Inorganic solid electrolyte with soft characteristic, preparation method and solid-state battery

Abstract

The invention discloses an inorganic solid electrolyte with a soft characteristic, a preparation method and a solid-state battery, and belongs to the technical field of energy storage batteries. The chemical formula of the inorganic solid electrolyte is AaInObX < 3 + a-b >, A is selected from one of Li, Na, K and Ag, X is selected from one or more of F, Cl, Br and I, and 0.5 < = alt; 1, 0.5 lt; blt; and 1.5. Compared with traditional solid electrolytes such as Li3InBr6 and the like, the inorganic solid electrolyte provided by the invention has clay characteristics and high ionic conductivity due to O doping and A content regulation, and the problem of a positive electrode side interface of a solid battery can be solved. In addition, the halogen doped in the inorganic solid electrolyte further improves the ionic conductivity.

Description

Technical Field

[0001] The present invention relates to the technical field of energy storage batteries, and in particular to an inorganic solid electrolyte with soft properties, a preparation method, and a solid-state battery. Background Art

[0002] Lithium-ion batteries, with their high energy density and long service life, have developed rapidly and are widely used since their commercialization. However, with the advancement of scientific research, lithium-ion batteries using liquid electrolytes have reached their physical and chemical limits, making it difficult to meet the demand for new battery technologies with high energy density. Furthermore, the safety issues caused by highly flammable liquid electrolytes are also a cause for concern. All-solid-state batteries, which use flame-retardant inorganic solid materials as lithium-ion battery electrolytes, not only address the safety risks caused by organic electrolyte leakage and internal thermal runaway during the use of lithium-ion batteries, but also offer higher cycle life and energy density.

[0003] For the research and development of all-solid-state batteries, the key is to design and develop a series of solid electrolytes with high lithium ion conductivity, wide electrochemical window, good stability (including thermal stability, air stability, chemical and electrochemical stability), and excellent mechanical properties. The inorganic solid electrolytes that have been developed include oxides, sulfides and halides. However, most of these inorganic solid electrolytes need to be assembled and prepared under pressures of several hundred MPa to maintain close contact between the electrolyte and the electrode material. For example, Li3InBr6, which exists in powder form and has a room temperature ionic conductivity of 10 -4 S / cm. In the preparation of all-solid-state batteries, high pressure is required to ensure stable interfacial contact. Despite this, the solid electrolyte particles are still in rigid solid-solid contact with the cathode material particles, which hinders the conduction of lithium ions and increases the interfacial impedance.

[0004] Therefore, if the inorganic solid electrolyte also has soft properties similar to polymers, it can make the electrolyte and the positive electrode material in good contact under lower pressure, realizing low-pressure or pressure-free all-solid-state batteries, which is of great significance. Summary of the Invention

[0005] In view of the above-mentioned deficiencies in the prior art, the present invention provides an inorganic solid electrolyte with soft properties, a preparation method, and a solid-state battery, so as to solve the problem that the existing solid electrolyte cannot have both high ionic conductivity and good soft properties.

[0006] The technical solutions adopted by the present invention to solve the above technical problems are as follows:

[0007] In a first aspect of the present invention, there is provided an inorganic solid electrolyte having soft properties, wherein the chemical formula of the inorganic solid electrolyte is A a InOb X 3+a-b , wherein A is selected from one of Li, Na, K, and Ag, X is selected from one or more of F, Cl, Br, and I, 0.5≤a<1, 0.5 <b<1.5。

[0008] Optionally, A is Li, and X is Br or two of Br and F.

[0009] Optionally, the inorganic solid electrolyte is Li 0.65 InO 0.65 Br 2.04 F 0.31 、Li 0.66 InO 0.66 Br 2.08 F 0.24 、Li 0.50 InO 0.80 Br 1.9 、Li 0.60 InO 0.60 Br 2.4 One of them.

[0010] Optionally, the ionic conductivity of the inorganic solid electrolyte at room temperature is 10 -4 S / cm-10 -2 S / cm.

[0011] Optionally, the ionic conductivity of the inorganic solid electrolyte at room temperature is 10 -3 S / cm-10 -2 S / cm.

[0012] A second aspect of the present invention provides a method for preparing the inorganic solid electrolyte having soft properties according to the present invention, wherein the preparation method comprises the following steps:

[0013] According to the chemical formula of the inorganic solid electrolyte, the corresponding raw materials are mixed and ground to obtain a mixed powder;

[0014] The mixed powder is ball-milled to obtain an inorganic solid electrolyte with soft properties.

[0015] Optionally, the ball milling rotation speed is 400-600 rpm, the ball milling time is 18-72 h, the diameter of the zirconium beads is 5 mm, and the ball-to-material ratio is 20:1-40:1.

[0016] Optionally, when A is selected from Li, the raw materials are LiOH and InBr3, or the raw materials are at least one of InF3, InCl3, In2O3 and LiOH, InBr3.

[0017] According to a third aspect of the present invention, a solid-state battery is provided, comprising a positive electrode, a negative electrode, and a solid electrolyte located between the positive electrode and the negative electrode, wherein the solid electrolyte is the inorganic solid electrolyte with soft properties described in the present invention.

[0018] Optionally, the solid-state battery is a solid-state lithium battery.

[0019] Beneficial Effects: The present invention provides an inorganic solid electrolyte with soft properties, a preparation method, and a solid-state battery. The inorganic solid electrolyte provided by the present invention is an indium halide-based inorganic solid electrolyte. Compared with traditional solid electrolytes such as Li3InBr6, the inorganic solid electrolyte has clay properties and high ionic conductivity due to O doping and A (such as Li) content regulation, which can solve the interface problem on the positive electrode side of the solid-state battery. In addition, the halogen doped inorganic solid electrolyte of the present invention further improves the ionic conductivity. BRIEF DESCRIPTION OF THE DRAWINGS

[0020] Figure 1 is the XRD pattern (X-ray diffraction pattern) of the inorganic solid electrolyte prepared in Example 1 of the present invention;

[0021] Figure 2 EIS graph (electrochemical impedance spectroscopy) of the inorganic solid electrolyte prepared in Example 1 of the present invention;

[0022] Figure 3 This is a morphology diagram of the inorganic solid electrolyte prepared in Example 4 of the present invention;

[0023] Figure 4 This is a morphology diagram of the inorganic solid electrolyte prepared in Comparative Example 1 of the present invention. DETAILED DESCRIPTION

[0024] The present invention provides an inorganic solid electrolyte with flexible properties, a preparation method, and a solid-state battery. To clarify the objectives, technical solutions, and effects of the present invention, the present invention is described in further detail below. It should be understood that the specific embodiments described herein are intended only to illustrate the present invention and are not intended to limit the present invention.

[0025] The embodiment of the present invention provides an inorganic solid electrolyte with soft properties, the chemical formula of the inorganic solid electrolyte is A a InO b X 3+a-b , wherein A is selected from one of Li, Na, K, and Ag, X is selected from one or more of F, Cl, Br, and I, 0.5≤a<1, 0.5 <b<1.5。

[0026] The inorganic solid electrolyte provided by the embodiments of the present invention is an indium-based inorganic solid electrolyte of halogen oxide. Compared with traditional solid electrolytes such as Li3InBr6, the regulation of O doping and the content of A (such as Li) endows the inorganic solid electrolyte with clay characteristics and high ionic conductivity, which can solve the interface problem on the positive electrode side of solid-state batteries. In addition, the halogen doped in the inorganic solid electrolyte of the embodiments of the present invention further improves the ionic conductivity, and the highest ionic conductivity of the inorganic solid electrolyte of the embodiments of the present invention can reach 5.08×10 -3 S / cm.

[0027] It should be emphasized that the inorganic solid electrolyte provided by the embodiments of the present invention has good soft properties. It is like clay and eutectic-like at room temperature in a dry environment (H2O < 0.02 ppm), has viscoelasticity, and can deform freely under a relatively low pressure (<20 Mpa), so that it can be well adhered to the positive electrode material of the solid-state battery, solving the interface problem on the positive electrode side of the solid-state battery.

[0028] In some embodiments, the ionic conductivity of the inorganic solid electrolyte at room temperature (about 25°C) is 10 -4 S / cm - 10 -2 S / cm.

[0029] In some preferred embodiments, the ionic conductivity of the inorganic solid electrolyte at room temperature is 10 -3 S / cm - 10 -2 S / cm.

[0030] In some embodiments, 0.5 ≤ a < 0.7 and 0.5 < b < 1.0. Within this range, the inorganic solid electrolyte has both more excellent clay characteristics and ionic conductivity.

[0031] In some preferred embodiments, A is Li and X is Br. As an example, the inorganic solid electrolyte is Li 0.50 InO 0.80 Br 1.9 、Li 0.60 InO 0.60 Br 2.4 One of them. The above inorganic solid electrolytes all have soft and sticky properties and can achieve soft contact with the positive electrode under low pressure. And the above inorganic solid electrolytes have high ionic conductivity. In addition, the halogen atom Br has a higher lithium ion conductivity than F and Cl because the interaction between Br and Li is weaker, which is conducive to the migration of lithium ions.

[0032] In some more preferred embodiments, A is Li and X is two of Br and F. As an example, the inorganic solid electrolyte is Li 0.65 InO0.65 Br 2.04 F 0.31 、Li 0.66 InO 0.66 Br 2.08 F 0.24 The above inorganic solid electrolytes all have soft and sticky properties, which can achieve soft contact with the positive electrode under low pressure. The above inorganic solid electrolytes have high ionic conductivity. The introduction of F element doping further improves the ionic conductivity of the solid electrolyte. The ionic conductivity of the above inorganic solid electrolyte can be as high as 5.08×10 -3 S / cm.

[0033] An embodiment of the present invention provides a method for preparing the above-mentioned inorganic solid electrolyte with soft properties, the preparation method comprising the following steps:

[0034] According to the chemical formula of the inorganic solid electrolyte, the corresponding raw materials are mixed and ground to obtain a mixed powder;

[0035] The mixed powder is ball-milled to obtain an inorganic solid electrolyte with soft properties.

[0036] In some embodiments, the ball milling process is performed at a rotation speed of 400-600 rpm, for a time of 18-72 hours, with a zirconium bead diameter of 5 mm and a ball-to-material ratio of 20:1-40:1. Under these parameters, an inorganic solid electrolyte with both soft properties and high ionic conductivity can be obtained.

[0037] In some preferred embodiments, the ball milling process is performed at a rotation speed of 550 rpm, for a time of 32 hours, with a zirconium bead diameter of 5 mm and a ball-to-material ratio of 20:1. Under these parameters, an inorganic solid electrolyte with both soft properties and high ionic conductivity can be obtained while reducing preparation costs.

[0038] In some embodiments, when A is selected from Li, the raw materials are LiOH and InBr3, or the raw materials are at least one of InF3, InCl3, and In2O3, and LiOH and InBr3. The amount of LiOH may be 0.5-0.9 mol, the amount of InBr3 may be 1 mol, and the amount of InF3, InCl3, or In2O3 may be 0.1-0.2 mol.

[0039] In some embodiments, the preparation of the inorganic solid electrolyte is carried out under the protection of an inert atmosphere.

[0040] The entire preparation process is carried out under the protection of an inert atmosphere to prevent the reaction raw materials from reacting with air.

[0041] An embodiment of the present invention provides a solid-state battery, comprising a positive electrode, a negative electrode, and a solid electrolyte located between the positive electrode and the negative electrode, wherein the solid electrolyte is the inorganic solid electrolyte with soft properties described in the embodiment of the present invention.

[0042] The inorganic solid electrolyte of the embodiment of the present invention has good processing performance and high ionic conductivity, can be well bonded with the positive electrode of the solid-state battery, and effectively solves the interface problem on the positive electrode side of the solid-state battery.

[0043] In some embodiments, the solid-state battery is a solid-state lithium battery.

[0044] The present invention is further described in detail below through specific examples.

[0045] Example 1

[0046] An inorganic solid electrolyte (Li 0.65 InO 0.65 Br 2.04 F 0.31 ) is prepared, comprising the following steps:

[0047] LiOH, InBr3 and InF3 with a molar ratio of 0.75:1:0.15 were ground and mixed to obtain a mixed powder. The mixed powder was transferred to a ball mill and ball milled at a speed of 550 rpm, a ball milling time of 32 h, a zirconium bead diameter of 5 mm, and a ball-to-material ratio of 20:1. After the mixture was cooled to room temperature naturally, an inorganic solid electrolyte was obtained. The entire preparation process was carried out under the protection of an inert atmosphere to prevent the reaction raw materials from reacting with air. Its XRD pattern is shown as follows: Figure 1 The EIS diagram for calculating ionic conductivity is shown in Figure 2 shown.

[0048] Example 2

[0049] An inorganic solid electrolyte (Li 0.66 InO 0.66 Br 2.08 F 0.24 ), the preparation method of this embodiment is basically the same as that of Example 1, except that the reaction raw materials are LiOH, InBr3 and InF3 with a molar ratio of 0.75:1:0.125.

[0050] Example 3

[0051] An inorganic solid electrolyte (Li 0.50 InO 0.80 Br 1.9), the preparation method of this embodiment is basically the same as that of Example 1, except that the reaction raw materials are LiOH, InBr3 and In2O3 with a molar ratio of 0.625:1:0.125.

[0052] Example 4

[0053] An inorganic solid electrolyte (Li 0.60 InO 0.60 Br 2.4 ) is prepared. The preparation method of this embodiment is basically the same as that of Example 1, except that the reaction raw materials are LiOH and InBr3 with a molar ratio of 0.60:1. The morphology of the inorganic solid electrolyte prepared in this embodiment is shown in FIG. Figure 3 shown.

[0054] Comparative Example 1

[0055] Preparation of an inorganic solid electrolyte (Li3InBr6). The preparation method of this comparative example is basically the same as that of Example 1, except that the reaction raw materials are LiBr and InBr3 with a molar ratio of 3:1. The morphology of the inorganic solid electrolyte prepared in this comparative example is shown in FIG. Figure 4 shown.

[0056] Performance comparison test:

[0057] The inorganic solid electrolytes prepared in Examples 1-4 and Comparative Example 1 were tested for ionic conductivity in physical state and at room temperature (25°C). The test results are shown in Table 1. The ionic conductivity was measured by using a stainless steel sheet as a blocking electrode, weighing 180 mg of the inorganic solid electrolyte, placing it in a 10 mm mold, holding the pressure at 0.5 ton for 1 minute, and then rotating the filter at 1 Hz to 10 5 The resistance R is obtained by measuring the electrochemical impedance spectroscopy at a frequency of Hz, and its ionic conductivity is calculated according to the formula σ=L / SR, where σ is the ionic conductivity, L is the thickness of the powder after tableting, S is the surface area of ​​the powder after tableting, and R is the measured resistance.

[0058] Table 1

[0059] Chemical formula of inorganic solid electrolyte physical state Room temperature ionic conductivity (S / cm) Example 1 <![CDATA[Li 0.65 InO 0.65 Br 2.04 F 0.31 ]]> Soft clay-like, viscoelastic <![CDATA[5.08×10 -3 ]]> Example 2 <![CDATA[Li 0.66 InO 0.66 Br 2.08 F 0.24 ]]> Soft clay-like, viscoelastic <![CDATA[3.03×10 -3 ]]> Example 3 <![CDATA[Li 0.50 InO 0.80 Br 1.9 ]]> Clay-like, viscoelastic <![CDATA[2.37×10 -3 ]]> Example 4 <![CDATA[Li 0.60 InO 0.60 Br 2.4 ]]> Soft clay-like, viscoelastic <![CDATA[0.96×10 -3 ]]> Comparative Example 1 <![CDATA[Li3InBr6]]> Loose powder <![CDATA[0.120×10 -3 ]]>

[0060] From Table 1 above, it can be seen that the inorganic solid electrolyte provided by the embodiment of the present invention achieves the following effects:

[0061] Comparison of Examples 3 and 4 with Comparative Example 1 shows that the introduction of O doping and the reduction of Li content transform the solid electrolyte from a loose powder into a soft clay state, and the ionic conductivity is improved.

[0062] Comparing Examples 1, 2 with Examples 3, 4, it can be seen that the introduction of F element doping further improves the ionic conductivity of the solid electrolyte.

[0063] In summary, an inorganic solid electrolyte with soft characteristics, a preparation method thereof and a solid-state battery provided by the present invention, the chemical formula of the inorganic solid electrolyte is A a InO b X 3+a-b , where A is selected from one of Li, Na, K, Ag, X is selected from one or more of F, Cl, Br, I, 0.5 ≤ a < 1, 0.5 < b < 1.5. The ionic conductivity of the inorganic solid electrolyte of the present invention at room temperature is 10 -4 S / cm - 10 -2 S / cm, and the inorganic solid electrolyte has soft characteristics that most inorganic solid electrolytes do not have, and can solve the solid-solid contact problem on the positive electrode side of the solid-state battery.

[0064] It should be understood that the application of the present invention is not limited to the above examples. For those of ordinary skill in the art, improvements or transformations can be made according to the above description, and all such improvements and transformations should fall within the protection scope of the appended claims of the present invention.

Claims

1. An inorganic solid electrolyte with soft properties, characterized in that: The chemical formula of the inorganic solid electrolyte is A a InO b X 3+a-b , wherein A is selected from one of Li, Na, K, and Ag, X is selected from one or more of F, Cl, Br, and I, 0.5≤a<1, 0.5 <b<1.5。 2. The inorganic solid electrolyte with soft properties according to claim 1, characterized in that: A is Li, and X is Br or two of Br and F.

3. The inorganic solid electrolyte with soft properties according to claim 2, characterized in that: The inorganic solid electrolyte is Li 0.65 InO 0.65 Br 2.04 F 0.31 、Li 0.66 InO 0.66 Br 2.08 F 0.24 、Li 0.50 InO 0.80 Br 1.9 、Li 0.60 InO 0.60 Br 2.4 One of them.

4. The inorganic solid electrolyte with soft properties according to claim 1, characterized in that The ionic conductivity of the inorganic solid electrolyte at room temperature is 10 -4 S / cm-10 -2 S / cm.

5. The inorganic solid electrolyte with soft properties according to claim 4, characterized in that: The ionic conductivity of the inorganic solid electrolyte at room temperature is 10 -3 S / cm-10 -2 S / cm.

6. A method for preparing the inorganic solid electrolyte with soft properties according to any one of claims 1 to 5, characterized in that: The preparation method comprises the following steps: According to the chemical formula of the inorganic solid electrolyte, the corresponding raw materials are mixed and ground to obtain a mixed powder; The mixed powder is ball-milled to obtain an inorganic solid electrolyte with soft properties.

7. The method for preparing an inorganic solid electrolyte with soft properties according to claim 6, characterized in that: The ball milling process has a rotation speed of 400-600 rpm, a ball milling process time of 18-72 hours, a diameter of the zirconium beads of 5 mm, and a ball-to-material ratio of 20:1-40:

1.

8. The method for preparing an inorganic solid electrolyte with soft properties according to claim 6, characterized in that: When A is selected from Li, the raw materials are LiOH and InBr3, or the raw materials are at least one of InF3, InCl3, In2O3 and LiOH, InBr3.

9. A solid-state battery comprising a positive electrode, a negative electrode, and a solid electrolyte located between the positive electrode and the negative electrode, characterized in that: The solid electrolyte is the inorganic solid electrolyte with soft properties as described in any one of claims 1 to 5.

10. The solid-state battery according to claim 9, characterized in that The solid-state battery is a solid-state lithium battery.

Images