A method of preparing a bimodal positive electrode active material precursor and a positive electrode active material prepared from the same are disclosed herein. In some embodiments, the method includes inputting a first reaction source material including a first aqueous transition metal solution into a reactor, precipitating at pH 12 or more to induce nucleation of a first positive electrode active material precursor particle, and at less than pH 12 to induce growth of the same, inputting a second reaction source material including a second aqueous transition metal solution into the reactor containing the first positive electrode active material precursor particle, precipitating at pH 12 or more to induce the nucleation of a second positive electrode active material precursor particle, and at less than pH 12 to induce simultaneous growth of the first and second positive electrode active material precursor particles, thereby preparing a bimodal positive electrode active material precursor.

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.

There is provided a method for collecting and reusing an active material from positive electrode scrap. The method of reusing a positive electrode active material of the present disclosure 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-1) washing the active material collected from the step (a) with a lithium compound solution which is basic in an aqueous solution, and drying, (b-2) grinding the active material dried from the step (b-1), (b-3) adding a lithium compound to the active material ground from the step (b-2), and (c) annealing the active material having the lithium precursor added thereto, to obtain a reusable active material.

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).

Provided is a piezoelectric material filler including alkali niobate compound particles having a ratio (K/(Na+K)) of the number of moles of potassium to the total number of moles of sodium and potassium of 0.460 to 0.495 in terms of atoms and a ratio ((Li+Na+K)/Nb) of the total number of moles of alkali metal elements to the number of moles of niobium of 0.995 to 1.005 in terms of atoms. The present invention can provide a piezoelectric material filler having excellent piezoelectric properties, and a composite piezoelectric material including the piezoelectric material filler and a polymer matrix.

There is provided a method for collecting and reusing an active material from positive electrode scrap. The positive electrode active material reuse method of the present disclosure includes (a) thermally treating positive electrode scrap comprising a lithium cobalt oxide positive electrode 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 collected active material with a lithium compound solution which is basic in an aqueous solution and drying, and (c) annealing the washed active material with an addition of a lithium precursor to obtain a reusable active material.

A dielectric elastomer transducer according to the present invention includes a dielectric elastomer layer, and a pair of electrode layers sandwiching the dielectric elastomer layer. The electrode layers contain a binder and carbon black. The carbon black has a particle size distribution as measured by dynamic light scattering in which not less than 95% falls in a range of 0.15 to 8.0 μm. The carbon black has a particle size as measured by laser scattering ranging from 0.4 to 50 μm. The particle size distribution of the carbon black as measured by dynamic light scattering has a first peak that falls in a first range of 0.15 to 1.0 μm and a second peak that falls in a second range of 1.0 μm to 8.0 μm. This structure achieves both stretchability and electrical conductivity of the electrode layers.

This positive electrode active material for a nonaqueous electrolyte secondary battery includes a lithium transition metal composite oxide that contains at least 80 mol % of Ni with respect to the total number of moles of metal elements excluding Li. B is present at least on the surfaces of the particles of the composite oxide. When particles having a particle diameter larger than a volume-based particle diameter of 70% (D70) are defined as first particles and particles having a particle diameter smaller than a volume-based particle diameter of 30% (D30) are defined as second particles, the molar fraction of B with respect to the total number of moles of metal elements excluding Li in the second particles is higher than the molar fraction of B with respect to the total number of moles of metal elements excluding Li in the first particles.

A composite positive active material for a lithium secondary battery including a lithium cobalt-based oxide; a method of preparing the same; and a lithium secondary battery including a positive electrode for a lithium secondary battery including the composite positive active material are provided. The composite positive active material for a lithium secondary battery includes the lithium cobalt-based oxide, a particle coating part in a form of islands on one surface of the lithium cobalt-based oxide, the particle coating part including a first coating layer containing lithium titanium-based oxide, and a surface coating part in an internal region of another surface of the lithium cobalt-based oxide.