Polymer current collector, preparation method thereof, and secondary battery, battery module, battery pack, and apparatus associated therewith
This application provides a polymer current collector, a preparation method thereof, and a secondary battery, battery module, battery pack, and apparatus associated therewith. The polymer current collector provided in this application includes polymer film layers, where the polymer film layers include a first polymer film layer and a second polymer film layer, a resistivity of the first polymer film layer is denoted as ρ1, a resistivity of the second polymer film layer is denoted as ρ2, and the current collector satisfies ρ1>ρ2. The polymer current collector in this application can induce to deposit of lithium metal from a low conductivity side to a high conductivity side, avoiding risks of depositing lithium ions on the surface of the current collector and thereby increasing cycle life of lithium metal batteries.
1. A polymer current collector, comprising a first polymer film layer and a second polymer film layer, a resistivity of the first polymer film layer is denoted as ρ1, a resistivity of the second polymer film layer is denoted as ρ2, ρ1 satisfies 10 3 Ω·cm≤ρ1≤10 6 Ω·cm, ρ1 satisfies 10 Ω·cm≤ρ2≤1000 Ω·cm, ρ1>ρ2, a thickness of the first polymer film layer is 5 μm to 100 μm, a thickness of the second polymer film layer is 5 μm to 100 μm, and the first polymer film layer and the second polymer film layer each comprise a sintering product of a polymer precursor, and the polymer precursor is selected from the group consisting of nitrile polymer, alcohol polymer, cellulose polymer, sulfone polymer, amine polymer, ester polymer, ketone polymer, melamine foam, cotton fiber, or a combination thereof.
2. The polymer current collector according to claim 1 , wherein ρ1/ρ2≥40.
3. The polymer current collector according to claim 1 , wherein
in the first polymer film layer, a variation of C/N is 0.1 to 10; and
in the first polymer film layer, a variation of C/O is 0.1 to 10.
4. The polymer current collector according to claim 1 , wherein
in the second polymer film layer, a variation of C/N is 0.1 to 15; and
in the second polymer film layer, a variation of C/O is 0.1 to 15.
5. The polymer current collector according to claim 1 , wherein a quantity of the polymer film layers is greater than 2.
6. The polymer current collector according to claim 1 , wherein the polymer current collector further comprises a third polymer film layer, the second polymer film layer is disposed between the third polymer film layer and the first polymer film layer, a resistivity of the third polymer film layer is denoted as ρ3, a thickness of the third polymer film layer is 5 μm to 100 μm, and the current collector further satisfies ρ2>ρ3.
7. The polymer current collector according to claim 6 , wherein the polymer current collector further satisfies one or more of the following conditions:
(1) 20≤ρ2/ρ3≤1000;
(2) 1≤ρ3≤500 Ω·cm;
(3) in the third polymer film layer, a variation of C/N is 0.3 to 20; and
(4) in the third polymer film layer, a variation of C/O is 0.3 to 20.
8. The polymer current collector according to claim 7 , wherein the thickness of the third polymer film layer is 10 μm to 50 μm.
9. The polymer current collector according to claim 1 , wherein the polymer current collector is a porous structure.
10. The polymer current collector according to claim 1 , wherein the thickness of the first polymer film layer is 10 μm to 50 μm, and the thickness of the second polymer film layer is 10 μm to 50 μm.
11. The polymer current collector according to claim 1 , wherein the polymer precursor is selected from the group consisting of polyacrylonitrile, polyvinyl alcohol, carboxymethyl cellulose, polysulfuriamide, or any combination thereof.
12. A preparation method of the polymer current collector according to claim 1 , comprising the following steps:
S1: providing two or more than two polymer films having different resistivities; and
S2: pressing the polymer films in S1 in descending or ascending order of resistivities to obtain the polymer current collector;
wherein the polymer current collector comprises polymer film layers, the polymer film layers comprise a first polymer film layer and a second polymer film layer, a resistivity of the first polymer film layer is denoted as ρ1, a resistivity of the second polymer film layer is denoted as ρ2, and the current collector satisfies ρ1>ρ2.
13. The preparation method according to claim 12 , wherein a preparation method of the polymer films comprises the following steps:
(1) providing two or more than two polymer film precursors comprising a same polymer raw material; and
(2) subjecting the polymer film precursors in (1) to sintering, wherein the polymer film precursors each are sintered at different temperatures to obtain polymer films having different resistivities.
14. The preparation method according to claim 13 , wherein the sintering temperature is 200 degree Celsius (° C.) to 2000° C.
15. The preparation method according to claim 14 , wherein the polymer raw material comprises one or more of nitrile polymer, alcohol polymer, cellulose polymer, sulfone polymer, amine polymer, ester polymer, ketone polymer, melamine foam, and cotton fiber.
16. A secondary battery, comprising a negative electrode plate, wherein the negative electrode plate comprises the polymer current collector according to claim 1 .
17. The secondary battery according to claim 16 , wherein the secondary battery further comprises a separator, and the first polymer film layer is closer to the separator than the second polymer film layer.
18. The secondary battery according to claim 17 , wherein the secondary battery is a lithium metal secondary battery, a potassium metal secondary battery, or a sodium secondary battery.
19. An apparatus, comprising at least one of the secondary battery according to claim 16 .