A compound for use in a lithium, manganese-rich cathode for a Li-ion battery is doped Li.sub.1.2Ni.sub.0.2Mn.sub.0.6O.sub.2 including Li.sub.1.2Ni.sub.0.2Mn.sub.0.6O.sub.2 doped with Na.sup.+, Li.sub.1.2Ni.sub.0.2Mn.sub.0.6O.sub.2 doped with Co.sup.3+, or Li.sub.1.2Ni.sub.0.2Mn.sub.0.6O.sub.2 dual doped with Na.sup.+ and Co.sup.3+. A lithium, manganese-rich cathode for an Li-ion battery includes the aforementioned compound. A lithium-ion battery includes an anode, a cathode, and an electrolyte, wherein the cathode is the aforementioned lithium, manganese-rich cathode.

A compound for use in a lithium, manganese-rich cathode for a Li-ion battery is doped Li.sub.1.2Ni.sub.0.2Mn.sub.0.6O.sub.2 including Li.sub.1.2Ni.sub.0.2Mn.sub.0.6O.sub.2 doped with Na.sup.+, Li.sub.1.2Ni.sub.0.2Mn.sub.0.6O.sub.2 doped with Co.sup.3+, or Li.sub.1.2Ni.sub.0.2Mn.sub.0.6O.sub.2 dual doped with Na.sup.+ and Co.sup.3+. A lithium, manganese-rich cathode for an Li-ion battery includes the aforementioned compound. A lithium-ion battery includes an anode, a cathode, and an electrolyte, wherein the cathode is the aforementioned lithium, manganese-rich cathode.

Please replace the abstract in the specification as filed with the below paragraph as follows: A positive electrode active material for a lithium secondary battery contains secondary particles in which primary particles are aggregated and satisfies (1) the secondary particles each internally have a plurality of voids, a cumulative frequency of 50% in an area-based cumulative frequency distribution of equivalent circle diameters of the voids based on cross-sectional images of the secondary particles is more than 0.2 m and 0.65 m or less, and a cumulative frequency of 50% in an area-based cumulative frequency distribution of circularity of the voids based on cross-sectional images of the secondary particles is 2.2 or more and 6.5 or less; and (2) the primary particles are formed of an oxide containing one or more from the group 1 and one or more from the group 2: group 1: Ni, Co, Mn, Fe, Al, and P; and group 2: Li, Na, K, Ca, Sr, Ba, and Mg.

Please replace the abstract in the specification as filed with the below paragraph as follows: A positive electrode active material for a lithium secondary battery contains secondary particles in which primary particles are aggregated and satisfies (1) the secondary particles each internally have a plurality of voids, a cumulative frequency of 50% in an area-based cumulative frequency distribution of equivalent circle diameters of the voids based on cross-sectional images of the secondary particles is more than 0.2 m and 0.65 m or less, and a cumulative frequency of 50% in an area-based cumulative frequency distribution of circularity of the voids based on cross-sectional images of the secondary particles is 2.2 or more and 6.5 or less; and (2) the primary particles are formed of an oxide containing one or more from the group 1 and one or more from the group 2: group 1: Ni, Co, Mn, Fe, Al, and P; and group 2: Li, Na, K, Ca, Sr, Ba, and Mg.

A positive electrode material is disclosed, represented by the formula LiaNixCoyMn1-x-yMbO2-cQc, where 0.2a1.2, x0.6, y>0, b>0, and c>0. M comprises a high-valence cation and Q comprises an anion. The doping of a high-valence cation and an anion in a nickel-rich ternary material stabilizes the bulk structure during lithium deintercalation, reduces side reactions, lattice oxygen release, and transition metal dissolution, and improves cycling stability, high-temperature storage, and rate capability. The outer surface of the positive electrode material may further include a selenium-containing coating layer that reacts with residual lithium compounds and binds released lattice oxygen to suppress electrolyte oxidation. A conductive coating layer may be formed on the selenium-containing layer to prevent direct contact with the electrolyte and inhibit side reactions.

A positive electrode material is disclosed, represented by the formula LiaNixCoyMn1-x-yMbO2-cQc, where 0.2a1.2, x0.6, y>0, b>0, and c>0. M comprises a high-valence cation and Q comprises an anion. The doping of a high-valence cation and an anion in a nickel-rich ternary material stabilizes the bulk structure during lithium deintercalation, reduces side reactions, lattice oxygen release, and transition metal dissolution, and improves cycling stability, high-temperature storage, and rate capability. The outer surface of the positive electrode material may further include a selenium-containing coating layer that reacts with residual lithium compounds and binds released lattice oxygen to suppress electrolyte oxidation. A conductive coating layer may be formed on the selenium-containing layer to prevent direct contact with the electrolyte and inhibit side reactions.

A modified lithium-rich manganese-based material, a modification method of a lithium-rich manganese-based material, a secondary battery and an electrical device are provided. The modified lithium-rich manganese-based material includes a lithium-rich manganese-based material co-doped with anion and cation and a fast ionic conductor material. The lithium-rich manganese-based material has a chemical formula of xLi.sub.2MnO.sub.3.Math.(1x)LiNi.sub.yCo.sub.zMn.sub.aO.sub.2, where 0<x<1, 0y1, 0z1, and y+z+a=1. A doped cationic element M1 is selected from at least one of a group consisting of Na, Fe, Nb, Ti, Mg, Al, Cr, and Er, and a doped anionic element M2 is selected from at least one of a group consisting of F, Cl, Br, I, S, B, P, N, Se, and Te. The first efficiency, cycle stability, thermal stability, rate performance and capacity of the material are improved.

A modified lithium-rich manganese-based material, a modification method of a lithium-rich manganese-based material, a secondary battery and an electrical device are provided. The modified lithium-rich manganese-based material includes a lithium-rich manganese-based material co-doped with anion and cation and a fast ionic conductor material. The lithium-rich manganese-based material has a chemical formula of xLi.sub.2MnO.sub.3.Math.(1x)LiNi.sub.yCo.sub.zMn.sub.aO.sub.2, where 0<x<1, 0y1, 0z1, and y+z+a=1. A doped cationic element M1 is selected from at least one of a group consisting of Na, Fe, Nb, Ti, Mg, Al, Cr, and Er, and a doped anionic element M2 is selected from at least one of a group consisting of F, Cl, Br, I, S, B, P, N, Se, and Te. The first efficiency, cycle stability, thermal stability, rate performance and capacity of the material are improved.

An apparatus and method for preparing a precursor are described. The apparatus for preparing the precursor is an apparatus for preparing a precursor, which coprecipitation reacts a raw material to prepare the precursor, the apparatus including: a coprecipitation reaction tank in which an accommodated material including a reactant and a remainder is accommodated; and a pH measuring system that measures a pH of the remainder. The pH measuring system includes: a filter that is disposed inside the coprecipitation reaction tank and filters the remainder from the accommodated material; and a pH measuring part that is disposed outside the coprecipitation reaction tank to measure the pH of the remainder filtered through the filter.

An apparatus and method for preparing a precursor are described. The apparatus for preparing the precursor is an apparatus for preparing a precursor, which coprecipitation reacts a raw material to prepare the precursor, the apparatus including: a coprecipitation reaction tank in which an accommodated material including a reactant and a remainder is accommodated; and a pH measuring system that measures a pH of the remainder. The pH measuring system includes: a filter that is disposed inside the coprecipitation reaction tank and filters the remainder from the accommodated material; and a pH measuring part that is disposed outside the coprecipitation reaction tank to measure the pH of the remainder filtered through the filter.