Self-stabilized P(VDF-HFP) (Poly(Vinylidene Fluoride-Hexafluoropropylene)) slurry as well as preparation and lithium-ion battery separator thereof

Abstract

The invention discloses a preparation method of self-stabilized P(VDF-HFP) (Poly(Vinylidene Fluoride-Hexafluoropropylene)) slurry. The preparation method comprises the following steps: adding an acrylic monomer and a polymerization inhibitor into deionized water for mixing and dissolving, and further adding P(VDF-HFP) powder to obtain a mixed system; introducing an inert gas into the mixed systemto eliminate air in the mixed system, and sealing and preserving later; putting the mixed system which is sealed and preserved in the step b into a 60COgamma-ray radiation chamber for radiation to obtain dispersion liquid; centrifuging the dispersion liquid, washing with water, and re-dispersing the dispersion liquid into deionized water to obtain the self-stabilized P(VDF-HFP) slurry. According to the slurry prepared by the invention, no surfactant or adhesive is required to be added, performance degradation and hidden danger caused by dissolving of the surfactant or the adhesive in electrolyte can be avoided when coating a lithium-ion battery separator with the slurry, so that the performance and the security properties of a lithium-ion battery are substantially improved.

Description

technical field [0001] The invention relates to the field of lithium-ion battery separators, in particular to a self-stabilizing P(VDF-HFP) slurry and a preparation method thereof, and also to a lithium-ion battery separator. Background technique [0002] In recent years, with the rise of new energy vehicles as an emerging strategic industry, power lithium-ion batteries with high energy density, excellent safety, and excellent cruising range have attracted more and more attention. As one of the four key main materials of lithium-ion batteries (positive electrode, negative electrode, diaphragm, and electrolyte), the separator mainly plays the role of isolating the positive and negative electrodes and allowing lithium ions to pass freely. Although the separator does not participate in the electrochemical reaction in the battery, it directly affects the capacity, cycle performance and safety performance of the battery. With the improvement of battery energy density, especially...

AI Technical Summary

Problems solved by technology

Although this method has certain advantages, there are also many defects. On the one hand, the hydrogen bonds formed in the P(VDF-HFP) molecular chain are very strong, and the electronegativity of oxygen in water is not enough to separate the hydrogen bonds, resulting in P(VDF-HFP) is basically not dispersed in water, so a surfactant needs to be added to reduce the surface tension of water and increase the surface free energy of P(VDF-HFP); on the other hand, a binder needs to be added to the slurry to Realize the bonding between P(VDF-HFP) and polyolefin separator to prevent powder falling

However, the introduction of surfactants and binders may dissolve under the long-term infiltration of the electrolyte, which poses potential safety hazards to the consistency of the battery, especially the safety.

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