Composite solid electrolyte, preparation method thereof and all-solid-state battery
By introducing hydride into the oxide solid electrolyte to form a composite solid electrolyte, the problems of hard texture and low conductivity of the oxide solid electrolyte material are solved, and the circulation performance and safety of the battery are improved.
Patent Information
- Application Number
- CN202310757279.7
- Authority / Receiving Office
- CN · China
- Patent Type
- Applications(China)
- Current Assignee / Owner
- Filing Date
- 2023-06-26
- Publication Date
- 2024-12-27
AI Technical Summary
The oxide solid electrolyte has problems with hard material texture and low ionic conductivity, which leads to the inability to maintain good cycling efficiency in solid-state batteries and lithium metal solid-state batteries.
Using a composite solid electrolyte, including the combination of oxide Li1.3+x+yAl0.3-x-yMgxCayTi1.7(PO4)3 and hydrides LiNH2, Li2NH, Li3(NH2)2I, LiBH4, and LiAlH4, the dry planet is used. Ball mills are prepared by mixing to improve conductivity and reduce reaction temperature.
It improves conductivity, reduces shear modulus, forms dense sheets and improves lithium ion conduction networks, improving cycling and safety performance.
Smart Images
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Abstract
Description
Technical Field
[0001] The present invention relates to the field of electrochemical technology, and in particular to a composite solid electrolyte and a preparation method thereof, and an all-solid-state battery. Background Art
[0002] Compared with liquid batteries, solid-state batteries use solid electrolytes to replace the organic electrolytes of liquid battery systems, which can effectively avoid safety hazards caused by problems such as electrolyte leakage, thereby greatly improving the safety performance of batteries.
[0003] Solid-state battery systems can adapt to positive and negative electrode materials with higher energy density, which can effectively increase the energy density of battery cells and improve the low energy density problem of the current system.
[0004] Among the solid electrolyte systems currently under research, oxides are an important type of electrolyte material. Oxide solid electrolytes have the advantages of being stable to air and having low preparation cost. However, oxide solid electrolytes have the problems of hard material texture and low ionic conductivity. Summary of the invention
[0005] In order to overcome the problems of the oxide solid electrolyte in the prior art, such as hard material texture and low ion conductivity, and the inability to maintain good cycle efficiency in solid-state batteries and lithium metal solid-state batteries due to high Young's modulus and poor interface contact when using calcined oxide ceramic sheets, the present invention provides a composite solid electrolyte, including oxide and hydride.
[0006] The chemical formula of the oxide is: Li 1.3+x+y Al 0.3-x-y Mg x Ca y Ti 1.7 (PO4)3; and x and y satisfy the following conditions: 0 <x<0.05,0<y<0.05;
[0007] The hydride is selected from one or more of LiNH2, Li2NH, Li3(NH2)2I, LiBH4 and LiAlH4.
[0008] Preferably, x and y satisfy the following conditions: <x+y≤0.05。
[0009] Preferably, the particle size of the oxide is 50-600 nm, and within this particle size range, the oxide can be better compatible with the positive electrode material and the hydride material in terms of particle size.
[0010] Preferably, the material mass ratio of the hydride to the oxide is 1:4-4:1.
[0011] The present invention provides a method for preparing the composite solid electrolyte, wherein oxides and hydrides are mixed in proportion by dry planetary ball milling to obtain the solid electrolyte.
[0012] Preferably, the oxide and the hydride are placed in a planetary ball mill with a ball-to-material ratio of 20-40, a ball milling speed of 300-500 r / min, and a ball milling time of 2-4 h.
[0013] Preferably, Li2CO3 powder, NH4H2PO4 powder, TiO2 powder, Al2O3 powder, MgO powder and CaO powder are mixed and ball-milled according to the stoichiometric ratio of the LATP-MgCa structural formula, and calcined at a temperature of 600-800°C for 3-5h to obtain the oxide.
[0014] Preferably, Li2CO3 powder, NH4H2PO4 powder, TiO2 powder, Al2O3 powder, MgO powder and CaO powder are placed in a planetary ball mill according to the stoichiometric ratio of the LATP-MgCa structural formula, the rotation speed is controlled at 200-300 rpm, and the ball milling is performed for 6-10 hours. Then the obtained powder is loaded into an alumina crucible and then placed in a muffle furnace for calcination to obtain the oxide.
[0015] The present invention also provides an all-solid-state battery, comprising a positive electrode layer, a negative electrode layer and an electrolyte layer, wherein the electrolyte layer is the composite solid electrolyte described above.
[0016] Preferably, the positive electrode layer comprises a positive electrode active material and the composite solid electrolyte, and the mixing mass ratio of the positive electrode active material to the composite solid electrolyte is (2-9):1;
[0017] The electrolyte layer is a ceramic sheet formed by pressing the composite solid electrolyte;
[0018] The negative electrode layer is a lithium metal sheet.
[0019] Beneficial effects:
[0020] The beneficial effects produced by the technical solution of the present invention are as follows:
[0021] (1) By using oxide and hydride composite solid electrolytes, high-conductivity hydrides are ball-milled on the surface of nano-oxide solid electrolyte particles and the interface between particles, which effectively improves the low conductivity characteristics of the oxide green sheet and can effectively promote the application of non-sintered oxide-hydride composites in solid-state batteries.
[0022] (2) The oxide uses LATP-MgCa, which can further improve the conductivity, reduce the reaction temperature, and save the synthesis cost compared with LATP-Mg, thereby achieving the purpose of optimizing the synthesis method.
[0023] (3) The composite electrolyte can greatly improve the deformation ability of oxide-hydride composite electrolyte particles by taking advantage of the high lithium ion conductivity and low shear modulus of hydrides such as LiBH4, so that they can form dense sheets only after cold pressing, and then the contact between the two-phase particles is changed from "point contact" to "surface contact", thus forming a continuous lithium ion conduction network, ensuring the effective conduction of lithium ions between the positive and negative electrodes, and thus improving the cycle performance. DETAILED DESCRIPTION
[0024] In order to make the purpose, technical scheme and advantages of the embodiments of the present invention clearer, the technical scheme in the embodiments of the present invention will be clearly and completely described below. Obviously, the described embodiments are part of the embodiments of the present invention, rather than all the embodiments. Therefore, the following detailed description of the embodiments of the present invention is not intended to limit the scope of the claimed invention, but merely represents the selected embodiments of the present invention. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of the present invention.
[0025] This embodiment provides a composite solid electrolyte, including an oxide and a hydride.
[0026] The chemical formula of the oxide is: Li 1.3+x+y Al 0.3-x-y Mg x Ca y Ti 1.7 (PO4)3; and x and y satisfy the following conditions: 0 <x<0.05,0<y<0.05;
[0027] The hydride is selected from one or more of LiNH2, Li2NH, Li3(NH2)2I, LiBH4 and LiAlH4.
[0028] As a preferred implementation, x and y satisfy the following conditions: <x+y≤0.05。
[0029] As a preferred embodiment, the particle size of the oxide is 50-600 nm. The oxide particle size within this range can be better compatible with the positive electrode material and the hydride material in terms of particle size.
[0030] As a preferred embodiment, the material mass ratio of the hydride to the oxide is 1:4-4:1. Within this mass ratio range, the masses of the oxide particles and the hydride when compounded have good adaptability.
[0031] This embodiment provides a method for preparing the composite solid electrolyte, wherein oxide and hydride are mixed in proportion by dry planetary ball milling to obtain the solid electrolyte.
[0032] As a preferred embodiment, the oxide and the hydride are placed in a planetary ball mill with a ball-to-material ratio of 20-40, a ball milling speed of 300-500 r / min, and a ball milling time of 2-4 h.
[0033] As a preferred embodiment, Li2CO3 powder, NH4H2PO4 powder, TiO2 powder, Al2O3 powder, MgO powder and CaO powder are mixed and ball-milled in a stoichiometric ratio according to the LATP-MgCa structural formula, and calcined at a temperature of 850-900°C for 3-5h to obtain the oxide.
[0034] As a preferred embodiment, Li2CO3 powder, NH4H2PO4 powder, TiO2 powder, Al2O3 powder, MgO powder and CaO powder are placed in a planetary ball mill in proportion, the rotation speed is controlled at 200-300rpm, and the ball mill is performed for 6-10 hours. Then the obtained powder is loaded into an alumina crucible, and then placed in a muffle furnace for calcination to obtain the oxide.
[0035] This embodiment also provides an all-solid-state battery, including a positive electrode layer, a negative electrode layer and an electrolyte layer, wherein the electrolyte layer is the composite solid electrolyte mentioned above.
[0036] As a preferred embodiment, the positive electrode layer comprises a positive electrode active material and the composite solid electrolyte, and the mixing mass ratio of the positive electrode active material to the composite solid electrolyte is (2-9):1;
[0037] The electrolyte layer is a ceramic sheet formed by pressing the composite solid electrolyte;
[0038] The negative electrode layer is a lithium metal sheet.
[0039] The beneficial effects of the composite solid electrolyte in this embodiment are further reviewed below through several groups of examples and comparative examples.
[0040] (1) Preparation of LATP-MgCa
[0041] Li2CO3 powder, NH4H2PO4 powder, TiO2 powder, Al2O3 powder and MgO, CaO powder are ball-milled in a planetary ball mill at a speed of 250 rpm for 8 hours according to a certain stoichiometric ratio according to the structural formula of LATP-MgCa, and then the ball-milled powder is loaded into an alumina crucible, and then placed in a muffle furnace at 700°C for calcination for 5 hours to obtain LATP-MgCa, wherein the chemical formula of LATP-MgCa is: Li1.3+x+y Al 0.3-x-y Mg x Ca y Ti 1.7 (PO4)3; and 0 < x < 0.05, 0 < y < 0.05, 0 < x + y ≤ 0.05. After being refined by a refining device, the particle size of the obtained powder is between 50 - 600 nm.
[0042] (2) Preparation of composite solid electrolyte
[0043] In an argon glove box, take hydride and LATP - MgCa in proportion and place them in a ball - milling jar. The ball - to - powder ratio is 30, the ball - milling speed is 400 r / min, and after 3 h of ball - milling, a composite solid electrolyte is obtained.
[0044] (3) Preparation of all - solid - state battery
[0045] The positive electrode includes a positive electrode material layer formed by mixing the positive electrode active material LiCoO2 and the composite solid electrolyte powder in a mass ratio of 7:3.
[0046] The negative electrode is a lithium metal sheet.
[0047] The electrolyte layer is a ceramic sheet prepared from cold - pressed solid electrolyte powder.
[0048] According to the above - mentioned preparation process, Examples 1 - 22 and Comparative Examples 1 - 8 are designed. The differences among the examples and comparative examples lie in the components and particle size of the composite solid electrolyte, and other processes are the same. The specific details are shown in Table 1.
[0049] Table 1 Components and particle size of the composite solid electrolyte in examples and comparative examples
[0050]
[0051]
[0052]
[0053] Performance test
[0054] (1) Ion conductivity test
[0055] The alternating current impedance method is used to test the ion conductivity of the composite solid electrolytes obtained in Examples 1 - 22 and Comparative Examples 1 - 8. The instruments used are a solartron impedance meter, a sputtering coater, and a tablet press. The specific process is as follows: After taking out the tablets pressed by an electric tablet press under a pressure of 300 Mpa, sputter gold on the upper and lower surfaces in an Ar - filled glove box. The test range is 10 MHz - 0.1 Hz, and the perturbation voltage is 10 mV.
[0056] (2) Cycle efficiency test
[0057] The all-solid-state batteries obtained in Examples 1-22 and Comparative Examples 1-8 were subjected to a cycle efficiency test. At 60°C, the assembled all-solid-state batteries were charged to 4.2 V at a current density of 130 mA / g, and then discharged to 3.0 V. This cycle was repeated until the capacity retention rate was cycled to below 85%, and the number of cycles at which the capacity retention rate was above 85% was recorded.
[0058] The test results are as follows:
[0059] Table 2 Ionic conductivity and cycle efficiency test results in the examples and comparative examples
[0060]
[0061]
[0062] The above description is only a preferred embodiment of the present invention and is not intended to limit the present invention. For those skilled in the art, the present invention may have various modifications and variations. Any modification, equivalent replacement, improvement, etc. made within the spirit and principle of the present invention shall be included in the protection scope of the present invention.
Claims
1. A composite solid electrolyte, characterized in that: Including oxides and hydrides, The chemical formula of the oxide is: Li 1.3+x+y Al 0.3-x-y Mg x Ca y Ti 1.7 (PO4)3; and x and y satisfy the following conditions: 0 <x<0.05,0<y<0.05; The hydride is selected from one or more of LiNH2, Li2NH, Li3(NH2)2I, LiBH4 and LiAlH4.
2. A composite solid electrolyte according to claim 1, characterized in that: Where x and y satisfy the following conditions: 0 <x+y≤0.05。 3. A composite solid electrolyte according to claim 1, characterized in that: The particle size of the oxide is 50-600 nm.
4. A composite solid electrolyte according to claim 1, characterized in that: The material mass ratio of the hydride to the oxide is 1:4-4:
1.
5. A method for preparing a composite solid electrolyte according to any one of claims 1 to 4, characterized in that: The oxide and the hydride are mixed in proportion by dry planetary ball milling to obtain the solid electrolyte.
6. The method for preparing a composite solid electrolyte according to claim 5, characterized in that: Put the oxide and hydride into a planetary ball mill with a ball-to-material ratio of 20-40, a ball milling speed of 300-500 r / min, and a ball milling time of 2-4 h.
7. The method for preparing a composite solid electrolyte according to claim 5, characterized in that: Li2CO3 powder, NH4H2PO4 powder, TiO2 powder, Al2O3 powder, MgO powder and CaO powder are mixed and ball-milled in proportion, and calcined at a temperature of 600-800°C for 3-5h to obtain the oxide.
8. The method for preparing a composite solid electrolyte according to claim 7, characterized in that: Li2CO3 powder, NH4H2PO4 powder, TiO2 powder, Al2O3 powder, MgO powder and CaO powder are put into a planetary ball mill in proportion, the rotation speed is controlled at 200-300rpm, and the ball mill is performed for 6-10 hours. Then the obtained powder is loaded into an alumina crucible, and then placed in a muffle furnace for calcination to obtain the oxide.
9. An all-solid-state battery, characterized in that: The invention comprises a positive electrode layer, a negative electrode layer and an electrolyte layer, wherein the electrolyte layer adopts the composite solid electrolyte as claimed in any one of claims 1 to 4.
10. The all-solid-state battery according to claim 9, characterized in that: The positive electrode layer includes a positive electrode active material and the composite solid electrolyte, and the mixing mass ratio of the positive electrode active material to the composite solid electrolyte is (2-9):1; The electrolyte layer is a ceramic sheet formed by pressing the composite solid electrolyte; The negative electrode layer is a lithium metal sheet.