Polymer electrolyte

• US 20030082458A1
• Filed: 08/26/2002
• Published: 05/01/2003
• Est. Priority Date: 03/17/1999
• Status: Active Grant

• Current Assignee: Noboru Oyama
• Original Assignee: Noboru Oyama
• Inventors: Oyama, Noboru
• Granted Patent: US 7,105,254 B2
• Time in Patent Office: Days
• US Class Current: 429/303
• CPC Class Codes: C08F 290/062 Polyethers
• CPC Class Codes: C08G 65/3322 acyclic
• CPC Class Codes: C08L 2666/04 Macromolecular compounds according to groups C08L7/00 - C08L49/00, or C08L55/00 - C08L57/00; Derivatives thereof
• CPC Class Codes: C08L 71/02 Polyalkylene oxides
• CPC Class Codes: H01M 10/052 Li-accumulators
• CPC Class Codes: H01M 10/0565 Polymeric materials, e.g. gel-type or solid-type
• CPC Class Codes: H01M 10/0569 characterised by the solvents
• CPC Class Codes: H01M 2300/0085 Immobilising or gelification of electrolyte
• CPC Class Codes: H01M 6/164 by the solvent
• CPC Class Codes: H01M 6/22 Immobilising of electrolyte
• CPC Class Codes: Y02E 60/10 Energy storage using batteries

Abstract

A polymer electrolyte providing lithium secondary batteries in which growth of lithium dendrites is suppressed and batteries exhibiting excellent discharge characteristics in low to high temperature, comprising a polymer gel holding a nonaqueous solvent containing an electrolyte, wherein the polymer gel comprises (I) a unit derived from at least one monomer having one copolymerizable vinyl group and (II) a unit derived from at least one compound selected from the group consisting of (II-a) a compound having two acryloyl groups and a (poly)oxyethylene group, (II-b) a compound having one acryloyl group and a (poly)oxyethylene group, and (II-c) a glycidyl ether compound, particularly the polymer gel comprises monomer (I), compound (II-a), and a copolymerizable plasticizing compound.

Claims

1. A polymer electrolyte comprising:

a polymer gel holding a nonaqueous solvent containing an electrolyte, wherein said polymer gel comprises (I) a unit derived from at least one monomer having one copolymerizable vinyl group and (II) a unit derived from at least one compound selected from the group consisting of (II-a) a compound having two acryloyl groups and a (poly)oxyethylene group, (II-b) a compound having one acryloyl group and a (poly)oxyethylene group, and (II-c) a glycidyl ether compound.

2. The polymer electrolyte according to claim 1, wherein said at least one monomer providing unit (I) is at least one monomer selected from the group consisting of (meth)acrylonitrile, an (α

-alkyl)acrylic acid, an alkyl(α

-alkyl)acrylate, a fluoroalkyl(α

-alkyl)acrylate, a fluoroalkyl(α

-fluoroalkyl)acrylate, a vinyl ester, a vinylalkyl ether, an allylalkyl ether, an allyl ester, vinyl alcohol, vinyl chloride, vinylidene chloride, and a cyclic olefin.

3. The polymer electrolyte according to claim 1, wherein said compound (II-a) is represented by one of formulae (1) and (2):

H₂C═

C(R)COO(CH₂CH₂O)_n—

COC(R)═

CH₂  

 

(1)

wherein n represents an integer 1 to 23;

R represents an alkyl group having 1 to 4 carbon atoms.

H₂C═

C(R)COO[(CH₂CH₂O)_p—

(CH₂CH(R¹)O_q—

(X)_r—

(CH₂CH₂O)_p]COC(R)═

CH₂ 

 

(2)

wherein R represents an alkyl group having 1 to 4 carbon atoms;

R¹ represents a hydrogen atom or a methyl group;

X represents a bisphenol group;

p represents an integer of 16 or smaller;

q represents an integer of 34 or smaller; and

r represents 0 or 1.

4. The polymer electrolyte according to claim 1, wherein said compound (II-b) is at least one compound selected from a compound represented by formula (3):

H₂C═

C(R)COO(CH₂CH(R¹)O)_s—

R² 

 

(3)

wherein R represents a hydrogen atom or an alkyl group having 1 to 4 carbon atoms;

R¹ and R² each represent a hydrogen atom or a methyl group; and

s represents an integer of 1 to 100, a compound represented by formula (4);

H₂C═

CHCH₂O—

(CH₂CH₂O)_x—

(CH₂CH(R¹)O)_y—

R³ 

 

(4)

wherein R¹ represents a hydrogen atom or a methyl group;

R³ represents a hydrogen atom or an alkyl group; and

x and y represent mole percents totaling 100%, wherein x=100% and y=0%, or x≦

50% and y≧

50%,

and a compound represented by formula (5);

H₂C═

CHCOO(CH₂CH₂O)_x—

(CH₂CH(R¹)O)_y—

R² 

 

(5)

wherein R¹ and R² each represent a hydrogen atom or a methyl group; and

x and y represent mole percents totaling 100%, wherein x=0% and y=100%, or x≧

50% and y≦

50%.

5. The polymer electrolyte according to claim 1, wherein said compound (II-a) and said compound (II-b) have a weight average molecular weight of 5000 or less.

13. The polymer electrolyte according to claim 1, wherein said electrolyte contains at least one lithium salt selected from the group consisting of CF₃SO₃Li, C₄F₉SO₃Li, (CF₃SO₂)₂NLi, (CF₃SO₂)₃CLi, LiBF₄, LiPF₆, LiClO₄, and LiAsF₆.

15. The polymer electrolyte according to claim 13, wherein said nonaqueous solvent comprises at least one compound selected from the group consisting of a cyclic carbonate, an acyclic carbonates, a cyclic ester, an amide compound, and a nitrile compound.

16. The polymer electrolyte according to claim 1, wherein said electrolyte contains at least one salt selected from the group consisting of CF₃SO₃Li, C₄F₉SO₃Li, (CF₃SO₂)₂NLi, (CF₃SO₂)₃CLi, LiBF₄, LiPF₆, LiClO₄, LiAsF₆, these salts with the lithium ion displaced with other alkali metals, a tetraalkylammonium salt, a tetraalkylfluoroborate, a tetraalkylphosphonium fluoroborate, a tetraalkylphosphonium trifluorosulfonate, an alkylpyridinium salt, and an N-alkylimidazole salt.

18. The polymer electrolyte according to claim 15, wherein said nonaqueous solvent contains an organic solvent having a donor number of 0.1 or greater and a dielectric constant of 10.0 or greater.

19. The polymer electrolyte according to claim 18, wherein said organic solvent comprises at least one compound selected from the group consisting of a cyclic carbonate, an acyclic carbonates, a cyclic ester, a nitrile compound, an acid anhydride, an amide compound, a phosphate compound, and an amine compound.

6. A polymer electrolyte comprising a polymer gel holding a nonaqueous solvent containing an electrolyte, wherein said polymer gel comprises (A) a unit derived from at least one monomer having one copolymerizable vinyl group, (B) a unit derived from a compound having two acryloyl groups and a (poly)oxyethylene group, and (C) a unit derived from a plasticizing compound having a polymerizable group.

7. The polymer electrolyte according to claim 6, wherein said at least one monomer providing unit (A) is at least one monomer selected from the group consisting of (meth)acrylonitrile, an (α

-alkyl)acrylic acid, an alkyl(α

-alkyl)acrylate, a fluoroalkyl(α

-alkyl)acrylate, a fluoroalkyl(α

-fluoroalkyl)acrylate, a vinyl ester, a vinylalkyl ether, an allylalkyl ether, an allyl ester, vinyl alcohol, vinyl chloride, vinylidene chloride, and a cyclic olefin.

8. The polymer electrolyte according to claim 6, wherein said compound providing unit (B) is represented by one of formulae (1) and (2):

H₂C═

C(R)COO(CH₂CH₂O)_n—

COC(R)═

CH₂ 

 

(1)

wherein n represents an integer 1 to 23;

R represents an alkyl group having 1 to 4 carbon atoms.

H₂C═

C(R)COO[(CH₂CH₂O)_p—

(CH₂CH(R¹)O_q—

(X)<sub>r—

(CH2</sub>CH₂O)_p]COC(R)═

CH₂ 

 

(2)

wherein R represents an alkyl group having 1 to 4 carbon atoms;

R¹ represents a hydrogen atom or a methyl group;

X represents a bisphenol group;

p represents an integer of 16 or smaller;

q represents an integer of 34 or smaller; and

r represents 0 or 1.

9. The polymer electrolyte according to claim 6, wherein said plasticizing compound providing unit (C) has a solidification point of 60°

C. or lower.

10. The polymer electrolyte according to claim 8, wherein said plasticizing compound providing unit (C) is at least one compound selected from a compound represented by formula (3):

H₂C═

C(R)COO(CH₂CH(R¹)O)_s—

R² 

 

(3)

wherein R represents a hydrogen atom or an alkyl group having 1 to 4 carbon atoms;

R¹ and R² each represent a hydrogen atom or a methyl group; and

s represents an integer of 1 to 100, a compound represented by formula (4);

H₂C═

CHCH₂O—

(CH₂CH₂O)_x—

(CH₂CH(R¹)O)_y—

R³ 

 

(4)

wherein R¹ represents a hydrogen atom or a methyl group;

R³ represents a hydrogen atom or an alkyl group; and

x and y represent mole percents totaling 100%, wherein x=100% and y=0%, or x≦

50% and y≧

50%,

and a compound represented by formula (5);

H₂C═

CHCOO(CH₂CH₂O)_x—

(CH₂CH(R¹)O)_y—

R² 

 

(5)

wherein R¹ and R² each represent a hydrogen atom or a methyl group; and

x and y represent mole percents totaling 100%, wherein x=0% and y=100%, or x≧

50% and y≦

50%.

11. The polymer electrolyte according to claim 6, wherein said compound providing unit (B) and said plasticizing compound providing unit (C) have a weight average molecular weight of 5000 or less.

12. The polymer electrolyte according to claim 9, wherein said compound providing unit (C) is benzylmethacrylate, isobornyl-methacrylate, diethylaminoethylbenzylmethacrylate chloride, diethylaminoethyl-methacrylate, dimethylaminoethylmethyl-methacrylate chloride, trifluoroethylmethacrylate, cyclohexyl-methacrylate, 2-methacryloyloxyethylphthalate, 2-methacryloyloxyethylhexahydrophthalate, butylepoxystearate, and dioctylepoxyhexahydrophthalate.

14. The polymer electrolyte according to claim 6, wherein said electrolyte contains at least one lithium salt selected from the group consisting of CF₃SO₃Li, C₄F₉SO₃Li, (CF₃SO₂)₂NLi, (CF₃SO₂)₃CLi, LiBF₄, LiPF₆, LiClO₄, and LiAsF₆.

17. The polymer electrolyte according to claim 6, wherein said electrolyte contains at least one salt selected from the group consisting of CF₃SO₃Li, C₄F₉SO₃Li, (CF₃SO₂)₂NLi, (CF₃SO₂)₃CLi, LIBF₄, LiPF₆, LiClO₄, LiAsF₆, these salts with the lithium ion displaced with other alkali metals, a tetraalkylammonium salt, a tetraalkylfluoroborate, a tetraalkylphosphonium fluoroborate, a tetraalkylphosphonium trifluorosulfonate, an alkylpyridinium salt, and an N-alkylimidazole salt.