Polymer solid electrolyte and lithium secondary cell adopting the same

Claim 2

A polymer solid electrolyte comprising: a polymer matrix composed of a copolymer of a polymerizable monomer represented by the formula (1) and a cross-linking agent represented by the formula (2); a polymerization initiator; and an electrolyte solution containing an inorganic salt and a solvent, ##STR2## where R 1 is selected from hydrogen or a methyl group, R 2 and R 3 each are independently selected from the group consisting of hydrogen, C 1 ˜C 6 alkyl, --(R)N(R') 2 and --(R")OH, R 4 and R 5 each are independently selected from hydrogen or methyl, n is an integer between 3 and 30, and wherein R, R' and R" each are a C1˜C 6 alkyl group.

Claim 3

A polymer solid electrolyte as claimed in claim 1, wherein the polymerizable monomer represented by the formula (1) and the cross-linking agent represented by the formula (2) are mixed together in a mixing ratio within the range of from 1:9˜9:1, based on weight.

Claim 4

A polymer solid electrolyte as claimed in claim 1, wherein the polymerizable monomer represented by the formula (1) is at least one selected from the group consisting of acryl amide, N,N-dimethylacryl amide, N,N-diethylacryl amide, N-isopropylacryl amide, N,N-dimethylaminopropylacryl amide, and acryloyl morpholine.

Claim 5

A polymer solid electrolyte as claimed in claim 1, wherein the cross-linking agent represented by formula (2) is selected from polyethyleneglycol diacrylate or polyethyleneglycol dimethacrylate.

Claim 6

A polymer solid electrolyte as claimed in claim 1, wherein the solvent is a non-aqueous solvent having a high dielectric constant.

Claim 7

A polymer solid electrolyte as claimed in claim 1, wherein the solvent is a mixture of a non-aqueous solvent with a high dielectric constant and a solvent having an amide group.

Claim 8

A polymer solid electrolyte as claimed in claim 5, wherein the non-aqueous solvent is at least one selected from the group consisting of propylene carbonate, ethylene carbonate, γ-butyrolacetone, 1,3-dioxolane, dimethoxyethane, dimethylcarbonate, diethylcarbonate, tetrahydrofuran (THF), dimethylsulfoxide and polyethyleneglycol dimethylether.

Claim 9

A polymer solid electrolyte as claimed in claim 6, wherein the solvent having the amide group is at least one selected from the group consisting of N,N-dimethylacetamide, N,N-diethylacetamide, N,N-dimethylformamide and N,N-diethylformamide.

Claim 10

A polymer solid electrolyte as claimed in claim 6, wherein the mixing ratio of the non-aqueous solvent and the solvent having the amide group is 1:3 ˜3:1 based on volume.

Claim 11

A polymer solid electrolyte as claimed in claim 6, wherein the mixing ratio of the non-aqueous solvent and the solvent having the amide group is 1:1 based on volume.

Claim 12

A polymer solid electrolyte as claimed in claim 1, wherein the inorganic salt is at least one selected from the group consisting of lithium perchlorate (LiClO 4 ), lithium tetrafluoroborate (LiBF 4 ), lithium hexafluorophosphate (LiPF 6 ), lithium trifluoromethansulfonate (LiCF 3 SO 3 ) and lithium bistrifluoromethansulfonylamide (LiN(CF 3 SO 2 ) 2 ).

Claim 13

A polymer solid electrolyte as claimed in claim 1, wherein the content of the polymerizable monomer represented by formula (1) is within the range of from 10˜15 wt %, based on the weight of the polymer solid electrolyte.

Claim 14

A polymer solid electrolyte as claimed in claim 1, wherein the content of the cross-linking agent represented by formula (2) is within the range of from 5˜15 wt %, based on the weight of the polymer solid electrolyte.

Claim 15

A polymer solid electrolyte as claimed in claim 1, wherein the content of the polymerization initiator is within the range of from 0.5˜1.5 wt %, based on the weight of the polymer solid electrolyte.

Claim 16

A polymer solid electrolyte as claimed in claim 1, wherein the content of the electrolyte solution is within the range of from 68.5˜84.5 wt %, based on the weight of the polymer solid electrolyte.

Claim 17

A polymer solid electrolyte as claimed in claim 1, wherein the content of the inorganic salt is within the range of from 6˜17 wt % based on the weight of the electrolyte solution.

Claim 18

A lithium secondary cell comprising the polymer solid electrolyte as claimed in claim 1.

Claim 21

The method as claimed in claim 18, wherein the polymerizable monomer represented by the formula (1) and the cross-linking agent represented by the formula (2) are mixed together in a mixing ratio within the range of from 1:9˜9:1, based on weight.

Claim 22

A method of making a lithium secondary cell comprising: mixing the polymer solid electrolyte as claimed in claim 1 with (i) an active material for use as a lithium cathode and (ii) a conductive agent; coating this mixture on a cathode current collector; heating to form a composite cathode layer; mixing carbon powder and the polymer solid electrolyte on an anode current collector; heating to form a composite anode layer; forming a polymer solid electrolyte layer by coating the polymer solid electrolyte on a thin film and completing polymerization; and placing the polymer solid electrolyte layer between the composite anode layer and the composite cathode layer.

Claim 23

A secondary cell, comprising: a cathode; an anode; and a first solid polymer electrolyte between the anode and the cathode; wherein at least one of the anode and the cathode comprises an active material and the first solid polymer electrolyte.

Claim 24

A secondary cell, comprising: a cathode; an anode; and a first solid polymer electrolyte between the anode and the cathode; wherein at least one of the anode and the cathode comprises an active material and the first solid polymer electrolyte.

Claim 25

A secondary cell of claim 21, wherein: the cathode comprises a cathode current collector, the first solid polymer electrolyte, and a cathode active material selected from lithium manganese oxide, lithium nickel oxide or lithium cobalt oxide; the anode comprises an anode current collector, the first solid polymer electrolyte, and an anode active material selected from lithium, lithium alloy or carbon; and the first solid polymer electrolyte comprises a polymerization initiator; an electrolyte solution containing an inorganic salt and a solvent; and a polymer electrolyte medium having a polymer matrix comprised of a copolymer of a polymerizable monomer expressed by the formula (1) and a cross-linking agent expressed by the formula (2); ##STR4## where R 1 is hydrogen or a methyl group, and R 2 and R 3 are each independently one selected from the group consisting of hydrogen, methyl, ethyl, propyl, dialkylaminopropyl (--C 3 H 6 N(R') 2 ) and hydroxyethyl (CH 2 CH 2 OH) groups, and R 4 and R 5 are each independently hydrogen or a methyl group, and n is an integer from 3 to 30, wherein R' is a C 1 ˜C 5 alkyl group.