Electrolyte-absoring, non-permeable sealing materials
View Patent ↗An engineered thermoplastic sealing member for LiFeS 2 and other nonaqueous cells is disclosed. The optimal material displays a propensity to absorb at least 10 weight percent of an ether-based electrolyte while, at the same time, displaying a vapor transmission rate of less than 500((g×mil)/(100 in 2 ×days).
1. A lithium iron disulfide battery comprising:
a jellyroll electrode assembly comprising an anode consisting of lithium or a lithium alloy, a cathode including iron disulfide coated onto a current collector and a separator disposed between the anode and the cathode;
an electrolyte consisting essentially of one or more organic solvents and at least one solute dissolved therein, said one or more organic solvents including at least 50 volume percent of one or more ethers;
a housing;
a closure assembly affixed over an opening in the housing; and
at least one sealing member disposed between the housing and the closure assembly, said sealing member made from an engineered thermoplastic comprising PPS mixed with at least 10 weight percent of a thermal stabilizing filler;
wherein the engineered thermoplastic has an absorption at 71° C. greater than or equal to 10 weight percent and a vapor transmission rate of less than 500(g×mil)/(100 in 2 ×day), said absorption and vapor transmission rate both relative to the electrolyte.
2. The battery of claim 1 wherein the one or more ethers are selected from the group consisting of: 1,2-dimethoxyethane, 1,2-diethoxyethane, di(methoxyethyl)ether, triglyme, tetraglyme, diethyl ether, 1,3-dioxolane, tetrahydrofuran, 2-methyl tetrahydrofuran, 3-methyl-2-oxazolidinone and combinations thereof.
3. The battery of claim 2 wherein the electrolyte consists of at least 90 volume percent of the one or more ethers.
4. The battery of claim 2 wherein the at least one solute selected from the group consisting of: lithium bromide, lithium perchlorate, lithium hexafluorophosphate, potassium hexafluorophosphate, lithium hexafluoroarsenate, lithium trifluoromethanesulfonate, lithium iodide and combinations thereof.
5. The battery of claim 1 wherein the engineered thermoplastic is PPS with between 10 and 40 weight percent of an impact modifier and between 0 and 35 weight percent of a thermal stabilizing filler.
6. The sealing member of claim 5 wherein the engineered thermoplastic is semi-crystalline.