CN107591561A

CN107591561A - A kind of preparation method of lithium ion battery gel polymer electrolyte

Info

Publication number: CN107591561A
Application number: CN201710654387.6A
Authority: CN
Inventors: 向勇; 刘雯
Original assignee: University of Electronic Science and Technology of China
Current assignee: University of Electronic Science and Technology of China
Priority date: 2017-08-03
Filing date: 2017-08-03
Publication date: 2018-01-16

Abstract

The present invention relates to battery material preparation field, more particularly to a kind of preparation method of lithium ion battery gel polymer electrolyte.The present invention method for placing into coagulating bath immersion, solves by first handling PVDF HFP solution atomizations and occurs shrinkage, the phenomenon of surface irregularity in PVDF HFP solution film forming process.Gel polymer electrolyte film surfacing prepared by the present invention, improve effective usable floor area of dielectric film；And SEM is shown with smaller and uniformly intensive aperture, this is advantageous to the mechanical strength for strengthening dielectric film；With smaller interface impedance, the performance of battery is improved.

Description

A kind of preparation method of lithium ion battery gel polymer electrolyte

Technical field

The present invention relates to battery material preparation field, more particularly to a kind of system of lithium ion battery gel polymer electrolyte Preparation Method.

Background technology

Lithium ion battery is because with specific power is high, in light weight, operating voltage is high, energy density is big, small volume etc. is a series of Remarkable advantage and be used widely.Lithium ion battery is mainly made up of positive pole, electrolyte, negative pole.Existing lithium-ion electric Pond electrolyte, according to its Form division, liquid electrolyte, gel electrolyte, solid electrolyte can be divided into.Liquid electrolyte has Electrical conductivity is high, the advantages of widespread commercial；But its security is low, liquid leakage, blast etc. easily occurs.Solid electrolyte has Good security, but its electrical conductivity is low, can not also meet the requirement of commercial li-ion battery.

Gel polymer electrolyte is using high molecular polymer as matrix, and adds lithium salts and plasticizer on this basis, The electrolyte of the gel state formed.Gel polymer electrolyte had both possessed the high conductivity of liquid electrolyte, but also with solid-state The security of electrolyte, the advantages of having both concurrently.

It is to prepare a kind of common method of gel polymer electrolyte to soak the precipitation method.Polymer is dissolved in solvent first In, then polymer solution uniformly scratched on appropriate supporter, it is then immersed in the coagulating bath containing non-solvent and works as In, after solvent and non-solvent are exchanged with each other by Fick's law and reached to a certain degree, polymer occur liquid-liquid phase separation or Solid-liquid is separated, and turns into polymer-poor phase and polymer-rich phase.Turn into the main body of dielectric film after rich in polymers solidifying, And polymer-poor phase then turns into the micropore of film, electrolytic thin-membrane is obtained.Then, electrolytic thin-membrane is soaked gel in the electrolytic solution Change, just obtain can be applicable to the gel polymer electrolyte of lithium ion battery.

During the immersion precipitation method prepare gel electrolyte, it is necessary and important to soak the coagulating bath containing non-solvent Film formation step.In preparation process, uniformly blade coating gathers after one piece of the polymer solution and supporter of supporter are put into coagulating bath Polymer solution carries out liquid-liquid phase separation or solid-liquid is separated, and polymer film-forming, is come off from supporter, floats and solidifying In bath.But its dielectric film prepared, because of its surface irregularity, the availability that dielectric film is used for assembled battery is low, and meeting Cause the interface resistance between electrolyte and cell positive material to increase, and then influence performance of lithium ion battery.

The content of the invention

Problem or deficiency be present for above-mentioned, to overcome the immersion precipitation method to prepare in gel polymer electrolyte, it is prepared Dielectric film curling, the technical problem of surface irregularity.The invention provides a kind of electrolysis of lithium ion battery gel polymer The preparation method of matter.

Specific method of the present invention, comprises the following steps：

Step 1, prepare PVDF-HFP (polyvinylidenefluoride-hexafluoropropylene, poly- inclined fluorine Ethene-hexafluoropropylene copolymer) solution, consisting of PVDF-HFP, pore former and solvent mixed solution；

The PVDF-HFP：Pore former：The mass percent of solvent is (8-10)：(0-5)：(80-95)；Pore former is poly- Vinylpyrrolidone and/or urea；Solvent is DMAC N,N' dimethyl acetamide, N,N-dimethylformamide and/or N- methylpyrroles Alkanone.

Step 2, the PVDF-HFP solution for preparing step 1 are uniformly scratched on supporter；The supporter be glass plate, Polyfluortetraethylene plate, aluminium foil or copper foil.

Step 3, at the PVDF-HFP solution surfaces 20-50cm coated on supporter, using PVDF-HFP solution Non-solvent to its atomization process, non-solvent is uniformly sprayed at PVDF-HFP solution surfaces, until PVDF-HFP solution film formings Come off, i.e., come off after solidification for electrolyte film forming from supporter.

Step 4, the dielectric film that step 3 comes off from supporter, which are put into the coagulating bath of non-solvent used in step 3, to be soaked Bubble, makes it remove pore former and solvent completely；Then dielectric film is taken out from coagulating bath, is put into 40- in vacuum drying chamber 80 DEG C of dryings.

Step 5, the dried dielectric film of step 4 is immersed in electrolyte and soaks at least 2h, make its gel activate to obtain Gel polymer electrolyte.

Further, atomization process is carried out from spray bottle sprinkling, atomizer or humidifier in the step 3.

The existing immersion precipitation method, because of polymer solution Rapid contact coagulating bath composition, liquid-liquid phase separation or solid-liquid phase Separation is swift in response acutely, and polymer rapid curing film forming, obtained dielectric film crimps more, phenomena such as out-of-flatness, electricity The pattern of solution plasma membrane is difficult to effectively control.

The present invention method for placing into coagulating bath immersion, solves PVDF- by first handling PVDF-HFP solution atomizations Occur shrinkage, the phenomenon of surface irregularity in HFP solution film forming process.Compared with existing directly immersion coagulating bath, present invention system Standby gel polymer electrolyte film surfacing, improve effective usable floor area of dielectric film；And SEM is shown with smaller And uniform intensive aperture, this is advantageous to the mechanical strength for strengthening dielectric film；With smaller interface impedance, battery is improved Performance.

Brief description of the drawings

Fig. 1 is prior art, and PVDF-HFP solution soaks the preparation process of coagulating bath film-forming；

Fig. 2 is the preparation process of embodiment；

Fig. 3 (a) is dielectric film pictorial diagram made from prior art；(b) it is dielectric film pictorial diagram made from embodiment；

Fig. 4 (a) is dielectric film SEM (ESEM) made from prior art；(b) it is dielectric film made from embodiment SEM；

Fig. 5：The EIS contrast collection of illustrative plates of dielectric film prepared by dielectric film and embodiment prepared by prior art；

Reference：1-PVDF-HFP solution, 2- supporters, 3- deionized waters, 4- coagulating bath containers, 5- spray bottles.

Embodiment

The present invention is described in further detail in conjunction with the accompanying drawings and embodiments.

Step 1, according to 10wt%PVDF-HFP:5wt%PVP:85wt%DMAC mass ratio prepares PVDF-HFP solution；

Step 2, step 1 is prepared to the uniform blade coating of the PVDF-HFP solution being uniformly dissolved on aluminium foil；

Step 3, at the PVDF-HFP solution surfaces 50cm coated apart from aluminium foil, with the spray bottle for filling deionized water, Deionized water is uniformly sprayed in PVDF-HFP solution surfaces, treat that it slowly occurs solid-liquid and is separated, gentle film forming, until Come off after solidification for electrolyte film forming from aluminium foil；

Step 4, the dielectric film to come off is put into deionized water and soaked, it is removed pore former and solvent completely；So Dielectric film is taken out from deionized water afterwards, is put into 60 DEG C of dry 10h in vacuum drying chamber；

Step 5, the dried dielectric film of step 4 immersed 1mol/L LiPF₆EC/DEC electrolyte in soak 2h, Its gel is set to activate to obtain gel polymer electrolyte.

Using above-mentioned the same terms, gel polymer electrolyte is prepared with the existing immersion precipitation method, with the present embodiment Contrast.

The gel polymer electrolyte surfacing (as shown in Figure 3 b) that the present embodiment obtains, shrinkage degree is significantly lower than existing There is dielectric film (as shown in Figure 3 a) prepared by technology；The micropore of dielectric film is evenly distributed, and institute is smaller into micropore size, and causes Close (as shown in Figure 4 b), the mechanical strength of dielectric film is improved indirectly；Contrasted by Fig. 5 EIS collection of illustrative plates, prepared by the present invention The interface impedance of dielectric film and positive electrode is about in 600ohms, hence it is evident that less than prior art dielectric film interface impedance 680ohms。

Claims

1. a kind of preparation method of lithium ion battery gel polymer electrolyte, comprises the following steps：

Step 1, prepare PVDF-HFP Kynoar-hexafluoropropylene copolymer solution, consisting of PVDF-HFP, pore former and The mixed solution of solvent；

The PVDF-HFP：Pore former：The mass percent of solvent is (8-10)：(0-5)：(80-95)；Pore former is polyethylene Pyrrolidones and/or urea；Solvent is DMAC N,N' dimethyl acetamide, N,N-dimethylformamide and/or 1-METHYLPYRROLIDONE；

Step 2, the PVDF-HFP solution for preparing step 1 are uniformly scratched on supporter；

Step 3, at the PVDF-HFP solution surfaces 20-50cm coated on supporter, using the non-of PVDF-HFP solution Solvent makes non-solvent uniformly be sprayed at PVDF-HFP solution surfaces its atomization process, until PVDF-HFP solution film formings come off, Come off after solidification for electrolyte film forming from supporter；

Step 4, the dielectric film that step 3 comes off from supporter, which are put into the coagulating bath of non-solvent used in step 3, to be soaked, and is made It removes pore former and solvent completely；Then dielectric film is taken out from coagulating bath, be put into vacuum drying chamber 40-80 DEG C it is dry It is dry；

Step 5, the dried dielectric film of step 4 is immersed in electrolyte and soaks at least 2h, make its gel activate to obtain gel Polymer dielectric.

2. the preparation method of lithium ion battery gel polymer electrolyte as claimed in claim 1, it is characterised in that：The step Atomization process is carried out from spray bottle sprinkling, atomizer or humidifier in 3.

3. the preparation method of lithium ion battery gel polymer electrolyte as claimed in claim 1, it is characterised in that：The support Body is glass plate, polyfluortetraethylene plate, aluminium foil or copper foil.