A positive electrode active material is constituted by lithium transition metal-containing composite oxide particles having a layered rock salt type crystal structure and are composed of secondary particles each formed of an aggregation of primary particles. The secondary particles have a d50 of 3.0 to 7.0 μm, a BET specific surface area of 1.8 to 5.5 m.sup.2/g, a pore peak diameter of 0.01 to 0.30 μm, and a log differential pore volume [dV/d(log D)] of 0.2 to 0.6 ml/g within a range of the pore peak diameter. In each of a plurality of primary particles having a primary particle size of 0.1 to 1.0 μm, a coefficient of variation of the concentration of an additive element M is 1.5 or less.

Each of the Ni-containing lithium-based complex oxide A and the Ni-containing lithium-based complex oxide B contains Ni in an amount of 55 mol % or more relative to the total number of moles of metal elements excluding Li, the Ni-containing lithium-based complex oxide A has an average primary particle diameter of 2 μm or more, an average secondary particle diameter of 2 to 6 μm, a particle fracture load of 5 to 35 mN and a BET specific surface area of 0.5 m2/g to 1.0 m2/g, and the Ni-containing lithium-based complex oxide B has an average primary particle diameter of 1 μm or less, an average secondary particle diameter of 10 to 20 μm, a particle fracture load of 10 to 35 mN and a BET specific surface area of 0.1 m2/g to 1.0 m2/g.

The invention relates to active electrode materials and to methods for the manufacture of active electrode materials. Such materials are of interest as active electrode materials in lithium-ion or sodium-ion batteries. The invention provides an active electrode material expressed by the general formula [M][Nb].sub.y[O].sub.z; wherein the active electrode material is oxygen deficient; wherein M consists of one of Mg, Cr, W, Mo, Cu, Ga, Ge, Ca, K, Ni, Co, Al, Sn, Mn, Ce, Sb, Y, La, Hf, Ta, Zn, In, or Cd; y satisfies 0.5≤y≤49; and z satisfies 4≤z≤124.

A positive electrode active material having a core/shell structure, which includes a sulfur-carbon composite containing thermally expanded-reduced graphene oxide, a carbon material as a core, and carbon nanotubes as a shell. A method for preparing a positive electrode active material having a core/shell structure for a lithium secondary battery, including the steps of thermally expanding graphene oxide by heat treatment at a temperature in a range of 300° C. to 500° C. to prepare a thermally-expanded graphene oxide. Then, reducing the thermally-expanded graphene oxide by heat treatment at a temperature in a range of 700° C. to 1200° C. to prepare a thermally expanded-reduced graphene oxide. Next, mixing the thermally expanded-reduced graphene oxide and sulfur to prepare a sulfur-carbon composite. Last, mixing the sulfur-carbon composite and carbon nanotubes to form carbon nanotubes on a surface of the sulfur-carbon composite.

Provided is a hydrophobic silica aerogel blanket comprising holes, so that the diffusion of a surface modifier is facilitated in a blanket during a surface modification process to improve the efficiency of surface modification. Accordingly, the hydrophobic silica aerogel has not only excellent physical properties such as specific surface area and thermal conductivity, but also a controlled degree of hydrophobicity, and thus, can have high hydrophobicity.

A zirconia powder in which when a stabilizer is Y.sub.2O.sub.3, a content thereof is 1.4 mol % or more and less than 2.0 mol %; when the stabilizer is Er.sub.2O.sub.3, a content thereof is 1.4 mol % or more and 1.8 mol % or less; when the stabilizer is Yb.sub.2O.sub.3, a content thereof is 1.4 mol % or more and 1.8 mol % or less; and when the stabilizer is CaO, a content thereof is 3.5 mol % or more and 4.5 mol % or less; and in a range of 10 nm or more and 200 nm or less in a pore distribution, a peak top diameter of a pore volume distribution is 20 nm or more and 120 nm or less, a pore volume is 0.2 ml/g or more and less than 0.5 ml/g, and a pore distribution width is 30 nm or more and 170 nm or less.

A zirconia powder containing a stabilizer, and having a specific surface area of 20 m.sup.2/g or more and 60 m.sup.2/g or less and a particle diameter D.sub.50 of 0.1 μm or more and 0.7 μm or less, in which in a range of 10 nm or more and 200 nm or less in a pore distribution based on a mercury intrusion method, a peak top diameter in a pore volume distribution is 20 nm or more and 85 nm or less, a pore volume is 0.2 ml/g or more and less than 0.5 ml/g, and a pore distribution width is 40 nm or more and 105 nm or less.

A method can include milling a plurality of silicon particles to form a plurality of milled silicon particles. The milled silicon particles can optionally include collecting the milled silicon particles, powdering the milled silicon particles, and milling the milled silicon particles a second time.

According to an embodiment, there is provided an electrode including an active material-containing layer. A logarithmic differential pore volume distribution curve of the active material-containing layer by a mercury intrusion method includes first and second peaks. The first peak is a local maximum value in a range where a pore size is from 0.1 μm or more to 0.5 μm or less. The second peak is a local maximum value in a range where the pore size is from 0.5 μm or more to 1.0 μm or less. An intensity A1 of the first peak and an intensity A2 of the second peak satisfy 0.1≤A2/A1≤0.3. A density of the active material-containing layer is from 2.9 g/cm.sup.3 or more to 3.3 g/cm.sup.3 or less.

Disclosed herein are methods for the preparation of porous metal oxide materials, including metal oxide xerogels and metal oxide aerogels. Methods for preparing porous metal oxide materials can comprise (i) reacting a metal alkoxide with water in the presence of a catalyst system to form a partially hydrolyzed sol, (ii) contacting the partially hydrolyzed sol with a base catalyst and a non-aqueous solvent to form a precursor gel; and (iii) drying the precursor gel to form the porous metal oxide material. The catalyst system employed in step (i) comprises a combination of a weak acid and a strong acid.