium secondary battery provided by the present invention includes an endothermic material made of a substance that exhibits a phase change from solid to liquid at a predetermined temperature in at least one of the positive electrode layer and the negative electrode layer,
  • the surface of the endothermic material has a double structure (typically a structure composed of a metal material and an oxide film of the metal material) coated with an oxide film composed of an oxide of the material constituting the endothermic material.
  • the endothermic material changes phase from solid to liquid and flows out to the inner region of the electrode layer.
  • the endothermic material contained in the electrode layer has a double structure covered with an oxide film made of an oxide of the endothermic material.
  • the charge / discharge potential region during typical use of a lithium secondary battery (typically Specifically, it is possible to prevent the endothermic material from being dissolved and dissolved out as ions at 3.0 V to 4.1 V).
  • a predetermined temperature melting point of the endothermic material
  • the endothermic material absorbs heat from decomposition of the active material and the electrolytic solution and becomes liquid from solid Therefore, a further temperature increase of the electrode layer can be suppressed.
  • the endothermic material contained in the electrode layer undergoes a phase change from solid to liquid, and the liquefied (molten) endothermic material flows out into the inner region of the electrode layer, thereby causing the endothermic material in the molten (liquid) state.
  • the material covers the surface of the active material. Accordingly, since the surface area of the active material is reduced, the decomposition reaction of the electrolytic solution on the active material surface is stopped or reduced, and heat generation due to the decomposition reaction is suppressed. Furthermore, since the release and / or occlusion of lithium ions from the surface of the active material is blocked and the flow of current is shut down, heat generation in the active material can be suppressed (the exothermic reaction in the active material is thereby converged). To go). Therefore, according to the present invention, it is possible to provide a lithium secondary battery that is excellent in safety and reliability without causing trouble in the battery due to a rapid thermal decomposition reaction of the active material in the event of battery abnormality.
  • the endothermic material is configured by a material that melts at a temperature lower than a temperature at which the positive electrode active material undergoes a thermal decomposition reaction.
  • the endothermic material is made of a metal material, particularly tin or a solder alloy containing tin as a main component.
  • the melting point of tin or a solder alloy containing tin as a main component is relatively low, and is about the same as or lower than the temperature at which the active material contained in the electrode layer causes a thermal decomposition reaction. Therefore, even when the battery is abnormal such as overcharge, the temperature rise of the electrode layer can be suppressed by the phase change of the endothermic material before the thermal decomposition reaction of the active material occurs, or the thermal decomposition reaction of the active material has occurred. However, the temperature increase of the electrode layer can be suppressed immediately by the phase change of the endothermic material. Further, since the liquefied (molten) endothermic material covers the surface of the active material, the battery reaction is shut down, so that it is possible to prevent the battery from being defective.
  • the endothermic material is included in at least the positive electrode layer.
  • the positive electrode active material has a lower temperature at which the thermal decomposition reaction of the active material itself occurs than the negative electrode active material. Therefore, the thermal decomposition reaction of the positive electrode active material in the positive electrode layer that can occur in a lower temperature region than the negative electrode layer can be more effectively prevented by including the endothermic material having the double structure in the positive electrode layer.
  • a vehicle including any of the lithium secondary batteries disclosed herein (typically lithium ion batteries).
  • the lithium secondary battery provided by the present invention may exhibit quality suitable as a lithium secondary battery mounted on a vehicle (for example, further improvement in safety and reliability of the lithium secondary battery). Therefore, the lithium secondary battery can be suitably used as a power source for a motor (electric motor) mounted on a vehicle such as an automobile equipped with an electric motor such as a hybrid vehicle, an electric vehicle, and a fuel cell vehicle.
  • a motor electric motor mounted on a vehicle such as an automobile equipped with an electric motor such as a hybrid vehicle, an electric vehicle, and a fuel cell vehicle.
  • FIG. 1 is a perspective view schematically showing the outer shape of a lithium secondary battery according to an embodiment.
  • FIG. 2 is a longitudinal sectional view taken along line II-II in FIG.
  • FIG. 3 is a schematic diagram illustrating a positive electrode layer formed on a positive electrode current collector according to an embodiment.
  • FIG. 4 is a schematic diagram illustrating a negative electrode layer formed on a negative electrode current collector according to an embodiment.
  • FIG. 5 is a graph showing the relationship between SOC and battery temperature.
  • FIG. 6 is a side view schematically showing a vehicle (automobile) provided with the lithium secondary battery according to the present invention.
  • the positive electrode provided in the lithium secondary battery disclosed herein can have the same configuration as the conventional one except that it includes a heat-absorbing material characterized by the present invention.
  • a positive electrode current collector constituting such a positive electrode a conductive material made of a metal having good conductivity is used as in the current collector used for a positive electrode of a conventional lithium secondary battery (typically, a lithium ion battery).
  • a member is preferably used.
  • aluminum or an alloy containing aluminum as a main component can be used.
  • the shape of the positive electrode current collector can vary depending on the shape of the lithium secondary battery, and is not particularly limited, and may be various forms such as a rod shape, a plate shape, a sheet shape, a foil shape, and a mesh shape. Typically, a sheet-like positive electrode current collector made of aluminum is used.
  • a composition in which a positive electrode active material, a conductive material, a binder (binder), an endothermic material, etc. are mixed in an appropriate solvent typically a composition formed in a paste form
  • Product hereinafter referred to as a positive electrode layer forming paste
  • a granular active material capable of inserting and extracting lithium is used as the positive electrode active material included in the positive electrode layer formed on the positive electrode of the lithium secondary battery disclosed herein.
  • a typical positive electrode active material includes a composite oxide containing lithium and at least one transition metal element.
  • cobalt lithium composite oxide (LiCoO 2 ), nickel lithium composite oxide (LiNiO 2 ), manganese lithium composite oxide (LiMn 2 O 4 ), or nickel / cobalt-based LiNi x Co 1-x O 2 ( 0 ⁇ x ⁇ 1), cobalt / manganese-based LiCo x Mn 1-x O 2 (0 ⁇ x ⁇ 1), nickel / manganese-based LiNi x Mn 1-x O 2 (0 ⁇ x ⁇ 1) and LiNi x Mn 2-x O 4 (0 ⁇ x ⁇ 2), so-called binary lithium-containing composite oxide containing two kinds of transition metal elements, or nickel, cobalt, containing three kinds of transition metal elements
  • a ternary lithium-containing composite oxide such as manganese may be used.
  • an olivine type lithium phosphate represented by the general formula LiMPO 4 (M is at least one element of Co, Ni, Mn, Fe; for example, LiFePO 4 , LiMnPO 4 ) is preferably used as the positive electrode active material. It is done.
  • the positive electrode active material has a general formula of LiMAO 4 (where M is at least one metal element selected from the group consisting of Fe, Co, Ni and Mn, and A is P, Si, S and It is also possible to use a polyanionic compound represented by the above-mentioned element selected from the group consisting of V.
  • a compound constituting such a positive electrode active material can be prepared and provided by, for example, a conventionally known method.
  • the oxide can be prepared by mixing several raw material compounds appropriately selected according to the atomic composition at a predetermined molar ratio and firing the mixture at a predetermined temperature by an appropriate means. Further, the fired product is pulverized, granulated and classified by an appropriate means to obtain a granular positive electrode active material powder substantially composed of secondary particles having a desired average particle size and / or particle size distribution. be able to.
  • the preparation method itself of a positive electrode active material does not characterize this invention at all.
  • the conductive material contained in the positive electrode layer formed on the positive electrode disclosed herein is not limited to a specific conductive material as long as it is conventionally used in this type of secondary battery.
  • carbon materials such as carbon powder and carbon fiber can be used.
  • carbon powder various carbon blacks (for example, acetylene black, furnace black, ketjen black), graphite powder, and the like can be used. You may use 1 type or 2 types or more together among these.
  • the endothermic material contained in the positive electrode layer formed in the positive electrode disclosed herein a substance that changes in phase from a solid to a liquid at a predetermined temperature, for example, a relatively low melting point (for example, a melting point of 250 ° C. or lower, preferably 200 ° C. to 250 ° C. or 200 ° C. or less) and various alloy materials containing the metal as a main component.
  • a relatively low melting point for example, a melting point of 250 ° C. or lower, preferably 200 ° C. to 250 ° C. or 200 ° C. or less
  • various alloy materials containing the metal as a main component for example, a relatively low melting point (for example, a melting point of 250 ° C. or lower, preferably 200 ° C. to 250 ° C. or 200 ° C. or less) and various alloy materials containing the metal as a main component.
  • the metal material having a melting point of 250 ° C. or lower or 200 ° C. or lower include a sold
  • solder alloy lead-free solder (lead-free solder) is preferable in consideration of the influence on the natural environment and the human body.
  • the solder material is preferably a material having a melting point lower than the temperature at which the thermal decomposition reaction of the positive electrode active material proceeds (thermal decomposition temperature, typically a temperature range of about 200 ° C. to 300 ° C.).
  • thermal decomposition temperature typically a temperature range of about 200 ° C. to 300 ° C.
  • solder materials Sn (melting point: 232 ° C.), Sn—Cu type (melting point: 227 ° C.), Sn—Ag type (melting point: 221 ° C.), Sn—Ag—Cu type (melting point: 217 ° C.
  • the amount of the endothermic material (typically a solder material) is appropriately determined, but it is preferably used in an amount that does not hinder the conductivity of the positive electrode layer, that is, about 1 to 30 parts by mass with respect to 100 parts by mass of the positive electrode active material. More preferably, it is about 5 to 15 parts by mass.
  • the average particle diameter based on observation of an endothermic material (solder material) by an electron microscope (such as SEM or TEM) (or based on a light scattering method) is preferably in the range of 0.1 ⁇ m to 100 ⁇ m, and more preferably Is in the range of 1 ⁇ m to 10 ⁇ m.
  • the endothermic material when the endothermic material is not entirely covered with an oxide film, the endothermic material is configured in the normal charge / discharge potential range (typically 3.0 V to 4.1 V) of the lithium secondary battery.
  • the substance to be dissolved becomes ions and dissolves in the electrolyte.
  • the endothermic material dissolved in the electrolyte as ions cannot absorb the heat in the case (typically the heat of the electrode layer) when the battery is abnormal such as overcharge. There is a risk that the decomposition reaction proceeds and the temperature of the electrode layer rises rapidly, causing a problem in the battery.
  • the endothermic material (typically, solder material) has a double structure (typically endothermic) in which the surface is coated with an oxide film made of an oxide of a substance constituting the endothermic material.
  • the entire material is covered with an oxide film, and the endothermic material component (that is, the inside of the oxide film) and the outside (for example, air, electrolyte, etc.) are not in direct contact with each other. ).
  • the endothermic material does not dissolve in the electrolyte solution in the normal charge / discharge potential region of the lithium secondary battery, and the battery layer can absorb heat when the battery is abnormal, causing problems in the battery. It can be prevented in advance.
  • the endothermic material having the above average particle diameter can be produced by various conventionally known methods.
  • it can be produced by various liquid phase methods such as spray pyrolysis and various gas phase methods such as chemical vapor deposition.
  • a method for forming an oxide film on the surface of the endothermic material for example, a method in which a powder of the endothermic material is heat-treated in an oxygen atmosphere at a temperature lower than the melting point of the endothermic material.
  • the oxide film can also be formed by a technique similar to a conventionally known method such as a sol-gel method or a coating method.
  • binder contained in the positive electrode layer formed in the positive electrode disclosed herein, for example, when an aqueous liquid composition is used as the composition for forming the positive electrode layer, Polymer materials that dissolve or disperse can be preferably employed.
  • Cellulose polymers such as carboxymethylcellulose (CMC), methylcellulose (MC), cellulose acetate phthalate (CAP), hydroxypropylmethylcellulose (HPMC), etc .; polyvinyl alcohol (PVA) And the like are exemplified.
  • polymer materials that are dispersed in water include fluorine resins such as polytetrafluoroethylene (PTFE); vinyl acetate copolymers; rubbers such as styrene butadiene rubber (SBR);
  • PTFE polytetrafluoroethylene
  • SBR styrene butadiene rubber
  • a solvent-based liquid composition typically a composition prepared in the form of a paste or slurry, hereinafter referred to as a positive electrode layer forming paste
  • a polyfluoride is used as the composition for forming the positive electrode layer
  • Polymer materials such as vinylidene chloride (PVDF) and polyvinylidene chloride (PVDC) can be used.
  • PVDF vinylidene chloride
  • PVDC polyvinylidene chloride
  • the polymer material illustrated above may be used as a thickener and other additives in the above composition in addition to being used as a binder.
  • the “aqueous liquid composition” is a concept indicating a composition using water or a mixed solvent mainly composed of water (aqueous solvent) as a dispersion medium of the active material.
  • aqueous solvent aqueous solvent
  • one or more organic solvents lower alcohol, lower ketone, etc.
  • the “solvent-based liquid composition” is a concept indicating a composition in which a dispersion medium of an active material is mainly an organic solvent (non-aqueous solvent).
  • the organic solvent for example, N-methylpyrrolidone (NMP) can be used.
  • the positive electrode disclosed here can be suitably manufactured, for example, generally by the following procedure.
  • a positive electrode layer forming paste is prepared by dispersing the above-described positive electrode active material, conductive material, endothermic material, binder material soluble in an organic solvent, and the like in an organic solvent.
  • the prepared paste is applied to a positive electrode current collector, dried, and then compressed (pressed) to produce a positive electrode including the positive electrode current collector and a positive electrode layer formed on the positive electrode current collector.
  • manganese lithium composite oxide (positive electrode layer using LiMn 2 O 4 as a positive electrode active material) is relatively excellent in thermal stability, and its thermal decomposition temperature is typically about 300 ° C. to 330 ° C. .
  • the thermal decomposition temperature of the cobalt lithium composite oxide is typically about 240 ° C. to 270 ° C.
  • the thermal decomposition temperature of the nickel lithium composite oxide is typically about 210 ° C. to 230 ° C.
  • the negative electrode disclosed here is a negative electrode for a lithium secondary battery including a negative electrode current collector and a negative electrode layer formed on the current collector.
  • the negative electrode current collector constituting such a negative electrode for example, copper, nickel, or an alloy containing them as a main component can be used.
  • the negative electrode active material contained in the negative electrode layer formed in the negative electrode disclosed herein may be any material that can occlude and release lithium.
  • carbon materials such as graphite, lithium / titanium
  • oxide materials such as oxide (Li 4 Ti 5 O 12 ), alloy materials composed of alloys such as tin, aluminum (Al), zinc (Zn), and silicon (Si).
  • a typical example is the amount of powdery carbon material made of graphite or the like.
  • the graphite particles can be a negative electrode active material more suitable for rapid charge / discharge (for example, high-power discharge) because the particle size is small and the surface area per unit volume is large.
  • the negative electrode layer formed in the negative electrode disclosed herein may contain one or more materials that can be blended in the positive electrode layer, if necessary, in addition to the negative electrode active material.
  • various materials that can function as binders and heat absorbing materials as listed as constituent materials of the positive electrode layer can be used in the same manner.
  • the amount of the endothermic material (typically a solder material) is preferably about 1 to 40 parts by mass with respect to 100 parts by mass of the negative electrode active material. More preferably, it is about 5 to 20 parts by mass.
  • the negative electrode disclosed here can be manufactured by the same method as that for the positive electrode.
  • a paste-like (or slurry-like) composition (hereinafter referred to as a negative electrode layer forming paste) is prepared by dispersing a negative electrode active material, an endothermic material, a binder and the like in an appropriate solvent.
  • the prepared paste for forming a negative electrode layer is applied to a negative electrode current collector, dried, and then compressed (pressed) to provide a negative electrode current collector and a negative electrode layer formed on the negative electrode current collector.
  • a negative electrode can be produced.
  • separator used with a positive electrode and a negative electrode
  • the separator similar to the past can be used.
  • a porous sheet (porous film) made of a polyolefin resin can be used.
  • a polymer solid electrolyte can be used as a separator.
  • the same electrolyte as a non-aqueous electrolyte (typically, an electrolytic solution) conventionally used for a lithium secondary battery can be used without particular limitation.
  • a nonaqueous electrolyte typically has a composition in which a supporting salt is contained in a suitable nonaqueous solvent.
  • the non-aqueous solvent include one or two selected from the group consisting of ethylene carbonate (EC), ethyl methyl carbonate (EMC), dimethyl carbonate (DMC), diethyl carbonate (DEC), propylene carbonate (PC), and the like. More than seeds can be used.
  • the supporting salt for example, can be used LiPF 6, LiBF 4, LiAsF 6 , LiCF 3 SO 3 , etc.
  • the shape (outer shape and size) of the lithium secondary battery to be constructed is not particularly limited.
  • the outer package may be a thin sheet type constituted by a laminate film or the like, and the battery outer case may be a cylindrical or cuboid battery, or may be a small button shape.
  • FIG. 1 is a perspective view schematically showing a lithium secondary battery according to an embodiment.
  • FIG. 2 is a longitudinal sectional view taken along line II-II in FIG.
  • the lithium secondary battery 10 according to the present embodiment includes the above-described lithium secondary battery constituent materials (active material for each positive and negative electrode, current collector for each positive and negative electrode, separator, etc.).
  • An electrode body 50 is provided, and a flat rectangular parallelepiped (that is, rectangular) battery case 15 that accommodates the electrode body 50 and a suitable nonaqueous electrolyte (electrolyte).
  • the case 15 is attached to (for example, welded) the box-shaped case main body 30 in which one of the narrow surfaces of the flat rectangular parallelepiped shape is the opening 20 and the opening 20 is closed. And a lid 25.
  • a material constituting the case 15 the same material as that used in a general lithium secondary battery can be used as appropriate, and there is no particular limitation.
  • a container made of metal for example, aluminum or steel
  • a container made of synthetic resin for example, polyolefin-based resin
  • the case 15 according to the present embodiment is made of, for example, aluminum.
  • the lid body 25 is formed in a rectangular shape that matches the shape of the opening 20 of the case body 30.
  • the lid body 25 is provided with a positive electrode terminal 60 and a negative electrode terminal 70 for external connection, respectively, and a part of these terminals 60, 70 protrudes from the lid body 25 toward the outside of the case 15. It is formed to do.
  • the lid 25 is provided with a safety valve (not shown) for discharging the gas generated inside the case 15 to the outside of the case 15 when the battery is abnormal. It has been.
  • the safety valve can be used without any limitation as long as it has a mechanism that opens and discharges gas to the outside of the case 15 when the pressure inside the case 15 exceeds a predetermined level.
  • the lithium secondary battery 10 includes a wound electrode body 50 (hereinafter may be abbreviated as “electrode body 50”) in the same manner as a normal lithium secondary battery.
  • the electrode body 50 is accommodated in the case main body 30 in a posture in which the winding axis is laid down (that is, in the direction in which the opening 20 is positioned in the lateral direction with respect to the winding axis).
  • the electrode body 50 includes a positive electrode sheet (positive electrode) 66 in which a positive electrode layer (electrode layer) 64 is formed on the surface of a long sheet-like positive electrode current collector 62 and a surface of a long sheet-like negative electrode current collector 72.
  • a negative electrode sheet (negative electrode) 76 on which a negative electrode layer (electrode layer) 74 is formed is overlapped with two long sheet-like separators 80 and wound, and the resulting electrode body 50 is crushed from the side surface direction. By doing so, it is formed into a flat shape.
  • the positive electrode current collector 62 is exposed without forming the positive electrode layer 64 at one end portion along the longitudinal direction, while the negative electrode sheet 76 is wound.
  • the negative electrode current collector 72 is exposed at one end along the longitudinal direction without the negative electrode layer 74 being formed.
  • a positive electrode terminal 60 is joined to the exposed end of the positive electrode current collector 62, and is electrically connected to the positive electrode sheet 66 of the wound electrode body 50 formed in the flat shape.
  • the negative electrode terminal 70 is joined to the exposed end portion of the negative electrode current collector 72 and is electrically connected to the negative electrode sheet 76.
  • the positive and negative electrode terminals 60 and 70 and the positive and negative electrode current collectors 62 and 72 can be joined by, for example, ultrasonic welding, resistance welding, or the like.
  • FIG. 3 is a schematic diagram showing the positive electrode layer 64 formed on the positive electrode current collector 62 according to an embodiment.
  • FIG. 4 is a schematic diagram showing the negative electrode layer 74 formed on the negative electrode current collector 72 according to one embodiment.
  • the positive electrode sheet 66 is produced by forming a positive electrode layer 64 on a long positive electrode current collector (for example, a long aluminum foil) 62. That is, a positive electrode active material (for example, LiCoO 2 ) 67, a conductive material (for example, graphite) 68, an endothermic material (for example, tin) 69, and a binder (for example, PVDF) that is soluble in an organic solvent is converted into an organic solvent (for example, NMP).
  • a positive electrode layer forming paste dispersed in is prepared. The prepared paste is applied to the positive electrode current collector 62, dried, and then compressed (pressed) to form the positive electrode layer 64.
  • the paste can be suitably applied to the positive electrode current collector 62 by using an appropriate application device such as a slit coater, a die coater, a gravure coater, or a comma coater.
  • an appropriate application device such as a slit coater, a die coater, a gravure coater, or a comma coater.
  • conventionally known compression methods such as a roll press method and a flat plate press method can be employed. In adjusting the thickness, the thickness may be measured with a film thickness measuring instrument, and the press pressure may be adjusted to compress a plurality of times until a desired thickness is obtained.
  • the negative electrode sheet 76 is produced by forming a negative electrode layer 74 on a long negative electrode current collector (for example, a long copper foil) 72. That is, for forming a negative electrode layer in which a negative electrode active material (for example, graphite) 77, an endothermic material (for example, tin) 79 and a binder (for example, PVDF) that is soluble in an organic solvent are dispersed in an organic solvent (for example, NMP).
  • a negative electrode active material for example, graphite
  • an endothermic material for example, tin
  • a binder for example, PVDF
  • the positive electrode sheet 66 and the negative electrode sheet 76 produced above are stacked and wound together with two separators (for example, porous polyolefin resin) 80, and the wound electrode body 50 obtained is rolled into the case body 30 with its winding shaft lying sideways.
  • a non-aqueous electrolyte such as a mixed solvent of EC and DMC (for example, a mass ratio of 1: 1) containing a suitable supporting salt (for example, a lithium salt such as LiPF 6 ) in an appropriate amount (for example, a concentration of 1 M).
  • the lithium secondary battery 10 of the present embodiment can be constructed by mounting the lid body 25 in the opening 20 and sealing (for example, laser welding).
  • the endothermic material is included in at least one of the positive electrode layer and the negative electrode layer, preferably included in the positive electrode layer, and more preferably included in each of the positive electrode layer and the negative electrode layer.
  • each of the positive electrode layer 64 and the negative electrode layer 74 includes endothermic materials (tin) 69 and 79.
  • the positive electrode active material 67 causes self-heating, or decomposition of the electrolyte progresses on the surfaces of the positive electrode active material 67 and the negative electrode active material 77.
  • the temperature of the positive electrode layer 64 and the negative electrode layer 74 may increase due to heat generation.
  • the endothermic materials contained in the positive electrode layer 64 and the negative electrode layer 74 respectively.
  • the liquefied (melted) endothermic materials 69 and 79 flow into the inner region of the positive electrode layer 64 and the inner region of the negative electrode layer 74 to coat (coat) the surfaces of the positive electrode active material 67 and the negative electrode active material 77, respectively.
  • the active materials 67 and 77 whose surfaces are covered (coated) with the endothermic materials 69 and 79 have zero or small surface area in contact with the electrolytic solution, the decomposition reaction of the electrolytic solution on the surfaces of the active materials 67 and 77 is performed. Is stopped or suppressed, and the calorific value becomes zero or decreases. Further, in the positive electrode active material 67 whose surface is coated with the endothermic material 69, lithium ions are not released from the surface, so that the flow of current can be shut down and the temperature rise of the battery 10 can be suppressed.
  • the positive electrode active material 67 does not reach the temperature at which the thermal decomposition reaction accompanied by oxygen release proceeds, but is caused by the rapid increase of the temperature accompanying the thermal decomposition reaction.
  • production of the malfunction of the lithium secondary battery 10 can be prevented beforehand.
  • the endothermic material for example, Sn
  • the endothermic material has a melting point higher than the temperature at which the thermal decomposition reaction of the positive electrode active material (for example, LiNiO 2 ) proceeds (for example, about several to several tens of degrees Celsius).
  • the endothermic material absorbs the heat of the positive electrode layer and changes from a solid to a liquid, Further temperature increase of the positive electrode layer can be suppressed.
  • the liquefied (molten) endothermic material covers the surface of the positive electrode active material, thereby stopping or reducing the decomposition reaction of the electrolyte solution on the surface of the positive electrode active material and suppressing the thermal decomposition reaction of the positive electrode active material.
  • release of oxygen accompanying decomposition of the positive electrode active material can be prevented. For this reason, the reaction between the evaporated organic solvent in the battery case and oxygen can be suppressed. From the above, the exothermic reaction of the positive electrode layer converges, and it is possible to prevent the occurrence of battery malfunctions accompanying the thermal decomposition reaction.
  • a lithium secondary battery (18650 type cell) was constructed as follows. First, the positive electrode of the lithium secondary battery according to the example was produced. That is, tin powder (average particle size of 10 ⁇ m or less) as an endothermic material is exposed to 200 ° C. below the melting point of tin (232 ° C.) for 3 hours in an oxygen atmosphere to form an oxide film made of tin oxide on the surface of tin. did. Then, it is weighed so that the mass ratio of these materials is 80: 5: 5: 10 including lithium cobaltate as a positive electrode active material, carbon black, PVDF, and tin (surface tin oxide) coated with the above oxide film.
  • tin powder average particle size of 10 ⁇ m or less
  • the mass ratio of these materials is 80: 5: 5: 10 including lithium cobaltate as a positive electrode active material, carbon black, PVDF, and tin (surface tin oxide) coated with the above oxide film.
  • a positive electrode layer forming paste paste (paste-like composition).
  • the paste was applied to both sides of a positive electrode current collector (thickness: 15 ⁇ m) made of aluminum foil so that the applied amount of the paste was 12 mg / cm 2 and dried. After drying, the coating was pressed, the thickness 80 ⁇ m of the positive electrode layer was formed a positive electrode layer of density 2.5 g / cm 3 of the positive electrode layer. Thus, a sheet-like positive electrode (positive electrode sheet) was produced.
  • the negative electrode of the lithium secondary battery according to the example was produced.
  • the graphite powder as the negative electrode active material and PVDF as the binder are weighed so that the mass ratio of these materials becomes 93: 7, and these materials are dispersed in NMP to prepare the negative electrode layer forming paste.
  • the paste was applied to both sides of a negative electrode current collector (thickness: 15 ⁇ m) made of copper foil so that the applied amount of the paste was 8 mg / cm 2 and dried. After drying, the coated material was pressed to form a negative electrode layer having a negative electrode layer thickness of 40 ⁇ m and a negative electrode layer density of 1.4 g / cm 3 . In this way, a sheet-like negative electrode (negative electrode sheet) was produced.
  • the prepared positive electrode sheet and negative electrode sheet are laminated together with two long separators (here, a porous polypropylene sheet is used), and the laminated sheet is wound in the longitudinal direction to form a wound electrode body.
  • the electrode body and the electrolyte were housed in a container equipped with a safety valve to construct a cylindrical lithium secondary battery having a diameter of 18 mm and a height of 65 mm (18650 type).
  • a nonaqueous electrolytic solution having a composition in which 1 mol / L LiPF 6 was dissolved in a 3: 7 (volume ratio) mixed solvent of ethylene carbonate (EC) and dimethyl carbonate (DMC) was used.
  • a lithium secondary battery (18650 type cell) was constructed as follows. First, the positive electrode of the lithium secondary battery which concerns on a comparative example was produced. That is, without using tin (surface tin oxide) coated on the oxide film, the mass ratio of these materials including lithium cobaltate, carbon black, and PVDF as the positive electrode active material is 80: 15: 5. Then, these materials were dispersed in NMP to prepare a positive electrode layer forming paste (paste-like composition). And the positive electrode which concerns on a comparative example was produced in the procedure similar to the said Example. In this comparative example, a lithium secondary battery according to this comparative example was constructed in the same procedure as the example using the negative electrode similar to the example except that the positive electrode prepared above was used.
  • the safety valve provided in the case was opened near SOC 185% (portion surrounded by the dotted line in FIG. 5) in both the example and the comparative example.
  • the temperature was further increased after the safety valve was opened and the malfunction occurred beyond the temperature at which the thermal decomposition reaction of the positive electrode active material proceeds (the temperature indicated by the dotted line in FIG. 5). It was.
  • the temperature of the battery according to the example has risen even after the safety valve is opened, it does not reach the temperature at which the thermal decomposition reaction of the positive electrode active material proceeds, and the occurrence of a malfunction (for example, smoke) It was not confirmed. From the above, it is shown that the lithium secondary battery according to the example is a lithium secondary battery that is excellent in safety and reliability without causing malfunction of the battery even when the battery is abnormal due to overcharge. It was done.
  • the present invention is not limited to the prismatic battery described above, and can be applied to lithium secondary batteries having various shapes (for example, a cylindrical shape).
  • the configuration of the electrode body is not limited to the wound type as described above, and may be, for example, a laminated type electrode body (laminated electrode body) formed by alternately laminating positive and negative electrode sheets together with a separator sheet.
  • the lithium secondary battery according to the present invention (for example, a lithium ion battery) is excellent in safety and reliability because it can prevent the occurrence of problems due to thermal decomposition of the positive electrode active material in the event of battery abnormality. Since a large current output is possible, it can be suitably used as a power source for a motor (electric motor) mounted on a vehicle such as an automobile. Therefore, as schematically shown in FIG. 6, the present invention provides a vehicle (typically, a battery (typically, an assembled battery formed by connecting a plurality of such batteries 10 in series) as a power source. Automobiles, in particular automobiles equipped with electric motors such as hybrid cars, electric cars, fuel cars, etc.) 100.

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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)
  • Secondary Cells (AREA)
  • Battery Electrode And Active Subsutance (AREA)

Abstract

La présente invention concerne une batterie secondaire au lithium, pouvant empêcher l'apparition d'une défaillance due à la décomposition thermique du matériau actif d'électrode positive en cas de dysfonctionnement de la batterie. La batterie secondaire au lithium comprend : un corps d'électrode comprenant une électrode positive (66) et une électrode négative ; et un boîtier logeant le corps d'électrode et un électrolyte. L'électrode positive comprend une couche d'électrode positive (64), formée sur un collecteur d'électrode positive (62), et principalement composée d'un matériau actif d'électrode positive. L'électrode négative comprend une couche d'électrode négative, formée sur un collecteur d'électrode négative, et principalement composée d'un matériau actif d'électrode négative. La couche d'électrode positive et/ou la couche d'électrode négative contiennent un matériau absorbant la chaleur (69), composé d'une substance subissant un changement de phase et passant de l'état solide à liquide à une température spécifique. Le matériau absorbant la chaleur présente une structure double, sa surface étant recouverte d'un film d'oxyde composé d'un oxyde de la substance constituant le matériau absorbant la chaleur, et lorsque la température de la couche d'électrode atteint la température spécifique, le matériau absorbant la chaleur subit un changement de phase de solide à liquide et s'écoule dans la région interne de la couche d'électrode.
PCT/JP2010/069958 2009-11-10 2010-11-09 Batterie secondaire au lithium WO2011058979A1 (fr)

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CN112952103A (zh) * 2021-03-03 2021-06-11 浙江工业大学 一种智能调温集流体的制备方法及应用
CN113517444A (zh) * 2020-04-10 2021-10-19 荣盛盟固利新能源科技有限公司 集流体、集流体制造方法、电极极片及锂离子电池
WO2024098294A1 (fr) * 2022-11-09 2024-05-16 宁德时代新能源科技股份有限公司 Ensemble feuille d'électrode négative et procédé de stockage de feuille d'électrode négative enrichie en lithium

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CN103687675B (zh) * 2011-07-28 2015-11-25 住友化学株式会社 层叠多孔质薄膜的制造方法
CA2881801C (fr) * 2012-08-27 2017-07-18 Nippon Steel & Sumitomo Metal Corporation Materiau de base actif pour electrodes negatives
EP4040522A1 (fr) * 2021-02-03 2022-08-10 Samsung SDI Co., Ltd. Batterie rechargeable entièrement solide

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CN113517444A (zh) * 2020-04-10 2021-10-19 荣盛盟固利新能源科技有限公司 集流体、集流体制造方法、电极极片及锂离子电池
CN113517444B (zh) * 2020-04-10 2023-01-13 荣盛盟固利新能源科技有限公司 集流体、集流体制造方法、电极极片及锂离子电池
CN112952103A (zh) * 2021-03-03 2021-06-11 浙江工业大学 一种智能调温集流体的制备方法及应用
CN112952103B (zh) * 2021-03-03 2023-04-25 浙江工业大学 一种智能调温集流体的制备方法及应用
WO2024098294A1 (fr) * 2022-11-09 2024-05-16 宁德时代新能源科技股份有限公司 Ensemble feuille d'électrode négative et procédé de stockage de feuille d'électrode négative enrichie en lithium

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