Polyelectrolytic gel

Details Polyelectrolytic gel Polyelectrolytic gel

2000-05-17

2002-07-16

Weiner, Laura (Department: 1745)

Chemistry: electrical current producing apparatus, product, and

Current producing cell, elements, subcombinations and...

Include electrolyte chemically specified and method

C429S314000, C429S322000, C429S309000, C252S062200

Reexamination Certificate

active

06420072

ABSTRACT:

The present invention relates to a novel polyelectrolytic gel.
In secondary lithium batteries, condensers, capacitors, sensors or like devices using an electrolyte, the electrolyte should be tightly enclosed therein to prevent a liquid leakage or a fire due to short circuits, and it should be firmly encased therein to avoid an accident due to an impact. In view of this necessity, lightweight devices have been difficult to produce. For overcoming this drawback, it is desired to solidify an electrolyte.
For solidification of electrolytes, solid electrolytes and polyelectrolytic gels have been proposed which are applicable to electrochemical devices such as secondary batteries, condensers, capacitors, sensors or the like. For example, the proposals include solid electrolytes which comprise a mixture of an electroconductive powder with polyacrylonitrile or an acrylonitrile/methyl (meth)acrylate non-crosslinked copolymer (Electrochimica. Act., Vol.37, No.10, 1851-1854, 1992, JP-A-4-306560 and JP-A-7-45271); and polyelectrolytic gels produced by using a crosslinked polymer formed from polyethylene glycol diacrylate, polyethylene glycol dimethacrylate or the like (JP-A-62-285954 and JP-A-6-68906).
However, these solid electrolytes and electrolytic gels have drawbacks that they are low in heat resistance and that when heated to 60° C. or higher, the gel becomes structurally collapsed and unsuitable for use at a high temperature.
For improvement of heat resistance, JP-A-10-144137 proposed a polyelectrolytic gel prepared by cooling a polymer solution to a low temperature below 0° C., e.g. −20° C. to cause gelation, the polymer solution containing a non-crosslinked copolymer of acrylonitrile and methyl (meth)acrylate or vinyl acetate dissolved in a nonaqueous solvent containing an electrolyte. However, the obtained gel is instable in electroconductivity, particularly ion conductivity. When the gel is used for secondary lithium-ion batteries or electrolytic condensers, the devices not only become instable in ion conductivity immediately after production, but also increase the resistance due to repeated charge and discharge, resulting in rapid reduction of ion conductivity.
Since acrylonitrile polymers or the like used for conventional electrolytic gels or solid electrolytes are mostly produced by copolymerizing monomers having carboxyl group or sulfonic acid group, the gels and solids are likely to contain a large amount of alkali metal cations or alkaline earth metal cations or anions of sulfuric acid, nitric acid or like acids as counter ions.
For example, when an electrolytic gel using an acrylonitrile polymer contains 500 ppm or more of alkali metal ions or alkaline earth metal ions other than lithium ions, lithium ions are low in mobility, i.e. ion conductivity and also become lower in ion conductivity by repeated charge and discharge, so that the resulting secondary lithium-ion battery is given a short service life and is unsuitable for use.
Stated more specifically, cations or anions larger in ionic radius than lithium ions not only reduce the mobility of lithium ions in the polyelectrolytic gel but also degrade the properties of electrode materials and electrolytes by repeated charge and discharge, thereby gradually lowering the electroconductivity and shortening the service life of batteries or condensers.
It is an object of the present invention to provide a novel polyelectrolytic gel which is excellent in heat resistance and durability and is superior in electroconductivity, particularly ion conductivity.
Other objects and features of the present invention will become more apparent from the following description.
The present inventor conducted extensive research and found that the foregoing object can be achieved by a polyelectrolytic gel wherein a polymer component is swollen with a nonaqueous solvent containing an electrolyte dissolved therein, the polymer component having nitrogen-containing cationic functional group and possessing a crosslinking structure. The present invention was completed based on this novel finding.
According to the present invention, there are provided the following polyelectrolytic gels.
1. A polyelectrolytic gel comprising a polymer component and a nonaqueous solvent, characterized in that the polymer component is a crosslinked polymer having nitrogen-containing cationic functional group or a mixture of a non-crosslinked polymer having nitrogen-containing cationic functional group and a crosslinked polymer free of nitrogen-containing cationic functional group, the polymer component being swollen with the nonaqueous solvent containing an electrolyte dissolved therein.
2. The polyelectrolytic gel according to item 1, wherein the nitrogen-containing cationic functional group is at least one species selected from the class consisting of free primary amino group, secondary amino group or tertiary amino group, primary ammonium base, secondary ammonium base, tertiary ammonium base or quaternary ammonium base which ammonium bases have formed a salt with carboxy anion, and quaternary ammonium base having formed a salt with hydroxy anion.
3. The polyelectrolytic gel according to item 1, wherein the polymer component is a crosslinked polymer having nitrogen-containing cationic functional group.
4. The polyelectrolytic gel according to item 3, wherein the crosslinked polymer having nitrogen-containing cationic functional group is obtained by polymerizing and crosslinking 100 parts by weight of an unsaturated monomer free of nitrogen-containing cationic functional group, 1 to 100 parts by weight of an unsaturated monomer having nitrogen-containing cationic functional group and 1 to 50 parts by weight of a crosslinkable monomer having at least two reactive functional groups per molecule.
5. The polyelectrolytic gel according to item 4, wherein the unsaturated monomer free of nitrogen-containing cationic functional group is acrylonitrile.
6. The polyelectrolytic gel according to item 4, wherein the crosslinkable monomer has at least two reactive functional groups selected from the class consisting of hydroxyl, carboxyl, glycidyl, vinyl, isocyanate and methylol.
7. The polyelectrolytic gel according to item 3, wherein the crosslinked polymer having nitrogen-containing cationic functional group is obtained by polymerizing 100 parts by weight of an unsaturated monomer free of nitrogen-containing cationic functional group and 1 to 100 parts by weight of an unsaturated monomer having nitrogen-containing cationic functional group to give a non-crosslinked polymer, and crosslinking the resulting non-crosslinked polymer with 1 to 200 parts by weight of a crosslinking agent.
8. The polyelectrolytic gel according to item 7, wherein the non-crosslinked polymer has at least one species of reactive functional group selected from the class consisting of hydroxyl, carboxyl, glycidyl, vinyl, isocyanate and methylol, and wherein the crosslinking agent is a compound having at least one species of reactive functional group selected from the class consisting of hydroxyl, carboxyl, glycidyl, vinyl, isocyanate and methylol, the functional group of the crosslinking agent being complementarily reactive to the reactive functional group of the non-crosslinked polymer and being at least two in number per molecule.
9. The polyelectrolytic gel according to item 7, wherein the unsaturated monomer free of nitrogen-containing cationic functional group comprises acrylonitrile and the unsaturated monomer having at least one species of reactive functional group selected from the class consisting of hydroxyl, carboxyl, glycidyl and methylol.
10. The polyelectrolytic gel according to item 1, wherein the polymer component is a mixture of a non-crosslinked polymer having nitrogen-containing cationic functional group and a crosslinked polymer free of nitrogen-containing cationic functional group.
11. The polyelectrolytic gel according to item 10, wherein the non-crosslinked polymer having nitrogen-containing cationic functional group is obtained by polymerizing 100 parts by weight of an unsaturate

Affiliated with

Also associated with

Rating

Polyelectrolytic gel does not yet have a rating. At this time, there are no reviews or comments for this patent.

If you have personal experience with Polyelectrolytic gel, we encourage you to share that experience with our LandOfFree.com community. Your opinion is very important and Polyelectrolytic gel will most certainly appreciate the feedback.

Rate now

Comments { 0 }

Profile ID: LFUS-PAI-O-2903244