Positive electrode active substance for secondary cell and method for producing same

Patent metadata

Field	Value
Publication number	US-2018053929-A1
Application number	US-201515556936-A
Country	US
Kind code	A1
Filing date	Sep 17, 2015
Priority date	Mar 9, 2015
Publication date	Feb 22, 2018
Grant date	—

Abstract

A positive electrode active substance for a secondary cell, where the positive electrode active substance is capable of suppressing adsorption of water effectively in order to obtain a high-performance lithium ion secondary cell or sodium ion secondary cell. The positive electrode active substance contains 0.3 to 5 mass % of graphite, 0.1 to 4 mass % of carbon obtained by carbonizing a water-soluble carbon material, or 0.1 to 5 mass % of a metal fluoride is supported on a composite containing a compound which contains at least iron or manganese, where the compound is represented by formula (A) LiFe a Mn b M c PO 4 , formula (B) Li 2 Fe d Mn e N f SiO 4 , or formula (C) NaFe g Mn h Q i PO 4 , and carbon obtained by carbonizing a cellulose nanofiber.

First claim

1 . A positive electrode active substance, comprising 0.3 to 5 mass % of graphite, 0.1 to 4 mass % of carbon obtained by carbonizing a water-soluble carbon material, or 0.1 to 5 mass % of a metal fluoride supported on a composite comprising:
a compound comprising at least iron or manganese, the compound being represented by formula (A), (B), or (C):
LiFe a Mn b M 1 c PO 4   (A)

wherein M 1 represents Mg, Ca, Sr, Y, Zr, Mo, Ba, Pb, Bi, La, Ce, Nd, or Gd, and a, b, and c each represent a number satisfying 0≦a≦1, 0≦b≦1, 0≦c≦0.2, 2a+2b+(valence of M 1 )×c=2, and a+b≠0;
Li 2 Fe d Mn e M 2 f SiO 4   (B)

wherein M 2 represents Ni, Co, Al, Zn, V, or Zr, and d, e, and f each represent a number satisfying 0≦d≦1, 0≦e≦1, 0≦f<1, 2d+2e+(valence of M 2 )×f=2, and d+e≠0; and
NaFe g Mn h Q i PO 4   (C)

wherein Q represents Mg, Ca, Co, Sr, Y, Zr, Mo, Ba, Pb, Bi, La, Ce, Nd, or Gd, and g, h, and i each represent a number satisfying 0≦g≦1, 0≦h≦1, 0≦i<1, 2g+2h+(valence of Q)×i=2, and g+h≠0; and
carbon obtained by carbonizing a cellulose nanofiber.

2 . The positive electrode active substance according to claim 1 , wherein an amount of the cellulose nanofiber expressed in terms of carbon atoms is 0.5 to 15 mass %.

3 . The positive electrode active substance according to claim 1 , obtained by adding the graphite to the composite comprising the compound and the cellulose nanofiber and conducting mixing treatment for 6 to 90 minutes while applying compressive force and shear force, wherein
a mass ratio of an amount of the graphite added to an amount of the cellulose nanofiber expressed in terms of carbon atoms, (graphite/cellulose nanofiber), is 0.08 to 6.

4 . The positive electrode active substance according to claim 1 , wherein the water-soluble carbon material is supported on the composite as carbon obtained by subjecting the water-soluble carbon material and the composite comprising the compound and the cellulose nanofiber to wet mixing and then carbonizing the resulting mixture.

5 . The positive electrode active substance according to claim 1 , wherein the water-soluble carbon material is at least one selected from the group consisting of saccharides, polyols, polyethers, and organic acids.

6 . The positive electrode active substance according to claim 1 , wherein the metal fluoride is supported on the composite by subjecting the composite comprising the compound and the cellulose nanofiber and a precursor of the metal fluoride to wet mixing.

7 . The positive electrode active substance according to claim 1 , wherein:
a metal of the metal fluoride is selected from the group consisting of lithium, sodium, magnesium, calcium, and aluminum; and a precursor of the metal fluoride comprises: a fluorine compound selected from the group consisting of ammonium fluoride, hydrofluoric acid, and hypofluorous acid; as well as a metal compound selected from the group consisting of metal acetates, metal nitrates, metal lactates, metal oxalates, metal hydroxides, metal ethoxides, metal isopropoxides, and metal butoxides.

8 . The positive electrode active substance according to claim 1 , wherein the composite comprising the compound and the cellulose nanofiber is obtained by subjecting slurry comprising:
a lithium compound or a sodium compound; a phosphoric acid compound or a silicic acid compound; at least an iron compound or a manganese compound; and a cellulose nanofiber to hydrothermal reaction.

9 . A method for producing a positive electrode active substance, the positive electrode active substance comprising 0.3 to 5 mass % of graphite supported on a composite comprising:
a compound comprising at least iron or manganese, the compound being represented by formula (A), (B), or (C):
LiFe a Mn b M 1 c PO 4   (A)

wherein M 1 represents Mg, Ca, Sr, Y, Zr, Mo, Ba, Pb, Bi, La, Ce, Nd, or Gd, and a, b, and c each represent a number satisfying 0≦a≦1, 0≦b≦1, 0≦c≦0.2, 2a+2b+(valence of M 1 )×c=2, and a+b≠0;
Li 2 Fe d Mn e M 2 f SiO 4   (B)

wherein M 2 represents Ni, Co, Al, Zn, V, or Zr, and d, e, and f each represent a number satisfying 0≦d≦1, 0≦e≦1, 0≦f<1, 2d+2e+(valence of M 2 )×f=2, and d+e≠0; and
NaFe g Mn h Q i PO 4   (C)

wherein Q represents Mg, Ca, Co, Sr, Y, Zr, Mo, Ba, Pb, Bi, La, Ce, Nd, or Gd, and g, h, and i each represent a number satisfying 0≦g≦1, 0≦h≦1, 0≦i<1, 2g+2h+(valence of Q)×i=2, and g+h≠0; and
carbon obtained by carbonizing a cellulose nanofiber, the method comprising: (I-1) mixing a phosphoric acid compound or a silicic acid compound with a mixture (X-1) comprising: a lithium compound or a sodium compound; and a cellulose nanofiber, thereby obtaining a composite (X-1); (II-1) subjecting slurry (Y-1) comprising: the obtained composite (X-1); and a metal salt comprising at least an iron compound or a manganese compound to hydrothermal reaction, thereby obtaining a composite (Y-1); (III-1) adding the graphite to the obtained composite (Y-1) to conduct mixing for 6 to 90 minutes while applying compressive force and shear force, thereby obtaining a composite (Z-1); and (IV-1) pyrolyzing the obtained composite (Z-1) in a reducing atmosphere or an inert atmosphere.

10 . A method for producing a positive electrode active substance, the positive electrode active substance comprising 0.1 to 4 mass % of carbon obtained by carbonizing a water-soluble carbon material, or 0.1 to 5 mass % of a metal fluoride supported on a composite comprising:
compound comprising at least iron or manganese, the compound being represented by formula (A), (B), or (C):
LiFe a Mn b M 1 c PO 4   (A)

wherein M 1 represents Mg, Ca, Sr, Y, Zr, Mo, Ba, Pb, Bi, La, Ce, Nd, or Gd, and a, b, and c each represent a number satisfying 0≦a≦1, 0≦b≦1, 0≦c≦0.2, 2a+2b+(valence of M 1 )×c=2, and a+b≠0;
Li 2 Fe d Mn e M 2 f SiO 4   (B)

wherein M 2 represents Ni, Co, Al, Zn, V, or Zr, and d, e, and f each represent a number satisfying 0≦d≦1, 0≦e≦1, 0≦f<1, 2d+2e+(valence of M 2 )×f=2, and d+e≠0; and
NaFe g Mn h Q i PO 4   (C)

wherein Q represents Mg, Ca, Co, Sr, Y, Zr, Mo, Ba, Pb, Bi, La, Ce, Nd, or Gd, and g, h, and i each represent a number satisfying 0≦g≦1, 0≦h≦1, 0≦i<1, 2g+2h+(valence of Q)×i=2, and g+h≠0; and
carbon obtained by carbonizing a cellulose nanofiber, the method comprising: (I-2) mixing a phosphoric acid compound or a silicic acid compound with a mixture (X-2) comprising: a lithium compound or a sodium compound; and a cellulose nanofiber, thereby obtaining a composite (X-2); (II-2) subjecting slurry (Y-2) comprising: the obtained composite (X-2); and a metal salt comprising at least an iron compound or a manganese compound to hydrothermal reaction, thereby obtaining a composite (Y-2); and (III-2) adding 0.1 to 16 mass parts of a water-soluble organic compound to the obtained composite (Y-2) based on 100 mass parts of the composite (Y-2) or adding 0.1 to 40 mass parts of a precursor of the metal fluoride to the obtained composite (Y-2) based on 100 mass parts of the composite (Y-2) and conducting wet mixing, and then pyrolyzing.

Assignees

• Taiheiyo Cement Corp

Inventors

• Yamashita Hiroki
• Hatsumori Tomoki
• Nakamura Atsushi
• Ogami Takaaki

Classifications

• H01M4/587

  for inserting or intercalating light metals · CPC title

• C01P2006/40

  Electric properties · CPC title

• H01M4/136

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

• H01M4/625

  Carbon or graphite · CPC title

• H01M4/62

  Selection of inactive substances as ingredients for active masses, e.g. binders, fillers · CPC title