Positive electrode sheet, secondary battery, battery module, battery pack and electrical apparatus

Abstract

A positive electrode sheet, a secondary battery, a battery module, a battery pack and an electrical apparatus are described. The positive electrode sheet includes a positive electrode current collector and a positive electrode film layer arranged on at least one surface of the positive electrode current collector and having a single-layer or multi-layer structure. When the positive electrode film layer is of the single-layer structure, at least one positive electrode film layer comprises both a first positive electrode active material and a second positive electrode active material with a chemical formula of Li a A x Mn 1-y R y P 1-z C z O 4-n D n ; and/or, when the positive electrode film layer is of the multi-layer structure, at least one layer of the at least one positive electrode film layer includes both a first and second positive electrode active material. The secondary battery made of the positive electrode sheet has high energy density and high battery cell rate performance.

1 . 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 is of a single-layer structure or a multi-layer structure; when the positive electrode film layer it is of the single-layer structure, at least one positive electrode film layer comprises both a first positive electrode active material and a second positive electrode active material with a chemical formula of Li a A x Mn 1-y R y P 1-z C z O 4-n D n ; and/or, when the positive electrode film layer is of the multi-layer structure, at least one layer of the at least one positive electrode film layer comprises both a first positive electrode active material and a second positive electrode active material with a chemical formula of Li a A x Mn 1-y R y P 1-z C z O 4-n D n ;
 wherein,   A comprises one or more elements selected from Zn, Al, Na, K, Mg, Nb, Mo and W;   R comprises one or more elements selected from Ti, V, Zr, Fe, Ni, Mg, Co, Ga, Sn, Sb, Nb and Ge;   C comprises one or more elements selected from B, S, Si and N;   D comprises one or more elements selected from S, F, Cl and Br;   a is selected from a range of 0.9 to 1.1, x is selected from a range of 0.001 to 0.1, y is selected from a range of 0.001 to 0.5, z is selected from a range of 0.001 to 0.1, and n is selected from a range of 0.001 to 0.1; and   the second positive electrode active material is selected from one or more of LiNi b Co c Mn (1-b-c) O 2 , LiNi b Co c Al (1-b-c) O 2  and LiCoO 2 ; wherein b is independently selected from 0.3-0.9 (optionally 0.33-0.8), and a sum of b and c is independently selected from 0.3-0.9 (optionally 0.66-0.9).   
     
     
         2 . 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; and at least one positive electrode film layer is of a multi-layer structure, and any positive electrode film layer having the multi-layer structure comprises a first positive electrode active material and a second positive electrode active material with a chemical formula of Li a A x Mn 1-y R y P 1-z C z O 4-n D n  in different layers respectively;
 wherein,   A comprises one or more elements selected from Zn, Al, Na, K, Mg, Nb, Mo and W,   R comprises one or more elements selected from Ti, V, Zr, Fe, Ni, Mg, Co, Ga, Sn, Sb, Nb and Ge,   C comprises one or more elements selected from B, S, Si and N,   D comprises one or more elements selected from S, F, Cl and Br,   a is selected from a range of 0.9 to 1.1, x is selected from a range of 0.001 to 0.1, y is selected from a range of 0.001 to 0.5, z is selected from a range of 0.001 to 0.1, and n is selected from a range of 0.001 to 0.1;   the second positive electrode active material is selected from one or more of LiNi b Co c Mn (1-b-c) O 2 , LiNi b Co c Al (1-b-c) O 2  and LiCoO 2 ; wherein b is independently selected from 0.3-0.9 (optionally 0.33-0.8), and a sum of b and c is independently selected from 0.3-0.9 (optionally 0.66-0.9); and   optionally, any positive electrode film layer having the multi-layer structure comprises the first positive electrode active material and the second positive electrode active material in adjacent layers respectively.   
     
     
         3 . A positive electrode sheet, comprising a positive electrode current collector as well as a positive electrode film layer I and a positive electrode film layer II arranged on two surfaces of the positive electrode current collector respectively; the positive electrode film layer I and the positive electrode film layer II are each of a single-layer structure or a multi-layer structure independently; and at least one layer of the positive electrode film layer I comprises a first positive electrode active material with a chemical formula of Li a A x Mn 1-y R y P 1-z C z O 4-n D n , and at the same time, at least one layer of the positive electrode film layer II comprises a second positive electrode active material;
 wherein,   A comprises one or more elements selected from Zn, Al, Na, K, Mg, Nb, Mo and W,   R comprises one or more elements selected from Ti, V, Zr, Fe, Ni, Mg, Co, Ga, Sn, Sb, Nb and Ge,   C comprises one or more elements selected from B, S, Si and N,   D comprises one or more elements selected from S, F, Cl and Br,   a is selected from a range of 0.9 to 1.1, x is selected from a range of 0.001 to 0.1, y is selected from a range of 0.001 to 0.5, z is selected from a range of 0.001 to 0.1, and n is selected from a range of 0.001 to 0.1;   the second positive electrode active material is selected from one or more of LiNi b Co c Mn (1-b-c) O 2 , LiNi b Co c Al (1-b-c) O 2  and LiCoO 2 ; wherein b is independently selected from 0.3-0.9 (optionally 0.33-0.8), and a sum of b and c is independently selected from 0.3-0.9 (optionally 0.66-0.9).   
     
     
         4 . The positive electrode sheet according to  claim 1 , wherein a mass ratio of the first active material to the second active material is 1:7 to 7:1, and optionally 1:4 to 4:1. 
     
     
         5 . The positive electrode sheet according to  claim 2 , wherein a mass ratio of the first active material to the second active material is 1:7 to 7:1, and optionally 1:4 to 4:1. 
     
     
         6 . The positive electrode sheet according to  claim 3 , wherein a mass ratio of the first active material to the second active material is 1:7 to 7:1, and optionally 1:4 to 4:1. 
     
     
         7 . The positive electrode sheet according to  claim 1 , wherein in the first positive electrode active material.
 R is selected from at least two elements of Ti, V, Zr, Fe, Ni, Mg, Co, Ga, Sn, Sb, Nb and Ge;   optionally,   A is any element selected from Mg and Nb, and/or,   R is at least two elements selected from Fe, Ti, V, Co and Mg, optionally Fe and one or more elements selected from Ti, V, Co and Mg, and/or,   C is S, and/or,   D is F.   
     
     
         8 . The positive electrode sheet according to  claim 2 , wherein in the first positive electrode active material,
 R is selected from at least two elements of Ti, V, Zr, Fe, Ni, Mg, Co, Ga, Sn, Sb, Nb and Ge;   optionally,   A is any element selected from Mg and Nb, and/or,   R is at least two elements selected from Fe, Ti, V, Co and Mg, optionally Fe and one or more elements selected from Ti, V, Co and Mg, and/or,   C is S, and/or,   D is F.   
     
     
         9 . The positive electrode sheet according to  claim 3 , wherein in the first positive electrode active material,
 R is selected from at least two elements of Ti, V, Zr, Fe, Ni, Mg, Co, Ga, Sn, Sb, Nb and Ge;   optionally,   A is any element selected from Mg and Nb, and/or,   R is at least two elements selected from Fe, Ti, V, Co and Mg, optionally Fe and one or more elements selected from Ti, V, Co and Mg, and/or,   C is S, and/or,   D is F.   
     
     
         10 . The positive electrode sheet according to  claim 1 , wherein in the first positive electrode active material, x is selected from a range of 0.001-0.005; and/or, y is selected from a range of 0.01 to 0.5, optionally selected from a range of 0.25 to 0.5; and/or, z is selected from a range of 0.001 to 0.005; and/or, n is selected from a range of 0.001 to 0.005; and/or, a ratio of (1-y) to y is selected from 1-4, optionally selected from 1.5-3; and/or, a ratio of a to x is selected from 9-1100, optionally selected from 190-998. 
     
     
         11 . The positive electrode sheet according to  claim 2 , wherein in the first positive electrode active material, x is selected from a range of 0.001-0.005; and/or, y is selected from a range of 0.01 to 0.5, optionally selected from a range of 0.25 to 0.5; and/or, z is selected from a range of 0.001 to 0.005; and/or, n is selected from a range of 0.001 to 0.005; and/or, a ratio of (1-y) to y is selected from 1-4, optionally selected from 1.5-3; and/or, a ratio of a to x is selected from 9-1100, optionally selected from 190-998. 
     
     
         12 . The positive electrode sheet according to  claim 3 , wherein in the first positive electrode active material, x is selected from a range of 0.001-0.005; and/or, y is selected from a range of 0.01 to 0.5, optionally selected from a range of 0.25 to 0.5; and/or, z is selected from a range of 0.001 to 0.005; and/or, n is selected from a range of 0.001 to 0.005; and/or, a ratio of (1-y) to y is selected from 1-4, optionally selected from 1.5-3; and/or, a ratio of a to x is selected from 9-1100, optionally selected from 190-998. 
     
     
         13 . The positive electrode sheet according to  claim 1 , wherein a lattice change rate of the first positive electrode active material is below 8%, optionally below 4%. 
     
     
         14 . The positive electrode sheet according to  claim 2 , wherein a lattice change rate of the first positive electrode active material is below 8%, optionally below 4%. 
     
     
         15 . The positive electrode sheet according to  claim 3 , wherein a lattice change rate of the first positive electrode active material is below 8%, optionally below 4%. 
     
     
         16 . The positive electrode sheet according to  claim 1 , wherein a Li/Mn antisite defect concentration of the first positive electrode active material is below 2%, optionally below 0.5%. 
     
     
         17 . The positive electrode sheet according to  claim 2 , wherein a Li/Mn antisite defect concentration of the first positive electrode active material is below 2%, optionally below 0.5%. 
     
     
         18 . The positive electrode sheet according to  claim 3 , wherein a Li/Mn antisite defect concentration of the first positive electrode active material is below 2%, optionally below 0.5%. 
     
     
         19 . The positive electrode sheet according to  claim 1 , wherein surface oxygen valence of the first positive electrode active material is below −1.82, optionally −1.89 to −1.98. 
     
     
         20 . The positive electrode sheet according to  claim 2 , wherein surface oxygen valence of the first positive electrode active material is below −1.82, optionally −1.89 to −1.98. 
     
     
         21 . The positive electrode sheet according to  claim 3 , wherein surface oxygen valence of the first positive electrode active material is below −1.82, optionally −1.89 to −1.98. 
     
     
         22 . The positive electrode sheet according to  claim 1 , wherein a compacted density of the first positive electrode active material at 3 T is 2.0 g/cm 3  or more, optionally 2.2 g/cm 3  or more. 
     
     
         23 . The positive electrode sheet according to  claim 2 , wherein a compacted density of the first positive electrode active material at 3 T is 2.0 g/cm 3  or more, optionally 2.2 g/cm 3  or more. 
     
     
         24 . The positive electrode sheet according to  claim 3 , wherein a compacted density of the first positive electrode active material at 3 T is 2.0 g/cm 3  or more, optionally 2.2 g/cm 3  or more. 
     
     
         25 . The positive electrode sheet according to  claim 1 , wherein a surface of the first positive electrode active material is further coated with carbon. 
     
     
         26 . The positive electrode sheet according to  claim 2 , wherein a surface of the first positive electrode active material is further coated with carbon. 
     
     
         27 . The positive electrode sheet according to  claim 3 , wherein a surface of the first positive electrode active material is further coated with carbon. 
     
     
         28 . The positive electrode sheet according to  claim 1 , wherein in the first positive electrode active material,
 a ratio of b to (1-b-c) to c in LiNi b Co c Mn (1-b-c) O 2  is 5:2:3 or 3:1:1 or 8:1:1; and/or,   a ratio of b to c to (1-b-c) in LiNi b Co c Al (1-b-c) O 2  is 5:2:3 or 3:1:1 or 8:1:1.   
     
     
         29 . The positive electrode sheet according to  claim 2 , wherein in the first positive electrode active material,
 a ratio of b to (1-b-c) to c in LiNi b Co c Mn (1-b-c) O 2  is 5:2:3 or 3:1:1 or 8:1:1; and/or,   a ratio of b to c to (1-b-c) in LiNi b Co c Al (1-b-c) O 2  is 5:2:3 or 3:1:1 or 8:1:1.   
     
     
         30 . The positive electrode sheet according to  claim 3 , wherein in the first positive electrode active material,
 a ratio of b to (1-b-c) to c in LiNi b Co c Mn (1-b-c) O 2  is 5:2:3 or 3:1:1 or 8:1:1; and/or,   a ratio of b to c to (1-b-c) in LiNi b Co c Al (1-b-c) O 2  is 5:2:3 or 3:1:1 or 8:1:1.   
     
     
         31 . The positive electrode sheet according to  claim 1 , wherein a sum of mass of the first positive electrode active material and the second positive electrode active material accounts for 88%-98.7% of mass of the positive electrode sheet. 
     
     
         32 . The positive electrode sheet according to  claim 2 , wherein a sum of mass of the first positive electrode active material and the second positive electrode active material accounts for 88%-98.7% of mass of the positive electrode sheet. 
     
     
         33 . The positive electrode sheet according to  claim 3 , wherein a sum of mass of the first positive electrode active material and the second positive electrode active material accounts for 88%-98.7% of mass of the positive electrode sheet. 
     
     
         34 . A secondary battery, comprising the positive electrode sheet according to  claim 1 . 
     
     
         35 . A secondary battery, comprising the positive electrode sheet according to  claim 2 . 
     
     
         36 . A secondary battery, comprising the positive electrode sheet according to  claim 3 . 
     
     
         37 . A battery module, comprising the secondary battery according to  claim 34 . 
     
     
         38 . A battery module, comprising the secondary battery according to  claim 35 . 
     
     
         39 . A battery module, comprising the secondary battery according to  claim 36 . 
     
     
         40 . A battery pack, comprising the battery module according to  claim 37 . 
     
     
         41 . A battery pack, comprising the battery module according to  claim 38 . 
     
     
         42 . A battery pack, comprising the battery module according to  claim 39 . 
     
     
         43 . An electrical apparatus, comprising at least one of the secondary battery according to  claim 34 . 
     
     
         44 . An electrical apparatus, comprising at least one of the secondary battery according to  claim 35 . 
     
     
         45 . An electrical apparatus, comprising at least one of the secondary battery according to  claim 36 .