# US 10,864,485 B2 · Asymmetric membranes

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- Number: US 10,864,485 B2
- Document ID: US10864485B2
- Status: Granted
- Kind: B2
- Application number: 16/566,466
- Filed: 2019-09-10
- Published: 2020-01-02
- Granted: 2020-12-15
- Earliest claimed: 2016-05-02
- Assignees: Georgia Southern Research and Service Foundation
- Applicants: Georgia Southern Research and Service Foundation, Inc.
- Inventors: Ji Wu; Hao Chen; Ian Byrd
- Web page: https://patentgrep.com/patent/US10864485B2

## CPC

- B01D 71/0213: {Silicon}
- B01D 67/0067: {by carbonisation or pyrolysis}
- B01D 71/0211: {Graphene or derivates thereof}
- B01D 71/0212: {Carbon nanotubes}
- C01B 32/158: Carbon nanotubes
- H01M 4/0471: {involving thermal treatment, e.g. firing, sintering, backing particulate active material, thermal decomposition, pyrolysis}
- H01M 4/133: Electrodes based on carbonaceous material, e.g. graphite-intercalation compounds or CFx
- H01M 4/134: Electrodes based on metals, Si or alloys
- H01M 4/1393: of electrodes based on carbonaceous material, e.g. graphite-intercalation compounds or CFx
- H01M 4/1395: of electrodes based on metals, Si or alloys
- H01M 4/364: {as mixtures}
- H01M 4/386: {Silicon or alloys based on silicon}
- H01M 4/483: {for non-aqueous cells (H01M4/485 takes precedence)}
- H01M 4/663: {containing carbon or carbonaceous materials as conductive part, e.g. graphite, carbon fibres}
- H01M 4/80: Porous plates, e.g. sintered carriers
- B01D 69/02: characterised by their properties
- B01D 2325/023: Dense layer within the membrane
- B01D 2325/04: Characteristic thickness
- B01D 2325/26: Electrical properties
- H01M 10/0525: Rocking-chair batteries, i.e. batteries with lithium insertion or intercalation in both electrodes; Lithium-ion batteries
- H01M 2004/021: {Physical characteristics, e.g. porosity, surface area}
- Y02E 60/10: Energy storage using batteries
- B01D: SEPARATION (separating solids from solids by wet methods B03B, B03D; by pneumatic jigs or tables B03B; by other dry methods B07; magnetic or electrostatic separation of solid materials from solid materials or fluids, separation by high-voltage electric fields B03C; centrifuges, vortex apparatus B04; presses per se for squeezing-out liquid from liquid-containing material B30B9/02; treatment of water C02F, e.g. softening by ion-exchange C02F1/42; {arrangements of air intake cleaners in gas turbine plants F02C7/05} ; arrangements or mounting of filters in air-conditioning, air-humidification or ventilation F24F13/28)
- C01B: NON-METALLIC ELEMENTS; COMPOUNDS THEREOF; {METALLOIDS OR COMPOUNDS THEREOF NOT COVERED BY SUBCLASS C01C}
- H01M: PROCESSES OR MEANS, e.g. BATTERIES, FOR THE DIRECT CONVERSION OF CHEMICAL ENERGY INTO ELECTRICAL ENERGY
- Y02E: REDUCTION OF GREENHOUSE GAS [GHG] EMISSIONS, RELATED TO ENERGY GENERATION, TRANSMISSION OR DISTRIBUTION

## Abstract

Disclosed herein are porous asymmetric silicon membranes. The membranes are characterized by high structural stability, and as such are useful as anode components in lithium ion batteries.

## Claims

### Claim 1

A process for preparing an asymmetric membrane comprising:
a) coating a surface of a substrate with a mixture comprising a lithium storage material or source thereof, (para)crystalline carbon, carbonizable polymer and a first solvent comprising one or more water soluble organic solvents;
b) immersing the coated substrate in a second solvent to generate a film, wherein the second solvent is more polar than the first solvent; and
c) heating the film under conditions sufficient to carbonize the carbonizable polymer.

### Claim 2 (depends on 1)

The process according to claim 1, wherein the lithium storage material comprises silicon, tin dioxide, vanadium pentoxide, or a combination thereof.

### Claim 3 (depends on 1)

The process according to claim 1, wherein the lithium storage material source comprises tin alkoxides, tin acetates, tin acetotacetates, vanadaium alkoxides, vanadium acetates, vanadium acetoacetates, or a combination thereof.

### Claim 4 (depends on 1)

The process according to claim 1, wherein the paracrystalline carbon comprises carbon black, fullerenes, nanotubes, graphite, graphene, or mixtures thereof.

### Claim 5 (depends on 1)

The process according to claim 1, wherein the carbonizable polymer comprises cellulose acetates, phenolic resins, polyacrylonitriles, resorcinol-formaldehydes, polysulfones, polyamides, polyvinyls, polyimides, or a combination thereof.

### Claim 6 (depends on 1)

The process according to claim 1, wherein the first solvent comprises NMP, DMF, DMSO, THF, Et2O, a C1-4carboxylic acid, a halogenated C1-4carboxylic acid, acetone, MEK, EtOAc, a C1-4alkyl alcohol, or a combination thereof.

### Claim 7 (depends on 1)

The process according to claim 1, wherein prior to carbonization, further comprising:
a) contacting the as formed film with a mixture comprising:
1) amorphous carbon or carbonizable polymer;
2) paracrystalline carbon;
3) a water soluble organic solvent; and
b) performing a phase inversion with a suitable anti-solvent.

### Claim 8 (depends on 7)

The process according to claim 7, wherein the carbonizable polymer comprises cellulose acetates, phenolic resins, polyacrylonitriles, resorcinol-formaldehydes, polysulfones, polyamides, polyvinyls, polyimides, or a combination thereof.

### Claim 9 (depends on 7)

The process according to claim 7, wherein the contacting comprises immersing the film in a mixture of amorphous carbon or carbonizable polymer; paracrystalline carbon; and a water soluble organic solvent.

### Claim 10 (depends on 7)

The process according to claim 7, wherein the contacting comprises coating the mixture on a single side of the film.

### Claim 11 (depends on 1)

The process according to claim 1, wherein the heating is conducted at a temperature of at least 600° C. for a period of at least 0.5 hours.

### Claim 12 (depends on 1)

The process according to claim 1, further comprising contacting the carbonized film with a solution comprising a conductive polymer.