In a method of recovering an active metal of a lithium secondary battery, a cathode active material mixture is prepared from a waste cathode of a lithium secondary. The cathode active material mixture is reacted with a reductive reaction gas to form a preliminary precursor mixture having a reduction degree of transition metal defined by Equation 1 in a range from 0.24 to 1.6. A lithium precursor is recovered from the preliminary precursor mixture. A lithium recovery rationis improved by adjusting the reduction degree of transition metal.

A secondary battery includes a positive electrode, a negative electrode, and an electrolytic solution. The positive electrode includes a positive electrode active material layer. The positive electrode active material layer includes a lithium-nickel composite oxide of a layered rock-salt type.

A secondary battery includes a positive electrode, a negative electrode, and an electrolytic solution. The positive electrode includes a positive electrode active material layer. The positive electrode active material layer includes a lithium-nickel composite oxide of a layered rock-salt type.

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-1) immersing a positive electrode scrap comprising an active material layer on a current collector into a basic solution to separate the active material layer from the current collector, (a-2) thermally treating the active material layer in air for thermal decomposition of a binder and a conductive material in the active material layer, and collecting an active material in the active material layer, (b) washing the active material collected from the step (a-2) with a lithium compound solution which is basic in an aqueous solution and drying, and (c) annealing the active material washed from the step (b) with a lithium precursor to obtain a reusable active material.

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-1) immersing a positive electrode scrap comprising an active material layer on a current collector into a basic solution to separate the active material layer from the current collector, (a-2) thermally treating the active material layer in air for thermal decomposition of a binder and a conductive material in the active material layer, and collecting an active material in the active material layer, (b) washing the active material collected from the step (a-2) with a lithium compound solution which is basic in an aqueous solution and drying, and (c) annealing the active material washed from the step (b) with a lithium precursor to obtain a reusable active material.

A battery pack including heterogeneous secondary batteries includes: a first battery set in which a plurality of first secondary batteries are stacked; and a second battery set in which a plurality of second secondary batteries are stacked, in which each of the first battery set and the second battery set is formed of a plurality, and the battery pack has an arrangement structure in which the plurality of first battery sets and the plurality of second battery sets are alternately stacked in one direction.

A battery pack including heterogeneous secondary batteries includes: a first battery set in which a plurality of first secondary batteries are stacked; and a second battery set in which a plurality of second secondary batteries are stacked, in which each of the first battery set and the second battery set is formed of a plurality, and the battery pack has an arrangement structure in which the plurality of first battery sets and the plurality of second battery sets are alternately stacked in one direction.

A lithium transition metal oxide electrode including an additional metal is provided herein as well electrochemical cells including the lithium transition metal oxide electrode and methods of making the lithium transition metal oxide electrode. The lithium transition metal oxide electrode includes a first electroactive material including Li.sub.1+aNi.sub.bMn.sub.cM.sub.dO.sub.2, where 0.05≤a≤0.6; 0.01≤b≤0.5; 0.1≤c≤0.9; zero (0)≤d≤0.3; b+c+d=1 or a+b+c+d=1; and M represents an additional metal, such as W, Mo, V, Zr, Nb, Ta, Fe, Al, Mg, Si, or a combination thereof.

A lithium transition metal oxide electrode including an additional metal is provided herein as well electrochemical cells including the lithium transition metal oxide electrode and methods of making the lithium transition metal oxide electrode. The lithium transition metal oxide electrode includes a first electroactive material including Li.sub.1+aNi.sub.bMn.sub.cM.sub.dO.sub.2, where 0.05≤a≤0.6; 0.01≤b≤0.5; 0.1≤c≤0.9; zero (0)≤d≤0.3; b+c+d=1 or a+b+c+d=1; and M represents an additional metal, such as W, Mo, V, Zr, Nb, Ta, Fe, Al, Mg, Si, or a combination thereof.

The present application relates to a battery module, which includes a first type of battery cells and a second type of battery cells electrically connected in series. The first type of battery cells and the second type of battery cells are battery cells with different chemical systems. The first type of battery cells includes N first battery cells, and the second type of battery cells includes M second battery cells, where N and M are greater than or equal one. The present application also relates to a battery pack and an electric apparatus including the battery module, and method and device for manufacturing the battery module.