JP6850621B2 - Lithium ion battery - Google Patents

Description

The present invention relates to a lithium ion battery having a cell cell in which a positive electrode current collector, a positive electrode active material layer, a separator, a negative electrode active material layer and a negative electrode current collector are laminated in this order and contains an electrolytic solution.

Lithium-ion (secondary) batteries have been widely used in various applications in recent years as high-capacity, compact and lightweight secondary batteries. Among these, as a small and thin lithium ion battery, a positive electrode having a positive electrode composition layer containing a positive electrode active material and an electrolytic solution formed on the surface of a positive electrode current collector, and a negative electrode containing a negative electrode active material and an electrolytic solution in the same manner. A substantially flat plate-shaped lithium secondary cell is manufactured in which a negative electrode having a composition layer formed on the surface of a negative electrode current collector is laminated with a separator sandwiched between them, and the positive electrode, the separator, and the ends of the negative electrode are sealed by a sealing portion. However, a plurality of layers of this lithium secondary cell were laminated to form a laminated battery module.

In such a lithium secondary cell, the electrolytic solutions of the positive electrode and the negative electrode are simply discharged from the gap of the seal portion generated as a result of the impact such as vibration being applied to the cell and the change with time of the seal portion. It may leak to the outside of the battery. If the electrolytic solution leaks to the outside, there is a risk that the characteristics of the lithium secondary cell will deteriorate.

As a method for preventing leakage of the electrolytic solution in such a lithium secondary battery, the seal layer is outside the cell in the plan view of the bipolar battery in which a plurality of lithium secondary batteries are laminated in the stacking direction of the positive electrode and the negative electrode. A bipolar battery that is exposed to the surface and further adheres to each other with adjacent seal layers in the stacking direction has been proposed (see Patent Document 1).

Japanese Unexamined Patent Publication No. 2005-190713

However, even with the above-mentioned conventional bipolar battery, even if the sealing performance of the sealing portion is improved, the possibility of leakage of the electrolytic solution cannot be eliminated when the sealing portion is damaged. Therefore, there has been a demand for a lithium secondary battery in which the electrolytic solution does not leak even if the seal portion is damaged.

The present invention has been made in view of the above-mentioned problems, and provides a lithium ion battery capable of sufficiently suppressing leakage of an electrolytic solution from the fixed portion even if the fixed portion changes with time or shape. , Is one of the purposes.

The present invention is applied to a lithium ion battery having a cell cell in which a positive electrode current collector, a positive electrode active material layer, a separator, a negative electrode active material layer and a negative electrode current collector are laminated in this order and contains an electrolytic solution. Then, it is arranged between the positive electrode current collector and the negative electrode current collector, and by embedding the end portion of the separator, the peripheral edge portion of the separator is fixed between the positive electrode current collector and the negative electrode current collector, and the positive electrode A fixing portion for sealing the active material layer, the separator, and the negative electrode active material layer is provided, and the positive electrode active material layer and the negative electrode active material layer are obtained by mixing the positive electrode active material particles and the negative electrode active material particles with an electrolytic solution, respectively. It is composed of a positive electrode composition and a negative electrode composition, and an electrolytic solution absorber that absorbs an electrolytic solution and retains at least a part thereof is provided between the fixed portion and the positive electrode current collector and / or the negative electrode current collector. This solves at least one of the above-mentioned problems.

In the lithium ion battery of the present invention, a place for communication with the outside is generated between the fixed portion and the positive electrode current collector and / or the negative electrode current collector, and the electrolytic solution tries to leak from the communication place. In this case, the electrolytic solution absorber provided in the fixed portion absorbs the electrolytic solution and prevents leakage to the outside.

Here, it is preferable that the electrolytic solution absorber is provided in the fixed portion in an endless annular shape. When the positive electrode current collector and / or the negative electrode current collector is formed in a substantially plate shape, the electrolytic solution absorber is provided on the contact surface between the fixed portion and the positive electrode current collector and / or the negative electrode current collector. Is preferable. Further, when the separator is formed in a substantially plate shape, the fixing portion is preferably formed in a frame shape that seals the peripheral portions of the positive electrode current collector and the negative electrode current collector. Further, it is preferable that the positive electrode current collector and / or the negative electrode current collector is provided with a groove formed in an endless annular shape on the peripheral edge thereof, and the electrolytic solution absorber is provided in this groove.

According to the present invention, it is possible to provide a lithium ion battery capable of sufficiently suppressing leakage of an electrolytic solution from the fixed portion even if the fixed portion changes with time or shape.

It is a partially cutaway perspective view which shows the cell 1 which the lithium ion battery which is 1st Embodiment of this invention has. It is sectional drawing which shows the fixed part of the cell 1 which the lithium ion battery which is 1st Embodiment has. FIG. 5 is a cross-sectional view showing a state in which an electrolytic solution absorber absorbs an electrolytic solution in a fixed portion of the cell 1 of the lithium ion battery according to the first embodiment. It is sectional drawing which shows the cell | cell which the lithium ion battery which is 2nd Embodiment of this invention has. It is sectional drawing which shows the fixed part of the cell cell which the lithium ion battery which is 2nd Embodiment has. It is sectional drawing which shows the state which the electrolytic solution absorber absorbed the electrolytic solution in the fixed part of the cell of the lithium ion battery which is 2nd Embodiment.

(First Embodiment)
The lithium ion battery according to the first embodiment of the present invention will be described in detail with reference to FIGS. 1 and 2. FIG. 1 is a partially cutaway perspective view showing a cell cell included in the lithium ion battery according to the first embodiment of the present invention, and FIG. 2 is a cross-sectional view showing a fixed portion of the cell cell included in the lithium ion battery according to the first embodiment. Is.

In the lithium ion battery of the present embodiment, which is a battery to which the present invention is applied, a single or a plurality of lithium secondary batteries 1 having a substantially flat plate shape, which are the single batteries described in these figures, are stacked in series. The stacked battery module is housed in a battery outer container that forms the outer shell of a lithium-ion battery.

Here, in the present invention, the lithium secondary cell is a positive electrode having a positive electrode composition layer containing a positive electrode active material and an electrolytic solution formed on the surface of a positive electrode current collector, and a negative electrode active material and an electrolytic solution. It is a battery having a structure in which a negative electrode having a negative electrode composition layer containing the above electrode formed on the surface of a negative electrode current collector is laminated via a separator, and is not provided with a battery container, a terminal arrangement, an electronic control device, or the like. The lithium secondary cell may be abbreviated as a cell.

As shown in detail in FIG. 1, the lithium secondary cell 1 is a substantially flat plate-shaped positive electrode active material layer containing a positive electrode active material and an electrolytic solution on the surface of a substantially rectangular flat plate-shaped positive electrode current collector 7. A substantially flat negative electrode, which is a negative electrode active material layer containing a negative electrode active material and an electrolytic solution on the surface of the positive electrode 2 on which the positive electrode composition layer 5 is formed and the negative electrode current collector 8 having a substantially rectangular flat plate shape. The negative electrode 3 on which the electrode composition layer 6 is formed is similarly laminated via a substantially flat plate-shaped separator 4, and is formed in a substantially rectangular flat plate shape as a whole. As a result, the lithium secondary cell 1 having the opposite positive electrode current collector 7 and the negative electrode current collector 8 in the outermost layer is configured.

More specifically, the positive electrode composition layer 5 and the negative electrode composition layer 6 are seal members having a substantially rectangular frame shape extending in the thickness direction of the lithium secondary cell 1 which is a fixed portion of the present invention. It is formed in 9, and the end portion of the separator 4 is also embedded in the seal member 9, and the peripheral edge portion of the separator 4 is fixed by the seal member 9. The positive electrode current collector 7 and the negative electrode current collector 8 are provided so as to cover the upper surface of the positive electrode composition layer 5 and the lower surface of the negative electrode composition layer 6 in FIG. 1, respectively, and the seal member 9 is provided. It is provided so as to cover the upper surface and the lower surface, and the positive electrode active material layer (positive electrode electrode composition layer 5), the separator 4, and the negative electrode active material layer (negative electrode electrode composition) are provided between the positive electrode current collector 7 and the negative electrode current collector 8. The layer 6) is sealed. Therefore, the seal member 9 is arranged between the positive electrode current collector 7 and the negative electrode current collector 8, and the peripheral edge portion of the separator 4 is fixed between the positive electrode current collector 7 and the negative electrode current collector 8 and the positive electrode is positive. It functions as a fixing portion for sealing the active material layer (positive electrode composition layer 5) and the negative electrode active material layer (negative electrode composition layer 6).

The positive electrode current collector 7 and the negative electrode current collector 8 are positioned so as to face each other at a predetermined interval by the seal member 9, and the separator 4, the positive electrode current collector 7, and the negative electrode current collector 8 are also predetermined by the seal member 9. It is positioned so as to face each other with an interval.

The distance between the positive electrode current collector 7 and the separator 4 and the distance between the negative electrode current collector 8 and the separator 4 are adjusted according to the capacity of the lithium ion battery, and these positive electrode current collector 7 and the negative electrode current collector 7 are adjusted. The positional relationship between the electric body 8 and the separator 4 is determined so that the required spacing can be obtained.

An electrolytic solution absorber 10 that absorbs the electrolytic solution and holds at least a part thereof is provided between the sealing member 9 and the positive electrode current collector 7 and / or the negative electrode current collector 8.

More specifically, as shown in detail in FIGS. 1 and 2, a cell 1 is formed on the upper surface and the lower surface in FIG. 2, which are contact surfaces of the sealing member 9 with the positive electrode current collector 7 and the negative electrode current collector 8. The groove portion is formed in an endless annular shape in a plan view (see FIG. 1), and the electrolytic solution absorber 10 is provided in this groove portion. Therefore, the electrolytic solution absorber 10 is provided in an endless annular shape on the contact surface of the seal member 9 with the positive electrode current collector 7 and the negative electrode current collector 8.

In the present invention, the positive electrode composition layer 5 which is the positive electrode active material layer and the negative electrode electrode composition layer 6 which is the negative electrode active material layer each use active material particles (positive electrode active material particles or negative electrode active material particles) as an electrolytic solution. It is obtained by molding a positive electrode composition or a negative electrode composition obtained by mixing into a sheet. A method of adding an electrolytic solution after forming powdery positive electrode active material particles and negative electrode active material particles into a sheet, and a sheet of positive electrode slurry or negative electrode slurry obtained by mixing the active material particles with a solvent. It can be obtained by a method of adding an electrolytic solution or the like after molding into.

When the sheet-shaped positive electrode composition layer 5 and the negative electrode composition layer 6 are molded, a binder (also referred to as a binder) may be used in the electrode composition or the electrode active material slurry. As the binder, known binders such as polyvinylidene fluoride and styrene-butadiene resin can be used.

The positive electrode composition contains positive electrode active material particles, and the positive electrode active material particles include composite oxides of lithium and a transition metal (for example, LiCoO ₂ , LiNiO ₂ , LiMnO ₂ , LiMn ₂ O ₄ and LiNi _0.8). Co _0.15 Al _0.05 O ₂ ), transition metal oxides (eg MnO ₂ and V ₂ O ₅ ), transition metal sulfides (eg MoS ₂ and TiS ₂ ) and conductive polymers (eg polyaniline, polypyrrole, etc.) Polythiophene, polyacetylene, poly-p-phenylene and polycarbazole) and the like can be mentioned. The volume average particle size of the positive electrode active material is preferably 0.1 to 100 μm, more preferably 1 to 50 μm, and even more preferably 2 to 20 μm from the viewpoint of the electrical characteristics of the battery.

The volume average particle size of the positive electrode active material means the particle size (Dv50) at an integrated value of 50% in the particle size distribution obtained by the laser diffraction / scattering method (also referred to as the microtrack method). The laser diffraction / scattering method is a method of obtaining a particle size distribution using scattered light obtained by irradiating particles with laser light, and for measuring the volume average particle size, a microtrack manufactured by Nikkiso Co., Ltd., etc. Can be used.

Further, the negative electrode electrode composition contains negative electrode active material particles, and as the negative electrode active material particles, graphite, non-graphitizable carbon, amorphous carbon, polymer compound calcined material (for example, phenol resin, furan resin, etc.) is calcined. Carbonized materials, etc.), cokes (eg, pitch coke, needle coke, petroleum coke, etc.), carbon fibers, conductive polymers (eg, polyacetylene and polyquinolin, etc.), tin, silicon, and metal alloys (eg, lithium-tin alloys). , Lithium-silicon alloy, lithium-aluminum alloy, lithium-aluminum-manganese alloy, etc.), composite oxide of lithium and transition metal (for example, Li ₄ Ti ₅ O ₁₂ etc.) and the like. The volume average particle size of the negative electrode active material is preferably 0.01 to 100 μm, more preferably 0.1 to 20 μm, and even more preferably 2 to 10 μm from the viewpoint of the electrical characteristics of the battery.

The volume average particle size of the negative electrode active material can be obtained in the same manner as that of the positive electrode active material.

The positive electrode active material particles and the negative electrode active material particles are preferably coated active material particles in which at least a part of the surface is coated with a coating layer made of a coating agent containing a coating resin. When the coating active material particles are used, the flexibility and conductivity of the positive electrode composition layer 5 and the negative electrode composition layer 6 are further improved, and the electrochemical reaction between the electrolytic solution and the active material generated during charging and discharging is suppressed. It is considered that the deterioration of the electrolytic solution can be suppressed and the cycle characteristics are improved.

In the present invention, the coating means a state in which the coating agent is attached to at least a part of the surface of the active material particles, and also includes a state in which the coating agent is scattered on the surface of the active material particles. The state in which the coating agent is attached to the surface of the active material particles can be confirmed by observing a magnified observation image of the coating active material particles obtained by using a scanning electron microscope or the like.

As the coating resin, a resin that absorbs the electrolytic solution and swells can be used, and specific examples thereof include vinyl resin, urethane resin, polyester resin, polyamide resin, epoxy resin, polyimide resin, silicone resin, and phenol. Examples thereof include resins, melamine resins, urea resins, aniline resins, ionomer resins, and polycarbonates. Among these, a vinyl resin is preferable, and a copolymer containing (meth) acrylic acid and an ester of a monoalcohol having 4 to 36 carbon atoms and (meth) acrylic acid as an essential constituent monomer is more preferable.

The coating agent may further contain a conductive auxiliary agent, and the conductive auxiliary agent can be selected and used from materials having conductivity.

Materials with conductivity include metals [aluminum, stainless steel (SUS), silver, gold, copper and titanium, etc.], conductive carbon [graphite, carbon black, acetylene black, vulcan (registered trademark), and ketjen black (registered). Trademarks), Black Pearl (registered trademark), Furness Black, Channel Black, Thermal Lamp Black, Carbon Nanotubes (Single-walled Carbon Nanotubes and Multi-walled Carbon Nanotubes, etc.), Carbon Nanohorns, Carbon Nanoballoons, Hard Carbon, Fullerenes, etc.], and these Examples thereof include, but are not limited to these.

These conductive aids may be used alone or in combination of two or more. Moreover, these alloys or metal oxides may be used. From the viewpoint of electrical stability, aluminum, stainless steel, carbon, silver, gold, copper, titanium and mixtures thereof are preferable, silver, gold, aluminum, stainless steel and carbon are more preferable, and carbon is more preferable. is there. The conductive auxiliary agent includes a non-conductive material such as a particle-based ceramic material and a resin material coated with a conductive material (a metal material among the above-mentioned conductive auxiliary agent materials) by plating or the like, and a non-conductive material. A mixture of a conductive material and a conductive material (a metal material among the above-mentioned conductive aid materials) can also be used.

The shape of the conductive auxiliary agent is not particularly limited, and those having a shape such as a spherical shape, an indefinite shape, a fibrous shape, a single particle shape, an agglomerate, or a combination thereof can be used. Therefore, it is preferable that it is an agglomerate of fine particles having a primary particle diameter of 5 to 50 nm. The shape of the conductive auxiliary agent can be obtained by observing a magnified observation image of the conductive auxiliary agent obtained by using a scanning electron microscope or the like and measuring the particles in the field of view.

When the coating agent contains a coating resin and a conductive auxiliary agent, the weight ratio of the coating resin and the conductive auxiliary agent contained in the coating agent is preferably coating resin: conductive auxiliary agent = 100: 1 to 100: 200. , More preferably 100: 5 to 100: 100. Within this range, the conductivity of the positive electrode composition layer 5 and the negative electrode composition layer 6 becomes good.

The coating active material particles are, for example, a resin in which positive electrode active material particles or negative electrode active material particles are placed in a universal mixer and stirred at 30 to 500 rpm, and a coating resin and a conductive auxiliary agent used as necessary are mixed with an organic solvent. The solution is added dropwise over 1 to 90 minutes, and if necessary, the conductive additive to be used is mixed, the temperature is raised to 50 to 200 ° C. with stirring, the pressure is reduced to 0.007 to 0.04 MPa, and then 10 to 150 minutes. It can be obtained by holding.

The proportion of the coating resin contained in the resin solution is preferably 10 to 50% by weight based on the weight of the resin solution. As the organic solvent used in the resin solution, an organic solvent capable of dissolving the coating resin can be selected.

It can be confirmed that the coating active material particles are obtained by observing the magnified observation image of the coating active material particles obtained by using a scanning electron microscope or the like.

When the positive electrode composition and the negative electrode composition are formed, respectively, as the positive electrode composition and the negative electrode composition, the positive electrode active material particles and the negative electrode active material particles are mixed with an electrolytic solution or a non-aqueous solvent, respectively. It is preferably a mixture obtained, and more preferably a slurry-like mixture. In this case, the weights of the positive electrode active material particles and the negative electrode active material particles contained in the positive electrode composition and the negative electrode composition are preferably 10 to 60% by weight based on the weight of the electrolytic solution or the non-aqueous solvent. ..

As the electrolytic solution, a known electrolytic solution obtained by mixing an electrolyte and a non-aqueous solvent used in the production of a known lithium ion battery can be used.

As the electrolyte, a normal is can be used such as those used in the electrolytic solution, the lithium salt of an inorganic acid _{(LiPF 6, LiBF 4, LiSbF} 6, LiAsF 6 , and LiClO _4, etc.) and a lithium salt of an organic acid [LiN ( CF ₃ SO ₂ ) ₂ , LiN (C ₂ F ₅ SO ₂ ) _2, LiC (CF ₃ SO ₂ ) _3, etc.], etc., and one of these electrolytes may be used alone or two. The above may be used together. _{Among these, LiPF 6} is preferable from the viewpoint of battery output and charge / discharge cycle characteristics.

As the non-aqueous solvent, those used in ordinary electrolytic solutions can be used, and lactones, cyclic or chain carbonates, chain carboxylic acid esters, cyclic or chain ethers, phosphoric acid esters, nitrile compounds, and amides can be used. Compounds, sulfones, sulfolanes and the like and mixtures thereof and the like can be used. One of these non-aqueous solvents may be used alone, or two or more thereof may be used in combination.

Among the non-aqueous solvents, lactone, cyclic carbonate, chain carbonate and phosphoric acid ester are preferable from the viewpoint of battery output and charge / discharge cycle characteristics, and lactone, cyclic carbonate and chain carbonate are more preferable. It is an ester, and more preferably, a mixed solution of a cyclic carbonate ester and a chain carbonate ester. Particularly preferred is propylene carbonate (PC) or a mixture of ethylene carbonate (EC) and diethyl carbonate (DEC).

The concentration of the electrolyte contained in the electrolytic solution is preferably 0.1 to 3 mol / L, more preferably 0.5 to 2 mol / L, based on the volume of the electrolytic solution.

In the present invention, the positive electrode composition layer 5 and the negative electrode composition layer 6 preferably contain a fibrous conductive filler together with the above-mentioned coating active material particles from the viewpoint of reducing ionic resistance and the like. Examples of the fibrous conductive filler include carbon fibers such as PAN-based carbon fibers and pitch-based carbon fibers, conductive fibers obtained by uniformly dispersing a metal or graphite having good conductivity in synthetic fibers, and stainless steel. Examples thereof include metal fibers obtained by fiberizing metal, conductive fibers in which the surface of organic fibers is coated with metal, and conductive fibers in which the surface of organic fibers is coated with conductive resin. Among these conductive fibers, carbon fiber is preferable.

The fibrous conductive filler preferably has an average fiber length of 100 to 1000 μm, more preferably 110 μm to 600 μm, and particularly preferably 150 μm to 500 μm, from the viewpoint of ion resistance, strength of the active material layer, and the like. The average fiber diameter is preferably 0.1 to 100 μm, more preferably 0.5 to 2.0 μm.

When the positive electrode composition layer 5 and the negative electrode composition layer 6 contain the fibrous conductive filler, the proportion of the fibrous conductive filler is 0.5 to 5% by weight based on the weight of the coating active material particles. Is preferable.

When the positive electrode composition layer 5 and the negative electrode composition layer 6 contain a fibrous conductive filler, the positive electrode 2 and the negative electrode 3 each contain positive electrode active material particles, a fibrous conductive filler, and an electrolytic solution. It is preferable to fill the negative electrode composition containing the composition, the negative electrode active material particles, the fibrous conductive filler, and the electrolytic solution, respectively, to form the positive electrode composition layer 5 and the negative electrode composition layer 6.

The thickness of the positive electrode composition layer 5 and the negative electrode composition layer 6 is preferably 200 μm or more. It is more preferably 500 μm or more, still more preferably 1000 μm or more. If it is thicker than this thickness, the amount of active material per unit volume increases, and a battery having a large storage capacity can be obtained.

The separator 4 includes a hydrocarbon resin such as polyvinylidene fluoride-hexafluoropropylene (PVdF-HFP), a porous film made of polyolefin (polyethylene, polypropylene, etc.), and a multilayer film of a porous film (for example, PP / PE / Laminates having a three-layer structure of PP, etc.), non-woven fabrics made of synthetic fibers (polyester fibers, aramid fibers, etc.), glass fibers, etc., and those with ceramic fine particles such as silica, alumina, and titania attached to their surfaces, etc. A known separator for a lithium ion battery or the like can be used.

The thickness of the separator 4 can be adjusted depending on the use of the lithium ion battery, but in the use of electronic devices such as mobile devices, the thickness of the separator 4 is preferably 5 to 100 μm in a single layer or a multilayer, and more preferably 10 to 50 μm. Is.

The pore diameter of the separator 4 made of the porous film or the multilayer film thereof is preferably 1 μm or less (usually, the pore diameter is about several tens of nm) at the maximum. When a non-woven fabric is used, the thickness of the separator 4 is preferably 5 to 200 μm, particularly preferably 10 to 100 μm.

The positive electrode current collector 7 and the negative electrode current collector 8 are a metal current collector or a resin current collector, and are known metal current collectors, as well as Japanese Patent Publication No. 2012-150905 and International Publication No. WO2015 / 005116, respectively. The known resin current collectors and the like described in the above can be used.

As the metal collector, a metal collector generally used for lithium ion batteries can be used, and copper, aluminum, titanium, nickel, tantalum, niobium, hafnium, zirconium, zinc, tungsten, bismuth, antimon and these Examples thereof include alloys containing one or more and current collectors made of one or more metals selected from the group consisting of stainless alloys.

The form of the base material of the metal current collector may be any of a thin plate shape, a metal foil shape and a mesh shape, and a metal layer is formed on the surface of the base material of the metal current collector by a method such as sputtering, electrodeposition and coating. May be formed.

The resin current collector is a current collector formed of a conductive polymer material or a polymer obtained by imparting conductivity to a non-conductive polymer material.

Examples of the conductive polymer material include polyaniline, polypyrrole, polythiophene, polyacetylene, polyparaphenylene, polyphenylene vinylene, polyacrylonitrile, polyoxadiazole and the like. For the purpose of improving the conductivity of the resin current collector containing the conductive polymer material, it is preferable to further contain a conductive filler described later.

Non-conductive polymer materials include polyethylene (PE), polypropylene (PP), polymethylpentene (PMP), polycycloolefin (PCO), polyethylene terephthalate (PET), polyether nitrile (PEN), and polytetrafluoroethylene. (PTFE), styrene butadiene rubber (SBR), polyacrylic nitrile (PAN), polymethyl acrylate (PMA), polymethyl methacrylate (PMMA), polyvinylidene fluoride (PVdF), epoxy resin, silicone resin and mixtures thereof. Be done.

As the non-conductive polymer material, polyethylene (PE), polypropylene (PP), polymethylpentene (PMP) and polycycloolefin (PCO) are preferable, and polyethylene (PE) is more preferable from the viewpoint of electrical stability. , Polypropylene (PP) and Polymethylpentene (PMP).

The polymer obtained by imparting conductivity to the non-conductive polymer material can be obtained by mixing the non-conductive polymer material and the conductive filler, and the conductive filler is obtained from the material having conductivity. Selected from fillers. Preferably, from the viewpoint of suppressing ion permeation in the current collector, it is preferable to use a filler obtained from a material having no conductivity with respect to ions used as a charge transfer medium. Specific examples thereof include fillers obtained from carbon materials, alloy materials such as aluminum, gold, silver, copper, iron, platinum, chromium, tin, indium, antimony, titanium, nickel and stainless steel (SUS). It is not limited to these. Among them, from the viewpoint of corrosion resistance, a filler obtained from aluminum, stainless steel, a carbon material or nickel is preferable, and a filler obtained from a carbon material is more preferable. These conductive fillers may be used alone or in combination of two or more. As the conductive filler, a particle-based ceramic material or a resin material coated with the metal shown above by plating or the like can also be used.

The shape of the conductive filler may be a particle shape, a fibrous shape, or an aggregate thereof.

The resin current collector can be obtained by a known method described in Japanese Patent Publication No. 2012-150905 and International Publication No. WO 2015/005116, and as a specific example, acetylene black as a conductive filler in polypropylene can be obtained. After dispersing 5 to 20 parts of the above, rolled with a hot press machine and the like can be mentioned. Further, the thickness thereof is not particularly limited, and the same as known ones or appropriately modified ones can be applied.

As the positive electrode current collector 7 and the negative electrode current collector 8, the metal current collector or the resin current collector may be used as they are, or those having a conductive layer to be described later may be used on the surface thereof, from the viewpoint of battery characteristics and the like. Therefore, it is preferable that it is a metal current collector or a resin current collector on which a conductive layer is formed.

The material constituting the seal member 9 is not particularly limited as long as it is a material durable to the electrolytic solution, but a polymer material is preferable, and a thermosetting polymer material is more preferable. Specific examples thereof include epoxy-based resins, polyolefin-based resins, polyurethane-based resins, and polyvinylidene fluoride resins, and epoxy-based resins are preferable because they have high durability and are easy to handle.

The electrolytic solution absorber 10 can be used without limitation as long as it is a material capable of absorbing the electrolytic solution contained in the positive electrode composition layer 5 and the negative electrode composition layer 6, but the preferred material is International Publication No. 2015/005117. The polymer compound described as the resin for coating the active material of the lithium ion battery described in No. can be used, and among them, vinyl resin and urethane resin are preferable, and (meth) acrylic acid and mono having 4 to 36 carbon atoms are used. A copolymer containing an ester of alcohol and (meth) acrylic acid as an essential constituent monomer is more preferable.
These polymer compounds can change from a solid state to a swollen state by absorbing the electrolytic solution, and are preferable as an electrolytic solution absorber.

Next, a method for manufacturing the lithium secondary cell 1 having the above configuration will be described.

First, the solid electrolyte absorber 10 is arranged in an endless annular shape on the peripheral edge of one surface of the negative electrode current collector 8, and the seal member 9 is formed on the solid electrolyte absorber 10. The method of arranging the electrolytic solution absorber 10 on the negative electrode current collector 8 and the method of forming the seal member 9 are arbitrary, but as an example, the printing device such as an inkjet machine or a 3D printer and the nozzle are moved and controlled to a predetermined position. A method of discharging the member forming the electrolytic solution absorber 10 or the seal member 9 by a device or the like having a mechanism capable of discharging a predetermined amount of the member is preferably mentioned.

After the sealing member 9 was formed to a height at which the negative electrode composition layer 6 should be formed, the sealing member 9 was formed on the negative electrode composition layer 6 which is a negative electrode active material layer containing the negative electrode active material and the electrolytic solution. It is formed on one surface of the negative electrode current collector 8 to form the negative electrode 3. The method of forming the negative electrode 3 is arbitrary, and the negative electrode composition is applied to one surface of the negative electrode current collector 8, and after the negative electrode composition is placed on one surface of the negative electrode current collector 8 via a nozzle or the like. Various methods can be mentioned, such as leveling with a spatula or the like so as to have a predetermined thickness.

Next, the separator 4 is placed so as to cover one surface of the negative electrode composition layer 6 forming the negative electrode 3 on the side opposite to the negative electrode current collector 8 and to place the end portion on the end portion of the seal member 9. Place. The method of placing the separator 4 on one surface of the negative electrode composition layer 6 is arbitrary. As an example, one surface of the separator 4 is held by a vacuum chuck, and the separator 4 is mounted on the negative electrode composition layer 6 using this vacuum chuck. A method in which the chuck is removed from the separator 4 after being placed on one surface is preferably mentioned.

Next, the sealing member 9 is further formed on one surface of the separator 4, and the sealing member 9 is formed to a height at which the positive electrode composition layer 5 should be formed. A certain positive electrode composition layer 5 is formed on one surface of the separator 4 opposite to the negative electrode composition layer 6 to form the positive electrode 2. Since the method of forming the positive electrode 2 is substantially the same as the method of forming the negative electrode 3, the description thereof will be omitted here.

Next, the positive electrode composition layer 5 for forming the positive electrode 2 is formed after the electrolytic solution absorber 10 in a solid state is arranged in an endless annular shape on the seal member 9 formed to a height at which the positive electrode composition layer 5 should be formed. The positive electrode current collector 7 is placed so that one surface is covered, the end portion covers the electrolytic solution absorber 10, and the end portion is placed on the end portion of the seal member 9. The method of arranging the electrolytic solution absorber 10 is substantially the same as the method of arranging the electrolytic solution absorber 10 on one surface of the negative electrode current collector 8, and the positive electrode current collector 7 is placed on one surface of the positive electrode composition layer 5. Since the mounting method is substantially the same as the method of mounting the separator 4 on one surface of the negative electrode composition layer 6, the description thereof will be omitted here. As a result, the lithium secondary cell 1 shown in FIG. 1 can be manufactured.

The lithium ion battery of the present embodiment can be obtained by accommodating the lithium secondary cell shown in FIG. 1 in a battery outer container. The battery outer container is selected from the viewpoint that the positive electrode composition layer 5 and the negative electrode composition layer 6 can be stably stored in the container, and it is particularly preferable to have flexibility. .. In addition, the battery outer container is preferably made of an insulating material in consideration of the possibility of contact between the electrode composition and the battery outer container, and the positive electrode current collector 7 and the positive electrode composition layer 5 are used. , Separation 4, negative electrode composition layer 6 and negative electrode current collector 8 are laminated in this order, and the power generation element is sealed (preferably reduced pressure sealing) in a state of being housed inside. It is preferably composed of the material to be provided.

The battery outer container is preferably a container made of a laminated film, and as the laminated film, a composite film having a metal layer interposed between an outer layer containing a heat-resistant resin film and an inner layer containing a thermoplastic resin film is used. As the heat-resistant resin film, a stretched film of polyamide resin or polyester resin can be preferably used, and as the thermoplastic resin film, an unstretched polyolefin film or the like can be preferably used.

As the metal layer, a layer made of aluminum foil, stainless steel foil, copper foil or the like can be used. The heat-resistant resin film means that the melting point of the resin film is higher than the melting point of the thermoplastic resin film as the inner layer, and when the heat-resistant resin film is used as the outer layer, the thermoplastic resin film becomes the inner layer. Only the resin film can be sufficiently heated and melted, and the heat seal of the battery outer container can be reliably performed.

As an example of the laminated film, a heat-resistant resin (polyethylene resin, polyester resin, etc.) is coated on the first surface of the metal layer such as aluminum or nickel, which is the outer surface of the battery outer container, and the inner surface of the battery outer container is coated. A film coated with a thermoplastic resin (polyethylene, polypropylene, etc.) is raised on the second surface.

In the lithium ion battery of the present embodiment having the above configuration, the seal member 9 is, for example, as shown in FIG. 3, due to an impact such as vibration being applied to the cell 1 or a change with time of the seal portion. A gap is formed on the contact surface between the positive electrode current collector and the positive electrode current collector 7, and the electrolytic solution forming the positive electrode composition layer 5 and the negative electrode composition layer 6 (in the example shown in FIG. 3, the electrolysis forming the positive electrode composition layer 5). When the liquid) leaks to the seal member 9, the electrolytic solution absorber 10 absorbs the electrolytic solution, closes the seal member 9 as a swelling body, and the electrolytic solution absorber 10 holds the electrolytic solution. As a result, leakage of the electrolytic solution from the sealing member 9 is suppressed as much as possible.

Therefore, according to the lithium ion battery of the present embodiment, the characteristics are deteriorated even when a gap is formed between the seal member 9 which is a fixed portion and the positive electrode current collector 7 and / or the negative electrode current collector 8. It is possible to realize a lithium ion battery that can be suppressed. Moreover, even if the seal member 9 is damaged, the electrolytic solution leakage ability of the electrolytic solution absorber 10 is not reduced.

Therefore, according to the present embodiment, it is possible to realize a lithium ion battery capable of sufficiently suppressing leakage of the electrolytic solution from the fixed portion even if the fixed portion changes with time or shape.

(Second Embodiment)
Next, the cell cell included in the lithium ion battery according to the second embodiment of the present invention will be described in detail with reference to FIGS. 4 to 6. FIG. 4 is a sectional view showing a cell of the lithium ion battery according to the second embodiment of the present invention, and FIG. 5 is a sectional view showing a fixed portion of the cell of the lithium ion battery of the second embodiment, FIG. Is a cross-sectional view showing a state in which the electrolytic solution absorber absorbs the electrolytic solution in the fixed portion of the cell cell of the lithium ion battery according to the second embodiment.

In these figures, the positive electrode current collector 7 and the negative electrode current collector 8 located outside the cell of the lithium ion battery of the present embodiment each contain an active material composition, as shown in detail in FIG. It is formed in a predetermined shape having a portion. The accommodating portions of the positive electrode current collector 7 and the negative electrode current collector 8 are formed to have substantially the same shape, and the positive electrode current collector 7 and the negative electrode current collector 8 have the main body 7a having the accommodating portions. 8a and a pair of upper edge portions 7b and lower edge portions 8b, which are outer peripheral portions of the accommodating portion, are provided so as to project laterally from the left and right end portions in FIG. A hollow housing portion 21 is formed by the positive electrode current collector 7 and the negative electrode current collector 8 on which the housing portion and the edge portion are formed.

A substantially flat plate-shaped separator 4 is arranged in the accommodating portion 21, and the accommodating portion 21 is divided into a positive electrode chamber and a negative electrode chamber.

The positive electrode chamber and the negative electrode chamber are filled with a positive electrode composition layer 5 which is a positive electrode active material layer and a negative electrode composition layer 6 which is a negative electrode active material layer, respectively. The positive electrode 2 composed of the layer 5, the separator 4, the negative electrode composition layer 6 and the negative electrode 3 composed of the negative electrode current collector 8 are laminated in this order to form the cell cell of the present embodiment containing the electrolytic solution. Then, in a state where the end portion of the separator 4 is arranged between the upper edge portion 7b and the lower edge portion 8b, the space between the upper edge portion 7b and the lower edge portion 8b is sealed by the sealing member 9. Therefore, the cell cell of the lithium ion battery of the present embodiment is formed.

Therefore, the seal member 9 is arranged between the positive electrode current collector 7 and the negative electrode current collector 8, and the peripheral edge portion of the separator 4 is fixed between the positive electrode current collector 7 and the negative electrode current collector 8 and the positive electrode is positive. It functions as a fixing portion for sealing the active material layer (positive electrode composition layer 5) and the negative electrode active material layer (negative electrode composition layer 6).

As shown in detail in FIGS. 4 and 5, the sealing member 9 is provided with an electrolytic solution absorber 10 that absorbs the electrolytic solution and holds at least a part thereof.

More specifically, the seal member 9 extends in an endless annular shape over the entire outer peripheral portion of the positive electrode current collector 7 and the negative electrode current collector 8, and the electrolytic solution absorber 10 has an endless annular shape along the seal member 9. It is provided. Further, the upper edge portion 7b of the positive electrode current collector 7 and the lower edge portion 8b of the negative electrode current collector 8 are provided with groove portions 7c and 8c formed in an endless annular shape, respectively, as shown in FIGS. 4 and 5, respectively. The electrolytic solution absorber 10 is preferably provided so as to fill the hollow portion formed between the two groove portions 7c and 8c.

In the present invention, the positive electrode composition layer 5 and the negative electrode composition layer 6 can also be obtained by directly filling the positive electrode chamber and the negative electrode chamber with the electrode composition.

Here, in the present specification, "filled" means a state in which the positive electrode active material particles and the negative electrode active material particles are housed in the positive electrode chamber and the negative electrode chamber, respectively, and preferably the positive electrode active material particles. It means that the negative electrode active material particles and the electrolyte are housed in the positive electrode chamber and the negative electrode chamber, respectively. More preferably, it means a state in which the positive electrode active material particles and the negative electrode active material particles and the electrolyte are mixed.

In the present invention, in order to fill the positive electrode chamber and the negative electrode chamber with the positive electrode composition layer 5 and the negative electrode composition layer 6, powdered positive electrode active material particles and negative electrode active material particles are directly placed in the positive electrode chamber and the negative electrode chamber. It may be put in each of the negative electrode chambers, or it may be done by putting the slurry positive electrode electrode composition and the negative electrode composition containing the positive electrode active material or the negative electrode active material particles and the electrolytic solution in the positive electrode chamber and the negative electrode chamber, respectively. .. When the powdery positive electrode active material and the negative electrode active material particles are directly put into the positive electrode chamber and the negative electrode chamber, and then the electrolytic solution is put into the positive electrode chamber and the negative electrode chamber, respectively, the positive electrode composition layer 5 and the negative electrode composition Layer 6 is filled.

Further, the groove portions 7c and 8c can be provided by molding the outer peripheral portion of the current collector by a method such as embossing in an endless annular shape.

Next, a method for manufacturing the lithium ion battery of the present embodiment will be described.

First, it is an accommodating portion of the main bodies 7a and 8a of the positive electrode current collector 7 and the negative electrode current collector 8 which are formed in a predetermined shape and have grooves 7c and 8c formed in the upper edge portion 7b and the lower edge portion 8b, respectively. The recesses are filled with the positive electrode composition and the negative electrode composition, respectively, to form the positive electrode composition layer 5 which is the positive electrode active material layer and the negative electrode composition layer 6 which is the negative electrode active material layer. The method of filling the positive electrode composition and the negative electrode composition into the recesses is not limited, and as an example, a method of filling the positive electrode composition and the negative electrode composition from a tank in which the positive electrode composition and the negative electrode composition are stored via a nozzle, an inkjet device, or the like. Therefore, a method of filling the recesses of the positive electrode current collector 7 and the negative electrode current collector 8 with the positive electrode composition and the negative electrode composition, and a well-known method are preferably applied.

The amount of the positive electrode composition and the negative electrode composition layer filled in the recesses of the positive electrode current collector 7 and the negative electrode current collector 8 is at least such that the recesses are filled with the positive electrode composition and the negative electrode composition. The amount of the positive electrode composition and the negative electrode composition is preferably such that the positive electrode composition and the negative electrode composition are slightly raised from each of the upper edge portion 7b and the lower edge portion 8b.

Next, by arranging the flat plate-shaped separator 4 on the upper surface of either the positive electrode current collector 7 or the negative electrode current collector 8, the upper surface of either the positive electrode composition layer 5 or the negative electrode composition layer 6 is arranged. Is covered with the separator 4. At this time, when the positive electrode or negative electrode composition layers 5 and 6 are filled in the recesses in an amount sufficient to rise from the upper edge portion 7b and the lower edge portion 8b as described above, the upper surface of the separator 4 is pressed by a roller. It is preferable to level the positive electrode or negative electrode composition layers 5 and 6 by arranging the separator 4.

Next, the hollow portion formed between the grooves 7c and 8c of the upper edge portion 7b and the lower edge portion 8b is filled with the electrolytic solution absorber 10 in an endless ring shape, and the upper edge portion 7b and the lower edge portion 8b are sealed. After arranging the members 9 in an endless annular shape, either the positive electrode current collector 7 on which the positive electrode composition layer 5 is formed or the negative electrode current collector 8 on which the negative electrode composition 6 is formed is inverted upside down to form an upper edge portion. 7b and the lower edge portion 8b are arranged so as to face each other. In this state, the inside of the accommodating portion 21 formed by the accommodating portions of the positive electrode current collector 7 and the main bodies 7a and 8a of the negative electrode current collector 8 is degassed, and the sealing member 9 is adhered and sealed by heating and melting. By stopping, it is possible to obtain a lithium secondary cell used for the lithium ion battery as shown in FIG. 5 according to the second embodiment.

The lithium ion battery of the present embodiment can be obtained by housing the above-mentioned lithium secondary cell in a battery outer container similar to the battery outer container exemplified in the first embodiment.

Also in the lithium ion battery of the present embodiment, as shown in FIG. 6, for example, the seal member 9 and the upper edge portion 7b are given an impact such as vibration to the lithium ion battery or the seal portion changes with time. A gap is formed on the contact surface with the positive electrode, and the electrolytic solution forming the positive electrode composition layer 5 and the negative electrode composition layer 6 (in the example shown in FIG. 6, the electrolytic solution forming the positive electrode composition layer 5) is the sealing member. When the leakage occurs to 9, the electrolytic solution absorber 10 absorbs the electrolytic solution, closes the sealing member 9 as a swelling body, and the electrolytic solution absorber 10 holds the electrolytic solution. As a result, leakage of the electrolytic solution from the sealing member 9 is suppressed as much as possible.

Therefore, the lithium ion battery of the present embodiment can also obtain the same effect as the lithium ion battery of the first embodiment described above.
(Modification example)

The details of the lithium ion battery of the present invention are not limited to the above-described embodiments, and various modifications are possible. As an example, the outer shape of the lithium ion battery of the present invention is not limited to that of the lithium ion battery as shown in FIGS. 1 and 4, and various outer shapes can be adopted.

1 Single battery 2 Positive electrode 3 Negative electrode 4 Separator 5 Positive electrode active material layer 6 Negative electrode active material layer 7 Positive electrode current collector 7c, 8c Groove 8 Negative electrode current collector 9 Sealing member 10 Electrolyte absorber

Claims (5)

A lithium ion battery in which a positive electrode current collector, a positive electrode active material layer, a separator, a negative electrode active material layer, and a negative electrode current collector are laminated in this order and has a single battery containing an electrolytic solution.
It is arranged between the positive electrode current collector and the negative electrode current collector, and by embedding the end portion of the separator, the peripheral edge portion of the separator is fixed between the positive electrode current collector and the negative electrode current collector. Moreover, the positive electrode active material layer, the separator, and the fixing portion for sealing the negative electrode active material layer are provided.
The positive electrode active material layer and the negative electrode active material layer are composed of a positive electrode electrode composition and a negative electrode composition obtained by mixing positive electrode active material particles and negative electrode active material particles with the electrolytic solution, respectively.
A lithium ion battery in which an electrolytic solution absorber that absorbs the electrolytic solution and holds at least a part thereof is provided between the fixed portion and the positive electrode current collector and / or the negative electrode current collector. In the lithium ion battery according to claim 1,
The electrolyte absorber is a lithium ion battery provided in the fixed portion in an endless annular shape. In the lithium ion battery according to claim 1 or 2.
The positive electrode current collector and / or the negative electrode current collector is formed in a substantially plate shape.
The electrolytic solution absorber is a lithium ion battery provided on a contact surface between the fixed portion and the positive electrode current collector and / or the negative electrode current collector. In the lithium ion battery according to claim 3.
The separator is formed in a substantially plate shape and has a substantially plate shape.
The fixed portion is a lithium ion battery formed in a frame shape that seals the peripheral portions of the positive electrode current collector and the negative electrode current collector. In the lithium ion battery according to claim 2.
The positive electrode current collector and / or the negative electrode current collector is provided with a groove formed in an endless annular shape on the peripheral edge thereof, and the electrolytic solution absorber is a lithium ion battery provided in the groove.

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