Positively Charged Silicon for Lithium-Ion Batteries

Patent metadata

Field	Value
Publication number	US-2017244101-A1
Application number	US-201715454142-A
Country	US
Kind code	A1
Filing date	Mar 9, 2017
Priority date	Dec 14, 2011
Publication date	Aug 24, 2017
Grant date	—

Abstract

This invention relates to a negative electrode material for lithium-ion batteries comprising silicon and having a chemically treated or coated surface influencing the zeta potential of the surface. The active material consists of particles or particles and wires comprising a core comprising silicon, wherein the particles have a positive zeta potential in an interval between pH 3.5 and 9.5, and preferably between pH 4 and 9.5. The core is either chemically treated with an amino-functional metal oxide, or the core is at least partly covered with O y SiH x groups, with 1<x<3, 1≦y≦3, and x>y, or is covered by adsorbed inorganic nanoparticles or cationic multivalent metal ions or oxides.

First claim

1 - 38 . (canceled)

39 . A negative electrode material for a lithium rechargeable battery, the material comprising a core comprising silicon, wherein the surface of the core carries O y SiH x groups, with 1<x<3, 1≦y≦3, and x>y, and wherein the material has a positive zeta potential in an interval between pH 3.5 and 9.5.

40 . A negative electrode material for a lithium rechargeable battery, the material comprising a core comprising silicon, wherein the surface of the core is at least partly covered by a coating comprising inorganic nanoparticles, and wherein the material has a positive zeta potential in an interval between pH 3.5 and 9.5.

41 . The negative electrode material of claim 40 , wherein the inorganic nanoparticles comprise an aluminum compound, a zinc compound or an antimony compound.

42 . The negative electrode material of claim 41 , wherein the aluminum compound is either aluminum or Al 2 O 3 , the zinc compound is either zinc or zinc oxide, and the antimony compound is either antimony or antimony oxide.

43 . The negative electrode material of claim 40 , wherein the nanoparticles form a first coating layer on the core, the first coating layer having a thickness of less than 10 nm.

44 . The negative electrode material of claim 43 , wherein the particles further comprise a second coating layer located between the core and the nanoparticles, the second coating layer comprising either carbon or aluminum.

45 . The negative electrode material of claim 43 , wherein the first coating layer has a thickness between 1 and 5 nm.

46 . The negative electrode material of claim 43 , wherein the first coating layer is either conformal or porous.

47 . The negative electrode material of claim 44 , wherein either one or both of the first and second coating layer is electrochemically active.

48 . The negative electrode material of claim 40 , wherein the nanoparticles comprise a precursor material susceptible of being converted to aluminum, zinc or antimony by reduction.

49 . A negative electrode material for a lithium rechargeable battery, the material comprising a core comprising silicon, wherein the surface of the core is at least partly covered by adsorbed cationic multivalent metal ions, and wherein the material has a positive zeta potential in an interval between pH 3.5 and 9.5.

50 . The negative electrode material of claim 49 , wherein the metal ions are selected from the group consisting of Al-, Sb-, Fe-, Ti- and Zn-ions and combinations thereof.

51 . A negative electrode material for a lithium rechargeable battery, the material comprising a core comprising silicon, wherein the surface of the core is at least partly covered by silanol groups covalently bound to amino-functional metal compounds, wherein the metal compound is selected from the group consisting of Si, Al and Ti and combinations thereof, and wherein the material has a positive zeta potential in an interval between pH 3.5 and 9.5.

52 . A negative electrode material for a lithium rechargeable battery, the material comprising a core comprising silicon, wherein the surface of the core is at least partly covered by adsorbed nanoparticles of cationic multivalent metal oxides, and wherein the material has a positive zeta potential in an interval between pH 3.5 and 9.5.

53 . The negative electrode material of claim 52 , wherein the metal oxides are selected from the group consisting of Al-oxide, Ca-oxide, Mg-oxide, Pb-oxide, Sb-oxide, Fe-oxide, Ti-oxide, Zn-oxide and In-hydroxide and combinations thereof.

54 . The negative electrode material of claim 40 , wherein the material has a positive zeta potential in an interval between pH 4 and 9.5.

55 . The negative electrode material of claim 40 , wherein the material has a point of zero-charge at pH 4 or higher.

56 . The negative electrode material of claim 40 , comprising either particles or a mixture of particles and wires.

57 . The negative electrode material of claim 56 , wherein both the particles and the wires are nano-sized, and wherein the average particle size of the particles is at least 5 times the average width of the wires.

58 . The negative electrode material of claim 40 , wherein the core has an average particle size between 20 nm and 200 nm and comprises either
pure silicon; or a silicon monoxide powder, which comprises a mixture at nanometric scale of Si and SiO 2 ; or 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; or a homogeneous mixture of silicon- and metal-oxides, 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 electroneutrality, and wherein M is selected from the group consisting of Ca, Mg, Li, Al, and Zr; or an alloy Si—X, wherein X is either one or more metals selected from the group consisting of Sn, Ti, Fe, Ni, Cu, Co and Al.

59 . The negative electrode material of claim 40 , wherein the material has a BET value between 1 and 60 m 2 /g.

60 . A process for preparing the negative electrode material according to claim 49 , comprising:
providing a nanosized silicon material; dispersing the silicon material in water; providing a quantity of cationic multivalent metal ions in the dispersion, adjusting the pH of the dispersion to a value between 2 and 3.5, and thereafter adjusting the pH of the dispersion to a value between pH 3.5 and 4, determining the zeta potential of the dispersion, and, if the zeta potential is negative, further adjusting the pH of the dispersion to a value 0.5 above the previous pH value, and determining the zeta potential of the solution, and repeating the adjustment step until a positive zeta potential is measured.

61 . The process according to claim 60 , wherein the step of adjusting the pH of the dispersion to a value between 2 and 3.5 is performed by addition of HCl, and wherein both the step of adjusting the pH of the dispersion to a value between 3.5 and 4, and, if applicable, the steps of further adjusting the pH of the dispersion to a value 0.5 above the previous pH value, are performed by addition of NaOH.

62 . A process for preparing the negative electrode material according to claim 40 , comprising:
providing a nanosized silicon material, and subjecting the silicon material to an atomic layer deposition process in a reaction chamber under a vacuum of at least 1 mbar and at a temperature between 50 and 500° C., making use of a gaseous organo-aluminum, organo-zinc or organo-antimony stream and water vapour, until a layer with a thickness between 2 and 10 nm is formed on the surface of the silicon material.

63 . The process according to claim 62 , wherein the organo-aluminum compound is trimethyl aluminum.

64 . A process for preparing the negative electrode material according to claim 49 , comprising:
providing a nanosized silicon material, and dispersing the silicon material in water, providing a quantity of cationic multivalent metal ions in the dispersion, mixing the dispersion whereby the silicon material is at least partly covered by adsorbed cationic multivalent metal ions, and drying the metal ion-silicon mixture.

65 . The process according to claim 64 , further comprising:
redispersing the dry metal ion-silicon mixture in water, and acidifying the dispersion to a pH between 2 and 6.

66 . The

Assignees

• Umicore Nv

Inventors

• Put Stijn
• Gilleir Jan
• Driesen Kris
• Bridel Jean-Sébastien
• Marx Nicolas
• Longrie Delphine
• Goia Dan V
• Njagi John I

Classifications

• H01M4/366 Primary

  as layered products · CPC title

• H01M10/0525

  Rocking-chair batteries, i.e. batteries with lithium insertion or intercalation in both electrodes; Lithium-ion batteries · CPC title

• H01M4/483

  for non-aqueous cells (H01M4/485 takes precedence) · CPC title

• H01M2004/027

  Negative electrodes · CPC title

• H01M4/386

  Silicon or alloys based on silicon · CPC title