Coated metal oxide particles with low dissolution rate, methods for preparing same and use thereof in electrochemical systems

Patent metadata

Field	Value
Publication number	US-2017346096-A1
Application number	US-201715675184-A
Country	US
Kind code	A1
Filing date	Aug 11, 2017
Priority date	Jan 25, 2006
Publication date	Nov 30, 2017
Grant date	—

Abstract

Particles including a core and a coat covering at least part of the core surface. The core has more than 50% of an acidic metal oxide and the core coating is based on a polymer, preferably based on a solid polymer with high electrochemical stability. The particle has a solubility rate (ds), in fixed time, of the metal oxide migrating towards the electrolyte, per cycle, which is less than 5 per 10000. The particles are obtained by mixing the polymer and a metal oxide, via dry process with addition of solvent. The electrodes constituting an electrode substrate at least partly coated with a mixture consisting of at least 40 of those particles have remarkable electrochemical properties, in particular regarding the lifetime of batteries in which they are incorporated.

First claim

1 . A particle comprising a core and a coating that covers at least part, preferably at least 80%, even more preferentially at least 90% and most advantageously 100% of the surface of said core, said particle being characterized in that:
said core is preferably composed to at least 90% and even more preferentially to at least 94% by weight of an acidic metal oxide, with a pH preferably of less than 6.5, and even more preferentially with a pH of between 3 and 6; the coating of the core being based on a polymer, preferably based on a salified polymer, whose electrochemical stability is greater than or equal to 3.7 volts; the mean thickness of the coating is preferentially between 500 nanometers and 2 micrometers and the coated core has a mean size d 50 preferably of between 500 nanometers and 40 micrometers, and even more preferentially this size is between 2 and 20 micrometers; and the degree of solubility (ds), for a given time, of the metal oxide migrating toward the electrolyte, per cycle, is less than 5 per 10 000, and this degree is preferably between 2 and 4.5 per 10 000.

2 . A process for reducing the solubility of metal oxides in electrochemical systems, which consists in increasing the pH of the oxide, preferentially by selecting the nature and the amount of the carbon mixed with the oxide particles, more particularly by coating the oxide particles with a polymer, based on PEO, polyacrylonitrile, PMMA and/or PVC dissolved in a solvent (acetonitrile, water, acetone, methanol, etc.) and then by drying the composition and carbonizing it at a temperature of about 600-700° C., under an inert atmosphere for 8-12 hours; the amount and type of the polymer used being linked to the residual content of carbon present at the surface of the oxide particles, and the mixing of the oxide and the polymer solution possibly being advantageously performed with a jar mill, a bar mill or a paint mixer.

Assignees

• Hydro Quebec

Inventors

• Charest Patrick
• Perrier Michel
• Dontigny Martin
• Petitclerc Michel
• Guerfi Abdelbast
• Zaghib Karim

Classifications

• H01M4/136

  Electrodes based on inorganic compounds other than oxides or hydroxides, e.g. sulfides, selenides, tellurides, halogenides or LiCoFy · CPC title

• H01M4/131

  Electrodes based on mixed oxides or hydroxides, or on mixtures of oxides or hydroxides, e.g. LiCoOx · CPC title

• H01M10/0565

  Polymeric materials, e.g. gel-type or solid-type · CPC title

• H01M10/052

  Li-accumulators · CPC title

• H01M4/625

  Carbon or graphite · CPC title