LAYERED OXIDE AND PREPARATION METHOD THEREOF, POSITIVE ELECTRODE SHEET, SECONDARY BATTERY, BATTERY MODULE, BATTERY PACK AND ELECTRICAL APPARATUS
Provided are a layered oxide and a preparation method thereof, a positive electrode sheet, a secondary battery, a battery module, a battery pack and an electrical apparatus. The layered oxide includes an oxide with the general formula Na x Mn y A a Q b C c O 2 , where A is one or two of Fe and Ni; Q is one or more of transition metal elements containing 3d or 4d orbital electrons except Fe and Ni; C is one or two of Al and B, 0.66<x≤1, 0.2≤y≤0.6, 0.3≤a≤0.6, 0<b≤0.2, 0<c≤0.1, and 1≤b/c≤100. The A element undergoes valence changes to provide charge compensation in a charge and discharge process, thereby improving the specific capacity of the layered oxide; the Q element and oxygen form a hybrid orbital, inhibiting irreversible oxygen losses and structure collapse of oxygen under a high voltage; the C element has a high ionic potential so as to effectively inhibit oxygen losses; and 1≤b/c≤100.
1 . A layered oxide, comprising an oxide with a general formula Na x Mn y A a Q b C c O 2 , wherein A is one or two of Fe and Ni; Q is one or more of transition metal elements containing 3d or 4d orbital electrons except Fe and Ni; C is one or two of Al and B, 0.66<x≤1, 0.2≤y≤0.6, 0.3≤a≤0.6, 0<b≤0.2, 0<c≤0.1, and 1≤b/c≤100.
2 . The layered oxide according to claim 1 , wherein the Q is selected from one or more of the group consisting of Cu, Zn, Y and Ti.
3 . The layered oxide according to claim 1 , wherein the A contains Fe and Ni.
4 . The layered oxide according to claim 1 , wherein a phase state of the layered oxide is an O3 phase, and a space group is R 3 m.
5 . The layered oxide according to claim 1 , wherein an interlayer distance d 003 of a (003) crystal face of the layered oxide is 0.53 nm to 0.55 nm.
6 . The layered oxide according to claim 1 , wherein an intensity of a (003) characteristic peak in an X-ray diffraction spectrum of the layered oxide before soaking is I0, the intensity of the (003) characteristic peak in the X-ray diffraction spectrum of the layered oxide after 24 h room-temperature soaking in water is I1, and I1/I0≥0.2.
7 . The layered oxide according to claim 1 , wherein the pH value of an aqueous solution of the layered oxide with a mass concentration of 10% is between 11 and 13.
8 . The layered oxide according to claim 1 , wherein a volume average particle diameter D v50 of the layered oxide is 3 μm to 30 μm.
9 . The layered oxide according to claim 1 , wherein a specific surface area BET of the layered oxide is 0.1 m 2 /g to 5 m 2 /g.
10 . The layered oxide according to claim 1 , wherein a tap density of the layered oxide is 1 g/cm 3 to 3 g/cm 3 .
11 . The layered oxide according to claim 1 , wherein a powder compaction density of the layered oxide under a pressure of 300 MPa is 3.0 g/cm 3 to 4.0 g/cm 3 .
12 . A preparation method of a layered oxide, comprising:
step S1, mixing layered oxides of a Na source, a Mn source, an A source, a Q source and a C source to obtain a precursor powder, wherein the Na source, the Mn source, the A source, the Q source and the C source are mixed according to a molar ratio of Na:Mn:A:Q:C being (0.85-1.2):(0.2-0.6):(0.3-0.6):(0-0.2):(0-0.1), a mole number of the Q and the C is not 0, an A element in the A source is one or two of Fe and Ni, an A element in the Q source is one or more of transition metal elements containing 3d or 4d orbital electrons except Fe and Ni, and a C element in the C source is one or two of Al and B; and
step S2: calcining the precursor powder in an oxidizing atmosphere and crushing a resulting material to obtain the layered oxide,
wherein optionally, step S1 implements the mixing by a ball milling or mechanical stirring method.
13 . The preparation method according to claim 12 , wherein the oxidizing atmosphere is selected from air, oxygen, mixed gas of air and oxygen, and mixed gas of oxygen and inert gas.
14 . A positive electrode sheet, comprising a positive electrode current collector and a positive electrode film layer arranged on at least one surface of the positive electrode current collector, wherein the positive electrode film layer comprises a positive electrode active material, and the positive electrode active material comprises the layered oxide according to claim 1 , or the layered oxide prepared by the preparation method according to claim 12 .
15 . A secondary battery, comprising the layered oxide according to claim 1 , or the layered oxide prepared by the preparation method according to claim 12 , or a positive electrode sheet according to claim 14 .
16 . A battery module, comprising a secondary battery, wherein the secondary battery is the secondary battery according to claim 15 .
17 . A battery pack, comprising a battery module, wherein the battery module is the battery module according to claim 16 .
18 . An electrical apparatus, comprising a secondary battery or a battery module or a battery pack, wherein the secondary battery is selected from the secondary battery according to claim 15 , the battery module is the battery module according to claim 16 , or the battery pack is the battery pack according to claim 17 .