Smart battery separators
View Patent ↗A separator for an energy storage cell that is provided by a microporous web that includes an irreversible porosity-controlling agent a method for changing an operating characteristic of an energy storage cell.
1. A separator for a lead acid battery comprising a microporous web wherein the web further comprises a flexible rubber separator and is characterized by containing an irreversible porosity-controlling agent selected from the group consisting of microspheres derived from poly(vinylidene chloride-co-acrylonitrile) materials or methacrylonitrile-acrylonitrile materials, and wherein the porosity-controlling agent is effective to irreversibly decrease the porosity of the separator and increase the electrical resistance of the separator as the battery ages.
2. The separator of claim 1 , wherein the microporous web comprises a non-woven fibrous matrix.
3. The separator of claim 1 , wherein the microporous web comprises a web made from a mixture of a polymer and silica.
4. The separator of claim 1 , wherein the porosity-controlling agent is selected from the group consisting of agents that change size as a function of temperature, pH, and/or pressure to provide a change in an overall porosity of the separator.
5. The separator of claim 1 , wherein the microspheres comprise fluid-filled microspheres.
6. The separator of claim 5 , wherein the separator comprises from about 5 to about 50 percent by weight of the fluid-filled microspheres.
7. The separator of claim 2 , wherein the non-woven fibrous matrix comprises a glass mat fibrous matrix.
8. The separator of claim 2 , wherein the non-woven fibrous matrix comprises a polyolefin fibrous matrix.
9. A method for changing an operating characteristic of a lead acid battery during battery as the battery ages, characterized by:
applying from about 5 to about 50 weight percent of an irreversible porosity controlling agent to a separator material;
forming a separator from the separator material and porosity-controlling agent; and
operating the lead acid battery with the separator,
wherein the porosity-controlling agent is selected from the group consisting of microspheres derived from poly(vinylidene chloride-co-acrylonitrile) materials or methacrylonitrile-acrylonitrile materials, and wherein the porosity-controlling agent is effective to irreversibly decrease the porosity of the separator and increase the electrical resistance of the separator as the battery ages.
10. The method of claim 9 , wherein the porosity controlling agent is selected from the group consisting of agents that change size as a function of temperature, pH, and/or pressure to provide a change in an overall porosity of the separator.