The present invention relates to a positive electrode active material and a lithium secondary battery including the same, and more particularly, to a positive electrode active material including a lithium composite oxide containing at least nickel and cobalt, wherein since the cobalt in the lithium composite oxide has a concentration gradient having at least different slopes from a surface portion toward a central portion, it is possible to improve the stability of particles not only in a surface portion of the lithium composite oxide but also in a central portion thereof, a positive electrode including the positive electrode active material, and a lithium secondary battery using the negative electrode.

The present invention relates to a positive electrode active material and a lithium secondary battery including the same, and more particularly, to a bimodal-type positive electrode active material including a first lithium composite oxide as a small particle and a second lithium composite oxide as a large particle, wherein the positive electrode active material may uniformly improve the particle stability of the small particle and the large particle by controlling a slope of a concentration gradient in which cobalt in the small particle and the large particle decreases from a surface portion toward a central portion, a positive electrode including the positive electrode active material, and a lithium secondary battery using the positive electrode.

This positive electrode active material for nonaqueous electrolyte secondary batteries contains: a lithium transition metal composite oxide having secondary particles, each of which is formed of aggregated primary particles; and a surface modification compound which is present on at least the surfaces of the secondary particles, while containing at least one of Ca and Sr. The lithium transition metal composite oxide contains 70% by mole or more of Ni relative to the total number of moles of the metal elements excluding Li; and the total amount of Ca and Sr in the surface modification compound is 0.5% by mole or less relative to the total number of moles of the metal elements excluding Li in the lithium transition metal composite oxide.

The present invention pertains to: a positive electrode active material precursor containing first secondary particle composed of an aggregate of a plurality of first primary particles, the positive electrode active material precursor including a first center portion represented by chemical formula 1 and a first surface portion represented by chemical formula 2, wherein the thickness of the first surface portion is 2-20% of the average radius of the positive electrode active material precursor; and a positive electrode active material containing the positive electrode active material precursor.

A titanium sulfide (TiS) nanomaterial and a composite material thereof for wave absorption are disclosed. The TiS nanomaterial is in a form of dispersed micro-particles which are bulks formed by stacking two-dimensional nano-sheets. The TiS nanomaterial is a bulk formed by stacking two-dimensional nano-sheets, thereby having a laminated structure that improves the wave absorption effect. In addition, experimental results demonstrate that the TiS nanomaterial with a dose of 40 wt% has the most excellent wave absorption performance, with a minimum reflection loss up to -47.4 dB, an effective absorption bandwidth of 5.9 GHz and an absorption peak frequency of 6.8 GHz, which are superior to those of existing two-dimensional bulk materials. One of reasons for the excellent wave absorption performance of the TiS nanomaterial may be because the laminated micro-morphology of TiS results in the electromagnetic wave refraction loss.

A method of recovering an active material from a positive electrode scrap and reusing the active material is provided. The method of reusing a positive electrode active material includes (a) thermally treating a positive electrode scrap comprising an active material layer on a current collector in air for thermal decomposition of a binder and a conductive material in the active material layer, to separate the current collector from the active material layer, and collecting an active material in the active material layer; (b) washing the active material collected from the step (a) with a cleaning solution; and (c) annealing the active material washed from the step (b) with an addition of a lithium precursor to obtain a reusable active material, wherein a molar ratio of lithium to other metals in the active material after the thermal treatment step (a) or a molar ratio of lithium to other metals in the active material after the washing step (b) has a decreased range of 20% or less when compared with a molar ratio of lithium to other metals in the positive electrode scrap before the thermal treatment step (a).

A thermal method of forming ferric oxide nano/microparticles with predominant morphology is described using different solvents. Methods of using the Fe.sub.3O.sub.4 nano/microparticles as catalysts in the reduction of nitro compounds with sodium borohydride to the corresponding amines and decomposition of ammonium salts.

A ceramic powder material containing a garnet-type compound containing Li, wherein the ceramic powder material has a pore volume of 0.4 mL/g or more and 1.0 mL/g or less.

Provided is a boron nitride agglomerate. The boron nitride agglomerate is of a multi-stage structure formed by arranging flaky hexagonal boron nitride primary particles in three-dimensional directions through adhesion of an inorganic binder. Further provided is a method for preparing the boron nitride agglomerate. The method comprises: mixing flaky hexagonal boron nitride primary particles with an inorganic binder, and controlling the mass of the inorganic binder to account for 0.02-20% of the mass of the flaky hexagonal boron nitride primary particles, so as to obtain the boron nitride agglomerate. The boron nitride agglomerate provided can be added to thermosetting resin compositions, and resin sheets, resin composite metal foil, prepregs, laminates, metal foil-covered laminates, and printed wiring boards prepared using the same have higher boron nitride addition, high thermal conductivity, and high peel strength.

A nickel-based active material for a lithium secondary battery, a method of preparing the nickel-based active material, and a lithium secondary battery including a positive electrode including the nickel-based active material, the nickel-based active material comprising a secondary particle having an outer portion with a radially arranged structure and an inner portion with an irregular porous structure, wherein the inner portion of the secondary particle has a larger pore size than the outer portion of the secondary particle.