# US 9,437,870 B2 · Nano-silicon composite lithium ion battery anode material coated with poly (3,4-ethylenedioxythiophene) as carbon source and preparation method thereof

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- Number: US 9,437,870 B2
- Document ID: US9437870B2
- Status: Granted
- Kind: B2
- Application number: 14/131,385
- Filed: 2011-08-26
- Published: 2014-04-24
- Granted: 2016-09-06
- Earliest claimed: 2011-07-15
- Assignees: Guangzhou Institute of Energy Conversion
- Applicants: Lingzhi Zhang; Lu Yue; Suqing Wang; Xinyue Zhao
- Inventors: Lingzhi Zhang; Lu Yue; Suqing Wang; Xinyue Zhao
- Web page: https://patentgrep.com/patent/US9437870B2

## CPC

- H01M 4/366: {as layered products}
- 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 4/1395: of electrodes based on metals, Si or alloys
- H01M 4/386: {Silicon or alloys based on silicon}
- H01M 10/0525: Rocking-chair batteries, i.e. batteries with lithium insertion or intercalation in both electrodes; Lithium-ion batteries
- Y02E 60/10: Energy storage using batteries
- Y02T 10/70: Energy storage systems for electromobility, e.g. batteries
- H01M: PROCESSES OR MEANS, e.g. BATTERIES, FOR THE DIRECT CONVERSION OF CHEMICAL ENERGY INTO ELECTRICAL ENERGY
- C01B: NON-METALLIC ELEMENTS; COMPOUNDS THEREOF; {METALLOIDS OR COMPOUNDS THEREOF NOT COVERED BY SUBCLASS C01C}
- Y02E: REDUCTION OF GREENHOUSE GAS [GHG] EMISSIONS, RELATED TO ENERGY GENERATION, TRANSMISSION OR DISTRIBUTION
- Y02T: CLIMATE CHANGE MITIGATION TECHNOLOGIES RELATED TO TRANSPORTATION

## Abstract

A high-performance new silicon composite material for a negative electrode of a lithium ion battery and a preparation method thereof by utilizes a conductive polymer PEDOT and a water solution dispersant PSS as a coating layer of nano-Si powder and a carbon source. The Si/C composite material taking a Si-containing type lithium storage material as a main active substance is prepared by firstly polymerizing PEDOT: PSS on the surface of Si through in-situ polymerization reaction and then performing high-temperature carbonization treatment on a prepared Si/PEDOT: PSS composite under an inert atmosphere. The prepared composite material is doped with a small amount of S element. Nano-Si particles are uniformly embedded in a PEDOT: PSS polymer and a carbon matrix. A high yield is achieved by using cheap raw materials and a simple and environment-friendly process. The prepared Si/C composite material has very low initial irreversible capacity loss (2.8%) and excellent charge-discharge.

## Claims

### Claim 1

A silicon/carbon composite material as a negative electrode for a lithium ion battery, having a nano-silicon powder as an active substance, and a carbon coating outside the nano-silicon powder being S-doped carbon, the S-doped carbon being obtained by carbonization of substances including a conductive polymer poly(3,4-ethylenedioxythiophene) and polystyrene sulfonic acid as a dispersant of poly(3,4-ethylenedioxythiophene), said silicon/carbon composite material as the negative electrode for the lithium ion battery being prepared using a method comprising the steps of:
(1) adding a precursor monomer 3,4-ethylenedioxythiophene into a water solution of the polystyrene sulfonic acid and performing homogeneous dispersion treatment;
(2) adding the nano-silicon powder to a solution obtained in step (1), and then performing ultrasonic dispersion and uniformly stirring;
(3) adjusting the pH value of the solution in step (2) by using 2M hydrochloric acid;
(4) dropwise adding a water solution of (NH4)2S2O8/FeCl3 into the solution in the step (3) under an ice bath condition for being used as a catalyst;
(5) firstly subjecting the mixed solution in the step (4) to an ice bath for 6 hours and then reacting at room temperature for 18 hours, and filtering to get a Si/PEDOT: PSS composite; and
(6) heating the Si/PEDOT: PSS composite to 800-1000° C. under protective gas, performing heat preservation and carbonization, and cooling after an end of a reaction.

### Claim 2 (depends on 1)

The silicon/carbon composite material as a negative electrode for a lithium ion battery according to claim 1, wherein the carbonization is for 3 hours.

### Claim 3

A preparation method of a silicon/carbon composite material for a negative electrode of a lithium ion battery comprising the steps of:
(1) adding precursor monomers 3,4-ethylenedioxythiophene into a water solution of polystyrene sulfonic acid and performing homogeneous dispersion treatment;
(2) adding nano-silicon powder to a solution obtained in step (1), and then performing ultrasonic dispersion and uniformly stirring;
(3) regulating the pH value of the solution in step (2) by using 2M hydrochloric acid;
(4) dropwise adding a water solution of (NH4)2S2O8/FeCl3 into the solution in the step (3) under an ice bath condition for being used as a catalyst;
(5) firstly subjecting the mixed solution in step (4) to an ice bath for 6 hours and then reacting at room temperature for 18 hours, and filtering to get a Si/PEDOT: PSS composite; and
(6) heating the Si/PEDOT: PSS composite to 800-1000° C. under Ar gas, performing heat preservation and carbonization, and cooling after an end of a reaction.

### Claim 4 (depends on 3)

The preparation method of the silicon/carbon composite material for the negative electrode of the lithium ion battery according to claim 3, wherein an adding amount of Si is 1-2 times a mass of the precursor monomers 3,4-ethylenedioxythiophene, an adding amount of (NH4)2S2O8 is 1.5-3 times the mass of the precursor monomers 3,4-ethylenedioxythiophene, an adding amount of FeCl3 is 0.01-0.05 time the mass of the precursor monomers 3,4-ethylenedioxythiophene, and an adding amount of an PSS is 1.5-4 times the mass of the precursor monomers 3,4-ethylenedioxythiophene.

### Claim 5 (depends on 3)

The preparation method of the silicon/carbon composite material for the negative electrode of the lithium ion battery according to claim 3, wherein the carbonization is for 3 hours.