JP4415375B2 - Non-aqueous secondary battery and manufacturing method thereof - Google Patents

Description

  The present invention relates to a non-aqueous secondary battery and a method for manufacturing the same, and more specifically, a non-aqueous battery capable of manufacturing a non-aqueous secondary battery that dislikes mixing of moisture without necessarily performing advanced humidity management (atmosphere management). The present invention relates to a secondary battery and a method for manufacturing the same.

  With the recent reduction in weight and size of electrical products, non-aqueous secondary batteries (lithium secondary batteries) having a high energy density are attracting attention and various research and development are being promoted. In addition, due to environmental problems, battery cars and hybrid cars that use electric power as part of their power have been put into practical use. Recently, in order to increase the number of models equipped with these non-aqueous secondary batteries, cost reduction is achieved. Research is actively underway.

  At present, non-aqueous secondary batteries use organic solvents that dislike moisture in the electrolyte, so the electrolyte degrades due to the chemical reaction caused by the contact between the electrolyte and moisture in the general atmosphere (air). There are quality problems such as performance degradation. To prevent this, an integrated production method from injection of electrolyte to conditioning (gas charging / discharging) and sealing of the injection port, which is the final process, is adopted in a dry room that maintains and manages a low humidity environment. ing.

However, the installation and maintenance of equipment that realizes a low humidity environment such as a dry room requires a large amount of cost. Furthermore, the size of the dry room becomes a bottleneck when increasing the production of non-aqueous secondary batteries. As described above, since the amount of capital investment for expansion of the dry room increases rapidly, there is a limit to the cost reduction in this production method.
Japanese Patent Laid-Open No. 2003-157813 Japanese Utility Model Publication No. 56-68972

  This invention is made | formed in view of the said situation, and makes it the subject which should be solved to provide the non-aqueous secondary battery which can suppress the influence on the battery by manufacturing atmosphere, and its manufacturing method.

The non-aqueous secondary battery of the present invention that solves the above problems is a non-aqueous secondary battery having a power generation element, an electrolytic solution, and a battery case including a casing portion that houses the power generation element and the electrolytic solution. ,
The battery case is integrally formed with the housing part and is formed of a heat- sealable plastic and has a communication hole for injecting the electrolytic solution into the housing part, and the electrolytic solution and / or after the electrolytic solution is injected. A check valve disposed in the communication hole and capable of discharging the gas generated from the power generation element to the outside of the casing, and the communication hole is hermetically welded after the gas is discharged. It has a mouth.
In particular, it is preferable that the check valve is disposed inside the communication hole, and the hermetically fused portion is an upper portion of the check valve.

In addition, the non-aqueous secondary battery manufacturing method of the present invention that solves the above-described problems includes a non-aqueous secondary battery having a power generation element, an electrolytic solution, and a battery case including a casing portion that houses the power generation element and the electrolytic solution. A method for manufacturing a secondary battery, comprising:
The battery case includes a liquid injection port that is integrally formed with the casing part and is formed of a heat- sealable plastic and has a communication hole that injects the electrolyte into the casing part .
A step of injecting the electrolytic solution from the liquid injection port after storing the power generation element in the casing;
The internal or the communicating electrolytic solution into the opening of the hole and / or the gas generated from the power generating element be discharged to the outside of the housing part and a check valve that will be arranged in the communicating hole of the communicating hole Providing and conditioning the power generation element and the electrolyte;
And a step of hermetically welding the communication hole.
In particular, it is preferable that the check valve is disposed inside the communication hole, and the hermetically fused portion is an upper portion of the check valve.

  In other words, by providing a check valve in the liquid injection port, it is possible to remove the gas generated inside the housing part without allowing the external gas to flow into the housing during conditioning of the non-aqueous secondary battery. it can. During conditioning of a non-aqueous secondary battery, gas is generated from the inside of the casing and the internal pressure is high, so even a simple check valve can effectively remove moisture into the casing. Inflow can be suppressed. Thereafter, the water penetration in the non-aqueous secondary battery manufactured can be effectively suppressed because the communication hole of the liquid inlet is hermetically fused. Patent Documents 1 and 2 are cited as conventional techniques. Patent Documents 1 and 2 have a structure mainly intended to improve safety during use of a battery, and are not intended to suppress moisture permeation during conditioning as in the present invention.

By integrating the said communication hole of said housing portion and the pouring hole, can be reduced is a risk of permeation of moisture.

  By adopting the configuration of the present invention, the process from injection of electrolyte into the casing, conditioning (gas venting charge / discharge), and sealing of the liquid inlet can be performed even in a general atmosphere where the dry room is eliminated. A non-aqueous secondary battery that can be produced and a method for manufacturing the same can be provided. As a result, both quality maintenance and cost reduction can be achieved.

[Non-aqueous secondary battery]
The non-aqueous secondary battery of the present invention has a battery case, a power generation element, and an electrolytic solution. The non-aqueous secondary battery of the present invention can have a known battery structure such as a coin-type battery, a button-type battery, a cylindrical battery, and a square battery. The power generation element can adopt a general configuration such as a combination of positive and negative electrodes. The electrolytic solution is a non-aqueous electrolytic solution composed of an organic solvent or the like. The battery case has a casing portion and a liquid injection port for accommodating the power generation element and the electrolyte. Hereinafter, details will be described based on a lithium secondary battery as a non-aqueous secondary battery.

The battery case includes a housing part and a liquid injection port. The casing is preferably formed of a material having low moisture permeability so that moisture does not permeate into the casing . That consists of heat-sealable-flops Rasuchi' click. The liquid injection port includes a communication hole that communicates the inside and the outside of the casing, and a check valve that restricts the movement of the fluid in the communication hole in one direction (direction from the inside of the casing to the outside). The communication hole is formed integrally with the casing. After housing the power generation element in the casing, it is desirable that the portion other than the communication hole of the liquid injection port is sealed (a gas vent hole for smoothly performing liquid injection can be provided. In this case, the gas vent hole is air-tightly fused immediately after the injection of the electrolyte. The check valve is provided after injecting the electrolyte from the communication hole into the housing. After conditioning the non-aqueous secondary battery with the check valve provided, the communication hole is hermetically sealed. The part for hermetic fusion may be any part of the communication hole. For example, the upper part of a check valve can be mentioned. In addition, since gas is not expected to flow through the communication hole after the hermetic fusion, the function of the subsequent check valve may be impaired by performing the hermetic fusion.

  The check valve can be formed, for example, by adopting a ball disposed in the communication hole. That is, on the side of the communication hole that opens to the inside of the housing portion, a throat portion that can be in close contact with the ball is formed with a diameter smaller than the outer diameter of the ball so that the ball cannot pass, and the housing is combined with the ball. A check valve that can move fluid only from the inside of the body part to the outside can be formed. Here, by adjusting the mass of the ball or providing an elastic body such as a spring that biases the ball toward the inside of the housing, it becomes possible to maintain high airtightness. Inflow of (humidity) can be suppressed. In addition, by providing a protrusion that makes the inner diameter slightly smaller than the outer diameter of the ball on the outside of the housing portion of the communication hole, it is possible to prevent the ball from jumping out from the communication structure. When the protrusion is provided only in a part of the communication hole in the circumferential direction, a gap is created between the inner wall of the communication hole and the ball except for the part that contacts the protrusion, and gas is ejected vigorously from within the housing. However, it is possible to vent the gas effectively while preventing the ball from popping out. When the protrusion is provided in the communication hole, the ball can be inserted into the communication structure irreversibly using the elastic deformation of the communication hole.

  Examples of the power generation element include an electrode body obtained by superimposing or winding a positive electrode and a negative electrode via a separator. The positive and negative current collectors are connected to the positive electrode terminal and the negative electrode terminal communicating with the outside using a current collecting lead or the like, and connected to the external terminal.

  For the positive electrode, a conductive material and a binder are mixed with a positive electrode active material capable of inserting and extracting lithium ions, and an appropriate solvent is added as necessary to form a paste-like positive electrode mixture, such as a metal such as aluminum. It is formed by applying and drying on the surface of the current collector made of foil and then increasing the active material density by pressing. As the positive electrode active material, a known positive electrode active material such as a lithium transition metal composite oxide can be used. The conductive material is for ensuring the electrical conductivity of the positive electrode, and a mixture of one or two or more carbon material powders such as carbon black, acetylene black, and graphite can be used. The binder plays a role of connecting the active material particles and the conductive material particles, and a fluororesin such as polytetrafluoroethylene, polyvinylidene fluoride, and fluororubber, and a thermoplastic resin such as polypropylene and polyethylene can be used. .

  The negative electrode is not particularly limited as long as it can use a negative electrode active material that occludes lithium ions during charging and releases lithium ions during discharging, and may be one having a known material configuration. For example, a carbon material such as lithium metal, graphite, or amorphous carbon. Among these, it is particularly preferable to use a carbon material. When a carbon material is used as the negative electrode active material, a negative electrode mixture obtained by mixing a conductive material and a binder as described for the positive electrode is applied to the current collector as necessary. It is preferable to use one.

  The electrolytic solution is obtained by dissolving an electrolyte in an organic solvent. An organic solvent will not be specifically limited if it is an organic solvent normally used for the non-aqueous electrolyte of a lithium secondary battery. For example, carbonates, halogenated hydrocarbons, ethers, ketones, nitriles, lactones, oxolane compounds and the like can be used. The type of the electrolyte is not particularly limited.

  The separator plays a role of electrically insulating the positive electrode and the negative electrode and holding the electrolytic solution. For example, a porous synthetic resin film, particularly a polyolefin polymer (polyethylene, polypropylene) porous film may be used.

[Method of manufacturing non-aqueous secondary battery]
The manufacturing method of the non-aqueous secondary battery of this invention is a method which can manufacture the non-aqueous secondary battery of this invention mentioned above. That is, the non-aqueous secondary battery to which the method of the present invention can be applied has a battery case, a power generation element, and an electrolytic solution. Each of these components is substantially the same as that described in the above-mentioned non-aqueous secondary battery column, and further description thereof is omitted.

  First, the power generation element is housed in the casing. For example, there is a method in which the power generation element is inserted from the opening of the housing and then the lid is closed. In addition to joining the lid via a seal member, when the casing is made of a metal material, a method of joining by welding can be adopted, and the casing is made of plastic (including a laminate film). In this case, a method of joining by heat fusion or the like can be employed. The method for producing the power generation element is not particularly limited. Insert the power generation element before installing a check valve in the liquid injection port.

  After the power generation element is housed in the housing, the electrolytic solution is injected through the communication hole of the liquid inlet. The electrolytic solution is held in an electrolytic solution container that is blocked from outside air, and can be taken out from the electrolytic solution outlet. By connecting the electrolyte outlet to the liquid inlet and injecting the electrolyte into the casing, it is possible to effectively suppress the electrolyte from contacting the surrounding atmosphere.

  Thereafter, a check valve is provided in the communication hole. By performing conditioning (charging / discharging under a predetermined condition) in a state where the check valve is provided, some gas is generated from the power generation element and the electrolytic solution in the casing, and is discharged to the outside through the communication hole. After the gas is no longer discharged from the communication hole, the communication hole is hermetically fused. Therefore, the pressure inside the casing is generally higher than the external pressure, and there is little possibility that gas (air or the like) flows into the casing from the outside. The check valve can completely block the gas flow from the outside to the inside of the housing.

  The non-aqueous secondary battery and the manufacturing method thereof according to the present invention will be described in detail below.

  Configuration: As shown in FIG. 1, the non-aqueous secondary battery of this example includes a power generation element 1 configured by winding a positive and negative electrode and a separator, and a positive electrode 3 and a negative electrode 4 that extract power from the power generation element 1 to the outside. And a battery case (2, 5 to 10).

  The battery case includes a housing part in which the housing body 2 and the lid 5 are joined by a welded part 5a, a liquid injection port including the communication hole 7 and the ball 8, and the communication hole 7 being hermetically fused, a safety valve The smoke exhaust port 9 sealed at 10 is provided. The safety valve 10 is a member that includes a thin-walled portion that is provided in a streak shape so as to be broken at a predetermined pressure in the lid 5 and that opens when the internal pressure of the housing portion exceeds a predetermined pressure. The ball 8 is inserted into the communication hole 7 after injecting the electrolyte into the housing through the communication hole 7. The ball 8 constitutes a check valve in combination with the communication hole 7 (particularly the throat portion 7b). That is, the communication hole 7 has a diameter of a portion (the throat portion 7b) that extends from the portion holding the ball 8 toward the inside of the battery case. When the gas flows in from the outside, the ball 8 is in close contact with the portion where the diameter is small, thereby preventing the gas from flowing in. The material of the ball 8 is desirably a material having high corrosion resistance and low moisture permeability, such as a metal subjected to corrosion resistance or a liquid crystal polymer resin having low moisture permeability. The liquid injection port, the smoke exhaust port 9 and the safety valve 10 are integrated with the lid 5 by a resin molded body 6. The safety valve 10 is a member that opens the smoke outlet 9 and discharges the internal pressure to the outside through the smoke outlet 9 when the internal pressure rises for some reason.

  Manufacturing method: A power generating element is manufactured by laminating and winding positive and negative electrodes through a separator. The power generation element is wound in a flat shape (elliptical shape), and the positive electrode terminal 3 and the negative electrode terminal 4 are welded at both ends thereof. The positive electrode terminal 3 and the negative electrode terminal 4 are integrally formed with a lid 5 by resin molding. In addition, the lid 5 is integrally formed with a communication hole 7 and a smoke exhaust port 9 by resin molding. That is, the power generation element 1 is integrated with the positive and negative electrodes 3 and 4, the lid 5 and the like.

  The power generating element 1 is inserted into the housing main body 2 together with the integrated positive and negative electrodes 3 and 4 and the lid 5. After the insertion, the contact portion between the housing body 2 and the lid 5 is welded to form a welded portion 5a that is hermetically welded.

  Thereafter, an electrolytic solution is injected into the casing from the communication hole 7 formed in the lid 5. After injecting the electrolytic solution, the ball 8 is inserted into the communication hole 7 as shown in FIG. The ball 8 is formed in the communication hole 7 and abuts against a throat portion 7 b having an inner diameter smaller than the outer diameter of the ball 8 to ensure airtightness. Since the inner diameter of the communication hole 7 is larger than the outer diameter of the ball 8, the ball 8 is easily inserted into the communication hole 7, but it does not touch the throat portion 7 b whose inner diameter is smaller than the outer diameter of the ball 8. Close contact. A spring 11 that biases the ball 8 inward is attached to the outside of the ball 8. Although not shown in the drawing, the end of the spring 11 (the side opposite to the ball 8) is locked to a jig disposed near the opening outside the communication hole 7. As a result, the ball 8 is always urged by the spring 11. When the pressure applied to the ball 8 from the inside of the housing part becomes larger than the urging force of the spring 11, the ball 8 slightly moves to the outside of the communication hole, so that a clearance is generated between the communication hole 7 and the clearance from the clearance. The internal pressure can be released to the outside.

  Conditioning is performed by repeatedly charging and discharging the power generation element 1 under predetermined conditions. During conditioning, gas is generated from the electrolyte and the power generation element 1. When the generated gas is accumulated in the casing to a predetermined pressure or more, the ball 8 can be moved against the bias of the spring 11 and the gas is extracted along the flow 12 from the gap generated in the communication hole 7. (FIG. 3). After conditioning is completed, the spring 11 is extracted from the communication hole 7 by removing the jig. Since conditioning is completed, no gas is generated from the inside of the casing. Therefore, the ball 8 stays in the communication hole 7 and blocks between the inside of the housing and the outside by its own weight. Thereafter, the communication hole 7 (upper part of the ball 8) is hermetically fused by heat to ensure the hermeticity in the casing (FIG. 4).

  Since the inside of the housing part can always be higher than the external pressure, it is possible to prevent moisture from entering the housing part without strictly adjusting the surrounding atmosphere. Accordingly, capital investment in a dry room can be suppressed, and the manufacturing cost of the non-aqueous secondary battery can be reduced.

Modified example

  When the amount of gas generated per unit time during conditioning is small, the spring 11 in the embodiment can be omitted (FIG. 5). The ball 8 can remain in the communication hole 7 due to its own weight even by gas from inside the casing (FIG. 6). After the conditioning, the communication hole 7 is hermetically fused (same as in FIG. 4).

  Moreover, it can replace with the ball | bowl 8 and the valve body 13 is employable (FIG. 7). The valve body has a hemispherical contact portion with the throat portion 7b, and is fitted into one end portion of the spring 11 on the opposite side. The other end of the spring 11 is fixed by a jig 14. After conditioning, only the spring 11 can be removed, but the communication hole 7 can also be hermetically fused with the valve body 13 removed together with the spring 11 (FIG. 8). It is possible to satisfactorily suppress the intrusion of moisture into the housing portion by quickly and hermetically fusing the communication hole 7 after taking out the valve body 13.

It is a schematic sectional drawing of the non-aqueous secondary battery of a present Example. It is the schematic of the communication hole vicinity of the non-aqueous secondary battery of a present Example (before conditioning). It is the schematic of the communicating hole vicinity of the non-aqueous secondary battery of a present Example (during conditioning). It is the schematic of the communicating hole vicinity of the non-aqueous secondary battery of a present Example (after airtightly fusing a communicating hole). It is the schematic of the communicating hole vicinity of the non-aqueous secondary battery of this modification (before conditioning). It is the schematic of the communication hole vicinity of the non-aqueous secondary battery of this modification (during conditioning). It is the schematic of the communicating hole vicinity of the non-aqueous secondary battery of this modification (before conditioning and during conditioning). It is the schematic of the communicating hole vicinity of the nonaqueous secondary battery of this modification (after airtightly fusing the communicating hole).

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 ... Electric power generation element 2 ... Housing | casing main-body part 3 ... Positive electrode terminal 4 ... Negative electrode terminal 5 ... Lid 5a ... Welding part 6 ... Resin molding 7 ... Communication hole 7a ... Airtight fusion part 7b ... Node part 8 ... Ball 9 ... Exhaust Smoke 10 ... Safety valve 11 ... Spring 13 ... Valve body

Claims (4)

A non-aqueous secondary battery having a power generation element, an electrolytic solution, and a battery case including a casing portion that houses the power generation element and the electrolytic solution,
The battery case is integrally formed with the housing part and is formed of a heat- sealable plastic and has a communication hole for injecting the electrolytic solution into the housing part, and the electrolytic solution and / or after the electrolytic solution is injected. A check valve disposed in the communication hole and capable of discharging the gas generated from the power generation element to the outside of the casing, and the communication hole is hermetically welded after the gas is discharged. A non-aqueous secondary battery having a mouth.   The check valve is disposed inside the communication hole,
  The non-aqueous secondary battery according to claim 1, wherein the hermetically fused portion is an upper portion of the check valve. A method for producing a non-aqueous secondary battery having a power generation element, an electrolytic solution, and a battery case including a casing portion that houses the power generation element and the electrolytic solution,
The battery case includes a liquid injection port that is integrally formed with the casing part and is formed of a heat- sealable plastic and has a communication hole that injects the electrolyte into the casing part .
A step of injecting the electrolytic solution from the liquid injection port after storing the power generation element in the casing;
The internal or the communicating electrolytic solution into the opening of the hole and / or the gas generated from the power generating element be discharged to the outside of the housing part and a check valve that will be arranged in the communicating hole of the communicating hole Providing and conditioning the power generation element and the electrolyte;
And a step of hermetically welding the communication holes. A method for producing a non-aqueous secondary battery.   The check valve is disposed inside the communication hole,
  The method for manufacturing a non-aqueous secondary battery according to claim 3, wherein the hermetically fused part is an upper part of the check valve.

Images