Thin battery separators and methods

A multilayer shutdown battery separator that comprises a microporous membrane comprising:

• at least two coextruded dry-stretch process polypropylene (PP) or polyethylene (PE) layers, wherein the microporous membrane has a thickness of 9.5 to 12 μm, of 6.5 to 9.5 μm, of 5.5 to 6.5 μm, or of 3.5 to 5.5 μm, and wherein the microporous membrane has shutdown function.

A multilayer shutdown battery separator that comprises a microporous membrane comprising:

• at least two coextruded dry-stretch process polypropylene (PP) or polyethylene (PE) layers, wherein the microporous membrane has a thickness of 9.5 to 12 μm, of 6.5 to 9.5 μm, of 5.5 to 6.5 μm, or of 3.5 to 5.5 μm, wherein the microporous membrane has shutdown function, wherein the PE pore size of at least one of the dry-stretch process polyethylene (PE) layers is <0.1 μm, and wherein the PP pore size of at least one of the dry-stretch process polypropylene (PP) layers is 0.02 μm-0.05 μm.

A multilayer shutdown battery separator that comprises a microporous membrane comprising:

• at least three coextruded dry-stretch process polypropylene (PP) or polyethylene (PE) layers, wherein the microporous membrane has a thickness of 9.5 to 12 μm, of 6.5 to 9.5 μm, of 5.5 to 6.5 μm, or of 3.5 to 5.5 μm, wherein the microporous membrane has shutdown function, wherein the PE pore size of at least one of the dry-stretch process polyethylene (PE) layers is <0.1 μm, and wherein the PP pore size of at least one of the dry-stretch process polypropylene (PP) layers is 0.02 μm-0.05 μm.

A multilayer shutdown battery separator that comprises a microporous membrane comprising:

• at least four coextruded dry-stretch process polypropylene (PP) or polyethylene (PE) layers, wherein the microporous membrane has a thickness of 9.5 to 12 μm, of 6.5 to 9.5 μm, of 5.5 to 6.5 μm, or of 3.5 to 5.5 μm, wherein the microporous membrane has shutdown function, wherein the PE pore size of at least one of the dry-stretch process polyethylene (PE) layers is <0.1 μm, and wherein the PP pore size of at least one of the dry-stretch process polypropylene (PP) layers is 0.02 μm-0.05 μm.

A multilayer shutdown battery separator that comprises a microporous membrane comprising:

• at least five coextruded dry-stretch process polypropylene (PP) or polyethylene (PE) layers, wherein the microporous membrane has a thickness of 9.5 to 12 μm, of 6.5 to 9.5 μm, of 5.5 to 6.5 μm, or of 3.5 to 5.5 μm, wherein the microporous membrane has shutdown function, wherein the PE pore size of at least one of the dry-stretch process polyethylene (PE) layers is <0.1 μm, and wherein the PP pore size of at least one of the dry-stretch process polypropylene (PP) layers is 0.02 μm-0.05 μm.