JP4685974B2 - Non-aqueous secondary battery porous membrane, non-aqueous secondary battery separator, non-aqueous secondary battery adsorbent and non-aqueous secondary battery - Google Patents

Description

  The present invention relates to a porous membrane for a non-aqueous secondary battery, a separator for a non-aqueous secondary battery, an adsorbent for a non-aqueous secondary battery, and a non-aqueous secondary battery.

Non-aqueous secondary batteries represented by lithium ion secondary batteries are widely used as main power sources for portable electronic devices such as mobile phones and notebook computers. This non-aqueous secondary battery is required to have higher energy density, higher capacity, and higher output, and this demand is expected to increase in the future. From the viewpoint of meeting such demands, ensuring the safety of the battery becomes a more important technical element.
Generally, a non-aqueous secondary battery has a configuration including a positive electrode, a negative electrode, and a separator disposed between these electrodes. The separator has a function of preventing an internal short circuit between the positive electrode and the negative electrode without hindering the permeation of ions. As the separator, a polyolefin microporous membrane is generally used. The separator made of a microporous polyolefin membrane has a shutdown function such that when the battery temperature rises due to overcharge or the like, the polyolefin melts and closes the pores, thereby blocking the current inside the battery. Have. With this function, further heat generation of the battery can be prevented, and the safety of the battery at high temperatures can be improved. However, if the internal temperature of the battery rises even after the holes are closed, there is a risk that the separator will break and an internal short circuit will occur, leading to ignition and the like.
Therefore, conventionally, heat-resistant porous membranes have attracted attention in order to improve the safety of non-aqueous secondary batteries. According to such a heat-resistant porous film, it is possible to prevent an internal short circuit between the positive and negative electrodes when the battery is exposed to an abnormally high temperature. For example, a technique for applying a porous film made of a heat resistant resin to a separator (Patent Document 1), a technique for applying a porous film made of a heat resistant resin and a ceramic powder to a separator (Patent Documents 2 and 3), an inorganic filler and a binder A technique for forming a porous film made of resin on the electrode surface (Patent Document 4) corresponds to this. A technique for dispersing an inorganic filler in a separator made of a polyolefin microporous film is also known (Patent Document 5). In these techniques, the inorganic filler typified by ceramic powder is considered to be effective from the viewpoint of more reliably preventing internal short circuit between the positive and negative electrodes because of high heat resistance and compressive strength.
However, a battery to which such an inorganic filler is applied may cause a decrease in battery durability such as cycle characteristics and storage characteristics. As one of the causes of the decrease in durability, hydrogen fluoride (HF) present in a minute amount in the battery reacts with the inorganic filler, and the surface of the inorganic filler is fluorinated, and at this time, water is generated. It is conceivable that moisture decomposes the SEI (Solid Electrolyte Interface) film formed on the electrolyte solution or electrode surface. If the electrolytic solution or the SEI film is decomposed in this way, the internal resistance of the battery is increased, or lithium necessary for charging / discharging is deactivated, so that the durability of the battery may be reduced. In addition, when such a decomposition reaction occurs, gas is generated, which may also decrease the durability of the battery. And there is a concern that such a decomposition reaction may cause a decrease in battery safety. In particular, when a heat resistant resin such as an aromatic polyamide resin is used together with an inorganic filler, since the heat resistant resin is generally a substance that easily adsorbs moisture, it can be said that the problem of the decomposition reaction is more likely to occur. .
On the other hand, Patent Document 6 proposes a technique for improving gas generation in a battery with an inorganic filler. In this technique, a gas absorbent made of inorganic powder is mixed in a separator made of polyolefin, and the gas generated in the battery is trapped by the gas absorbent. However, there is a concern that such a separator has insufficient heat resistance. Moreover, since the inorganic filler which is a gas absorbent is mixed in the polyolefin microporous film having the shutdown function, the shutdown function may be remarkably deteriorated. Therefore, although the gas generation is apparently suppressed, the safety of the battery may be reduced as compared with the case where the conventional polyolefin microporous membrane is applied.
As described above, although there is a demand for higher performance in non-aqueous secondary batteries, it is actually difficult to ensure both safety and durability in order to achieve this. In addition, it is considered effective to apply a porous film made of an inorganic filler and a heat-resistant resin in order to enhance safety, but a configuration that can achieve both safety and durability has not yet been found.
By the way, in the technical field of separators and porous membranes, the problem of achieving both battery safety and durability has been described above. However, in the first place, from the viewpoint of preventing the deterioration of the durability of the battery due to HF and water existing in the battery, even if it is considered to be extended to the entire technical area of the non-aqueous secondary battery, there has been sufficient improvement technology in the past. Not proposed. This will be described below.
Generally, a lithium ion secondary battery is composed of a positive electrode such as a lithium transition metal composite oxide, a negative electrode such as a carbon material, an organic electrolytic solution in which a Li salt is dissolved, and a separator such as a polyethylene microporous film. . And such a lithium ion secondary battery is manufactured after strictly managing so that a water | moisture content and an impurity may not mix in a battery system from a viewpoint of cycling characteristics and safety | security. However, it is substantially difficult to completely remove a small amount of moisture adsorbed on the battery constituent member and moisture mixed during battery assembly from the battery system.
Here, moisture present in the battery system reacts with a Li salt such as lithium hexafluorophosphate to liberate HF, and the liberated HF reacts as shown in (1) to (3) below. It is known to deteriorate the cycle characteristics of the battery.
(1) Dissolve the transition metal used in the positive electrode.
(2) When aluminum is used as the positive electrode current collector, the aluminum corrodes.
(3) When graphite is used for the negative electrode, the interface resistance of the negative electrode is increased (see Non-Patent Document 1).
Therefore, conventionally, as one method for improving the cycle characteristics, a technique for adding a porous inorganic filler such as zeolite, silica gel, activated alumina, activated carbon or the like to the battery system has been reported (see, for example, Patent Documents 7 to 9). ).
That is, Patent Document 7 discloses a technique in which an inorganic substance having a specific surface area of 15 to 300 m ² / g is included in a separator, and it is shown that the cycle characteristics are improved by this inorganic substance. Patent Document 8 discloses a technique in which alumina having a specific surface area of 30 to 300 m ² / g is contained in a negative electrode or a positive electrode, and shows that good cycle characteristics can be obtained. Patent Document 9 discloses a configuration in which activated carbon having a specific surface area of 1000 m ² / g or more and an inorganic substance are included in the battery system, and it is shown that good cycle characteristics can be obtained by activated carbon or the like.
Thus, it has been reported that the porous inorganic filler having a specific specific surface area has an effect of improving the cycle characteristics of the battery.
However, when considering the reaction and adsorption with HF as described in (1) to (3) above, it is considered that there is a range of specific surface areas where good cycle characteristics can be obtained in each adsorbent. It is the current situation that has not been clarified. In addition, a technique for suppressing the reaction with HF and improving the cycle characteristics by factors other than the specific surface area of the inorganic filler is not known.

JP 2008-266588 A Japanese Patent No. 3175730 International Publication No. 2008/62727 Pamphlet JP 2008-204788 A Japanese Patent No. 4074116 JP 2008-146963 A Japanese Patent No. 4145762 Japanese Patent No. 3704780 JP 2000-77103 A

Lithium-ion secondary battery 2nd edition (Nikkan Kogyo Shimbun, Masayuki Yoshio) Materials and Applications Pages 76-77

  Therefore, in view of the above-described problems, the first object of the present invention is to provide a technique capable of improving both safety and durability of a non-aqueous secondary battery. A second object is to provide a technique capable of improving cycle characteristics in consideration of reaction with HF and adsorption.

As a result of repeated studies to solve the above problems, the present inventors have found that the problems can be solved by the following configuration, and have reached the present invention.
1. A porous film for a non-aqueous secondary battery comprising a heat resistant resin and an inorganic filler, wherein the inorganic filler has an average particle size of 0.1 to 5.0 μm and a specific surface area of 40 to A porous membrane for a non-aqueous secondary battery, characterized by being a porous filler of 3000 m ² / g.
2. ^{2. The} porous membrane for a non-aqueous secondary battery according to 1 above, wherein the porous filler is activated alumina having a specific surface area of 300 to 1000 m ² / g.
3. A porous film for a non-aqueous secondary battery comprising a heat-resistant resin and an inorganic filler, wherein the inorganic filler is amorphous alumina particles.
4). A nonaqueous secondary battery comprising at least a positive electrode and a negative electrode, wherein the porous film for a nonaqueous secondary battery according to any one of the above 1 to 3 is formed on the surface of at least one of the positive electrode and the negative electrode Alternatively, a non-aqueous secondary battery using the porous membrane for a non-aqueous secondary battery as a separator.
5. A separator for a non-aqueous secondary battery comprising a porous substrate and a heat-resistant porous layer containing a heat-resistant resin and an inorganic filler laminated on one or both surfaces of the porous substrate, A separator for a non-aqueous secondary battery, wherein the inorganic filler is a porous filler having an average particle diameter of 0.1 to 5.0 μm and a specific surface area of 40 to 3000 m ² / g.
6). 6. The separator for a non-aqueous secondary battery according to 5 above, wherein the porous filler is activated alumina having a specific surface area of 300 to 1000 m ² / g.
7). A separator for a non-aqueous secondary battery comprising a porous substrate and a heat-resistant porous layer containing a heat-resistant resin and an inorganic filler laminated on one or both surfaces of the porous substrate, A separator for a non-aqueous secondary battery, wherein the inorganic filler is amorphous alumina particles.
8). A non-aqueous secondary battery comprising a positive electrode, a negative electrode, and a separator, wherein the separator for a non-aqueous secondary battery according to any one of 5 to 7 is used as the separator. battery.
9. An adsorbent for hydrogen fluoride mixed in a non-aqueous secondary battery, the adsorbent being activated alumina particles having a specific surface area of 300 to 1000 m ² / g, for a non-aqueous secondary battery Adsorbent.
10. An adsorbent for hydrogen fluoride mixed in a non-aqueous secondary battery, wherein the adsorbent is amorphous alumina particles.
11. A porous film for a non-aqueous secondary battery comprising an inorganic filler and a binder resin, wherein the inorganic filler includes the non-aqueous secondary battery adsorbent described in 9 or 10 above. A porous membrane for a non-aqueous secondary battery.
12 A separator for a non-aqueous secondary battery comprising a porous base material and a porous layer containing an inorganic filler and a binder resin laminated on one or both sides of the porous base material, the inorganic filler as the inorganic filler A nonaqueous secondary battery separator comprising the adsorbent for a nonaqueous secondary battery as described in 9 or 10 above.
13. A non-aqueous secondary battery comprising a positive electrode, a negative electrode, a non-aqueous electrolyte, and a separator, characterized in that the non-aqueous secondary battery adsorbent described in 9 or 10 is contained in the battery. Non-aqueous secondary battery.

  According to the first aspect of the present invention, it is possible to provide a technique capable of improving both safety and durability of a non-aqueous secondary battery. In addition, according to the second aspect of the present invention, it is possible to provide a technique capable of improving cycle characteristics in consideration of reaction with HF and adsorption.

(1) First invention
(1-1) First form
[Porous membrane for non-aqueous secondary battery]
The porous membrane for a non-aqueous secondary battery according to the first aspect of the present invention is a porous membrane for a non-aqueous secondary battery configured to contain a heat-resistant resin and an inorganic filler, and the inorganic filler has an average particle size The diameter is 0.1 to 5.0 μm and the specific surface area is 40 to 3000 m. ² / G porous filler.
By including a heat-resistant resin and an inorganic filler as in the present invention, it becomes possible to ensure sufficient heat resistance to prevent an internal short circuit even when the battery is exposed to high temperatures, thereby improving the safety of the battery. It can be secured. The inorganic filler has an average particle diameter of 0.1 to 5.0 μm and a specific surface area of 40 to 3000 m. ² Because it is a porous filler of / g, durability such as cycle characteristics and storage characteristics of the battery can be suppressed by suppressing side reactions that reduce durability in the battery and removing gas generated by side reactions. Can be improved.
In particular, since the heat-resistant resin is generally a substance that easily adsorbs moisture, the present invention has a configuration in which the side reaction between the HF and the inorganic filler is likely to occur. By applying the filler, the activity of moisture and HF present in a minute amount in the battery can be significantly reduced, and gas generation due to decomposition of the electrolyte and the like can be suppressed. Even if gas is generated, the porous filler can trap this gas. For this reason, it becomes possible to significantly improve the durability of the battery.
Here, the porous membrane for a battery according to the present invention includes a heat-resistant resin and an inorganic filler, and has a plurality of pores or voids therein, and these pores are connected to each other. Means a quality structure.
The heat-resistant resin in the present invention includes a resin having a melting point of 200 ° C. or higher. In addition to a resin having a melting point of 200 ° C. or higher, a resin having a thermal decomposition temperature of 200 ° C. or higher with substantially no melting point. Is also included. Examples of such a heat-resistant resin include wholly aromatic polyamides, polyimides, polyamideimides, polysulfones, polyketones, polyether ketones, polyether sulfones, polyether imides, celluloses, combinations of two or more thereof, and the like. . Among them, wholly aromatic polyamides are preferable from the viewpoint of durability such as ease of forming a porous structure, binding property with an inorganic filler, strength of the porous film and accompanying oxidation resistance. As for the wholly aromatic polyamide, comparing the para type and the meta type, the meta type wholly aromatic polyamide is preferable from the viewpoint of easy molding, and polymetaphenylene isophthalamide is particularly preferable.
When the meta type wholly aromatic polyamide is applied, when the meta type wholly aromatic polyamide is dissolved in N-methyl-2-pyrrolidone, the logarithmic viscosity of the following formula (1) is 0.8 to 2.5 dl / g. Those within the range are preferable, and those within the range of 1.0 to 2.2 dl / g are more preferable. Deviating from this range is not preferable because the moldability may be deteriorated.
Logarithmic viscosity (unit: dl / g) = ln (T / T0) / C (1)
T: Flow time of capillary viscometer at 30 ° C. of a solution of 0.5 g of meta-type wholly aromatic polyamide resin dissolved in 100 ml of N-methyl-2-pyrrolidone
T0: Flow time of capillary viscometer at 30 ° C. of N-methyl-2-pyrrolidone
C: Concentration of meta-type wholly aromatic polyamide resin in solution (g / dl)
Porous fillers applicable to the present invention include zeolite, activated carbon, activated alumina, porous silica, porous fillers obtained by heat treatment of metal hydroxides such as magnesium hydroxide and aluminum hydroxide, synthesized from organic compounds Porous fillers to be used. Of these, activated alumina is particularly preferable. The activated alumina in the present invention has a formula of Al ₂ O ₃ XH ₂ It is a porous filler represented by O (x can take a value of 0 or more and 3 or less). The surface of activated alumina is amorphous Al ₂ O ₃ , Γ-Al ₂ O ₃ , Χ-Al ₂ O ₃ Gibbsite-like Al (OH) ₃ Boehmite Al ₂ O ₃ ・ H ₂ A structure such as O is preferable, and a porous structure formed of these surface structures is particularly preferable from the viewpoint of reducing the activity of moisture and HF. In addition to the porous filler described above, other non-porous inorganic fillers such as metal oxides such as α-alumina and metal hydroxides such as aluminum hydroxide may be appropriately added as the inorganic filler.
The porous filler is preferably composed of mesopores of 50 nm or less or micropores of 2 nm or less, and particularly preferably has a structure in which micropores of 2 nm or less are developed from the viewpoint of manifestation of the effects of the present invention. .
The average particle size of the porous filler is preferably in the range of 0.1 to 5.0 μm. When the average particle size of the porous filler is smaller than 0.1 μm, it is not preferable because it may be difficult to mold the porous film, or the sliding property of the porous film may be deteriorated and handling may be difficult. When the average particle diameter of the porous filler is larger than 5.0 μm, it may be difficult to form the porous film from the viewpoint of surface roughness when it is thinly formed.
In the present invention, the specific surface area of the porous filler is 40 to 3000 m. ² / G is preferable. Specific surface area is 40m ² If it is less than / g, the activity of moisture and HF cannot be sufficiently reduced, which is not preferable. 3000m ² If it exceeds / g, it becomes difficult to mold the porous membrane, and the strength of the porous membrane may be significantly reduced. In such a case, handling may be hindered, which is not preferable.
When the specific surface area of the porous filler is verified in more detail from the viewpoint of the effect of the present invention, the specific surface area of the porous filler is 40 to 1000 m. ² / G is more preferable. Specific surface area is 1000m ² This is because if it is less than / g, it will be more excellent in terms of mechanical strength and gas generation suppression. More preferably, the specific surface area of the porous filler is 40 to 500 m. ² / G is preferred. Specific surface area of 500m ² This is because if it is less than / g, it will be more excellent in terms of mechanical strength and gas generation suppression. Particularly preferably, the specific surface area of the porous filler is 150 to 500 m. ² / G is preferred. Specific surface area is 150m ² This is because if it is at least / g, it will be more excellent in terms of suppressing gas generation. Here, the specific surface area is obtained by analyzing the adsorption isotherm measured by the nitrogen gas adsorption method using the BET equation.
In particular, in the present invention, the porous filler has a specific surface area of 300 to 1000 m. ² / G activated alumina is preferred. Such activated alumina can reduce the activity of HF by adsorbing or reacting with a small amount of HF generated in the battery, and can further improve the cycle characteristics of the non-aqueous secondary battery. .
The elemental ratio of 0 / Al present on the surface of the activated alumina particles is preferably 1.0 to 2.5 when measured using an X-ray photoelectron spectrometer. More preferably, the element ratio of 0 / Al is 1.2 to 1.8. When the surface is formed with such an element ratio, it is preferable from the viewpoint of reducing the activity of HF or the like.
The true density of the activated alumina is 2.7 to 3.8 g / cm. ³ And more preferably 2.8 to 3.3 g / cm. ³ Range. True density is 2.7 g / cm ³ If it is less than that, it becomes close to aluminum hydroxide and the like, and it is difficult to obtain the effect of reducing the activity of HF. The true density is 3.8 g / cm. ³ If it is larger, the structure of the filler becomes dense, and the gap through which the electrolytic solution enters becomes small, which may reduce the cycle characteristics of the battery.
The specific surface area of the activated alumina is 300 m. ² / G or more is preferable. Specific surface area is 300m ² If it is less than / g, the activity of HF or the like may not be sufficiently reduced. On the other hand, the specific surface area of activated alumina is 1000 m. ² / G or less is preferable, more preferably 500 m ² / G or less is preferred. Specific surface area is 1000m ² It is technically difficult to obtain activated alumina exceeding / g at present.
The porous membrane for a non-aqueous secondary battery of the present invention can be applied to any part as long as it is disposed between both the positive electrode and the negative electrode.
That is, for example, the porous membrane for a non-aqueous secondary battery of the present invention can be applied as a separator disposed between electrodes. In this case, it is preferable that the puncture strength has a sufficient mechanical strength of 200 g or more. Further, those having a Gurley value of 10 to 300 seconds / 100 cc are preferred. In order to obtain such physical properties, the porous membrane for a battery according to the present invention preferably has a porous filler weight of 10 to 50% by weight based on the total weight of the heat resistant resin and the porous filler. . If the weight of the porous filler exceeds 50% by weight, it may be difficult to obtain sufficient mechanical strength. On the other hand, if the weight of the porous filler is less than 10% by weight, the effect of suppressing side reactions in the battery may be reduced, or the permeability may be lowered.
Moreover, when arrange | positioning between the electrodes as a separator for battery porous films of this invention, you may use this porous film for batteries independently. Moreover, in order to add a shutdown function, it may be laminated with a polyolefin microporous film having this function, or a dispersion liquid comprising polyolefin fine particles may be applied to the battery porous film.
Further, the battery porous membrane of the present invention may be directly formed on the electrode. In this case, since the electrode becomes a support having sufficient strength, mechanical strength is not required as compared with the case where the porous membrane for a battery is applied alone as a separator. From such a viewpoint, the weight of the porous filler is preferably 10 to 90% by weight, and more preferably 50 to 90% by weight with respect to the total weight of the heat resistant resin and the porous filler. If the weight of the porous filler is less than 10% by weight, the effect of suppressing side reactions in the battery may be reduced, which is not preferable. Moreover, since it may become difficult to shape | mold when it exceeds 90 weight%, it is not preferable.
As described above, when the battery porous membrane of the present invention is directly formed on the electrode, the battery porous membrane can also serve as a separator. Therefore, a separator for preventing a short circuit between the positive and negative electrodes is not disposed. Also good. In addition to the porous membrane for a battery of the present invention, a battery may be produced by applying only a normal separator such as a polyolefin microporous membrane. In addition, when forming the porous membrane for batteries of this invention directly on an electrode, you may apply to any of a positive electrode and a negative electrode. However, it is preferable to form the positive electrode from the viewpoint of improving the durability of the battery, and it is more preferable to form the positive electrode and the negative electrode.
[Method for producing porous membrane for battery]
Although the manufacturing method of the porous film for non-aqueous secondary batteries of this invention is not specifically limited, For example, it can manufacture with the manufacturing method containing the process of the following (i)-(iv). That is, (i) a step of preparing a coating slurry containing a heat resistant resin, an inorganic filler, and a water-soluble organic solvent, (ii) a step of coating the obtained coating slurry on a support, and (iii) And (iv) a step of solidifying the heat-resistant resin in the coated slurry, and (iv) a step of washing and drying the sheet after the solidification step.
In the step (i), the water-soluble organic solvent is not particularly limited as long as it is a good solvent for the heat-resistant resin. Specific examples of such a water-soluble organic solvent include polar solvents such as N-methylpyrrolidone, dimethylacetamide, dimethylformamide, and dimethylsulfoxide. Further, in the slurry, a solvent that becomes a poor solvent for the heat-resistant resin can be partially mixed and used. By applying such a poor solvent, a microphase separation structure is induced and the formation of a heat-resistant porous layer is facilitated. As the poor solvent, alcohols are preferred, and polyhydric alcohols such as glycol are particularly preferred.
In the step (ii), the amount of slurry applied to the support is 10 to 60 g / m. ² The degree is preferred. Examples of the coating method include a knife coater method, a gravure coater method, a screen printing method, a Mayer bar method, a die coater method, a reverse roll coater method, an ink jet method, a spray method, and a roll coater method. Among them, the reverse roll coater method is preferable from the viewpoint of uniformly applying the coating film.
In the step (iii), as a method for solidifying the heat-resistant resin in the slurry, a method in which a coagulating liquid is sprayed on the support after coating, or in a bath (coagulating bath) containing the coagulating liquid. Examples include a method of immersing the substrate. The coagulation liquid is not particularly limited as long as it can coagulate the heat-resistant resin, but water or a mixed liquid in which an appropriate amount of water is contained in a good solvent used in the slurry is preferable. Here, the mixing amount of water is preferably 40 to 80% by weight with respect to the coagulation liquid.
In the step (iv), the drying method is not particularly limited, but the drying temperature is suitably 50 to 100 ° C. In the case of applying a high drying temperature, it is preferable to apply a method of contacting the roll in order to prevent dimensional change due to heat shrinkage.
Moreover, as a 2nd manufacturing method for obtaining the porous film for non-aqueous secondary batteries of this invention, (v) The coated sheet | seat is dried after the process of said (i) and (ii), for example. It is also possible to carry out the process. In this case, the drying temperature in the step (v) is not particularly limited as long as the water-soluble solvent can be removed, but approximately 50 to 200 ° C. is appropriate. In the case of applying a high drying temperature, it is preferable to apply a method of contacting the roll in order to prevent dimensional change due to heat shrinkage.
In any of the above production methods, a support is used, and as this support, a glass plate, a film made of polyethylene terephthalate (PET), or the like that exhibits sufficient heat resistance against the drying temperature is suitable. Can be used. Moreover, when applying these support bodies, the process of peeling the porous film for batteries of this invention from a support body after the drying of said (iv) (v) is included.
In the present invention, it is also possible to apply a porous material such as a polyolefin microporous film or a nonwoven fabric to the support. In this case, since it can be applied as a porous film for a battery including a support, a peeling step is unnecessary. It is also possible to apply the electrode to the support and directly form the battery porous membrane of the present invention on the electrode. Also in this case, the peeling step is naturally unnecessary.
[Non-aqueous secondary battery]
The non-aqueous secondary battery of the present invention is a non-aqueous secondary battery including at least a positive electrode and a negative electrode, and the porous film for a non-aqueous secondary battery described above is provided on at least one surface of the positive electrode and the negative electrode. The porous film for non-aqueous secondary batteries is used as a separator.
The non-aqueous secondary battery of the present invention is improved in battery safety by applying a battery porous film excellent in heat resistance, and the generation of gas is suppressed by the porous filler in the battery porous film. It also has excellent durability such as characteristics and storage characteristics.
As described above, the battery porous membrane of the present invention may be applied as a separator or may be formed on the electrode surface. When applied as a separator, only the porous film for a battery may be applied alone, or the porous film for a battery may be laminated with a polyolefin microporous film. When the porous membrane for a battery is formed on the electrode surface, it may be formed on either the positive electrode or the negative electrode, or both. When the battery porous membrane is formed on the electrode surface, a polyolefin microporous membrane or the like may be applied as a separator, or the battery porous membrane of the present invention is formed in advance on the electrode surface, so that no separator is used. The positive electrode and the negative electrode may be joined together.
However, when a polyolefin microporous membrane is applied to the separator, a configuration in which the battery porous membrane of the present invention is at least between the polyolefin microporous membrane and the positive electrode is preferable. The oxidation resistance of polyolefin microporous membranes is not necessarily sufficient for application to non-aqueous secondary batteries. Polyolefin microporous membranes may oxidize the surface in contact with the positive electrode, which may deteriorate the battery. By disposing the porous membrane for a battery of the invention as described above, this deterioration can be greatly suppressed.
The type and configuration of the non-aqueous secondary battery of the present invention is not limited to the above configuration, but the battery element in which the positive electrode, the separator, and the negative electrode are sequentially laminated is impregnated with the electrolyte, and this is enclosed in the exterior Any structure can be applied as long as the structure is the same. However, as described above, the separator can be omitted.
The negative electrode has a structure in which a negative electrode mixture composed of a negative electrode active material, a conductive additive and a binder is formed on a current collector. As the current collector, for example, copper foil, stainless steel foil, nickel foil or the like is used. As the negative electrode active material, a material capable of electrochemically doping lithium, for example, a carbon material, silicon, aluminum, tin, or the like is used.
The positive electrode has a structure in which a positive electrode mixture composed of a positive electrode active material, a conductive additive and a binder is formed on a current collector. As the current collector, for example, copper foil, stainless steel foil, nickel foil or the like is used. Examples of the positive electrode active material include lithium-containing transition metal oxides such as LiCoO. ₂ , LiNiO ₂ , LiMn _0.5 Ni _0.5 O ₂ LiCo _1/3 Ni _1/3 Mn _1/3 O ₂ , LiMn ₂ O ₄ LiFePO ₄ Is used.
The electrolytic solution has a structure in which a lithium salt is dissolved in a non-aqueous solvent. Examples of the lithium salt include LiPF. ₆ , LiBF ₄ LiClO ₄ Etc. Examples of the non-aqueous solvent include propylene carbonate, ethylene carbonate, dimethyl carbonate, diethyl carbonate, ethyl methyl carbonate, γ-butyrolactone, vinylene carbonate, and the like.
Examples of the exterior material include a metal can or an aluminum laminate pack. The shape of the battery includes a square shape, a cylindrical shape, a coin shape, and the like, but the separator of the present invention can be suitably applied to any shape. However, when the battery porous membrane of the present invention is formed on an electrode, it is more preferable to apply to a cylindrical battery.
(1-2) Second form
The porous membrane for a non-aqueous secondary battery according to the second aspect of the present invention is a porous membrane for a non-aqueous secondary battery configured to contain a heat-resistant resin and an inorganic filler, and the inorganic filler is amorphous. Alumina particles (hereinafter referred to as amorphous alumina as appropriate).
According to the present invention as described above, the same effects as those of the first embodiment described above can be obtained. In particular, since amorphous alumina adsorbs a small amount of impurities and by-products such as HF present in the battery, the cycle characteristics of the battery can be further improved.
In addition, since this 2nd form is the same as the 1st form mentioned above except the point which changed the inorganic filler into the amorphous alumina, below, description is abbreviate | omitted suitably about the structure similar to a 1st form. To do. In addition, the “amorphous alumina” in the second form is the “specific surface area of 300 to 1000 m in the first form described above. ² "/ G activated alumina" has an effect that is very similar, and the one that captures the invention from the viewpoint of specific surface area corresponds to the first form, and the one that captures from the viewpoint of crystal structure is the second form. It corresponds to.
In the present invention, amorphous alumina particles are those having a formula of Al. ₂ O ₃ XH ₂ It is a filler represented by O (x can take a value of 0 or more and 3 or less), and a clear crystal peak is not confirmed by analysis by X-ray diffraction. In addition, amorphous alumina does not have a clear crystal peak completely confirmed by X-ray diffraction analysis, but has a slightly clear crystal peak in a broad peak (amorphous and other compositions). And mixed composition).
The “other composition” includes gibbsite-like or bayerite-like Al (OH). ₃ Boehmite or diaspore Al ₂ O ₃ ・ H ₂ O, γ-Al ₂ O ₃ Or χ-Al ₂ O ₃ Α-Al, which is an intermediate alumina such as ₂ O ₃ Among these, boehmite or gibbsite is preferable in that the effects of the present invention can be satisfactorily obtained.
The “slightly clear crystal peak” is, for example, observed in the vicinity of 2θ = 14 ° when measured under the conditions described in the examples described later when the boehmite structure is included in amorphous alumina. If the integrated intensity of the main peak is 10 cps · deg or more, and this integrated intensity is 0.30 or less with respect to the integrated intensity of the broad peak existing over 2θ = 10 to 60 deg, the entire inorganic filler Can be said to be amorphous. For example, in the case of a gibbsite structure, 2θ = 18 °, in the case of a bayerite structure, 2θ = 19 °, in the case of a diaspore structure, 2θ = 20 °, γ-Al ₂ O ₃ In the case of the structure, 2θ = 46 °, χ-Al ₂ O ₃ In the case of structure, 2θ = 67 °, α-Al ₂ O ₃ In the case of the structure, even when the integrated intensity of the main peak observed in the vicinity of 2θ = 43 ° is 0.30 or less with respect to the integrated intensity of the broad peak existing over 2θ = 10-60 deg, the inorganic filler as a whole It can be said to be amorphous.
The 0 / Al element ratio present on the surface of the amorphous alumina is preferably 1.0 to 2.5 when measured using an X-ray photoelectron spectrometer. More preferably, the element ratio of 0 / Al is 1.2 to 1.8. When the surface is formed with such an element ratio, it is preferable from the viewpoint of reducing the activity of hydrogen fluoride (HF) or the like in the battery.
The amorphous alumina preferably has a porous structure with a large adsorption area for adsorbing various impurities and by-products mixed in the battery system. The porous structure referred to here means a structure in which a large number of micropores or microvoids are formed inside or on the surface of the particle.
The amorphous alumina is preferably configured to include mesopores of 50 nm or less or micropores of 2 nm or less, and in particular, from the viewpoint of manifesting the effects of the present invention, the structure has developed micropores of 2 nm or less. preferable.
The specific surface area of the amorphous alumina is 50 m. ² / G or more is preferable. Specific surface area is 50m ² If it is less than / g, deterioration of cycle characteristics due to moisture, impurities, etc. cannot be sufficiently suppressed. On the other hand, the specific surface area of amorphous alumina is 1000m. ² / G or less is preferable, more preferably 500 m ² / G or less is preferred. Specific surface area is 1000m ² It is technically difficult to obtain activated alumina exceeding / g at present.
The average particle diameter of the amorphous alumina is preferably in the range of 0.1 to 5.0 μm. If the average particle diameter of the amorphous alumina is smaller than 0.1 μm, it is not preferable because it may be difficult to mold the porous film, or the sliding property of the porous film may be deteriorated and handling may be difficult. Moreover, when the average particle diameter of amorphous alumina is larger than 5.0 μm, it may be difficult to form the porous film from the viewpoint of surface roughness when it is thinly formed, which is not preferable.
Note that amorphous alumina may be used by mixing other inorganic fillers such as metal oxides such as α-alumina, metal hydroxides such as aluminum hydroxide, and the like.
(1-3) Third form
[Separator for non-aqueous secondary battery]
The separator for a non-aqueous secondary battery according to the third aspect of the present invention is a heat-resistant porous material including a porous substrate and a heat-resistant resin and an inorganic filler laminated on one or both surfaces of the porous substrate. A separator for a non-aqueous secondary battery, wherein the inorganic filler has an average particle size of 0.1 to 5.0 μm and a specific surface area of 40 to 3000 m. ² / G porous filler.
By including a heat-resistant resin and an inorganic filler as in the present invention, it becomes possible to ensure sufficient heat resistance to prevent an internal short circuit even when the battery is exposed to high temperatures, thereby improving the safety of the battery. Can be secured. Moreover, since it is the structure which forms a heat resistant porous layer in a porous base material, it becomes easy to ensure sufficient mechanical strength as a separator. The inorganic filler has an average particle diameter of 0.1 to 5.0 μm and a specific surface area of 40 to 3000 m. ² Because it is a porous filler of / g, durability such as cycle characteristics and storage characteristics of the battery can be suppressed by suppressing side reactions that reduce durability in the battery and removing gas generated by side reactions. Can be improved.
In addition, since this 3rd form is the structure which formed the porous film for batteries in the 1st form mentioned above as a heat resistant porous layer on the porous base material, in the following, the 1st form The description of the same configuration as that of the embodiment is omitted as appropriate.
In the present invention, the porous substrate is not particularly limited as long as it has a large number of pores or voids inside and has a porous structure in which these pores are connected to each other. Examples thereof include microporous membranes, nonwoven fabrics, paper-like sheets, and other sheets having a three-dimensional network structure. Among these, a microporous membrane is preferable from the viewpoint of handling properties and strength. As the material constituting the porous substrate, both organic materials and inorganic materials can be used, but thermoplastic resins such as polyolefins are preferable from the viewpoint of obtaining shutdown characteristics. Therefore, if such a polyolefin porous substrate is applied, both heat resistance and a shutdown function can be achieved.
Examples of the polyolefin resin include polyethylene, polypropylene, polymethylpentene, and the like. Among them, those containing 90% by weight or more of polyethylene are preferable from the viewpoint of obtaining good shutdown characteristics. As the polyethylene, for example, low density polyethylene, high density polyethylene, ultrahigh molecular weight polyethylene and the like are preferably used, and particularly, high density polyethylene and ultra high molecular weight polyethylene are suitable. Furthermore, polyethylene comprising a mixture of high density polyethylene and ultra high molecular weight polyethylene is preferred from the viewpoint of strength and moldability. The molecular weight of polyethylene is preferably 100,000 to 10,000,000 in terms of weight average molecular weight, and particularly preferably a polyethylene composition containing at least 1% by weight of ultrahigh molecular weight polyethylene having a weight average molecular weight of 1,000,000 or more. In addition, the porous substrate in the present invention may be constituted by mixing other polyolefins such as polypropylene and polymethylpentene in addition to polyethylene, or two or more layers of a polyethylene microporous membrane and a polypropylene microporous membrane. You may comprise as a laminated body of.
In the present invention, the film thickness of the porous substrate is not necessarily limited, but a range of about 5 to 20 μm is preferable. If the film thickness is less than 5 μm, sufficient strength cannot be obtained, handling becomes difficult, and the yield of the battery may be significantly reduced. When the film thickness is larger than 20 μm, it is not preferable because the movement of ions becomes difficult or the volume occupied by the separator in the battery increases and the energy density of the battery may be lowered.
The porosity of the porous substrate is preferably 10 to 60%, more preferably 20 to 50%. When the porosity is lower than 10%, it is difficult to maintain an amount of electrolyte sufficient for battery operation, and the charge / discharge characteristics of the battery may be significantly deteriorated. If the porosity exceeds 60%, the shutdown characteristics may be insufficient or the strength may be lowered, which is not preferable.
The puncture strength of the porous substrate is preferably 200 g or more, more preferably 250 g or more, more preferably 300 g or more. If the piercing strength is lower than 200 g, the strength for preventing a short circuit between the positive and negative electrodes of the battery is not sufficient, and there may be a problem that the manufacturing yield does not increase.
The Gurley value (JIS P8117) of the porous substrate is preferably in the range of 100 to 500 seconds / 100 cc, more preferably in the range of 100 to 300 seconds / 100 cc. When the Gurley value is lower than 100 seconds / 100 cc, although ion permeability is excellent, shutdown characteristics and mechanical strength may be deteriorated, which is not preferable. On the other hand, if the Gurley value is larger than 500 seconds / 100 cc, the ion permeability becomes insufficient and the load inertia of the battery may be deteriorated, which is not preferable.
The average pore size of the porous substrate is preferably 10 to 100 nm. If the average pore diameter is smaller than 10 nm, it may be difficult to impregnate the electrolytic solution, which is not preferable. When the average pore diameter is larger than 100 nm, the interface may be clogged when the heat-resistant porous layer is formed, or the shutdown characteristics may be significantly deteriorated when the porous layer is formed. .
The heat-resistant porous layer in the present invention includes a heat-resistant resin and an inorganic filler, and has a porous structure in which a large number of pores or voids are formed inside and these pores are connected to each other. It has become. Such a heat-resistant porous layer is preferably an embodiment in which the inorganic filler is directly fixed on the porous substrate in a state where the inorganic filler is dispersed and bound in the heat-resistant resin, from the viewpoint of handling properties and the like. It should be noted that a porous layer made of only a heat resistant resin is formed on a porous substrate, and a solution containing an inorganic filler is subsequently applied and immersed in the hole or surface of the heat resistant resin layer. The aspect which the inorganic filler adhered may be sufficient. Further, the heat-resistant porous layer may be configured as an independent porous sheet such as a microporous film, a nonwoven fabric, or a paper-like sheet, and the porous sheet may be adhered to the porous substrate. Good.
The separator for a non-aqueous secondary battery of the present invention is characterized in that the above-mentioned inorganic filler is contained in the heat-resistant porous layer, but the inorganic filler is not contained in the porous substrate. Is one of the features. The function of the inorganic filler can be expected to be expressed even if it is not present in the porous layer. For example, even if the inorganic filler is contained in the porous substrate, the effect of suppressing gas generation can be obtained. . However, such a configuration is not preferable because, when a polyolefin porous substrate is applied, the shutdown function may be significantly impaired. For this reason, it is preferable in terms of construction that an inorganic filler is not contained in a layer that is expected to have a shutdown function but is contained in a porous layer that is expected to have heat resistance.
The composition of the porous layer is preferably in the range of heat-resistant resin: inorganic filler = 10: 90 to 80:20, and more preferably in the range of 10:90 to 50:50, by weight ratio. When the content of the inorganic filler is less than 20% by weight, it may be difficult to sufficiently obtain the characteristics of the inorganic filler, which is not preferable. If the content of the inorganic filler exceeds 90% by weight, it may be difficult to mold, which is not preferable. On the other hand, those containing 50% by weight or more of the inorganic filler are preferable because heat resistance characteristics such as an effect of suppressing thermal shrinkage are improved.
The porosity of the heat resistant porous layer is preferably in the range of 30 to 80%. Furthermore, the porosity of the heat resistant porous layer is preferably higher than the porosity of the porous substrate. Such a configuration has advantages in characteristics such as better ion permeability and good shutdown characteristics.
When the heat resistant porous layer is formed on both surfaces of the porous substrate, the total thickness of the heat resistant porous layer is preferably 2 μm or more and 12 μm or less. When the porous porous layer is formed only on one side, it is preferably 2 μm or more and 12 μm or less.
The nonaqueous secondary battery separator of the present invention preferably has a thickness of 7 to 25 μm, more preferably 10 to 20 μm. If the film thickness is thinner than 7 μm, it is not preferable from the viewpoint of mechanical strength. Further, if it exceeds 25 μm, it is not preferable from the viewpoint of ion permeability, and it is also not preferable from the viewpoint that the volume occupied by the separator in the battery is increased and the energy density is lowered.
The porosity of the separator for nonaqueous secondary batteries of the present invention is preferably 20 to 70%, more preferably 30 to 60%. If the porosity is lower than 20%, it may be difficult to hold a sufficient amount of electrolyte for battery operation, which is not preferable. If the porosity exceeds 70%, the shutdown characteristics may be insufficient, and the strength and heat resistance may be lowered.
The puncture strength of the separator for a non-aqueous secondary battery of the present invention is preferably 200 g or more, more preferably 250 g or more, and further preferably 300 g or more. If the piercing strength is lower than 200 g, the strength for preventing a short circuit between the positive and negative electrodes of the battery is not sufficient, which may cause a problem that the production yield does not increase, which is not preferable.
The Gurley value (JIS P8117) in the nonaqueous secondary battery separator of the present invention is preferably in the range of 150 to 600 seconds / 100 cc, more preferably in the range of 150 to 400 seconds / 100 cc. When the Gurley value is lower than 150 seconds / 100 cc, although ion permeability is excellent, shutdown characteristics and mechanical strength may be deteriorated, which is not preferable. Further, when forming the porous layer, there is a possibility that a problem such as clogging may occur at the interface between the porous substrate and the heat-resistant porous layer. When the Gurley value is larger than 600 seconds / 100 cc, the ion permeability becomes insufficient and the load characteristics of the battery may be deteriorated.
The value obtained by subtracting the Gurley value of the porous substrate applied to the Gurley value of the separator for a non-aqueous secondary battery of the present invention is preferably 250 seconds / 100 cc or less, and more preferably 200 seconds / 100 cc or less. . A smaller value is preferable in terms of characteristics such as better shutdown characteristics and improved ion permeability.
In the present invention, the heat-resistant porous layer may be formed on at least one surface of the porous substrate, but it is more preferable to form it on both the front and back surfaces of the porous substrate. By forming a heat-resistant porous layer on both the front and back sides of the porous substrate, handling properties are improved without curling, heat resistance such as dimensional stability at high temperatures is improved, and cycle characteristics of the battery are also significantly improved. The effect is obtained.
[Method for producing separator for non-aqueous secondary battery]
Although the manufacturing method of the separator for non-aqueous secondary batteries of this invention is not specifically limited, For example, it can manufacture with the manufacturing method including the process of the following (i)-(iv). That is, (i) a step of producing a coating slurry containing a heat-resistant resin, an inorganic filler, and a water-soluble organic solvent, and (ii) coating the obtained coating slurry on one or both surfaces of a porous substrate. And (iii) a step of coagulating the heat resistant resin in the coated slurry, and (iv) a step of washing and drying the sheet after the coagulation step. . In addition, these processes (i)-(iv) are the same as that of the case of the 1st form mentioned above.
In the present invention, the method for producing the porous substrate is not particularly limited. For example, a polyolefin microporous film as a porous substrate can be produced as follows. That is, a gel-like mixture of polyolefin and liquid paraffin is extruded from a die and then cooled to produce a base tape, which is stretched and heat-set. Thereafter, liquid paraffin is extracted by immersing it in an extraction solvent such as methylene chloride, and then the extraction solvent is dried to obtain a polyolefin microporous membrane.
[Non-aqueous secondary battery]
The nonaqueous secondary battery according to the third aspect of the present invention is a nonaqueous secondary battery including a positive electrode, a negative electrode, and a separator, and the separator for a nonaqueous secondary battery described above is used as the separator. It is characterized by. Such a non-aqueous secondary battery is excellent in safety and durability at high temperatures, and is excellent in cycle characteristics and the like. Other battery configurations are the same as those in the first embodiment described above.
(1-4) Fourth form
The separator for a non-aqueous secondary battery according to the fourth aspect of the present invention is a heat-resistant porous material including a porous substrate and a heat-resistant resin and an inorganic filler laminated on one or both sides of the porous substrate. A separator for a non-aqueous secondary battery, wherein the inorganic filler is amorphous alumina particles.
According to the present invention as described above, the same effects as those of the third embodiment described above can be obtained. In particular, since amorphous alumina adsorbs a small amount of impurities and by-products such as HF present in the battery, the cycle characteristics of the battery can be further improved.
In addition, since this 4th form is the same as the 3rd form mentioned above except the point which changed the inorganic filler into the amorphous alumina, description is abbreviate | omitted about the structure similar to a 3rd form.
(2) Second invention
The first aspect of the present invention described above is a configuration that solves the problem of compatibility between battery safety and durability in the technical field of separators and the like. ² The structure using “/ g activated alumina” or “amorphous alumina” significantly lowers the activity of HF and is therefore excellent in the effect of improving the cycle characteristics of the battery. Therefore, in the second aspect of the present invention, focusing on this effect, “active alumina” and “amorphous alumina” are regarded as adsorbents of hydrogen fluoride, and this adsorbent is applied to each part of a non-aqueous secondary battery. explain.
(2-1) Fifth form
The non-aqueous secondary battery adsorbent according to the fifth aspect of the present invention is an adsorbent of hydrogen fluoride mixed in the non-aqueous secondary battery, and the adsorbent has a specific surface area of 300 to 1000 m. ² / G of activated alumina particles.
In the present invention, the specific surface area is 300 to 1000 m as the adsorbent for the non-aqueous secondary battery. ² / G activated alumina, this activated alumina adsorbs or reacts with a small amount of HF generated in the battery, thereby reducing the HF activity and improving the cycle characteristics of the non-aqueous secondary battery. Can be made. Conventionally, there has been a technique that specifies only the specific surface area without specifying the type of porous filler, but the present invention is from the aspect that activated alumina having a specific surface area decreases the activity of HF. The present invention has been made by finding that it exhibits excellent cycle characteristics different from other porous inorganic fillers. The details of why activated alumina is superior are not known. However, as one of the reasons, since alumina is an amphoteric oxide known as a Lewis acid / Lewis base, it can be considered that HF was polarized and HF was trapped efficiently. Also, the specific surface area is 300m ² It is considered that the surface reaction was smoothly performed and the cycle characteristics were improved by setting the amount to / g or more. Specific surface area is 1000m ² It is technically difficult to obtain activated alumina exceeding / g at present.
In the fifth embodiment, the specific surface area is 300 to 1000 m. ² The configuration of the “/ g activated alumina particles” is the same as that in the first embodiment described above, and thus the description thereof is omitted.
[Location of activated alumina]
The following (A)-(C) are mentioned as an aspect containing the said activated alumina.
(A) A porous membrane for a non-aqueous secondary battery comprising an inorganic filler and a binder resin, wherein the activated alumina is contained as the inorganic filler. film.
(B) A separator for a non-aqueous secondary battery comprising a porous substrate and a porous layer containing an inorganic filler and a binder resin laminated on one or both surfaces of the porous substrate, A separator for a non-aqueous secondary battery, wherein the activated alumina is contained as an inorganic filler.
(C) A nonaqueous secondary battery comprising a positive electrode, a negative electrode, a nonaqueous electrolyte, and a separator, wherein the activated alumina is contained in the battery.
As shown in the above (A) to (C), the activated alumina may be contained in a separator, may be contained in a porous film laminated on a separator or an electrode, or contained in a positive electrode and a negative electrode. In addition, you may make it contain in electrolyte solution. However, when mixed with the electrode mixture, the volume of the active material is reduced correspondingly, and the battery capacity is impaired. Therefore, an embodiment in which activated alumina is contained in the separator is preferable. Furthermore, in order to achieve both the shutdown function and the heat resistance function, the surface of the porous substrate made of a thermoplastic resin such as polyethylene is coated with a heat resistant porous layer made of a heat resistant resin such as polyamide, An embodiment in which activated alumina is contained in the heat resistant porous layer is preferred.
When the active alumina is included in the positive electrode, the positive electrode active material, the binder, and the conductive agent in the first embodiment described above and the active alumina are uniformly mixed to produce a positive electrode mixture. Disperse in a solvent to make a positive electrode mixture slurry. Next, the positive electrode mixture is applied to the positive electrode current collector by, for example, a doctor blade method. Subsequently, the positive electrode containing activated alumina is obtained by drying at high temperature to volatilize the solvent and pressurizing. In addition, the active alumina is fixed on the positive electrode by coating the active material side of the positive electrode with a coating solution in which the active alumina is dispersed in a solvent such as NMP without containing the active alumina in the positive electrode mixture and drying. Is also effective.
When the negative electrode contains the activated alumina, the negative electrode active material, the binder, and the conductive agent in the first embodiment described above and the active alumina are uniformly mixed to prepare a negative electrode mixture. Disperse in a solvent to make a negative electrode mixture slurry. Then, after applying this negative electrode mixture to the negative electrode current collector in the same manner as the positive electrode, the negative electrode containing activated alumina is obtained by drying at high temperature to volatilize and pressurize the solvent. In addition, the active alumina is fixed on the negative electrode by coating the active material side of the negative electrode with a coating solution in which the active alumina is dispersed in a solvent such as NMP without containing the active alumina in the negative electrode mixture. Is also effective.
When the separator contains the activated alumina, for example, after adding the activated alumina to a thermoplastic resin such as polyethylene, the step of melt-kneading to prepare a thermoplastic resin solution containing the activated alumina, this solution from the die Extruding and cooling to form a gel-like molded product, a primary stretching step and a secondary stretching step, a step of removing the liquid solvent from the gel-shaped molded product, and a step of drying the obtained film, A separator can be obtained as a thermoplastic resin microporous film containing activated alumina. In addition, for example, a coating solution in which a binder resin such as aromatic polyamide and activated alumina are uniformly dispersed is applied on a base film such as a polypropylene film, solidified, washed and dried, and then the coating film is peeled off. Can also be obtained.
In the case of a laminated separator, activated alumina may be contained in any one of the layers, or in all layers. For example, when a coating liquid in which a heat-resistant resin such as aromatic polyamide and activated alumina are uniformly dispersed is coated on one or both surfaces of a porous substrate such as a polyethylene microporous film or nonwoven fabric, a laminated separator containing activated alumina Is obtained. In addition, for example, a porous substrate such as a nonwoven fabric is immersed in a coating solution in which a binder resin such as PVdF and activated alumina is uniformly dispersed, taken out, and then washed and dried to obtain a composite separator. It can also be obtained.
In addition, as the binder resin for binding the activated alumina in the separator and the porous film described above, in addition to a heat-resistant resin such as aromatic polyamide, thermoplastics such as polyvinylidene fluoride (PVdF), PVdF copolymer, polyethylene, etc. Examples thereof include resins. Since the configurations of the heat-resistant resin, the porous substrate, the electrode in the non-aqueous secondary battery, the electrolytic solution, the exterior material, and the like are described in detail in the first embodiment described above, the description thereof is omitted.
(2-2) Sixth form
The non-aqueous secondary battery adsorbent according to the sixth aspect of the present invention is an adsorbent of hydrogen fluoride mixed in the non-aqueous secondary battery, and the adsorbent is amorphous alumina particles. It is characterized by that.
In the present invention, since amorphous alumina is used as the adsorbent for non-aqueous secondary batteries, amorphous alumina adsorbs minute impurities generated in the battery and by-products such as HF. Cycle characteristics can be improved.
In addition, since this 6th form is the same as that of the 5th form mentioned above except the point which changed the adsorbent into amorphous alumina, description is abbreviate | omitted about the structure similar to the 5th form mentioned above. In addition, as described above, “specific surface area is 300 to 1000 m. ² / G activated alumina "and" amorphous alumina "are very similar to each other. The activated alumina is the one that captures the invention from the viewpoint of the specific surface area, and the amorphous alumina is the one that captures the crystal structure. It is. As an aspect containing the said amorphous alumina, it is the same as that of the aspect of (A)-(C) in the 5th form mentioned above. Furthermore, the amorphous alumina is preferably contained in any part between the positive electrode and the negative electrode in order to suppress internal short circuit.

［非水系二次電池の作製］
上記のようにして作製した実施例１−１〜１−５および比較例１−１〜１−５の各多孔膜を用いて、以下のようにして非水系二次電池を作製した。
コバルト酸リチウム（ＬｉＣｏＯ_２；日本化学工業社製）粉末８９．５重量部、アセチレンブラック（電気化学工業社製；商品名デンカブラック）４．５重量部、ポリフッ化ビニリデン（クレハ化学社製）６重量部となるようにＮ−メチル−２ピロリドン溶媒を用いてこれらを混練し、スラリーを作製した。得られたスラリーを厚さが２０μｍのアルミ箔上に塗布乾燥後プレスし、１００μｍの正極を得た。
メソフェーズカーボンマイクロビーズ（ＭＣＭＢ：大阪瓦斯化学社製）粉末８７重量部、アセチレンブラック（電気化学工業社製；商品名デンカブラック）３重量部、ポリフッ化ビニリデン（クレハ化学社製）１０重量部となるようにＮ−メチル−２ピロリドン溶媒を用いてこれらを混練し、スラリーを作製した。得られたスラリーを厚さが１８μｍの銅箔上に塗布乾燥後プレスし、９０μｍの負極を得た。
上記正極及び負極を、セパレータを介して対向させた。これに電解液を含浸させアルミラミネートフィルムからなる外装に封入して非水系二次電池を作製した。ここで、電解液には１Ｍ ＬｉＰＦ_６エチレンカーボネート／エチルメチルカーボネート（３／７重量比）（キシダ化学社製）を用いた。
ここで、セパレータとしては実施例１−１〜１−５および比較例１−１〜１−５の各多孔膜を用い、それぞれ表２に示す実施例１−６〜１−１０および比較例１−６〜１−１０の非水系二次電池を作製した。なお、実施例１−３，１−４の多孔膜は、ポリエチレン微多孔膜（ＰＥ微多孔膜）と積層させて用いた。ここで用いたＰＥ微多孔膜は次のような方法で作製した。
まず、ポリエチレンパウダーとしてＴｉｃｏｎａ社製のＧＵＲ２１２６（重量平均分子量４１５万、融点１４１℃）とＧＵＲＸ１４３（重量平均分子量５６万、融点１３５℃）を用いた。ＧＵＲ２１２６とＧＵＲＸ１４３とを１：９（重量比）となるようにして、ポリエチレン濃度が３０重量％となるように流動パラフィン（松村石油研究所社製；スモイルＰ−３５０Ｐ；沸点４８０℃）とデカリンの混合溶媒中に溶解させ、ポリエチレン溶液を作製した。該ポリエチレン溶液の組成はポリエチレン：流動パラフィン：デカリン＝３０：４５：２５（重量比）である。
このポリエチレン溶液を１４８℃でダイから押出し、水浴中で冷却してゲル状テープ（ベーステープ）を作製した。該ベーステープを６０℃で８分、９５℃で１５分乾燥し、該ベーステープを縦延伸、横延伸と逐次行い二軸延伸した。ここで縦延伸は延伸倍率５．５倍、延伸温度９０℃、横延伸は延伸倍率１１．０倍、延伸温度は１０５℃とした。延伸の後に１２５℃で熱固定を行った。次にこれを塩化メチレン浴に浸漬し、流動パラフィンとデカリンを抽出した。その後、５０℃で乾燥し、１２０℃でアニール処理することで、膜厚９μｍのポリエチレン微多孔膜を得た。
［オーブンテスト］
上述のようにして作製した各電池を０．２Ｃ、４．２Ｖの定電圧・定電流充電で８時間充電した。それに１．８ｋｇ／ｃｍ^２の荷重を印加した状態でオーブンに入れ、３０℃から昇温速度５℃／ｍｉｎで１５０℃まで昇温した後、１５０℃にて１時間保持した。このとき、発煙したものを×と評価し、そうでなかったものを○と評価した。結果を表２に示す。
［サイクル特性］
上述のようにして作製した各電池のサイクル特性を評価した。サイクル特性の評価は１Ｃ ４．２Ｖ ２時間の定電流・定電圧充電、１Ｃ、２．７５Ｖカットオフの定電流放電にて充放電を行い、１サイクル目の容量を基準としたときの３００サイクル目の容量維持率をサイクル特性の指標とした。なお、測定時の温度は３０℃とした。結果を表２に示す。
［保存テスト］
上述のようにして作製した電池を０．２Ｃ、４．２Ｖの定電圧・定電流充電で８時間充電した。それに１．８ｋｇ／ｃｍ^２の荷重を印加した状態でオーブンに入れ、８５℃で３日間保存した。保存後、０．２Ｃ、２．７５Ｖカットオフの定電流放電を行い、残存容量を求めた。残存容量を初期容量で割った値に１００をかけて容量維持率を計算した。この容量維持率を保存テストの評価の指標とした。結果を表２に示す。
［電池の膨れ］
上記の保存テスト後の各電池を目視で確認して、電池が明らかに膨らんでいたものについては×と判断し、電池の膨みが外観上分からなかったものについては○と判断した。なお、この場合の電池のふくれは、電池内でガスが発生したことによるものである。結果を表２に示す。

［実施例１−１１］
コバルト酸リチウム（ＬｉＣｏＯ_２；日本化学工業社製）粉末８９．５重量部、アセチレンブラック（電気化学工業社製；商品名デンカブラック）４．５重量部、ポリフッ化ビニリデン（クレハ化学社製）６重量部となるようにＮ−メチル−２ピロリドン溶媒を用いてこれらを混練し、スラリーを作製した。得られたスラリーを厚さが２０μｍのアルミ箔上に塗布乾燥後プレスし、１００μｍの正極を得た。
実施例１−４で作製したスラリーを上記の正極表面に塗工し、これを重量比で水：ＤＭＡｃ：ＴＰＧ＝７０：１８：１２（重量比）で３０℃となっている凝固液中に浸漬し、次いで水洗、乾燥を行い、正極表面に厚み３μｍの本発明の電池用多孔膜を形成した。
メソフェーズカーボンマイクロビーズ（ＭＣＭＢ：大阪瓦斯化学社製）粉末８７重量部、アセチレンブラック（電気化学工業社製；商品名デンカブラック）３重量部、ポリフッ化ビニリデン（クレハ化学社製）１０重量部となるようにＮ−メチル−２ピロリドン溶媒を用いてこれらを混練し、スラリーを作製した。得られたスラリーを厚さが１８μｍの銅箔上に塗布乾燥後プレスし、９０μｍの負極を得た。
上記正極及び負極を、セパレータを介して対向させた。これに電解液を含浸させアルミラミネートフィルムからなる外装に封入して非水系二次電池を作製した。ここで、電解液には１Ｍ ＬｉＰＦ_６エチレンカーボネート／エチルメチルカーボネート（３／７重量比）（キシダ化学社製）を用いた。また、セパレータは前述の実施例１−８，１−９におけるＰＥ微多孔膜を用いた。
この実施例１−１１の電池についても上述したオーブンテスト、サイクル特性、保存テスト、および電池のふくれについて評価した。結果を表３に示す。
［実施例１−１２］
コバルト酸リチウム（ＬｉＣｏＯ_２；日本化学工業社製）粉末８９．５重量部、アセチレンブラック（電気化学工業社製；商品名デンカブラック）４．５重量部、ポリフッ化ビニリデン（クレハ化学社製）６重量部となるようにＮ−メチル−２ピロリドン溶媒を用いてこれらを混練し、スラリーを作製した。得られたスラリーを厚さが２０μｍのアルミ箔上に塗布乾燥後プレスし、１００μｍの正極を得た。
メソフェーズカーボンマイクロビーズ（ＭＣＭＢ：大阪瓦斯化学社製）粉末８７重量部、アセチレンブラック（電気化学工業社製；商品名デンカブラック）３重量部、ポリフッ化ビニリデン（クレハ化学社製）１０重量部となるようにＮ−メチル−２ピロリドン溶媒を用いてこれらを混練し、スラリーを作製した。得られたスラリーを厚さが１８μｍの銅箔上に塗布乾燥後プレスし、９０μｍの負極を得た。
実施例１−４で作製したスラリーを上記の負極表面に塗工し、これを重量比で水：ＤＭＡｃ：ＴＰＧ＝７０：１８：１２（重量比）で３０℃となっている凝固液中に浸漬し、次いで水洗、乾燥を行い、負極表面に厚み３μｍの本発明の電池用多孔膜を形成した。
上記正極及び負極を、セパレータを介して対向させた。これに電解液を含浸させアルミラミネートフィルムからなる外装に封入して非水系二次電池を作製した。ここで、電解液には１Ｍ ＬｉＰＦ_６エチレンカーボネート／エチルメチルカーボネート（３／７重量比）（キシダ化学社製）を用いた。また、セパレータは前述の実施例１−８，１−９におけるＰＥ微多孔膜を用いた。
この実施例１−１２の電池についても上述したオーブンテストサイクル特性、保存テスト、および電池のふくれについて評価した。結果を表３に示す。
［実施例１−１３］
コバルト酸リチウム（ＬｉＣｏＯ_２；日本化学工業社製）粉末８９．５重量部、アセチレンブラック（電気化学工業社製；商品名デンカブラック）４．５重量部、ポリフッ化ビニリデン（クレハ化学社製）６重量部となるようにＮ−メチル−２ピロリドン溶媒を用いてこれらを混練し、スラリーを作製した。得られたスラリーを厚さが２０μｍのアルミ箔上に塗布乾燥後プレスし、１００μｍの正極を得た。
メソフェーズカーボンマイクロビーズ（ＭＣＭＢ：大阪瓦斯化学社製）粉末８７重量部、アセチレンブラック（電気化学工業社製；商品名デンカブラック）３重量部、ポリフッ化ビニリデン（クレハ化学社製）１０重量部となるようにＮ−メチル−２ピロリドン溶媒を用いてこれらを混練し、スラリーを作製した。得られたスラリーを厚さが１８μｍの銅箔上に塗布乾燥後プレスし、９０μｍの負極を得た。
実施例１−４で作製したスラリーを上記の正極および負極表面に塗工し、これを重量比で水：ＤＭＡｃ：ＴＰＧ＝７０：１８：１２（重量比）で３０℃となっている凝固液中に浸漬し、次いで水洗、乾燥を行い、正極および負極表面に厚み３μｍの本発明の電池用多孔膜を形成した。
上記正極及び負極を、セパレータを介して対向させた。これに電解液を含浸させアルミラミネートフィルムからなる外装に封入して非水系二次電池を作製した。ここで、電解液には１Ｍ ＬｉＰＦ_６エチレンカーボネート／エチルメチルカーボネート（３／７重量比）（キシダ化学社製）を用いた。また、セパレータは前述の実施例１−８，１−９におけるＰＥ微多孔膜を用いた。
この実施例１−１３の電池についても上述したオーブンテスト、サイクル特性、保存テスト、および電池のふくれについて評価した。結果を表３に示す。

（２）第三、四の形態に係る実施例
以下、本発明の第三、四の形態に係る実施例について説明する。本実施例で適用した測定方法は以下の通りである。なお、無機フィラーの平均粒子径、比表面積、結晶構造および元素比、ならびに膜厚の測定法については、上述した第一、二の形態に係る実施例の場合と同様である。また、セパレータの破膜テストおよびガス発生量試験についても上述した第一、二の形態に係る実施例の場合と同様である。
［空孔率］
サンプルとなる膜について、それぞれの構成材料の重量（Ｗｉ：ｇ／ｍ^２）を真密度（ｄｉ：ｇ／ｃｍ^３）で割り、これらの和（Σ（Ｗｉ／ｄｉ））を求める。これを膜厚（μｍ）で割り、１から引いた値に１００をかけることで空孔率（％）を算出した。
［ガーレ値］
ＪＩＳ Ｐ８１１７に従い測定した。
［突刺強度］
カトーテック社製ＫＥＳ−Ｇ５ハンディー圧縮試験器を用いて、針先端の曲率半径０．５ｍｍ、突刺速度２ｍｍ／秒の条件で突刺試験を行い、最大突刺荷重を突刺強度とした。ここでサンプルはΦ１１．３ｍｍの穴があいた金枠（試料ホルダー）に挟み固定した。
［シャットダウン特性（ＳＤ特性）］
まず、サンプルとなるセパレータを直径１９ｍｍに打ち抜き、非イオン性界面活性剤（花王社製；エマルゲン２１０Ｐ）の３重量％メタノール溶液中に浸漬して風乾する。そしてセパレータに電解液を含浸させＳＵＳ板（Φ１５．５ｍｍ）に挟んだ。ここで電解液は１Ｍ ＬｉＢＦ_４プロピレンカーボネート／エチレンカーボネート（１／１重量比）を用いた。これを２０３２型コインセルに封入した。コインセルからリード線をとり、熱電対を付けてオーブンの中に入れた。昇温速度１．６℃／分で昇温させ、同時に振幅１０ｍＶ、１ｋＨｚの周波数の交流を印加することでセルの抵抗を測定した。
上記測定で１３５〜１５０℃の範囲で抵抗値が１０^３ｏｈｍ・ｃｍ^２以上となった場合はＳＤ特性を○とし、そうでなかった場合はＳＤ特性を×とした。
［電池保存特性］
以下の実施例および比較例で作製したセパレータを用いて、次のとおり非水系二次電池を作製した。
コバルト酸リチウム（ＬｉＣｏＯ_２；日本化学工業社製）粉末８９．５重量部、アセチレンブラック（電気化学工業社製；商品名デンカブラック）４．５重量部、ポリフッ化ビニリデン（クレハ化学社製）６重量部となるようにＮ−メチル−２ピロリドン溶媒を用いてこれらを混練し、スラリーを作製した。得られたスラリーを厚さが２０μｍのアルミ箔上に塗布乾燥後プレスし、１００μｍの正極を得た。
メソフェーズカーボンマイクロビーズ（ＭＣＭＢ：大阪瓦斯化学社製）粉末８７重量部、アセチレンブラック（電気化学工業社製；商品名デンカブラック）３重量部、ポリフッ化ビニリデン（クレハ化学社製）１０重量部となるようにＮ−メチル−２ピロリドン溶媒を用いてこれらを混練し、スラリーを作製した。得られたスラリーを厚さが１８μｍの銅箔上に塗布乾燥後プレスし、９０μｍの負極を得た。
上記正極及び負極を、以下の実施例および比較例で作製したセパレータを介して対向させた。これに電解液を含浸させアルミラミネートフィルムからなる外装に封入して非水系二次電池を作製した。ここで、電解液には１Ｍ ＬｉＰＦ_６エチレンカーボネート／エチルメチルカーボネート（３／７重量比）（キシダ化学社製）を用いた。
この非水系二次電池について０．２Ｃ ４．２Ｖ ８時間の定電流・定電圧充電、０．２Ｃ、２．７５Ｖカットオフの定電流放電を行った。５サイクル目に得られた放電容量をこのセルの初期容量とした。その後、０．２Ｃ ４．２Ｖ ８時間の定電流・定電圧充電を行い、８５℃にて３日間保存した。そして、０．２Ｃ、２．７５Ｖカットオフの定電流放電を行い、８５℃、３日間保存における残存容量を求めた。残存容量を初期容量で割り１００かけた値を容量維持率とし、この容量維持率を電池の保存特性の指標とした。
［電池の膨れ］
上記の電池の保存特性試験後の各電池を目視で確認して、電池が明らかに膨らんでいたものについては×と判断し、電池の膨みが外観上分からなかったものについては○と判断した。なお、この場合の電池のふくれは、電池内でガスが発生したことによるものである。
［実施例２−１］
ポリエチレンパウダーとしてＴｉｃｏｎａ社製のＧＵＲ２１２６（重量平均分子量４１５万、融点１４１℃）とＧＵＲＸ１４３（重量平均分子量５６万、融点１３５℃）を用いた。ＧＵＲ２１２６とＧＵＲＸ１４３とを１：９（重量比）となるようにして、ポリエチレン濃度が３０重量％となるように流動パラフィン（松村石油研究所社製；スモイルＰ−３５０Ｐ；沸点４８０℃）とデカリンの混合溶媒中に溶解させ、ポリエチレン溶液を作製した。該ポリエチレン溶液の組成はポリエチレン：流動パラフィン：デカリン＝３０：４５：２５（重量比）である。
このポリエチレン溶液を１４８℃でダイから押出し、水浴中で冷却してゲル状テープ（ベーステープ）を作製した。該ベーステープを６０℃で８分、９５℃で１５分乾燥し、該ベーステープを縦延伸、横延伸と逐次行い二軸延伸した。ここで縦延伸は延伸倍率５．５倍、延伸温度９０℃、横延伸は延伸倍率１１．０倍、延伸温度は１０５℃とした。延伸の後に１２５℃で熱固定を行った。次にこれを塩化メチレン浴に浸漬し、流動パラフィンとデカリンを抽出した。その後、５０℃で乾燥し、１２０℃でアニール処理することでポリエチレン微多孔膜を得た。
得られたポリエチレン微多孔膜は目付け４．７ｇ／ｍ^２、膜厚９μｍ、空孔率４５％、ガーレ値１５０秒／１００ｃｃ、突刺強度３００ｇであった。
メタ型全芳香族ポリアミドとしてポリメタフェニレンイソフタルアミドであるコーネックス（登録商標；帝人テクノプロダクツ社製）を用いた。ジメチルアセトアミド（ＤＭＡｃ）：トリプロピレングリコール（ＴＰＧ）＝６０：４０（重量比）にコーネックスが６重量％となるように溶解し、コーネックス溶液を作製した。
多孔質フィラーとして平均粒子径３μｍ、比表面積２９０ｍ^２／ｇのゼオライト（ＨＳＺ−５００ＫＯＡ；東ソー社製）を用いた。ゼオライト：コーネックス＝５０：５０（重量比）となるように該コーネックス溶液に該ゼオライトを分散させ、分散液を調整した。
マイヤーバーを２本対峙させ、その間に該分散液を適量のせた。ポリエチレン微多孔膜を分散液がのっているマイヤーバー間を通過させてポリエチレン微多孔膜の両面に分散液を塗工した。ここでマイヤーバー間のクリアランスは３０μｍ、マイヤーバーの番手は２本と＃６を用いた。これを重量比で水：ＤＭＡｃ：ＴＰＧ＝７０：１８：１２（重量比）で３０℃となっている凝固液中に浸漬し、次いで水洗、乾燥を行い、ポリエチレン微多孔膜の表裏にゼオライトとコーネックスからなる耐熱性多孔質層を形成し、本発明の非水系二次電池用セパレータを得た。得られた非水系二次電池用セパレータの特性は表４，５の通りである。なお、以下の実施例および比較例に係るセパレータの特性についても同様に表４，５に示した。
［実施例２−２］
多孔質フィラーとして平均粒子径２μｍ、比表面積４００ｍ^２／ｇのゼオライト（ＨＳＺ−９８０ＨＯＡ；東ソー社製）を用いた点以外は、実施例２−１と同様にして、本発明の非水系二次電池用セパレータを得た。
［実施例２−３］
多孔質フィラーとして平均粒子径４μｍ、比表面積７００ｍ^２／ｇのゼオライト（ＨＳＺ−３４１ＮＨＡ；東ソー社製）を用いた点以外は、実施例２−１と同様にして、本発明の非水系二次電池用セパレータを得た。
［実施例２−４］
活性炭（関西熱化学社製；ＭＳＰ−２０）を、ジメチルアセトアミド（ＤＭＡｃ）を分散溶剤とした湿式粉砕（２ｍｍ径のジルコニアビーズミル）を行うことで、平均粒子径０．６μｍ、比表面積１６００ｍ^２／ｇの活性炭を得た。この活性炭を多孔質フィラーとして用いた点以外は、実施例２−１と同様にして、本発明の非水系二次電池用セパレータを得た。
［実施例２−５］
多孔質フィラーとして平均粒子径１．４μｍ、比表面積１９０ｍ^２／ｇの活性アルミナ（住友化学社製；ＫＣ−５０１）を用いた点以外は、実施例２−１と同様にして、本発明の非水系二次電池用セパレータを得た。
［実施例２−６］
水酸化アルミニウム（昭和電工製；Ｈ−４３Ｍ）を２２０℃で熱処理し、平均粒子径０．８μｍ、比表面積６０ｍ^２／ｇの活性アルミナを得た。なお、この活性アルミナの結晶構造についてＸＲＤで解析したところ、アモルファス構造に由来するブロードなピークは確認されず、ギブサイトに由来するピークが明確に観察されたため、バルク構造は主にギブサイトであり、アモルファスアルミナではないことが分かった。
この活性アルミナを多孔質フィラーとして用いた点以外は、実施例２−１と同様にして、本発明の非水系二次電池用セパレータを得た。
［実施例２−７］
水酸化アルミニウム（昭和電工製；Ｈ−４３Ｍ）を２８０℃で熱処理し、平均粒子径０．８μｍ、比表面積４００ｍ^２／ｇの活性アルミナを得た。この活性アルミナについてＸＲＤ解析を行ったところ、ブロードなチャートの中にベーマイトに由来するピークが極僅かに観察され、２θ＝１４．３９°のピークの積分強度が９８ｃｐｓ・ｄｅｇであり、このメインピークの積分強度は２θ＝１０〜６０ｄｅｇにかけて存在するブロードなピークの積分強度に対して０．０７であった。よって、この活性アルミナは、主にアモルファス状のバルク構造で、極僅かにベーマイト相が混在していたことから、アモルファスアルミナとも言える。また、この活性アルミナの表面における０／Ａｌの元素比は１．５４であった。
この活性アルミナを多孔質フィラーとして用いた点以外は、実施例２−１と同様にして、本発明の非水系二次電池用セパレータを得た。
［実施例２−８］
ポリエチレン微多孔膜の片面のみに分散液を塗工し多孔質層を形成した点以外は、実施２−７と同様にして、本発明の非水系二次電池用セパレータを得た。
［比較例２−１］
実施例２−１で用いた多孔質フィラーのかわりに、無機フィラーとして平均粒子径０．６μｍ、比表面積６ｍ^２／ｇのα−アルミナ（昭和電工製：ＡＬ１６０ＳＧ−３）を適用した点以外は、実施例２−１と同様にして、非水系二次電池用セパレータを作製した。
［比較例２−２］
実施例１で用いた多孔質フィラーのかわりに、無機フィラーとして平均粒子径０．６μｍ、比表面積１５ｍ^２／ｇのベーマイト（大明化学工業社製：Ｃ０６）を適用した点以外は、実施例２−１と同様にして、非水系二次電池用セパレータを作製した。
［比較例２−３］
水酸化アルミニウム（昭和電工製；Ｈ−４３Ｍ）を２０５℃で熱処理し、平均粒子径０．８μｍ、比表面積３０ｍ^２／ｇの活性アルミナを得た。なお、この活性アルミナの結晶構造についてＸＲＤで解析したところ、アモルファス構造に由来するブロードなピークは確認されず、ギブサイトに由来するピークが明確に観察されたため、バルク構造は主にギブサイトであり、アモルファスアルミナではないことが分かった。多孔質フィラーをこの活性アルミナに変更した点以外は、実施例２−１と同様にして、非水系二次電池用セパレータを得た。
［比較例２−４］
ポリエチレンパウダーとしてＴｉｃｏｎａ社製のＧＵＲ２１２６（重量平均分子量４１５万、融点１４１℃）とＧＵＲＸ１４３（重量平均分子量５６万、融点１３５℃）を用いた。ＧＵＲ２１２６とＧＵＲＸ１４３とを１：９（重量比）となるようにして、ポリエチレン濃度が１５重量％となるように流動パラフィン（松村石油研究所社製；スモイルＰ−３５０Ｐ；沸点４８０℃）とデカリンの混合溶媒中に溶解させ、ポリエチレン溶液を作製した。該ポリエチレン溶液の組成はポリエチレン：流動パラフィン：デカリン＝３０：４５：２５（重量比）である。
該ポリエチレン溶液中に重量比でポリエチレン：ゼオライト（ＨＳＺ−５００ＫＯＡ；東ソー社製）＝５０：５０となるように分散させスラリーを作製した。ここで、このゼオライトは平均粒子径３μｍ、比表面積２９０ｍ^２／ｇである。
このスラリーを１４８℃でダイから押出し、水浴中で冷却してゲル状テープ（ベーステープ）を作製した。該ベーステープを６０℃で８分、９５℃で１５分乾燥し、該ベーステープを縦延伸、横延伸と逐次行い二軸延伸した。ここで縦延伸は延伸倍率５．５倍、延伸温度９０℃、横延伸は延伸倍率１１．０倍、延伸温度は１０５℃とした。延伸の後に１２５℃で熱固定を行った。次にこれを塩化メチレン浴に浸漬し、流動パラフィンとデカリンを抽出した。その後、５０℃で乾燥し、１２０℃でアニール処理することで多孔質フィラーを含むポリエチレン微多孔膜（非水系二次電池用セパレータ）を得た。
［比較例２−５］
メタ型全芳香族ポリアミドとしてポリメタフェニレンイソフタルアミドであるコーネックス（登録商標；帝人テクノプロダクツ社製）を用いた。ジメチルアセトアミド（ＤＭＡｃ）：トリプロピレングリコール（ＴＰＧ）＝６０：４０（重量比）にコーネックスが６重量％となるように溶解し、コーネックス溶液を作製した。
マイヤーバーを２本対峙させ、その間に該コーネックス溶液を適量のせた。比較例２−４で作製した多孔質フィラーを含むポリエチレン微多孔膜をコーネックス溶液がのっているマイヤーバー間を通過させてポリエチレン微多孔膜の両面にコーネックス溶液を塗工した。ここでマイヤーバー間のクリアランスは３０μｍ、マイヤーバーの番手は２本とも＃６を用いた。これを重量比で水：ＤＭＡｃ：ＴＰＧ＝７０：１８：１２（重量比）で３０℃となっている凝固液中に浸漬し、次いで水洗、乾燥を行い、多孔質フィラーを含むポリエチレン微多孔膜の表裏にコーネックスからなる多孔質層を形成し、非水系二次電池用セパレータを得た。

［サイクル特性評価］
次に、耐熱性多孔質層を多孔質基材の片面あるいは両面に形成したセパレータについて、以下の通り非水系二次電池を作製し、サイクル特性に違いがあるかどうか検討した。
コバルト酸リチウム（ＬｉＣｏＯ_２；日本化学工業社製）粉末８９．５重量部、アセチレンブラック（電気化学工業社製；商品名デンカブラック）４．５重量部、ポリフッ化ビニリデン（クレハ化学社製）６重量部となるようにＮ−メチル−２ピロリドン溶媒を用いてこれらを混練し、スラリーを作製した。得られたスラリーを厚さが２０μｍのアルミ箔上に塗布乾燥後プレスし、１００μｍの正極を得た。
メソフェーズカーボンマイクロビーズ（ＭＣＭＢ：大阪瓦斯化学社製）粉末８７重量部、アセチレンブラック（電気化学工業社製；商品名デンカブラック）３重量部、ポリフッ化ビニリデン（クレハ化学社製）１０重量部となるようにＮ−メチル−２ピロリドン溶媒を用いてこれらを混練し、スラリーを作製した。得られたスラリーを厚さが１８μｍの銅箔上に塗布乾燥後プレスし、９０μｍの負極を得た。
上記正極及び負極を、セパレータを介して対向させた。これに電解液を含浸させアルミラミネートフィルムからなる外装に封入して非水系二次電池を作製した。ここで、電解液には１Ｍ ＬｉＰＦ_６エチレンカーボネート／エチルメチルカーボネート（３／７重量比）（キシダ化学社製）を用いた。
ここでセパレータは実施例２−７と実施例２−８のものを用い、表６に示す実施例２−９〜２−１１の電池を作製した。
サイクル特性の評価は１Ｃ ４．２Ｖ ２時間の定電流・定電圧充電、１Ｃ、２．７５Ｖカットオフの定電流放電にて充放電を行い、１サイクル目の容量を基準としたときの３００サイクル目の容量維持率をサイクル特性の指標とした。なお、測定時の温度は３０℃とした。結果を表６に示す。

表６の結果より、耐熱性多孔質層を多孔質基材の両面に形成した構成の方が、片面の構成よりも容量維持率に優れていることが分かった。また、片面の構成でもポリエチレン微多孔膜を負極側に配置した方が容量維持率が高くなることが分かった。
（３）第三の形態における特殊な活性アルミナの効果について
以下、本発明の第三の形態のうち、比表面積が３００〜１０００ｍ^２／ｇの活性アルミナを用いた構成について検討する。
以下の実施例で適用した測定方法は次の通りである。なお、無機フィラーの平均粒子径、比表面積、結晶構造および元素比の測定法については、上述した第一、二の形態に係る実施例の場合と同様である。
［アルミナの真密度の測定］
以下の実施例および比較例で使用したアルミナについて、真密度をマイクロウルトラピクノメータ（ユアサアイオニクス製 ＭＵＰＹ−２１Ｔ）により求めた。また、測定にはヘリウムガスを利用した。
［実施例３−１］
（ｉ） ＰＥ微多孔膜の製造
ポリエチレンパウダーとして、Ｔｉｃｏｎａ社製のＧＵＲ２１２６（重量平均分子量４１５万、融点１４１℃）とＧＵＲＸ１４３（重量平均分子量５６万、融点１３５℃）を用いた。ＧＵＲ２１２６とＧＵＲＸ１４３を、１：９（重量比）となるようにして、ポリエチレン濃度が３０重量％となるように流動パラフィン（松村石油研究所社製；スモイルＰ−３５０Ｐ；沸点４８０℃）とデカリンの混合溶媒中に溶解させて、ポリエチレン溶液を作製した。このポリエチレン溶液の組成は、ポリエチレン：流動パラフィン：デカリン＝３０：４５：２５（重量比）であった。
このポリエチレン溶液を１４８℃でダイから押し出し、水浴中で冷却してゲル状テープ（ベーステープ）を作製した。このベーステープを６０℃で８分、９５℃で１５分乾燥し、次いで、ベーステープを縦延伸、横延伸と逐次行う２軸延伸にて延伸した。ここで、縦延伸は５．５倍、延伸温度は９０℃、横延伸は延伸倍率１１．０倍、延伸温度は１０５℃とした。横延伸の後に１２５℃で熱固定を行った。次にこれを塩化メチレン浴に浸漬し、流動パラフィンとデカリンを抽出した。その後、５０℃で乾燥し、１２０℃でアニール処理して、ＰＥ微多孔膜を得た。
（ｉｉ） ポリメタフェニレンイソフタルアミドの製造
温度計、撹拌装置及び原料投入口を備えた反応容器に、水分率が１００ｐｐｍ以下のＮＭＰ７５３ｇを入れ、このＮＭＰ中にメタフェニレンジアミン８５．２ｇとアニリン０．５ｇを溶解し、０℃に冷却した。この冷却したジアミン溶液にイソフタル酸クロライド１６０．５ｇを撹拌しながら徐々に添加し反応させた。この反応で溶液の温度は７０℃に上昇した。粘度変化が止まった後、水酸化カルシウム粉末を５８．４ｇ添加し、さらに４０分間撹拌して反応を終了させて重合溶液を取り出し、水中で再沈殿させポリメタフェニレンイソフタルアミドを１８４．０ｇ得た。
（ｉｉｉ） 活性アルミナの製造
水酸化アルミニウム（昭和電工製；Ｈ−４３Ｍ）を２８０℃で熱処理し、平均粒子径０．８μｍ、比表面積４００ｍ^２／ｇの活性アルミナを得た。この活性アルミナの真密度は３．１ｇ／ｃｍ^２であった。また、ＸＲＤ解析を行ったところ、ブロードなチャートの中にベーマイトに由来するピークが極僅かに観察され、２θ＝１４．３９°のピークの積分強度が９８ｃｐｓ・ｄｅｇであり、このメインピークの積分強度は２θ＝１０〜６０ｄｅｇにかけて存在するブロードなピークの積分強度に対して０．０７であった。よって、この活性アルミナは、主にアモルファス状のバルク構造で、極僅かにベーマイト相が混在していたことから、アモルファスアルミナとも言える。
（ｉｖ） 積層セパレータの製造
上記のようにして得られたポリメタフェニレンイソフタルアミドと活性アルミナとが、重量比で４０：６０となるように調製し、これらをポリメタフェニレンイソフタルアミド濃度が５．５重量％となるように、ジメチルアセトアミド（ＤＭＡｃ）とトリプロピレングリコール（ＴＰＧ）が重量比５０：５０となっている混合溶媒に混合し、塗工用スラリーを得た。
マイヤーバーに上記塗工用スラリーを適量のせ、一対のマイヤーバー間に上記のようにして得たＰＥフィルムを通すことでＰＥフィルムの両面に塗工用スラリーを塗工した。これを、重量比で水：ＤＭＡｃ：ＴＰＧ ＝ ５０：２５：２５で４０℃となっている凝固液中に浸漬した。その後、得られたフィルムを水洗・乾燥した。これにより、耐熱性多孔質層が塗工された積層セパレータを得た。
（ｖ） 正極の製造
コバルト酸リチウム（ＬｉＣｏＯ_２、日本化学工業社製）粉末８９．５重量部と、アセチレンブラック（デンカブラック、電気化学工業社製）４．５重量部及びポリフッ化ビニリデン（クレア化学工業株式会社製）の乾燥重量が６重量部となるように、６重量％のポリフッ化ビニリデンのＮＭＰ溶液を用い、正極剤ペーストを作製した。得られたペーストを、厚さ２０μｍのアルミ箔上に塗布乾燥後プレスして、厚さ９７μｍの正極を得た。
（ｖｉ） 負極の製造
負極活物質としてメソフェーズカーボンマイクロビーズ（ＭＣＭＢ、大阪瓦斯化学社製）粉末８７重量部と、アセチレンブラック３重量部及びポリフッ化ビニリデンの乾燥重量が１０重量部となるように、６重量％のポリフッ化ビニリデンのＮＭＰ溶液を用い、負極剤ペーストを作製した。得られたペーストを、厚さ１８μｍの銅箔上に塗布乾燥後プレスして、厚さ９０μｍの負極を作製した。
（ｖｉｉ） 非水電解質の調製
エチレンカーボネートとエチルメチルカーボネートを３：７の重量比で混合した溶液に、ＬｉＰＦ_６が１ｍｏｌ／Ｌとなるように溶解したものを用いた。
（ｖｉｉｉ） 非水系二次電池の製造
上記のようにして得られた正極及び負極を積層セパレータを介して対向させた。これに非水電解質を含浸させ、アルミラミネートフィルムからなる外装に封入して、非水系二次電池を作製した。
［比較例３−１］
ポリエチレンパウダーとして、Ｔｉｃｏｎａ社製のＧＵＲ２１２６（重量平均分子量４１５万、融点１４１℃）とＧＵＲＸ１４３（重量平均分子量５６万、融点１３５℃）を用いた。ＧＵＲ２１２６とＧＵＲＸ１４３を、１：９（重量比）となるようにして、ポリエチレン濃度が３０重量％となるように流動パラフィン（松村石油研究所社製；スモイルＰ−３５０Ｐ；沸点４８０℃）とデカリンの混合溶媒中に溶解させ、さらにフィラーとして平均粒子径０．５μｍ、比表面積７ｍ^２／ｇのα−アルミナ（ＡＬ−１６０ＳＧ−３；昭和電工製）を分散させ、ポリエチレン溶液を作製した。このポリエチレン溶液の組成は、ポリエチレン：アルミナ：流動パラフィン：デカリン＝３０：１０：５５：３０（重量比）であった。
このポリエチレン溶液を１４８℃でダイから押し出し、水浴中で冷却してゲル状テープ（ベーステープ）を作製した。このベーステープを６０℃で８分、９５℃で１５分乾燥し、次いで、ベーステープを縦延伸、横延伸と逐次行う２軸延伸にて延伸した。ここで、縦延伸は５．５倍、延伸温度は９０℃、横延伸は延伸倍率１１．０倍、延伸温度は１０５℃とした。横延伸の後に１２５℃で熱固定を行った。次にこれを塩化メチレン浴に浸漬し、流動パラフィンとデカリンを抽出した。その後、５０℃で乾燥し、１２０℃でアニール処理し、ＰＥ微多孔膜からなるセパレータを得た。
このセパレータを用いた以外は、実施例３−１と同様にして非水系二次電池を作製した。
［比較例３−２］
水酸化アルミニウム（昭和電工製；Ｈ−４３Ｍ）を２２０℃で熱処理し、平均粒子径０．８μｍ、比表面積６０ｍ^２／ｇの活性アルミナを得た。この活性アルミナの真密度は２．５ｇ／ｃｍ^２であった。また、ＸＲＤではアモルファス構造に由来するブロードなピークは確認されず、ギブサイトに由来するピークが明確に観察されたため、この活性アルミナのバルク構造は主にギブサイトであった。
この活性アルミナを無機フィラーとして用いた以外は、比較例３−１と同様にして、非水系二次電池を得た。
［比較例３−３］
水酸化アルミニウム（昭和電工製；Ｈ−４３Ｍ）を２４０℃で熱処理し、平均粒子径０．８μｍ、比表面積２００ｍ^２／ｇの活性アルミナを得た。この活性アルミナの真密度は２．６ｇ／ｃｍ^２であった。また、この活性アルミナについてＸＲＤ解析を行ったところ、ギブサイトに由来するピークが観察され、２θ＝１８．２７°のピークの積分強度が３７１ｃｐｓ・ｄｅｇであり、このメインピークの積分強度は２θ＝１０〜６０ｄｅｇにかけて存在するブロードなピークの積分強度に対して０．３５であった。よって、この活性アルミナのバルク構造は主としてギブサイトであった。
この活性アルミナを無機フィラーとして用いた以外は、比較例３−１と同様にして、非水系二次電池を得た。
［比較例３−４］
無機フィラーとして平均粒子径２μｍ、比表面積４００ｍ^２／ｇのゼオライト（ＨＳＺ−９８０ＨＯＡ；東ソー社製）を用いた以外は、比較例３−１と同様にして、非水系二次電池を得た。
［比較例３−５］
無機フィラーとして平均粒子径２μｍ、比表面積３００ｍ^２／ｇのシリカ（東海化学工業所製；ＭＬ−３８４）を用いた以外は、比較例３−１と同様にして、非水系二次電池を得た。
［比較例３−６］
活性炭（関西熱化学社製；ＭＳＰ−２０）を、ジメチルアセトアミド（ＤＭＡｃ）を分散溶剤とした湿式粉砕（２ｍｍ径のジルコニアビーズミル）を行うことで、平均粒子径０．６μｍ、比表面積１６００ｍ^２／ｇの活性炭を得た。
この活性炭を無機フィラーとして用いた以外は、比較例３−１と同様にして、非水系二次電池を得た。
［容量維持率の測定］
上記のようにして作製した実施例および比較例の非水系二次電池について、６０℃の恒温槽中において、充放電測定装置（北斗電工社製 ＨＪ−１０１ＳＭ６）を使用し、充放電特性を測定した。充放電条件について、充電は０．２Ｃで４．２Ｖまで８時間充電を行い、放電については０．２Ｃで２．７５Ｖまで放電を行い、容量維持率は初期放電容量に対する５００サイクル時点での放電容量の割合とした。測定結果を表７に示す。

表７から分かるように、比表面積が３００〜１０００ｍ^２／ｇの活性アルミナを用いた実施例３−１は、比表面積が上記範囲外である活性アルミナ（比較例３−２，３−３）や、α−アルミナ（比較例３−１）、その他の多孔質フィラー（比較例３−３〜３−６）に比べて５００回のサイクル特性試験後の容量維持率が格段に優れている。これは比表面積が３００〜１０００ｍ^２／ｇの活性アルミナが電池内のＨＦの活性を低下させたためと考えられる。なお、実施例では複合セパレータにおける耐熱性多孔質層中にフィラーが適用されており、比較例ではＰＥセパレータ中にフィラーが適用されたという相違点はあるものの、両者はセパレータ中にフィラーを適用したという点で一致しており、上記の相違点が容量維持率に与える影響はさほど大きくない。
（４）第四の形態におけるアモルファスアルミナの効果について
以下、本発明の第四の形態のうち、アモルファスアルミナを用いた構成について検討する。各種測定方法については上述した通りである。
［実施例４−１］
上述した実施例３−１と同様にして、実施例４−１の非水系二次電池を作製した。
［比較例４−１］
ポリエチレンパウダーとして、Ｔｉｃｏｎａ社製のＧＵＲ２１２６（重量平均分子量４１５万、融点１４１℃）とＧＵＲＸ１４３（重量平均分子量５６万、融点１３５℃）を用いた。ＧＵＲ２１２６とＧＵＲＸ１４３を、１：９（重量比）となるようにして、ポリエチレン濃度が３０重量％となるように流動パラフィン（松村石油研究所社製；スモイルＰ−３５０Ｐ；沸点４８０℃）とデカリンの混合溶媒中に溶解させ、さらにフィラーとして平均粒子径０．５μｍ、比表面積７ｍ^２／ｇのα−アルミナ（ＡＬ−１６０ＳＧ−３；昭和電工製）を分散させ、ポリエチレン溶液を作製した。このポリエチレン溶液の組成は、ポリエチレン：アルミナ：流動パラフィン：デカリン＝３０：１０：５５：３０（重量比）であった。
このポリエチレン溶液を１４８℃でダイから押し出し、水浴中で冷却してゲル状テープ（ベーステープ）を作製した。このベーステープを６０℃で８分、９５℃で１５分乾燥し、次いで、ベーステープを縦延伸、横延伸と逐次行う２軸延伸にて延伸した。ここで、縦延伸は５．５倍、延伸温度は９０℃、横延伸は延伸倍率１１．０倍、延伸温度は１０５℃とした。横延伸の後に１２５℃で熱固定を行った。次にこれを塩化メチレン浴に浸漬し、流動パラフィンとデカリンを抽出した。その後、５０℃で乾燥し、１２０℃でアニール処理し、ＰＥ微多孔膜からなるセパレータを得た。
このセパレータを用いた以外は、上述した実施例３−１と同様にして非水系二次電池を作製した。
［比較例４−２］
無機フィラーとして平均粒子径０．６μｍ、比表面積１５ｍ^２／ｇの非多孔質のアルミナ（大明化学工業製； Ｃ０６）を用いた以外は、比較例４−１と同様にして、非水系二次電池を得た。なお、このアルミナについてＸＲＤ解析を行ったところ、ベーマイトに由来する明確なピークが観察された。
［比較例４−３］
無機フィラーとして平均粒子径０．８μｍ、比表面積７ｍ^２／ｇの非多孔質の水酸化アルミニウム（昭和電工製； Ｈ−４３Ｍ）を用いた以外は、比較例４−１と同様にして、非水系二次電池を得た。なお、この水酸化アルミニウムについてＸＲＤ解析を行ったところ、ギブサイトに由来する明確なピークが観察された。
［容量維持率の測定］
上記のようにして作製した実施例および比較例の非水系二次電池について、６０℃の恒温槽中において、充放電測定装置（北斗電工社製 ＨＪ−１０１ＳＭ６）を使用し、充放電特性を測定した。充放電条件について、充電は０．２Ｃで４．２Ｖまで８時間充電を行い、放電については０．２Ｃで２．７５Ｖまで放電を行い、容量維持率は初期放電容量に対する４００サイクル時点での放電容量の割合とした。測定結果を表８に示す。

表８から分かるように、アモルファスアルミナを用いた実施例４−１は、α−アルミナ（比較例４−１）やベーマイト（比較例４−２）、ギブサイト（比較例４−３）等の他のアルミナ系フィラーに比べて４００回のサイクル特性試験後の容量維持率が格段に優れている。これはアモルファスアルミナが電池内のＨＦの活性を低下させたためと考えられる。
（５）第五の形態に係る実施例
以下、本発明の第五の形態に係る実施例について説明する。なお、無機フィラーの平均粒子径、比表面積、真密度、結晶構造および元素比、ならびに膜厚の測定法については、上述した通りである。
［実施例５−１］
（ｉ） 活性アルミナの製造
上述した実施例３−１と同様にして活性アルミナＡを製造した。
（ｉｉ） 正極、負極、非水電解質の製造
正極、負極、非水電解質についても上述した実施例３−１と同様にして製造した。
（ｉｉｉ） セパレータの製造
ポリエチレンパウダーとして、Ｔｉｃｏｎａ社製のＧＵＲ２１２６（重量平均分子量４１５万、融点１４１℃）とＧＵＲＸ１４３（重量平均分子量５６万、融点１３５℃）を用いた。ＧＵＲ２１２６とＧＵＲＸ１４３を、１：９（重量比）となるようにして、ポリエチレン濃度が３０重量％となるように流動パラフィン（松村石油研究所社製；スモイルＰ−３５０Ｐ；沸点４８０℃）とデカリンの混合溶媒中に溶解させ、さらに無機フィラーとして上記の活性アルミナＡを分散させ、ポリエチレン溶液を作製した。このポリエチレン溶液の組成は、ポリエチレン：無機フィラー：流動パラフィン：デカリン＝３０：１０：５５：３０（重量比）であった。
このポリエチレン溶液を１４８℃でダイから押し出し、水浴中で冷却してゲル状テープ（ベーステープ）を作製した。このベーステープを６０℃で８分、９５℃で１５分乾燥し、次いで、ベーステープを縦延伸、横延伸と逐次行う２軸延伸にて延伸した。ここで、縦延伸は５．５倍、延伸温度は９０℃、横延伸は延伸倍率１１．０倍、延伸温度は１０５℃とした。横延伸の後に１２５℃で熱固定を行った。次にこれを塩化メチレン浴に浸漬し、流動パラフィンとデカリンを抽出した。その後、５０℃で乾燥し、１２０℃でアニール処理し、ポリエチレン微多孔膜からなるＰＥセパレータを得た。
（ｉｖ） 非水系二次電池
上記のようにして得られた正極及び負極をセパレータを介して対向させた。これに非水電解質を含浸させ、アルミラミネートフィルムからなる外装に封入して、本発明の実施例の非水系二次電池を作製した。
［実施例５−２］
水酸化アルミニウム（昭和電工製；Ｈ−４３Ｍ）を２６０℃で熱処理し、平均粒子径０．８μｍ、比表面積３５０ｍ^２／ｇ、真密度３．０ｇ／ｃｍ^３の活性アルミナＢを得た。この活性アルミナＢについてＸＲＤで構造解析したところ、ブロードなチャートの中にベーマイトに由来するピークが僅かに観察され、２θ＝１４．４０°のピークの積分強度が８３ｃｐｓ・ｄｅｇであり、このメインピークの積分強度は２θ＝１０〜６０ｄｅｇにかけて存在するブロードなピークの積分強度に対して０．０５であった。よって、この活性アルミナは、主にアモルファス状のバルク構造で、極僅かにベーマイト相が混在していた。
この活性アルミナＢを無機フィラーとして用いた点以外は、実施例５−１と同様にして、本発明の非水系二次電池を得た。
［実施例５−３］
フッ化ビニリデン：ヘキサフルオロプロピレン：クロロトリフルオロエチレン＝９７：１：２のモル比で共重合したポリマー（重量平均分子量４０００００）と、上記の活性アルミナＡと、ジメチルアセトアミド（ＤＭＡｃ）と、そしてトリプロピレングリコール（ＴＰＧ）の重量比がポリマー：活性アルミナ：ＤＭＡｃ：ＴＰＧ＝１２：４：４９：３５となるよう十分に攪拌し、ドープを得た。そして、ＰＥＴ短繊維とポリオレフィンの短繊維からなる不織布に上記ドープを十分含浸させ、これを凝固浴中で凝固後、水洗・乾燥を行った。これにより、ポリフッ化ビニリデンと不織布の複合セパレータ（ＰＶｄＦ／不織布セパレータ）を得た。なお、凝固浴の組成は重量比で水：ジメチルアセトアミド：トリプロピレングリコール＝５７：３０：１３とした。そして、ＰＥセパレータの代わりにＰＶｄＦ／不織布セパレータを用いた以外は、実施例５−１と同様にして、本発明の非水系二次電池を得た。
［実施例５−４］
ポリフッ化ビニリデンを５重量部、活性アルミナＡを１重量部、ＤＭＡｃを９４重量部の組成比率で混合し、均一溶液になるように十分に攪拌し、コーティング液を作製した。そして、ポリプロピレンセパレータ（セルガード♯２４００）の片面に、上記のコーティング液をバーコーターにより塗布した後、これを６０℃で乾燥した。これにより、厚み４μｍのコーティング層を持つポリプロピレンセパレータ（ＰＶｄＦ／ＰＰセパレータ）を得た。そして、ＰＥセパレータの代わりにコーティング層を正極と接するようにＰＶｄＦ／ＰＰセパレータを用いた以外は、実施例５−１と同様にして、本発明の非水系二次電池を得た。
［実施例５−５］
実施例５−４で得たＰＶｄＦ／ＰＰセパレータをコーティング層が負極と接するように用いた以外は、実施例５−４と同様にして、本発明の非水系二次電池を得た。
［実施例５−６］
マンガン酸リチウム（ＬｉＭｎ_２Ｏ_４、日揮化学社製）粉末８９．５重量部と、アセチレンブラック（デンカブラック、電気化学工業社製）４．５重量部及びポリフッ化ビニリデン（クレア化学工業株式会社製）の乾燥重量が６重量部となるように、６重量％のポリフッ化ビニリデンのＮＭＰ溶液を用い、正極剤ペーストを作製した。得られたペーストを、厚さ２０μｍのアルミ箔上に塗布乾燥後プレスして、厚さ７０μｍの正極を得た。
この正極を用いた以外は、実施例５−１と同様にして、本発明の非水系二次電池を得た。
［実施例５−７］
コバルト酸リチウム（ＬｉＣｏＯ_２、日本化学工業社製）粉末８９．５重量部と、アセチレンブラック（デンカブラック、電気化学工業社製）４．５重量部と、活性アルミナＡ３重量部及びポリフッ化ビニリデン（クレア化学工業株式会社製）の乾燥重量が６重量部となるように、６重量％のポリフッ化ビニリデンのＮＭＰ溶液を用い、正極剤ペーストを作製した。得られたペーストを、厚さ２０μｍのアルミ箔上に塗布乾燥後プレスして、厚さ９７μｍの正極を得た。
ポリエチレンパウダーとして、Ｔｉｃｏｎａ社製のＧＵＲ２１２６（重量平均分子量４１５万、融点１４１℃）とＧＵＲＸ１４３（重量平均分子量５６万、融点１３５℃）を用いた。ＧＵＲ２１２６とＧＵＲＸ１４３を、１：９（重量比）となるようにして、ポリエチレン濃度が３０重量％となるように流動パラフィン（松村石油研究所社製；スモイルＰ−３５０Ｐ；沸点４８０℃）とデカリンの混合溶媒中に溶解させて、ポリエチレン溶液を作製した。このポリエチレン溶液の組成は、ポリエチレン：流動パラフィン：デカリン＝３０：４５：２５（重量比）であった。
このポリエチレン溶液を１４８℃でダイから押し出し、水浴中で冷却してゲル状テープ（ベーステープ）を作製した。このベーステープを６０℃で８分、９５℃で１５分乾燥し、次いで、ベーステープを縦延伸、横延伸と逐次行う２軸延伸にて延伸した。ここで、縦延伸は５．５倍、延伸温度は９０℃、横延伸は延伸倍率１１．０倍、延伸温度は１０５℃とした。横延伸の後に１２５℃で熱固定を行った。次にこれを塩化メチレン浴に浸漬し、流動パラフィンとデカリンを抽出した。その後、５０℃で乾燥し、１２０℃でアニール処理し、ポリエチレン微多孔膜からなるＰＥセパレータを得た。
上記のようにして作製した正極およびＰＥセパレータを用いた以外は、実施例５−１と同様にして、本発明の非水系二次電池を得た。
［実施例５−８］
負極活物質としてメソフェーズカーボンマイクロビーズ（ＭＣＭＢ、大阪瓦斯化学社製）粉末８７重量部と、アセチレンブラックが３重量部と活性アルミナＡが３重量部とポリフッ化ビニリデンの乾燥重量が１０重量部となるように、６重量％のポリフッ化ビニリデンのＮＭＰ溶液を用い、負極剤ペーストを作製した。得られたペーストを、厚さ１８μｍの銅箔上に塗布乾燥後プレスして、厚さ９１μｍの負極を作製した。
この負極を用い、かつ、実施例５−７におけるＰＥセパレータを用いた以外は、実施例５−１と同様にして、本発明の非水系二次電池を得た。
［実施例５−９］
実施例５−４で調製したコーティング液を、実施例５−１で製造した正極の活物質側にバーコーターを用いて塗布した後、これを６０℃で乾燥した。これにより、厚み４μｍのコーティング層（正極表面層）を持つ正極を得た。
この正極を用い、かつ、実施例５−７におけるＰＥセパレータを用いた以外は、実施例５−１と同様にして、本発明の非水系二次電池を得た。
［実施例５−１０］
実施例５−４で調製したコーティング液を、実施例５−１で製造した負極の活物質側にバーコーターを用いて塗布した後、これを６０℃で乾燥した。これにより、厚み４μｍのコーティング層（負極表面層）を持つ負極を得た。
この負極を用い、かつ、実施例５−７におけるＰＥセパレータを用いた以外は、実施例５−１と同様にして、本発明の非水系二次電池を得た。
［比較例５−１］
実施例５−７におけるＰＥセパレータを用いた以外は、実施例５−１と同様にして、非水系二次電池を得た。
［比較例５−２］
フッ化ビニリデン：ヘキサフルオロプロピレン：クロロトリフルオロエチレン＝９７：１：２のモル比で共重合したポリマー（重量平均分子量４０００００）と、ジメチルアセトアミド（ＤＭＡｃ）と、トリプロピレングリコール（ＴＰＧ）との重量比がポリマー：ＤＭＡｃ：ＴＰＧ＝１２：４８：４０となるよう十分に攪拌し、ドープを得た。そして、ＰＥＴ短繊維とポリオレフィンの短繊維からなる不織布に上記のドープを十分含浸させ、これを凝固浴中で凝固した後、水洗・乾燥を行った。これにより、ポリフッ化ビニリデンが不織布に複合化されたセパレータ（ＰＶｄＦ／不織布セパレータ）を得た。なお、凝固浴の組成は重量比で水：ジメチルアセトアミド：トリプロピレングリコール＝５７：３０：１３とした。
このＰＶｄＦ／不織布セパレータを用いた以外は、実施例５−１と同様にして、非水系二次電池を得た。
［比較例５−３］
ＰＥセパレータの代わりに、ポリプロピレンセパレータ（セルガード♯２４００）を用いた以外は、比較例１と同様にして、非水系二次電池用を得た。
［比較例５−４］
無機フィラーとして平均粒子径０．５μｍ、比表面積７ｍ^２／ｇのα−アルミナ（ＡＬ−１６０ＳＧ−３；昭和電工製）を用いた以外は、実施例５−１と同様にして、非水系二次電池を得た。
［比較例５−５］
水酸化アルミニウム（昭和電工製；Ｈ−４３Ｍ）を２２０℃で熱処理し、平均粒子径０．８μｍ、比表面積６０ｍ^２／ｇ、真密度２．５ｇ／ｃｍ^３の活性アルミナＣを得た。この活性アルミナＣの結晶構造をＸＲＤで解析したところ、アモルファス構造に由来するブロードなピークは確認されず、ギブサイトに由来するピークが明確に観察されたため、活性アルミナＣのバルク構造は主にギブサイトであることが分かった。
この活性アルミナＣを無機フィラーとして用いた以外は、実施例５−１と同様にして、非水系二次電池を得た。
［比較例５−６］
水酸化アルミニウム（昭和電工製；Ｈ−４３Ｍ）を２４０℃で熱処理し、平均粒子径０．８μｍ、比表面積２００ｍ^２／ｇ、真密度２．６ｇ／ｃｍ^３の活性アルミナＤを得た。この活性アルミナＤの結晶構造をＸＲＤで解析したところ、ギブサイトに由来するピークが観察され、２θ＝１８．２７°のピークの積分強度が３７１ｃｐｓ・ｄｅｇであり、このメインピークの積分強度は２θ＝１０〜６０ｄｅｇにかけて存在するブロードなピークの積分強度に対して０．３５であった。よって、活性アルミナＤはバルク構造にギブサイトを含むことが分かった。
この活性アルミナＤを無機フィラーとして用いた以外は、実施例５−１と同様にして、非水系二次電池を得た。
［比較例５−７］
無機フィラーとして平均粒子径２μｍ、比表面積４００ｍ^２／ｇのゼオライト（ＨＳＺ−９８０ＨＯＡ；東ソー社製）を用いた以外は、実施例５−１と同様にして、非水系二次電池を得た。
［比較例５−８］
無機フィラーとして活性アルミナを使用せずに、平均粒子径２μｍ、比表面積３００ｍ^２／ｇのシリカ（東海化学工業所製；ＭＬ−３８４）を用いた以外は、実施例１と同様にして、非水系二次電池を得た。
［比較例５−９］
活性炭（関西熱化学社製；ＭＳＰ−２０）を、ジメチルアセトアミド（ＤＭＡｃ）を分散溶剤とした湿式粉砕（２ｍｍ径のジルコニアビーズミル）を行うことで、平均粒子径０．６μｍ、比表面積１６００ｍ^２／ｇの活性炭を得た。
この活性炭を無機フィラーとして用いた以外は実施例５−１と同様にして、非水系二次電池を得た。
［比較例５−１０］
実施例５−６で製造した正極を用いた以外は、比較例５−１と同様にして、非水系二次電池を得た。
［容量維持率の測定］
以上のようにして作製した実施例および比較例の非水系二次電池について、６０℃の恒温槽中において、充放電測定装置（北斗電工社製 ＨＪ−１０１ＳＭ６）を使用し、充放電特性を測定した。充放電条件について、充電は０．２Ｃで４．２Ｖまで８時間充電を行い、放電については０．２Ｃで２．７５Ｖまで放電を行い、容量維持率は初期放電容量に対する５００サイクル時点での放電容量の割合とした。測定結果を表９に示す。

［性能評価］
実施例５−１〜５−３及び比較例５−１〜５−３の結果から分かるように、活性アルミナをセパレータに含有する実施例はすべて７０パーセント以上の優れた容量維持率を示した。しかし、活性アルミナを含有しない比較例５−１〜５−３は容量維持率が５０％程度と低いものであった。さらに、実施例５−３〜５−５はセパレータに活性アルミナを含有する層を積層させた構成であるが、すべてにおいて容量維持率が７０％と優れていた。また、実施例５−４と５−５の比較からも、正極および負極の少なくともいずれか一方に活性アルミナを含有した層が存在すれば、有効であることが確認された。
実施例５−１〜５−２及び比較例５−４〜５−６の結果から分かるように、活性アルミナの比表面積が増加するにつれて容量維持率が優れていく傾向が観察された。そして、比較例５−６の比表面積２００ｍ^２／ｇでは効果が不十分であり、実施例５−２の比表面積が３５０ｍ^２／ｇの活性アルミナであれば効果が十分に確認できたことから、活性アルミナの比表面積は３００ｍ^２／ｇ以上であることが好ましいと言える。また、比較例５−７および５−８では、活性アルミナの代わりに比表面積が３００ｍ^２／ｇ以上のゼオライトとシリカを用いたが、容量維持率が６２％以下と活性アルミナ程は優れた効果を示さなかった。また、比表面積が１６００ｍ^２／ｇである活性炭を用いた比較例５−９は実施例５−１〜５−２と比較して容量維持率が６２％と低い値となった。このことより、比表面積は１０００ｍ^２／ｇ以下であることが好ましく、より好ましくは５００ｍ^２／ｇ以下であることが好適であると言える。一方、真密度では２．７ｇ／ｃｍ^３以下及び３．９ｇ／ｃｍ^３だと容量維持率が低く、２．８〜３．３ｇ／ｃｍ^３の範囲であればより良好な結果が得られることが分かった。以上のことを踏まえると、活性アルミナ特有の表面状態がＨＦの活性を低下させたために、容量維持率が向上したと推測できる。
正極活物質をマンガン酸リチウムにした実施例５−６と比較例５−１０でも、活性アルミナを含有させたセパレータを用いることで、容量維持率が７０％以上と優れた結果が得られた。また、比較例５−１０はマンガン酸リチウムを使用したため、コバルト酸リチウムよりＨＦによる正極からの金属の溶解が起こったため、容量維持率が４２％と低くなったと考えられる。
活性アルミナを電極に含有させた系と、電極表面に活性アルミナの層を積層させた系である実施例５−７〜５−１０を比較すると、すべての実施例において容量維持率７０％以上と優れている。これにより、活性アルミナの存在場所は、電極中に含有または電極表面に積層されても効果的であることが確認された。
以上の性能評価結果をまとめると、容量維持率が優れた非水系二次電池を得るためには、比表面積が３００〜１０００ｍ^２／ｇの活性アルミナを非水系二次電池に含有させること、また活性アルミナの存在場所は特に限定しなくてもよいことが知見として得られた。
［ＨＦの除去性能］
上述した実施例５−１，５−２及び比較例５−１の非水系二次電池について、上述した容量維持率の測定を行った後、電池を分解して非水電解質を抽出した。そして、この電解質中におけるＨＦの含有量を測定した。
具体的に、ＨＦ含有量の測定は、容量維持率を測定した後の非水系二次電池を分解した後、エチレンカーボネートとエチルメチルカーボネートを３：７の重量比で混合した所定量の溶液中に１週間放置することにより、電池内に存在するＨＦを溶液で抽出した。そして、ブロモチモールブルーを指示薬として、水酸化ナトリウム水溶液で滴定を行い、抽出した溶液中の酸濃度を求めた。最後に、求めた酸濃度を非水系二次電池に用いた電解液重量当たりに換算した値を、ＨＦ含有量（ｐｐｍ）とした。各サンプルについての測定結果を以下の表１０に示す。なお、電池を構成する前の電解質中のＨＦ含有量は３０ｐｐｍであった。

表１０の結果からも分かるように、実施例５−１，５−２の活性アルミナを使用した電池においては、比較例５−１と比較してＨＦの残存量が少ないことが分かる。これは、本発明における活性アルミナによって、ＨＦが好適に捕捉されていることによるものと考えられる。
（６）第六の形態に係る実施例
以下、本発明の第六の形態に係る実施例について説明する。なお、無機フィラーの平均粒子径、比表面積、真密度、結晶構造および元素比、ならびに膜厚の測定法については、上述した通りである。
［実施例６−１］
上述した実施例５−１と同様にして非水系二次電池を作製した。
［実施例６−２］
上述した実施例５−２と同様にして非水系二次電池を作製した。
［実施例６−３］
上述した実施例５−３と同様にして非水系二次電池を作製した。
［実施例６−４］
上述した実施例５−４と同様にして非水系二次電池を作製した。
［実施例６−５］
上述した実施例５−５と同様にして非水系二次電池を作製した。
［実施例６−６］
上述した実施例５−９と同様にして非水系二次電池を作製した。
［実施例６−７］
上述した実施例５−１０と同様にして非水系二次電池を作製した。
［比較例６−１］
上述した比較例５−１と同様にして非水系二次電池を作製した。
［比較例６−２］
上述した比較例５−２と同様にして非水系二次電池を作製した。
［比較例６−３］
上述した比較例５−３と同様にして非水系二次電池を作製した。
［比較例６−４］
無機フィラーとしてアルミナＡを使用せずに、平均粒子径０．５μｍ、比表面積７ｍ^２／ｇの非多孔質のアルミナＥ（昭和電工製； ＡＬ−１６０ＳＧ−３）を用いた以外は、実施例６−１と同様にして、非水系二次電池を得た。なお、このアルミナＥについてＸＲＤ解析を行ったところ、α−アルミナに由来する明確なピークが観察された。
［比較例６−５］
無機フィラーとしてアルミナＡを使用せずに、平均粒子径０．６μｍ、比表面積１５ｍ^２／ｇの非多孔質のアルミナＦ（大明化学工業製； Ｃ０６）を用いた以外は、実施例６−１と同様にして、非水系二次電池を得た。なお、このアルミナＦについてＸＲＤ解析を行ったところ、ベーマイトに由来する明確なピークが観察された。
［比較例６−６］
フィラーとしてアルミナＡを使用せずに、平均粒子径０．８μｍ、比表面積７ｍ^２／ｇの非多孔質の水酸化アルミニウム（昭和電工製； Ｈ−４３Ｍ）を用いた以外は、実施例６−１と同様にして、非水系二次電池を得た。なお、この水酸化アルミニウムについてＸＲＤ解析を行ったところ、ギブサイトに由来する明確なピークが観察された。
［比較例６−７］
上述した比較例５−７と同様にして非水系二次電池を作製した。
［比較例６−８］
無機フィラーとしてアルミナＡを使用せずに、平均粒子径２μｍ、比表面積６００ｍ^２／ｇのシリカ（東海化学工業所製；ＭＬ−６４４）を用いた点以外は、実施例６−１と同様にして、非水系二次電池を得た。
［比較例６−９］
上述した比較例５−９と同様にして非水系二次電池を作製した。
［容量維持率の測定］
以上のようにして作製した実施例および比較例の非水系二次電池について、６０℃の恒温槽中において、充放電測定装置（北斗電工社製 ＨＪ−１０１ＳＭ６）を使用し、充放電特性を測定した。充放電条件について、充電は０．２Ｃで４．２Ｖまで８時間充電を行い、放電については０．２Ｃで２．７５Ｖまで放電を行い、容量維持率は初期放電容量に対する４００サイクル時点での放電容量の割合とした。測定結果を表１１に示す。
［１４０℃のオーブン試験］
以上のようにして作製した実施例および比較例の非水系二次電池について、０．２Ｃで４．２Ｖまで８時間充電を行った後、１４０℃の防暴乾燥機の中に２４時間保管した。その結果、発火が確認された場合は×と評価し、発火が確認されなかった場合は○と評価した。結果を表１１に示す。

［性能評価］
表１１において、実施例６−１〜６−２及び比較例６−１〜６−６の結果より、アモルファス状のアルミナをセパレータに含有する構成であれば、７０％以上の優れた容量維持率を示すことが分かる。フィラーを含有しない比較例６−１〜６−３は容量維持率が６０％以下と低いものであった。さらに、１４０℃オーブン試験より、実施例６−１〜６−２では発火が確認されなかったが、比較例６−１では発火が確認されたので、実施例６−１〜６−２は内部短絡における安全性にも優れていることが分かった。
また、アルミナの構造の比較では、アモルファス以外の構造を有する比較例６−４〜６−６は容量維持率が６０％以下と低く、さらに１４０℃オーブン試験において、発火が確認された。このことから、アモルファス状のアルミナはサイクル特性と内部短絡における安全性の両方に優れることが分かった。
また、他の無機フィラーとしてゼオライト、シリカ、活性炭を比較例６−７〜６−９において評価したが、実施例６−１〜６−２と比較して容量維持率が６０％強とわずかに低く、１４０℃オーブン試験においては発火が確認された。このことからも、添加する無機フィラーはアモルファス状のアルミナが優れていることが分かる。
アルミナの存在場所として、実施例６−１〜６−８を比較すると、すべてにおいて容量維持率が７０％以上と優れ、オーブン試験においても発火しなかったことより、アモルファスアルミナの存在場所は、正極と負極の間のいずれかの部位に存在すれば、サイクル特性と内部短絡による安全性に優れることが分かった。
［熱収縮率の測定］
１４０℃オーブン試験における発火の有無の原因を調査するために、実施例６−１〜６−２、および比較例６−１，６−４〜６−９のセパレータについて、熱収縮率を測定した。
具体的には、まずサンプルとなるセパレータを１８ｃｍ（ＭＤ方向）×６ｃｍ（ＴＤ）方向に切り出した。ＴＤ方向を２等分する線上に上部から２ｃｍ、１７ｃｍの箇所（点Ａ、点Ｂ）に印を付けた。また、ＭＤ方向を２等分する線上に左から１ｃｍ、５ｃｍの箇所に印を付けた。これにクリップをつけ１０５℃に調整したオーブンの中につるし、無張力下で３０分間熱処理した。２点ＡＢ間、ＣＤ間長さを熱処理前後で測定し、以下の２式から熱収縮率を求めた。各サンプルについての測定結果を表１２にまとめて示す。
ＭＤ方向熱収縮率＝（熱処理前のＡＢ間長さ−熱処理後のＡＢ間長さ）／（熱処理前のＡＢ間長さ）×１００
ＴＤ方向熱収縮率＝（熱処理前のＣＤ間長さ−熱処理後のＣＤ間長さ）／（熱処理前のＣＤ間長さ）×１００

表１２より、１４０℃オーブン試験にて発火しなかった実施例６−１〜６−２は、熱収縮率がＭＤ方向において１５％以下、ＴＤ方向については２％と低かった。これに対して、フィラーを含有していない比較例６−１、アモルファス以外のアルミナあるいは水酸化アルミニウムである比較例６−４〜６−６、そしてアルミナ以外のフィラーである比較例６−７〜６−９は、ＭＤ方向の熱収縮率が２０％以上、ＴＤ方向の熱収縮率は３％以上と実施例６−１〜６−２と比較して高かった。このことから、熱収縮率がＭＤ方向で２０％以上、ＴＤ方向が３％以上であると、１４０℃オーブン試験において非水系二次電池内のセパレータが破膜し、内部短絡による発火を引き起こすと推測できる。
以上の性能評価結果をまとめると、容量維持率が優れ、かつ１４０℃オーブン試験において発火しない安全性に優れた非水系二次電池を得るためには、アモルファス状のアルミナを負極と正極間に含有させることが良いという知見を得ることができた。(1) Examples according to the first and second embodiments
Examples according to the first and second aspects of the present invention will be described below. The measurement method applied in this example is as follows.
[Average particle size of inorganic filler]
It measured with the laser diffraction type particle size distribution measuring apparatus (Shimadzu Corporation make; SALD-2000J). Water was used as a dispersion medium, and a small amount of nonionic surfactant “Triton X-100” was used as a dispersant. The center particle diameter (D50) in the obtained volume particle size distribution was defined as the average particle diameter.
[Specific surface area of inorganic filler]
Measurement was performed according to JIS K 8830. Using NOVA-1200 (manufactured by Yuasa Ionics Co., Ltd.), the BET equation was used for analysis and determination by the nitrogen gas adsorption method. The sample weight at the time of measurement was 0.1 to 0.2 g. The analysis was performed by a three-point method, and the specific surface area was obtained from the BET plot.
[Analysis of crystal structure of inorganic filler]
As for the crystal structure of the inorganic filler, the XRD diffraction spectrum of the inorganic filler was measured with a powder X-ray diffractometer, and the crystal structure in the bulk structure was analyzed from this spectrum. For the X-ray diffractometer, an X-ray generator ultrax 18 manufactured by Rigaku was used, and Cu-Kα rays were used. The measurement conditions were 45 KV-60 mA, sampling interval 0.020 °, measurement range (2θ) 5 ° to 90 °, and scan speed 5 ° / min. As the measurement sample, an agate mortar was used to pulverize the inorganic filler manually and packed into a glass sample plate. The glass sample plate has a groove having a length of 18 mm, a width of 20 mm, and a depth of 0.2 mm, and the thickness of the sample is the depth of the glass sample plate.
[Measurement of element ratio of inorganic filler]
The element ratio of 0 / Al existing on the surface of the inorganic filler was measured using an X-ray photoelectron spectrometer (manufactured by VG, ESCALAB 200), and calculated from the obtained 01s and Al2p intensity ratio. MgKα ray was used as the X-ray source.
[Film thickness]
It was determined by measuring 20 points with a contact-type film thickness meter (manufactured by Mitutoyo Co., Ltd.) and averaging them. Here, the contact terminal used was a cylindrical one having a bottom surface of 0.5 cm in diameter.
[Example 1-1]
Aluminum hydroxide (manufactured by Showa Denko; H-43M) was heat-treated at 280 ° C., average particle diameter 0.8 μm, specific surface area 400 m ² / G of activated alumina was obtained. When an XRD analysis was performed on this activated alumina, a peak derived from boehmite was observed in a broad chart, and the integrated intensity of the peak at 2θ = 14.39 ° was 98 cps · deg. The integrated intensity of was 0.07 with respect to the integrated intensity of a broad peak existing over 2θ = 10 to 60 deg. Therefore, this activated alumina can be said to be amorphous alumina because it mainly has an amorphous bulk structure and a very small amount of boehmite phase is mixed. The 0 / Al element ratio on the surface of the activated alumina was 1.54.
Conex (registered trademark; manufactured by Teijin Techno Products), which is polymetaphenylene isophthalamide, was used as the meta-type wholly aromatic polyamide. A Conex solution was prepared by dissolving so that Conex was 7% by weight in a weight ratio of dimethylacetamide (DMAc): tripropylene glycol (TPG) = 60: 40.
The activated alumina was dispersed in the Conex solution so that the activated alumina: Conex = 30: 70 (weight ratio) to prepare a slurry.
The slurry was applied to a glass plate, and this was immersed in a coagulating liquid having a weight ratio of water: DMAc: TPG = 70: 18: 12 (weight ratio) of 30 ° C., then washed with water and dried. It was. And the porous film formed on the glass plate was peeled, and the 10-micrometer-thick porous film with sufficient handling property was obtained.
[Example 1-2]
Activated alumina with an average particle diameter of 4 μm and a specific surface area of 700 m ² A porous membrane having a film thickness of 10 μm having sufficient handling properties was obtained in the same manner as in Example 1-1 except that the zeolite was changed to / g zeolite (HSZ-341NHA; manufactured by Tosoh Corporation).
[Example 1-3]
By performing wet pulverization (2-mm zirconia bead mill) using dimethylacetamide (DMAc) as a dispersion solvent on activated carbon (manufactured by Kansai Thermal Chemical Co., Ltd .; MSP-20), an average particle size of 0.6 μm and a specific surface area of 1600 m ² / G of activated carbon was obtained.
A porous film having a thickness of 10 μm was obtained in the same manner as in Example 1-1 except that the activated alumina was changed to the activated carbon. In addition, this porous film was a little weak compared with the thing of Example 1-1, and was inferior to handleability.
[Example 1-4]
A porous film having a film thickness of 10 μm was obtained in the same manner as in Example 1-1 except that the weight ratio of activated alumina to conex was changed to activated alumina: conex = 70: 30 (weight ratio). This porous film was slightly brittle and inferior in handleability as compared with that of Example 1-1.
[Example 1-5]
The porous membrane for batteries produced in Example 1-1 was coated with a polyethylene aqueous dispersion (Kemipearl W900: manufactured by Mitsui Chemicals) and dried to obtain a porous membrane having a thickness of 13 μm.
[Comparative Example 1-1]
Activated alumina with an average particle size of 0.8 μm and a specific surface area of 8 m ² A porous film with a handleability of 10 μm in thickness was obtained in the same manner as in Example 1-1, except that / g aluminum hydroxide (made by Showa Denko; H-43M) was used.
[Comparative Example 1-2]
Activated alumina with an average particle diameter of 0.6 μm and a specific surface area of 6 m ² A porous film having a film thickness of 10 μm and a sufficient handling property was obtained in the same manner as in Example 1-1, except that it was changed to / g alumina (manufactured by Showa Denko: AL160SG-3).
[Comparative Example 1-3]
Conex (registered trademark; manufactured by Teijin Techno Products), which is polymetaphenylene isophthalamide, was used as the meta-type wholly aromatic polyamide. A Conex solution was prepared by dissolving so that Conex was 7% by weight in a weight ratio of dimethylacetamide (DMAc): tripropylene glycol (TPG) = 60: 40.
The Conex solution was applied to a glass plate, and this was immersed in a coagulating liquid having a weight ratio of water: DMAc: TPG = 70: 18: 12 (weight ratio) of 30 ° C., then washed with water and dried. Went. And the porous film formed on the glass plate was peeled, and the 10-micrometer-thick porous film with sufficient handling property was obtained.
[Comparative Example 1-4]
As polyethylene powder, GUR2126 (weight average molecular weight 41.50 million, melting point 141 ° C.) and GRX143 (weight average molecular weight 560,000, melting point 135 ° C.) manufactured by Ticona were used. The liquid paraffin (manufactured by Matsumura Oil Research Co., Ltd .; Smoyl P-350P; boiling point 480 ° C.) and decalin so that GUR2126 and GURX143 are 1: 9 (weight ratio) and the polyethylene concentration is 15% by weight. A polyethylene solution was prepared by dissolving in a mixed solvent. The composition of the polyethylene solution is polyethylene: liquid paraffin: decalin = 30: 45: 25 (weight ratio).
A slurry in which zeolite (HSZ-500KOA; manufactured by Tosoh Corporation) was dispersed in the polyethylene solution was prepared. Here, the mixing ratio of polyethylene and zeolite was 50:50 by weight. Zeolite has an average particle size of 3 μm and a specific surface area of 290 m. ² / G.
This slurry was extruded from a die at 148 ° C. and cooled in a water bath to prepare a gel tape (base tape). The base tape was dried at 60 ° C. for 8 minutes and at 95 ° C. for 15 minutes, and the base tape was biaxially stretched by successively performing longitudinal stretching and transverse stretching. Here, the longitudinal stretching was performed at a stretching ratio of 5.5 times and a stretching temperature of 90 ° C., the transverse stretching was performed at a stretching ratio of 11.0 times, and the stretching temperature was 105 ° C. After stretching, heat setting was performed at 125 ° C. Next, this was immersed in a methylene chloride bath to extract liquid paraffin and decalin. Thereafter, the film was dried at 50 ° C. and annealed at 120 ° C. to obtain a porous film with sufficient handling property of 10 μm.
[Comparative Example 1-5]
Aluminum hydroxide (manufactured by Showa Denko; H-43M) was heat-treated at 205 ° C., average particle size 0.8 μm, specific surface area 30 m ² / G of activated alumina was obtained. As a result of structural analysis of this activated alumina by XRD, a broad peak derived from the amorphous structure was not confirmed, and a peak derived from the gibbsite was clearly observed, so that the bulk structure was mainly gibbsite and amorphous. It turned out not to be alumina.
A porous membrane having a film thickness of 10 μm and sufficient handleability was obtained by the same method as in Example 1-1, except that this activated alumina was used in place of the activated alumina of Example 1-1.
[Bearing test]
For each of the porous membranes of Examples 1-1 to 1-5 and Comparative Examples 1-1 to 1-5 produced as described above, a membrane breaking test was performed as follows. First, the porous film of the sample was fixed to a metal frame having a length of 6.5 cm and a width of 4.5 cm. The temperature of the oven was set to 175 ° C., and the sample fixed to the metal frame was put in the oven and held for 1 hour. At this time, a film that was not broken and the shape could be maintained was evaluated as ◯, and a film that was not evaluated as X. The results are shown in Table 1.
[Gas generation test]
For each of the porous membranes of Examples 1-1 to 1-5 and Comparative Examples 1-1 to 1-5 produced as described above, a membrane breaking test was performed as follows. First, each porous membrane to be a sample is 240 cm ² And was vacuum-dried at 85 ° C. for 16 hours. This was put in an aluminum pack in an environment with a dew point of −60 ° C. or less, an electrolyte was further injected, the aluminum pack was sealed with a vacuum sealer, and a measurement cell was produced. Here, the electrolyte is 1M LiPF ₆ Ethylene carbonate (EC) / ethyl methyl carbonate (EMC) = 3/7 (weight ratio) (manufactured by Kishida Chemical Co., Ltd.). The measurement cell was stored at 85 ° C. for 3 days, and the volume of the measurement cell before and after storage was measured. A value obtained by subtracting the volume of the measurement cell before storage from the volume of the measurement cell after storage was taken as the gas generation amount. Here, the volume measurement of the measurement cell was performed at 23 ° C., and was performed using an electronic hydrometer (manufactured by Alpha Mirage Co., Ltd .; EW-300SG) according to Archimedes' principle. The results are shown in Table 1.

[Production of non-aqueous secondary battery]
Using each of the porous membranes of Examples 1-1 to 1-5 and Comparative Examples 1-1 to 1-5 produced as described above, non-aqueous secondary batteries were produced as follows.
Lithium cobalt oxide (LiCoO ₂ NIPPON CHEMICAL INDUSTRIES CO., LTD.) 89.5 parts by weight of powder, acetylene black (manufactured by Denki Kagaku Kogyo; trade name Denka Black) 4.5 parts by weight, polyvinylidene fluoride (manufactured by Kureha Chemical Co., Ltd.) 6 parts by weight These were kneaded using an N-methyl-2pyrrolidone solvent to prepare a slurry. The obtained slurry was applied onto an aluminum foil having a thickness of 20 μm, dried and pressed to obtain a positive electrode having a thickness of 100 μm.
87 parts by weight of mesophase carbon microbeads (MCMB: Osaka Gas Chemical Co., Ltd.) powder, 3 parts by weight of acetylene black (manufactured by Denki Kagaku Kogyo; trade name Denka Black), 10 parts by weight of polyvinylidene fluoride (manufactured by Kureha Chemical Co., Ltd.) Thus, these were knead | mixed using the N-methyl-2 pyrrolidone solvent, and the slurry was produced. The obtained slurry was applied onto a copper foil having a thickness of 18 μm, dried and pressed to obtain a negative electrode having a thickness of 90 μm.
The positive electrode and the negative electrode were opposed to each other through a separator. This was impregnated with an electrolytic solution and sealed in an exterior made of an aluminum laminate film to produce a non-aqueous secondary battery. Here, the electrolyte is 1M LiPF ₆ Ethylene carbonate / ethyl methyl carbonate (3/7 weight ratio) (manufactured by Kishida Chemical Co., Ltd.) was used.
Here, as the separator, each porous membrane of Examples 1-1 to 1-5 and Comparative Examples 1-1 to 1-5 was used, and Examples 1-6 to 1-10 and Comparative Example 1 shown in Table 2, respectively. Non-aqueous secondary batteries of −6 to 1-10 were produced. The porous membranes of Examples 1-3 and 1-4 were used by being laminated with a polyethylene microporous membrane (PE microporous membrane). The PE microporous film used here was produced by the following method.
First, as the polyethylene powder, GUR2126 (weight average molecular weight 4150,000, melting point 141 ° C.) and GURX143 (weight average molecular weight 560,000, melting point 135 ° C.) manufactured by Ticona were used. Liquid paraffin (manufactured by Matsumura Oil Research Co., Ltd .; Smoyl P-350P; boiling point 480 ° C.) and decalin so that GUR2126 and GURX143 are 1: 9 (weight ratio) and the polyethylene concentration is 30% by weight. A polyethylene solution was prepared by dissolving in a mixed solvent. The composition of the polyethylene solution is polyethylene: liquid paraffin: decalin = 30: 45: 25 (weight ratio).
This polyethylene solution was extruded from a die at 148 ° C. and cooled in a water bath to prepare a gel tape (base tape). The base tape was dried at 60 ° C. for 8 minutes and at 95 ° C. for 15 minutes, and the base tape was biaxially stretched by successively performing longitudinal stretching and transverse stretching. Here, the longitudinal stretching was performed at a stretching ratio of 5.5 times and a stretching temperature of 90 ° C., the transverse stretching was performed at a stretching ratio of 11.0 times, and the stretching temperature was 105 ° C. After stretching, heat setting was performed at 125 ° C. Next, this was immersed in a methylene chloride bath to extract liquid paraffin and decalin. Then, it dried at 50 degreeC and annealed at 120 degreeC, and obtained the polyethylene microporous film | membrane with a film thickness of 9 micrometers.
[Oven test]
Each battery produced as described above was charged with constant voltage / constant current charging of 0.2 C and 4.2 V for 8 hours. And 1.8kg / cm ² The sample was put in an oven with the above load applied, heated from 30 ° C. to 150 ° C. at a heating rate of 5 ° C./min, and then held at 150 ° C. for 1 hour. At this time, the smoked product was evaluated as x, and the smoked product was evaluated as o. The results are shown in Table 2.
[Cycle characteristics]
The cycle characteristics of each battery produced as described above were evaluated. Evaluation of cycle characteristics is 1C 4.2V 2 hours constant current / constant voltage charge, 1C, charge / discharge with constant current discharge of 2.75V cutoff, 300 cycles when the first cycle capacity is used as a reference The eye capacity retention rate was used as an index of cycle characteristics. The temperature at the time of measurement was 30 ° C. The results are shown in Table 2.
[Save test]
The battery produced as described above was charged for 8 hours at a constant voltage / constant current charge of 0.2 C, 4.2 V. And 1.8kg / cm ² The sample was put in an oven with a load of and stored at 85 ° C. for 3 days. After storage, a constant current discharge of 0.2 C and 2.75 V cut-off was performed to determine the remaining capacity. The capacity retention rate was calculated by multiplying the value obtained by dividing the remaining capacity by the initial capacity by 100. This capacity maintenance rate was used as an index for evaluating the storage test. The results are shown in Table 2.
[Battery swelling]
Each battery after the above storage test was visually confirmed. If the battery was clearly swollen, it was judged as x, and if the battery was not clearly swollen in appearance, it was judged as good. In this case, the swelling of the battery is due to the generation of gas in the battery. The results are shown in Table 2.

[Example 1-11]
Lithium cobalt oxide (LiCoO ₂ NIPPON CHEMICAL INDUSTRIES CO., LTD.) 89.5 parts by weight of powder, acetylene black (manufactured by Denki Kagaku Kogyo; trade name Denka Black) 4.5 parts by weight, and polyvinylidene fluoride (manufactured by Kureha Chemical Co., Ltd.) 6 parts by weight. These were kneaded using an N-methyl-2pyrrolidone solvent to prepare a slurry. The obtained slurry was applied onto an aluminum foil having a thickness of 20 μm, dried and pressed to obtain a positive electrode having a thickness of 100 μm.
The slurry prepared in Example 1-4 was applied to the surface of the positive electrode, and this was mixed in a coagulating liquid having a weight ratio of water: DMAc: TPG = 70: 18: 12 (weight ratio) of 30 ° C. Immersion was followed by washing with water and drying to form a porous membrane for a battery of the present invention having a thickness of 3 μm on the surface of the positive electrode.
87 parts by weight of mesophase carbon microbeads (MCMB: Osaka Gas Chemical Co., Ltd.) powder, 3 parts by weight of acetylene black (manufactured by Denki Kagaku Kogyo; trade name Denka Black), 10 parts by weight of polyvinylidene fluoride (manufactured by Kureha Chemical Co., Ltd.) Thus, these were knead | mixed using the N-methyl-2 pyrrolidone solvent, and the slurry was produced. The obtained slurry was applied onto a copper foil having a thickness of 18 μm, dried and pressed to obtain a negative electrode having a thickness of 90 μm.
The positive electrode and the negative electrode were opposed to each other through a separator. This was impregnated with an electrolytic solution and sealed in an exterior made of an aluminum laminate film to produce a non-aqueous secondary battery. Here, the electrolyte is 1M LiPF ₆ Ethylene carbonate / ethyl methyl carbonate (3/7 weight ratio) (manufactured by Kishida Chemical Co., Ltd.) was used. The separator used was the PE microporous membrane in Examples 1-8 and 1-9 described above.
The battery of Example 1-11 was also evaluated for the oven test, cycle characteristics, storage test, and battery blistering described above. The results are shown in Table 3.
[Example 1-12]
Lithium cobalt oxide (LiCoO ₂ NIPPON CHEMICAL INDUSTRIES CO., LTD.) 89.5 parts by weight of powder, acetylene black (manufactured by Denki Kagaku Kogyo; trade name Denka Black) 4.5 parts by weight, and polyvinylidene fluoride (manufactured by Kureha Chemical Co., Ltd.) 6 parts by weight. These were kneaded using an N-methyl-2pyrrolidone solvent to prepare a slurry. The obtained slurry was applied onto an aluminum foil having a thickness of 20 μm, dried and pressed to obtain a positive electrode having a thickness of 100 μm.
87 parts by weight of mesophase carbon microbeads (MCMB: Osaka Gas Chemical Co., Ltd.) powder, 3 parts by weight of acetylene black (manufactured by Denki Kagaku Kogyo; trade name Denka Black), 10 parts by weight of polyvinylidene fluoride (manufactured by Kureha Chemical Co., Ltd.) Thus, these were knead | mixed using the N-methyl-2 pyrrolidone solvent, and the slurry was produced. The obtained slurry was applied onto a copper foil having a thickness of 18 μm, dried and pressed to obtain a negative electrode having a thickness of 90 μm.
The slurry prepared in Example 1-4 was applied to the surface of the negative electrode, and this was put into a coagulating liquid having a weight ratio of water: DMAc: TPG = 70: 18: 12 (weight ratio) of 30 ° C. Immersion was followed by washing with water and drying to form a porous membrane for a battery of the present invention having a thickness of 3 μm on the negative electrode surface.
The positive electrode and the negative electrode were opposed to each other through a separator. This was impregnated with an electrolytic solution and sealed in an exterior made of an aluminum laminate film to produce a non-aqueous secondary battery. Here, the electrolyte is 1M LiPF ₆ Ethylene carbonate / ethyl methyl carbonate (3/7 weight ratio) (manufactured by Kishida Chemical Co., Ltd.) was used. The separator used was the PE microporous membrane in Examples 1-8 and 1-9 described above.
The battery of Example 1-12 was also evaluated for the above-described oven test cycle characteristics, storage test, and battery blistering. The results are shown in Table 3.
[Example 1-13]
Lithium cobalt oxide (LiCoO ₂ NIPPON CHEMICAL INDUSTRIES CO., LTD.) 89.5 parts by weight of powder, acetylene black (manufactured by Denki Kagaku Kogyo; trade name Denka Black) 4.5 parts by weight, and polyvinylidene fluoride (manufactured by Kureha Chemical Co., Ltd.) 6 parts by weight. These were kneaded using an N-methyl-2pyrrolidone solvent to prepare a slurry. The obtained slurry was applied onto an aluminum foil having a thickness of 20 μm, dried and pressed to obtain a positive electrode having a thickness of 100 μm.
87 parts by weight of mesophase carbon microbeads (MCMB: Osaka Gas Chemical Co., Ltd.) powder, 3 parts by weight of acetylene black (manufactured by Denki Kagaku Kogyo; trade name Denka Black), 10 parts by weight of polyvinylidene fluoride (manufactured by Kureha Chemical Co., Ltd.) Thus, these were knead | mixed using the N-methyl-2 pyrrolidone solvent, and the slurry was produced. The obtained slurry was applied onto a copper foil having a thickness of 18 μm, dried and pressed to obtain a negative electrode having a thickness of 90 μm.
The slurry prepared in Example 1-4 was applied to the surfaces of the positive electrode and the negative electrode, and this was coagulated liquid having a weight ratio of water: DMAc: TPG = 70: 18: 12 (weight ratio) of 30 ° C. It was immersed in, then washed with water and dried to form a porous membrane for a battery of the present invention having a thickness of 3 μm on the positive and negative electrode surfaces.
The positive electrode and the negative electrode were opposed to each other through a separator. This was impregnated with an electrolytic solution and sealed in an exterior made of an aluminum laminate film to produce a non-aqueous secondary battery. Here, the electrolyte is 1M LiPF ₆ Ethylene carbonate / ethyl methyl carbonate (3/7 weight ratio) (manufactured by Kishida Chemical Co., Ltd.) was used. The separator used was the PE microporous membrane in Examples 1-8 and 1-9 described above.
The battery of Example 1-13 was also evaluated for the oven test, cycle characteristics, storage test, and battery blistering described above. The results are shown in Table 3.

(2) Examples according to the third and fourth aspects
Examples according to the third and fourth aspects of the present invention will be described below. The measurement method applied in this example is as follows. In addition, about the average particle diameter of an inorganic filler, a specific surface area, a crystal structure and element ratio, and the measuring method of a film thickness, it is the same as that of the case which concerns on the 1st and 2nd aspect mentioned above. The separator film breakage test and gas generation amount test are also the same as those in the first and second embodiments.
[Porosity]
About the film | membrane used as a sample, the weight (Wi: g / m) of each constituent material ² ) True density (di: g / cm ³ ) To obtain the sum (Σ (Wi / di)). The porosity (%) was calculated by dividing this by the film thickness (μm) and multiplying the value subtracted from 1 by 100.
[Gurley value]
It measured according to JIS P8117.
[Puncture strength]
Using a KES-G5 handy compression tester manufactured by Kato Tech Co., Ltd., a piercing test was performed under the conditions of a radius of curvature of the needle tip of 0.5 mm and a piercing speed of 2 mm / second, and the maximum piercing load was defined as the piercing strength. Here, the sample was sandwiched and fixed in a metal frame (sample holder) having a hole of Φ11.3 mm.
[Shutdown characteristics (SD characteristics)]
First, a separator as a sample is punched out to a diameter of 19 mm, dipped in a 3 wt% methanol solution of a nonionic surfactant (manufactured by Kao Corporation; Emulgen 210P), and air-dried. Then, the separator was impregnated with the electrolytic solution and sandwiched between SUS plates (Φ15.5 mm). Here, the electrolyte is 1M LiBF ₄ Propylene carbonate / ethylene carbonate (1/1 weight ratio) was used. This was enclosed in a 2032 type coin cell. I took the lead from the coin cell, put a thermocouple, and put it in the oven. The cell resistance was measured by raising the temperature at a rate of temperature increase of 1.6 ° C./min and simultaneously applying alternating current with an amplitude of 10 mV and a frequency of 1 kHz.
The resistance value is 10 in the range of 135 to 150 ° C. in the above measurement. ³ ohm-cm ² In the case of the above, the SD characteristic was evaluated as ◯, and in the case where it was not, the SD characteristic was evaluated as x.
[Battery storage characteristics]
Using the separators produced in the following examples and comparative examples, non-aqueous secondary batteries were produced as follows.
Lithium cobalt oxide (LiCoO ₂ NIPPON CHEMICAL INDUSTRIES CO., LTD.) 89.5 parts by weight of powder, acetylene black (manufactured by Denki Kagaku Kogyo; trade name Denka Black) 4.5 parts by weight, polyvinylidene fluoride (manufactured by Kureha Chemical Co., Ltd.) 6 parts by weight These were kneaded using an N-methyl-2pyrrolidone solvent to prepare a slurry. The obtained slurry was applied onto an aluminum foil having a thickness of 20 μm, dried and pressed to obtain a positive electrode having a thickness of 100 μm.
87 parts by weight of mesophase carbon microbeads (MCMB: Osaka Gas Chemical Co., Ltd.) powder, 3 parts by weight of acetylene black (manufactured by Denki Kagaku Kogyo; trade name Denka Black), 10 parts by weight of polyvinylidene fluoride (manufactured by Kureha Chemical Co., Ltd.) Thus, these were knead | mixed using the N-methyl-2 pyrrolidone solvent, and the slurry was produced. The obtained slurry was applied onto a copper foil having a thickness of 18 μm, dried and pressed to obtain a negative electrode having a thickness of 90 μm.
The positive electrode and the negative electrode were opposed to each other through the separators prepared in the following examples and comparative examples. This was impregnated with an electrolytic solution and sealed in an exterior made of an aluminum laminate film to produce a non-aqueous secondary battery. Here, the electrolyte is 1M LiPF ₆ Ethylene carbonate / ethyl methyl carbonate (3/7 weight ratio) (manufactured by Kishida Chemical Co., Ltd.) was used.
The non-aqueous secondary battery was subjected to constant current / constant voltage charging at 0.2 C 4.2 V for 8 hours and constant current discharge at 0.2 C, 2.75 V cutoff. The discharge capacity obtained at the fifth cycle was defined as the initial capacity of this cell. Then, constant current / constant voltage charging of 0.2C 4.2V for 8 hours was performed, and stored at 85 ° C. for 3 days. And the constant current discharge of 0.2C and 2.75V cut-off was performed, and the residual capacity in storage at 85 ° C. for 3 days was determined. A value obtained by dividing the remaining capacity by the initial capacity and multiplying by 100 was defined as a capacity retention rate, and this capacity retention rate was used as an index of storage characteristics of the battery.
[Battery swelling]
Each battery after the storage characteristics test of the above battery was visually confirmed, and it was judged that the battery was clearly swollen as x, and the battery that was not clearly swollen was judged as ○. . In this case, the swelling of the battery is due to the generation of gas in the battery.
[Example 2-1]
As polyethylene powder, GUR2126 (weight average molecular weight 41.50 million, melting point 141 ° C.) and GRX143 (weight average molecular weight 560,000, melting point 135 ° C.) manufactured by Ticona were used. Liquid paraffin (manufactured by Matsumura Oil Research Co., Ltd .; Smoyl P-350P; boiling point 480 ° C.) and decalin so that GUR2126 and GURX143 are 1: 9 (weight ratio) and the polyethylene concentration is 30% by weight. A polyethylene solution was prepared by dissolving in a mixed solvent. The composition of the polyethylene solution is polyethylene: liquid paraffin: decalin = 30: 45: 25 (weight ratio).
This polyethylene solution was extruded from a die at 148 ° C. and cooled in a water bath to prepare a gel tape (base tape). The base tape was dried at 60 ° C. for 8 minutes and at 95 ° C. for 15 minutes, and the base tape was biaxially stretched by successively performing longitudinal stretching and transverse stretching. Here, the longitudinal stretching was performed at a stretching ratio of 5.5 times and a stretching temperature of 90 ° C., the transverse stretching was performed at a stretching ratio of 11.0 times, and the stretching temperature was 105 ° C. After stretching, heat setting was performed at 125 ° C. Next, this was immersed in a methylene chloride bath to extract liquid paraffin and decalin. Then, it dried at 50 degreeC and obtained the polyethylene microporous film by annealing at 120 degreeC.
The obtained polyethylene microporous membrane has a basis weight of 4.7 g / m. ² The film thickness was 9 μm, the porosity was 45%, the Gurley value was 150 seconds / 100 cc, and the puncture strength was 300 g.
Conex (registered trademark; manufactured by Teijin Techno Products), which is polymetaphenylene isophthalamide, was used as the meta-type wholly aromatic polyamide. Conex solution was prepared by dissolving in 6% by weight of Conex in dimethylacetamide (DMAc): tripropylene glycol (TPG) = 60: 40 (weight ratio).
As a porous filler, an average particle diameter of 3 μm and a specific surface area of 290 m ² / G of zeolite (HSZ-500KOA; manufactured by Tosoh Corporation) was used. The zeolite was dispersed in the Conex solution so that the ratio of zeolite: Conex = 50: 50 (weight ratio) was obtained to prepare a dispersion.
Two Meyer bars were placed opposite to each other, and an appropriate amount of the dispersion was put between them. The polyethylene microporous membrane was passed between Mayer bars carrying the dispersion, and the dispersion was applied to both sides of the polyethylene microporous membrane. Here, the clearance between the Mayer bars was 30 μm, and the number of the Mayer bars was 2 and # 6. This was immersed in a coagulating liquid having a weight ratio of water: DMAc: TPG = 70: 18: 12 (weight ratio) of 30 ° C., then washed with water and dried. A heat-resistant porous layer made of Conex was formed to obtain a separator for a non-aqueous secondary battery of the present invention. The characteristics of the obtained non-aqueous secondary battery separator are shown in Tables 4 and 5. The characteristics of the separators according to the following examples and comparative examples are also shown in Tables 4 and 5.
[Example 2-2]
As a porous filler, the average particle diameter is 2 μm and the specific surface area is 400 m. ² / G of zeolite (HSZ-980HOA; manufactured by Tosoh Corporation) was used in the same manner as Example 2-1 to obtain a non-aqueous secondary battery separator.
[Example 2-3]
Porous filler has an average particle size of 4 μm and a specific surface area of 700 m ² / G of zeolite (HSZ-341NHA; manufactured by Tosoh Corporation) was used in the same manner as in Example 2-1, to obtain a nonaqueous secondary battery separator.
[Example 2-4]
Activated carbon (manufactured by Kansai Thermal Chemical Co., Ltd .; MSP-20) is subjected to wet pulverization (2 mm zirconia bead mill) using dimethylacetamide (DMAc) as a dispersion solvent, whereby an average particle diameter of 0.6 μm and a specific surface area of 1600 m ² / G of activated carbon was obtained. The separator for non-aqueous secondary batteries of this invention was obtained like Example 2-1, except the point which used this activated carbon as a porous filler.
[Example 2-5]
Porous filler has an average particle size of 1.4 μm and a specific surface area of 190 m ² A separator for a non-aqueous secondary battery of the present invention was obtained in the same manner as in Example 2-1, except that / g of activated alumina (manufactured by Sumitomo Chemical Co., Ltd .; KC-501) was used.
[Example 2-6]
Aluminum hydroxide (made by Showa Denko; H-43M) was heat-treated at 220 ° C., average particle size 0.8 μm, specific surface area 60 m ² / G of activated alumina was obtained. In addition, when the crystal structure of this activated alumina was analyzed by XRD, a broad peak derived from the amorphous structure was not confirmed, and a peak derived from the gibbsite was clearly observed. Therefore, the bulk structure was mainly gibbsite, It turned out not to be alumina.
The separator for non-aqueous secondary batteries of this invention was obtained like Example 2-1, except the point which used this activated alumina as a porous filler.
[Example 2-7]
Aluminum hydroxide (manufactured by Showa Denko; H-43M) was heat-treated at 280 ° C., average particle diameter 0.8 μm, specific surface area 400 m ² / G of activated alumina was obtained. When an XRD analysis was performed on this activated alumina, a peak derived from boehmite was observed in a broad chart, and the integrated intensity of the peak at 2θ = 14.39 ° was 98 cps · deg. The integrated intensity of was 0.07 with respect to the integrated intensity of a broad peak existing over 2θ = 10 to 60 deg. Therefore, this activated alumina can be said to be amorphous alumina because it mainly has an amorphous bulk structure and a very small amount of boehmite phase is mixed. The 0 / Al element ratio on the surface of the activated alumina was 1.54.
The separator for non-aqueous secondary batteries of this invention was obtained like Example 2-1, except the point which used this activated alumina as a porous filler.
[Example 2-8]
A separator for a non-aqueous secondary battery of the present invention was obtained in the same manner as in Example 2-7, except that the dispersion was applied to only one surface of a polyethylene microporous membrane to form a porous layer.
[Comparative Example 2-1]
Instead of the porous filler used in Example 2-1, the average particle diameter was 0.6 μm and the specific surface area was 6 m as an inorganic filler. ² A non-aqueous secondary battery separator was produced in the same manner as in Example 2-1, except that / g of α-alumina (manufactured by Showa Denko: AL160SG-3) was applied.
[Comparative Example 2-2]
Instead of the porous filler used in Example 1, an inorganic filler has an average particle diameter of 0.6 μm and a specific surface area of 15 m. ² A non-aqueous secondary battery separator was produced in the same manner as in Example 2-1, except that / g boehmite (manufactured by Daimei Chemical Co., Ltd .: C06) was applied.
[Comparative Example 2-3]
Aluminum hydroxide (manufactured by Showa Denko; H-43M) was heat-treated at 205 ° C., average particle size 0.8 μm, specific surface area 30 m ² / G of activated alumina was obtained. In addition, when the crystal structure of this activated alumina was analyzed by XRD, a broad peak derived from the amorphous structure was not confirmed, and a peak derived from the gibbsite was clearly observed. Therefore, the bulk structure was mainly gibbsite, It turned out not to be alumina. A separator for a non-aqueous secondary battery was obtained in the same manner as in Example 2-1, except that the porous filler was changed to this activated alumina.
[Comparative Example 2-4]
As polyethylene powder, GUR2126 (weight average molecular weight 41.50 million, melting point 141 ° C.) and GRX143 (weight average molecular weight 560,000, melting point 135 ° C.) manufactured by Ticona were used. The liquid paraffin (manufactured by Matsumura Oil Research Co., Ltd .; Smoyl P-350P; boiling point 480 ° C.) and decalin so that GUR2126 and GURX143 are 1: 9 (weight ratio) and the polyethylene concentration is 15% by weight. A polyethylene solution was prepared by dissolving in a mixed solvent. The composition of the polyethylene solution is polyethylene: liquid paraffin: decalin = 30: 45: 25 (weight ratio).
A slurry was prepared by dispersing the polyethylene solution in a weight ratio such that polyethylene: zeolite (HSZ-500KOA; manufactured by Tosoh Corporation) = 50: 50. Here, this zeolite has an average particle diameter of 3 μm and a specific surface area of 290 m. ² / G.
This slurry was extruded from a die at 148 ° C. and cooled in a water bath to prepare a gel tape (base tape). The base tape was dried at 60 ° C. for 8 minutes and at 95 ° C. for 15 minutes, and the base tape was biaxially stretched by successively performing longitudinal stretching and transverse stretching. Here, the longitudinal stretching was performed at a stretching ratio of 5.5 times and a stretching temperature of 90 ° C., the transverse stretching was performed at a stretching ratio of 11.0 times, and the stretching temperature was 105 ° C. After stretching, heat setting was performed at 125 ° C. Next, this was immersed in a methylene chloride bath to extract liquid paraffin and decalin. Then, it dried at 50 degreeC and annealed at 120 degreeC, and obtained the polyethylene microporous film (non-aqueous secondary battery separator) containing a porous filler.
[Comparative Example 2-5]
Conex (registered trademark; manufactured by Teijin Techno Products), which is polymetaphenylene isophthalamide, was used as the meta-type wholly aromatic polyamide. Conex solution was prepared by dissolving in 6% by weight of Conex in dimethylacetamide (DMAc): tripropylene glycol (TPG) = 60: 40 (weight ratio).
Two Mayer bars were placed against each other, and an appropriate amount of the Conex solution was placed between them. The polyethylene microporous membrane containing the porous filler prepared in Comparative Example 2-4 was passed between Mayer bars on which the Conex solution was placed, and the Conex solution was applied to both sides of the polyethylene microporous membrane. Here, the clearance between the Mayer bars was 30 μm, and the number of the Mayer bars was # 6. This is immersed in a coagulating liquid having a weight ratio of water: DMAc: TPG = 70: 18: 12 (weight ratio) of 30 ° C., then washed with water, dried, and a polyethylene microporous film containing a porous filler A porous layer made of Conex was formed on the front and back surfaces of the non-aqueous secondary battery separator.

[Cycle characteristic evaluation]
Next, a non-aqueous secondary battery was manufactured as follows for a separator in which a heat-resistant porous layer was formed on one or both sides of a porous substrate, and it was examined whether there was a difference in cycle characteristics.
Lithium cobalt oxide (LiCoO ₂ NIPPON CHEMICAL INDUSTRIES CO., LTD.) 89.5 parts by weight of powder, acetylene black (manufactured by Denki Kagaku Kogyo; trade name Denka Black) 4.5 parts by weight, polyvinylidene fluoride (manufactured by Kureha Chemical Co., Ltd.) 6 parts by weight These were kneaded using an N-methyl-2pyrrolidone solvent to prepare a slurry. The obtained slurry was applied onto an aluminum foil having a thickness of 20 μm, dried and pressed to obtain a positive electrode having a thickness of 100 μm.
87 parts by weight of mesophase carbon microbeads (MCMB: Osaka Gas Chemical Co., Ltd.) powder, 3 parts by weight of acetylene black (manufactured by Denki Kagaku Kogyo; trade name Denka Black), 10 parts by weight of polyvinylidene fluoride (manufactured by Kureha Chemical Co., Ltd.) Thus, these were knead | mixed using the N-methyl-2 pyrrolidone solvent, and the slurry was produced. The obtained slurry was applied onto a copper foil having a thickness of 18 μm, dried and pressed to obtain a negative electrode having a thickness of 90 μm.
The positive electrode and the negative electrode were opposed to each other through a separator. This was impregnated with an electrolytic solution and sealed in an exterior made of an aluminum laminate film to produce a non-aqueous secondary battery. Here, the electrolyte is 1M LiPF ₆ Ethylene carbonate / ethyl methyl carbonate (3/7 weight ratio) (manufactured by Kishida Chemical Co., Ltd.) was used.
Here, separators of Example 2-7 and Example 2-8 were used, and batteries of Examples 2-9 to 2-11 shown in Table 6 were produced.
Evaluation of cycle characteristics is 1C 4.2V 2 hours constant current / constant voltage charge, 1C, charge / discharge with constant current discharge of 2.75V cutoff, 300 cycles when the first cycle capacity is used as a reference The eye capacity retention rate was used as an index of cycle characteristics. The temperature at the time of measurement was 30 ° C. The results are shown in Table 6.

From the results of Table 6, it was found that the configuration in which the heat-resistant porous layer was formed on both sides of the porous substrate was superior in capacity retention rate than the configuration on one side. It was also found that the capacity retention rate was higher when the polyethylene microporous membrane was arranged on the negative electrode side even with a single-sided configuration.
(3) Effect of special activated alumina in the third form
Hereinafter, among the third forms of the present invention, the specific surface area is 300 to 1000 m. ² The structure using activated alumina of / g is examined.
The measurement methods applied in the following examples are as follows. In addition, about the measuring method of the average particle diameter of an inorganic filler, a specific surface area, a crystal structure, and element ratio, it is the same as that of the case which concerns on the 1st and 2nd form mentioned above.
[Measurement of true density of alumina]
The true density of the alumina used in the following Examples and Comparative Examples was determined with a micro ultra pycnometer (MUSPY-21T manufactured by Yuasa Ionics). Helium gas was used for the measurement.
[Example 3-1]
(I) Production of PE microporous membrane
As polyethylene powder, GUR2126 (weight average molecular weight 41.50 million, melting point 141 ° C.) and GRX143 (weight average molecular weight 560,000, melting point 135 ° C.) manufactured by Ticona were used. GUR2126 and GURX143 are made to have a ratio of 1: 9 (weight ratio) and liquid paraffin (manufactured by Matsumura Oil Research Co., Ltd .; Smoyl P-350P; boiling point 480 ° C.) and decalin so that the polyethylene concentration becomes 30% by weight. A polyethylene solution was prepared by dissolving in a mixed solvent. The composition of this polyethylene solution was polyethylene: liquid paraffin: decalin = 30: 45: 25 (weight ratio).
This polyethylene solution was extruded from a die at 148 ° C. and cooled in a water bath to prepare a gel tape (base tape). The base tape was dried at 60 ° C. for 8 minutes and at 95 ° C. for 15 minutes, and then the base tape was stretched by biaxial stretching that was performed in the order of longitudinal stretching and lateral stretching. Here, the longitudinal stretching was 5.5 times, the stretching temperature was 90 ° C., the transverse stretching was 11.0 times the stretching ratio, and the stretching temperature was 105 ° C. After transverse stretching, heat setting was performed at 125 ° C. Next, this was immersed in a methylene chloride bath to extract liquid paraffin and decalin. Then, it dried at 50 degreeC and annealed at 120 degreeC, and obtained PE microporous film.
(Ii) Production of polymetaphenylene isophthalamide
In a reaction vessel equipped with a thermometer, a stirrer, and a raw material inlet, 753 g of NMP having a moisture content of 100 ppm or less was put, 85.2 g of metaphenylenediamine and 0.5 g of aniline were dissolved in this NMP, and cooled to 0 ° C. . To this cooled diamine solution, 160.5 g of isophthalic acid chloride was gradually added with stirring to react. This reaction increased the temperature of the solution to 70 ° C. After the change in viscosity stopped, 58.4 g of calcium hydroxide powder was added and stirred for another 40 minutes to complete the reaction, and the polymerization solution was taken out and reprecipitated in water to obtain 184.0 g of polymetaphenylene isophthalamide. .
(Iii) Production of activated alumina
Aluminum hydroxide (manufactured by Showa Denko; H-43M) was heat-treated at 280 ° C., average particle diameter 0.8 μm, specific surface area 400 m ² / G of activated alumina was obtained. The true density of this activated alumina is 3.1 g / cm. ² Met. In addition, when XRD analysis was performed, a peak derived from boehmite was observed in a broad chart, and the integrated intensity of the peak at 2θ = 14.39 ° was 98 cps · deg. The intensity was 0.07 with respect to the integrated intensity of a broad peak existing over 2θ = 10 to 60 deg. Therefore, this activated alumina can be said to be amorphous alumina because it mainly has an amorphous bulk structure and a very small amount of boehmite phase is mixed.
(Iv) Manufacture of laminated separator
The polymetaphenylene isophthalamide obtained as described above and activated alumina were prepared so that the weight ratio was 40:60, and the polymetaphenylene isophthalamide concentration was 5.5% by weight. Dimethylacetamide (DMAc) and tripropylene glycol (TPG) were mixed in a mixed solvent having a weight ratio of 50:50 to obtain a coating slurry.
The coating slurry was applied to both sides of the PE film by placing an appropriate amount of the coating slurry on a Meyer bar and passing the PE film obtained as described above between a pair of Meyer bars. This was immersed in a coagulation liquid having a weight ratio of water: DMAc: TPG = 50: 25: 25 and 40 ° C. Thereafter, the obtained film was washed with water and dried. Thereby, the laminated separator with which the heat resistant porous layer was coated was obtained.
(V) Manufacture of positive electrode
Lithium cobalt oxide (LiCoO ₂ 89.5 parts by weight of powder, manufactured by Nippon Chemical Industry Co., Ltd., 4.5 parts by weight of acetylene black (Denka Black, manufactured by Denki Kagaku Kogyo Co., Ltd.), and 6 wt. A positive electrode paste was prepared using an NMP solution of 6% by weight of polyvinylidene fluoride so as to be part. The obtained paste was applied onto an aluminum foil having a thickness of 20 μm, dried and pressed to obtain a positive electrode having a thickness of 97 μm.
(Vi) Manufacture of negative electrode
As a negative electrode active material, 87 parts by weight of mesophase carbon microbeads (MCMB, manufactured by Osaka Gas Chemical Co., Ltd.), 3 parts by weight of acetylene black and 6 parts by weight of polyfluorinated so that the dry weight of polyvinylidene fluoride is 10 parts by weight. A negative electrode paste was prepared using an NMP solution of vinylidene. The obtained paste was applied onto a copper foil having a thickness of 18 μm, dried and pressed to prepare a negative electrode having a thickness of 90 μm.
(Vii) Preparation of non-aqueous electrolyte
LiPF was added to a solution in which ethylene carbonate and ethyl methyl carbonate were mixed at a weight ratio of 3: 7. ₆ Was dissolved so as to be 1 mol / L.
(Viii) Manufacture of non-aqueous secondary batteries
The positive electrode and negative electrode obtained as described above were opposed to each other through a laminated separator. This was impregnated with a non-aqueous electrolyte and sealed in an exterior made of an aluminum laminate film to produce a non-aqueous secondary battery.
[Comparative Example 3-1]
As polyethylene powder, GUR2126 (weight average molecular weight 41.50 million, melting point 141 ° C.) and GRX143 (weight average molecular weight 560,000, melting point 135 ° C.) manufactured by Ticona were used. GUR2126 and GURX143 are made to be 1: 9 (weight ratio) and liquid paraffin (manufactured by Matsumura Oil Research Co., Ltd .; Smoyl P-350P; boiling point 480 ° C.) and decalin so that the polyethylene concentration becomes 30% by weight. Dissolved in a mixed solvent and further used as a filler with an average particle size of 0.5 μm and a specific surface area of 7 m ² / G of α-alumina (AL-160SG-3; manufactured by Showa Denko) was dispersed to prepare a polyethylene solution. The composition of this polyethylene solution was polyethylene: alumina: liquid paraffin: decalin = 30: 10: 55: 30 (weight ratio).
This polyethylene solution was extruded from a die at 148 ° C. and cooled in a water bath to prepare a gel tape (base tape). The base tape was dried at 60 ° C. for 8 minutes and at 95 ° C. for 15 minutes, and then the base tape was stretched by biaxial stretching that was performed in the order of longitudinal stretching and lateral stretching. Here, the longitudinal stretching was 5.5 times, the stretching temperature was 90 ° C., the transverse stretching was 11.0 times the stretching ratio, and the stretching temperature was 105 ° C. After transverse stretching, heat setting was performed at 125 ° C. Next, this was immersed in a methylene chloride bath to extract liquid paraffin and decalin. Then, it dried at 50 degreeC and annealed at 120 degreeC, and obtained the separator which consists of PE microporous films.
A nonaqueous secondary battery was produced in the same manner as in Example 3-1, except that this separator was used.
[Comparative Example 3-2]
Aluminum hydroxide (made by Showa Denko; H-43M) was heat-treated at 220 ° C., average particle size 0.8 μm, specific surface area 60 m ² / G of activated alumina was obtained. The true density of this activated alumina is 2.5 g / cm. ² Met. Further, in XRD, a broad peak derived from the amorphous structure was not confirmed, and a peak derived from gibbsite was clearly observed. Therefore, the bulk structure of this activated alumina was mainly gibbsite.
A nonaqueous secondary battery was obtained in the same manner as in Comparative Example 3-1, except that this activated alumina was used as an inorganic filler.
[Comparative Example 3-3]
Aluminum hydroxide (Showa Denko; H-43M) was heat-treated at 240 ° C., average particle diameter 0.8 μm, specific surface area 200 m ² / G of activated alumina was obtained. The true density of this activated alumina is 2.6 g / cm. ² Met. Further, when XRD analysis was performed on this activated alumina, a peak derived from gibbsite was observed, the integrated intensity of the peak at 2θ = 18.27 ° was 371 cps · deg, and the integrated intensity of this main peak was 2θ = 10. It was 0.35 with respect to the integrated intensity | strength of the broad peak which exists over -60deg. Therefore, the bulk structure of this activated alumina was mainly gibbsite.
A nonaqueous secondary battery was obtained in the same manner as in Comparative Example 3-1, except that this activated alumina was used as an inorganic filler.
[Comparative Example 3-4]
As an inorganic filler, an average particle diameter of 2 μm and a specific surface area of 400 m ² A nonaqueous secondary battery was obtained in the same manner as Comparative Example 3-1, except that / g of zeolite (HSZ-980HOA; manufactured by Tosoh Corporation) was used.
[Comparative Example 3-5]
As an inorganic filler, an average particle diameter of 2 μm and a specific surface area of 300 m ² A nonaqueous secondary battery was obtained in the same manner as Comparative Example 3-1, except that / g of silica (manufactured by Tokai Chemical Industry Co., Ltd .; ML-384) was used.
[Comparative Example 3-6]
Activated carbon (manufactured by Kansai Thermal Chemical Co., Ltd .; MSP-20) is subjected to wet pulverization (2 mm zirconia bead mill) using dimethylacetamide (DMAc) as a dispersion solvent, whereby an average particle diameter of 0.6 μm and a specific surface area of 1600 m ² / G of activated carbon was obtained.
A nonaqueous secondary battery was obtained in the same manner as Comparative Example 3-1, except that this activated carbon was used as an inorganic filler.
[Measurement of capacity maintenance ratio]
About the non-aqueous secondary battery of the Example produced as mentioned above and a comparative example, in a 60 degreeC thermostat, a charge / discharge measuring apparatus (HJ-101SM6 by Hokuto Denko Co., Ltd.) was used, and charge / discharge characteristics were measured. did. Regarding charging / discharging conditions, charging is performed at 0.2 C to 4.2 V for 8 hours, discharging is performed at 0.2 C at 2.75 V, and the capacity maintenance rate is the discharge at the time of 500 cycles with respect to the initial discharge capacity The capacity ratio. Table 7 shows the measurement results.

As can be seen from Table 7, the specific surface area is 300 to 1000 m. ² Example 3-1 using activated alumina / g of activated alumina having a specific surface area outside the above range (Comparative Examples 3-2 and 3-3), α-alumina (Comparative Example 3-1), and others Compared to the porous filler (Comparative Examples 3-3 to 3-6), the capacity retention rate after 500 cycle characteristic tests is remarkably excellent. This has a specific surface area of 300-1000m ² This is considered to be because / g of activated alumina lowered the activity of HF in the battery. In addition, although the filler was applied in the heat-resistant porous layer in a composite separator in an Example and there was a difference that the filler was applied in the PE separator in the comparative example, both applied the filler in the separator. Therefore, the influence of the above difference on the capacity maintenance rate is not so great.
(4) Effect of amorphous alumina in the fourth form
Hereinafter, the configuration using amorphous alumina in the fourth embodiment of the present invention will be examined. Various measurement methods are as described above.
[Example 4-1]
A nonaqueous secondary battery of Example 4-1 was produced in the same manner as Example 3-1 described above.
[Comparative Example 4-1]
As polyethylene powder, GUR2126 (weight average molecular weight 41.50 million, melting point 141 ° C.) and GRX143 (weight average molecular weight 560,000, melting point 135 ° C.) manufactured by Ticona were used. GUR2126 and GURX143 are made to be 1: 9 (weight ratio) and liquid paraffin (manufactured by Matsumura Oil Research Co., Ltd .; Smoyl P-350P; boiling point 480 ° C.) and decalin so that the polyethylene concentration becomes 30% by weight. Dissolved in a mixed solvent and further used as a filler with an average particle size of 0.5 μm and a specific surface area of 7 m ² / G of α-alumina (AL-160SG-3; manufactured by Showa Denko) was dispersed to prepare a polyethylene solution. The composition of this polyethylene solution was polyethylene: alumina: liquid paraffin: decalin = 30: 10: 55: 30 (weight ratio).
This polyethylene solution was extruded from a die at 148 ° C. and cooled in a water bath to prepare a gel tape (base tape). The base tape was dried at 60 ° C. for 8 minutes and at 95 ° C. for 15 minutes, and then the base tape was stretched by biaxial stretching that was performed in the order of longitudinal stretching and lateral stretching. Here, the longitudinal stretching was 5.5 times, the stretching temperature was 90 ° C., the transverse stretching was 11.0 times the stretching ratio, and the stretching temperature was 105 ° C. After transverse stretching, heat setting was performed at 125 ° C. Next, this was immersed in a methylene chloride bath to extract liquid paraffin and decalin. Then, it dried at 50 degreeC and annealed at 120 degreeC, and obtained the separator which consists of PE microporous films.
A nonaqueous secondary battery was produced in the same manner as in Example 3-1 described above except that this separator was used.
[Comparative Example 4-2]
As an inorganic filler, average particle diameter 0.6 μm, specific surface area 15 m ² A nonaqueous secondary battery was obtained in the same manner as Comparative Example 4-1, except that / g nonporous alumina (manufactured by Daimei Chemical Co., Ltd .; C06) was used. When this alumina was subjected to XRD analysis, a clear peak derived from boehmite was observed.
[Comparative Example 4-3]
As an inorganic filler, average particle diameter 0.8μm, specific surface area 7m ² A nonaqueous secondary battery was obtained in the same manner as Comparative Example 4-1, except that / g nonporous aluminum hydroxide (manufactured by Showa Denko; H-43M) was used. When this aluminum hydroxide was subjected to XRD analysis, a clear peak derived from gibbsite was observed.
[Measurement of capacity maintenance ratio]
About the non-aqueous secondary battery of the Example produced as mentioned above and a comparative example, in a 60 degreeC thermostat, a charge / discharge measuring apparatus (HJ-101SM6 by Hokuto Denko Co., Ltd.) was used, and charge / discharge characteristics were measured. did. Regarding charging / discharging conditions, charging is performed at 0.2 C to 4.2 V for 8 hours, discharging is performed at 0.2 C at 2.75 V, and the capacity retention rate is discharging at 400 cycles with respect to the initial discharging capacity. The capacity ratio. Table 8 shows the measurement results.

As can be seen from Table 8, Example 4-1 using amorphous alumina includes α-alumina (Comparative Example 4-1), boehmite (Comparative Example 4-2), gibbsite (Comparative Example 4-3) and the like. Compared to the alumina-based filler, the capacity retention rate after 400 cycle characteristic tests is remarkably superior. This is presumably because amorphous alumina lowered the activity of HF in the battery.
(5) Example according to the fifth embodiment
Examples according to the fifth aspect of the present invention will be described below. The average particle diameter, specific surface area, true density, crystal structure and element ratio, and film thickness measuring method of the inorganic filler are as described above.
[Example 5-1]
(I) Production of activated alumina
Activated alumina A was produced in the same manner as in Example 3-1.
(Ii) Production of positive electrode, negative electrode and non-aqueous electrolyte
A positive electrode, a negative electrode, and a nonaqueous electrolyte were also produced in the same manner as in Example 3-1.
(Iii) Manufacture of separators
As polyethylene powder, GUR2126 (weight average molecular weight 41.50 million, melting point 141 ° C.) and GRX143 (weight average molecular weight 560,000, melting point 135 ° C.) manufactured by Ticona were used. GUR2126 and GURX143 are made to be 1: 9 (weight ratio) and liquid paraffin (manufactured by Matsumura Oil Research Co., Ltd .; Smoyl P-350P; boiling point 480 ° C.) and decalin so that the polyethylene concentration becomes 30% by weight. It was dissolved in a mixed solvent, and the activated alumina A was dispersed as an inorganic filler to prepare a polyethylene solution. The composition of this polyethylene solution was polyethylene: inorganic filler: liquid paraffin: decalin = 30: 10: 55: 30 (weight ratio).
This polyethylene solution was extruded from a die at 148 ° C. and cooled in a water bath to prepare a gel tape (base tape). The base tape was dried at 60 ° C. for 8 minutes and at 95 ° C. for 15 minutes, and then the base tape was stretched by biaxial stretching that was performed in the order of longitudinal stretching and lateral stretching. Here, the longitudinal stretching was 5.5 times, the stretching temperature was 90 ° C., the transverse stretching was 11.0 times the stretching ratio, and the stretching temperature was 105 ° C. After transverse stretching, heat setting was performed at 125 ° C. Next, this was immersed in a methylene chloride bath to extract liquid paraffin and decalin. Then, it dried at 50 degreeC and annealed at 120 degreeC, and obtained the PE separator which consists of a polyethylene microporous film.
(Iv) Non-aqueous secondary battery
The positive electrode and negative electrode obtained as described above were opposed to each other through a separator. This was impregnated with a non-aqueous electrolyte and sealed in an outer package made of an aluminum laminate film to produce a non-aqueous secondary battery of an example of the present invention.
[Example 5-2]
Aluminum hydroxide (Showa Denko; H-43M) was heat-treated at 260 ° C., average particle size 0.8 μm, specific surface area 350 m ² / G, true density 3.0 g / cm ³ Activated alumina B was obtained. As a result of XRD structural analysis of this activated alumina B, a peak derived from boehmite was slightly observed in the broad chart, and the integrated intensity of the peak at 2θ = 14.40 ° was 83 cps · deg. The integrated intensity was 0.05 with respect to the integrated intensity of the broad peak existing over 2θ = 10 to 60 deg. Therefore, this activated alumina mainly has an amorphous bulk structure and a very small amount of boehmite phase was mixed.
A nonaqueous secondary battery of the present invention was obtained in the same manner as in Example 5-1, except that this activated alumina B was used as an inorganic filler.
[Example 5-3]
Polymer (weight average molecular weight 400000) copolymerized at a molar ratio of vinylidene fluoride: hexafluoropropylene: chlorotrifluoroethylene = 97: 1: 2, the above-mentioned activated alumina A, dimethylacetamide (DMAc), and tri The dope was obtained by sufficiently stirring so that the weight ratio of propylene glycol (TPG) was polymer: active alumina: DMAc: TPG = 12: 4: 49: 35. Then, a nonwoven fabric composed of PET short fibers and polyolefin short fibers was sufficiently impregnated with the dope, solidified in a coagulation bath, washed and dried. This obtained the composite separator (PVdF / nonwoven fabric separator) of polyvinylidene fluoride and the nonwoven fabric. The composition of the coagulation bath was water: dimethylacetamide: tripropylene glycol = 57: 30: 13 by weight ratio. And the non-aqueous secondary battery of this invention was obtained like Example 5-1, except having used PVdF / nonwoven fabric separator instead of PE separator.
[Example 5-4]
A coating solution was prepared by mixing 5 parts by weight of polyvinylidene fluoride, 1 part by weight of activated alumina A, and 94 parts by weight of DMAc and stirring sufficiently to obtain a uniform solution. And after apply | coating said coating liquid to the single side | surface of a polypropylene separator (Celgard # 2400) with the bar coater, this was dried at 60 degreeC. As a result, a polypropylene separator (PVdF / PP separator) having a coating layer having a thickness of 4 μm was obtained. And the nonaqueous secondary battery of this invention was obtained like Example 5-1, except having used the PVdF / PP separator so that the coating layer might contact | connect a positive electrode instead of PE separator.
[Example 5-5]
A nonaqueous secondary battery of the present invention was obtained in the same manner as in Example 5-4 except that the PVdF / PP separator obtained in Example 5-4 was used so that the coating layer was in contact with the negative electrode.
[Example 5-6]
Lithium manganate (LiMn ₂ O ₄ 89.5 parts by weight of powder (manufactured by JGC Chemical Co., Ltd.), 4.5 parts by weight of acetylene black (DENKA BLACK, manufactured by Denki Kagaku Kogyo Co., Ltd.) and 6 parts by weight of dry weight of polyvinylidene fluoride (manufactured by CLEA Chemical Industries, Ltd.) Thus, a positive electrode paste was prepared using an NMP solution of 6% by weight of polyvinylidene fluoride. The obtained paste was applied onto an aluminum foil having a thickness of 20 μm, dried and pressed to obtain a positive electrode having a thickness of 70 μm.
A nonaqueous secondary battery of the present invention was obtained in the same manner as in Example 5-1, except that this positive electrode was used.
[Example 5-7]
Lithium cobalt oxide (LiCoO ₂ , Manufactured by Nippon Chemical Industry Co., Ltd.) 89.5 parts by weight of powder, 4.5 parts by weight of acetylene black (Denka Black, manufactured by Denki Kagaku Kogyo Co., Ltd.), 3 parts by weight of activated alumina A and polyvinylidene fluoride (manufactured by Claire Chemical Industries, Ltd.) A positive electrode paste was prepared using 6 wt% of an NMP solution of polyvinylidene fluoride so that the dry weight of 6) was 6 parts by weight. The obtained paste was applied onto an aluminum foil having a thickness of 20 μm, dried and pressed to obtain a positive electrode having a thickness of 97 μm.
As polyethylene powder, GUR2126 (weight average molecular weight 41.50 million, melting point 141 ° C.) and GRX143 (weight average molecular weight 560,000, melting point 135 ° C.) manufactured by Ticona were used. GUR2126 and GURX143 are made to have a ratio of 1: 9 (weight ratio) and liquid paraffin (manufactured by Matsumura Oil Research Co., Ltd .; Smoyl P-350P; boiling point 480 ° C.) and decalin so that the polyethylene concentration becomes 30% by weight. A polyethylene solution was prepared by dissolving in a mixed solvent. The composition of this polyethylene solution was polyethylene: liquid paraffin: decalin = 30: 45: 25 (weight ratio).
This polyethylene solution was extruded from a die at 148 ° C. and cooled in a water bath to prepare a gel tape (base tape). The base tape was dried at 60 ° C. for 8 minutes and at 95 ° C. for 15 minutes, and then the base tape was stretched by biaxial stretching that was performed in the order of longitudinal stretching and lateral stretching. Here, the longitudinal stretching was 5.5 times, the stretching temperature was 90 ° C., the transverse stretching was 11.0 times the stretching ratio, and the stretching temperature was 105 ° C. After transverse stretching, heat setting was performed at 125 ° C. Next, this was immersed in a methylene chloride bath to extract liquid paraffin and decalin. Then, it dried at 50 degreeC and annealed at 120 degreeC, and obtained the PE separator which consists of a polyethylene microporous film.
A nonaqueous secondary battery of the present invention was obtained in the same manner as in Example 5-1, except that the positive electrode and PE separator produced as described above were used.
[Example 5-8]
As negative electrode active material, 87 parts by weight of mesophase carbon microbeads (MCMB, manufactured by Osaka Gas Chemical Co., Ltd.), 3 parts by weight of acetylene black, 3 parts by weight of activated alumina A, and 10 parts by weight of dry weight of polyvinylidene fluoride As described above, a negative electrode agent paste was prepared using an NMP solution of 6% by weight of polyvinylidene fluoride. The obtained paste was applied onto a copper foil having a thickness of 18 μm, dried and pressed to produce a negative electrode having a thickness of 91 μm.
A nonaqueous secondary battery of the present invention was obtained in the same manner as in Example 5-1, except that this negative electrode was used and the PE separator in Example 5-7 was used.
[Example 5-9]
The coating liquid prepared in Example 5-4 was applied to the active material side of the positive electrode manufactured in Example 5-1 using a bar coater, and then dried at 60 ° C. As a result, a positive electrode having a coating layer (positive electrode surface layer) having a thickness of 4 μm was obtained.
A nonaqueous secondary battery of the present invention was obtained in the same manner as in Example 5-1, except that this positive electrode was used and the PE separator in Example 5-7 was used.
[Example 5-10]
The coating liquid prepared in Example 5-4 was applied to the active material side of the negative electrode manufactured in Example 5-1 using a bar coater, and then dried at 60 ° C. As a result, a negative electrode having a coating layer (negative electrode surface layer) having a thickness of 4 μm was obtained.
A nonaqueous secondary battery of the present invention was obtained in the same manner as in Example 5-1, except that this negative electrode was used and the PE separator in Example 5-7 was used.
[Comparative Example 5-1]
A non-aqueous secondary battery was obtained in the same manner as in Example 5-1, except that the PE separator in Example 5-7 was used.
[Comparative Example 5-2]
Weight of copolymer (weight average molecular weight 400000), dimethylacetamide (DMAc), and tripropylene glycol (TPG) copolymerized at a molar ratio of vinylidene fluoride: hexafluoropropylene: chlorotrifluoroethylene = 97: 1: 2. The dope was obtained by sufficiently stirring so that the ratio was polymer: DMAc: TPG = 12: 48: 40. Then, a nonwoven fabric composed of PET short fibers and polyolefin short fibers was sufficiently impregnated with the above dope, solidified in a coagulation bath, washed with water and dried. Thereby, a separator (PVdF / nonwoven fabric separator) in which polyvinylidene fluoride was combined with a nonwoven fabric was obtained. The composition of the coagulation bath was water: dimethylacetamide: tripropylene glycol = 57: 30: 13 by weight ratio.
A nonaqueous secondary battery was obtained in the same manner as in Example 5-1, except that this PVdF / nonwoven fabric separator was used.
[Comparative Example 5-3]
A non-aqueous secondary battery was obtained in the same manner as in Comparative Example 1 except that a polypropylene separator (Celguard # 2400) was used instead of the PE separator.
[Comparative Example 5-4]
As an inorganic filler, average particle size 0.5 μm, specific surface area 7 m ² A non-aqueous secondary battery was obtained in the same manner as in Example 5-1, except that / g of α-alumina (AL-160SG-3; manufactured by Showa Denko) was used.
[Comparative Example 5-5]
Aluminum hydroxide (made by Showa Denko; H-43M) was heat-treated at 220 ° C., average particle size 0.8 μm, specific surface area 60 m ² / G, true density 2.5 g / cm ³ Of activated alumina C was obtained. When the crystal structure of this activated alumina C was analyzed by XRD, a broad peak derived from the amorphous structure was not confirmed, and a peak derived from the gibbsite was clearly observed. Therefore, the bulk structure of the activated alumina C was mainly gibbsite. I found out.
A nonaqueous secondary battery was obtained in the same manner as in Example 5-1, except that this activated alumina C was used as an inorganic filler.
[Comparative Example 5-6]
Aluminum hydroxide (Showa Denko; H-43M) was heat-treated at 240 ° C., average particle diameter 0.8 μm, specific surface area 200 m ² / G, true density 2.6 g / cm ³ Of activated alumina D was obtained. When the crystal structure of this activated alumina D was analyzed by XRD, a peak derived from gibbsite was observed, the integrated intensity of the peak at 2θ = 18.27 ° was 371 cps · deg, and the integrated intensity of this main peak was 2θ = It was 0.35 with respect to the integrated intensity | strength of the broad peak which exists over 10-60deg. Therefore, it turned out that activated alumina D contains gibbsite in the bulk structure.
A nonaqueous secondary battery was obtained in the same manner as in Example 5-1, except that this activated alumina D was used as an inorganic filler.
[Comparative Example 5-7]
As an inorganic filler, an average particle diameter of 2 μm and a specific surface area of 400 m ² / G zeolite (HSZ-980HOA; manufactured by Tosoh Corporation) was used in the same manner as in Example 5-1, to obtain a non-aqueous secondary battery.
[Comparative Example 5-8]
Without using activated alumina as an inorganic filler, the average particle size is 2 μm and the specific surface area is 300 m. ² A non-aqueous secondary battery was obtained in the same manner as in Example 1 except that / g of silica (manufactured by Tokai Chemical Industry; ML-384) was used.
[Comparative Example 5-9]
Activated carbon (manufactured by Kansai Thermal Chemical Co., Ltd .; MSP-20) is subjected to wet pulverization (2 mm zirconia bead mill) using dimethylacetamide (DMAc) as a dispersion solvent, whereby an average particle diameter of 0.6 μm and a specific surface area of 1600 m ² / G of activated carbon was obtained.
A nonaqueous secondary battery was obtained in the same manner as in Example 5-1, except that this activated carbon was used as an inorganic filler.
[Comparative Example 5-10]
A nonaqueous secondary battery was obtained in the same manner as in Comparative Example 5-1, except that the positive electrode produced in Example 5-6 was used.
[Measurement of capacity maintenance ratio]
About the non-aqueous secondary battery of the Example produced as mentioned above and a comparative example, in a 60 degreeC thermostat, a charge / discharge measuring apparatus (HJ-101SM6 by Hokuto Denko Co., Ltd.) was used, and charge / discharge characteristics were measured. did. Regarding charging / discharging conditions, charging is performed at 0.2 C to 4.2 V for 8 hours, discharging is performed at 0.2 C at 2.75 V, and the capacity maintenance rate is the discharge at the time of 500 cycles with respect to the initial discharge capacity The capacity ratio. Table 9 shows the measurement results.

[Performance evaluation]
As can be seen from the results of Examples 5-1 to 5-3 and Comparative Examples 5-1 to 5-3, all of the examples containing activated alumina in the separator showed excellent capacity retention of 70% or more. However, Comparative Examples 5-1 to 5-3 containing no activated alumina had a capacity retention rate as low as about 50%. Furthermore, although Examples 5-3 to 5-5 had a configuration in which a layer containing activated alumina was laminated on the separator, the capacity retention rate was excellent at 70% in all cases. Also, comparison between Examples 5-4 and 5-5 confirmed that it was effective if a layer containing activated alumina was present in at least one of the positive electrode and the negative electrode.
As can be seen from the results of Examples 5-1 to 5-2 and Comparative Examples 5-4 to 5-6, a tendency that the capacity retention rate was excellent as the specific surface area of the activated alumina increased was observed. And the specific surface area 200m of Comparative Example 5-6 ² / G, the effect is insufficient, and the specific surface area of Example 5-2 is 350 m. ² Since the effect was sufficiently confirmed with activated alumina / g, the specific surface area of activated alumina was 300 m. ² / G or more is preferred. In Comparative Examples 5-7 and 5-8, the specific surface area was 300 m instead of activated alumina. ² / G or more of zeolite and silica were used, but the capacity retention rate was 62% or less, and the activated alumina did not show the excellent effect. The specific surface area is 1600m ² In Comparative Example 5-9 using activated carbon of / g, the capacity retention rate was as low as 62% compared to Examples 5-1 to 5-2. From this, the specific surface area is 1000m ² / G or less, more preferably 500 m ² / G or less is suitable. On the other hand, the true density is 2.7 g / cm. ³ Below and 3.9 g / cm ³ Then, the capacity retention rate is low, and 2.8 to 3.3 g / cm. ³ It was found that better results could be obtained within this range. Based on the above, it can be estimated that the capacity maintenance rate has improved because the surface condition peculiar to activated alumina has reduced the activity of HF.
Even in Examples 5-6 and Comparative Example 5-10 in which the positive electrode active material was lithium manganate, excellent results were obtained with a capacity retention rate of 70% or more by using a separator containing activated alumina. In Comparative Example 5-10, since lithium manganate was used, the metal from the positive electrode was dissolved by HF rather than lithium cobaltate, so the capacity retention rate was considered to be as low as 42%.
When comparing the system containing activated alumina in the electrode and Examples 5-7 to 5-10, which are the system in which the layer of activated alumina is laminated on the electrode surface, the capacity retention rate is 70% or more in all Examples. Are better. As a result, it was confirmed that the location of the activated alumina was effective even if contained in the electrode or laminated on the electrode surface.
Summarizing the above performance evaluation results, in order to obtain a non-aqueous secondary battery with an excellent capacity retention rate, the specific surface area is 300 to 1000 m. ² As a result, it was found that / g of activated alumina is contained in a non-aqueous secondary battery, and the location of the activated alumina is not particularly limited.
[HF removal performance]
About the non-aqueous secondary battery of Examples 5-1 and 5-2 and Comparative Example 5-1, the capacity retention rate was measured, and then the battery was disassembled to extract a non-aqueous electrolyte. And content of HF in this electrolyte was measured.
Specifically, the HF content is measured by disassembling the non-aqueous secondary battery after measuring the capacity retention rate, and then in a predetermined amount of solution in which ethylene carbonate and ethyl methyl carbonate are mixed at a weight ratio of 3: 7. And left for 1 week to extract HF present in the battery with a solution. Then, titration was performed with an aqueous sodium hydroxide solution using bromothymol blue as an indicator, and the acid concentration in the extracted solution was determined. Finally, the value obtained by converting the obtained acid concentration per weight of the electrolyte used in the non-aqueous secondary battery was defined as the HF content (ppm). The measurement results for each sample are shown in Table 10 below. The HF content in the electrolyte before constituting the battery was 30 ppm.

As can be seen from the results in Table 10, it can be seen that in the battery using the activated alumina of Examples 5-1 and 5-2, the residual amount of HF is small as compared with Comparative Example 5-1. This is considered to be because HF is suitably captured by the activated alumina in the present invention.
(6) Example according to the sixth aspect
Examples according to the sixth aspect of the present invention will be described below. The average particle diameter, specific surface area, true density, crystal structure and element ratio, and film thickness measuring method of the inorganic filler are as described above.
[Example 6-1]
A non-aqueous secondary battery was produced in the same manner as in Example 5-1.
[Example 6-2]
A non-aqueous secondary battery was produced in the same manner as in Example 5-2 described above.
[Example 6-3]
A non-aqueous secondary battery was produced in the same manner as Example 5-3 described above.
[Example 6-4]
A non-aqueous secondary battery was produced in the same manner as in Example 5-4 described above.
[Example 6-5]
A non-aqueous secondary battery was produced in the same manner as in Example 5-5 described above.
[Example 6-6]
A non-aqueous secondary battery was produced in the same manner as in Example 5-9 described above.
[Example 6-7]
A nonaqueous secondary battery was produced in the same manner as in Example 5-10 described above.
[Comparative Example 6-1]
A non-aqueous secondary battery was produced in the same manner as Comparative Example 5-1 described above.
[Comparative Example 6-2]
A non-aqueous secondary battery was produced in the same manner as Comparative Example 5-2 described above.
[Comparative Example 6-3]
A non-aqueous secondary battery was produced in the same manner as Comparative Example 5-3 described above.
[Comparative Example 6-4]
Without using alumina A as an inorganic filler, the average particle size is 0.5 μm and the specific surface area is 7 m. ² / G nonporous alumina E (manufactured by Showa Denko; AL-160SG-3) was used in the same manner as in Example 6-1 to obtain a nonaqueous secondary battery. When this alumina E was subjected to XRD analysis, a clear peak derived from α-alumina was observed.
[Comparative Example 6-5]
Without using alumina A as an inorganic filler, the average particle diameter is 0.6 μm and the specific surface area is 15 m. ² A nonaqueous secondary battery was obtained in the same manner as in Example 6-1, except that / g nonporous alumina F (Daimei Chemical Industries; C06) was used. When this alumina F was subjected to XRD analysis, a clear peak derived from boehmite was observed.
[Comparative Example 6-6]
Without using alumina A as a filler, average particle diameter 0.8μm, specific surface area 7m ² A nonaqueous secondary battery was obtained in the same manner as in Example 6-1 except that / g nonporous aluminum hydroxide (Showa Denko; H-43M) was used. When this aluminum hydroxide was subjected to XRD analysis, a clear peak derived from gibbsite was observed.
[Comparative Example 6-7]
A non-aqueous secondary battery was produced in the same manner as Comparative Example 5-7 described above.
[Comparative Example 6-8]
Without using alumina A as an inorganic filler, the average particle diameter is 2 μm and the specific surface area is 600 m. ² A nonaqueous secondary battery was obtained in the same manner as in Example 6-1 except that / g of silica (manufactured by Tokai Chemical Industry Co., Ltd .; ML-644) was used.
[Comparative Example 6-9]
A non-aqueous secondary battery was produced in the same manner as Comparative Example 5-9 described above.
[Measurement of capacity maintenance ratio]
About the non-aqueous secondary battery of the Example produced as mentioned above and a comparative example, in a 60 degreeC thermostat, a charge / discharge measuring apparatus (HJ-101SM6 by Hokuto Denko Co., Ltd.) was used, and charge / discharge characteristics were measured. did. Regarding charging / discharging conditions, charging is performed at 0.2 C to 4.2 V for 8 hours, discharging is performed at 0.2 C at 2.75 V, and the capacity retention rate is discharging at 400 cycles with respect to the initial discharging capacity. The capacity ratio. Table 11 shows the measurement results.
[140 ° C oven test]
The non-aqueous secondary batteries of Examples and Comparative Examples produced as described above were charged at 0.2 C to 4.2 V for 8 hours, and then stored in an anti-drying dryer at 140 ° C. for 24 hours. As a result, when ignition was confirmed, it evaluated as x, and when ignition was not confirmed, it evaluated as (circle). The results are shown in Table 11.

[Performance evaluation]
In Table 11, from the results of Examples 6-1 to 6-2 and Comparative Examples 6-1 to 6-6, if the amorphous alumina is included in the separator, an excellent capacity retention rate of 70% or more is obtained. It can be seen that Comparative Examples 6-1 to 6-3 containing no filler had a capacity retention rate as low as 60% or less. Furthermore, according to the 140 ° C. oven test, ignition was not confirmed in Examples 6-1 to 6-2, but ignition was confirmed in Comparative Example 6-1, so Examples 6-1 to 6-2 were internal. It was found that the safety in short circuit is also excellent.
Further, in the comparison of the structures of alumina, Comparative Examples 6-4 to 6-6 having a structure other than amorphous had a capacity retention rate as low as 60% or less, and further ignition was confirmed in a 140 ° C. oven test. This indicates that amorphous alumina is excellent in both cycle characteristics and safety in internal short circuit.
Moreover, although zeolite, silica, and activated carbon were evaluated in Comparative Examples 6-7 to 6-9 as other inorganic fillers, the capacity retention rate was slightly over 60% compared to Examples 6-1 to 6-2. Low, ignition was confirmed in the 140 ° C. oven test. This also shows that amorphous alumina is excellent as the inorganic filler to be added.
When Examples 6-1 to 6-8 were compared as the location of alumina, the capacity retention rate was excellent at 70% or more in all cases, and the presence of amorphous alumina was positive because it did not ignite in the oven test. It was found that if it exists in any part between the negative electrode and the negative electrode, the cycle characteristics and safety due to internal short circuit are excellent.
[Measurement of heat shrinkage]
In order to investigate the cause of the presence or absence of ignition in the 140 ° C. oven test, the thermal contraction rate was measured for the separators of Examples 6-1 to 6-2 and Comparative Examples 6-1 and 6-4 to 6-9. .
Specifically, first, a separator as a sample was cut in a direction of 18 cm (MD direction) × 6 cm (TD). On the line that bisects the TD direction, points (point A, point B) of 2 cm and 17 cm from the top were marked. In addition, marks were placed at 1 cm and 5 cm from the left on the line that bisects the MD direction. This was clipped and hung in an oven adjusted to 105 ° C. and heat-treated for 30 minutes under no tension. The length between two points AB and the length between CDs were measured before and after the heat treatment, and the thermal shrinkage rate was obtained from the following two formulas. Table 12 summarizes the measurement results for each sample.
MD direction thermal shrinkage = (length between AB before heat treatment−length between AB after heat treatment) / (length between AB before heat treatment) × 100
TD direction thermal shrinkage = (length between CDs before heat treatment−length between CDs after heat treatment) / (length between CDs before heat treatment) × 100

From Table 12, Examples 6-1 to 6-2, which did not ignite in the 140 ° C. oven test, had a heat shrinkage ratio of 15% or less in the MD direction and 2% in the TD direction. On the other hand, Comparative Example 6-1 containing no filler, Comparative Examples 6-4 to 6-6 that are alumina or aluminum hydroxide other than amorphous, and Comparative Examples 6-7 that are fillers other than alumina In 6-9, the thermal shrinkage rate in the MD direction was 20% or more, and the thermal shrinkage rate in the TD direction was 3% or more, which was higher than those in Examples 6-1 to 6-2. From this, when the thermal shrinkage rate is 20% or more in the MD direction and 3% or more in the TD direction, the separator in the non-aqueous secondary battery breaks in the 140 ° C. oven test and causes ignition due to internal short circuit I can guess.
To summarize the above performance evaluation results, in order to obtain a non-aqueous secondary battery with excellent capacity maintenance rate and excellent safety that does not ignite in a 140 ° C. oven test, amorphous alumina is contained between the negative electrode and the positive electrode. The knowledge that it was good to be able to be made was able to be acquired.

Claims (6)

A porous membrane for a non-aqueous secondary battery comprising a heat resistant resin and an inorganic filler,
The inorganic filler is selected from the group consisting of zeolite, activated carbon, activated alumina, porous silica, and a porous filler obtained by heat-treating a metal hydroxide, and has an average particle size of 0.1 to 5.0 μm. And a porous filler having a specific surface area of 40 to 3000 m ² / g,
The heat-resistant resin is a wholly aromatic polyamide, polyimide, polyamideimide, polysulfone, polyketone, polyetherketone, polyethersulfone, polyetherimide, cellulose, or a combination of two or more of these. A porous membrane for a non-aqueous secondary battery. ^{2. The} porous membrane for a non-aqueous secondary battery according to claim 1, wherein the porous filler is activated alumina having a specific surface area of 300 to 1000 m ² / g.   A non-aqueous secondary battery comprising at least a positive electrode and a negative electrode,
  The porous film for a nonaqueous secondary battery according to claim 1 or 2 is formed on the surface of at least one of the positive electrode and the negative electrode, or the porous film for a nonaqueous secondary battery is used as a separator. A non-aqueous secondary battery characterized by that.   A separator for a non-aqueous secondary battery comprising a porous substrate and a heat-resistant porous layer containing a heat-resistant resin and an inorganic filler laminated on one or both surfaces of the porous substrate,
  The inorganic filler is selected from the group consisting of zeolite, activated carbon, activated alumina, porous silica, and a porous filler obtained by heat-treating a metal hydroxide, and has an average particle size of 0.1 to 5.0 μm. Yes, and specific surface area is 40-3000m ² / G porous filler,
  The heat-resistant resin is a wholly aromatic polyamide, polyimide, polyamideimide, polysulfone, polyketone, polyetherketone, polyethersulfone, polyetherimide, cellulose, or a combination of two or more of these.
  A separator for a non-aqueous secondary battery.   The porous filler has a specific surface area of 300 to 1000 m. ² The separator for non-aqueous secondary batteries according to claim 4, wherein the separator is activated alumina / g.   A non-aqueous secondary battery comprising a positive electrode, a negative electrode and a separator,
  A non-aqueous secondary battery using the non-aqueous secondary battery separator according to claim 4 or 5 as the separator.