Battery diaphragm and lithium battery prepared therefrom
The present application provides a battery diaphragm, including: a porous substrate and an adhesive layer formed on the side of the porous substrate. The adhesive layer includes a polymer material with an adhesive property. The adhesive layer has a coating coefficient C. The coating coefficient C is equal to a ratio of the adhesive strength A of the adhesive layer to a value P of an increase in gas permeability per unit coating thickness of the adhesive layer. A relation C=A/P is satisfied. The coating coefficient C has a ratio in a range of 0.3<C<1. The adhesive strength A of the adhesive layer has a unit of N/m. The value P of the increase in the gas permeability per unit coating thickness of the adhesive layer has a unit of s/100 cc/μm.
1 . A battery diaphragm, comprising:
a porous substrate; and
an adhesive layer formed on a side of the porous substrate, wherein the adhesive layer comprises a polymer material with an adhesive property, the polymer material comprises vinylidene fluoride (VDF) polymer, a raw material of the vinylidene fluoride polymer has a crystallinity in a range between 10% and 50%, the adhesive layer has a coating coefficient C, the coating coefficient C is equal to a ratio of an adhesive strength A of the adhesive layer to a value P of an increase in gas permeability per unit coating thickness of the adhesive layer, a relation C=A/P is satisfied, the coating coefficient C has a ratio in a range of 0.4<C<0.9, the adhesive strength A of the adhesive layer has a unit of N/m, the value P of the increase in the gas permeability per unit coating thickness of the adhesive layer has a unit of s/100 cc/μm, the adhesive layer is formed by coating aqueous vinylidene fluoride polymer, an α-phase in a crystalline region of the aqueous vinylidene fluoride polymer has a ratio greater than 30% and less than 70%, and the adhesive strength A of the adhesive layer is an adhesive force between the battery diaphragm and an electrode sheet.
2 . A battery diaphragm, comprising:
a porous substrate; and
an adhesive layer formed on a side of the porous substrate, wherein the adhesive layer comprises a polymer material with an adhesive property, the polymer material comprises vinylidene fluoride (VDF) polymer, a raw material of the vinylidene fluoride polymer has a crystallinity in a range between 10% and 50%, the adhesive layer has a coating coefficient C, the coating coefficient C is equal to a ratio of an adhesive strength A of the adhesive layer to a value P of an increase in gas permeability per unit coating thickness of the adhesive layer, a relationship C-A/P is satisfied, the coating coefficient C has a ratio in a range of 0.4<C<0.9, the adhesive strength A of the adhesive layer has a unit of N/m, and the value P of the increase in the gas permeability per unit coating thickness of the adhesive layer has a unit of s/100 cc/μm, the adhesive layer is formed by coating oil-based vinylidene fluoride polymer, an α-phase in a crystalline region of the oil-based vinylidene fluoride polymer has a ratio less than 20%, and the adhesive strength A of the adhesive layer is an adhesive force between the battery diaphragm and an electrode sheet.
3 . A lithium battery, comprising: a positive electrode, a negative electrode and the battery diaphragm according to claim 1 , wherein the battery diaphragm is positioned between the positive electrode and the negative electrode.
4 . A lithium battery, comprising: a positive electrode, a negative electrode and the battery diaphragm according to claim 2 , wherein the battery diaphragm is positioned between the positive electrode and the negative electrode.
5 . The battery diaphragm according to claim 1 , wherein the vinylidene fluoride (VDF) polymer comprises a polyvinylidene fluoride homopolymer or a polyvinylidene fluoride copolymer.
6 . The battery diaphragm according to claim 1 , wherein the adhesive layer further comprises a filler.
7 . The battery diaphragm according to claim 1 , wherein the increase in the gas permeability per unit coating thickness of the adhesive layer is in a range between 11.4 s/100 cc/μm and 12.5 s/100 cc/μm.
8 . The battery diaphragm according to claim 1 , wherein the adhesive strength A of the adhesive layer is in a range between 6.3 N/m and 12.1 N/m.
9 . The battery diaphragm according to claim 1 , wherein the increase in the gas permeability per unit coating thickness of the adhesive layer is in a range between 11.4 s/100 cc/μm and 12.5 s/100 cc/μm and the adhesive strength A of the adhesive layer is in a range between 6.3 N/m and 12.1 N/m.
10 . The battery diaphragm according to claim 2 , wherein the vinylidene fluoride (VDF) polymer comprises a polyvinylidene fluoride homopolymer or a polyvinylidene fluoride copolymer.
11 . The battery diaphragm according to claim 2 , wherein the adhesive layer further comprises a filler.
12 . The battery diaphragm according to claim 2 , wherein the increase in the gas permeability per unit coating thickness of the adhesive layer is in a range between 11.2 s/100 cc/μm and 25.8 s/100 cc/μm.
13 . The battery diaphragm according to claim 2 , wherein the adhesive strength A of the adhesive layer is in a range between 6.5 N/m and 20.5 N/m.
14 . The battery diaphragm according to claim 2 , wherein the increase in the gas permeability per unit coating thickness of the adhesive layer is in a range between 11.2 s/100 cc/μm and 25.8 s/100 cc/μm and the adhesive strength A of the adhesive layer is in a range between 6.5 N/m and 20.5 N/m.