Mesoporous polyimide thin films as dendrite-suppressing separators for alkali metal batteries

Patent metadata

Field	Value
Publication number	US-2025367613-A1
Application number	US-202318865629-A
Country	US
Kind code	A1
Filing date	May 13, 2023
Priority date	May 13, 2022
Publication date	Dec 4, 2025
Grant date	—

Abstract

In various aspects, methods of preparing mesoporous polyimide membranes are provided. The polyimide membranes are useful as separators in various electrochemical devices, in particular in alkali metal batteries where the controllable pore size and high modulus of the membranes can prevent or suppress dendrite formation in alkali metal batteries. Electrochemical devices, and in particular alkali metal batteries, incorporating the polyimide membranes as separators are also provided.

First claim

1 . A method of preparing a mesoporous polyimide membrane comprising:
a) casting an A-B, A-B-A, or A-B-C block copolymer on a substrate to form a precursor film, wherein A and C are each independently thermally labile blocks, and wherein B is a polyimide block; b) heating the precursor film to a temperature from about 100° C. to about 300° C. for a time interval to form the polyimide membrane; wherein the mesoporous polyimide membrane comprises a plurality of mesopores wherein a median diameter of the mesopores is from about 5 nm to about 20 nm as measured by the Nitrogen Sorption Protocol.

2 . The method of claim 1 , further comprising prior to the casting step:
(i) preparing an A-D, A-D-A, or A-D-C block copolymer, wherein A and C are each independently thermally labile blocks and D is a poly(amic acid) block; and ii) treating the A-D, A-D-A, or A-D-C block copolymer with an anhydride and a base to form the A-B, A-B-A, or A-B-C block copolymer.

3 . The method of claim 1 , wherein the thermally labile blocks are each independently selected from the group consisting of a polyacrylate, a vinyl polymer, a styrenic polymer, a polyester, and a polyether.

4 . The method of claim 1 , further comprising prior to the casting step:
(i) preparing a polylactide-b-poly(amic acid)-b-polylactide (PLA-b-PAA-b-PLA) triblock copolymer; and (ii) treating the PLA-b-PAA-b-PLA triblock copolymer with an anhydride and a base to form the A-B-A triblock copolymer.

5 . The method of claim 1 , further comprising prior to the casting step:
(i) preparing a polylactide-b-poly(amic acid) (PLA-b-PAA) diblock copolymer; and (ii) treating the PLA-b-PAA diblock copolymer with an anhydride and a base to form the A-B block copolymer.

6 . The method of claim 1 wherein one or both of the thermally labile blocks are polyacrylates selected from the group consisting of a polyethyl acrylate (PEA), a poly(n-butyl acrylate) (PBA), a poly(methyl acrylate) (PMA), a poly(methyl methacrylate) (PMMA), a poly(2-hydroxyethyl acrylate) (PHEA), and copolymers thereof.

7 . The method of claim 1 , wherein one or both of the thermally labile blocks are vinyl polymers selected from the group consisting of a polyvinyl alcohol (PVA), a polyvinyl acetate (PVAc), a polyvinyl chloride (PVC), a polyvinylidine chloride (PVDC), and copolymers thereof.

8 . The method of claim 1 , wherein one or both of the thermally labile blocks are styrenic polymers selected from the group consisting of polystyrene (PS), poly(styrene-acrylonitrile) (SAN), poly(styrene-butadiene-styrene) (SBS), poly(styrene-ethylene/butyliene-styrene) (SEBS), and copolymers thereof.

9 . The method of claim 1 , wherein one or both of the thermally labile blocks are polyesters selected from the group consisting of a polyethylene terephthalate (PET), a polybutylene adipate-co-terephthalate (PBAT), a polytrimethylene terephthalate (PTT), a polyethylene succinate (PES), and copolymers thereof.

10 . The method of claim 1 , wherein one or both of the thermally labile blocks are polyethers selected from the group consisting of a polyethylene oxide (PEO), a polypropylene oxide (PPO), a poly(tetramethylene ether)glycol (PTMEG), a poly(ethylene-co-propylene glycol) (PPEG), and copolymers thereof.

11 . The method of claim 1 , wherein the thermally labile blocks comprise polylactide.

12 . The method of claim 1 , wherein the thermally labile block has a thermolysis temperature of about 270° C., about 250° C., about 230° C., about 200° C., or less.

13 . (canceled)

14 . The method of claim 1 , wherein a median pore width of the mesopores is from about 10 nm to about 40 nm.

15 . (canceled)

16 . The method of claim 1 , wherein the membrane has a thickness of from about 5 to about 50 microns.

17 . (canceled)

18 . (canceled)

19 . The method of claim 1 , wherein the time interval comprises about thirty minutes to about 48 hours, about 30 minutes to about 3 hours, or about 12 hours to about 36 hours.

20 . The method of claim 1 wherein the temperature is from about 100° C. to below 280° C.

21 . (canceled)

22 . A mesoporous polyimide membrane comprising a polyimide membrane having a plurality of mesopores,
wherein a median diameter of the mesopores is from about 5 nm to about 20 nm as measured by the Nitrogen Sorption Protocol, and wherein the mesopores are isoporous.

23 . The mesoporous polyimide membrane of claim 22 wherein the mesoporous polyimide membrane has a storage modulus of from 1.5 to 2.5 GPa as measured by the Storage Modulus Protocol.

24 . (canceled)

25 . (canceled)

26 . (canceled)

27 . (canceled)

28 . The mesoporous polyimide membrane of claim 22 wherein the membrane thickness is from about 20 to about 25 microns.

29 . (canceled)

30 . An electrochemical device comprising:
(a) an anode; (b) a cathode; (c) the electrochemical cell separator material comprising the mesoporous polyimide membrane of claim 22 mounted between the anode and the cathode; and (d) an electrolyte.

31 - 54 . (canceled)

Assignees

• Virginia Tech Intellectual Properties Inc

Inventors

• Liu Guoliang
• Guo Dong

Classifications

• B01D67/0011

  Casting solutions therefor · CPC title

• B01D2325/02832

  1-10 nm · CPC title

• B01D2325/02833

  more than 10 and up to 100 nm · CPC title

• H01M50/414

  Synthetic resins, e.g. thermoplastics or thermosetting resins · CPC title

• Y02E60/10

  Energy storage using batteries · CPC title