Mass-transport separator for alkaline nickel-zinc cells and cell

Claim 2

A mass-transport separator for fully vented alkaline nickelzinc cells comprising (1) a barrier layer comprising a microporous polyolifin membrane which is coated with a layer of from 50 A to 1000 A of a low hydrogen overpotential material having a hydrogen overpotential in alkaline solution lower than that of zinc; (2) two protective layers comprising microporous polyolifin membranes; the barrier layer being sandwiched between and in contact with the two protective layers.

Claim 3

A mass-transport separator according to claim 1 wherein the coating of low hydrogen overpotential material is from 100 A to 500 A thick.

Claim 4

A mass-transport separator according to claim 1 wherein the barrier layer of microporous polyolifin of the separator is coated on each of the two faces with a coating of the low hydrogen overpotential material which is from 50 A to 1000 A thick.

Claim 5

A mass-transport separator according to claim 3 wherein each of the coatings of low hydrogen overpotential material are from 100 A to 500 A thick.

Claim 6

A mass-transport separator according to claim 1 wherein the barrier layer of microporous polyolifin is formed by coating each of two microporous polyolifin membranes on one face with a coating of low hydrogen overpotential material which is from 50 A to 1000 A thick and then placing the two membranes together with the coated faces face to face.

Claim 7

A mass-transport separator according to claim 5 wherein the coatings of low hydrogen overpotential material are from 100 A to 500 A thick.

Claim 8

A mass-transport separator according to claim 1 wherein the barrier layer of microporous polyolifin is formed by binding a polyolifin felt to a microporous polyolifin membrane and then coating the polyolifin felt side with a coating of low hydrogen overpotential material which is from 50 A to 1000 A thick.

Claim 9

A mass-transport separator according to claim 7 wherein the coating of low hydrogen overpotential material is from 100 A to 500 A thick.

Claim 10

A mass-transport separator according to claim 1, 2, 3, 4, 5, 6, 7, or 8 wherein the low hydrogen overpotential material is nickel.

Claim 11

A mass-transport separator according to claim 1, 2, 3, 4, 5, 6, 7, or 8 wherein the low hydrogen overpotential material is stainless steel.

Claim 12

A mass-transport separator according to claim 1, 2, 3, 4, 5, 6, 7, or 8 wherein the average pore sizes of the microporous polyolifins are from 100 A to 500 A.

Claim 13

A mass-transport separator for use in alkaline nickel-zinc cells comprising: (1) a barrier layer comprising: (a) a microporous polyolifin membrane which is coated with a layer of from 50 A to 1000 A of a low hydrogen overpotential material having a hydrogen overpotential in alkaline solution lower than that of zinc, and (b) a semipermeable active layer of a hydroxyl-containing polymer covering the layer of low hydrogen overpotential material; (2) two protective layers comprising microporous polyolifin membranes; the barrier layer being sandwiched between the two protective layers.

Claim 14

A mass-transport separator for use in alkaline nickel-zinc cells comprising: (1) a barrier layer comprising: (a) a microporous polyolifin membrane which is coated with a layer of from 50 A to 1000 A of a low hydrogen overpotential material having a hydrogen overpotential in alkaline solution lower than that of zinc, and (b) a semipermeable active layer of a hydroxyl-containing polymer covering the layer of low hydrogen overpotential material; (2) two protective layers comprising microporous polyolifin membranes; the barrier layer being sandwiched between the two protective layers.

Claim 15

A mass-transport separator according to claim 12 wherein the coating of low hydrogen overpotential material is from 100 A to 500 A thick.

Claim 16

A mass-transport separator according to claim 12 or 13 wherein the low hydrogen overpotential material is nickel.

Claim 17

A mass-transport separator according to claim 12 or 13 wherein the low hydrogen overpotential material is stainless steel.

Claim 18

A mass-transport separator according to claim 12 or 13 wherein the average pore sizes of the microporous polyolifins are from 100 A to 500 A.

Claim 19

A mass-transport separator according to claim 12 or 13 wherein the semipermeable active layer of hydroxyl-containing polymer has an average pore size of from 10 A to 50 A.

Claim 20

A mass-transport separator according to claim 12 or 13 wherein the semipermeable active layer of a hydroxyl-containing polymer has an average pore size of from 15 A to 25 A.

Claim 21

A sealed alkaline nickel-zinc cell which comprises: A. a nickel-nickel hydroxide cathode; B. a zinc-zinc oxide anode; C. a mass-transport separator comprising: (1) a barrier layer comprising: (a) a microporous polyolifin membrane which is coated with a layer of from 50 A to 1000 A of low hydrogen overpotential material having a hydrogen overpotential in alkaline solution lower than that of zinc, and (b) a semipermeable active layer of hydroxyl-containing polymer covering the layer of low hydrogen overpotential material; (2) two protective layers comprising microporous polyolifin membranes, the barrier layer being sandwiched between the two protective layers; D. an alkaline electrolyte; E. means for terminating the charging of the cell when the internal gas pressure of the cell reaches a preselected value; and F. means for venting the cell if the internal gas pressure reaches a preselected value above that at which the charging of the cell is terminated.

Claim 22

A sealed alkaline nickel-zinc cell which comprises: A. a nickel-nickel hydroxide cathode; B. a zinc-zinc oxide anode; C. a mass-transport separator comprising: (1) a barrier layer comprising: (a) a microporous polyolifin membrane which is coated with a layer of from 50 A to 1000 A of low hydrogen overpotential material having a hydrogen overpotential in alkaline solution lower than that of zinc, and (b) a semipermeable active layer of hydroxyl-containing polymer covering the layer of low hydrogen overpotential material; (2) two protective layers comprising microporous polyolifin membranes, the barrier layer being sandwiched between the two protective layers; D. an alkaline electrolyte; E. means for terminating the charging of the cell when the internal gas pressure of the cell reaches a preselected value; and F. means for venting the cell if the internal gas pressure reaches a preselected value above that at which the charging of the cell is terminated.

Claim 23

The sealed alkaline nickel-zinc cell of claim 19 which has means for terminating the charging of the cell when the internal gas pressure reaches a preselected value in the range of from 5.0 to 8.0 psig.

Claim 24

The sealed alkaline nickel-zinc cell of claim 20 wherein means are provided for venting the cell when the internal gas pressure of the cell reaches 10.0±0.5 psig.

Claim 25

A sealed alkaline nickel-zinc cell according to claim 19, 20, or 21 wherein the coating of low hydrogen overpotential material in the separator is from 100 A to 500 A thick.

Claim 26

A sealed nickel-zinc cell according to claim 19, 20, or 21 wherein the low hydrogen overpotential material in the separator is nickel.

Claim 27

A sealed nickel-zinc cell according to claim 19, 20, or 21 wherein the low hydrogen overpotential material in the separator is stainless steel.

Claim 28

A sealed nickel-zinc cell according to claim 19, 20, or 21 wherein the average pore sizes of the microporous polyolifins in the separator are from 100 A to 500 A.

Claim 29

A sealed nickel-zinc cell according to claim 19, 20, or 21 wherein the semipermeable active layers of hydroxyl-containing polymer in the separator has an average pore size of from 10 A to 50 A.

Claim 30

A sealed nickel-zinc cell according to claim 19, 20, or 21 wherein the semipermeable active layer of a hydroxyl-containing polymer in the separator has an average pore size of from 15 A to 25 A.