WO2013141242A1

WO2013141242A1 - Lithium ion secondary battery using ionic liquid, lithium ion secondary battery module, and heat retention device for lithium ion secondary battery using ionic liquid or for lithium ion secondary battery module

Info

Publication number: WO2013141242A1
Application number: PCT/JP2013/057826
Authority: WO
Inventors: 佐藤　明; 西村　拓也
Original assignee: 新神戸電機株式会社
Priority date: 2012-03-21
Filing date: 2013-03-19
Publication date: 2013-09-26
Also published as: JPWO2013141242A1

Abstract

Provided are: a lithium ion secondary battery which uses an ionic liquid that is capable of achieving high output power; and a lithium ion secondary battery module. A cylindrical lithium ion secondary battery which is increased in heat insulation properties by having the main part of a cylindrical lithium ion secondary battery main body (1) contained in a cylindrical vacuum heat insulation container (3) that is formed of a stainless steel heat insulation material.

Description

Lithium ion secondary battery and lithium ion secondary battery module using ionic liquid, and their heat insulation devices

The present invention relates to a lithium ion secondary battery and a lithium ion secondary battery module using an ionic liquid, and a heat retaining device thereof.

Non-aqueous electrolyte secondary batteries such as lithium ion batteries have the advantages of high energy density, low self-discharge and good cycle performance. Therefore, in recent years, non-aqueous electrolyte secondary batteries are expected to be used as power sources for various industrial machinery by increasing the size or capacity.

Examples of the non-aqueous solvent used in the non-aqueous electrolyte of such a lithium ion secondary battery include polar aprotic organic solvents such as ethylene carbonate and diethyl carbonate that easily dissolve lithium salts and are not easily electrolyzed. in use. However, conventionally used organic solvents have a very low flash point, and have flammability and flammability. Therefore, there are cases where ignition, explosion, etc. may occur due to overheating or short circuit. Therefore, in the conventional lithium ion secondary battery, ensuring safety is an important issue.

In order to solve this problem, various studies have recently been made on the use of ionic liquids as non-aqueous electrolytes for lithium ion secondary batteries. An ionic liquid is an ionic substance that shows a liquid state even at room temperature, and has not only a feature that is excellent in the output of a lithium ion secondary battery that is highly conductive, but also a lithium ion secondary that is low in vapor pressure, non-volatile and flame retardant. It also has excellent characteristics for the safety of secondary batteries. Japanese Patent Laying-Open No. 2010-287380 (Patent Document 1) discloses a lithium ion secondary battery using an ionic liquid as a nonaqueous electrolytic solution.

JP 2010-287380 A

However, a lithium ion secondary battery using an ionic liquid has a problem that its output is lower than that of a lithium ion secondary battery and a lead battery using an organic solvent, and it is difficult to put into practical use. There are various causes for the low output, but the main cause is considered to be the viscosity of the ionic liquid.

Since lithium ion secondary batteries are charged and discharged by movement of lithium ions between the positive electrode and the negative electrode, the ionic conductivity greatly affects the battery performance. In general, ionic conductivity is proportional to the reciprocal of the viscosity of the liquid. The viscosity of the ionic liquid is 10 times that of carbonate, which is a commonly used solvent for the electrolyte. Therefore, when an ionic liquid is used as a non-aqueous electrolyte, there is a problem in that the movement of lithium ions in the ionic liquid is limited, the conductivity is lowered, and the output of the lithium ion secondary battery is lowered. In addition, since the surface tension increases when the viscosity is high, the wettability with respect to the separator, which is a porous body used in the conventional lithium ion secondary battery, and the positive electrode material and the negative electrode material is deteriorated. The output may further decrease. Therefore, in the conventional lithium ion secondary battery using an ionic liquid, the output is about one-tenth that of a lithium ion secondary battery using an organic solvent, and a desired output cannot be obtained. Has occurred.

An object of the present invention is to provide a lithium ion secondary battery and a lithium ion secondary battery module using an ionic liquid capable of obtaining a higher output than before, and a heat insulating device for these.

Another object of the present invention is to provide a lithium ion secondary battery and a lithium ion secondary battery module that can maintain the viscosity of the ionic liquid at a low level, and a heat retaining device thereof.

Still another object of the present invention is to provide a lithium ion secondary battery and a lithium ion secondary battery module using the ionic liquid capable of keeping the ionic liquid at a temperature at which a high output can be obtained, and a heat insulation device thereof. There is to do.

When the temperature of the ionic liquid is higher than normal temperature, the output of the lithium ion secondary battery is good. The inventors have found that the reason why the output of the lithium ion secondary battery is good is that the viscosity of the ionic liquid decreases with increasing temperature. The present invention is based on such knowledge.

The lithium ion secondary battery using the ionic liquid of the present invention has a lithium ion battery main body and heat retaining means. In the lithium ion battery main body of the present invention, an ionic liquid is injected into the battery case as an electrolytic solution. The heat retaining means keeps the electrolyte at a predetermined temperature. With this configuration, the lithium ion secondary battery can be kept at a predetermined temperature higher than normal temperature, so the temperature of the ionic liquid inside the lithium ion secondary battery is also higher than normal temperature, and the viscosity of the ionic liquid Decreases. Therefore, the output of the lithium ion secondary battery using an ionic liquid can be made higher than the output at normal temperature.

The heat retaining means can be constituted by, for example, a heat insulating material that covers all or the main part of the battery case of the battery body. The heat insulating material can be attached to the battery case. Moreover, the heat insulating material can be in the shape of a heat insulating container having a housing part that houses the whole or main part of the battery case of the battery body. If comprised in this way, when the lithium ion secondary battery using an ionic liquid is charged / discharged, it can suppress that the heat which generate | occur | produced inside the battery main body is thermally radiated outside. Therefore, the lithium ion secondary battery using the ionic liquid can be kept at a temperature higher than room temperature with a simple configuration.

Depending on the environmental temperature of the battery, the ionic liquid may not be kept at a temperature at which sufficient output can be obtained with only the heat generated from the battery body. In such a case, the heat retaining means can further include a heating means for directly or indirectly heating the electrolytic solution. If comprised in this way, since the ionic liquid in a battery main body is heated positively, an ionic liquid can be heat-maintained to the temperature from which a sufficiently high output is obtained.

The heating means may use various heat media. Lithium ion secondary batteries are used in factories or homes. In the factory, exhaust heat of 100 ° C. or less (referred to as low temperature exhaust heat) from a boiler or other heat generating device is discharged. This waste heat can be used as a heat source for the heat medium. In the home, hot water of 60 ° C. heated by a water heater that uses heat generated during power generation provided in a household fuel cell can be used as a heat medium. Therefore, the heat retaining means is disposed in the housing part that accommodates all or the main part of the battery main body and in the interior of the housing part or the wall that surrounds the housing part, and heats the battery case accommodated in the housing part. And a heat medium circulation container comprising a circulation path through which the heat medium heated by the external heat source circulates. If comprised in this way, the waste heat and warm water discharged | emitted from the existing facility in a factory or a household can be utilized as a heat medium. Therefore, even when it is necessary to heat the battery body in order to maintain the temperature of the lithium ion secondary battery using the ionic liquid, the cost can be suppressed.

The present invention can also be applied to a lithium ion secondary battery module having an assembled battery composed of a plurality of lithium ion secondary batteries in which an ionic liquid is injected as an electrolyte into the battery case. In this type of lithium ion secondary battery module, if the temperature of the electrolyte solution of a plurality of lithium ion secondary batteries to be combined is different, the conduction characteristics of lithium ions in the electrolyte solution become uneven. In particular, when the electrolytic solution is an ionic liquid, if there is a temperature difference of several tens of degrees Celsius among a plurality of combined lithium ion secondary batteries, the ionic conductivity of the ionic liquid inside the lithium ion secondary battery is several tens of times There is a difference. Therefore, in the lithium ion secondary battery module, it is desired that the temperature difference between the plurality of lithium ion secondary batteries can be kept within 10 ° C. Therefore, when the present invention is applied to a lithium ion secondary battery module using an ionic liquid, the temperature of the electrolyte solution in the plurality of lithium ion secondary batteries is kept within a predetermined temperature range by the heat retaining means. With this configuration, since the outputs of the plurality of lithium ion secondary batteries do not differ greatly, not only can the output of the lithium ion secondary battery module using the ionic liquid be increased, but also a stable output can be obtained. Obtainable.

The heat retaining means used in the lithium ion secondary battery module can be constituted by a heat insulating material that covers at least a part of the assembled battery. Even in the case of the lithium ion secondary battery module, the heat insulating material may be attached to the battery case of the battery constituting the module. Moreover, you may comprise the heat insulation container which has an accommodating part which accommodates the whole or main part of an assembled battery with a heat insulating material. With this configuration, when the lithium ion secondary battery module is charged and discharged, heat generated from the assembled battery is not released to the outside of the heat insulating container. Therefore, the lithium ion secondary battery module can be kept at a temperature higher than room temperature with a simple configuration.

Further, the heat retaining means may further include a plurality of heating means for respectively heating the battery cases of the plurality of lithium ion secondary batteries constituting the assembled battery.

Also in the secondary battery module, it is possible to use a structure using a heat medium as a heating means. Specifically, the heat retaining means is disposed in the housing part that accommodates all or the main part of the assembled battery, and in the interior of the housing part or the wall that surrounds the housing part, and heats the assembled battery housed in the housing part. As described above, the heat medium circulation container includes a circulation path through which the heat medium heated by the external heat source circulates.

The present invention can also be specified as a heat retention device for a lithium ion secondary battery using an ionic liquid as an electrolytic solution or a heat retention device for a lithium ion secondary battery module using an ionic liquid as an electrolytic solution.

(A) is a figure which shows the cylindrical lithium ion secondary battery main body and cylindrical vacuum insulation container of Example 1 of this invention, (b) is a cylindrical lithium ion secondary battery main body in a cylindrical vacuum insulation container. It is a figure which shows the state accommodated. (A) is a figure which shows the cylindrical lithium ion secondary battery main body and cylindrical heat-medium circulation container of Example 2 of this invention, (b) is a cylindrical heat-medium circulation through a cylindrical lithium ion secondary battery main body. It is a figure which shows the state accommodated in the container. (A) is a figure which shows the cylindrical lithium ion secondary battery main body and cylindrical vacuum heat insulation container by which the heater of Example 3 of this invention was wound, (b) is the cylindrical lithium ion secondary by which the heater was wound. It is a figure which shows the state which accommodated the battery main body in the cylindrical vacuum heat insulation container. It is a figure which shows the square lithium ion secondary battery which affixed the heat insulating material of Example 4 of this invention. It is a figure which shows the square lithium ion secondary battery main body and square heat-medium circulation container of Example 5 of this invention. It is a figure which shows the square lithium ion secondary battery main body and heat insulating material which wound the heater of Example 6 of this invention. It is a figure which shows the laminate-type lithium ion secondary battery which affixed the heat insulating material of Example 7 of this invention. It is a figure which shows the lamination-type lithium ion secondary battery main body and square-shaped heat carrier circulation container of Example 8 of this invention. It is a figure which shows the laminate-type lithium ion secondary battery main body and heat insulating material which wound the heater of Example 9 of this invention. It is a figure which shows the lithium ion secondary battery module of Example 10 of this invention. It is a figure which shows the thermal-medium circulation container for modules of Example 11 of this invention. It is a figure which shows the lithium ion secondary battery module of Example 12 of this invention. It is a figure which shows the lithium ion secondary battery module main body and heat insulating material of Example 13 of this invention. It is a figure which shows the lithium ion secondary battery module main body of Example 14 of this invention, and the thermal-medium circulation container for modules. It is a figure which shows the lithium ion secondary battery module main body and heat insulating material of Example 15 of this invention. It is a figure which shows the lithium ion secondary battery module main body and heat insulating material of Example 16 of this invention. It is a figure which shows the lithium ion secondary battery module main body of Example 17 of this invention, and the thermal-medium circulation container for modules. It is a figure which shows the lithium ion secondary battery module main body and heat insulating material of Example 18 of this invention.

Hereinafter, the configuration of the embodiment of the lithium ion secondary battery, the lithium ion secondary battery module, and the heat retaining device using the ionic liquid of the present invention will be described in detail with reference to the drawings.

The lithium ion battery according to the embodiment of the present invention includes a battery body and a heat retention device. The battery body includes an electrode plate group including a positive electrode plate, a negative electrode plate, and a separator, an ionic liquid as an electrolytic solution, and a battery can as a battery case that accommodates the electrode plate group and the ionic liquid therein.

<Positive electrode plate>
The positive electrode plate is formed by applying a positive electrode mixture composed of a positive electrode active material, a conductive agent and a binder on both surfaces of an aluminum foil, followed by drying and pressing.

As the positive electrode active material, 1) one represented by the chemical formula LiMO ₂ (M is at least one transition metal) or 2) spinel manganese can be used. 3) A part of Mn, Ni, Co, etc. in the positive electrode active material such as lithium manganate, lithium nickelate, lithium cobaltate and the like can be substituted with one or more transition metals. . Further, a part of the transition metal of 3) substituted with a metal element such as Mg or Al can also be used. In addition to this, phosphate compounds, LiFePO ₄ , LiMnPO ₄ , LiMn _X M _1-X PO ₄ (0.3 ≦ x ≦ 1, M is Li, Fe, Ni, Co, Ti, Cu, Zn, Mg, And one or more elements selected from Zr) can be used.

As the conductive agent, a known conductive agent can be used. For example, a carbon-based conductive agent such as graphite, acetylene black, carbon black, or carbon fiber can be used. However, it is not limited to these materials.

As the binder, a known binder can be used. For example, polyvinylidene fluoride, fluororubber, or the like can be used. However, it is not limited to these materials. In the present invention, polyvinylidene fluoride is preferred.

As the solvent, a known solvent can be appropriately selected and used. In the present invention, it is preferable to use an organic solvent such as N-methyl-2-pyrrolidone.

The mixing ratio of the positive electrode active material, the conductive agent and the binder in the positive electrode mixture is, for example, 1: 0.05 to 0.20: 0.02 to 0.10 by weight when the positive electrode active material is 1. can do. However, it is not limited to this range.

<Negative electrode plate>
The negative electrode plate is formed by applying a negative electrode mixture comprising a negative electrode active material and a binder to both sides of a copper foil, and then drying and pressing.

As the negative electrode active material, 1) a carbon-based material such as graphite or amorphous carbon, 2) an oxide-based material such as lithium titanate, 3) a metal / alloy-based material such as tin or silicon should be used. Can do.

As the binder, for example, polyvinylidene fluoride, fluororubber, and the like can be used in the same manner as the positive electrode plate. However, it is not limited to these materials. In this invention, it is preferable that it is a polyvinylidene fluoride similarly to a positive electrode plate.

As the solvent, for example, a known solvent can be appropriately selected and used in the same manner as in the positive electrode plate. In the present invention, an organic solvent such as N-methyl-2-pyrrolidone is preferably used as in the negative electrode plate.

The mixing ratio of the negative electrode active material and the binder in the negative electrode mixture can be, for example, 1: 0.05 to 0.20 by weight when the negative electrode active material is 1. However, it is not limited to this range.

<Separator>
As the separator, a polyolefin-based porous film can be generally used, and for example, a composite film of polyethylene and polypropylene can be used. In addition, since the separator is required to have heat resistance, a ceramic composite separator in which a ceramic such as alumina is coated on the surface, and a ceramic composite separator using these as a part of the constituent material of the porous film may be used. However, the material of a separator is not limited to these, A well-known thing can be used.

<Electrolyte>
As the non-aqueous electrolyte, an ionic liquid that exhibits liquid properties at room temperature and a lithium salt dissolved therein is used. As the ionic liquid, [NR ¹ R ² R ³ R ⁴ ] ⁺ (R ¹ , R ² , R ³ , R ⁴ are alkyl groups having 1 to 4 carbon atoms, or a methoxy group in which a methoxy group is partially substituted. Piperidium or five-membered ring that is a chain-like quaternary ammonium cation represented by an alkyl group (— (CH ₂ ) _n OCH ₃ , n = 2 to 4)) or a nitrogen-containing cyclic compound The quaternary ammonium cation of pyrrolidinium ring and the inorganic anion BF ₄ ⁻ or the organic anion B (C ₆ H ₅ ) ₄ ⁻ , CH ₃ SO ₃ ⁻ , CF ₃ SO ₃ ⁻ , N (SO Any ionic liquid may be used as long as it is composed of ₂ F) ₂ ⁻ (FSI ⁻ ), N (SO ₂ CF ₃ ) ₂ ⁻ (TFSI ⁻ ), and N (SO ₂ CF ₂ CF ₃ ) ₂ ⁻ (BETI ⁻ ). For example, LiBF ₄ , LiClO ₄ , LiB (C ₆ H ₅ ) ₄ , LiCH ₃ SO ₃ , LiCF ₃ SO ₃ , LiN (SO ₂ F) ₂ , and LiN (SO ₂ ) One or more lithium salts selected from ₂ CF ₃ ) ₂ , LiN (SO ₂ CF ₂ CF ₃ ) _{2 and the} like can be dissolved to adjust the non-aqueous electrolyte.

<Battery can>
A known material can be used for the battery can. For example, it can be a laminated container using a metal container or an aluminum laminate in which a film is attached to an aluminum foil as an exterior material. The shape of the battery can can be cylindrical or rectangular.

<Insulation device>
The embodiment of the heat retaining device of the present invention can be a heat insulating container made of a heat insulating material, a heater that can be attached to the outer wall surface of the battery case, or a heat medium circulating container having a circulation path through which the heat medium circulates.

<Insulation material>
As the material of the heat insulating material, 1) a foam resin having heat insulating properties such as foamed urethane and polystyrene, and 2) a resin containing a core material and a core material such as glass wool and evacuating the inside are used. It is preferable to use a heat insulating material such as a vacuum heat insulating material made of an existing exterior material and used for a refrigerator, or 3) glass wool used for a house. As the heat insulating material, a material having particularly high heat insulating performance, that is, a material having low heat conductivity is preferable. For example, a heat insulating material having a heat conductivity of 0.02 W / (m · K) or less like a vacuum heat insulating material of a refrigerator is preferable.

Next, examples and comparative examples of the present invention will be described. In addition, this invention is not restrict | limited to the following Example.

First, a comparative experiment was conducted on a cylindrical lithium ion secondary battery.

<Example 1>
LiMn ₂ O ₄ was used as the positive electrode active material, and the positive electrode active material, the conductive material graphite, and the binder polyvinylidene fluoride were kneaded at a weight ratio of 85: 10: 5 for 30 minutes using a kneader. It was created. The obtained positive electrode mixture was applied to both surfaces of a current collector of aluminum foil having a thickness of 30 μm. The current collector coated with the positive electrode mixture was roll-formed with a press machine and then vacuum dried at 150 ° C. for 5 hours to obtain a positive electrode plate.

A graphite material was used as the negative electrode active material, and polyvinylidene fluoride was used as the binder. A negative electrode active material: binder = 90: 10 weight ratio was kneaded for 30 minutes using a kneader to prepare a negative electrode mixture. The obtained negative electrode mixture was applied to both sides of a 20 μm thick copper foil current collector. The current collector coated with the negative electrode mixture was roll-formed with a press machine and then vacuum dried at 150 ° C. for 5 hours to obtain a negative electrode plate.

The positive electrode plate and the negative electrode plate were overlapped and wound so as to be insulated through a separator made of a porous polymer resin film made of polyethylene (PE) and having a thickness of 20 μm to form a wound electrode plate group. The wound electrode plate group was inserted into a cylindrical battery can made of stainless steel.

The positive electrode plate was welded to an aluminum positive electrode current collector, and this positive electrode current collector was ultrasonically welded to the positive electrode pole column. After passing the positive electrode pole through the opening of the positive battery cover, the end of the positive electrode pole on the side where the positive electrode plate was not positioned was fixed with a positive hexagon nut serving as a positive electrode terminal.

The negative electrode plate was welded to an aluminum negative electrode current collector, and this negative electrode current collector was ultrasonically welded to the negative electrode pole column. After passing the negative electrode pole through the opening of the negative electrode battery cover, the end of the negative electrode pole on the side where the negative electrode plate was not positioned was fixed with a negative hexagon nut serving as a negative electrode terminal.

After ultrasonically welding the positive electrode battery cover and the negative electrode battery cover to the battery can, LiN (SO ₂ CF ₃ ) ₂ / Py13TFSI (lithium bis (trifluoromethanesulfonyl) imide / A lithium salt solution composed of N-methyl N-propylpyrrolidinium bis (trifluoromethanesulfonyl) imide) is injected as an ionic liquid, and a liquid injection port is screwed to form a cylinder with a battery capacity of 70 Ah shown in FIG. The main body 1 of a lithium ion secondary battery was obtained.

As shown in FIG. 1 (a), the main part of the cylindrical lithium ion secondary battery main body 1 is a cylindrical vacuum heat insulating container having a cylindrical peripheral wall 3A and a bottom wall 3B that closes one end of the peripheral wall 3A. 3 to obtain a cylindrical lithium ion secondary battery with improved heat insulation as shown in FIG. Each of the

peripheral wall portions

3A and 3B has a double wall structure facing each other with a vacuum space therebetween, and the double wall portion is made of stainless steel. In this embodiment, one terminal portion 2 of the cylindrical lithium ion secondary battery main body 1 is exposed from the opening of the cylindrical vacuum heat insulating container 3. The other terminal portion 4 of the cylindrical lithium ion secondary battery body 1 is electrically connected to the bottom wall portion 3B of the cylindrical vacuum heat insulating container 3. In the present embodiment, since the cylindrical vacuum heat insulating container 3 has conductivity, it electrically constitutes the other terminal electrode of the battery.

Using this cylindrical lithium ion secondary battery, a charge / discharge test was conducted with a termination condition of 4.2 V, a constant current constant voltage charge for 5 hours, and a constant current discharge of a termination condition of 3.0 V.

<Example 2>
A cylindrical lithium ion secondary battery main body 1 was produced in the same manner as in Example 1 (FIG. 2A). The main part of the lithium ion secondary battery body 1 was accommodated in the cylindrical heat medium circulation container 5 shown in FIG. 2A (FIG. 2B).

The cylindrical heat medium circulation container 5 has a cylindrical peripheral wall portion 5A and a bottom wall portion 5B that closes one end of the peripheral wall portion 5A. The

peripheral wall portions

5A and 5B have a double wall structure made of stainless steel, and each form a heat medium circulation space 5C between the double walls. A heat medium inlet port is provided at the end of the peripheral wall 5A on the opening side, and the heat medium introduction hose 7 is connected to the inlet port. A heat medium outlet port is provided at the end of the peripheral wall 5A on the bottom wall 5B side, and a heat medium discharge hose 9 is connected to the outlet port. In the present embodiment, the heat medium circulation space 5C constitutes a circulation path through which the heat medium can be circulated. Although not shown, the temperature of the electrolyte solution is indirectly measured by contacting the battery can 1A of the lithium ion secondary battery main body 1 and measuring the temperature of the battery can 1A inside the heat medium circulation vessel 5. A temperature sensor for measuring is disposed.

The heat medium is composed of water or silicone oil, and is heated to 50 to 70 ° C. by an external heat source (not shown) and introduced from the heat medium introduction hose 7 into the heat medium circulation container 5, so that the heat medium circulation container 5 is circulated through the heat medium discharge hose 9.

The heat medium was circulated by the cylindrical heat medium circulation container 5 so that the temperature of the accommodated cylindrical lithium ion secondary battery body 1 was 50 ° C. or higher, and the end condition of 4.2 V, as in Example 1, A charge / discharge test was conducted by constant current constant voltage charge for 5 hours and constant current discharge at a termination condition of 3.0 V.

<Example 3>
A cylindrical lithium ion secondary battery main body 1 was produced in the same manner as in Example 1 (FIG. 3A). A sheet-like heater 11 was wound around the outer wall surface of the battery can 1A of the lithium ion secondary battery body 1 as a heating means. The lithium ion secondary battery body 1 around which the heater 11 was wound was housed in a stainless steel cylindrical vacuum insulation container 3 in the same manner as in Example 1 to obtain a cylindrical lithium ion secondary battery with improved heat insulation. The power source of the heater 5 can utilize the lithium ion secondary battery body 1 itself. In FIG. 3, the electrical connection between the heater 11 and the battery body 1 is not shown.

Using this cylindrical lithium ion secondary battery, a charge / discharge test was conducted in the same manner as in Example 1 by a termination condition of 4.2 V, a constant current constant voltage charge for 5 hours, and a constant current discharge of a termination condition of 3.0 V.

<Comparative Example 1>
Cylindrical lithium ion secondary battery main body 1 produced in the same manner as in Example 1 has a termination condition of 4.2 V, a constant current and a constant voltage charge for 5 hours, and a termination condition as in Example 1, without imparting heat retention. A charge / discharge test using a constant current discharge of 3.0 V was performed.

Next, a comparative experiment was conducted on a prismatic lithium ion secondary battery.

<Example 4>
A plurality of positive electrode plates and a plurality of negative electrode plates made of the same material as in Example 1 are alternately stacked via separators of the same material as the separator used in Example 1, did. This electrode plate group was housed in a rectangular battery can body (not shown) made of stainless steel.

The positive electrode plate was welded to a positive electrode current collector (not shown) made of aluminum, and this positive electrode current collector was ultrasonically welded to the positive electrode pole column. The negative electrode plate was welded to a negative electrode current collector (not shown) of aluminum, and this negative electrode current collector was ultrasonically welded to the negative electrode pole column. After passing the positive electrode pole column and the negative electrode pole injection through two openings provided in the battery lid 13A, the end of the positive electrode column was fixed with a positive hexagon nut 14A serving as a positive electrode terminal. Moreover, the edge part of the negative electrode pole column was fixed with the negative electrode hexagon nut 14B used as a negative electrode terminal.

After ultrasonically welding the battery lid 13A to the opening of the battery can, the lithium salt solution of the ionic liquid used in Example 1 was poured from a liquid inlet (not shown) provided in the battery lid 13A. Were screwed to obtain a prismatic lithium ion secondary battery body 13 having a battery capacity of 40 Ah.

The prismatic lithium ion secondary battery with improved heat insulation properties shown in FIG. 4 was obtained by pasting the heat insulating material 15 on the bottom and side surfaces of the prismatic lithium ion secondary battery body 13. In this embodiment, the heat insulating material 15 is composed of a core material composed of a laminated body of glass wool, a heat-sealing layer containing the core material and evacuating the inside, and a film formed with a gas barrier film. It is a vacuum heat insulating material comprised from the exterior material of the double wall structure which consists of a laminate film which has the gas barrier layer combined above.

Using this prismatic lithium ion secondary battery, a charge / discharge test was conducted by a termination condition of 4.2 V, a constant current constant voltage charge for 5 hours, and a constant current discharge of a termination condition of 3.0 V.

<Example 5>
A square lithium ion secondary battery main body 13 was produced in the same manner as in Example 4 (FIG. 5). The main part of the prismatic lithium ion secondary battery body 13 was accommodated in a prismatic heat medium circulation container 17 shown in FIG.

The rectangular heat medium circulation container 17 includes a cylindrical peripheral wall portion 17 A that faces the side wall portion of the square lithium ion secondary battery body 13, and a bottom wall that faces the bottom wall portion of the square lithium ion secondary battery body 13. Part 17B. The peripheral wall portion 17A and the bottom wall portion 17B have a stainless steel double wall structure facing each other with an interval so as to form the heat medium circulation path 17 therebetween. The heat medium circuit in the peripheral wall portion 17A and the heat medium circuit in the bottom wall portion 17B communicate with each other. The peripheral wall portion 17A is provided with a heat medium inlet port and an outlet port. The heat medium introduction hose 7 is connected to the inlet port, and the heat medium discharge hose 9 is connected to the outlet port.

The heat medium is composed of water or silicone oil, heated to 50 to 70 ° C. by an external heat source, and introduced from the heat medium introduction hose 7 into the heat medium circulation path inside the square heat medium circulation container 17. Then, it circulates in the square heat medium circulation container 17 and is discharged from the heat medium discharge hose 9. Also in the present embodiment, a temperature sensor for measuring the temperature of the battery can is disposed in the square heat medium circulation container 17.

The heat medium is circulated by the square heat medium circulation container 17 so that the temperature of the accommodated prismatic lithium ion secondary battery main body 13 is 50 ° C. or higher, and the end condition of 4.2 V, as in Example 4, A charge / discharge test was conducted by constant current constant voltage charge for 5 hours and constant current discharge at a termination condition of 3.0 V.

<Example 6>
A prismatic lithium ion secondary battery body 13 was produced in the same manner as in Example 4 (FIG. 6). In this example, a sheet-like heater 11 was wound around the outer wall surface of the prismatic lithium ion secondary battery body 13 as a heating means. A heat insulating material 15 'having the same structure as that of the heat insulating material 15 used in Example 4 is bonded to the bottom and side surfaces of the prismatic lithium ion secondary battery body 13 around which the heater 11 is wound to enhance the heat insulating property shown in FIG. A rectangular lithium ion secondary battery was obtained. Using this prismatic lithium ion secondary battery, a charge / discharge test was conducted in the same manner as in Example 4 by a termination condition of 4.2 V, a constant current constant voltage charge of 5 hours, and a constant current discharge of a termination condition of 3.0 V.

<Comparative example 2>
The prismatic lithium ion secondary battery body 13 produced in the same manner as in Example 4 was subjected to a termination condition of 4.2 V, 5 hours of constant current and constant voltage and termination conditions as in Example 1 without imparting heat retention. A charge / discharge test using a constant current discharge of 3.0 V was performed.

Next, a comparative experiment was conducted on a laminated lithium ion secondary battery.

<Example 7>
A plurality of positive electrode plates and a plurality of negative electrode plates made of the same material as in Example 1 are alternately stacked via separators of the same material as the separator used in Example 1, and the current collector of the positive electrode plate A metal plate made of aluminum or an aluminum alloy serving as a positive electrode terminal and a metal plate made of copper or a copper alloy serving as a negative electrode terminal were ultrasonically welded to a current collecting portion of the negative electrode plate to form an electrode plate group. This electrode plate group was covered with a packaging material 19 made of an aluminum laminate film made of a resin sheet which is an adhesive portion with aluminum, and the lithium salt solution of the ionic liquid used in Example 1 was injected into the packaging material 19. When packaging the electrode plate group with the packaging material 19, the ear portion 20 A of the positive electrode plate and the ear portion 20 B of the negative electrode plate are exposed to the outside of the packaging material 19. Thereafter, the inside of the packaging material 19 was vacuum depressurized and sealed at a high temperature to obtain a 40 Ah laminated lithium ion secondary battery body 21.

In the same manner as in Example 4, the heat insulating material 15 was bonded to the bottom and side surfaces of the laminate type lithium ion secondary battery main body 21 to obtain a laminate type lithium ion secondary battery having improved heat insulation properties as shown in FIG. Using this laminate type lithium ion secondary battery, a charge / discharge test was conducted by a constant current and constant voltage charge at a termination condition of 4.2 V, a constant current of 5 hours, and a constant current discharge at a termination condition of 3.0 V.

<Example 8>
A laminated lithium ion secondary battery main body 21 was produced in the same manner as in Example 7 (FIG. 8). The main part of the laminate-type lithium ion secondary battery main body 21 is housed in the square-shaped heat medium circulation container 17 shown in Example 5 to obtain a laminate-type lithium ion secondary battery with improved heat insulation. Using this laminate type lithium ion secondary battery, in the same manner as in Example 7, a charge / discharge test was conducted with a termination condition of 4.2 V, a constant current constant voltage charge of 5 hours, and a constant current discharge of a termination condition of 3.0 V. It was.

<Example 9>
A laminate type lithium ion secondary battery main body 21 was produced in the same manner as in Example 7 (FIG. 9). A sheet-like heater 11 was wound around the outer wall surface of the laminate type lithium ion secondary battery main body 21. A heat insulating material 15 was bonded to the bottom and side surfaces of the laminated lithium ion secondary battery main body 21 around which the heater 11 was wound in the same manner as in Example 7 to obtain a square lithium ion secondary battery with improved heat insulation. Using this prismatic lithium ion secondary battery, a charge / discharge test was conducted in the same manner as in Example 7 by a termination condition of 4.2 V, a constant current constant voltage charge of 5 hours, and a constant current discharge of a termination condition of 3.0 V.

<Comparative Example 3>
The laminated lithium ion secondary battery main body 21 produced in the same manner as in Example 7 was subjected to a termination condition of 4.2 V, 5 hours of constant current and constant voltage and termination conditions as in Example 7 without imparting heat retention. A charge / discharge test using a constant current discharge of 3.0 V was performed.

Table 1 shows the experimental results of the discharge capacity with respect to the design capacities of Examples 1 to 9 and Comparative Examples 1 to 3.

As shown in Table 1, the discharge capacity of all of the cylindrical, square, and laminate type lithium ion secondary batteries was 7 times or more compared to the case where no heat insulating effect was given. Moreover, when it heated positively, discharge capacity became 8 times or more. Moreover, when heating and heat insulation were used in combination, the discharge capacity ratio was larger than when heating alone or heat insulation alone. Further, as can be seen from Table 1, the discharge capacity ratio was particularly improved in the laminated lithium ion secondary battery.

Next, a comparative experiment was conducted on a lithium ion secondary battery module using a cylindrical lithium ion secondary battery as an assembled battery.

<Example 10>
The cylindrical lithium ion secondary battery with improved heat insulation composed of the cylindrical lithium ion secondary battery main body 1 and the cylindrical vacuum heat insulating container 3 created in Example 1 is arranged in 12 rows by 3 rows and 4 rows. Type lithium ion secondary battery module (FIG. 10). The twelve cylindrical lithium ion secondary batteries are fastened from the outside with a fastening band (not shown). A protective cover (not shown) made of a flame retardant resin is provided on the top of the module to prevent heat dissipation. Using this lithium ion secondary battery module, a charge / discharge test was conducted by a constant current and constant voltage charge at a termination condition of 4.2 V, a constant current of 5 hours and a constant current discharge at a termination condition of 3.0 V.

<Example 11>
Twelve cylindrical lithium ion secondary battery bodies 1 created in Example 1 were accommodated in a module heat medium circulation container 23 (FIG. 11) to form a lithium ion secondary battery module. The module heat medium circulation container 23 has 12 cylindrical storage portions 24 in 3 columns and 4 rows, and the main portions of the cylindrical lithium ion secondary battery main body 1 are respectively stored in the storage portions. . The module heat medium circulation container 23 may be made of stainless steel like the cylindrical heat medium circulation container 5 of the second embodiment, but may be formed of a resin molded product. In any case, a circulation path through which the heat medium can be circulated is formed inside the module heat medium circulation container 23. An inlet port and an outlet port are formed on the peripheral wall portion of the module heat medium circulation container 23, the heat medium introduction hose 7 is connected to the inlet port, and the heat medium discharge hose 9 is connected to the outlet port. Yes. Although not shown, a temperature sensor for measuring the temperature of the battery can of the cylindrical lithium ion secondary battery main body 1 accommodated in the accommodating portion 24 is disposed in the accommodating portion 24. A protective cover (not shown) made of a flame retardant resin is provided on the top of the module to prevent heat dissipation.

Further, as in the second embodiment, the heat medium is made of water or silicone oil, and is heated to 50 to 70 ° C. by an external heat source, so that the heat medium introduction hose 7 supplies the module heat medium circulation container 23. It is introduced inside, circulates in the module heat medium circulation container 23, and is discharged from the heat medium discharge hose 9.

The heat medium is circulated by the module heat medium circulation container 23 so that the temperature of the accommodated 12 cylindrical lithium ion secondary battery main bodies 1 is 50 ° C. or higher. A charge / discharge test was conducted by constant current and constant voltage charge at 2 V for 5 hours and constant current discharge at a termination condition of 3.0 V.

<Example 12>
In the same manner as in Example 3, cylindrical lithium ion housed in a stainless steel cylindrical vacuum insulation container 3 by winding a sheet-like heater 11 around the outer wall surface of the cylindrical lithium ion secondary battery body 1 prepared in Example 1 The secondary batteries were arranged in 3 columns and 4 rows and housed in a housing case 14 to form a lithium ion secondary battery module comprising 12 cylindrical lithium ion secondary batteries (FIG. 12). The storage case 14 is made of stainless steel. A protective cover (not shown) made of a flame retardant resin is provided on the top of the module to prevent heat dissipation. Using this lithium ion secondary battery module, a charge / discharge test was conducted in the same manner as in Example 10 by a termination condition of 4.2 V, a constant current constant voltage charge for 5 hours, and a constant current discharge of a termination condition of 3.0 V.

<Comparative Example 4>
The cylindrical lithium ion secondary battery main bodies 1 created in Example 1 were arranged in 3 columns and 4 rows to form a lithium ion secondary battery module having no heat retaining property composed of 12 cylindrical lithium ion secondary batteries. Using this lithium ion secondary battery module, a charge / discharge test was conducted in the same manner as in Example 10 by a termination condition of 4.2 V, a constant current constant voltage charge for 5 hours, and a constant current discharge of a termination condition of 3.0 V.

Next, a comparative experiment was conducted on a lithium ion secondary battery module using a prismatic lithium ion secondary battery as an assembled battery.

<Example 13>
Six prismatic lithium ion secondary battery bodies 13 prepared in Example 4 were arranged side by side to form an assembled battery, and this assembled battery was used as a lithium ion secondary battery module body. In the same manner as in Example 4, the heat insulating material 15 was bonded to the bottom and side surfaces of the lithium ion secondary battery module main body made of this assembled battery to form a lithium ion secondary battery module made of a square lithium ion secondary battery. (FIG. 13). Also in this module, the positive hex nut 14A and the negative hex nut 14B are exposed.

Using this lithium ion secondary battery module, a charge / discharge test was conducted with a termination condition of 4.2 V, a constant current constant voltage charge for 5 hours, and a constant current discharge of a termination condition of 3.0 V.

<Example 14>
The lithium ion secondary battery module body made of the assembled battery prepared in Example 13 was housed in the module heat medium circulation container 25 to form a lithium ion secondary battery module (FIG. 14). The module heat medium circulation container 25 includes a cylindrical peripheral wall portion 25A facing the side wall portion of the lithium ion secondary battery module main body, and a bottom wall portion 25B facing the bottom wall portion of the lithium ion secondary battery module main body. Have. The peripheral wall portion 25A and the bottom wall portion 25B are configured by double walls facing each other so as to form a heat medium circulation path therein, and the heat medium circulation path in the peripheral wall portion 25A and the heat in the bottom wall portion 25B. The medium circuit is in communication. As a result, a circulation path through which the heat medium can be circulated is formed inside the module heat medium circulation container 25. Further, a temperature sensor (not shown) is accommodated inside the module heat medium circulation container 25. A protective cover (not shown) made of a flame retardant resin is provided on the top of the module to prevent heat dissipation. The module heat medium circulation container 25 may be formed of stainless steel or a resin material. Further, as in the fifth embodiment, the heat medium is made of water or silicone oil, and is heated to 50 to 70 ° C. by an external heat source, so that the heat medium introduction hose 7 supplies the module heat medium circulation container 25. It is introduced inside, circulates in the module heat medium circulation container 25, and is discharged from the heat medium discharge hose 9.

The heat medium is circulated by the module heat medium circulation container 25 so that the temperature of the accommodated lithium ion secondary battery module main body is 50 ° C. or higher, and the end condition is 4.2 V for 5 hours as in Example 13. The charge / discharge test was conducted by constant current constant voltage charge and constant current discharge at a termination condition of 3.0V.

<Example 15>
As in Example 6, six prismatic lithium ion secondary battery bodies 13 each having a sheet-like heater 11 wound around an outer wall surface are arranged side by side to form an assembled battery, and this assembled battery is made into a lithium ion secondary battery module. The main body. A heat insulating material 15 was bonded to the bottom and side surfaces of the lithium ion secondary battery module main body to obtain a lithium ion secondary battery module made of a square lithium ion secondary battery (FIG. 15). Also in this example, the positive hexagon nut 14A and the negative hexagon nut 14B of each square lithium ion secondary battery body 13 are exposed. A protective cover (not shown) made of a flame retardant resin is provided on the top of the module to prevent heat dissipation.

<Comparative Example 5>
A plurality of prismatic lithium ion secondary battery bodies 13 created in Example 4 were arranged to form a lithium ion secondary battery module that did not have heat retention. Using this lithium ion secondary battery module, a charge / discharge test was conducted by a constant current and constant voltage charge at a termination condition of 4.2 V for 5 hours and a constant current discharge at a termination condition of 3.0 V.

Next, a comparative experiment was conducted on a lithium ion secondary battery module using a laminated lithium ion secondary battery as an assembled battery.

<Example 16>
Five laminated lithium ion secondary battery bodies 21 prepared in Example 7 were arranged to make an assembled battery, and this assembled battery was used as a lithium ion secondary battery module body. In the same manner as in Example 13, the heat insulating material 15 was bonded to the bottom and side surfaces of the lithium ion secondary battery module body made of this assembled battery to form a lithium ion secondary battery module made of a laminated lithium ion secondary battery. (FIG. 16). Even in this module, the ears 20 A and 20 B constituting the terminal of the laminated lithium ion secondary battery main body 21 are exposed without being covered with the heat insulating material 15.

<Example 17>
The laminate-type lithium ion secondary battery module body made of the assembled battery prepared in Example 16 was accommodated in the module heat medium circulation container 25 of Example 14 to obtain a lithium ion secondary battery module (FIG. 17). A protective cover (not shown) made of a flame retardant resin is provided on the top of the module to prevent heat dissipation.

The heat medium is circulated by the module heat medium circulation container 25 so that the temperature of the accommodated lithium ion secondary battery module main body is 50 ° C. or higher, and the end condition is 4.2 V for 5 hours as in Example 16. The charge / discharge test was conducted by constant current constant voltage charge and constant current discharge at a termination condition of 3.0V.

<Example 18>
Similarly to Example 9, five laminated lithium ion secondary battery bodies 21 each having a sheet-like heater 11 wound around the outer peripheral surface of the packaging material 19 were arranged side by side to form a lithium ion secondary battery module body. A heat insulating material 15 was bonded to the bottom and side surfaces of the lithium ion secondary battery module main body to obtain a lithium ion secondary battery module made of a laminated lithium ion secondary battery (FIG. 18). A protective cover (not shown) made of a flame retardant resin is provided on the top of the module to prevent heat dissipation. Using this lithium ion secondary battery module, a charge / discharge test was conducted by a constant current and constant voltage charge at a termination condition of 4.2 V for 5 hours and a constant current discharge at a termination condition of 3.0 V.

<Comparative Example 6>
A plurality of laminated lithium ion secondary battery bodies 21 prepared in Example 7 were arranged to form a lithium ion secondary battery module that did not have heat retention. Using this lithium ion secondary battery module, a charge / discharge test was conducted by a constant current and constant voltage charge at a termination condition of 4.2 V for 5 hours and a constant current discharge at a termination condition of 3.0 V.

As shown in Table 2, in all of the cylindrical, square, and laminate type lithium ion secondary battery modules, the discharge capacity was 4 times or more compared to the case where the heat insulating effect was not given. Moreover, when it heated positively, the discharge capacity became 5 times or more. Moreover, when heating and heat insulation were used in combination, the discharge capacity ratio was larger than when heating alone or heat insulation alone. In particular, in the cylindrical type and the square type, it was possible to obtain an output almost as designed capacity. Further, as can be seen from Table 2, in the laminated lithium ion secondary battery, the discharge capacity ratio was particularly improved.

According to the present invention, a lithium ion secondary battery is constituted by a lithium ion battery main body in which an ionic liquid is injected into the battery case as an electrolytic solution, and the heat retaining means. Therefore, since the heat retaining means can keep the electrolytic solution, which is an ionic liquid, at a predetermined temperature, the viscosity of the ionic liquid is lowered, and the output of the lithium ion secondary battery using the ionic liquid can be further increased. . *

DESCRIPTION OF SYMBOLS 1 Cylindrical lithium ion secondary battery main body 2 One terminal part 3 Cylindrical vacuum heat insulation container 3A Circumferential wall part 3B Bottom wall part 4 Other terminal part 5 Cylindrical heat medium circulation container 5A Perimeter wall part 5B Bottom wall part 5C Heat medium circulation Space 7 Heat medium introduction hose 9 Heat medium discharge hose 11 Heater 13 Square lithium ion secondary battery body 13A Battery cover 14A Positive hexagon nut 14B Negative hexagon nut 15 Heat insulating material 17 Square heat medium circulation container 19 Laminate 20A Positive electrode terminal 20B Negative electrode Terminal 21 Laminated lithium ion secondary battery body 23 Heat medium circulation container for module

Claims

A lithium ion battery body in which an ionic liquid is injected as an electrolyte into the battery case;
A lithium ion secondary battery using an ionic liquid, comprising: a heat retaining means for retaining the electrolytic solution at a predetermined temperature.
The lithium ion secondary battery using an ionic liquid according to claim 1, wherein the heat retaining means is constituted by a heat insulating material covering all or a main part of the battery case of the battery body.
The lithium ion secondary battery using an ionic liquid according to claim 2, wherein the heat retaining means further includes a heating means for directly or indirectly heating the electrolytic solution.
The heat retaining means is disposed in a housing part that houses all or a main part of the battery main body, and in a wall part that surrounds the housing part or in the housing part, and is housed in the housing part. The lithium ion secondary battery using the ionic liquid according to claim 1, which is a heat medium circulation container including a circulation path through which a heat medium heated by an external heat source circulates so as to heat the battery.
An assembled battery comprising a plurality of lithium ion secondary batteries in which an ionic liquid is injected into the battery case as an electrolyte;
A lithium ion secondary battery module using an ionic liquid, comprising: a heat retaining means for keeping the electrolyte solution in the plurality of lithium ion secondary batteries at a predetermined temperature.
The lithium ion secondary battery module using an ionic liquid according to claim 5, wherein the heat retaining means is configured by a heat insulating material that covers at least a part of the assembled battery.
The lithium ion secondary battery module using an ionic liquid according to claim 6, wherein the heat retaining means further includes a plurality of heating means for respectively heating the battery cases of the plurality of lithium ion secondary batteries.
The heat retaining means includes
A housing part that accommodates all or a main part of the assembled battery, and a battery that is disposed in the housing part or in a wall portion surrounding the housing part, so as to heat the assembled battery housed in the housing part. A lithium ion secondary battery module using an ionic liquid according to claim 6, which is a heat medium circulation container comprising a circulation path through which a heat medium heated by an external heat source circulates.
A lithium ion secondary battery thermal insulation device in which an ionic liquid is injected into the battery case as an electrolyte,
The said heat retention apparatus is comprised with the heat insulating material which covers all or the principal part of the said battery case, The heat retention apparatus of the lithium ion secondary battery using the ionic liquid characterized by the above-mentioned.
The said heat retention apparatus is a heat retention apparatus of the lithium ion secondary battery of Claim 10 further equipped with the heater affixed on the outer wall surface of the battery case of the said lithium ion secondary battery, and heating the said battery case.
A lithium ion secondary battery thermal insulation device in which an ionic liquid is injected into the battery case as an electrolyte,
The heat retaining device is disposed in a housing part that accommodates all or a main part of the battery main body, and in a wall part that surrounds the housing part or in the housing part, and is housed in the housing part. A heat medium circulating container comprising a circulation path through which a heat medium heated by an external heat source circulates so as to heat the lithium ion secondary battery.
A heat retention device for a lithium ion secondary battery module that forms an assembled battery composed of a plurality of lithium ion secondary batteries in which an ionic liquid is injected into the battery case as an electrolyte,
The said heat retention apparatus is comprised with the heat insulating material which covers at least one part of the said assembled battery, The heat retention apparatus of the lithium ion secondary battery module characterized by the above-mentioned.
The lithium ion secondary battery module according to claim 12, wherein the heat retaining device further includes a plurality of heaters that are each attached to an outer wall surface of the lithium ion secondary battery to heat the lithium ion secondary battery. Insulation device.
A heat retention device for a lithium ion secondary battery module that forms an assembled battery composed of a plurality of lithium ion secondary batteries in which an ionic liquid is injected into the battery case as an electrolyte,
A housing part that accommodates all or a main part of the assembled battery, and a battery that is disposed in the housing part or in a wall portion surrounding the housing part, so as to heat the assembled battery housed in the housing part. And a heat medium circulating container comprising a circulation path through which a heat medium heated by an external heat source circulates, and a heat retaining device for a lithium ion secondary battery module.