JPH09190838A - Lithium ion secondary battery - Google Patents

Abstract

(57) 【Abstract】 PROBLEM TO BE SOLVED: To prevent the influence of an internal short circuit of a large-capacity lithium-ion secondary battery from spreading to adjacent positive and negative electrodes, and to minimize the damage of the battery itself and its influence on the surroundings. The purpose is to keep it to the limit. A separator 8 includes a positive electrode 2 having a positive electrode current collector 5 coated with a positive electrode active material 4 on one side or both sides, and a negative electrode 3 having a negative electrode current collector 7 coated with a negative electrode active material 6 on one side or both sides. In the lithium-ion secondary battery laminated via, an interface 25 where the positive electrode 2 and the negative electrode 3 do not face each other is provided, and a heat-resistant heat-resistant layer 26 of a metal oxide glass layer having electrolytic solution resistance is provided on the interface 25. Intervening.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a large capacity lithium ion secondary battery suitable for use in, for example, electric vehicles, UPS (uninterruptible power supply), load leveling and the like.

[0002]

2. Description of the Related Art Conventionally, lithium-ion secondary batteries have been researched and developed in many fields related to environmental problems such as electric vehicles, UPS, load leveling, and have large capacity, high output, high voltage, and long-term storability. What is excellent is required.

In this lithium ion secondary battery, during charging, lithium is dissolved out of the positive electrode active material of the positive electrode as lithium ions into the electrolytic solution in the separator and enters the negative electrode active material of the negative electrode, and during discharge, this Lithium ions that have entered the negative electrode active material of the negative electrode are released into the electrolytic solution, and return to the positive electrode active material of the positive electrode to perform the charging / discharging operation.

In order to increase the energy density of a conventional small lithium ion secondary battery, an active material is applied to both the front and back surfaces of a metal foil current collector to form sheet-shaped positive and negative electrodes, and a polyethylene or polypropylene electrode is used. In most cases, this is a prismatic battery in which a large number of electrode pairs of a predetermined size are sequentially laminated with a separator, or a cylindrical battery structure in which long positive and negative electrodes are wound with a polyethylene or polypropylene separator. It was

[0005]

A large-capacity lithium-ion secondary battery is formed by sequentially laminating a positive electrode and a negative electrode in which active material is applied on both sides of a current collector, similarly to the small lithium-ion secondary battery described above. When configured, due to the large capacity, if an internal short circuit occurs, that part will generate heat, and the separator between the adjacent positive and negative electrodes will heat-melt, and as a result of the expansion of the internal short circuit, a large amount of heat will be released to the surroundings. However, there is a problem that a large amount of gas may be ejected.

[0006] Generally, as a simulation test of an internal short circuit of a battery, a nail puncture test is carried out in which a nail is pierced from outside the battery to artificially short the positive and negative electrodes. The present inventor has found that, in a process in which a large-capacity lithium ion secondary battery as described above reaches a large amount of gas jetting at the time of nail sticking, heat generation due to resistance of the nail sticking portion becomes a fire, and a separator between adjacent positive and negative electrodes is Heat is melted and heat is generated by the direct reaction between the positive and negative electrodes, the separator between the next adjacent electrodes is melted by heat, sequential heat is generated, and finally large heat is generated by the reaction of all electrodes. I found it.

In view of this, the present invention prevents the influence of an internal short circuit of a large-capacity lithium ion secondary battery from spreading between adjacent positive and negative electrodes, and damages the battery itself and the surrounding environment. The purpose is to minimize the impact.

[0008]

Means for Solving the Problems The lithium-ion secondary battery of the present invention comprises a positive electrode current collector coated with a positive electrode active material on one side or both sides thereof, and a negative electrode current collector coated with a negative electrode active material on one side or both sides thereof. In a lithium ion secondary battery in which a negative electrode and a negative electrode are laminated via a separator, an interface where the positive electrode and the negative electrode do not face each other is provided, and this interface is a heat-insulating heat-resistant layer of a metal oxide glass layer having electrolytic solution resistance. Is intervening.

According to the present invention, since the positive electrode and the negative electrode are provided with an interface that does not face each other, and the heat-insulating heat-resistant layer of the metal oxide glass layer having the electrolytic solution resistance is interposed at this interface, an internal short circuit is prevented. Even if it occurs, it can be prevented from spreading to the adjacent positive and negative electrodes.

Since the metal oxide glass layer may be coated and vitrified, it can be formed at a relatively low temperature of 200 ° C. or lower.

[0011]

EXAMPLES Examples of the lithium ion secondary battery of the present invention will be described below with reference to FIGS. 1, 2 and 3.
2 and 3, reference numeral 10 denotes a flat rectangular battery case, and the flat rectangular battery case 10 has, for example, a thickness of 300 μm.
It is made of stainless steel plate of m and has a horizontal length of about 300 m.
The battery case body 10a has a length of m, a length of about 115 mm, and a thickness of about 22 mm, and an upper lid 10b made of a stainless steel plate having a thickness of 1.5 mm.

In the flat rectangular battery case 10, as shown in FIG. 1, the sheet-shaped negative electrode 3 is housed in the bag-shaped separator 8 and the sheet-shaped positive electrode 2 is housed in the bag-shaped separator 8. The electrode pair 24 sandwiched between the two positive electrode units and the laminated body 14 in which the heat insulating heat resistant layer is laminated are housed.

The positive electrode 2 is manufactured as follows. Lithium carbonate and cobalt carbonate were mixed so that Li / Co (molar ratio) = 1 and fired in air at 900 ° C. for 5 hours to synthesize a positive electrode active material (LiCoO ₂ ). This positive electrode active material was crushed using an automatic mortar, and LiCoC
_Two powders were obtained.

91% by weight of a mixture obtained by mixing 95% by weight of the LiCoO ₂ powder thus obtained and 5% by weight of lithium carbonate, 6% by weight of graphite as a conductor material, and polyfluoride as a binder. Vinylidene was mixed at a ratio of 3% by weight to obtain a positive electrode mixture, which was dispersed in N-methyl-2-pyrrolidone to form a slurry, and this positive electrode mixture slurry was used as a positive electrode current collector 5 of a strip-shaped aluminum foil. A sheet-shaped positive electrode 2 in which the positive electrode mixture 4 is applied to one surface of the positive electrode current collector 5 is formed by applying the lead portion on one surface while leaving the lead portion, drying and compression-forming with a roller press. .

Next, a heat-insulating heat-resistant layer of a metal oxide glass layer having electrolytic solution resistance is formed on the surface of the obtained positive electrode 2 on which the positive electrode mixture 4 has not been applied, as follows. The base compound and catalyst were prepared as follows.

Main agent; zirconium: tetrabutoxide:
5: 1 by weight of Zr (OBu) ₄ (in the ratio of solvent: water + methanol + ethanol + isopropanol (hereinafter H ₂ O +
Represented as MeOH + EtOH + i-PrOH) =
The mixture was mixed with a mixed solvent having a ratio of 1: 1: 1: 4, and further triethoxyborane B (oEt) ₃ was added at 0.2 mol / mol.
It was added at a rate of kg and dissolved by stirring for 10 minutes to prepare a main agent. Zr (OBu) for i-PrOH in the main agent
The concentration of ₄ is 70 (weight)% (20% as ZrO ₂ ).

Catalyst: acidic ammonium fluoride NH ₄ F.HF was used as a halogen ion source, and the F-concentration was 0.1 mol / k with respect to the total weight of the main solvent and the same mixed solvent.
g. The main agent and the catalyst prepared as described above were mixed at a weight ratio of 3: 1 and stirred for 10 minutes, and then hydrochloric acid and aqueous ammonia were used to p.
H was adjusted to 6.0 (using an ethanol solution of methyl red + bromocresol green as an indicator), aged for 3 hours, hydrolyzed and dehydrated to give a coating agent.

This coating agent has a viscosity of 18 cm.
Poise and apply this coating agent to the positive electrode current collector 5
This is applied by leaving the lead part on the uncoated surface of electrode mixture 4.
Gradually increase the temperature, especially in the temperature range of 50 to 70 ° C
And perform preliminary drying (solvent volatilization step), then 120 ° C
It was held for 30 minutes and baked to vitrify. Got this
Of oxidized metal oxide glass film and spherical fine particle layer_Twoof
The layer 26 had a thickness of 13 to 15 μm. Got this
ZrO_TwoThe physical properties of layers are based on the refractive index (Becke line method, sodium
Light source) N_D ^{twenty five}: 1.88-1.89, film quality: transparent, non-porous
Met. N_D ^{twenty five}25 on the right shoulder of means 20 ° C
Things.

The negative electrode 3 is manufactured as follows. Petroleum pitch was used as a starting material, 10 to 20% of oxygen functional groups were introduced into this (so-called oxygen cross-linking), and a non-graphitizable carbon material having properties close to those of glassy carbon fired at 1000 ° C. in an inert gas was obtained. obtain.

90% by weight of the carbon material as the negative electrode active material and 10% by weight of polyvinylidene fluoride as the binder were mixed to prepare a negative electrode mixture, and this was mixed with N-methyl-.
Dispersed in 2-pyrrolidone to form a slurry, the negative electrode active material slurry is applied to both sides of a strip-shaped copper foil that is the negative electrode current collector 7 leaving a lead portion, dried, and then compression-formed with a roller press, A sheet-shaped negative electrode 3 in which the negative electrode mixture 6 is applied to both surfaces of the negative electrode current collector 7 is prepared.

The sheet-shaped positive electrode is continuously connected to the lead portion.
Application part of the positive electrode mixture 4 and ZrO _TwoLayer 26 part size
Die cutting so that the size becomes 107 mm x 265 mm, for example
Then, the area where the positive electrode mixture 4 of the stamped positive electrode 2 is applied and
And ZrO_TwoThe layer 26 has a thickness of 25 μm and a size of 112.
mm × 273 mm polypropylene microporous film
It is housed in a bag-shaped separator 8 in which two sheets of the
Knit. In this case, the lead portion of the positive electrode 2 is
It is exposed from the separator 8.

Further, the size of the coated portion of the negative electrode mixture 6 in which the sheet-shaped negative electrode is continuous with the lead portion is, for example, 109 mm ×
The die was cut to have a thickness of 270 mm, and the portion of the die-cut negative electrode 3 coated with the negative electrode mixture 6 had a thickness of 25 μm and a size of 11
A 2 mm × 273 mm polypropylene microporous film is housed in a bag-shaped separator 8 which is bonded together to form a negative electrode unit. In this case, the lead portion of the negative electrode 3 is exposed from the separator 8.

In this example, as shown in FIG. 1, this one negative electrode unit is sandwiched from two sides by two positive electrode units so that the negative electrode mixture 6 and the positive electrode mixture 4 face each other. And, 31 pairs of this electrode pair 24 are laminated,
As shown in FIG. 3, a rectangular laminated body 14 is formed. In this case, the lead portion of the positive electrode 2 is on one side and the lead portion of the negative electrode 3 is on the other side. Further, in this case, the positive electrode 2 is opposed between the electrode pair 24 via the ZrO ₂ layer 26 and the two separators 8 as a two-layer metal oxide glass layer, and the positive and negative electrodes 2 and 3 is an interface 25 that does not face each other.

Further, as shown in FIG. 3, one side of the laminate 14, that is, the lead portion exposed from the separator 8 of the positive electrode 2 is welded to the positive electrode terminal 11 made of an aluminum prism by ultrasonic welding. The other end of the laminate 14, that is, the lead portion exposed from the separator 8 of the negative electrode 3 is welded to the negative electrode terminal 12 made of a copper prism by ultrasonic welding.

The laminated body 14 having the positive electrode terminal 11 and the negative electrode terminal 12 as shown in FIG. 3 welded thereto is covered with an insulating sheet, and is bolted to the upper lid 10b through the O-ring and the insulating ring at the lead body portion. Then, the battery case body 10
a into the battery case body 10a.
Laser welding is used to fix it.

In this case, an organic electrolytic solution in which LiPF ₆ is dissolved in a mixed solvent of propylene carbonate and diethyl carbonate at a ratio of 1 mol / 1 is injected into the flat rectangular battery case 10.

Further, a safety valve 13 is provided on the upper lid 10b for venting the gas inside the closed flat rectangular battery case 10 when the internal pressure becomes higher than a predetermined value.

According to the lithium ion secondary battery of this example, a large capacity lithium ion secondary battery having a capacity of 35 Ah can be obtained.

According to this example, an interface 25 where the positive and negative electrodes 2 and 3 do not face each other is provided for every other pair of electrodes 24, and this interface 25 is a heat-insulating heat-resistant layer having an electrolytic solution resistance and ZrO. _{Since the two} layers 26 are interposed, even if an internal short circuit occurs, it can be prevented from spreading to the adjacent electrode pair 24, and damage to the battery itself and its influence on the surroundings can be minimized. Have a profit

Incidentally, a nail penetration test was conducted on the lithium ion secondary battery of the above-mentioned example. The results of this nail penetration test are shown in Table 1 as Example 1.

[0031]

[Table 1]

The weight reduction rate in Table 1 shows the reduction rate of the electrolytic solution weight in the battery before and after the nail penetration, and the smaller the weight reduction rate, the less the gas ejection. This Example 1 has a small weight reduction rate of 18%, and even if an internal short circuit occurs, it can be prevented from spilling over to the adjacent electrode pair 24, and damage to the battery itself and influence on the surroundings can be prevented. It shows that it can be minimized.

As a comparative example 1 (conventional example) for this,
As shown in FIG. 14, in Example 1 described above, the positive electrode current collector 5
Layers of the positive electrode mixture 4 are provided on both sides of the positive electrode unit 2 in which the positive electrode 2 having no heat-insulating and heat-resistant layer is housed in the bag-shaped separator 8, and 30 and 31 units are sequentially laminated to form a laminated body 14. A lithium ion secondary battery having the same structure as in Example 1 except above and having a capacity of 34 Ah was obtained, and a nail penetration test was performed for Comparative Example 1. As shown in Table 1, the result of the nail penetration test of Comparative Example 1 shows that the weight reduction rate is large and is 1
This is 30%, which means that when an internal short circuit occurs, the generated heat spreads between the adjacent electrodes.

The ZrO ₂ layer 26, which is the heat-insulating heat-resistant layer of this example, is obtained by applying the above-mentioned coating agent and baking it at 120 ° C., so that it can be obtained by a relatively low temperature treatment and is easy to manufacture. There is.

Next, Examples 2 to 5 in Table 1 will be described.
In Example 2, as shown in FIG. 5, a heat-insulating heat-resistant layer formed on the surface of the positive electrode 2 of Example 1 on which the active material was not coated, was used as an aluminum source of aluminum isopropoxide Al.
(OP _n-1 ) ₃ is used to suppress the formation of hydroxide,
An Al ₂ O ₃ layer 27 having a thickness of 13 to 15 μm was formed according to Example 1 except that a 10% (by weight) ethanol solution of triethanolamine was added as a masking agent. The physical properties of the obtained Al ₂ O ₃ layer were: refractive index (Becke line method, sodium light source) N _D ²⁵ : 1.76, film quality: transparent, and non-porous. The Al ₂ O ₃ layer 27 is a heat insulating and heat resistant layer having electrolytic solution resistance. Other than that, the large-capacity lithium-ion secondary battery having a capacity of 35 Ah was manufactured with the same configuration as in the above-described first embodiment.

In the second embodiment, 1 of the electrode pair 24 is used.
Interface 2 where positive and negative electrodes 2 and 3 do not face each other
5 is provided, and the Al ₂ O ₃ layer 27, which is a heat-insulating and heat-resistant layer having electrolytic solution resistance, is interposed at the interface 25.
Even if an internal short circuit occurs, it is possible to prevent it from spreading to the adjacent electrode pair 24, and it is possible to minimize the damage to the battery itself and the influence on the surroundings.

By the way, when a nail penetration test was conducted on the lithium ion secondary battery of Example 2, the weight reduction rate of Example 2 was as small as 17% as shown in Table 1.

In Example 3, as shown in FIG. 6, a heat-insulating heat-resistant layer formed on the surface of the positive electrode 2 of Example 1 on which the active material was not coated was treated with tetraethoxysilane Si (O 2) as a silicon source.
Et) ₄ was used, and the thickness was 13 to 30 in accordance with Example 1.
A 15 μm SiO ₂ layer 28 was formed. SiO obtained
The physical properties of the _second layer 28 were: refractive index N _D ²⁵ : 1.36, film quality: transparent, and non-porous. The SiO ₂ layer 28 is a heat-resistant and heat-resistant layer having electrolytic solution resistance. Other than that, the large-capacity lithium-ion secondary battery having a capacity of 35 Ah was manufactured with the same configuration as in the above-described first embodiment.

In the third embodiment as well, an interface 25 between the positive and negative electrodes 2 and 3 that does not face each other is provided every other pair of the electrode pairs 24, and each of the interfaces 25 has a heat-insulating heat-resistant layer having electrolytic solution resistance. As a result, since the SiO ₂ layer 28 is interposed, even if an internal short circuit occurs, the adjacent electrode pair 24
Therefore, there is an advantage that it is possible to prevent the damage to the battery itself and to minimize the damage to the battery itself and the influence on the surroundings.

By the way, when a nail penetration test was conducted on the lithium ion secondary battery of this Example 3, the weight loss of this Example 3 was at least 19% as shown in Table 1.

In Example 4, as shown in FIG. 7, a heat-insulating heat-resistant layer formed on the surface of the positive electrode 2 of Example 1 not coated with the active material was formed as follows. 16.7-77.6
-5.7 (wt%), 4-16-1 (mol%), Si (OEt), B (OEt) ₃ , and Zn (O) as raw materials
Pr) ₂ in the above ratio, and these are H
_In a mixed solvent of ₂ O + EtOH + i-PrOH = 1: 1: 5, the ratio of the raw materials (the total amount of the above three components) to the mixed solvent is 5:
The resulting mixture was added so that the amount became 1, and the mixture was stirred and mixed for 10 minutes to prepare a main agent. The concentration of metal alkoxide in this solution is i-PrO.
70% by weight with respect to H, 20 as oxide glass
(Weight)%.

NH ₄ F.HF was used as the catalyst, and H
₂ O + EtOH + i-PrOH = 1: 1: 5 In a mixed solvent, the F-concentration was adjusted to 0.5 mol / kg. The main agent and the catalyst are mixed in a ratio of 3: 1 by weight,
After adjusting the pH to 4.5 to 5.0, the mixture was stirred for 10 minutes, thoroughly mixed, and aged for 3 hours to obtain a coating agent. This coating agent (viscosity 16 cp) is applied to the surface of the positive electrode 2 on which the active material has not been coated, and the temperature is gradually raised in the section of 50 to 70 ° C. with particular attention to predrying.
Hold at 50 ° C. for 20 to 30 minutes to complete vitrification,
A SiO ₂ —B ₂ O ₃ —ZnO multi-component glass layer 29 having a thickness of 13 to 15 μm was formed. Obtained multi-component glass layer 2
The physical properties of No. 9 were: refractive index N _D ²⁵ : 1.48, film quality: transparent, and non-porous. Otherwise, the configuration is similar to that of the first embodiment,
A large capacity lithium ion secondary battery with a capacity of 35 Ah was manufactured.

In the fourth embodiment as well, an interface 25 between the positive and negative electrodes 2 and 3 that does not face each other is provided every other pair of electrode pairs 24, and each of the interfaces 25 has a heat-insulating heat-resistant layer having electrolytic solution resistance. As SiO ₂ —B ₂ O ₃ —Zn
Since the O multi-component glass layer 29 is interposed, even if an internal short circuit occurs, it can be prevented from spreading to the adjacent electrode pair 24, and the damage of the battery itself and the influence on the surroundings can be minimized. There are benefits that can be.

By the way, when a nail penetration test was conducted on the lithium-ion secondary battery of Example 4, the weight loss of Example 4 was as small as 18% as shown in Table 1.

In Example 5, a heat-insulating heat-resistant layer of a metal oxide glass layer formed on the surface of the positive electrode 2 on which the active material was not coated was formed as shown in FIG. 10-8
0-10 (wt%), Si (OEt), Pb as raw materials
(OPr- _i ) ₂ and Al (OPr) ₃ are taken as oxides in the above proportions, and these are H ₂ O + M
In a mixed solvent of OH + EtOH + i-PrOH = 1: 1: 1: 4, the ratio of the raw material (total amount of the above three) to the mixed solvent was 5: 1 (that is, the concentration of the raw material to i-PtOH was 7: 1).
0% by weight and the amount of glass is 20% by weight), and then SiO ₂ —PbO—Al ₂ according to Example 1 below.
An O ₃ multi-component glass layer 31 was formed. The physical properties of the resulting multi-component glass layer were: refractive index N _D ²⁵ : 1.92, film quality: transparent, and non-porous. Other than that, the large-capacity lithium-ion secondary battery having a capacity of 35 Ah was manufactured with the same configuration as in the above-described first embodiment.

In the fifth embodiment as well, an interface 25 between the positive and negative electrodes 2 and 3 not facing each other is provided every other pair of the electrode pairs 24, and each of the interfaces 25 has a heat-insulating heat-resistant layer having electrolytic solution resistance. As SiO ₂ -PbO-Al ₂
Since the O ₃ multi-component glass layer 31 is interposed, even if an internal short circuit occurs, it can be prevented from spreading to the adjacent electrode pair 24, and the damage to the battery itself and the influence on the surroundings can be minimized. There are benefits that can be held down.

By the way, when a nail penetration test was conducted on the lithium-ion secondary battery of Example 5, the weight loss of Example 5 was as small as 18% as shown in Table 1.

Example 6 shows an example of a cylindrical lithium ion secondary battery. To manufacture the lithium-ion secondary battery of Example 6, first, as the positive electrode 40, in the same manner as in Example 1, the positive electrode mixture 4 was applied to one surface of the positive electrode current collector 5 having a size of 280 mm × 1745 mm. Strip-shaped positive electrode 4
In the same manner as in Example 1, a strip-shaped negative electrode electrode 41 in which the negative electrode mixture 6 was applied to both surfaces of the negative electrode current collector 7 having a size of 283 mm × 1750 mm was manufactured.
To produce. On the surface of the positive electrode 40 not coated with the positive electrode mixture, a ZrO ₂ layer having a thickness of 13 to 15 μm, which is a heat insulating and heat resistant layer having electrolytic solution resistance, is formed as in Example 1.

The thickness is 25 μm and the size is 287 mm × 1.
A separator 8 made of a 755 mm polyethylene film or polypropylene film is prepared, and as shown in FIG. 9, the positive electrode 40, the separator 8, the negative electrode 41,
The separator 8 and the positive electrode 40 are stacked in this order, and the positive electrode mixture 4 of the positive electrode 40 and the negative electrode mixture 6 of the negative electrode 41 are stacked.
Are stacked so as to face each other to form an electrode pair 43, and the electrode pair 43 is spirally wound a predetermined number of times along the longitudinal direction to form a spiral stack 44.

In this case, in the spiral laminated body 44, as shown in FIG. 9, the positive electrode 40 and the positive electrode 40 are opposed to each other with the ZrO ₂ layer 32, which is a heat-insulating and heat-resistant layer, facing each other every other electrode pair 43. Also, there is an interface 43a where the negative electrodes 40 and 41 do not face each other.

Further, as shown in FIG. 4, one end of a negative electrode lead 45 made of nickel is welded to a lead portion on one side of the negative electrode 41 by resistance welding, and a positive electrode made of aluminum is made on a lead portion on one side of the positive electrode 40. One end of the lead 46 is welded by resistance welding.

A nickel-plated iron diameter 5
A cylindrical battery can 47a having a height of 0 mm and a height of 300.5 mm is prepared, an insulating plate is inserted into the bottom of the battery can 47a, and then the spiral laminate 44 is inserted into the battery can 47a as shown in FIG. Store. In this case, the other end of each of the negative electrode lead 45 and the positive electrode lead 46 is welded to the negative electrode terminal 49 and the positive electrode terminal 50 provided on the battery lid 47b.

Then, an electrolytic solution prepared by dissolving LiPF _{6 in an amount} of 1 mol / 1 in a mixed solvent of 50% by volume of propylene carbonate and 50% by volume of diethyl carbonate was injected into the battery can 47a, and thereafter, The battery lid 47b was fixed by caulking the battery lid 47b to the battery can 47a via an insulating sealing gasket coated with asphalt, and a cylindrical large-capacity lithium ion secondary battery with a capacity of 20 Ah was manufactured.

In addition, a safety valve 48 is provided on the battery lid 47b for venting the gas inside when the internal pressure of the sealed battery case 47 becomes higher than a predetermined value.

In the sixth embodiment, as shown in FIG. 9, the positive electrode 40 and the positive electrode 40 are opposed to each other in the radial direction of the spiral laminated body 44 every other pair of the electrode pairs 43.
Since there is an interface 43a of 0 and 41 which do not face each other and a heat insulating heat resistant layer of ZrO ₂ layer is further interposed in the interface 43a, even if an internal short circuit occurs, it is prevented from spreading to the radial electrode pair 43. There is an advantage that the damage to the battery itself and the influence on the surroundings can be minimized.

When a nail penetration test was conducted on the lithium ion secondary battery of Example 6, the weight reduction rate of Example 6 was as low as 21% as shown in Table 1.

As a comparative example 2 (conventional example) to this,
As shown in FIG. 15, the strip-shaped negative electrode 41 of Example 6 described above,
A layer of the positive electrode mixture 4 is provided on both surfaces of the separator 8 and the positive electrode current collector 5, the positive electrode 40 without the heat-resistant heat-resistant layer and the separator 8 are sequentially stacked, and then spirally wound a predetermined number of times along the longitudinal direction. Thus, the spiral laminate 44 was obtained. Others were manufactured in the same manner as in Example 6 to obtain a lithium ion secondary battery having a capacity of 20 Ah, and the nail penetration test was performed for Comparative Example 2.

As shown in Table 1, the result of the nail penetration test of Comparative Example 2 is that the weight loss is large at 125%, and when an internal short circuit occurs, the generated heat spreads between the adjacent electrodes in the radial direction. It indicates that

Next, Examples 7 to 10 will be described. In Example 7, as shown in FIG. 10, instead of the ZrO ₂ layer of Example 6, a heat-insulating heat-resistant layer having a thickness of 13 to 13 having electrolytic solution resistance was used.
A 15 μm Al ₂ O ₃ layer 33 was formed on the surface of the positive electrode current collector 5 of the positive electrode 40 on which the active material was not coated, in the same manner as in Example 2. 20
A large capacity cylindrical lithium ion secondary battery of Ah was manufactured.

In the seventh embodiment, the spiral laminate 44 is used.
In the radial direction of the electrode pair 43, there is an interface 43a between the positive and negative electrodes 40 and 41 that do not face each other and an Al ₂ O ₃ layer 33 exists at this interface 43a, so that an internal short circuit occurs. Also has the advantage that it can be prevented from spilling over to the radial electrode pair 43, and damage to the battery itself and its influence on the surroundings can be minimized.

By the way, when the nail penetration test was conducted on the lithium ion secondary battery of this Example 7, the weight reduction rate of this Example 7 was as small as shown in Table 1 and was 20%.

The eighth embodiment is the same as the Z of the sixth embodiment as shown in FIG.
Instead of the rO ₂ layer, an SiO ₂ layer 34 having a thickness of 13 to 15 μm and having a resistance to electrolytic solution as a heat insulating and heat resistant layer was applied in the same manner as in Example 3 without applying the active material of the positive electrode current collector 5 of the positive electrode 40. A large-capacity cylindrical lithium-ion secondary battery having a capacity of 20 Ah was manufactured by the same method as in Example 6 except for the above-described structure.

Also in the eighth embodiment, the spiral laminate 44 is used.
In the radial direction of, since there is an interface 43a between the positive and negative electrodes 40 and 41 that do not face each other and the SiO ₂ layer 34 exists as a heat-resistant heat-resistant layer every other pair of electrode pairs 43, even if an internal short circuit occurs. The advantage is that it can be prevented from spreading to the radial electrode pair 43, and damage to the battery itself and the influence on the surroundings can be minimized.

When the nail penetration test was conducted on the lithium ion secondary battery of Example 8, the weight reduction rate of Example 8 was 20%, which is small as shown in Table 1.

As Example 9, as shown in FIG. 12, instead of the ZrO ₂ layer of Example 6, as a heat insulating and heat resistant layer, an electrolyte solution-resistant SiO ₂ —B ₂ O ₃ — having a thickness of 13 to 15 μm was used.
A ZnO multi-component glass layer 35 was formed on the surface of the positive electrode current collector 5 of the positive electrode 40 not coated with the active material in the same manner as in Example 4, and the other configurations were the same as in Example 6, and the capacity was 20 A.
A large-capacity cylindrical lithium ion secondary battery of h was manufactured.

In the ninth embodiment, as shown in FIG. 12, one of the electrode pairs 43 is arranged in the radial direction of the spiral laminated body 44.
For each pair, the positive electrode current collectors 5 of the positive electrode 40 are made of SiO.
_2- B ₂ O ₃ —ZnO Interface 43 facing each other through the multi-component glass layer 35 and not facing the positive and negative electrodes 40 and 41.
Since a is present and the multi-component glass layer 35, which is a heat-insulating and heat-resistant layer, is present at this interface 43a, it is possible to prevent spillover to the radial electrode pair 43 even if an internal short circuit occurs. There is a benefit that damage to the battery itself and its impact on the environment can be minimized.

By the way, when a nail penetration test was conducted on the lithium ion secondary battery of this Example 9, this Example 9
As shown in Table 1, the weight loss was as low as 20%.

In Example 10, as shown in FIG. 13, instead of the ZrO ₂ layer 32 of Example 6, an SiO ₂ —PbO—A layer having a thickness of 13 to 15 μm and having an electrolytic solution resistance as a heat insulating and heat resistant layer was used.
The l ₂ O ₃ multi-component glass layer 36 was formed on the surface of the positive electrode current collector 5 of the positive electrode 40 not coated with the active material in the same manner as in Example 5, and the other components were formed in the same manner as in Example 6, Is 20
A large capacity cylindrical lithium ion secondary battery of Ah was manufactured.

In the tenth embodiment, the spiral laminate 4 is used.
In the radial direction of No. 4, there is an interface 43a between the positive and negative electrodes 40 and 41 that does not face each other every other pair of electrodes 43, and SiO ₂ —PbO—Al ₂ is present at this interface 43a.
Due to the presence of the O ₃ multi-component glass layer 36, it is possible to prevent the internal short circuit from spreading to the radial electrode pair 43, and to minimize the damage to the battery itself and the influence on the surroundings. There are benefits that can be.

Incidentally, when a nail penetration test was conducted on the lithium ion secondary battery of this Example 10, the weight reduction rate of this Example 10 was as small as shown in Table 1 and was 20%.

In the above-mentioned embodiment, the interface where the positive electrode and the negative electrode do not face each other was provided every other pair of electrode pairs, and the heat insulating heat resistant layer was interposed at this interface. However, this interface was provided every few pairs. It can be easily understood that even if an adiabatic heat-resistant layer is interposed at the interface, the same effect as that of the above-mentioned embodiment can be obtained.

Further, in the above-mentioned embodiment, the heat insulating and heat-resistant layer is provided on one surface of the positive electrode 2, and the negative electrode 3 is sandwiched between the two positive electrodes 2 to form one pair. On the contrary, one surface of the negative electrode 3 is formed. Needless to say, a heat insulating and heat resistant layer may be provided on the positive electrode 2 so that the positive electrode 2 is sandwiched between the two negative electrodes 3.

Further, as the heat insulating and heat resistant layer provided at this interface, not only the above-mentioned examples but also other films of metal oxide glass having electrolytic solution resistance and spherical fine particle layers can be used. Further, it is apparent that the safety is further improved by making the thickness of the heat insulating and heat resistant layer more than that in the above-mentioned embodiment.

Further, the present invention is not limited to the above-mentioned embodiments, and it goes without saying that various other configurations can be adopted without departing from the gist of the present invention.

[0075]

EFFECTS OF THE INVENTION According to the present invention, a positive electrode and a negative electrode are laminated with a separator interposed therebetween, and an interface where the positive electrode and the negative electrode do not face each other is provided, and a metal oxide having electrolytic solution resistance at the interface. Since the heat insulating and heat-resistant layer of the glass layer is interposed, even if an internal short circuit occurs, it can be prevented from spilling over between the adjacent positive and negative electrodes, and the damage to this battery itself and its influence on the surroundings are minimized. There is a profit that can be suppressed to.

Further, since the metal oxide glass layer according to the present invention may be coated with a coating agent to be vitrified, it can be formed at a relatively low temperature of 200 ° C. or lower, and there is an advantage that the production is easy.

[Brief description of the drawings]

FIG. 1 is an enlarged cross-sectional view showing a main part of an embodiment of a lithium ion secondary battery of the present invention.

FIG. 2 is a perspective view of an example of a flattened type lithium ion secondary battery.

FIG. 3 is a diagram used to explain FIG.

FIG. 4 is a perspective view of an example of a cylindrical lithium ion secondary battery.

FIG. 5 is an enlarged sectional view showing a main part of another embodiment of the present invention.

FIG. 6 is an enlarged cross-sectional view showing the main parts of another embodiment of the present invention.

FIG. 7 is an enlarged sectional view showing a main part of another embodiment of the present invention.

FIG. 8 is an enlarged sectional view showing a main part of another embodiment of the present invention.

FIG. 9 is an enlarged sectional view showing a main part of another embodiment of the present invention.

FIG. 10 is an enlarged sectional view showing a main part of another embodiment of the present invention.

FIG. 11 is an enlarged cross-sectional view showing the main parts of another embodiment of the present invention.

FIG. 12 is an enlarged cross-sectional view showing the main parts of another embodiment of the present invention.

FIG. 13 is an enlarged cross-sectional view showing the main parts of another embodiment of the present invention.

FIG. 14 is an enlarged cross-sectional view showing a main part of an example of a conventional lithium-ion secondary battery.

FIG. 15 is an enlarged cross-sectional view showing a main part of an example of a conventional lithium-ion secondary battery.

[Explanation of symbols]

2,40 Positive electrode 3,41 Negative electrode 4 Positive electrode mixture 5 Positive electrode current collector 6 Negative electrode mixture 7 Negative electrode current collector 8 Separator 10 Flat rectangular battery case 11,50 Positive electrode terminal 12,49 Negative electrode terminal 13,48 Safety valve 14,44 Laminated body 24,43 Electrode pair 25,43a Interface 26,32 ZrO ₂ layer 27,33 Al ₂ O ₃ layer 28,34 SiO ₂ layer 29,35 SiO ₂ —B ₂ O ₃ —ZnO multi-component glass layer _{31,36 SiO 2 -PbO-Al 2 O} 3 multi-component glass layer 45 negative electrode lead 46 positive electrode lead 47 cylindrical battery case

Claims (1)

[Claims] 1. Lithium in which a positive electrode having a positive electrode current collector coated with a positive electrode active material on one or both surfaces and a negative electrode having a negative electrode current collector coated with a negative electrode active material on both sides of a separator are interposed. In an ion secondary battery, a lithium-ion secondary battery characterized in that an interface where the positive electrode and the negative electrode do not face each other is provided, and a heat-insulating heat-resistant layer of a metal oxide glass layer having electrolytic solution resistance is interposed at the interface. battery.