Preparation method of lithium battery diaphragm special for solid electrolyte
阅读说明：本技术 固态电解质专用锂电池隔膜的制备方法 (Preparation method of lithium battery diaphragm special for solid electrolyte ) 是由 胡伟 何祥燕 吴磊 张德顺 李汪洋 徐凤锦 孙小华 郭浩 贺云 朱景龙 王瑞 于 2020-12-07 设计创作，主要内容包括：本发明公开了一种固态电解质专用锂电池隔膜的制备方法,涉及锂电池隔膜技术领域,本发明通过对聚乙烯醇的接枝改性制得改性聚乙烯醇并作为成膜剂,利用其成膜作用实现纳米二氧化钛和氢化钇在基膜上的均匀分布与固着,同时控制隔膜的微孔尺寸,避免常规成膜剂影响隔膜的透过性能,最终制得的隔膜适用于作为固态电解质专用锂电池隔膜,离子电导率高,并强化了锂电池的安全使用性。(The invention discloses a preparation method of a lithium battery diaphragm special for solid electrolyte, which relates to the technical field of lithium battery diaphragms.)
1. The preparation method of the lithium battery diaphragm special for the solid electrolyte is characterized by comprising the following steps: the method comprises the following steps:
(1) heating polyvinyl alcohol to a molten state, adding 5- (tert-butyl) furan-2-carboxylic acid for a melting reaction, cooling a reactant after the reaction is finished, washing with hot water, filtering, and drying to obtain modified polyvinyl alcohol;
(2) dissolving the modified polyvinyl alcohol prepared in the step (1) in an organic solvent, adding nano titanium dioxide and yttrium hydride, and heating and stirring to obtain yttrium hydride doped titanium sol;
(3) and (3) coating the yttrium hydride doped titanium sol prepared in the step (2) on the surface of the base film, and drying to obtain the lithium battery diaphragm.
2. The method for preparing a separator for a lithium battery dedicated for a solid electrolyte according to claim 1, wherein: the dosage ratio of the polyvinyl alcohol to the 5- (tert-butyl) furan-2-carboxylic acid is 100: 20-50.
3. The method for preparing a separator for a lithium battery dedicated for a solid electrolyte according to claim 1, wherein: the temperature of the melting reaction is 240-250 ℃.
4. The method for preparing a separator for a lithium battery dedicated for a solid electrolyte according to claim 1, wherein: the organic solvent is one of N-methyl pyrrolidone, N-dimethylformamide, N-dimethylacetamide and dimethyl sulfoxide.
5. The method for preparing a separator for a lithium battery dedicated for a solid electrolyte according to claim 1, wherein: the dosage ratio of the nano titanium dioxide, the modified polyvinyl alcohol, the yttrium hydride and the organic solvent is 100:5-20:0.5-5: 50-100.
6. The method for preparing a separator for a lithium battery dedicated for a solid electrolyte according to claim 1, wherein: the base film is a polyethylene film or a polypropylene film.
7. The method for preparing a separator for a lithium battery dedicated for a solid electrolyte according to claim 1, wherein: the thickness of the base film is 5-10 μm.
8. The method for preparing a separator for a lithium battery dedicated for a solid electrolyte according to claim 1, wherein: the coating thickness of the yttrium hydride doped titanium sol is 0.5-3 μm.
The technical field is as follows:
the invention relates to the technical field of lithium battery diaphragms, in particular to a preparation method of a lithium battery diaphragm special for solid electrolyte.
Background art:
in the construction of lithium batteries, the separator is one of the key internal layer components. The performance of the diaphragm determines the interface structure, internal resistance and the like of the battery, directly influences the capacity, circulation, safety performance and other characteristics of the battery, and the diaphragm with excellent performance plays an important role in improving the comprehensive performance of the battery. The separator has a main function of separating the positive electrode and the negative electrode of the battery to prevent short circuit due to contact between the two electrodes, and also has a function of allowing electrolyte ions to pass therethrough.
In the past, most of the research on batteries focused on liquid electrolyte systems, which have poor electrochemical and thermal stability, low ion selectivity, and poor safety, even though they have excellent conductivity and electrode surface wettability. The replacement of liquid electrolytes with solid electrolytes not only overcomes the problem of electrolyte permanence, but also provides the possibility for developing new chemical batteries. Research proves that the thickness of the solid electrolyte needs to be reduced when the ionic conductivity is improved, but the electrolyte is directly contacted with the positive electrode and the negative electrode, and if the electrolyte is too thin and does not completely cover the positive electrode and the negative electrode, potential safety hazards are formed.
The invention content is as follows:
the technical problem to be solved by the invention is to provide a preparation method of a lithium battery diaphragm special for a solid electrolyte, which not only designs and prepares modified polyvinyl alcohol, but also uses the modified polyvinyl alcohol as a film forming agent to ensure that nano titanium dioxide and yttrium hydride are uniformly distributed on the surface of the diaphragm, so as to improve the ionic conductivity of the diaphragm and solve the problem that the conventional polymer film forming agent affects the ionic conductivity of the diaphragm.
The technical problem to be solved by the invention is realized by adopting the following technical scheme:
the preparation method of the lithium battery diaphragm special for the solid electrolyte comprises the following steps:
(1) heating polyvinyl alcohol to a molten state, adding 5- (tert-butyl) furan-2-carboxylic acid for a melting reaction, cooling a reactant after the reaction is finished, washing with hot water, filtering, and drying to obtain modified polyvinyl alcohol;
(2) dissolving the modified polyvinyl alcohol prepared in the step (1) in an organic solvent, adding nano titanium dioxide and yttrium hydride, and heating and stirring to obtain yttrium hydride doped titanium sol;
(3) and (3) coating the yttrium hydride doped titanium sol prepared in the step (2) on the surface of the base film, and drying to obtain the lithium battery diaphragm.
The dosage ratio of the polyvinyl alcohol to the 5- (tert-butyl) furan-2-carboxylic acid is 100: 20-50.
The polyvinyl alcohol and the 5- (tert-butyl) furan-2-carboxylic acid are subjected to esterification reaction in a molten state, a reaction solvent and a dehydrating agent are not used, although the energy consumption of the reaction is high, the investment cost of the reaction solvent is reduced, and the water generated by the esterification reaction is instantly volatilized due to high reaction temperature, so that the forward progress of the reaction is promoted, and concentrated sulfuric acid is not required to be added as the dehydrating agent.
The prepared modified polyvinyl alcohol is used as a film forming agent, so that the uniform distribution and fixation of the nano titanium dioxide and the yttrium hydride on the base film are realized, and compared with the conventional polyvinyl alcohol, the prepared modified polyvinyl alcohol has better affinity to the nano titanium dioxide, the yttrium hydride and the base film, and is beneficial to improving the application performance of the diaphragm.
The temperature of the melting reaction is 240-250 ℃.
The organic solvent is one of N-methyl pyrrolidone, N-dimethylformamide, N-dimethylacetamide and dimethyl sulfoxide.
The dosage ratio of the nano titanium dioxide, the modified polyvinyl alcohol, the yttrium hydride and the organic solvent is 100:5-20:0.5-5: 50-100.
The base film is a polyethylene film or a polypropylene film.
The thickness of the base film is 5-10 μm.
The coating thickness of the yttrium hydride doped titanium sol is 0.5-3 μm.
The invention has the beneficial effects that: according to the invention, the modified polyvinyl alcohol is prepared by graft modification of polyvinyl alcohol and is used as a film forming agent, the uniform distribution and fixation of nano titanium dioxide and yttrium hydride on a base film are realized by utilizing the film forming effect of the modified polyvinyl alcohol, the micropore size of the diaphragm is controlled, the influence of the conventional film forming agent on the permeability of the diaphragm is avoided, the finally prepared diaphragm is suitable for being used as a special lithium battery diaphragm for a solid electrolyte, the ionic conductivity is high, and the safety use of the lithium battery is enhanced.
The specific implementation mode is as follows:
in order to make the technical means, the creation characteristics, the achievement purposes and the effects of the invention easy to understand, the invention is further described with the specific embodiments.
Polyvinyl alcohol was purchased from clony PVA217 SB.
The polyethylene base film is purchased from a polyethylene diaphragm with the thickness of 10 mu m of Texas auspicious environment-friendly new material company Limited.
The nano titanium dioxide is purchased from Shanghai Kay chemical company Limited, and the average grain diameter is 20 nm.
The solid electrolyte was purchased from TP-3100, Youqia (Shanghai) International trade company, Inc.
Example 1
(1) Heating 10g of polyvinyl alcohol to a molten state, adding 3.8g of 5- (tert-butyl) furan-2-carboxylic acid, carrying out a melting reaction for 3 hours at 250 ℃, cooling the reaction product after the reaction is finished, washing for 3 times by adopting hot water at 95 ℃, filtering, and drying to obtain the modified polyvinyl alcohol. FT-IR infrared spectrum analysis of the product at 1735cm-1The peak appears in the ester group, and the C ═ O stretching vibration absorption peak is 1172cm-1A C-O stretching vibration absorption peak in the ester group appears.
(2) And (2) dissolving 10g of the modified polyvinyl alcohol prepared in the step (1) in 80g N N-dimethylformamide, adding 100g of nano titanium dioxide and 2g of yttrium hydride, heating to 80 ℃, and stirring for 30min to obtain yttrium hydride doped titanium sol.
(3) And (3) coating the yttrium hydride doped titanium sol prepared in the step (2) on the surface of the base film, coating the yttrium hydride doped titanium sol to a thickness of 2.5 mu m, and drying to obtain the lithium battery diaphragm.
Example 2
Example 2 the same procedure as in example 1 was used to prepare a separator, except that the amount of nano titanium dioxide added was adjusted.
(1) Heating 10g of polyvinyl alcohol to a molten state, adding 3.8g of 5- (tert-butyl) furan-2-carboxylic acid, carrying out a melting reaction for 3 hours at 250 ℃, cooling the reaction product after the reaction is finished, washing for 3 times by adopting hot water at 95 ℃, filtering, and drying to obtain the modified polyvinyl alcohol.
(2) And (2) dissolving 10g of the modified polyvinyl alcohol prepared in the step (1) in 80g N N-dimethylformamide, adding 90g of nano titanium dioxide and 2g of yttrium hydride, heating to 80 ℃, and stirring for 30min to obtain yttrium hydride doped titanium sol.
(3) And (3) coating the yttrium hydride doped titanium sol prepared in the step (2) on the surface of the base film, coating the yttrium hydride doped titanium sol to a thickness of 2.5 mu m, and drying to obtain the lithium battery diaphragm.
Example 3
Example 3 the same procedure as in example 1 was repeated except that the amount of yttrium hydride to be added was adjusted.
(1) Heating 10g of polyvinyl alcohol to a molten state, adding 3.8g of 5- (tert-butyl) furan-2-carboxylic acid, carrying out a melting reaction for 3 hours at 250 ℃, cooling the reaction product after the reaction is finished, washing for 3 times by adopting hot water at 95 ℃, filtering, and drying to obtain the modified polyvinyl alcohol.
(2) And (2) dissolving 10g of the modified polyvinyl alcohol prepared in the step (1) in 80g N N-dimethylformamide, adding 100g of nano titanium dioxide and 1g of yttrium hydride, heating to 80 ℃, and stirring for 30min to obtain yttrium hydride doped titanium sol.
(3) And (3) coating the yttrium hydride doped titanium sol prepared in the step (2) on the surface of the base film, coating the yttrium hydride doped titanium sol to a thickness of 2.5 mu m, and drying to obtain the lithium battery diaphragm.
Comparative example 1
Comparative example 1 was the same as example 1 except that yttrium hydride was not added, and a separator was prepared.
(1) Heating 10g of polyvinyl alcohol to a molten state, adding 3.8g of 5- (tert-butyl) furan-2-carboxylic acid, carrying out a melting reaction for 3 hours at 250 ℃, cooling the reaction product after the reaction is finished, washing for 3 times by adopting hot water at 95 ℃, filtering, and drying to obtain the modified polyvinyl alcohol.
(2) And (2) dissolving 10g of the modified polyvinyl alcohol prepared in the step (1) in 80g N N-dimethylformamide, adding 100g of nano titanium dioxide, heating to 80 ℃, and stirring for 30min to obtain yttrium hydride doped titanium sol.
(3) And (3) coating the yttrium hydride doped titanium sol prepared in the step (2) on the surface of the base film, coating the yttrium hydride doped titanium sol to a thickness of 2.5 mu m, and drying to obtain the lithium battery diaphragm.
Comparative example 2
Comparative example 2 the same procedure as in example 1 was conducted except that polyvinyl alcohol was used instead of the modified polyvinyl alcohol to prepare a separator.
(1) 10g of polyvinyl alcohol is dissolved in 80g N, N-dimethylformamide, 100g of nano titanium dioxide and 2g of yttrium hydride are added, the mixture is heated to 80 ℃ and stirred for 30min, and yttrium hydride doped titanium sol is obtained.
(2) And (3) coating the yttrium hydride doped titanium sol prepared in the step (2) on the surface of the base film, coating the yttrium hydride doped titanium sol to a thickness of 2.5 mu m, and drying to obtain the lithium battery diaphragm.
And (3) forming a model battery according to the stainless steel electrode/diaphragm + solid electrolyte/stainless steel electrode, measuring alternating current impedance, and calculating the ionic conductivity according to a formula.
Ionic conductivity is diaphragm thickness/(AC impedance value X contact area of electrode and diaphragm)
The results are shown in Table 1.
TABLE 1
Group of
Ionic conductivity (S.cm)-1)
Example 1
5.7×10-2
Example 2
4.5×10-2
Example 3
4.8×10-2
Comparative example 1
4.0×10-2
Comparative example 2
1.1×10-2
As can be seen from table 1, the ionic conductivity of the lithium battery separator prepared in the examples of the present invention is greatly improved by adding yttrium hydride, nano titanium dioxide and modified polyvinyl alcohol.
The foregoing shows and describes the general principles and broad features of the present invention and advantages thereof. It will be understood by those skilled in the art that the present invention is not limited to the embodiments described above, which are described in the specification and illustrated only to illustrate the principle of the present invention, but that various changes and modifications may be made therein without departing from the spirit and scope of the present invention, which fall within the scope of the invention as claimed. The scope of the invention is defined by the appended claims and equivalents thereof.