Recombinant separator
A heterogeneous, cellulose battery separator made of a mixture of cellulose and a polymer with hydrogen permeability for use in zinc-based batteries exhibiting increased hydrogen transport through the membrane while maintaining low electrical impedance and exhibiting resistance to zinc ion transport preventing zinc dendrite formation.
1 . A method of forming a recombinant separator for a zinc ion battery comprising the steps of;
dissolving cellulose in a first solvent to form a first solution;
dissolving a polymer having a hydrogen permeability of at least 1×10 −13 cm 3 cm −1 s −1 Pa −1 in a second solvent to form a second solution;
combining the solutions into a third solution;
forming a film of the third solution containing domains of the polymer dispersed in the cellulose; and
drying the film to form said separator.
2 . A method according to claim 1 in which the domains are formed in the film by coagulating the film in presence of water or alcohol.
3 . A method according to claim 2 in which water is indirectly applied to the film.
4 . A method according to claim in which the ambient atmosphere above the film during coagulation has a relative humidity from 35 to 80%.
5 . A method according to claim 4 further including the step of maintaining the ambient atmosphere at a temperature of 15 to 30 degrees Celsius during coagulation.
6 . A method according to claim 1 in which the film is washed to remove solvent before drying.
7 . A method according to claim 1 in which the polymer is present in the film in an amount of from 10 to 60 parts by weight of polymer to 100 parts by weight of cellulose.
8 . A method according to claim 1 in which the cellulose is selected from the group consisting of microcrystalline cellulose, cotton fiber, paper, microgranular cellulose and crosslinked cellulose.
9 . A method according to claim 8 in which the cellulose has a degree of polymerization from 200 to 2500.
10 . A method according to claim 9 in which the cellulose is crosslinked with a hydrocarbon bridge containing from 2 to 12 carbon atoms between cellulose chains.
11 . A method according to claim 10 in which the bridge is an alkylene bridge containing from 4 to 8 carbon atoms.
12 . A method according to claim 1 in which the film is formed by casting.
13 . A method according to claim 12 in which the film has a thickness from 10 microns to 250 microns.
14 . A method according to claim 1 in which the first solvent is a mixture of an inorganic salt and a polar aprotic solvent.
15 . A method according to claim 14 in which the second solvent is a miscible polar, aprotic solvent.
16 . A method according to claim 1 in which the polymer is a cellulose ether.
17 . A method according to claim 16 in which the polymer is alkyl cellulose.
18 . A method according to claim 17 in which the polymer is ethyl cellulose.
19 . (canceled)
20 . (canceled)
21 . (canceled)
22 . (canceled)
23 . (canceled)
24 . (canceled)
25 . (canceled)
26 . (canceled)
27 . (canceled)
28 . (canceled)
29 . (canceled)
30 . (canceled)
31 . (canceled)