The disclosure relates to porous Co.sub.3O.sub.4 nanoparticles which include flocculated amorphous primary nanoparticles, with air pores formed between the amorphous primary nanoparticles. The porous Co.sub.3O.sub.4 nanoparticles, according to an embodiment of the disclosure, may be in the form of flocculated amorphous primary nanoparticles of 1 nm or less, have a 400 times larger specific surface area than the conventional Co.sub.3O.sub.4 particles, and address the issue with the expansion of Co.sub.3O.sub.4 lattices which may arise when the battery is charged or discharged, thereby providing more reliability when applied to batteries.

The disclosure relates to porous Co.sub.3O.sub.4 nanoparticles which include flocculated amorphous primary nanoparticles, with air pores formed between the amorphous primary nanoparticles. The porous Co.sub.3O.sub.4 nanoparticles, according to an embodiment of the disclosure, may be in the form of flocculated amorphous primary nanoparticles of 1 nm or less, have a 400 times larger specific surface area than the conventional Co.sub.3O.sub.4 particles, and address the issue with the expansion of Co.sub.3O.sub.4 lattices which may arise when the battery is charged or discharged, thereby providing more reliability when applied to batteries.

In a method for recovering an active metal of a lithium secondary battery, a cathode active material mixture is prepared from a cathode of a lithium secondary battery. A first reductive process using a first reductive reaction gas and a second reductive process using a second reductive reaction gas that has a higher reaction source concentration than that of the first reductive reaction gas are performed sequentially and continuously to convert the cathode active material mixture into a preliminary precursor mixture. A lithium precursor is recovered from the preliminary precursor mixture. A lithium recovery ratio may be increased by a stepwise reduction while preventing an increase of heating value.

A porous body comprises a framework having a three-dimensional network structure, the framework having a body including nickel and cobalt as constituent elements, the body of the framework including the cobalt at a proportion in mass of 0.2 or more and 0.8 or less relative to a total mass of the nickel and the cobalt, the framework having a surface with an arithmetic mean roughness of 0.05 μm or more, the porous body being increased in volume by 1% or more for a shape of an external appearance thereof after the porous body undergoes a heat treatment in the atmosphere at 800° C. for 200 hours with a load of 16 kPa applied.

A porous body comprises a framework having a three-dimensional network structure, the framework having a body including nickel and cobalt as constituent elements, the body of the framework including the cobalt at a proportion in mass of 0.2 or more and 0.8 or less relative to a total mass of the nickel and the cobalt, the framework having a surface with an arithmetic mean roughness of 0.05 μm or more, the porous body being increased in volume by 1% or more for a shape of an external appearance thereof after the porous body undergoes a heat treatment in the atmosphere at 800° C. for 200 hours with a load of 16 kPa applied.

One aspect of the present invention is a positive active material that contains an oxide containing lithium, a transition metal element and a typical element, and having an antifluorite crystal structure, in which the transition metal element is cobalt, iron, copper, manganese, nickel, chromium, or a combination thereof, the typical element is a group 13 element, a group 14 element, phosphorus, antimony, bismuth, tellurium or a combination thereof, and a molar ratio of a content of the typical element to a total content of the transition metal element and the typical element in the oxide is more than 0.05 and 0.5 or less.

One aspect of the present invention is a positive active material that contains an oxide containing lithium, a transition metal element and a typical element, and having an antifluorite crystal structure, in which the transition metal element is cobalt, iron, copper, manganese, nickel, chromium, or a combination thereof, the typical element is a group 13 element, a group 14 element, phosphorus, antimony, bismuth, tellurium or a combination thereof, and a molar ratio of a content of the typical element to a total content of the transition metal element and the typical element in the oxide is more than 0.05 and 0.5 or less.

The present invention discloses a preparation method for high density aluminum doped cobalt oxide, which comprises following steps: 1) adding a cobalt salt solution, an alkaline solution and an oxidizer to a reactor for reaction; adding an aluminum cobalt solution to the reaction system for reaction; stopping adding the aluminum cobalt solution after D50 reaches 3.5-4.0 μm, stopping the reaction when D50 reaches the desired particle size, thus obtaining aluminiferous cobalt oxyhydroxide slurry; 2) aging, dehydrating, washing and drying the aluminiferous cobalt oxyhydroxide slurry, thus obtaining aluminiferous cobalt oxyhydroxide powder; 3) calcining the aluminiferous cobalt oxyhydroxide powder, thus obtaining the target object. With the method of the present invention, doped aluminum can be perfectly embedded into cobalt oxide lattices, thus effectively enhancing the tap density and uniformity of aluminum doped cobalt oxide and improving the cycle performance and charge-discharge performance of batteries.

The present invention discloses a preparation method for high density aluminum doped cobalt oxide, which comprises following steps: 1) adding a cobalt salt solution, an alkaline solution and an oxidizer to a reactor for reaction; adding an aluminum cobalt solution to the reaction system for reaction; stopping adding the aluminum cobalt solution after D50 reaches 3.5-4.0 μm, stopping the reaction when D50 reaches the desired particle size, thus obtaining aluminiferous cobalt oxyhydroxide slurry; 2) aging, dehydrating, washing and drying the aluminiferous cobalt oxyhydroxide slurry, thus obtaining aluminiferous cobalt oxyhydroxide powder; 3) calcining the aluminiferous cobalt oxyhydroxide powder, thus obtaining the target object. With the method of the present invention, doped aluminum can be perfectly embedded into cobalt oxide lattices, thus effectively enhancing the tap density and uniformity of aluminum doped cobalt oxide and improving the cycle performance and charge-discharge performance of batteries.

The present invention discloses a preparation method for 2-4 μm battery-grade cobalt tetroxide, comprises following steps: 1) adding a cobalt salt solution and an alkaline solution by parallel flows to a reactor with a base solution and an air flow, controlling pH value of a system by adjusting flow rate of the alkaline solution for coprecipitation reaction at a certain stirring rate, decreasing the pH value of the reaction system and increasing flow rate of the cobalt salt solution after the reaction solutions begin to overflow; 2) aging and drying the cobalt oxyhydroxide slurry in sequence; 3) calcining the dried cobalt oxyhydroxide. By adopting this method, tap density of the battery-grade cobalt tetroxide obtained is much higher than that of cobalt tetroxide with a same particle size specification prepared by the prior art.