# US 9,517,939 B2 · Method of enhancing the connectivity of a colloidal template, and a highly interconnected porous structure

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- Number: US 9,517,939 B2
- Document ID: US9517939B2
- Status: Granted
- Kind: B2
- Application number: 13/467,419
- Filed: 2012-05-09
- Published: 2013-11-14
- Granted: 2016-12-13
- Earliest claimed: 2012-05-09
- Assignees: The Board of Trustees of the University of Illinois
- Applicants: Paul V. Braun; Hui Gang Zhang
- Inventors: Paul V. Braun; Hui Gang Zhang
- Web page: https://patentgrep.com/patent/US9517939B2

## CPC

- C01B 33/18: Preparation of finely divided silica neither in sol nor in gel form; After-treatment thereof (preparation of aerogels by dehydrating gels C01B33/158; treatment to enhance the pigmenting or filling properties C09C)
- H01M 4/801: {Sintered carriers}
- C01P 2004/03: obtained by SEM
- C01P 2004/34: hollow
- C08G 77/04: Polysiloxanes
- H01M 4/661: {Metal or alloys, e.g. alloy coatings (H01M4/669 take precedence)}
- H01M 4/667: {in the form of layers, e.g. coatings}
- Y02E 60/10: Energy storage using batteries
- Y10T 428/249921: Web or sheet containing structurally defined element or component
- 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
- C01P: INDEXING SCHEME RELATING TO STRUCTURAL AND PHYSICAL ASPECTS OF SOLID INORGANIC COMPOUNDS
- C08G: MACROMOLECULAR COMPOUNDS OBTAINED OTHERWISE THAN BY REACTIONS ONLY INVOLVING UNSATURATED CARBON-TO-CARBON BONDS
- Y02E: REDUCTION OF GREENHOUSE GAS [GHG] EMISSIONS, RELATED TO ENERGY GENERATION, TRANSMISSION OR DISTRIBUTION
- Y10T: TECHNICAL SUBJECTS COVERED BY FORMER US CLASSIFICATION

## Abstract

A method of enhancing the connectivity of a colloidal template includes providing a lattice of microparticles, where the microparticles are in contact with adjacent microparticles at contact regions therebetween, and exposing the lattice to a solution comprising a solvent and a precursor material. The solvent is removed from the solution, and the precursor material moves to the contact regions. A ring is formed from the precursor material around each of the contact regions, thereby creating interconnects between adjacent microparticles and enhancing the connectivity of the lattice.

## Claims

### Claim 1

A method of forming a conductive porous structure, the method comprising:
forming a lattice of microparticles from a suspension of microparticles by self-assembly and drying, the microparticles of the lattice being in contact with adjacent microparticles of the lattice at contact regions therebetween;
after forming the lattice of microparticles by self-assembly and drying, annealing the lattice to strengthen the contact between adjacent microparticles, thereby forming an annealed lattice of microparticles;
after the annealing, exposing the annealed lattice to a solution comprising a solvent and a precursor material;
removing the solvent from the solution, the precursor material moving to the contact regions;
after removing the solvent, curing the precursor material to form a ring comprising a polymer around each of the contact regions, thereby creating interconnects between adjacent microparticles of the annealed lattice and enhancing the connectivity of the annealed lattice;
after forming the ring around each of the contact regions, heating the rings at a temperature of from about 200° C. to about 500° C. to transform the rings into calcined rings comprising SiO2;
after heating the rings, infilling the annealed lattice with a conductive material, the conductive material coating the microparticles of the annealed lattice and the interconnects; and
after the infilling, removing the microparticles of the annealed lattice and the interconnects to obtain a monolithic porous structure comprising the conductive material and including (a) voids defined by the microparticles and (b) necks between the voids defined by the interconnects.

### Claim 2 (depends on 1)

The method of claim 1, wherein curing the precursor material comprises heating the precursor material at temperature of from about 50° C. to about 200° C.

### Claim 3 (depends on 1)

The method of claim 1, wherein curing the precursor material comprises chemically treating the precursor material.

### Claim 4 (depends on 1)

The method of claim 1, wherein the polymer comprises silicon.

### Claim 5 (depends on 4)

The method of claim 4, wherein the polymer is selected from the group consisting of: polysiloxanes, polycarbosilanes, polysilazanes, and polysilanes.

### Claim 6 (depends on 5)

The method of claim 5, wherein the polymer is a polysiloxane selected from the group consisting of: polydimethylsiloxane and poly(methylsilsesquioxane).

### Claim 7 (depends on 1)

The method of claim 1, wherein the precursor material is present in the solution at a concentration of from about 1 wt. % to about 20 wt. %.

### Claim 8 (depends on 1)

The method of claim 1, wherein the solution further comprises a curing agent.

### Claim 9 (depends on 1)

The method of claim 1, wherein the solvent is selected from the group consisting of water, ethanol, methanol, isopropyl alcohol, acetone, methyl ethyl ketone, acetonitrile, toluene, pentane, hexane, heptane, xylene, and benzene.

### Claim 10 (depends on 1)

The method of claim 1, wherein a ratio of an outer diameter of each of the rings to a diameter of each of the microparticles is at least about 0.1.

### Claim 11 (depends on 10)

The method of claim 10, wherein the ratio is from about 0.1 to about 0.8.

### Claim 12 (depends on 1)

The method of claim 1, wherein the microparticles comprise SiO2.

### Claim 13 (depends on 1)

The method of claim 1, wherein the microparticles comprise a polymer.

### Claim 14 (depends on 1)

The method of claim 1, wherein the annealed lattice is disordered.

### Claim 15 (depends on 1)

The method of claim 1, further comprising, after the removing, depositing an electrochemically active material on the monolithic porous structure, thereby forming a porous battery electrode.

### Claim 16 (depends on 1)

The method of claim 1, further comprising, after the removing, chemically transforming the conductive material to comprise an electrochemically active material, thereby forming a porous battery electrode.

### Claim 17

A method of forming a conductive porous structure, the method comprising:
forming a lattice of microparticles from a suspension of microparticles by self-assembly and drying, the microparticles of the lattice being in contact with adjacent microparticles of the lattice at contact regions therebetween;
after forming the lattice of microparticles by self-assembly and drying, annealing the lattice to strengthen the contact between adjacent microparticles, thereby forming an annealed lattice of microparticles;
after the annealing, exposing the annealed lattice to a solution comprising a solvent and a precursor material;
removing the solvent from the solution, the precursor material moving to the contact regions;
after removing the solvent, curing the precursor material to form a ring comprising a polymer around each of the contact regions, thereby creating interconnects between adjacent microparticles of the annealed lattice and enhancing the connectivity of the annealed lattice;
after forming the ring around each of the contact regions, infilling the annealed lattice with a conductive material, the conductive material coating the microparticles of the annealed lattice and the interconnects;
after the infilling, removing the microparticles of the annealed lattice and the interconnects to obtain a monolithic porous structure comprising the conductive material and including (a) voids defined by the microparticles and (b) necks between the voids defined by the interconnects; and
after removing the microparticles, depositing an electrochemically active material on the monolithic porous structure, thereby forming a porous battery electrode.

### Claim 18

A method of forming a conductive porous structure, the method comprising:
forming a lattice of microparticles from a suspension of microparticles by self-assembly and drying, the microparticles of the lattice being in contact with adjacent microparticles of the lattice at contact regions therebetween;
after forming the lattice of microparticles by self-assembly and drying, annealing the lattice to strengthen the contact between adjacent microparticles, thereby forming an annealed lattice of microparticles;
after the annealing, exposing the annealed lattice to a solution comprising a solvent and a precursor material;
removing the solvent from the solution, the precursor material moving to the contact regions;
after removing the solvent, curing the precursor material to form a ring comprising a polymer around each of the contact regions, thereby creating interconnects between adjacent microparticles of the annealed lattice and enhancing the connectivity of the annealed lattice;
after forming the ring around each of the contact regions, infilling the annealed lattice with a conductive material, the conductive material coating the microparticles of the annealed lattice and the interconnects;
after the infilling, removing the microparticles of the annealed lattice and the interconnects to obtain a monolithic porous structure comprising the conductive material and including (a) voids defined by the microparticles and (b) necks between the voids defined by the interconnects; and
after removing the microparticles, chemically transforming the conductive material to comprise an electrochemically active material, thereby forming a porous battery electrode.