When spinel-type lithiated cobalt oxide is employed for a cathode active material for a lithium ion battery, a sufficient discharge capacity is not always obtained. Thus, spinel-type lithiated cobalt oxide is doped with at least chromium, and specifically, a cathode active material for a lithium ion battery includes a spinel-type crystal phase including lithium, cobalt, chromium and oxygen, and the cathode active material has a composition represented by LiCo.sub.xCr.sub.yM.sub.zO.sub.2 where M is at least one selected from Al and Mn, and 0.85x<1, 0<y0.15, 0z, and 0.85<x+y+z1.2.

A method for forming a crystalline material having an anisotropic, quasi-one-dimensional crystal structure is disclosed. In various embodiments, the method includes: mixing a plurality of precursor materials together to form a combined precursor material, the plurality of precursor materials including a transition-metal ion or a main group ion and at least one of an alkaline earth ion or an alkali metal ion; and reacting the combined precursor material to obtain the crystalline material, the crystalline material having a formula ABX3, wherein A is the at least one of the alkaline earth ion or the alkali metal ion and B is the transition-metal ion surrounded by six anions (X), and wherein the quasi-one-dimensional anisotropic crystal provides a birefringence of at least 0.03, defined as the absolute difference in the real part of the complex-refractive-index values along different crystal axes, in at least a portion of one or N both of the visible-wave spectrum or the infrared spectrum.

The present invention is a method of producing silicon compound coated oxide particles in which at least a part of a surface of a metal oxide particle is coated with a silicon compound, wherein wettability and color characteristics are controlled by controlling a ratio of SiOH bonds contained in the silicon compound coated oxide particles. By the present invention, silicon compound coated oxide particles having controlled wettability such as hydrophilicity, water repellency or oil repellency, and controlled color characteristics of either reflectivity, molar absorption coefficient or transmittance can be provided.

A positive electrode active material has a small difference in a crystal structure between the charged state and the discharged state. For example, the crystal structure and volume of the positive electrode active material, which has a layered rock-salt crystal structure in the discharged state and a pseudo-spinel crystal structure in the charged state at a high voltage of approximately 4.6 V, are less likely to be changed by charging and discharging as compared with those of a known positive electrode active material. In order to form the positive electrode active material having the pseudo-spinel crystal structure in the charged state, it is preferable that a halogen source such as a fluorine and a magnesium source be mixed with particles of a composite oxide containing lithium, a transition metal, and oxygen, which is synthesized in advance, and then the mixture be heated at an appropriate temperature for an appropriate time.

Disclosed are a precursor for preparation of a lithium composite transition metal oxide, a method for preparing the same and a lithium composite transition metal oxide obtained from the same. More particularly, the transition metal precursor which has a composition represented by Formula 1 below and is prepared in an aqueous transition metal solution, mixed with a transition metal-containing salt, including an alkaline material, the method for preparing the same and the lithium composite transition metal oxide obtained from the same are disclosed.
Mn.sub.aM.sub.b(OH.sub.1-x).sub.2-yA.sub.y(1) wherein M is at least one selected form the group consisting of Ni, Ti, Co, Al, Cu, Fe, Mg, B, Cr, Zr, Zn and Period II transition metals; A is at least one selected form the group consisting of anions of PO.sub.4, BO.sub.3, CO.sub.3, F and NO.sub.3, and 0.5a1.0; 0b0.5; a+b=1; 0<x<1.0; and 0y0.02.

Provided is a battery including: a positive electrode containing a positive electrode active material; a negative electrode; and an electrolyte solution containing a nonaqueous solvent. The positive electrode active material contains a compound represented by composition formula (1) below and having a crystal structure belonging to space group FM3-M: Li.sub.xMe.sub.yO.sub.F.sub.. (1) Here, Me is one or two or more elements selected from the group consisting of Mn, Co, Ni, Fe, Al, B, Ce, Si, Zr, Nb, Pr, Ti, W, Ge, Mo, Sn, Bi, Cu, Mg, Ca, Ba, Sr, Y, Zn, Ga, Er, La, Sm, Yb, V, and C. x, y, , and satisfy the following conditions: 1.7x2.2, 0.8y1.3, 12.5, and 0.52, respectively. The nonaqueous solvent includes at least one solvent selected from hydrofluoroethers, phosphazenes, phosphates, and perfluoropolyethers.

A positive electrode active material has a small difference in a crystal structure between the charged state and the discharged state. For example, the crystal structure and volume of the positive electrode active material, which has a layered rock-salt crystal structure in the discharged state and a pseudo-spinel crystal structure in the charged state at a high voltage of approximately 4.6 V, are less likely to be changed by charging and discharging as compared with those of a known positive electrode active material. In order to form the positive electrode active material having the pseudo-spinel crystal structure in the charged state, it is preferable that a halogen source such as a fluorine and a magnesium source be mixed with particles of a composite oxide containing lithium, a transition metal, and oxygen, which is synthesized in advance, and then the mixture be heated at an appropriate temperature for an appropriate time.

A battery includes a positive electrode including a positive electrode active material, a negative electrode, and an electrolytic solution including a lithium hexafluorophosphate and an additive. The positive electrode active material includes a compound having a crystal structure belonging to a space group FM3-M and represented by Compositional Formula (1): Li.sub.xMe.sub.yO.sub.F.sub.. The additive is at least one selected from the group consisting of difluorophosphates, tetrafluoroborates, bis(oxalate)borate salts, bis(trifluoromethanesulfonyl)imide salts, and bis(fluorosulfonyl)imide salts.

A positive-electrode active material containing a compound that has a crystal structure belonging to the space group FM-3M and is represented by the composition formula (1):

Li.sub.xMe.sub.yO.sub.F.sub.(1)

wherein Me denotes one or two or more elements selected from the group consisting of Mn, Co, Ni, Fe, and Al, and the following conditions are satisfied.

1.3x2.2,

0.8y1.3,

12.93,

0.072.

A positive-electrode active material contains a compound that has a crystal structure belonging to a space group FM3-M and contains is represented by the composition formula (1) and an insulating compound,

Li.sub.xMe.sub.yO.sub.F.sub.(1) wherein Me denotes one or two or more elements selected from the group consisting of Mn, Co, Ni, Fe, Al, B, Ce, Si, Zr, Nb, Pr, Ti, W, Ge, Mo, Sn, Bi, Cu, Mg, Ca, Ba, Sr, Y, Zn, Ga, Er, La, Sm, Yb, V, and Cr, and the following conditions are satisfied.

1.7x2.2

0.8y1.3

12.5

0.52