Oxide for solid electrolyte and method for producing same, and solid electrolyte and method for producing same

Abstract

The present disclosure provides an oxide which is for a solid electrolyte, and the composition of which can be represented by formula I.　Formula I: xLi3BO3·yLi2SO4·zG, where G is at least one selected from the group consisting of B2O3, SiO2, Al2O3, P2O5, GeO2, V2O5, TeO2, Li3PO4, Li4B2O5 and Li2B4O7, and x, y, and z are numerical values satisfying 30 ≤ x ≤ 98, 1 ≤ y ≤ 40, 0.5 ≤ z ≤ 60, x / y ≥ 2, and x + y + z = 100.

Description

Oxide for solid electrolyte and method for producing the same, and solid electrolyte and method for producing the same

[0001] The present invention relates to an oxide for a solid electrolyte and a method for producing the same, and also to a solid electrolyte and a method for producing the same.

[0002] Li3BO3-Li2SO4-based materials are known as oxide-based solid electrolytes with lithium ion conductivity. Li3BO3-Li2SO4-based materials have the advantage of being able to be densified by press molding at room temperature.

[0003] Patent Document 1 discloses a Li3BO3-Li2SO4-based solid electrolyte. In the manufacturing method disclosed in Patent Document 1, first, Li3BO3 crystals and Li2SO4 crystals are subjected to a mechanical milling process. The mechanical milling process is performed using, for example, a planetary ball mill. Through this process, the raw materials are very finely pulverized and mixed, and are vitrified in this process. Next, a heat treatment is performed, and the vitrified oxide is transformed into a glass ceramic, and its ionic conductivity is increased. Mechanical milling makes it possible to vitrify raw materials having compositions that cannot be vitrified by melting methods.

[0004] Japanese Patent Application Laid-Open No. 2015-176854

[0005] Mechanical milling requires a long time. For example, in the examples of Patent Document 1, the treatment is carried out in an argon atmosphere for 40 to 70 hours.

[0006] At least one aspect of the present invention aims to improve the mass productivity of Li3BO3-Li2SO4-based oxides for solid electrolytes, and at least one aspect of the present invention aims to provide a novel Li3BO3-Li2SO4-based oxide for solid electrolytes.

[0007] In one aspect, the present invention provides an oxide for a solid electrolyte, the composition of which can be expressed by formula I: Formula I: xLi3BO3.yLi2SO4.zG, wherein G is at least one selected from the group consisting of B2O3, SiO2, Al2O3, PO5, GeO2, VO5, TeO2, Li3PO4, Li4B2O5, and Li2B4O7, and x, y, and z are numbers that satisfy 30≦x≦98, 1≦y≦40, 0.5≦z≦60, x / y≧2, and x+y+z=100.

[0008] In one aspect, the present invention provides a method for producing an oxide for a solid electrolyte, the method comprising: heating a raw material prepared so that the composition can be expressed by the above formula I to form a melt; and cooling the melt to obtain a solidified melt.

[0009] In one aspect, the present invention provides a solid electrolyte comprising the oxide for a solid electrolyte according to the present invention.

[0010] In one aspect, the present invention provides a method for producing a solid electrolyte, which comprises heat-treating the oxide for a solid electrolyte according to the present invention.

[0011] In one aspect, the present invention provides a method for producing a solid electrolyte, comprising: carrying out the method for producing an oxide for a solid electrolyte according to the present invention; and heat-treating the melt solidified body.

[0012] According to one aspect of the present invention, it is possible to produce a Li3BO3-Li2SO4-based oxide for a solid electrolyte by a so-called melting method. Also, according to one aspect of the present invention, a novel Li3BO3-Li2SO4-based oxide for a solid electrolyte is provided that can be obtained by an improved production method.

[0013] Hereinafter, embodiments of the present invention will be described, but the following description is not intended to limit the present invention to any particular embodiment.

[0014] In this specification, "melt-solidified body" means a solid obtained through the process of cooling and solidifying a melt. A melt-solidified body differs in its microstructure from a pressed body obtained by pressing raw materials such as powder. "Glass-like" means a solid whose glass transition point can be confirmed by differential scanning calorimetry. "Glass-ceramic-like" means a glass-like solid in which the presence of crystals can be observed.

[0015] [Oxide for Solid Electrolyte] First, as one embodiment of the present invention, an oxide for a solid electrolyte having a composition that can be represented by formula I will be described.

[0016] Formula I: xLi3BO3.yLi2SO4.zG Here, G is at least one selected from the group consisting of B2O3, SiO2, Al2O3, P2O5, GeO2, VO5, TeO2, Li3PO4, Li4B2O5 ​​and Li2B4O7, and x, y and z are numbers that satisfy 30≦x≦98, 1≦y≦40, 0.5≦z≦60, x / y≧2 and x+y+z=100.

[0017] The elements constituting G other than Li and O have the common feature of having glass network-forming ability. G may be at least one selected from the group consisting of B2O3, SiO2, Al2O3, PO5, GeO2, VO5, and TeO2. In this case, G may further contain Li3PO4. G may further contain at least two selected from the group consisting of B2O3, SiO2, Al2O3, PO5, GeO2, VO5, TeO2, Li3PO4, Li4B2O5, and Li2B4O7. G may contain at least one selected from the group consisting of B2O3, SiO2, and PO5. G may contain at least one selected from the group consisting of B2O3, SiO2, and Li3PO4.

[0018] The lower limit of x may be 50 or more, 60 or more, 70 or more, 75 or more, or in some cases 80 or more. The upper limit of x may be 97 or less, 95 or less, 90 or less, or in some cases 85 or less. The lower limit of y may be 2 or more, 3 or more, 4 or more, or in some cases 5 or more. The upper limit of y may be 30 or less, 25 or less, 20 or less, or in some cases 15 or less. The lower limit of z may be 1 or more, 1.5 or more, 2 or more, 3 or more, 4 or more, or in some cases 5 or more. The upper limit of z may be 45 or less, 30 or less, 15 or less, 12 or less, 10 or less, 9 or less, or in some cases 8 or less. The lower limit of x / y may be 3 or more, 4 or more, or in some cases 5 or more. The above upper and lower limits can be arbitrarily combined. Therefore, an example of the range of z is 4≦z≦9. Furthermore, the ranges of x, y, and z derived from the above can be arbitrarily combined.

[0019] The composition of the oxide for a solid electrolyte may be expressed by formula I, and Li3BO3, Li2SO4, and G do not need to be contained as they are. For example, when G consisting of elements M and O is contained, part of element M may actually exist as a composite oxide containing Li and M. However, composite oxides such as Li3BO3 may not be identified from an oxide that is an amorphous body in which no crystals are precipitated, even if the oxide has a composition that can be expressed by formula I.

[0020] The oxide for the solid electrolyte may contain other trace components in addition to the oxide that can be represented by Formula I. The trace components are, for example, Li halides and oxides containing elements not included in Formula I. The total content of the other trace components is, for example, less than 5%, less than 1%, less than 0.5%, or even less than 0.1% on a molar basis relative to 100% of the oxide represented by Formula I. The trace components may be components that are inevitably mixed in during mass production.

[0021] The oxide for the solid electrolyte may be a melt-solidified body. In other words, the oxide for the solid electrolyte of this embodiment can be produced by a melting method. As the melting method, various techniques known as methods for producing glass materials may be applied. A rapid cooling method called the twin roller method (twin roller quenching method) is also known as a method for producing glass materials. However, the oxide for the solid electrolyte of this embodiment can also be produced by a general melting method other than the twin roller method, which is more suitable for mass production.

[0022] Mechanical milling produces a processed product as a powder mixture or aggregate. This processed product, and the resulting solids obtained by pressing the processed product with other materials, differ in microstructure from melt-solidified materials.

[0023] The shape of the melt-solidified body is not particularly limited, but may be, for example, a sheet-like shape having a predetermined thickness. The predetermined thickness is, for example, 0.1 to 10 mm. However, the shape of the melt-solidified body may be changed by subsequent processing such as polishing, cutting, or pulverization. Although not particularly limited, an example of the average particle size D50 after pulverization or other micronization processing is 0.05 to 5 μm. The average particle size D50 is the particle size at the stage where the cumulative volume reaches 50% in measurement by laser diffraction scattering method.

[0024] The oxide for the solid electrolyte may be in a glass state. The oxide for the solid electrolyte may be a melt-solidified body and in a glass state. The oxide for the solid electrolyte may be in a glass ceramic state. The crystals contained in the oxide for the solid electrolyte in a glass ceramic state may include crystals precipitated by heat treatment. However, the oxide for the solid electrolyte may be an amorphous body in which precipitated crystals cannot be measured.

[0025] The oxide for the solid electrolyte may have a 90LiBO.10LiSO-based crystal. The 90LiBO.10LiSO-based crystal refers to a crystal that is similar to the 90LiBO.10LiSO-based solid electrolyte and exhibits a diffraction peak at substantially the same diffraction angle 2θ. The 90LiBO.10LiSO-based crystal may also be referred to as an ion-conductive LBO-LSO crystal phase.

[0026] X-ray diffraction analysis (CuKα, λ=1.5418 Å) of the 90LiBO.10LiSO-based solid electrolyte has at least the diffraction peaks specified in Patent Document 1, i.e., diffraction peaks at 2θ=21.5±0.5°, 2θ=23±0.5°, 2θ=28.5±0.5°, 2θ=29±0.5°, 2θ=32±0.5°, 2θ=36±0.5°, 2θ=38±0.5°, and 2θ=39.5±0.5°. The 90LiBO.10LiSO-based solid electrolyte also has diffraction peaks at 2θ=47.0±0.5° and 2θ=53.9±0.5°.

[0027] In this specification, when diffraction peaks are measured at diffraction angles 2θ of 60% or more, and even 70% or more of the total 10 diffraction angles 2θ described above, the oxide is evaluated as having diffraction peaks at diffraction angles 2θ that are "substantially the same" as those of the 90LiBO.10LiSO-based solid electrolyte. Some of the diffraction peaks of the crystals contained in the oxide for the solid electrolyte may not appear clearly, for example, if the heat treatment is insufficient.

[0028] The oxide for a solid electrolyte may be one that precipitates 90Li3BO3.10Li2SO4-based crystals by heat treatment H. Heat treatment H is a heat treatment carried out under conditions of 300°C or 310°C and 1 hour. Heat treatment H is carried out in the air. The oxide for a solid electrolyte may have 90Li3BO3.10Li2SO4-based crystals before heat treatment H, and the amount of the crystals may be increased by heat treatment H.

[0029] The solid electrolyte oxide may contain crystals other than 90Li3BO3.10Li2SO4-based crystals. One example is crystals derived from the addition of G. The crystals derived from G are, for example, Li4BO5 crystals. The solid electrolyte oxide may have Li4BO5 crystals. The solid electrolyte oxide may be one in which, by heat treatment H, Li4BO5 crystals that were not present before the heat treatment are precipitated.

[0030] The oxide for solid electrolyte may be used as a solid electrolyte as it is, or may be mixed with other materials or treated before use. The treatment includes heat treatment. The heat treatment can improve the ionic conductivity of the oxide for solid electrolyte. Other examples of the treatment include processing such as polishing, cutting, crushing, and press molding. The oxide for solid electrolyte may be used as a solid electrolyte as 10 -6 SCM -1 The electrical conductivity may be greater than .

[0031] [Method of Manufacturing Oxide for Solid Electrolyte] Next, a method of manufacturing an oxide for a solid electrolyte will be described as one embodiment of the present invention. This manufacturing method includes heating raw materials prepared so that the composition can be expressed by formula I to form a melt, and cooling the melt to obtain a solidified melt. Here, "so that the composition can be expressed by formula I" precisely means that the components excluding components that volatilize by heating have the composition of formula I.

[0032] When preparing the raw materials, known methods may be used to select and mix the individual materials that supply each component. Pre-prepared Li3BO3 crystals and Li2SO4 crystals may be blended into the raw materials. Mechanical milling is not required for mixing the individual materials; other common mixing methods may be used. Examples of heating temperatures for melting the raw materials include 700 to 1200°C, and even 800 to 1000°C. The heating time may be appropriately selected to obtain a uniform melt, and is, for example, 15 to 60 minutes. The raw materials may be melted in the atmosphere.

[0033] Thereafter, the melt, which is the melt of the raw materials, is cooled to form a solidified melt. In a typical melting method, for example, the melt is poured onto a support member, and if necessary, pressed from above with a pressing member, and cooled while maintaining contact with the support member, or the support member and the pressing member. The support member may function as a conveying member that conveys the melt or its solidified body while gradually cooling the melt. However, this is not limiting, and the melt or its solidified body can also be cooled while being conveyed by rollers arranged at predetermined intervals.

[0034] The cooling rate of the melt is not particularly limited and may be appropriately selected depending on the composition of the oxide to be produced and other factors, but may be, for example, 100 to 1000°C / sec, or further 200 to 600°C / sec. The cooling temperature of the melt is determined based on the heating temperature, i.e., the time required to cool from the melting temperature of the raw material to 200°C or below the crystal precipitation temperature.

[0035] The melt solidified body is then subjected to heat treatment as necessary. The heat treatment temperature is, for example, 200 to 400°C, or preferably 250 to 350°C. The heat treatment time is, for example, 1 minute to 10 hours, or preferably 5 minutes to 5 hours. The heat treatment can be carried out in the atmosphere, in dry air, or in an inert atmosphere such as N2 or Ar.

[0036] The melt solidified body is mixed with other materials or processed appropriately to be used as a solid electrolyte. The other materials may be other solid electrolytes. Examples of other solid electrolytes include lithium halides. The processing may be polishing, cutting, pulverization, press molding, etc. The oxide for the solid electrolyte may be used as a solid electrolyte itself, or may be pulverized and press molded to form a solid electrolyte.

[0037] The solid electrolyte can be used as a solid electrolyte layer constituting an electronic device typified by a secondary battery, a material constituting a part of a positive electrode or a negative electrode of a secondary battery, etc. The secondary battery may be an all-solid-state secondary battery.

[0038] As described above, the present disclosure provides the following techniques.

[0039] The first technology is an oxide for a solid electrolyte, the composition of which can be expressed by formula I. Formula I: xLi3BO3.yLi2SO4.zG, where G is at least one selected from the group consisting of B2O3, SiO2, Al2O3, PO5, GeO2, VO5, TeO2, Li3PO4, Li4B2O5, and Li2B4O7, and x, y, and z are numbers that satisfy 30≦x≦98, 1≦y≦40, 0.5≦z≦60, x / y≧2, and x+y+z=100.

[0040] The second technique is the oxide of the first technique, in which when the G is composed of only Li3PO4, the oxide is a melt-solidified body.

[0041] The third technology is the oxide of the first technology, in which G includes at least one selected from the group consisting of B2O3, SiO2, Al2O3, P2O5, GeO2, V2O5, and TeO2.

[0042] The fourth technology is the oxide of the third technology, in which G further contains Li3PO4.

[0043] The fifth technology is the oxide according to the first, third, or fourth technology, in which G includes at least two selected from the group consisting of B2O3, SiO2, Al2O3, PO5, GeO2, VO5, TeO2, Li3PO4, Li4B2O5, and Li2B4O7.

[0044] The sixth technology is the oxide according to any one of the first, third to fifth technologies, wherein G includes at least one selected from the group consisting of B2O3, SiO2, and Li3PO4.

[0045] A seventh technology is the oxide according to any one of the first to sixth technologies, in which the oxide is a melt-solidified body.

[0046] An eighth technology is the oxide according to any one of the first to seventh technologies, in which the oxide is in a glassy state.

[0047] The ninth technology is the oxide according to any one of the first to eighth technologies, which precipitates 90LiBO.10LiSO based crystals by heat treatment at 310°C for 1 hour, where the 90LiBO.10LiSO based crystals refer to crystals in which a diffraction peak is observed at substantially the same diffraction angle 2θ as that of the 90LiBO.10LiSO based solid electrolyte by X-ray diffraction analysis.

[0048] The tenth technology is the oxide according to any one of the first to eighth technologies, in which 90Li3BO3.10Li2SO4-based crystals are precipitated. The 90Li3BO3.10Li2SO4-based crystals have the meaning as described above.

[0049] The eleventh technology is the oxide according to any one of the first, third to fifth technologies, in which G contains B2O3 and Li4B2O5 ​​crystals are precipitated by heating at 310°C for 1 hour.

[0050] The twelfth technology is any one of the first, third to fifth oxides, in which G contains B2O3 and Li4B2O5 ​​crystals are precipitated.

[0051] The thirteenth technology is a method for producing an oxide for a solid electrolyte, comprising heating raw materials prepared so that the composition can be expressed by formula I to form a melt, and cooling the melt to obtain a solidified melt. Formula I: xLi3BO3.yLi2SO4.zG where G is at least one selected from the group consisting of BO, SiO, AlO, PO, GeO, VO, TeO, LiPO, LiBO, and LiBO, and x, y, and z are numbers that satisfy 30≦x≦98, 1≦y≦40, 0.5≦z≦60, x / y≧2, and x+y+z=100.

[0052] A fourteenth technique is the manufacturing method according to the thirteenth technique, further comprising heat-treating the solidified melt to precipitate 90LiBO.10LiSO-based crystals. The 90LiBO.10LiSO-based crystals have the meaning as described above.

[0053] A fifteenth technique is the manufacturing method according to the thirteenth technique, in which 90Li3BO3.10Li2SO4-based crystals are precipitated in the melt-solidified body. The 90Li3BO3.10Li2SO4-based crystals have the meaning as described above.

[0054] The sixteenth technology is a solid electrolyte containing an oxide according to any one of the first to twelfth technologies.

[0055] A seventeenth technique is a method for producing a solid electrolyte, which comprises heat-treating the oxide according to any one of the first to twelfth techniques.

[0056] An eighteenth technique is a method for producing a solid electrolyte, the method including carrying out the production method according to any one of the thirteenth to fifteenth techniques and heat-treating the melt-solidified body.

[0057] The present invention will be described in more detail below with reference to examples and comparative examples.

[0058] <Production of oxide for solid electrolyte> LiOH.H2O and H3BO3 were reacted, and then heated at 600°C for 2 hours in air to obtain Li3BO3 crystals. Separately, Li2SO4.H2O was thermally dried at 300°C for 2 hours in air or vacuum to obtain Li2SO4 crystals. All of the above raw materials were manufactured by Fujifilm Wako Pure Chemical Industries, Ltd.

[0059] LiBO crystals and LiSO crystals were mixed with LiCO (Showa Chemical), LiNO, LiPO (all Fujifilm Wako Pure Chemicals), BO (Nippon Denko), and SiO (Kojundo Chemical or Fumitec) to obtain the compositions shown in Tables 1 and 2 in mole percent. The mixtures were melted in a crucible at 1000°C (Examples 12-14), 900°C (Examples 1-3 and Comparative Examples 1-2), or 850°C (Examples 4-11 and Comparative Examples 3-9) for 30 minutes. Platinum, alumina, porcelain, or quartz crucibles were used. The melt was then poured onto a carbon, stainless steel, or copper plate and immediately pressed with a stainless steel iron from above to rapidly cool.

[0060] The thus obtained solidified melt body was observed from above, and the ratio of the vitrified region to the total region of the solidified melt body was evaluated by rounding it off to the nearest 10%. The results are shown in Tables 1 and 2.

[0061] The solidified melt was then heat-treated under the conditions of 310°C for 1 hour (Examples 1 to 3, 12 to 14, and Comparative Examples 1 and 2) or 300°C for 1 hour (Examples 4 to 11, and Comparative Examples 3 to 9). The heat treatment was carried out in the atmosphere.

[0062]

[0063]

[0064] (Characteristics Evaluation) X-ray diffraction analysis (CuKα radiation; λ=1.5418 Å), differential scanning calorimetry analysis, and Raman spectroscopy analysis were carried out for Examples 1 to 3 and Comparative Examples 1 and 2. Appropriate measurements were carried out on the melt-solidified body after quenching and before heat treatment (quenched product) and the melt-solidified body after heat treatment (heat-treated product).

[0065] Separately from the Examples and Comparative Examples, a sample was prepared by mechanically milling raw materials having the same composition as Comparative Example 1, with reference to Patent Document 1, and this sample was further heat-treated to obtain a 90LiBO.10LiSO-based solid electrolyte. X-ray diffraction analysis and Raman spectroscopy analysis were performed on the sample and solid electrolyte thus obtained.

[0066] In the X-ray diffraction pattern of the quenched product of Example 1, diffraction peaks were observed at the same diffraction angle as the 90LiBO·10LiSO-based solid electrolyte, suggesting that the 90LiBO·10LiSO-based solid electrolyte is present as the main phase. In the X-ray diffraction pattern of the heat-treated product of Example 1, the intensity of the diffraction peaks derived from the 90LiBO·10LiSO-based solid electrolyte increased and became sharper compared to before the heat treatment. In the quenched product of Example 2, diffraction peaks were observed at the same diffraction angle as the 90LiBO·10LiSO-based solid electrolyte. In addition to the diffraction peaks, a clear halo pattern was observed, indicating the presence of a large amount of amorphous phase. In Example 3, no crystal precipitation was observed in the quenched product, indicating that it was amorphous. However, when the quenched product of Example 3 was heat-treated at 310° C., a diffraction peak was confirmed at the same diffraction angle as that of the 90LiBO.10LiSO-based solid electrolyte. The presence of LiBO crystals was also confirmed in the X-ray diffraction patterns of the heat-treated products of Examples 2 and 3.

[0067] The X-ray diffraction patterns of the quenched samples of Examples 12 to 14 showed diffraction peaks at the same diffraction angles as the 90LiBO·10LiSO-based solid electrolyte, suggesting that the 90LiBO·10LiSO-based solid electrolyte is present as the main phase. In addition to the diffraction peaks, a clear halo pattern was also observed, indicating that the higher the SiO concentration, the more amorphous the phase. The heat-treated samples of Examples 12 to 14 were confirmed to have diffraction peaks substantially identical to those of the heat-treated 90LiBO·10LiSO-based solid electrolyte. Furthermore, the samples with higher SiO concentrations showed greater peak intensities at diffraction angles other than the maximum peak.

[0068] In addition, in the Raman spectrum, -1 BO3 3- Symmetric stretching of 1010 cm -1 SO4 2- In addition to the symmetrical expansion and contraction of 825 cm -1 B2O5 nearby 2- The Raman bands derived from B2O5 were confirmed in Example 3, which contained a larger amount of B2O3. 2- The intensity of the bands derived from the quenching increased. Furthermore, differential thermal analysis of the quenched products of Examples 2 and 3 confirmed the glass transition points (Tg) at 258°C (Example 2) and 268°C (Example 3), respectively, revealing the presence of a glass phase. Furthermore, crystallization peaks were confirmed at onset temperatures of 302°C (Example 2) and 310°C (Example 3). Further heating confirmed exothermic peaks at 390°C (Example 2) and 430°C (Example 3), suggesting a transition to a more stable crystalline phase. When heat-treated at 310°C, diffraction peaks were observed at the same diffraction angle as the 90Li3BO3.10Li2SO4-based solid electrolyte. Therefore, for example, heat treatment at a temperature between 300°C and 390°C, particularly 300°C to 350°C, is considered appropriate for the quenched product of Example 2.

[0069] From the Raman spectra of the quenched products of Examples 12 to 14, -1 BO3 3- Symmetric stretching of 1010 cm -1 SO4 2-In addition to the symmetrical expansion and contraction of 825 cm -1 B2O5 nearby 2- The Raman bands derived from B2O5 were confirmed, and the examples with a larger amount of SiO2 added showed 2- The intensity of the derived band increased.

[0070] In the quenched products of Comparative Examples 1 and 2, precipitation of Li3BO3 crystals and Li2SO4 crystals was relatively significant compared to Examples 1 to 3. In the quenched product of Comparative Example 1, XRD measurement confirmed strong, sharp crystalline phases attributable to Li3BO3 at 2θ = 21.2°, 30.0°, 32.8°, 35.6°, and 39.7°. In particular, the peak at 30.0° was more than three times stronger than the other peaks.

[0071] In the quenched product (unheat-treated sample) of the Reference Example to which the mechanical milling method was applied, no crystal precipitation was confirmed at the same composition as Comparative Example 1. From the heat-treated sample of the Reference Example, diffraction peaks of the 90LiBO.10LiSO-based solid electrolyte were confirmed.

[0072] Impedance measurements were carried out on some of the examples, and the conductivity at room temperature (25°C) was calculated. Samples were prepared by crushing the solidified melt and then press-molding. Press-molding was carried out under the following conditions: Pressing conditions: room temperature, 360 MPa, 0.1 hour. The measurement results before (quenched sample) and after (heat-treated sample) heat treatment are shown in Table 3.

[0073]

[0074] In conclusion, it was found that adding a third component (e.g., Li3PO4, SiO2, BO) to Li3BO3-Li2SO4 facilitates vitrification, or that a crystalline phase similar to the 90Li3BO3.10Li2SO4-based solid electrolyte is directly precipitated, resulting in an oxide-based solid electrolyte with high conductivity. In particular, a solid electrolyte in which a crystalline layer similar to the 90Li3BO3.10Li2SO4-based solid electrolyte is directly precipitated by quenching, or a solid electrolyte in which a crystalline phase similar to the 90Li3BO3.10Li2SO4-based solid electrolyte is precipitated by heat treatment at about 300°C after producing glass by quenching, exhibits high conductivity compared to 10 -6 SCM -1It was found that the material had a high conductivity exceeding 1000 kJ / cm.

Claims

1. An oxide for a solid electrolyte, the composition of which can be represented by formula I. Formula I: xLi3BO3.yLi2SO4.zG, where G is B2O3, SiO2, Al2O 3、 At least one selected from the group consisting of P2O5, GeO2, V2O5, TeO2, Li3PO4, Li4B2O5 ​​and Li2B4O7, and x, y and z are numbers that satisfy 30≦x≦98, 1≦y≦40, 0.5≦z≦60, x / y≧2 and x+y+z=100.

2. The oxide according to claim 1, wherein G consists solely of Li3PO4, and the oxide is a melt-solidified body.

3. The above G is B2O3, SiO2, Al2O 3、 2. The oxide according to claim 1, comprising at least one selected from the group consisting of P2O5, GeO2, V2O5 and TeO2.

4. The oxide of claim 3, wherein G further comprises Li3PO4.

5. The above G is B2O3, SiO2, Al2O 3、 2. The oxide according to claim 1, comprising at least two selected from the group consisting of P2O5, GeO2, V2O5, TeO2, Li3PO4, Li4B2O5 ​​and Li2B4O7.

6. The G is B2O3, SiO 2、 2. The oxide according to claim 1, comprising at least one selected from the group consisting of Li3PO4 and Li3PO4.

7. The oxide according to claim 1, wherein the oxide is a melt-solidified body.

8. The oxide of claim 1, wherein the oxide is in a glassy state.

9. The oxide according to claim 1, wherein 90Li3BO3·10Li2SO4-based crystals are precipitated by heat treatment at 310°C for 1 hour, whereby the 90Li3BO3·10Li2SO4-based crystals refer to crystals that exhibit a diffraction peak at substantially the same diffraction angle 2θ as that of the 90Li3BO3·10Li2SO4-based solid electrolyte by X-ray diffraction analysis.

10. The oxide according to claim 1, in which 90Li3BO3·10Li2SO4-based crystals are precipitated, where the 90Li3BO3·10Li2SO4-based crystals refer to crystals in which a diffraction peak is observed at substantially the same diffraction angle 2θ as that of the 90Li3BO3·10Li2SO4-based solid electrolyte by X-ray diffraction analysis.

11. The oxide according to claim 1, wherein G contains B2O3, and Li4B2O5 ​​crystals precipitate when heated at 310°C for 1 hour.

12. The oxide according to claim 1, wherein G contains B2O3 and Li4B2O5 ​​crystals are precipitated.

13. A method for producing an oxide for a solid electrolyte, comprising: heating raw materials prepared so that the composition can be expressed by formula I to form a melt; and cooling the melt to obtain a solidified melt. Formula I: xLi3BO3.yLi2SO4.zG, where G is at least one selected from the group consisting of B2O3, SiO2, Al2O3, PO5, GeO2, VO5, TeO2, Li3PO4, Li4B2O5, and Li2B4O7, and x, y, and z are numbers that satisfy 30≦x≦98, 1≦y≦40, 0.5≦z≦60, x / y≧2, and x+y+z=100.

14. The manufacturing method according to claim 13, further comprising heat-treating the solidified melt to precipitate 90Li3BO3.10Li2SO4-based crystals, wherein the 90Li3BO3.10Li2SO4-based crystals refer to crystals that exhibit, by X-ray diffraction, a diffraction peak at substantially the same diffraction angle 2θ as that of the 90Li3BO3.10Li2SO4 solid electrolyte.

15. The manufacturing method according to claim 13, wherein 90Li3BO3·10Li2SO4-based crystals are precipitated in the solidified melt, with the 90Li3BO3·10Li2SO4-based crystals meaning crystals that exhibit, by X-ray diffraction, a diffraction peak at substantially the same diffraction angle 2θ as that of the 90Li3BO3·10Li2SO4 solid electrolyte.

16. A solid electrolyte comprising the oxide according to any one of claims 1 to 12.

17. A method for producing a solid electrolyte, comprising heat treating the oxide according to any one of claims 1 to 12.

18. A method for producing a solid electrolyte, comprising: carrying out the production method according to any one of claims 13 to 15; and heat-treating the melt-solidified body.

Images