Low cost Si-based negative electrodes with enhanced cycling performance

Patent metadata

Field	Value
Publication number	US-9692044-B2
Application number	US-201314394779-A
Country	US
Kind code	B2
Filing date	Apr 4, 2013
Priority date	Apr 17, 2012
Publication date	Jun 27, 2017
Grant date	Jun 27, 2017

Abstract

A rechargeable battery comprising a positive electrode, a negative electrode and an electrolyte, wherein: —the electrolyte comprises a SEI film-forming agent, and—the negative electrode comprises a micrometric Si based active material, a polymeric binder material and a conductive agent, wherein at least part of the surface of the Si based active material consists of Si—OCO—R groups, Si being part of the active material, and R being the polymeric chain of the binder material.

First claim

The invention claimed is:

1. A process for preparing a rechargeable battery comprising a positive electrode, a negative electrode and an electrolyte, comprising:
providing a battery container, a current collector and a separator,
providing a positive electrode,
providing an electrolyte comprising an SEI-film forming agent, wherein the SEI film-forming agent is selected from one or more of the group consisting of fluoro ethylene carbonate, vinylidene carbonate, vinyl ethylene carbonate, phenyl ethylene carbonate, phenylvinylene carbonate, catechol carbonate, allyl methyl carbonate, allyl ethyl carbonate, vinyl acetate, acrylonitrile and 2-cyanofuran,
providing a negative electrode comprising a micrometric Si based active material having a particle size distribution with 1 μm<D50<15 μm and with 1 μm<D80<15 μm, a polymeric binder material having carboxyl functional groups and a conductive agent, wherein at least part of a surface of the Si based active material comprises a Si—OCO—R group, Si being part of the active material, and R being a polymeric chain of the binder material, and
assembling the current collector, the separator, the electrolyte, the positive electrode and the negative electrode in the battery container to prepare the rechargeable battery.

2. The process according to claim 1 , wherein the polymeric binder material comprises a compound with carboxyl functional groups and is insoluble in a carbonate or ester based solvent.

3. The process according to claim 1 , wherein the Si based active material comprises one or more of the following:
pure Si,
silicon having a SiO x surface layer, with 0<x<2, the surface layer having an average thickness between 0.5 nm and 10 nm,
a compound having the formula SiO x .(M a O b ) y , with 0<x<1 and 0≦y<1, wherein a and b are selected to provide electro neutrality, and wherein M is selected from one or more of the group consisting of Ca, Mg, Li, Al, and Zr, and
SiO.

4. The process according to claim 1 , wherein the negative electrode further comprises one or both of micrometric graphite and a nanometric Si compound, the nanometric Si compound having a particle size distribution with 50 nm<D80<200 nm.

5. The process according to claim 1 , wherein the conductive agent comprises a carbon powder.

6. The process according to claim 1 , wherein the step of providing the negative electrode comprises:
providing the micrometric Si based active material,
providing the polymeric binder material,
providing the conductive agent, and
mixing the Si based active material, the polymeric binder material and the conductive agent in a buffered slurry solution at a pH between 2.5 and 3.5, whereby at least part of the surface of the Si based active material is covered by the Si—OCO—R group, Si being part of the active material, and R being the polymeric chain of the binder material,
tape casting the slurry on a copper foil, and
drying the tape in vacuum.

7. The process according to claim 6 , wherein the buffered slurry solution comprises citric acid and KOH, and is at pH 3.

Assignees

• Delpuech Nathalie
• Mazouzi Driss
• Lestriez Bernard
• Guyomard Dominique
• Roue Lionel
• Umicore Nv
• Centre Nat Rech Scient
• Inst Nat De La Rech Scient
• Umicore Korea Ltd

Inventors

• Delpuech Nathalie
• Mazouzi Driss
• Lestriez Bernard
• Guyomard Dominique
• Roue Lionel

Classifications

• H01M4/587

  for inserting or intercalating light metals · CPC title

• H01M4/386

  Silicon or alloys based on silicon · CPC title

• H01M10/0567

  characterised by the additives · CPC title

• H01M2300/0025

  Organic electrolyte · CPC title

• H01M4/485

  of mixed oxides or hydroxides for inserting or intercalating light metals, e.g. LiTi2O4 or LiTi2OxFy (H01M4/505, H01M4/525 take precedence) · CPC title