JP2001135355A - Secondary battery - Google Patents

Abstract

PROBLEM TO BE SOLVED: To solve problems such as a low dry temperature and a low self carrying characteristic in a polymer gel secondary battery which is compact in size, high in capacity, and used for an electronic apparatus. SOLUTION: A compound obtained by reacting a compound in which substitutes including an aliphatic double bond are introduced into 6-membered cyclic compound at three points, with a polymer having poly ether as a main component of its main chain, and having aliphatic double bonds at both ends thereof is used as a structutral element of an ionic conductor. Therefore, a secondary battery having an electrolyte whose drying temperature is higher than the conventional product and which keeps self carrying characteristic, can be provided.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a secondary battery that can be used as a power source for electronic equipment.

[0002]

2. Description of the Related Art As the performance of electronic equipment has been improved, it has become necessary to make the equipment smaller and more portable. Accordingly, a small and high-capacity secondary battery has been demanded. Conventionally used secondary batteries include lead-acid batteries, nickel-cadmium batteries, and the like. Lithium-based secondary batteries having higher energy density have been attracting attention instead of these batteries.

In this lithium-based secondary battery, an attempt was initially made to use lithium metal as an active material, but dendritic metal grew on the electrode surface during repeated charging and discharging.
It has been found that there is a problem that when the growth amount becomes excessive, the battery sometimes overheats. As one method for preventing this, a carbonaceous material that can occlude lithium between layers has been used instead of metallic lithium. When a carbonaceous material is used, lithium dendrites do not grow, which is effective for suppressing overheating of the battery.

The problem of lithium dendrite growth in a lithium secondary battery has been solved as described above. However, in a conventional battery using a liquid as an electrolyte, a durable container is required to prevent leakage of the electrolyte. And a seal structure is used. There is also a problem that the weight and thickness of the battery cannot be reduced as a result of the container and the seal structure. In addition, there is a problem that an expensive or complicated device is required to seal a container having a notch or the like.

[0005] In order to solve this problem, the electrolyte is solidified or gelled so that a simpler container or seal structure can be used than when a liquid is used, and the battery can be made thinner and freely shaped. Is being done. Furthermore, due to solidification and gelation, the heat resistance such as the ignition point tends to be higher than that of the liquid, and it is expected to be advantageous in the assembly and fabrication process.

[0006] In accordance with the above idea, Japanese Patent Application Laid-Open No. 9-50048
Lithium secondary batteries obtained by gelling an electrolytic solution prepared by the method disclosed in Japanese Patent Application Laid-Open No. 5 (1993) -1993 have been put to practical use.

[0007]

As described in the prior art, the battery prepared by gelling the electrolyte prepared by the method disclosed in Japanese Patent Application Laid-Open No. 9-500485 has a high molecular weight and a low molecular weight constituting the gel. It is considered that the solvent does not show good affinity chemically and has a microscopically separated structure. For this reason, the drying temperature of the electrolyte is almost the same as that of the conventional liquid system, and there is a problem that the drying resistance is hardly improved. As a countermeasure for this, it is desired to use a polymer having a better affinity for a low molecular weight solvent for the gel matrix, but on the contrary, the gel plasticity increases and the mechanical strength decreases. .

[0008] The present invention is to solve such a problem,
An object of the present invention is to realize a secondary battery having an electrolyte that has a higher drying temperature than conventional ones and that maintains self-supporting properties.

[0009]

In order to solve the above-mentioned problems, the present invention provides a polymer having a polyether as a main component and having an aliphatic double bond at both ends thereof, A compound formed by reacting a substituent containing a three-membered cyclic compound with a compound introduced at three positions is used as a component of the ionic conductor, whereby the drying temperature is higher than conventional ones, and the self-supporting property is maintained. A secondary battery having an electrolyte can be realized.

Further, a polymer having polyether as a main component of a main chain and having alcoholic hydroxyl groups at both ends thereof is formed by reacting with a compound having a substituent having an isocyanate group introduced at three positions in a six-membered cyclic compound. The compound thus obtained is used as a component of the ion conductor, which also makes it possible to realize a secondary battery having an electrolyte that has a higher drying temperature than conventional ones and that maintains self-supporting properties.

Further, a polymer having polyether as a main component of the main chain and having amino groups at both ends thereof is produced by reacting with a compound in which a substituent having an epoxide group is introduced at three positions into a six-membered cyclic compound. The compound is used as a component of the ion conductor, and this also makes it possible to realize a secondary battery having an electrolyte that has a higher drying temperature than conventional ones and that maintains self-supporting properties.

Further, a polymer formed by reacting a polymer having polyether as a main component of the main chain and having an aliphatic double bond at both ends thereof and a polymer containing polybutadiene as a component is used as an ion conductor. As a constituent element, this also makes it possible to realize a secondary battery having an electrolyte that has a higher drying temperature than conventional ones and that maintains self-supporting properties.

[0013] By realizing the secondary battery by the means mentioned above, the drying temperature is higher than that of the conventional one, and the electrolyte has an electrolyte maintaining self-supporting property, and particularly has a thickness of 4 mm or less. Thin secondary battery can be realized.

[0014]

BEST MODE FOR CARRYING OUT THE INVENTION The invention according to claim 1 of the present invention comprises a polymer having a polyether as a main component of a main chain and having an aliphatic double bond at both ends thereof, and an aliphatic double bond. A secondary battery characterized in that a compound formed by reacting a compound obtained by introducing a substituent into a six-membered cyclic compound at three positions is used as a component of an ion conductor, This has the effect of making it possible to realize a secondary battery having an electrolyte that has a higher drying temperature than that of the battery and that maintains self-supporting properties.

The invention according to claim 2 of the present invention relates to a polymer having polyether as a main component of the main chain and having an alcoholic hydroxyl group at both terminals, and a six-membered cyclic compound having a substituent containing an isocyanate group. A secondary battery, characterized in that a compound produced by reacting with a compound introduced at three points is used as a component of an ion conductor, using this, a drying temperature is higher than conventional ones, and This has the function of realizing a secondary battery having an electrolyte that maintains self-supporting properties.

According to a third aspect of the present invention, there is provided a polymer having polyether as a main component of a main chain and having amino groups at both ends thereof and a substituent containing an epoxide group in a six-membered cyclic compound. A secondary battery, characterized in that a compound produced by reacting with a compound introduced at a site is used as a component of an ion conductor, the drying temperature being higher than that of a conventional battery, and the use of a secondary battery. It has the function of realizing a secondary battery having an electrolyte that maintains supportability.

According to a fourth aspect of the present invention, a polymer having polyether as a main component and an aliphatic double bond at both ends thereof is reacted with a polymer having polybutadiene as a component. A secondary battery characterized in that the polymer produced by the above is used as a component of an ion conductor, using the same to provide an electrolyte which has a higher drying temperature and a higher self-supporting property than conventional ones. And has the function of realizing a secondary battery.

According to a fifth aspect of the present invention, there is provided the secondary battery according to any one of the first to fourth aspects, wherein the polyether contains at least a —CH ₂ OCH ₂ — unit. Accordingly, the use of this has the effect of making it possible to realize a secondary battery having an electrolyte which has a higher drying temperature than conventional ones and which maintains self-supporting properties.

According to a sixth aspect of the present invention, there is provided the secondary battery according to any one of the first to fifth aspects, wherein the ionic conductor is a gel containing a low molecular weight solvent. By using this, it has the effect of making it possible to realize a secondary battery having an electrolyte which has a higher drying temperature than conventional ones and which maintains self-supporting properties.

According to a seventh aspect of the present invention, there is provided a secondary battery according to any one of the first to sixth aspects, wherein the ionic conductor dissolves lithium ions as a component of the electrolyte. Accordingly, the use of this has the effect of making it possible to realize a secondary battery having an electrolyte which has a higher drying temperature than conventional ones and which maintains self-supporting properties.

The invention according to claim 8 of the present invention is the secondary battery according to any one of claims 1 to 7, further comprising an electrode that functions by inserting and extracting lithium ions. By using this, it has the effect of making it possible to realize a secondary battery having an electrolyte which has a higher drying temperature than the conventional one and which maintains self-supporting properties.

According to a ninth aspect of the present invention, there is provided a secondary battery according to any one of the first to eighth aspects, wherein the thickness is 4 mm or less. This has the effect of making it possible to realize a thin secondary battery having an electrolyte which has a higher drying temperature than that of the above and has an electrolyte which maintains self-supporting properties.

[0023]

Next, specific examples of the present invention will be described.

In the following description, the present invention will be described on the basis of experimental results. However, the present invention is not limited to the following examples, but can be carried out by appropriately changing the scope without changing the gist. is there.

First, a comparative example will be described, and then an example of the present invention will be described.

Comparative Example 1 0.5 g of a copolymer of vinylidene fluoride and propylene hexafluoride and 0.3 g of dibutyl phthalate
Was dissolved in 4 g of acetone to obtain a polymer solution. Apply a polymer solution on a glass substrate using a spin coater,
To obtain a polymer film. The thickness of the polymer film is 24μ
m. Lithium tetrafluoroborate (1 mol / l) was dissolved in a solvent in which diethyl carbonate and ethylene carbonate were mixed at a ratio of 1: 1 to prepare an electrolytic solution. After the polymer film was washed with diethyl carbonate to remove dibutyl phthalate, it was immersed in an electrolytic solution to obtain a gel electrolyte. FIG. 1 shows the results of differential scanning calorimetry of the obtained gel electrolyte.

(Comparative Example 2) 10 g of polyethylene oxide having hydroxyl groups at both ends was placed in 15 g of toluene, and methacrylic acid was added to prepare a raw material liquid. The amount of added methacrylic acid was twice as large as the number ratio to the terminal hydroxyl group of polyethylene oxide. 0.2 g of toluenesulfonic acid was added to the raw material liquid to obtain a reaction stock solution. The reaction was proceeded by heating the undiluted solution under reflux. Every hour, methacrylic acid was added in an equal amount by the number ratio to the polyethylene oxide terminal hydroxyl group at the time of charging.

Finally, the total ratio of the added methacrylic acid to the polyethylene oxide terminal hydroxyl group at the time of charging was 6 times in total. Further, the reaction was continued while refluxing for 3 hours, and then allowed to cool to room temperature to obtain a reaction solution. The obtained reaction solution was neutralized by adding a saturated ethanol solution of lithium hydroxide. After neutralization, the precipitate was removed by filtration, and the filtrate was dried over magnesium sulfate for one day. The magnesium sulfate was removed by filtration, and the filtrate was dried under vacuum to obtain methacrylic acid esterified polyethylene oxide.

The methacrylic acid-esterified polyethylene oxide, the electrolytic solution of Comparative Example 1 and dimethoxyphenylacetophenone were mixed at a weight ratio of 50: 300: 1 to prepare a stock gel solution. The gel stock solution was placed in a petri dish, irradiated with ultraviolet rays for 15 minutes, and then the obtained film was rinsed in an electrolytic solution to obtain a gel electrolyte.

FIG. 2 shows the result of differential scanning calorimetry of the obtained gel electrolyte.

Example 1 To the methacrylic acid-esterified polyethylene oxide of Comparative Example 2 was added an equal amount of triallyl isocyanurate in terms of the double bond number ratio, and the electrolytic solution of Comparative Example 1 and dimethoxyphenylacetophenone were added. Was added so that the weight ratio to methacrylic acid-esterified polyethylene oxide was the same as that of Comparative Example 2 to obtain a stock gel solution. The obtained gel stock solution was treated in the same manner as in Comparative Example 2 to obtain a gel electrolyte.

FIG. 3 shows the results of differential scanning calorimetry of the obtained gel electrolyte.

Example 2 Polyethylene oxide having hydroxyl groups at both ends and the electrolyte of Comparative Example 1 were mixed at a weight ratio of 1: 6 to prepare a stock gel solution. Separately, 電解 of the electrolyte of Comparative Example 1 was taken as the electrolyte of the stock gel solution, and benzene triisocyanate was dissolved in an amount of ３ of the number ratio to the terminal hydroxyl groups of polyethylene oxide in the stock gel solution, and the curing agent was dissolved. And

The gel stock solution and the curing agent were mixed, immediately placed in a petri dish, and cured, and the resulting film was rinsed with an electrolytic solution to obtain a gel electrolyte.

FIG. 4 shows the results of differential scanning calorimetry of the obtained gel electrolyte.

(Example 3) Polyethylene oxide having both ends 3-aminopropylated and the electrolyte solution of Comparative Example 1 were mixed at a weight ratio of 1: 6 to prepare a stock gel solution. Separately, the electrolyte of Comparative Example 1 was １ ／ of the electrolyte of the gel stock solution, and triglycidyl isocyanurate was dissolved in such an amount that the epoxide group and the terminal amino group of the polyethylene oxide of the gel stock solution were equivalent, A curing agent was used.

The gel stock solution and the curing agent were mixed, immediately placed in a Petri dish, and cured, and the resulting film was rinsed with an electrolyte to obtain a gel electrolyte.

FIG. 5 shows the result of differential scanning calorimetry of the obtained gel electrolyte.

Example 4 The methacrylic acid esterified polyethylene oxide of Comparative Example 2, polybutadiene rubber, dimethoxyphenylacetophenone and the electrolyte of Comparative Example 1 were mixed at a weight ratio of 50: 5: 1: 300, respectively.
A gel stock solution was used. The obtained gel stock solution was treated in the same manner as in Comparative Example 2 to obtain a gel electrolyte.

FIG. 6 shows the results of differential scanning calorimetry of the obtained gel electrolyte.

Example 5 A mixture of 10% poly (vinylidene fluoride) dissolved in N-methylpyrrolidone and lithium cobalt oxide powder were mixed and applied on an aluminum foil having a thickness of 20 μm. Preliminary drying was performed for 15 minutes, and then vacuum drying was performed at 70 ° C. for 2 hours to produce a positive electrode. In addition,
The polyvinylidene fluoride was adjusted to 10% by dry weight based on lithium cobaltate.

A mixture of 10% poly (vinylidene fluoride) dissolved in N-methylpyrrolidone and graphite powder was kneaded, applied to a copper foil, and preliminarily dried at 65 ° C. for 15 minutes.
Vacuum drying was performed at 0 ° C. for 2 hours to obtain a negative electrode. Incidentally, polyvinylidene fluoride was adjusted to be 10% by dry weight with respect to graphite.

The obtained cathode and anode were immersed in the electrolyte of Comparative Example 1 for 10 hours to obtain a cathode and an anode containing the electrolyte.

The gel electrolytes obtained in Examples 1 to 4 and Comparative Examples 1 and 2 were sandwiched between a positive electrode and a negative electrode containing an electrolytic solution, respectively, and wrapped with a folded aluminum foil polyolefin laminate film. Sealed by vacuum heat fusion. In addition, conductive leads were respectively drawn out of the positive electrode and the negative electrode.

The maximum thickness of the obtained battery is 0.47 m
m. The charge / discharge capacity of the obtained battery was as shown in (Table 1).

[0046]

[Table 1]

As described above, when Examples 1 to 4 are compared with Comparative Example 1, it can be seen that the gel electrolyte of each Example is difficult to dry to a higher temperature. Examples 1 to 4 and Comparative Examples 1 and 2
It can also be seen that the gel electrolyte of each example is hardly dissolved. Further, according to Example 5, it can be seen that the discharge capacity was the same as that using the gel electrolytes of Comparative Examples 1 and 2 even when the gel electrolytes of Examples 1 to 4 were used.

The salt dissolved in the gel electrolyte is not limited to the tetrafluoroborate used in each embodiment.
It is also possible to change to other salts such as hexafluorophosphate, various amide salts, imide salts and perchlorates. Further, it is possible to use not only one kind of salt but also a mixture of plural kinds of salts.

As the solvent for swelling the gel electrolyte, a mixed solvent of ethylene carbonate and diethyl carbonate is used. However, it is possible to change the solvent to another solvent as long as a side reaction such as a decomposition reaction does not occur.

In the batteries of the examples, lithium cobaltate and graphite were used as electrodes capable of inserting and extracting lithium. Instead of these, for example, lithium nickelate, lithium manganese oxide, lithium vanadium oxide and the like were used. Can be used. It is also possible to use other compounds capable of inserting and extracting lithium.

In the embodiment, the aluminum foil polyolefin laminate film is used as the case, but the material of the case can be replaced with metal, synthetic resin or the like. The shape of the case may be a plate, a column, a circle, a square, or the like, or any other shape having a notch.

Further, in the embodiment, the positive electrode and the negative electrode are laminated one by one, but it is also possible to laminate a plurality of each.
It is also possible to wind. The effect of the present invention does not depend on the order of lamination, single-sided / double-sided coating, and the number of positive and negative electrodes.

[0053]

As described above, according to the present invention, a polymer having a polyether as the main component of the main chain and having an aliphatic double bond at both terminals is substituted with a substituent having an aliphatic double bond by six. A compound formed by reacting with a compound introduced into the three-membered cyclic compound at three positions is used as a component of the ion conductor, whereby
A secondary battery having an electrolyte that has a higher drying temperature than conventional ones and that maintains self-supporting properties can be realized.

Further, a polymer having polyether as a main component of the main chain and having alcoholic hydroxyl groups at both ends thereof is reacted with a compound having three substituents having isocyanate groups introduced into a six-membered cyclic compound. The compound thus obtained is used as a component of the ion conductor, which also makes it possible to realize a secondary battery having an electrolyte that has a higher drying temperature than conventional ones and that maintains self-supporting properties.

Furthermore, a polymer having polyether as a main component of the main chain and having amino groups at both ends thereof was produced by reacting with a compound in which a substituent having an epoxide group was introduced at three places into a six-membered cyclic compound. The compound is used as a component of the ion conductor, and this also makes it possible to realize a secondary battery having an electrolyte that has a higher drying temperature than conventional ones and that maintains self-supporting properties.

Further, a polymer formed by reacting a polymer having a polyether as a main component of the main chain and having an aliphatic double bond at both ends thereof and a polymer containing polybutadiene as a component is used as an ion conductor. As a constituent element, this also makes it possible to realize a secondary battery having an electrolyte that has a higher drying temperature than conventional ones and that maintains self-supporting properties.

By realizing the secondary battery by the above-mentioned means, it is characterized in that the drying temperature is higher than that of the conventional one, and that the electrolyte has an electrolyte that maintains its self-supporting property, and in particular, has a thickness of 4 mm or less. Thin secondary battery can be realized.

[Brief description of the drawings]

FIG. 1 is a diagram showing the results of differential scanning calorimetry of Comparative Example 1.

FIG. 2 is a diagram showing the results of differential scanning calorimetry of Comparative Example 2.

FIG. 3 is a diagram showing the results of differential scanning calorimetry of the first embodiment of the present invention.

FIG. 4 is a diagram showing the results of differential scanning calorimetry of the second embodiment of the present invention.

FIG. 5 is a diagram showing the results of differential scanning calorimetry of the third embodiment of the present invention.

FIG. 6 is a diagram showing the results of differential scanning calorimetry of the fourth embodiment of the present invention.

Continued on the front page F term (reference) 4J027 AA03 AC03 AC06 AJ08 BA29 CA14 CA33 CD00 4J034 DA01 DB04 DB07 DG03 HA01 HA08 HC12 HC61 HC71 MA01 RA14 5H029 AJ00 AJ03 AJ11 AK03 AL07 AM02 AM07 AM11 BJ02 BJ04 HJ02 HJ04

Claims (9)

[Claims] 1. A polymer in which a polyether is a main component of a main chain and an aliphatic double bond is provided at both ends thereof, and a compound obtained by introducing a substituent containing an aliphatic double bond into a six-membered cyclic compound at three positions. And a compound formed by reacting the above with a compound as a component of an ion conductor. 2. A polymer having a main chain of polyether as a main component and having alcoholic hydroxyl groups at both ends thereof, and a compound obtained by introducing a substituent containing an isocyanate group into a six-membered cyclic compound at three positions. A secondary battery comprising the produced compound as a component of an ion conductor. 3. A polymer formed by reacting a polymer having polyether as a main component of the main chain and having amino groups at both ends thereof, and a compound having a substituent containing an epoxide group introduced at three positions into a six-membered cyclic compound. A secondary battery comprising the compound obtained as a component of an ion conductor. 4. A polymer formed by reacting a polymer having a polyether as a main component of a main chain and having an aliphatic double bond at both ends with a polymer containing a polybutadiene as a component, A secondary battery, which is a constituent element. 5. The method of claim 5, wherein the polyether is at least —CH ₂ OCH ₂ —
The secondary battery according to any one of claims 1 to 4, comprising a unit. 6. The secondary battery according to claim 1, wherein the ionic conductor is a gel containing a low molecular weight solvent. 7. The ion conductor according to claim 1, wherein lithium ion is dissolved as a component of the electrolyte.
7. The secondary battery according to any one of items 6 to 6. 8. The secondary battery according to claim 1, further comprising an electrode that functions by inserting and extracting lithium ions. 9. The secondary battery according to claim 1, wherein the thickness is 4 mm or less.