Detailed Description
To make the objects, technical solutions and advantages of the embodiments of the present invention clearer, the technical solutions of the present invention will be clearly and completely described below with reference to the accompanying drawings, and it is apparent that the described embodiments are some, but not all embodiments of the present invention. All other embodiments, which can be derived by a person skilled in the art from the embodiments given herein without making any creative effort, shall fall within the protection scope of the present invention.
A first part:
the gel coating in the traditional gel coating diaphragm is not easy to be soaked by electrolyte in the battery due to poor oleophylic capability, so that the aging time of the lithium battery is long, and the production efficiency of the battery is reduced. In order to improve the oleophilic capacity of PVDF (polyvinylidene fluoride), the invention provides a PVDF gluing membrane, which comprises: the PVDF glue coating layer is positioned on the surface of the base film; wherein the PVDF rubber coating layer comprises the following raw materials: PVDF sizing agent, cross-linking agent, macromolecular material containing oleophylic group; and under the catalytic action, the polymer material and the PVDF slurry generate a crosslinking reaction through a crosslinking agent so as to graft the oleophilic group on the PVDF slurry.
Optionally, the base film includes, but is not limited to, high polymer films such as PP film, PE film, PI film, PET film, and the like, and composite films thereof. And the catalysis comprises illumination at a wavelength of 350 nm.
Specifically, the reaction formula of the crosslinking reaction of the PVDF slurry, the crosslinking agent and the polymer material containing the oleophylic group is as follows:
wherein the structural formula of the high polymer material is
R is a hydrocarbon chain;
the structural formula of the oleophilic group is as follows:
the structural formula of the cross-linking agent is as follows:
and
the structural formula of PVDF is:
the structural formula of the finally generated PVDF gummed layer is shown as
From the above reaction formula, under the catalysis of illumination, the polymer material and the PVDF slurry undergo a cross-linking reaction through the cross-linking agent, the oleophilic group is grafted on the PVDF slurry, and then the wettability of the PVDF to the electrolyte is increased through the oleophilic group.
As an alternative embodiment to PVDF slurries.
The PVDF sizing agent comprises the following raw materials: PVDF colloidal particles, a dispersing agent, a wetting agent, a binder, a defoaming agent, an anti-settling agent and water; and the mass ratio of each component is 1: (0.04-0.11): (0.004-0.010): (0.12-0.53): (0.052-0.34): (0.011-0.32): (3-16).
Optionally, PVDF colloidal particles, a dispersing agent, a wetting agent, a binder, a defoaming agent, an anti-settling agent and water; and the mass ratio of each component is 1: 0.8: 0.006: 0.3: 0.1: 0.2: 10.
optionally, PVDF colloidal particles, a dispersing agent, a wetting agent, a binder, a defoaming agent, an anti-settling agent and water; and the mass ratio of each component is 1: 0.2: 0.008: 0.45: 0.2: 0.08: 6.
wherein:
the dispersing agent comprises silicate (such as water glass), alkali metal phosphate (such as sodium tripolyphosphate, sodium hexametaphosphate, sodium pyrophosphate and the like), and organic dispersing agent; the organic dispersant includes: at least one of triethylhexyl phosphoric acid, sodium dodecyl sulfate, methyl amyl alcohol, cellulose derivative, polyacrylamide, Gule gum and fatty acid polyglycol ester.
The wetting agent includes, but is not limited to, at least one of anionic and nonionic surfactants and the like.
The binder includes, but is not limited to, an acrylic-type binder.
The defoaming agent comprises but is not limited to emulsified silicone oil, high alcohol fatty acid ester compound, polyoxyethylene polyoxypropylene pentaerythritol ether, polyoxyethylene polyoxypropylene amine ether, polyoxypropylene glycerol ether, polyoxypropylene polyoxyethylene glycerol ether, polydimethylsiloxane and the like, or a combination of a plurality of materials.
The anti-settling agent comprises at least one of but not limited to solvent-based rheological additive, solvent-free rheological additive, novel rheological additive (German Bick BYK410) and the like.
As described above, referring to fig. 1, the present invention also provides a method for preparing a PVDF rubberized membrane, comprising: preparing PVDF slurry; coating PVDF slurry on a base film; spraying a cross-linking agent; spraying a high polymer material containing lipophilic groups; and (3) catalyzing to enable the high polymer material and the PVDF slurry to generate a crosslinking reaction, namely grafting the oleophylic group on the PVDF slurry.
As mentioned above, the invention also provides a PVDF glue coating layer, which comprises the following raw materials: PVDF sizing agent, cross-linking agent, macromolecular material containing oleophylic group; the polymer material is suitable for carrying out a crosslinking reaction with PVDF slurry under the catalysis action so as to graft lipophilic groups on the PVDF slurry to form a PVDF glue coating layer, and the molecular structural formula of the PVDF glue coating layer is as follows:
wherein R is a hydrocarbon chain.
As described above, the present invention also provides a lithium battery including: a diaphragm; the membrane was a PVDF rubberized membrane as described previously.
A second part:
example 1
Firstly, adding 5.1kg of dispersing agent into 310kg of water, and stirring and dispersing for 30 min; then 0.65kg of wetting agent is added, and stirring and dispersion are carried out for 30 min; then adding 12kg of defoaming agent and 3.6kg of anti-settling agent, and stirring and dispersing for 30 min; dissolving 100kg of PVDF in the stirred solution, and performing sand grinding or mechanical dispersion until the dispersion is uniform; adding 45kg of binder into the uniformly dispersed solution, and stirring and dispersing for 60min to prepare PVDF slurry;
selecting a PE film with the thickness of 12 micrometers as a base film, and coating a diaphragm by micro gravure coating, wherein the thickness of the coating is 2 micrometers;
then spraying a layer of cross-linking agent with the thickness of 0.2 mu m;
then spraying a layer of 0.1 mu m thick polymer material containing oleophilic groups;
after spraying, illumination with the wavelength of 350nm is used, and crosslinking reaction is carried out on the PVDF and the macromolecule containing oleophylic groups;
and after the reaction is completed, carrying out rolling operation to obtain the PVDF gluing diaphragm.
Example 2
Firstly, adding 11kg of triethyl hexyl phosphoric acid into 1600kg of water, and stirring and dispersing for 30 min; then 0.4kg of nonionic surfactant is added, and stirring and dispersing are carried out for 30 min; then adding 5.2kg of emulsified silicone oil and 1.1kg of solvent type rheological additive, and stirring and dispersing for 30 min; dissolving 100kg of PVDF in the stirred solution, and performing sand grinding or mechanical dispersion until the dispersion is uniform; adding 53kg of acrylic acid type binder into the uniformly dispersed solution, and stirring and dispersing for 60min to prepare PVDF slurry;
selecting a PET film with the thickness of 12 microns as a base film, and coating a diaphragm by micro gravure coating, wherein the thickness of the coating is 2 microns;
then spraying a layer of cross-linking agent with the thickness of 0.2 mu m;
then spraying a layer of 0.1 mu m thick polymer material containing oleophilic groups;
after spraying, illumination with the wavelength of 350nm is used, and crosslinking reaction is carried out on the PVDF and the macromolecule containing oleophylic groups;
and after the reaction is completed, carrying out rolling operation to obtain the PVDF gluing diaphragm.
Example 3
Firstly, adding 4kg of Guerban into 300kg of water, and stirring and dispersing for 30 min; then 1kg of anionic surfactant is added, and stirring and dispersing are carried out for 30 min; then 34kg of polydimethylsiloxane and 32kg of solvent-free rheological additive are added, and stirring and dispersing are carried out for 30 min; dissolving 100kg of PVDF in the stirred solution, and performing sand grinding or mechanical dispersion until the dispersion is uniform; adding 12kg of acrylic acid type binder into the uniformly dispersed solution, and stirring and dispersing for 60min to prepare PVDF slurry;
selecting a PI film with the thickness of 12 microns as a base film, and coating a diaphragm by micro gravure coating, wherein the thickness of the coating is 2 microns;
then spraying a layer of cross-linking agent with the thickness of 0.2 mu m;
then spraying a layer of 0.1 mu m thick polymer material containing oleophilic groups;
after spraying, illumination with the wavelength of 350nm is used, and crosslinking reaction is carried out on the PVDF and the macromolecule containing oleophylic groups;
and after the reaction is completed, carrying out rolling operation to obtain the PVDF gluing diaphragm.
Example 4
Firstly, adding 8kg of Guerban into 1000kg of water, and stirring and dispersing for 30 min; then 0.8kg of anionic surfactant is added, and stirring and dispersing are carried out for 30 min; then adding 15kg of polyoxypropylene glycerol ether and 20kg of solvent-free rheological additive, and stirring and dispersing for 30 min; dissolving 100kg of PVDF in the stirred solution, and performing sand grinding or mechanical dispersion until the dispersion is uniform; adding 35kg of acrylic acid type binder into the uniformly dispersed solution, and stirring and dispersing for 60min to prepare PVDF slurry;
selecting a PP film with the thickness of 12 micrometers as a base film, and coating a diaphragm by micro-gravure coating, wherein the thickness of the coating is 2 micrometers;
then spraying a layer of cross-linking agent with the thickness of 0.2 mu m;
then spraying a layer of 0.1 mu m thick polymer material containing oleophilic groups;
after spraying, illumination with the wavelength of 350nm is used, and crosslinking reaction is carried out on the PVDF and the macromolecule containing oleophylic groups;
and after the reaction is completed, carrying out rolling operation to obtain the PVDF gluing diaphragm.
Example 5
Referring to fig. 2, this example 5 performed a wet time test on the PVDF rubberized membrane (corresponding to the new model in fig. 2) prepared in example 1 and a conventional rubberized membrane (corresponding to the conventional one in fig. 2). It can be seen that the wetting time of the PVDF gummed membrane of the invention is 20 seconds, while the wetting time of the traditional membrane is 300 seconds, the wetting time of the PVDF gummed membrane is greatly shortened, which indicates that the wetting ability of the PVDF gummed membrane to the electrolyte is greatly improved, namely the oleophylic ability of the PVDF is improved. Of course, the wetting ability of the PVDF gumming membrane to the electrolyte is greatly improved, mainly because the oleophilic groups on the PVDF gumming membrane are grafted to the PVDF by the cross-linking agent, and then the wetting ability of the PVDF to the electrolyte is increased by using the oleophilic groups. Meanwhile, through the combination of chemical reaction and chemical bonds, the stability and the overall consistency of the PVDF gluing membrane are superior to those of the traditional gluing membrane.
In summary, according to the PVDF gumming diaphragm and the preparation method thereof, the PVDF gumming layer and the lithium battery, the lipophilic groups are grafted to the PVDF through the cross-linking agent, the wetting capacity of the PVDF to the electrolyte is improved by utilizing the lipophilic groups, and the stability and the overall consistency of the PVDF gumming diaphragm are superior to those of the traditional gumming diaphragm through the combination of chemical reaction and chemical bonds, so that the PVDF gumming diaphragm is more suitable for being applied to the lithium battery.
In light of the foregoing description of the preferred embodiment of the present invention, many modifications and variations will be apparent to those skilled in the art without departing from the spirit and scope of the invention. The technical scope of the present invention is not limited to the content of the specification, and must be determined according to the scope of the claims.