CN115911529A - Composite garnet type solid electrolyte, secondary battery and preparation method - Google Patents
Composite garnet type solid electrolyte, secondary battery and preparation method Download PDFInfo
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- CN115911529A CN115911529A CN202211728530.9A CN202211728530A CN115911529A CN 115911529 A CN115911529 A CN 115911529A CN 202211728530 A CN202211728530 A CN 202211728530A CN 115911529 A CN115911529 A CN 115911529A
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Abstract
The invention discloses a composite garnet type solid electrolyte, a secondary battery and a preparation method thereof, relating to the technical field of new energy. The composite garnet type solid electrolyte comprises a substrate and a coating film coated on the surface of the substrate, wherein the substrate is the garnet type solid electrolyte, and the coating film comprises polyethylene glycol and polyethylene oxide. Mixing organic solid electrolyte polyethylene oxide (PEO) and polyethylene glycol (PEG) in a certain proportion, and coating the mixture on the surface of the garnet-type solid electrolyte to form a coating film. PEG provides a plasticizing effect for PEO, reduces the crystallinity of PEO, improves the interface contact effect between the solid electrolyte and the electrode by the film coating, reduces the interface impedance, effectively improves the ionic conductivity of the matrix garnet solid electrolyte, and effectively improves the electrochemical performance of the solid battery by combining the PEO with the matrix garnet solid electrolyte.
Description
Technical Field
The invention relates to the technical field of new energy, in particular to a composite garnet type solid electrolyte, a secondary battery and a preparation method.
Background
In recent years, with the continuous development of science and technology, various electronic devices have become an indispensable part of people's lives, and the market share of electric vehicles has been gradually increased. The lithium ion battery has the characteristics of high energy density, large power density, wide working temperature range, long service life, no pollution to the environment and the like, and is widely applied to electronic products and electric automobiles. The mainstream lithium ion battery is a liquid lithium ion battery, and the adopted electrolyte has low melting point and is particularly easy to volatilize and burn, and in addition, the liquid lithium ion battery can be accompanied with the growth of lithium dendrites in the circulating use process, so that the performance of the battery is reduced, and the internal short circuit of the battery can be caused, even the explosion can occur. And the liquid lithium battery has large space occupation ratio and relatively low volume energy density.
The safety of the solid-state battery is better than that of the liquid-state battery. Compared with liquid electrolyte, the solid electrolyte is not easy to volatilize and leak and is not easy to burn, and in addition, the solid electrolyte can also effectively hinder the growth of lithium dendrite. Currently, a commonly used solid electrolyte is a garnet-type solid electrolyte. The garnet solid electrolyte has the advantages of high ionic conductivity, good chemical stability, wide electrochemical window and the like. However, the surface contact effect between the garnet-type solid electrolyte and the electrode is poor, and the interface impedance is large, resulting in poor battery performance.
Disclosure of Invention
The invention aims to solve the technical problems that the existing garnet type solid electrolyte has poor surface contact effect with an electrode, and interface impedance is large, so that the performance of a battery is poor.
In order to solve the above problem, in a first aspect, an embodiment of the present invention provides a composite garnet-type solid electrolyte, including a substrate and a coating film coated on a surface of the substrate, where the substrate is the garnet-type solid electrolyte, and the coating film includes polyethylene glycol and polyethylene oxide.
The further technical scheme is that in the coating, the mass percentage of polyethylene glycol is 10-20%.
The further technical proposal is that the garnet type solid electrolyte is Li a La 3 Zr b V c Y d O 12 Wherein a is 5 to 7; b is 1 to 2; c is 0 to 1; d is 0 to 1
The further technical proposal is that the thickness of the coating film is 10-20 um.
The further technical proposal is that the thickness of the substrate is 40-100 um.
The further technical scheme is that the molecular weight of the polyethylene glycol is 400-20000. The molecular weight is specifically a number average molecular weight.
The further technical scheme is that the molecular weight of the polyethylene oxide is 20000-10000000. The molecular weight is specifically a number average molecular weight.
In a second aspect, the present invention provides a method for preparing the composite garnet-type solid electrolyte according to the first aspect, comprising:
s1, preparing a matrix by a solid-phase method, wherein the matrix is garnet-type solid electrolyte;
s2, preparing mixed slurry of polyethylene glycol and polyethylene oxide, and coating the mixed slurry on the surface of the matrix in a film forming manner by adopting a hot pressing method to form a coating.
The further technical scheme is that in the coating, the mass percentage of polyethylene glycol is 10-20%.
In a second aspect, the present invention provides a secondary battery comprising the composite garnet-type solid electrolyte according to the first aspect.
Compared with the prior art, the invention can achieve the following technical effects:
mixing organic solid electrolyte polyethylene oxide (PEO) and polyethylene glycol (PEG) in a certain proportion, and coating the mixture on the surface of the garnet-type solid electrolyte to form a coating film. PEG provides a plasticizing effect for PEO, reduces the crystallinity of PEO, improves the interface contact effect between the solid electrolyte and the electrode by the film coating, reduces the interface impedance, effectively improves the ionic conductivity of the matrix garnet solid electrolyte, and effectively improves the electrochemical performance of the solid battery by combining the PEO with the matrix garnet solid electrolyte.
Drawings
In order to more clearly illustrate the technical solution of the present invention, the drawings needed to be used in the description of the embodiments are briefly introduced below, and it is obvious that the drawings in the following description are some embodiments of the present invention, and it is obvious for those skilled in the art to obtain other drawings based on these drawings without creative efforts.
FIG. 1 is a schematic structural view of a lithium reversible asymmetric cell prepared in example 1;
FIG. 2 is a schematic diagram of the structure of a symmetric battery with a gold inert blocking electrode prepared in example 1;
FIG. 3 is a graph showing the change of ion conductivity (. Sigma.) with temperature (T) of the composite garnet-type solid electrolyte prepared in example 1;
FIG. 4 is a graph showing the change of current with time measured by a direct current method for the symmetric battery with gold inert blocking electrode and the symmetric battery with lithium reversible electrode prepared in example 1;
fig. 5 is a graph of the cycle performance of the solid state lithium ion battery prepared in example 1.
Detailed Description
The technical solutions in the examples will be clearly and completely described below. It is apparent that the embodiments to be described below are only a part of the embodiments of the present invention, and not all of them. 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.
It will be understood that the terms "comprises" and/or "comprising," when used in this specification and the appended claims, specify the presence of stated features, integers, steps, operations, elements, and/or components, but do not preclude the presence or addition of one or more other features, integers, steps, operations, elements, components, and/or groups thereof.
It is also to be understood that the terminology used in the description of the invention herein is for the purpose of describing particular embodiments only and is not intended to be limiting of the invention. As used in the specification of the present invention and the appended claims, the singular forms "a," "an," and "the" are intended to include the plural forms as well, unless the context clearly indicates otherwise.
Example 1
Example 1 comprises the following steps:
(1) Preparation of garnet type solid electrolyte (Li) by solid phase method 7 La 3 Zr 1.2 V 0.4 Y 0.4 O 12 ) A substrate.
Taking LiOH and La which are raw materials required by preparing a matrix 2 O 3 、ZrO 2 、V 2 O 5 、Y 2 O 3 The mixing ratio of Li: la: zr: V: Y = 7. And putting the sieved mixed powder into a muffle furnace to be calcined for 9 hours at 1100 ℃ to form solid electrolyte matrix powder, sending the solid electrolyte matrix powder into a ball milling tank to be ball milled for 10 hours at the rotating speed of 350rpm, and sieving by a sieve of 100 meshes again.
And (3) putting the sieved fine powder into a tabletting machine for tabletting treatment, and then, sending the powder into a muffle furnace for sintering for 2.5 hours at 1200 ℃ to obtain a garnet-type solid electrolyte matrix with the thickness of 80um. After cooling, the surface of the steel plate is finely ground to be flat.
(2) Preparing mixed slurry of polyethylene glycol and polyethylene oxide, and coating the mixed slurry on the surface of the matrix by adopting a hot pressing method to form a film so as to form a coating.
Weighing polyethylene oxide (PEO) and polyethylene glycol (PEG) in a mass ratio of 8. The mixed slurry is heated to 75 ℃ to be fully melted, then the mixed slurry is cooled to 60 ℃, and the mixed slurry is coated on the surface of a garnet solid electrolyte matrix to form a coating film through a hot pressing method, so that the composite garnet solid electrolyte is prepared. Wherein the average thickness of the coating film is 15um.
(3) Preparation of symmetrical Battery
And (3) sandwiching the composite garnet type solid electrolyte between two lithium sheets, and cold pressing to form the lithium reversible electrode symmetrical battery. The structure of the lithium reversible electrode symmetric cell is shown in fig. 1. In fig. 1, 10 denotes a garnet-type solid electrolyte matrix, 20 denotes a coating film, and 30 denotes a lithium plate.
And sputtering a gold (Au) electrode on the composite garnet type solid electrolyte by a magnetron sputtering method to form the gold inert blocking electrode symmetrical battery. The structure of the gold inert blocking electrode symmetrical battery is shown in figure 2. In fig. 2, 10 denotes a garnet-type solid electrolyte matrix, 20 denotes a coating film, and 30 denotes a gold layer.
(4) The conductivity of the gold inert blocking electrode symmetric battery prepared by the method is tested by an alternating current impedance method, and the test result is shown in fig. 3. The test result shows that the ionic conductivity of the composite garnet solid electrolyte reaches 8.71 multiplied by 10 at the temperature of 30 DEG C -4 S/cm。
(5) The ionic conductivity and the electronic conductivity of the composite garnet-type solid electrolyte were measured and indirectly compared by a direct current method using a symmetric cell with a gold inert blocking electrode and a symmetric cell with a lithium reversible electrode, and the results of the measurements are shown in fig. 4. The result shows that the stable current of the symmetric battery with the gold inert blocking electrode is 4 orders of magnitude lower than that of the symmetric battery with the lithium reversible electrode, and the electronic conductivity of the composite garnet solid electrolyte is far lower than the ionic conductivity.
(6) Preparation of solid lithium ion battery
The composite garnet type solid electrolyte, lithium iron phosphate (anode) and metallic lithium (cathode) are assembled into a solid lithium ion battery, the battery is subjected to cycle performance test, and the test result shows that the capacity retention rate of the battery is 88% after 100 charge-discharge cycles. The cycle performance diagram of the solid-state lithium ion battery is shown in fig. 5.
Example 2
Example 2 comprises the following steps:
(1) Preparation of garnet-type solid electrolyte (Li) by solid-phase method 7 La 3 Zr 1 V 0.5 Y 0.5 O 12 ) A substrate.
Taking LiOH and La which are raw materials required by preparing a matrix 2 O 3 、ZrO 2 、V 2 O 5 、Y 2 O 3 The mixing ratio of Li: la: zr: V: Y = 7. And putting the sieved mixed powder into a muffle furnace to be calcined for 9 hours at 1100 ℃ to form solid electrolyte matrix powder, feeding the solid electrolyte matrix powder into a ball milling tank to be ball milled for 10 hours at the rotating speed of 350rpm, and sieving by a sieve of 100 meshes again.
And (3) putting the sieved fine powder into a tabletting machine for tabletting treatment, and then, sending the powder into a muffle furnace for sintering for 2.5 hours at 1200 ℃ to obtain a garnet-type solid electrolyte matrix with the thickness of 80 microns. After cooling, the surface of the steel plate is finely ground to be flat.
(2) Preparing mixed slurry of polyethylene glycol and polyethylene oxide, and coating the mixed slurry on the surface of the matrix by adopting a hot pressing method to form a film so as to form a coating.
Weighing polyethylene oxide (PEO) and polyethylene glycol (PEG) in a mass ratio of 8. The mixed slurry is heated to 75 ℃ to be fully melted, then the mixed slurry is cooled to 60 ℃, and the mixed slurry is coated on the surface of a garnet solid electrolyte matrix to form a coating film through a hot pressing method, so that the composite garnet solid electrolyte is prepared. Wherein the average thickness of the coating is 15um.
(3) Preparation of symmetrical Battery
And (3) sandwiching the composite garnet type solid electrolyte between two lithium sheets, and cold pressing to form the lithium reversible electrode symmetrical battery.
And sputtering a gold (Au) electrode on the composite garnet type solid electrolyte by a magnetron sputtering method to form the gold inert blocking electrode symmetrical battery.
(4) The conductivity of the gold inert blocking electrode symmetric battery is tested by an alternating current impedance method by using the prepared gold inert blocking electrode symmetric battery, and the test and calculation result show that the ionic conductivity of the composite garnet type solid electrolyte reaches 6.31 multiplied by 10 at 30 DEG C -4 S/cm。
(5) The ionic conductivity and the electronic conductivity of the composite garnet-type solid electrolyte are tested and indirectly compared by a direct current method for the gold inert blocking electrode symmetrical battery and the lithium reversible electrode symmetrical battery respectively, and the result shows that the stable current of the gold inert blocking electrode symmetrical battery is 4 orders of magnitude lower than that of the lithium reversible electrode symmetrical battery, which indicates that the electronic conductivity of the composite garnet-type solid electrolyte is far lower than the ionic conductivity.
(6) Preparation of solid lithium ion battery
The composite garnet type solid electrolyte, lithium iron phosphate (anode) and metallic lithium (cathode) are assembled into a solid lithium ion battery, and the battery is subjected to cycle performance test, and the test result shows that the capacity retention rate of the battery is 83% after 100 charge-discharge cycles.
Comparative example 1
Comparative example 1 comprises the following steps:
(1) Preparation of garnet-type solid electrolyte (Li) by solid-phase method 7 La 3 Zr 1.2 V 0.4 Y 0.4 O 12 ) A substrate.
Taking LiOH and La which are raw materials required by preparing a matrix 2 O 3 、ZrO 2 、V 2 O 5 、Y 2 O 3 The mixing ratio of Li: la: zr: V: Y = 7. And putting the sieved mixed powder into a muffle furnace to be calcined for 9 hours at 1100 ℃ to form solid electrolyte matrix powder, feeding the solid electrolyte matrix powder into a ball milling tank to be ball milled for 10 hours at the rotating speed of 350rpm, and sieving by a sieve of 100 meshes again.
And (3) putting the sieved fine powder into a tabletting machine for tabletting treatment, and then, sending the powder into a muffle furnace for sintering for 2.5 hours at 1200 ℃ to obtain a garnet-type solid electrolyte matrix with the thickness of 80 microns. After cooling, the surface of the steel plate is finely ground to be flat.
(2) Preparation of symmetrical batteries
And sandwiching the garnet type solid electrolyte matrix between two lithium sheets, and performing cold pressing to combine the lithium reversible electrode symmetrical battery.
And sputtering a gold (Au) electrode on the garnet-type solid electrolyte matrix by a magnetron sputtering method to form the gold inert blocking electrode symmetrical battery.
(3) The conductivity of the gold inert blocking electrode symmetrical battery prepared by the method is tested by an alternating current impedance method, and the ionic conductivity of the garnet type solid electrolyte reaches 5.77 multiplied by 10 at the temperature of 30 ℃ as shown by test and calculation results -5 S/cm。
(4) The ionic conductivity and the electronic conductivity of the garnet type solid electrolyte are tested and indirectly compared by a direct current method for the gold inert blocking electrode symmetric battery and the lithium reversible electrode symmetric battery respectively, and the result shows that the stable current of the gold inert blocking electrode symmetric battery is 3 orders of magnitude lower than that of the lithium reversible electrode symmetric battery.
(5) Preparation of solid lithium ion battery
The garnet-type solid electrolyte, lithium iron phosphate (anode) and metallic lithium (cathode) are assembled into a solid lithium ion battery, the battery is subjected to cycle performance test, and the test result shows that the capacity retention rate of the battery is 56% after 100 charge-discharge cycles.
In the above embodiments, the descriptions of the respective embodiments have respective emphasis, and for parts that are not described in detail in a certain embodiment, reference may be made to related descriptions of other embodiments.
In the description herein, references to the description of the term "one embodiment," "some embodiments," "an example," "a specific example," or "some examples," etc., mean that a particular feature, structure, material, or characteristic described in connection with the embodiment or example is included in at least one embodiment or example of the invention. In this specification, the schematic representations of the terms used above should not be understood to necessarily refer to the same embodiment or example. Furthermore, the particular features, structures, materials, or characteristics described may be combined in any suitable manner in any one or more embodiments or examples. Furthermore, various embodiments or examples described in this specification can be combined and combined by one skilled in the art.
It will be apparent to those skilled in the art that various changes and modifications may be made in the present invention without departing from the spirit and scope of the invention. Thus, while the invention has been described with respect to the specific embodiments, it will be understood by those skilled in the art that various changes and modifications may be made therein without departing from the spirit and scope of the invention as defined in the appended claims.
While the invention has been described with reference to specific embodiments, the scope of the invention is not limited thereto, and various equivalent modifications and substitutions may be easily made by those skilled in the art within the technical scope of the present invention. Therefore, the protection scope of the present invention shall be subject to the protection scope of the claims.
Claims (10)
1. The composite garnet type solid electrolyte is characterized by comprising a substrate and a coating film coated on the surface of the substrate, wherein the substrate is the garnet type solid electrolyte, and the coating film comprises polyethylene glycol and polyethylene oxide.
2. The composite garnet-type solid electrolyte according to claim 1, wherein the coating film contains 10 to 20 mass% of polyethylene glycol.
3. The composite garnet-type solid electrolyte of claim 1, wherein the garnet-type solid electrolyte is Li a La 3 Zr b V c Y d O 12 Wherein a is 5 to 7; b is 1 to 2; c is 0 to 1; d is 0 to 1.
4. The composite garnet-type solid electrolyte as set forth in claim 1, wherein the coating film has a thickness of 10 to 20um.
5. The composite garnet-type solid electrolyte according to claim 1, wherein the thickness of the matrix is 40 to 100um.
6. The composite garnet-type solid electrolyte as set forth in claim 1, wherein the polyethylene glycol has a molecular weight of 400 to 20000.
7. The composite garnet-type solid electrolyte according to claim 1, wherein the polyethylene oxide has a molecular weight of 20000 to 10000000.
8. The method for producing a composite garnet-type solid electrolyte according to any one of claims 1 to 7, comprising:
s1, preparing a matrix by a solid-phase method, wherein the matrix is garnet-type solid electrolyte;
s2, preparing mixed slurry of polyethylene glycol and polyethylene oxide, and coating the mixed slurry on the surface of the matrix in a film forming manner by adopting a hot pressing method to form a coating.
9. The method according to claim 8, wherein the mass percentage of the polyethylene glycol in the coating film is 10-20%.
10. A secondary battery comprising the composite garnet-type solid electrolyte as set forth in any one of claims 1 to 7.
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| CN117059880A (en) * | 2023-07-18 | 2023-11-14 | 高能时代(珠海)新能源科技有限公司 | Sulfide solid electrolyte material and preparation method and application thereof |
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| Publication number | Priority date | Publication date | Assignee | Title |
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| CN117059880A (en) * | 2023-07-18 | 2023-11-14 | 高能时代(珠海)新能源科技有限公司 | Sulfide solid electrolyte material and preparation method and application thereof |
| CN117059880B (en) * | 2023-07-18 | 2024-04-12 | 高能时代(珠海)新能源科技有限公司 | Sulfide solid electrolyte material and preparation method and application thereof |
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