Coated lithium-nickel composite oxide particles and method for producing coated lithium-nickel composite oxide particles
Provided are excellent coated lithium-nickel composite oxide particles which are capable of suppressing the occurrence of impurities produced by absorbing water and carbonic acid gas as a result of the high environmental stability thereof, have strong adhesion properties, do not result in easy coating layer detachment, and also exhibit lithium ion conductivity. The surfaces of the lithium-nickel composite oxide particles are coated with a polymer or copolymer comprising one or more types selected from a group consisting of a modified polyolefin resin, a polyester resin, a polyphenol resin, a polyurethane resin, an epoxy resin, a silane-modified polyether resin, a silane-modified polyester resin, a silane-modified polyphenol resin, a silane-modified polyurethane resin, a silane-modified epoxy resin, and a silane-modified polyamide resin. As a result, the coated lithium-nickel composite oxide particles exhibit conductivity, and said compound is capable of suppressing the transmission of water and carbonic acid gas. Consequently, it is possible to provide coated lithium-nickel composite oxide particles for use in a lithium-ion battery positive electrode active material which is excellent for use in a lithium-ion battery.
1. Coated lithium-nickel composite oxide particles for a lithium-ion battery positive-electrode active substance, comprising:
nickel-based lithium-nickel composite oxide particles; and
coated films of a polymer or copolymer coated on surfaces of the nickel-based lithium-nickel composite oxide particles,
wherein the polymer or copolymer includes at least one kind selected from the group consisting of a silane-modified polyether resin, a silane-modified polyester resin, a silane-modified polyphenol resin, a silane-modified polyurethane resin, a silane-modified epoxy resin, and a silane-modified polyamide resin,
wherein a coating amount of the polymer or copolymer is 0.05 to 5.0% by mass based on 100% by mass of the lithium-nickel composite oxide particles,
the silane-modified epoxy resin is produced by modifying part or the entire part of the hydroxyl groups of a bisphenol-type epoxy resin with a hydrolyzable alkoxysilane, and
the lithium-nickel composite oxide is represented by the following Formula (1),
Li x Ni( 1-y-z )M y N z O 2 (1)
wherein x is a value of from 0.80 to 1.10, y is a value of from 0.01 to 0.20, z is a value of from 0.01 to 0.15, and 1-y-z is a value exceeding 0.65, and M represents at least one element selected from Co or Mn, and N represents at least one element selected from Al, In or Sn.
2. The coated lithium-nickel composite oxide particles according to claim 1 , wherein the coated lithium-nickel composite oxide particles are spherical particles having an average particle diameter of 5 to 20 μm.
3. The coated lithium-nickel composite oxide particles according to claim 1 , wherein
the polymer or copolymer is a polymer or copolymer including at least one kind selected from the group consisting of a silane-modified polyether resin, a silane-modified polyester resin, a silane-modified polyphenol resin, a silane-modified polyurethane resin, and a silane-modified polyamide resin.
4. A method for producing the coated lithium-nickel composite oxide particles according to claim 1 , comprising:
preparing a solution of a resin for coating by dissolving a polymer or copolymer including at least one kind selected from the group consisting of a silane-modified polyether resin, a silane-modified polyester resin, a silane-modified polyphenol resin, a silane-modified polyurethane resin, a silane-modified epoxy resin, and a silane-modified polyamide resin in a good solvent dissolving the polymer or copolymer;
adding a poor solvent not dissolving the resin for coating and having an evaporation rate lower than that of the good solvent, into the solution of a resin for coating;
adding the lithium-nickel composite oxide particles into the solution of a resin for coating to prepare a slurry; and
removing the good solvent and the poor solvent sequentially from the slurry.