Patent Application
20230006246
The present disclosure relates to a method for producing a halide.
International Publication No. WO2018/025582 discloses a method for producing a halide solid electrolyte.
One non-limiting and exemplary embodiment provides a halide production method with high industrial productivity.
In one general aspect, the techniques disclosed here feature a method for producing a halide, the method including heat-treating a material mixture containing LiA, YB3, GdC3, and CaD2 in an inert gas atmosphere. A, B, C, and D are each independently at least one selected from the group consisting of F, Cl, Br, and I. In the heat-treating, the material mixture is heat-treated at higher than or equal to 200° C. and lower than or equal to 700° C.
The present disclosure provides a halide production method with high industrial productivity.
Additional benefits and advantages of the disclosed embodiment will become apparent from the specification and drawings. The benefits and/or advantages may be individually obtained by the embodiment and features of the specification and drawings, which need not all be provided in order to obtain one or more of such benefits and/or advantages.
An embodiment will next be described with reference to the drawings.
The production method in the first embodiment includes a heat treatment step S1000. In the heat treatment step S1000, a material mixture is heat-treated in an inert gas atmosphere.
The material mixture heat-treated in the heat treatment step S1000 contains LiA, YB3, GdC3, and CaD2. A, B, C, and D are each independently at least one selected from the group consisting of F, Cl, Br, and I.
In the heat treatment step S1000, the material mixture is heat-treated at higher than or equal to 200° C. and lower than or equal to 700° C. Here, the heat treatment temperature is an ambient temperature.
The production method in the first embodiment is a halide production method with high industrial productivity. The method with high industrial productivity is, for example, a method capable of mass production at low cost. Specifically, this production method allows a halide containing Li (i.e., lithium), Y (i.e., yttrium), Gd (i.e., gadolinium), and Ca (i.e., calcium) to be produced in a simple manner (i.e., by sintering in an inert gas atmosphere).
In the production method in the first embodiment, a vacuum sealed tube and a planetary ball mill may not be used.
In the heat treatment step S1000, for example, a powder of the material mixture may be placed in a container (e.g., a crucible) and heat-treated in a heating furnace. In this case, the material mixture heated to “higher than or equal to 200° C. and lower than or equal to 700° C.” in the inert gas atmosphere may be held for a prescribed time period or more.
The heat treatment time period may be the length of time that does not cause a change in the composition of the heat-treated product due to volatilization of the halide etc. The length of time that does not cause a change in the composition of the heat-treated product means a heat treatment time period that does not cause deterioration of the ionic conductivity of the heat-treated product. With the production method in the first embodiment, a halide having, for example, an ionic conductivity higher than or equal to 1.2×10−6 S/cm at around room temperature can be produced.
To produce a halide having higher ionic conductivity using the highly industrially productive method, the material mixture may be heat-treated in the heat treatment step S1000 at higher than or equal to 300° C. and lower than or equal to 700° C. When the heat treatment temperature is higher than or equal to 300° C., the reaction of the material mixture can proceed sufficiently. Specifically, LiA, YB3, GdC3, and CaD2 can be allowed to react sufficiently.
To produce a halide having higher ionic conductivity using the highly industrially productive method, the material mixture may be heat-treated in the heat treatment step S1000 at higher than or equal to 350° C. For example, the material mixture may be heat-treated at higher than or equal to 350° C. and lower than or equal to 700° C. When the heat treatment temperature is higher than or equal to 350° C., the halide, which is the heat-treated product, has higher crystallinity. Therefore, the ionic conductivity of the halide that is the heat-treated product can be further increased. Specifically the halide solid electrolyte material obtained can have better quality.
To produce a halide having higher ionic conductivity using the highly industrially productive method, the material mixture may be heat-treated in the heat treatment step S1000 at higher than or equal to 400° C. For example, the material mixture may be heat-treated at higher than or equal to 400° C. and lower than or equal to 700° C. When the heat treatment temperature is higher than or equal to 400° C., the halide, which is the heat-treated product, has higher crystallinity. Therefore, the ionic conductivity of the halide that is the heat-treated product can be further increased. Specifically, the halide solid electrolyte material obtained can have better quality.
To produce a halide having higher ionic conductivity using the highly industrially productive method, the material mixture may be heated in the heat treatment step S1000 at lower than or equal to 650° C. For example, the material mixture may be heat-treated at higher than or equal to 300° C. and lower than or equal to 650° C., at higher than or equal to 350° C. and lower than or equal to 650° C., or at higher than or equal to 400° C. and lower than or equal to 650° C. When the heat treatment temperature is lower than or equal to 650° C., the halide formed by the solid phase reaction can be prevented from undergoing thermal decomposition. In this case, the ionic conductivity of the halide, which is the heat-treated product, can be increased. Specifically, the halide solid electrolyte material obtained has high quality.
To produce a halide having higher ionic conductivity using the highly industrially productive method, the material mixture may be heat-treated in the heat treatment step S1000 at lower than or equal to 550° C. For example, the material mixture may be heat-treated at higher than or equal to 300° C. and lower than or equal to 550° C., at higher than or equal to 350° C. and lower than or equal to 550° C., or at higher than or equal to 400° C. and lower than or equal to 550° C. Specifically, the temperature lower than or equal to 550° C. is a temperature lower than or equal to the melting point of LiBr. Therefore, when the heat treatment temperature is lower than or equal to 550° C., the decomposition of LiBr can be prevented. In this case, the ionic conductivity of the halide, which is the heat-treated product, can be further increased. Specifically, the halide solid electrolyte material obtained can have better quality.
To produce a halide having higher ionic conductivity using the highly industrially productive method, the material mixture may be heat-treated in the heat treatment step S1000 in more than or equal to 0.5 hours and less than or equal to 60 hours. When the heat treatment time period is more than or equal to 0.5 hours, the reaction of the material mixture can proceed sufficiently. Specifically, LiA, YB3, GdC3, and CaD2 can be allowed to react sufficiently. When the heat treatment time period is less than or equal to 60 hours, the halide, which is the heat-treated product, can be prevented from volatilizing. Therefore, the halide obtained has the target composition. Specifically, a reduction in the ionic conductivity of the halide due to a change in the composition can be prevented. In other words, the halide solid electrolyte material obtained can have better quality.
To produce a halide having higher ionic conductivity using the highly industrially productive method, the material mixture may be heat-treated in the heat treatment step S1000 in less than or equal to 24 hours. For example, the material mixture may be heat-treated in more than or equal to 0.5 hours and less than or equal to 24 hours. When the heat treatment time period is less than or equal to 24 hours, the volatilization of the halide, which is the heat-treated product, can be further prevented. Therefore, the halide obtained has the target composition. Specifically, a reduction in the ionic conductivity of the halide due to a change in the composition can be prevented. In other words, the halide solid electrolyte material obtained can have better quality.
The inert gas atmosphere means, for example, an atmosphere in which the total concentration of gases other than the inert gas is lower than or equal to 1% by volume. Examples of the inert gas include helium, nitrogen, and argon.
After the heat treatment step S1000, the heat-treated product may be pulverized. In this case, a pulverizing apparatus (such as a mortar or a mixer) may be used.
The material mixture may be a material prepared by mixing LiA, YB3, GdC3, and CaD2. Alternatively, the material mixture may be a material containing LiA, YB3, GdC3, and CaD2 and further containing mixed therein a material other than LiA, YB3, GdC3, and CaD2.
To improve the characteristics of the halide, the material mixture may be a material further containing MαXβ mixed therein. For example, to increase the ionic conductivity, the material mixture may be a material further containing MαXβ mixed therein.
Here, M includes at least one selected from the group consisting of Na, K, Mg, Sr, Ba, Zn, In, Sn, Bi, La, Ce, Pr, Nd, Pm, Sm, Eu, Tb, Dy, Ho, Er, Tm, Yb, and Lu. X is at least one selected from the group consisting of F, Cl, Br, and I. α>0 and β>0 are satisfied.
To improve the characteristics of the halide, α=1 and 2≤β≤5 may be satisfied.
Part of metal cations in at least one selected from the group consisting of LiA, YB3, GdC3, and CaD2 contained in the material mixture may be replaced with other metal cations. Specifically, part of Li, Y, Gd, and Ca may be replaced with M described above. In other words, the material mixture may further contain a compound containing LiA with part of Li replaced with other metal cations, a compound containing YB3 with part of Y replaced with other metal cations, a compound containing GdC3 with part of Gd replaced with other metal cations, or a compound containing CaD2 with part of Ca replaced with other metal cations.
To further increase the ionic conductivity of the halide, A, B, C, and D may be each independently at least one selected from the group consisting of Cl and Br.
Specifically, the material mixture may be a material obtained by mixing “LiCl (i.e., lithium chloride) or LiBr (i.e., lithium bromide),” “YCl3 (i.e., yttrium chloride) or YBr3 (yttrium bromide),” “GdCl3 (i.e., gadolinium chloride) or GdBr3 (i.e., gadolinium bromide),” and “CaCl2 (i.e., calcium chloride) or CaBr2 (i.e., calcium bromide).”
As shown in
In the mixing step S1100, LiA, YB3, GdC3, and CaD2 used as raw materials are mixed. A material mixture is thereby obtained. Specifically, the material to be heat-treated in the heat treatment step S1000 is obtained.
To mix the raw materials, a well-known mixer (such as a mortar, a blender, or a ball mill) may be used.
For example, in the mixing step S1100, powders of the raw materials may be prepared and mixed. In this case, in the heat treatment step S1000, the material mixture in a powder form may be heat-treated. The powdery material mixture obtained in the mixing step S1100 may be formed into pellets. In the heat treatment step S1000, the material mixture in the form of pellets may be heat-treated.
In the mixing step S1100, not only LiA, YB3, GdC3, and CaD2 but also a raw material other than LiA, YB3, GdC3, and CaD2 (for example, MαXβ described above) may be mixed to obtain a material mixture.
In the mixing step S1100, “a raw material containing LiA as a main component,” “a raw material containing YB3 as a main component,” “a raw material containing GdC3 as a main component,” and “a raw material containing CaD2 as a main component” may be mixed to obtain a material mixture. The main component is a component whose molar ratio is highest.
In the mixing step S1100, LiA, YB3, GdC3, and CaD2 may be prepared such that the target composition is satisfied and then mixed.
For example, LiCl, LiBr, YCl3, GdCl3, and CaBr2 may be mixed such that the molar ratio LiCl:LiBr:YCl3:GdCl3:CaBr2=1:1.8:0.5:0.5:0.1. In this case, a halide having a composition represented by Li2.8Y8.5Gd0.5Br2Cl4 is obtained.
The molar ratio of LiA, YB3, GdC3, and CaD2 may be adjusted in advance so as to compensate for the change in the composition that may occur in the heat treatment step S1000.
In the mixing step S1100, not only LiA, YB3, GdC3, and CaD2 but also MαClβ or MαBrβ may be mixed to obtain a material mixture. Specifically, a compound represented by MαXβ in the first embodiment with X being Cl or Br may be further mixed to obtain the material mixture.
As shown in
In the preparation step S1200, raw materials such as LiA, YB3, GdC3, and CaD2 are prepared. Specifically, the materials to be mixed in the mixing step S1100 are prepared.
In the preparation step S1200, raw materials such as LiA, YB3, GdC3, and CaD2 may be synthesized. Alternatively, in the preparation step S1200, well-known commercial products (e.g., materials with a purity higher than or equal to 99%) may be used.
The materials prepared may be dried.
Examples of the form of each of the materials prepared include a crystalline form, a lump form, a flake form, and a powder form. In the preparation step S1200, crystalline, lump-like, or flake-like raw materials may be pulverized to obtain powdery raw materials.
To improve the characteristics (e.g., conductivity) of the halide, MαXβ may be added in the preparation step S1200. Here, M is at least one selected from the group consisting of Na, K, Mg, Sr, Ba, Zn, In, Sn, Bi, La, Ce, Pr, Nd, Pm, Sm, Eu, Tb, Dy, Ho, Er, Tm, Yb, and Lu. X is at least one selected from the group consisting of Cl and Br. α=1 and 2≤β≤5 are satisfied.
In the preparation step S1200, part of metal cations in at least one selected from the group consisting of LiA, YB3, GdC3, and CaD2 (i.e., part of at least one selected from the group consisting of Li, Y, Gd, and Ca) may be replaced with other metal cations (e.g., M described above). Specifically, a compound containing LiA with part of Li replaced with other metal cations, a compound containing YB3 with part of Y replaced with other metal cations, a compound containing GdC3 with part of Gd replaced with other metal cations, or a compound containing CaD2 with part of Ca replaced with other metal cations may be further prepared.
The halide produced by the production method of the present disclosure can be used as a solid electrolyte material. This solid electrolyte material is, for example, a solid electrolyte material having lithium ion conductivity. This solid electrolyte material is used, for example, for an all-solid-state lithium ion secondary battery.
The present disclosure will next be described in more detail with reference to Examples.
In the following Examples, halides produced by the production method of the present disclosure were evaluated as solid electrolyte materials.
In an argon atmosphere with a dew point lower than or equal to −60° C. and an oxygen concentration lower than or equal to 0.0001% by volume (this atmosphere is hereinafter referred to as a “dry argon atmosphere”), powders of LiCl, LiBr, YCl3, GdCl3, and CaBr2 were prepared as raw material powders such that the molar ratio LiCl:LiBr:YCl3:GdCl3:CaBr2 was 1:1.8:0.5:0.5:0.1. These materials were pulverized in an agate mortar and mixed. The mixture obtained was placed in an alumina crucible and heat-treated in the dry argon atmosphere at 500° C. for 0.5 hours. The heat-treated product obtained was pulverized in an agate mortar. A solid electrolyte material in Example 1 was thereby obtained.
The press forming die 200 includes an upper punch 201, a frame die 202, and a lower punch 203. The frame die 202 is formed of insulating polycarbonate. The upper punch 201 and the lower punch 203 are formed of electron conductive stainless steel.
The press forming die 200 shown in
The solid electrolyte material powder in Example 1 was filled into the press forming die 200 in the dry argon atmosphere. The upper punch 201 and the lower punch 203 were used to apply a pressure of 300 MPa to the solid electrolyte material in Example 1 disposed inside the press forming die 200.
With the pressure applied, the upper punch 201 and the lower punch 203 were connected to a potentiostat (VersaSTAT 4, Princeton Applied Research) equipped with a frequency response analyzer. The upper punch 201 was connected to a working electrode and a potential measurement terminal. The lower punch 203 was connected to a counter electrode and a reference electrode. The impedance of the solid electrolyte material was measured at room temperature using an electrochemical impedance measurement method.
In
σ=(RSE×S/t)−1 (1)
Here, σ represents the ionic conductivity. S represents the area of contact between the solid electrolyte material and the upper punch 201 (that is equal to the cross-sectional area of a hollow portion of the frame die 202 in
The ionic conductivity of the solid electrolyte material in Example 1 was 3.8×10−3 S/cm as measured at 25° C.
In Examples 2 to 21, LiCl, LiBr, YCl3, GdCl3, and CaBr2 were prepared in the dry argon atmosphere such that the molar ratio LiCl:LiBr:YCl3:GdCl3:CaBr2 was 1:1.8:0.5:0.5:0.1.
In Examples 22 and 23, LiCl, YBr3, GdCl3, and CaBr2 were prepared in the dry argon atmosphere such that the molar ratio LiCl:YBr3:GdCl3:CaBr2 was 2.2:0.6:0.6:0.1.
In Examples 24 and 25, LiCl, LiBr, YCl3, GdCl3, and CaBr2 were prepared in the dry argon atmosphere such that the molar ratio LiCl:LiBr:YCl3:GdCl3:CaBr2 was 1.6:1.8:0.4:0.4:0.1.
In Example 26, LiCl, LiBr, YCl3, GdCl3, and CaBr2 were prepared in the dry argon atmosphere such that the molar ratio LiCl:LiBr:YCl3:GdCl3:CaBr2 was 1:1.9:0.5:0.5:0.05.
In Example 27, LiCl, LiBr, YCl3, GdCl3, and CaBr2 were prepared in the dry argon atmosphere such that the molar ratio LiCl:LiBr:YCl3:GdCl3:CaBr2 was 1:1.85:0.5:0.5:0.075.
In Example 28, LiCl, LiBr, YCl3, GdCl3, and CaBr2 were prepared in the dry argon atmosphere such that the molar ratio LiCl:LiBr:YCl3:GdCl3:CaBr2 was 1:1.75:0.5:0.5:0.125.
In Example 29, LiCl, LiBr, YCl3, GdCl3, and CaBr2 were prepared in the dry argon atmosphere such that the molar ratio LiCl:LiBr:YCl3:GdCl3:CaBr2 was 1:1.7:0.5:0.5:0.15.
In Example 30, LiCl, LiBr, YCl3, GdCl3, and CaBr2 were prepared in the dry argon atmosphere such that the molar ratio LiCl:LiBr:YCl3:GdCl3:CaBr2 was 1:1.6:0.5:0.5:0.2.
In Example 31, LiCl, LiBr, YCl3, GdCl3, and CaBr2 were prepared in the dry argon atmosphere such that the molar ratio LiCl:LiBr:YCl3:GdCl3:CaBr2 was 1:1.85:0.3:0.7:0.075.
In Example 32, LiCl, LiBr, YCl3, GdCl3, and CaBr2 were prepared in the dry argon atmosphere such that the molar ratio LiCl:LiBr:YCl3:GdCl3:CaBr2 was 1:1.85:0.45:0.55:0.075.
In Example 33, LiCl, LiBr, YCl3, GdCl3, and CaBr2 were prepared in the dry argon atmosphere such that the molar ratio LiCl:LiBr:YCl3:GdCl3:CaBr2 was 1:1.85:0.5:0.5:0.075.
In Example 34, LiCl, LiBr, YCl3, GdCl3, and CaBr2 were prepared in the dry argon atmosphere such that the molar ratio LiCl:LiBr:YCl3:GdCl3:CaBr2 was 1:1.85:0.55:0.45:0.075.
In Example 35, LiCl, LiBr, YCl3, GdCl3, and CaBr2 were prepared in the dry argon atmosphere such that the molar ratio LiCl:LiBr:YCl3:GdCl3:CaBr2 was 1:1.85:0.7:0.3:0.075.
In Example 36, LiCl, LiBr, YCl3, GdCl3, and CaBr2 were prepared in the dry argon atmosphere such that the molar ratio LiCl:LiBr:YCl3:GdCl3:CaBr2 was 1:1.85:0.9:0.1:0.075.
In Example 37, LiCl, LiBr, YCl3, GdCl3, and CaBr2 were prepared in the dry argon atmosphere such that the molar ratio LiCl:LiBr:YCl3:GdCl3:CaBr2 was 0.5:2.3:0.5:0.5:0.1.
In Example 38, LiBr, YCl3, GdCl3, and CaBr2 were prepared in the dry argon atmosphere such that the molar ratio LiBr:YCl3:GdCl3:CaBr2 was 2.8:0.5:0.5:0.1.
In Example 39, LiCl, LiBr, YBr3, GdCl3, and CaBr2 were prepared in the dry argon atmosphere such that the molar ratio LiCl:LiBr:YBr3:GdCl3:CaBr2 was 1:1.8:0.5:0.5:0.1.
In Example 40, LiCl, LiBr, YBr3, GdBr3, and CaBr2 were prepared in the dry argon atmosphere such that the molar ratio LiCl:LiBr:YBr3:GdBr3:CaBr2 was 2:0.8:0.6:0.4:0.1.
In Example 41, LiCl, YBr3, GdBr3, and CaCl2 were prepared in the dry argon atmosphere such that the molar ratio LiCl:YBr3:GdBr3:CaCl2 was 2.6:0.6:0.4:0.1.
In Example 42, LiCl, LiBr, YCl3, GdCl3, and CaCl2 were prepared in the dry argon atmosphere such that the molar ratio LiCl:LiBr:YCl3:GdCl3:CaCl2 was 0.5:2.3:0.6:0.4:0.1.
In Example 43, LiCl, LiBr, YCl3, GdCl3, and CaCl2 were prepared in the dry argon atmosphere such that the molar ratio LiCl:LiBr:YCl3:GdCl3:CaCl2 was 1:1.8:0.6:0.4:0.1.
In Example 44, LiCl, LiBr, YCl3, GdCl3, and CaCl2 were prepared in the dry argon atmosphere such that the molar ratio LiCl:LiBr:YCl3:GdCl3:CaCl2 was 1.3:0.5:0.6:0.4:0.1.
In Example 45, LiCl, LiBr, YCl3, GdCl3, and CaCl2 were prepared in the dry argon atmosphere such that the molar ratio LiCl:LiBr:YCl3:GdCl3:CaCl2 was 1.8:1:0.6:0.4:0.1.
Raw material powders prepared in the dry argon atmosphere were pulverized in an agate mortar and mixed. The powder mixture obtained was placed in an alumina crucible and heat-treated in the dry argon atmosphere. The heat treatment temperature and the heat treatment time period are shown in Table 1 or 2. Each of the heat-treated products obtained was pulverized in an agate mortar. Solid electrolyte materials in Examples 2 to 45 were thereby obtained.
The ionic conductivity of each of the solid electrolyte materials in Examples 2 to 45 was measured in the same manner as in Example 1. The measurement results are shown in Tables 1 and 2.
As can be seen from Examples 1 to 45, when the heat treatment temperature is higher than or equal to 200° C. and lower than or equal to 700° C., the halide obtained has a high ionic conductivity higher than or equal to 1.2×106 S/cm at room temperature. This indicates that the solid electrolyte materials in Examples 1 to 45 have high crystallinity.
As can be seen by comparing Example 21 with Examples 2, 7 to 16, and 19, when the heat treatment temperature is higher than or equal to 300° C. and lower than or equal to 700° C., the ionic conductivity of the solid electrolyte material is higher. As can be seen by comparing Examples 7 and 16 with Examples 2 and 8 to 15, when the heat treatment temperature is higher than or equal to 400° C. and lower than or equal to 650° C., the ionic conductivity of the solid electrolyte material is still higher. As can be seen by comparing Examples 8 and 15 with Examples 2 and 9 to 14, when the heat treatment temperature is higher than or equal to 420° C. and lower than and equal to 600° C., the ionic conductivity of the solid electrolyte material is still higher. When the heat treatment is performed at any of the above heat treatment temperatures, the solid electrolyte material can have high crystallinity, and a change in composition due to thermal decomposition at high temperature may be prevented.
As can be seen by comparing Examples 1 to 3 with Examples 4 to 6, when the heat treatment time period is more than or equal to 0.5 hours and less than or equal to 3 hours, the ionic conductivity of the solid electrolyte material is higher.
As described above, the solid electrolyte materials produced by the production method of the present disclosure have high lithium ion conductivity. Moreover, the production method of the present disclosure is a simple method and is a method with high industrial productivity.
The production method of the present disclosure is used, for example, as a method for producing a solid electrolyte material. The solid electrolyte material produced by the production method of the present disclosure is used, for example, for an all-solid-state lithium ion secondary battery.
| Number | Date | Country | Kind |
|---|---|---|---|
| 2020-064755 | Mar 2020 | JP | national |
| Number | Date | Country | |
|---|---|---|---|
| Parent | PCT/JP2021/002509 | Jan 2021 | US |
| Child | 17929327 | US |
