Battery, battery module, battery pack and electric device
A battery, a battery module, a battery pack and an electric device are provided. In some embodiments, the battery includes: a positive electrode, a separator and a negative electrode, wherein the separator includes a base film, a first coating provided on a first surface of the base film, and a second coating provided on a second surface of the base film, the first coating includes a first polar substance, and hydrogen bonds are formed between the first polar substance and a positive binder; hydrogen bonds are formed between the second polar substance and a negative binder and/or a negative active component. In the present disclosure, binding forces between the separator and the positive electrode and the negative electrode may be increased by the hydrogen bonds, thus reducing a cycle expansion rate of a bare cell and improving a high-rate discharge performance and a cycle performance of the battery.
1. A battery, comprising:
a positive electrode, a separator and a negative electrode, wherein the separator comprises a base film, a first coating provided on a first surface of the base film, and a second coating provided on a second surface of the base film, the positive electrode comprises a positive film layer, the negative electrode comprises a negative film layer, wherein
the first coating comprises a first polar substance, the first polar substance comprises polyethylene oxide and polyacrylamide, and hydrogen bonds are formed between the first polar substance and a positive binder of the positive film layer; and
the second coating comprises a second polar substance, the second polar substance comprises polyethylene imine and polyethylene oxide, and hydrogen bonds are formed between the second polar substance and a negative binder and/or a negative active component of the negative film layer,
wherein a peeling force between the first coating and the positive electrode is not lower than 0.075N; a peeling force between the second coating and the negative electrode is not lower than 0.075N;
the first polar substance has a mass content w 1 of 80%-90% in the first coating, and the positive binder has a mass content m 1 of 0.9%-1.2% in the positive film layer; and
the second polar substance has a mass content w 2 of 80%-90% in the second coating, and the negative binder has a mass content m 2 of 2%-3% in the negative film layer.
2. The battery according to claim 1 ,
wherein the mass content w 1 of the first polar substance in the first coating and the mass content m 1 of the positive binder in a positive film layer have a ratio
w
1
m
1
of (80-100):1; and
the mass content w 2 of the second polar substance in the second coating and the mass content m 2 of the negative binder in a negative film layer have a ratio
w
2
m
2
of (32-50):1.
3. The battery according to claim 1 ,
wherein the mass content w 1 of the first polar substance in the first coating and the mass content w 2 of the second polar substance in the second coating have a ratio
w
1
w2
of 1:(1-1.3).
4. The battery according to claim 1 ,
the polyethylene oxide and the polyacrylamide have a mass ratio C1 of (2-6):1; and
the polyethylene imine and the polyethylene oxide have a mass ratio C2 of (2-6):1.
5. The battery according to claim 1 ,
wherein the first coating comprises a first reinforcing agent, and the mass content w 1 of the first polar substance in the first coating and a mass content k 1 of the first reinforcing agent in the first coating have a mass ratio
w
1
k
1
of (5-9):1; and the second coating comprises a second reinforcing agent, and the mass content w 2 of the second polar substance in the second coating and a mass content k 2 of the second reinforcing agent in the second coating have a mass ratio
w2
k
2
of (5-9):1.
6. The battery according to claim 5 ,
wherein the mass content k 1 of the first reinforcing agent in the first coating is not higher than the mass content k 2 of the second reinforcing agent in the second coating.
7. The battery according to claim 6 ,
wherein the mass content k 1 of the first reinforcing agent in the first coating and the mass content k 2 of the second reinforcing agent in the second coating have a ratio
k
1
k
2
of (0.8-1):1.
8. The battery according to claim 7 ,
wherein the first reinforcing agent or the second reinforcing agent comprises one or more of polyvinylidene difluoride and sodium alginate; and
the positive binder comprises polyvinylidene difluoride, and the negative binder comprises more than one of styrene butadiene rubber and sodium alginate.
9. The battery according to claim 1 ,
wherein the negative active component comprises a silicon-carbon mixture, silicon in the silicon-carbon mixture has a particle size of 0.1-0.5 microns, carbon in the silicon-carbon mixture is mixed carbon of artificial graphite and natural graphite, and the silicon-carbon mixture has a content of 95%-97% in the negative film layer.
10. The battery according to claim 1 ,
wherein the first coating and the second coating have a mass ratio of 1:(1-1.5).
11. The battery according to claim 7 ,
wherein the first coating is prepared from a first coating slurry, and the first coating slurry comprises the first polar substance, the first reinforcing agent and a first solvent,
wherein the first coating slurry has a viscosity of 8,000 mPa·s-12,000 mPa·s; and
the second coating is prepared from a second coating slurry, and the second coating slurry comprises the second polar substance, the second reinforcing agent and a second solvent;
wherein the second coating slurry has a viscosity of 5,000 mPa·s-20,000 mPa·s.
12. The battery according to claim 1 ,
wherein the positive film layer comprises a positive material LiNi x Co y Mn z O 2 , where x+y+z=1, and x=0.4-0.9.
13. A battery module, comprising the battery according to claim 1 .
14. A battery pack, comprising the battery module according to claim 13 .
15. The battery according to claim 1 , wherein the first polar substance further comprises one or more of polyolefin imine, polyurethane, and polyurea.
16. The battery according to claim 1 , wherein the second polar substance further comprises one or more of polyolefin amide, polyurethane, and polyurea.