JP2017004917A - Sealed battery - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a sealed battery that can suppress internal pressure in a housing case and suppress temperature increase in the housing case when internal short-circuiting occurs in an electrode body.SOLUTION: A sealed battery includes a housing case 2, and an electrode body 3 and electrolytic solution which are housed in the housing case 2, a first safety valve 12 which is provided in the housing case 2 and causes the inside of the housing case 2 and the outside of the housing case 2 to intercommunicate with each other when the pressure in the housing case 2 exceeds a predetermined pressure, and second safety valves 14, 15 which are provided in the housing case 2 and cause the inside of the housing case 2 and the outside of the housing case 2 to intercommunicate with each other when the temperature inside the housing case 2 exceeds a predetermined temperature. When internal short-circuit occurs in the electrode body 3, the predetermined temperature is higher than the temperature inside the housing case 2 when the internal pressure inside the housing case 2 reaches a predetermined pressure at which the first safety valve 12 opens.SELECTED DRAWING: Figure 1

Description

  The present invention relates to a sealed battery.

  The sealed battery includes a housing case, an electrode body and an electrolytic solution housed in the housing case, and a safety valve is provided in the housing case to prevent the internal pressure in the housing case from becoming excessively high. It has been.

  When an internal short circuit occurs in the electrode body, a large current flows through the short circuit portion. When a large short-circuit current flows, the battery temperature rises. When the battery temperature rises, a decomposition heat reaction occurs in the electrolyte solution contacting the positive electrode and the negative electrode surface, or an exothermic decomposition reaction of the electrolyte solution itself occurs. When such a reaction occurs, the internal pressure in the housing case increases due to evaporation and decomposition of the electrolytic solution.

  The safety valve communicates between the inside of the housing case and the outside of the housing case when the internal pressure in the housing case reaches a predetermined value or more. The inside and outside of the storage case communicate with each other through a safety valve, so that the high-temperature gas in the storage case is discharged to the outside.

  For example, a non-aqueous electrolyte secondary battery described in Japanese Patent Application Laid-Open No. 2003-59476 includes an outer can, an electrode body and an electrolyte provided in the outer can, a first safety valve and a first electrode provided in the outer can. Two safety valves are provided. The pressure resistance strength of the first safety valve is set to be lower than the pressure strength of the second safety valve.

  The secondary battery described in JP2013-235831A includes an electrode assembly and a short circuit derivative. When the secondary battery penetrates the nail, the short circuit derivative diversifies the flow of the short circuit current and suppresses the generation of heat generation.

JP 2003-59476 A JP 2013-235831 A

  In the sealed battery described in Japanese Patent Application Laid-Open No. 2003-59476, when the first safety valve is opened, the pressure in the outer can is reduced, and the second safety valve is hardly opened. In addition, when the gas in the outer can is discharged to the outside in a state where the first safety valve is opened and the second safety valve is not opened, for example, a part of the scattered electrode body is clogged in the first safety valve, There is a possibility that heat dissipation may deteriorate.

  The present invention has been made in view of the above-described problems, and its purpose is to suppress the internal pressure in the storage case when an internal short circuit occurs in the electrode body, It is providing the sealed battery which can suppress the temperature rise of.

  The sealed battery is provided in the housing case, the electrode body and the electrolyte solution housed in the housing case, and the housing case. When the pressure in the housing case exceeds a predetermined pressure, the inside of the housing case and the outside of the housing case are separated. A first safety valve to be communicated, and a second safety valve that is provided in the housing case and communicates with the outside of the housing case when the temperature in the housing case exceeds a predetermined temperature. When an internal short circuit occurs in the electrode body, the predetermined temperature is higher than the temperature in the storage case when the internal pressure in the storage case reaches the predetermined pressure at which the first safety valve opens.

  According to the above configuration, when an internal short circuit occurs in the electrode body and the internal pressure and temperature in the storage case rise, the first safety valve is stored at a pressure at which the first safety valve opens before reaching the predetermined temperature at which the second safety valve opens. The internal pressure in the case reaches. Then, the first safety valve is opened. For example, when the first safety valve is opened, a part of the electrode body is scattered, the first safety valve is clogged, and the temperature in the housing case may continue to rise even when the first safety valve is opened. . Even if the first safety valve is opened, if the temperature in the storage case continues to rise, the second safety valve is then opened when the temperature in the storage case rises to a predetermined temperature. Thereby, the air permeability in a storage case improves further, and it can aim at suppression of the temperature rise in a storage case.

  According to the sealed battery of the present invention, when an internal short circuit occurs in the electrode body, it is possible to suppress an increase in pressure in the housing case and to suppress an increase in temperature in the housing case. Can do.

1 is a perspective view showing a sealed battery 1. FIG. FIG. 3 is a cross-sectional view of the sealed battery 1 and is a cross-sectional view in a state where a part of the electrode body 3 is broken. It is a graph which shows typically an internal pressure change in storage case 2 when an internal short circuit arises in electrode body 3 like a nail penetration test. It is a graph which shows typically the temperature change in the storage case 2 when an internal short circuit generate | occur | produces in the electrode body 3 like a nail penetration test. It is sectional drawing which shows the sealed battery 1 in the state which the safety valve 12 fractured | ruptured. It is sectional drawing of the sealed battery 1 in the state which the safety valve 12,14,15 fractured | ruptured. It is a perspective view which shows 1 A of sealed batteries which concern on a comparative example. It is a perspective view which shows the sealed battery 1B which concerns on an Example.

  A sealed battery 1 according to the present embodiment will be described with reference to FIG. FIG. 1 is a perspective view showing a sealed battery 1. As shown in FIG. 1, the sealed battery 1 includes a housing case 2, an electrode body 3 and an electrolytic solution 4 housed in the housing case 2, a positive terminal 5 and a negative electrode provided on the upper surface of the housing case 2. Terminal 6 included.

The electrolytic solution 4 is an organic solvent-based electrolytic solution. As the main solvent, for example, mainly a carbonate-based organic solvent is employed, and as the electrolyte, for example, LiClO ₄ , LiPF ₆ , LiBF ₄ LiPF _6. Lithium salt such as is adopted.

  The housing case 2 includes a case body 10 formed so as to open upward, an upper lid 11 provided so as to close the opening of the case body 10, and a safety valve (first safety valve) 12 formed on the upper lid 11. And a sealing portion 13 formed on the upper lid 11 and safety valves (second safety valves) 14 and 15 provided on the side surface of the case body 10.

  The housing case 2 is made of, for example, aluminum, an aluminum alloy, stainless steel, or the like. The upper lid 11 is joined to the edge of the opening of the case body 10 by welding or the like.

  The case main body 10 includes a bottom plate 20, main surface plates 21 and main surface plates 22 arranged in the thickness direction X of the case main body 10, and side plates 23 and side plates 24 arranged in the width direction Y of the case main body 10. .

  FIG. 2 is a cross-sectional view of the sealed battery 1 and is a cross-sectional view in a state where a part of the electrode body 3 is broken. As shown in FIG. 2, the electrode body 3 is formed by winding a positive electrode sheet 25, a separator 26, a negative electrode sheet 27, and a separator 28 in a sequentially laminated state. The positive electrode core exposed portion 29 and the negative electrode core exposed portion 30 arranged in the width direction Y are included.

The positive electrode sheet 25 includes a positive electrode obtained by applying a positive electrode material such as a positive electrode active material to a metal foil, and a metal exposed portion where the metal foil is exposed without applying the positive electrode material. As the positive electrode active material, for example, a lithium insertion compound such as LiCoO ₂ , LiNiO ₂ , LiMn ₂ O ₄ or the like is employed. The metal exposed portion is formed on one side of the positive electrode sheet 25, and the positive electrode core exposed portion 29 is formed by winding the metal exposed portion.

  The negative electrode sheet 27 includes a negative electrode obtained by applying a negative electrode material such as a negative electrode active material to a metal foil, and a metal exposed portion where the metal foil is exposed without applying the negative electrode material. The metal exposed portion is formed on one side of the negative electrode sheet 27, and the negative electrode core exposed portion 30 is formed by winding the metal exposed portion. As the negative electrode active material, a graphite-based material or the like is employed.

  The positive electrode terminal 5 includes a terminal portion 35, a connection member 36 having one end connected to the terminal portion 35, a current collector 37 connected to the other end of the connection member 36 and connected to the positive electrode core exposed portion 29. And an insulating member 38. The insulating member 38 ensures insulation between the terminal portion 35, the connecting member 36, the current collector 37, and the housing case 2.

  The negative electrode terminal 6 includes a terminal portion 40, a connecting member 41 having one end connected to the terminal portion 40, a current collector 42 connected to the other end of the connecting member 41 and connected to the negative electrode core exposed portion 30. And an insulating member 43. The insulating member 43 ensures insulation between the terminal portion 40, the connecting member 41, the current collector 42, and the housing case 2.

  In FIG. 1, the safety valve 12 is formed to be thinner than other portions of the housing case 2, and is formed to break when the internal pressure in the housing case 2 exceeds a predetermined value.

  The safety valve 14 and the safety valve 15 are formed of a thermoplastic resin, and are softened or melted when the inside of the housing case 2 reaches a predetermined temperature or higher. The safety valve 14 and the safety valve 15 are excellent in chemical resistance against an organic solvent and are formed of a material having a heat resistant temperature of 150 ° C. or higher.

  The predetermined pressure at which the safety valve 12 is opened and the predetermined temperature at which the safety valve 14 and the safety valve 15 are opened will be described with reference to FIGS. 3 and 4. FIG. 3 is a graph schematically showing a change in internal pressure in the housing case 2 when an internal short circuit occurs in the electrode body 3 as in a nail penetration test. FIG. 4 is a graph schematically showing a temperature change in the housing case 2 when an internal short circuit occurs in the electrode body 3 as in a nail penetration test. 3 and 4, the horizontal axis indicates the elapsed time from when an internal short circuit occurs.

  In FIG. 3, “P0” indicates the pressure inside the housing case 2 when the safety valve 12 is opened. In FIG. 4, “T0” indicates the temperature inside the housing case 2 when the safety valve 14 and the safety valve 15 are melted. As shown in FIGS. 3 and 4, when an internal short circuit occurs in the electrode body 3 by the nail penetration test, the internal pressure in the housing case 2 increases. At time t1, the internal pressure in the storage case 2 reaches the pressure P0, the safety valve 12 is opened, and the inside of the storage case 2 communicates with the outside of the storage case 2. Thereby, after time t1, the increase in the internal pressure in the storage case 2 is suppressed. The temperature in the housing case 2 at time t1 is the temperature T1, and the temperature T1 is lower than the temperature T0.

  In the example shown in FIG. 4, the temperature in the storage case 2 rises even after the time t1. When the temperature in the housing case 2 reaches the temperature T0, the safety valve 14 and the safety valve 15 are melted. Thus, when an internal short circuit occurs in the electrode body 3, the safety valve 12 is opened before the safety valve 14 and the safety valve 15, and thereafter the safety valve 12 and the safety valve 15 are opened. Is set to a valve opening pressure at which the safety valves 14 and 15 are melted.

  In the sealed battery 1 configured as described above, the operation and effect of the safety valve 12 and the safety valves 14 and 15 when an internal short circuit occurs in the electrode body 3 as in a nail penetration test or the like will be described.

  When an internal short circuit occurs in the electrode body 3, a large short circuit current flows between the positive electrode of the positive electrode sheet 25 and the negative electrode of the negative electrode sheet 27. When a short-circuit current flows between the positive electrode and the negative electrode, the battery reaction proceeds rapidly and gas is generated in the housing case 2. Thereby, the internal pressure in the storage case 2 rises. In addition, the electrolytic solution decomposes on the surface of each active material, or the active material in each electrode generates heat, so that the temperature in the housing case 2 rises.

  When the internal pressure in the storage case 2 becomes a predetermined value or more, as shown in FIG. 5, the safety valve 12 is broken and the inside of the storage case 2 communicates with the outside of the storage case 2 so that the gas in the storage case 2 is external. To be discharged. Here, when the gas is exhausted to the outside, a part of the electrode body 3 is scattered, and a part of the electrode body 3 is clogged in the opening portion of the opened safety valve 12, which may deteriorate the heat dissipation. .

  In particular, when the temperature of the positive electrode active material itself becomes very high due to a battery reaction or a short-circuit current, the thermal decomposition reaction of the positive electrode active material proceeds, and the temperature in the housing case 2 may increase. When a part of the electrode body 3 is clogged in the opening of the safety valve 12, the temperature in the housing case 2 rises.

  When the temperature in the housing case 2 becomes equal to or higher than a predetermined temperature, the safety valve 14 and the safety valve 15 are softened, the safety valve 14 and the safety valve 15 are broken, and the safety valve 14 and the safety valve 15 are opened as shown in FIG. By opening the safety valve 14 and the safety valve 15, the inside of the housing case 2 communicates with the outside of the housing case 2, and the heat in the housing case 2 can be radiated to the outside of the housing case 2.

  In this manner, even when the internal pressure of the storage case 2 is not high due to the safety valve 12 being opened, the safety valve 14 and the safety valve 15 can be opened when the temperature in the storage case 2 increases, and the storage case 2 The inside temperature can be prevented from becoming excessively high. For example, in the example shown in FIG. 4, the temperature in the housing case 2 is lowered after time t1.

  Next, a result of performing a nail penetration test using the sealed battery according to the comparative example and the sealed battery according to the example will be described.

  The nail penetration test was performed in a state where each sealed battery 1 was in a charged state of SOC 80% under a temperature environment of 25 ° C. Specifically, an iron nail having a diameter of 6 mm and a tip sharpness of 30 ° was pierced perpendicularly at a speed of 20 mm / sec and penetrated in the vicinity of the center of the main surface plate 21 of the housing case.

  FIG. 7 is a perspective view showing a sealed battery 1A according to a comparative example. As shown in FIG. 7, the sealed battery 1A includes a safety valve 12A formed on the upper lid 11A. On the other hand, the sealed battery 1A does not include safety valves formed on the side plates 23A and 24A.

  FIG. 8 is a perspective view showing a sealed battery 1B according to the embodiment. As shown in FIG. 8, sealed battery 1B includes safety valve 12B formed on upper lid 11B and safety valves 14B and 15B formed on side plates 23B and 24B.

  Here, the area ratio between the safety valve area of the safety valve 12A of the sealed battery 1A and the total safety valve area of the safety valve 12B, safety valve 14B, and safety valve 15B of the sealed battery 1B is the safety valve area of the safety valve 12A. Assuming 1, the total safety valve area of the safety valve 12B, the safety valve 14B, and the safety valve 15B is 1.40.

  The above-described nail penetration test was performed on the sealed battery 1A and the sealed battery 1B configured as described above. The following table shows the maximum temperature reached by the sealed battery 1A and the sealed battery 1B during the nail penetration test.

  As shown in Table 1 above, it can be seen that the maximum reached temperature of the sealed battery 1B according to the example is about 200 ° C. lower than the maximum reached temperature of the sealed battery 1B according to the comparative example.

  In the above-described embodiments and examples, examples where the sealed battery is applied to a lithium ion battery have been described. However, the present invention is not limited to a lithium ion battery, and can be applied to other sealed batteries.

  Although the embodiments and examples based on the present invention have been described, the matters disclosed this time are examples in all respects and are not restrictive. The technical scope of the present invention is defined by the terms of the claims, and is intended to include any modifications within the scope and meaning equivalent to the terms of the claims.

  The present invention can be applied to a sealed battery.

  1, 1A, 1B sealed battery, 2 housing case, 3 electrode body, 4 electrolyte, 5 positive terminal, 6 negative terminal, 10 case body, 11, 11A, 11B upper lid, 12, 12A, 12B, 14, 14B, 15, 15B Safety valve, 13 Sealing part, 20 Bottom plate, 21, 22 Main face plate, 23, 23A, 23B, 24, 24A, 24B Side plate, 25 Positive electrode sheet, 26, 28 Separator, 27 Negative electrode sheet, 29 Positive electrode core Body exposed portion, 30 Negative electrode core exposed portion, 35, 40 Terminal portion, 36, 41 Connection member, 37, 42 Current collector, 38, 43 Insulating member, X thickness direction, Y width direction.

Claims (1)

A containment case;
An electrode body and an electrolytic solution housed in the housing case,
A first safety valve that is provided in the storage case and communicates with the outside of the storage case when the pressure in the storage case exceeds a predetermined pressure;
A second safety valve provided in the housing case, wherein the second safety valve communicates the inside of the housing case with the outside of the housing case when the temperature in the housing case exceeds a predetermined temperature;
With
When an internal short circuit occurs in the electrode body, the predetermined temperature is higher than the temperature in the storage case when the internal pressure in the storage case reaches the predetermined pressure at which the first safety valve opens. High, sealed battery.

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