WO2019167813A1 - Li2B12H12およびLiBH4を含むイオン伝導体およびその製造方法、並びに該イオン伝導体を含む全固体電池用固体電解質 - Google Patents
Li2B12H12およびLiBH4を含むイオン伝導体およびその製造方法、並びに該イオン伝導体を含む全固体電池用固体電解質 Download PDFInfo
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- C01B—NON-METALLIC ELEMENTS; COMPOUNDS THEREOF; METALLOIDS OR COMPOUNDS THEREOF NOT COVERED BY SUBCLASS C01C
- C01B6/00—Hydrides of metals including fully or partially hydrided metals, alloys or intermetallic compounds ; Compounds containing at least one metal-hydrogen bond, e.g. (GeH3)2S, SiH GeH; Monoborane or diborane; Addition complexes thereof
- C01B6/06—Hydrides of aluminium, gallium, indium, thallium, germanium, tin, lead, arsenic, antimony, bismuth or polonium; Monoborane; Diborane; Addition complexes thereof
- C01B6/10—Monoborane; Diborane; Addition complexes thereof
- C01B6/13—Addition complexes of monoborane or diborane, e.g. with phosphine, arsine or hydrazine
- C01B6/15—Metal borohydrides; Addition complexes thereof
- C01B6/19—Preparation from other compounds of boron
- C01B6/21—Preparation of borohydrides of alkali metals, alkaline earth metals, magnesium or beryllium; Addition complexes thereof, e.g. LiBH4.2N2H4, NaB2H7
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Definitions
- the present invention relates to an ion conductor containing Li 2 B 12 H 12 and LiBH 4 , a method for producing the same, and a solid electrolyte for an all-solid-state battery including the ion conductor.
- lithium ion secondary batteries In recent years, demand for lithium ion secondary batteries has increased in applications such as portable information terminals, portable electronic devices, electric vehicles, hybrid electric vehicles, and stationary power storage systems.
- the current lithium ion secondary battery uses a flammable organic solvent as an electrolyte, and requires a strong exterior so that the organic solvent does not leak.
- the structure of the device such as the need to take a structure in preparation for the risk that the electrolyte should leak.
- ⁇ All solid-state batteries are broadly classified into thin film type and bulk type.
- interface bonding is ideally formed by using vapor deposition, but the electrode layer is as thin as several ⁇ m and the electrode area is small, and the energy stored per cell is small. The cost is also high. Therefore, it is not suitable as a battery for a large power storage device or an electric vehicle that needs to store a lot of energy.
- the thickness of the bulk-type electrode layer can be several tens to 100 ⁇ m, and an all-solid battery having a high energy density can be manufactured.
- Patent Documents 1 and 2 Among solid electrolytes, sulfides and complex hydrides have high ionic conductivity and are relatively soft, so they tend to form solid-solid interfaces, and are being studied for application to bulk-type all-solid-state batteries.
- sulfide solid electrolytes and complex hydride solid electrolytes have the property of reacting with water, sulfides generate hydrogen sulfide, complex hydrides generate hydrogen, and any solid electrolyte is water-soluble. After reacting with, there is a problem that the ionic conductivity decreases.
- complex hydride solid electrolytes tend to have slightly lower ionic conductivity than sulfide solid electrolytes, and improvements in ionic conductivity are also desired.
- Patent 6246816 WO2017-126416
- An object of the present invention is to provide an ionic conductor excellent in various properties such as water resistance and ionic conductivity, a method for producing the ionic conductor, and a solid electrolyte for an all-solid battery including the ionic conductor.
- the present inventors can solve the above problems by using an ionic conductor obtained by mixing LiBH 4 and B 10 H 14 at a specific molar ratio.
- ⁇ 3> The method for producing an ionic conductor according to ⁇ 1> or ⁇ 2>, including a step of subjecting the mixture to a mechanical milling process before the heat treatment step.
- ⁇ 4> The method for producing an ionic conductor according to ⁇ 3>, wherein the mechanical milling treatment is performed for 0.5 to 7 hours.
- ⁇ 5> The method for producing an ion conductor according to ⁇ 3> or ⁇ 4>, including a step of performing a second mechanical milling treatment after the heat treatment step.
- ⁇ 6> The method for producing an ionic conductor according to ⁇ 5>, wherein the second mechanical milling is performed for 10 to 30 hours.
- the obtained ionic conductor has at least ⁇ 15.6 ppm ( ⁇ 1 ppm), ⁇ 17.6 ppm ( ⁇ 1 ppm), ⁇ 1.7 ppm and ⁇ 29.4 ppm ( ⁇ 1. 5) in B 11 MAS NMR measurement. 5 ppm) and ⁇ 42.0 ppm ( ⁇ 2 ppm), peak A is ⁇ 15.6 ppm ( ⁇ 1 ppm), and peak B is ⁇ 42.0 ppm ( ⁇ 2 ppm).
- ⁇ 8> including a step of molding in an atmosphere having a dew point of ⁇ 30 ° C. to ⁇ 80 ° C. using the ion conductor obtained by the method for producing an ion conductor according to any one of ⁇ 1> to ⁇ 7>
- This is a method for producing an all-solid battery.
- An ionic conductor containing Li 2 B 12 H 12 and LiBH 4 which is at least ⁇ 15.6 ppm ( ⁇ 1 ppm), ⁇ 17.6 ppm ( ⁇ 1 ppm), ⁇ 1.
- B 11 MAS NMR measurement In B 11 MAS NMR measurement.
- the ionic conductor has an intensity ratio (B / A) of peak B to peak A in the range of 0.1 to 2.0.
- an ionic conductor excellent in various properties such as water resistance and ionic conductivity a method for producing the ionic conductor, and a solid electrolyte for an all-solid battery including the ionic conductor can be provided.
- FIG. 1A shows X-ray diffraction peaks of the ion conductor powders obtained in Examples 1 and 2 and Comparative Examples 1 to 4.
- FIG. 1B is an enlarged view of a diffraction peak of a part (Examples 1 and 2 and Comparative Examples 1 and 2) of FIG. 1A.
- FIG. 1C shows X-ray diffraction peaks in the powder of the ionic conductor obtained in Examples 2 and 3.
- FIG. 2A shows the results of B 11 MAS NMR measurement of the ion conductor powders obtained in Examples 1 and 2 and Comparative Example 2.
- FIG. 2A shows the result of B 11 MAS NMR measurement in the powder of the ion conductor obtained in Example 2 and Comparative Example 1.
- FIG. 3 shows the results of ion conductivity measurement in the ion conductors obtained in Examples 1 to 3 and Comparative Examples 1 to 6.
- Ionic Conductor comprising Li 2 B 12 H 12 and LiBH 4 , [B 12 H 12 ] 2 ⁇ and [B 11 H 11 ] 2 ⁇ and [B 10 H 10 as anions. ] 2- and [BH 4] - and ion conductor comprising is provided.
- the ionic conductor of the present invention is characterized by containing borohydride (BH 4 ⁇ ).
- BH 4 - a high content ionic conductivity is high in, but since the water resistance is lowered, it is possible to those of the physical properties desired by adjusting the content so that the desired physical properties.
- the ion conductor of the present invention has a peak of ⁇ 15.6 ppm ( ⁇ 1 ppm) based on [B 12 H 12 ] 2 ⁇ A and a peak of ⁇ 42.0 ppm ( ⁇ 2 ppm) based on [BH 4 ] ⁇
- the intensity ratio of peak B to peak A (B / A) is in the range of 0.1 to 2.0, preferably in the range of 0.2 to 1.5, A range is more preferred.
- the ion conductor of this invention may contain components other than lithium (Li), boron (B), and hydrogen (H).
- other components include oxygen (O), nitrogen (N), sulfur (S), fluorine (F), chlorine (Cl), bromine (Br), iodine (I), silicon (Si), germanium ( Ge), phosphorus (P), alkali metal, alkaline earth metal and the like.
- X-ray diffraction peaks at 0.8 deg, 31.0 ⁇ 0.8 deg and 32.5 ⁇ 0.8 deg, and more preferably at least 2 ⁇ 16.1 ⁇ 0.5 deg, 18.6 ⁇ 0.5 deg 24.0 ⁇ 0.5 deg, 24.9 ⁇ 0.8 deg, 27.0 ⁇ 0.8 deg, 31.0 ⁇ 0.8 deg, 32.5 ⁇ 0.8 deg, 37.7 ⁇ 1.0 deg, 38 X-ray diffraction peaks at .9 ⁇ 1.0 deg, 41.2 ⁇ 1.2 deg and 43.5 ⁇ 1.2 deg.
- a desired effect is acquired.
- the above ionic conductor has excellent ionic conductivity.
- the X-ray diffraction peaks as described above correspond to diffraction peaks derived from the crystal structures of Li 2 B 12 H 12 and LiBH 4 . Since the peak intensity of Li 2 B 12 H 12 is strong, there are a plurality of anion species, but it is considered that many of them are dissolved in the Li 2 B 12 H 12 crystal. [B 12 H 12 ] 2 ⁇ is different from BH 4 ⁇ in that the decomposition rate with water is very slow, so the stability to water is extremely high, and when water is present, it forms hydrates and exists as stable crystals. To do. Therefore, even when an unstable anion such as BH 4 ⁇ is mixed in [B 12 H 12 ] 2 ⁇ , the water resistance can be greatly improved.
- the ionic conductor is soft like LiBH 4 solid electrolyte and can be formed into an electrode layer and a solid electrolyte layer by cold pressing. And the electrode layer and solid electrolyte layer which were formed in this way are excellent in intensity
- the raw material LiBH 4 As the raw material LiBH 4 , a commercially available product can be used. Moreover, the purity is preferably 80% or more, and more preferably 90% or more. By using a compound having a purity within the above range, desired crystals can be easily obtained.
- the B 10 H 14, which is the other starting material, can be used those commercially available normally. The purity of B 10 H 14 is preferably 95% or more, and more preferably 97% or more.
- the ion conductivity can be increased by containing a large amount of LiBH 4 as a raw material. Conversely, when LiBH 4 is reduced, the water resistance can be improved.
- the molar ratio of LiBH 4 / B 10 H 14 is preferably in the range of 2.3 to 4.1, More preferably, it is 2.5 to 4.0.
- LiBH 4 and B 10 H 14 are preferably performed in an inert gas atmosphere.
- the inert gas include helium, nitrogen, and argon, and argon is more preferable.
- the concentration of moisture and oxygen in the inert gas is preferably controlled to be low, and more preferably, the concentration of moisture and oxygen in the inert gas is less than 1 ppm.
- the mixing method is not particularly limited, and stirring and mixing in a solvent can be used.
- Mechanical mixing can also be used, and examples thereof include a method using a reiki machine, a ball mill, a planetary ball mill, a bead mill, a self-revolving mixer, a high-speed stirring type mixing apparatus, a tumbler mixer, and the like. Among these, a planetary ball mill having excellent crushing power and mixing power is more preferable.
- the mechanical mixing is preferably performed by a dry method, but can also be performed in a solvent having reduction resistance. Regardless of the above method, when a solvent is used, an aprotic non-aqueous solvent is preferable. More specifically, ether solvents such as tetrahydrofuran and diethyl ether, acetonitrile, N, N-dimethylformamide, N, N -Dimethylacetamide and the like.
- the mixing time varies depending on the mixing method, but in the case of stirring and mixing in a solvent, for example, it is 0.1 to 48 hours, and preferably 1 to 24 hours.
- a solvent capable of dissolving one of the raw materials for example, an ether solvent such as tetrahydrofuran or diethyl ether, acetonitrile, N, N-dimethylformamide, N, N-dimethylacetamide or the like that can dissolve LiBH 4 is used. If so, the mixing time can be shortened.
- the mixing time in the mechanical mixing for example, when a planetary ball mill is used, it is 0.5 to 24 hours, and preferably 2 to 20 hours.
- the purpose is to uniformly disperse the raw material and it is not necessary to cause a reaction. Therefore, when the obtained mixture is subjected to X-ray diffraction measurement, peaks of LiBH 4 and B 10 H 14 which are raw materials can be confirmed.
- the reaction proceeds by heating the mixture as described above, and the ion conductor of the present invention can be obtained.
- the heating temperature is usually preferably in the range of 100 to 300 ° C., more preferably in the range of 150 to 250 ° C., and particularly preferably 170 to 230 ° C. If the temperature is lower than the above range, desired crystals are hardly formed. On the other hand, if the temperature is higher than the above range, the ionic conductor may be deteriorated.
- the heating time varies slightly depending on the heating temperature, it is usually sufficiently crystallized in the range of 3 to 40 hours.
- the heating time is preferably 5 to 30 hours, more preferably 10 to 20 hours. It is not preferable to heat at a high temperature for a long time because there is a concern about deterioration of the ionic conductor.
- the heat treatment is preferably performed in an inert gas atmosphere.
- the inert gas include helium, nitrogen, and argon, and argon is more preferable.
- the concentration of moisture and oxygen in the inert gas is preferably controlled to be low, and more preferably, the concentration of moisture and oxygen in the inert gas is less than 1 ppm.
- the reaction pressure is usually in the range of 0.1 Pa to 3 MPa as an absolute pressure.
- the pressure is slightly higher than the normal pressure, the decomposition of the ionic conductor due to the desorption of hydrogen tends to be suppressed, more preferably 101 kPa to 1 MPa, and particularly preferably in the range of 0.11 MPa to 0.5 MPa. .
- the ion conductivity can also be improved by subjecting the mixture to a mechanical milling treatment before the heat treatment step.
- the time for performing the first mechanical milling treatment is preferably 0.5 to 7 hours, more preferably 1 to 6 hours, and particularly preferably 3 to 5 hours.
- the ionic conductor can be further improved by subjecting the ionic conductor obtained as described above to a second mechanical milling treatment.
- the mechanical milling time is preferably 10 to 30 hours, more preferably 15 to 25 hours, and particularly preferably 18 to 22 hours.
- the method of the first and second mechanical milling processes is not particularly limited, and examples thereof include a vibration mill and a planetary ball mill.
- the ionic conductor obtained by the above production method of the present invention has at least ⁇ 15.6 ppm ( ⁇ 1 ppm), ⁇ 17.6 ppm ( ⁇ 1 ppm), and ⁇ 29.4 ppm ( ⁇ 1.5 ppm) in the B 11 MAS NMR measurement. ) And ⁇ 42.0 ppm ( ⁇ 2 ppm), peak A is ⁇ 15.6 ppm ( ⁇ 1 ppm), and peak B is ⁇ 42.0 ppm ( ⁇ 2 ppm).
- the intensity ratio (B / A) is preferably in the range of 0.1 to 2.0.
- All-solid battery The ion conductor of the present invention can be used as a solid electrolyte for an all-solid battery. Therefore, according to one embodiment of the present invention, a solid electrolyte for an all-solid battery including the above-described ion conductor is provided. Moreover, according to the further embodiment of this invention, the all-solid-state battery using the solid electrolyte for all-solid-state batteries mentioned above is provided.
- an all solid state battery is an all solid state battery in which lithium ions are responsible for electrical conduction, and in particular, is an all solid state lithium ion secondary battery.
- the all solid state battery has a structure in which a solid electrolyte layer is disposed between a positive electrode layer and a negative electrode layer.
- the ion conductor of the present invention may be contained as a solid electrolyte in any one or more of the positive electrode layer, the negative electrode layer, and the solid electrolyte layer. When used for the electrode layer, it is preferably used for the positive electrode layer rather than the negative electrode layer. This is because a side reaction is less likely to occur in the positive electrode layer.
- the positive electrode layer or the negative electrode layer contains the ion conductor of the present invention
- the ion conductor and a known positive electrode active material or negative electrode active material for a lithium ion secondary battery are used in combination.
- the positive electrode layer it is preferable to use a bulk type in which an active material and a solid electrolyte are mixed because the capacity per unit cell is increased.
- the all solid state battery is manufactured by molding and laminating the above-mentioned layers, but the molding method and laminating method of each layer are not particularly limited.
- a vapor phase method in which a film is formed and laminated using a method, a sputtering method, a laser ablation method, etc .
- a press method in which powder is formed by hot pressing or cold pressing without applying temperature, and then laminated.
- the positive electrode layer can also be formed using a sol-gel method.
- an electrode layer containing an active material, a conductive additive, and binders is formed in advance, and a solution in which a solid electrolyte is dissolved in a solvent or a slurry in which a solid electrolyte is dispersed in a solvent are poured into the electrode layer. It is also possible to incorporate a solid electrolyte into the electrode layer by removing.
- the atmosphere for producing the all solid state battery is carried out in an inert gas or dry room in which moisture is controlled.
- the dew point is in the range of ⁇ 20 ° C. to ⁇ 100 ° C., more preferably in the range of ⁇ 30 ° C. to ⁇ 80 ° C., and particularly preferably in the range of ⁇ 40 ° C. to ⁇ 75 ° C.
- LiBH 4 manufactured by Sigma-Aldrich, purity ⁇ 95%)
- B 10 H 14 manufactured by Wako Pure Chemical Industries, Ltd., purity ⁇ 99.0%
- This pot was attached to a planetary ball mill (P7 made by Fritche), and the raw materials were mixed by mechanical milling at a rotational speed of 400 rpm for 5 hours. Thereafter, argon confined atmosphere, by applying a 15 hour heat treatment at 200 ° C., to obtain an ionic conductor containing Li 2 B 12 H 12 and LiBH 4.
- Example 3 In a glove box under an argon atmosphere, 100 mg of the ionic conductor obtained in Example 2 was weighed and put into a 45 mL SUJ-2 pot, and SUJ-2 balls ( ⁇ 7 mm, 20 pieces) were further added. The pot was completely sealed. This pot was attached to a planetary ball mill (P7 made by Fritche) and subjected to a second mechanical milling process at a rotation speed of 400 rpm for 20 hours to obtain an ion conductor containing Li 2 B 12 H 12 and LiBH 4 . .
- P7 made by Fritche
- FIGS. 1A to 1C show X-ray diffraction peaks of LiBH 4 and B 10 H 14 as raw materials.
- FIG. 1C shows the X-ray diffraction peaks of the ionic conductor powders obtained in Examples 2 and 3.
- Example 3 although the intensity
- ⁇ Ion conductivity measurement> In a glove box under an argon atmosphere, the ionic conductors obtained in Examples 1 to 3 and Comparative Examples 1 to 6 were subjected to uniaxial molding (240 MPa) to produce a disc having a thickness of about 1 mm and ⁇ 8 mm. The temperature is raised and lowered at 10 ° C intervals from room temperature to 150 ° C or 80 ° C, and AC impedance measurement (HIOKI 3532-80, chemical impedance meter) is performed by a two-terminal method using a lithium electrode, and the ionic conductivity is measured. Calculated. The measurement frequency range was 4 Hz to 1 MHz, and the amplitude was 100 mV.
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Abstract
Description
例えば、全固体リチウムイオン二次電池における固体電解質として、酸化物、リン酸化合物、有機高分子、硫化物、錯体水素化物等を使用することが検討されている。
<1> Li2B12H12およびLiBH4を含むイオン伝導体の製造方法であって、
LiBH4とB10H14とを、LiBH4/B10H14=2.1~4.3のモル比で混合して混合物を得る工程、及び
前記混合物を加熱処理する工程を含む、前記イオン伝導体の製造方法である。
<2> 前記加熱処理の温度が100~300℃である、上記<1>に記載のイオン伝導体の製造方法である。
<3> 前記加熱処理する工程の前に、前記混合物にメカニカルミリング処理を施す工程を含む、上記<1>または<2>に記載のイオン伝導体の製造方法である。
<4> 前記メカニカルミリング処理を施す時間が0.5~7時間である、上記<3>に記載のイオン伝導体の製造方法である。
<5> 前記加熱処理する工程の後に、2回目のメカニカルミリング処理を施す工程を含む、上記<3>または<4>に記載のイオン伝導体の製造方法である。
<6> 前記2回目のメカニカルミリング処理を施す時間が10~30時間である、上記<5>に記載のイオン伝導体の製造方法である。
<7> 得られたイオン伝導体が、B11MAS NMR測定において、少なくとも-15.6ppm(±1ppm)、-17.6ppm(±1ppm)、-1.7ppmおよび-29.4ppm(±1.5ppm)、並びに-42.0ppm(±2ppm)にピークを有し、-15.6ppm(±1ppm)をピークA、-42.0ppm(±2ppm)をピークBとしたとき、ピークAに対するピークBの強度比(B/A)が0.1~2.0の範囲である、上記<1>から<6>のいずれかに記載のイオン伝導体の製造方法である。
<8> 上記<1>から<7>のいずれかに記載のイオン伝導体の製造方法によって得られたイオン伝導体を用い、露点-30℃~-80℃の雰囲気下で成形する工程を含む、全固体電池の製造方法である。
<9> Li2B12H12およびLiBH4を含むイオン伝導体であって、B11MAS NMR測定において、少なくとも-15.6ppm(±1ppm)、-17.6ppm(±1ppm)、-1.7ppmおよび-29.4ppm(±1.5ppm)、並びに-42.0ppm(±2ppm)にピークを有し、-15.6ppm(±1ppm)をピークA、-42.0ppm(±2ppm)をピークBとしたとき、ピークAに対するピークBの強度比(B/A)が0.1~2.0の範囲である、前記イオン伝導体である。
<10> 少なくとも2θ=16.1±0.5deg、18.6±0.5deg、24.0±0.5deg、24.9±0.8deg、27.0±0.8deg、31.0±0.8degおよび32.5±0.8degにX線回折ピークを有する、上記<9>に記載のイオン伝導体である。
<11> 上記<9>または<10>に記載のイオン伝導体を含む全固体電池用固体電解質である。
本発明の1つの実施形態によると、Li2B12H12およびLiBH4を含み、アニオンとして[B12H12]2-と[B11H11]2-と[B10H10]2-と[BH4]-とを含むイオン伝導体が提供される。これらのアニオンはB11MAS NMR測定において、[B12H12]2-は-15.6ppm(±1ppm)、[B11H11]2-は-17.6ppm(±1ppm)、[B10H10]2―は-1.7ppmおよび-29.4ppm(±1.5ppm)、[BH4]―は-42.0ppm(±2ppm)にそれぞれピークを有する。
また、本発明のイオン伝導体は、リチウム(Li)とホウ素(B)と水素(H)以外の成分を含んでいてもよい。他の成分としては、例えば、酸素(O)、窒素(N)、硫黄(S)、フッ素(F)、塩素(Cl)、臭素(Br)、ヨウ素(I)、ケイ素(Si)、ゲルマニウム(Ge)、リン(P)、アルカリ金属、アルカリ土類金属等が挙げられる。
上述した本発明のイオン伝導体は、LiBH4とB10H14とを、LiBH4/B10H14=2.1~4.3のモル比で混合して混合物を得る工程、及び前記混合物を加熱処理する工程を含む方法によって製造することができる。
本発明のイオン伝導体は、全固体電池用の固体電解質として使用され得る。よって、本発明の一実施形態によると、上述したイオン伝導体を含む全固体電池用固体電解質が提供される。また、本発明のさらなる実施形態によると、上述した全固体電池用固体電解質を使用した全固体電池が提供される。
(実施例1)
アルゴン雰囲気下のグローブボックス内で、LiBH4(シグマ・アルドリッチ社製、純度≧95%)とB10H14(和光純薬工業株式会社製、純度≧99.0%)とを、LiBH4:B10H14=4:1のモル比になるように100mg量り取り、メノウ乳鉢にて予備混合した。次に、予備混合した原料を45mLのSUJ-2製ポットに投入し、さらにSUJ-2製ボール(φ7mm、20個)を投入して、ポットを完全に密閉した。このポットを遊星型ボールミル機(フリッチェ製P7)に取り付け、回転数400rpmで5時間、メカニカルミリングにより原料を混合した。その後、アルゴン密閉雰囲気下、200℃にて15時間加熱処理を施すことにより、Li2B12H12およびLiBH4を含むイオン伝導体を得た。
LiBH4とB10H14との混合モル比をLiBH4:B10H14=3:1へと変更したことを除き、実施例1と同様にイオン伝導体を製造した。
アルゴン雰囲気下のグローブボックス内で、実施例2で得られたイオン伝導体を100mg量り取り、45mLのSUJ-2製ポットに投入し、さらにSUJ-2製ボール(φ7mm、20個)を投入して、ポットを完全に密閉した。このポットを遊星型ボールミル機(フリッチェ製P7)に取り付け、回転数400rpmで20時間、2回目のメカニカルミリング処理を施すことにより、Li2B12H12およびLiBH4を含むイオン伝導体を得た。
Li2B12H12・4H2O(Katchem社製)を、真空雰囲気下、225℃にて20時間加熱処理を施すことにより、Li2B12H12を含むイオン伝導体を得た。
LiBH4とB10H14との混合モル比を以下のように変更したことを除き、実施例1と同様にイオン伝導体を製造した。モル比をLiBH4:B10H14=2:1(比較例2)、1.5:1(比較例3)、1:1(比較例4)とした。
イオン伝導体を比較例2で得られたもの(比較例5)および比較例4で得られたもの(比較例6)へと変更したことを除き、実施例3と同様に2回目のメカニカルミリング処理を施すことにより、イオン伝導体を製造した。
実施例1~3および比較例1~4で得られたイオン伝導体の粉末について、アルゴン雰囲気下、室温にて、X線回折測定(PANalytical社製X‘pert Pro、CuKα:λ=1.5405Å)を実施した。得られたX線回折ピークを図1A~図1Cに示す。図1Aには比較のため、原料であるLiBH4およびB10H14のX線回折ピークも示す。図1Cには、実施例2および3で得られたイオン伝導体の粉末のX線回折ピークを示した。
実施例1~2では、少なくとも、2θ=16.1±0.5deg、18.6±0.5deg、24.0±0.5deg、24.9±0.8deg、27.0±0.8deg、31.0±0.8degおよび32.5±0.8degにX線回折ピークが観測された。実施例3においては、X線回折ピークの強度が小さくなっているが、わずかながら上述したX線回折ピークを確認できる。メカニカルミリング処理を施したことにより、結晶粒子が小さくなったため、ピーク強度が小さくなったと考えられる。
実施例1~2および比較例1~2で得られたイオン伝導体の粉末について、大気非暴露試料管(日本電子社製3.2mmシーリング試料管)を用いて、B11MAS NMR測定(日本電子社製ECA500)を実施した。なお、測定条件は、MAS回転10kHz、リファレンス (C2H5)2OBF3、待ち時間 Saturation recovery法により求めたT1×4~5倍(秒)にて行った。結果を図2Aおよび図2Bに示す。実施例1~2および比較例1~2においては、いずれも[B12H12]2-は-15.6ppm(±1ppm)、[B11H11]2-は-17.6ppm(±1ppm)、[B10H10]2―は-1.7ppmおよび-29.4ppm(±1.5ppm)、にそれぞれピークが観測された。実施例1および2においては上記のピークの他に、[BH4]―に基づく-42.0ppm[±2ppm]のピークが明確に観測された。-15.6ppm(±1ppm)をピークA、-42.0ppm(±2ppm)をピークBとしたとき、ピークAに対するピークBの強度比(B/A)は、実施例1では1.17であり、実施例2では0.48であり、比較例2では0.05であった。
アルゴン雰囲気下のグローブボックス内で、実施例1~3および比較例1~6で得られたイオン伝導体を一軸成型(240MPa)に供し、厚さ約1mm、φ8mmのディスクを製造した。室温から150℃もしくは80℃の温度範囲において10℃間隔で昇温・降温させ、リチウム電極を利用した二端子法による交流インピーダンス測定(HIOKI 3532-80、chemical impedance meter)を行い、イオン伝導度を算出した。測定周波数範囲は4Hz~1MHz、振幅は100mVとした。
露点-40℃~-75℃のドライルーム内で、実施例3で得られたイオン伝導体、比較例1で得られたLi2B12H12、および3LiBH4-LiIを6時間大気暴露させた。この時のドライルームの露点の推移を表1に記載した。大気暴露の後、イオン伝導度測定を行い、各サンプルの暴露前後におけるイオン伝導度(25℃)の比較を行った結果を表2に示す。同じ錯体水素化物系固体電解質でも3LiBH4-LiIは1/20にイオン伝導度が低下したが、実施例3で得られたイオン伝導体および比較例1で得られたLi2B12H12については、イオン伝導度の劣化が生じなかった。
Claims (11)
- Li2B12H12およびLiBH4を含むイオン伝導体の製造方法であって、
LiBH4とB10H14とを、LiBH4/B10H14=2.1~4.3のモル比で混合して混合物を得る工程、及び
前記混合物を加熱処理する工程を含む、前記イオン伝導体の製造方法。 - 前記加熱処理の温度が100~300℃である、請求項1に記載のイオン伝導体の製造方法。
- 前記加熱処理する工程の前に、前記混合物にメカニカルミリング処理を施す工程を含む、請求項1または2に記載のイオン伝導体の製造方法。
- 前記メカニカルミリング処理を施す時間が0.5~7時間である、請求項3に記載のイオン伝導体の製造方法。
- 前記加熱処理する工程の後に、2回目のメカニカルミリング処理を施す工程を含む、請求項3または4に記載のイオン伝導体の製造方法。
- 前記2回目のメカニカルミリング処理を施す時間が10~30時間である、請求項5に記載のイオン伝導体の製造方法。
- 得られたイオン伝導体が、B11MAS NMR測定において、少なくとも-15.6ppm(±1ppm)、-17.6ppm(±1ppm)、-1.7ppmおよび-29.4ppm(±1.5ppm)、並びに-42.0ppm(±2ppm)にピークを有し、-15.6ppm(±1ppm)をピークA、-42.0ppm(±2ppm)をピークBとしたとき、ピークAに対するピークBの強度比(B/A)が0.1~2.0の範囲である、請求項1から6のいずれかに記載のイオン伝導体の製造方法。
- 請求項1から7のいずれかに記載のイオン伝導体の製造方法によって得られたイオン伝導体を用い、露点-30℃~-80℃の雰囲気下で成形する工程を含む、全固体電池の製造方法。
- Li2B12H12およびLiBH4を含むイオン伝導体であって、B11MAS NMR測定において、少なくとも-15.6ppm(±1ppm)、-17.6ppm(±1ppm)、-1.7ppmおよび-29.4ppm(±1.5ppm)、並びに-42.0ppm(±2ppm)にピークを有し、-15.6ppm(±1ppm)をピークA、-42.0ppm(±2ppm)をピークBとしたとき、ピークAに対するピークBの強度比(B/A)が0.1~2.0の範囲である、前記イオン伝導体。
- 少なくとも2θ=16.1±0.5deg、18.6±0.5deg、24.0±0.5deg、24.9±0.8deg、27.0±0.8deg、31.0±0.8degおよび32.5±0.8degにX線回折ピークを有する、請求項9に記載のイオン伝導体。
- 請求項9または10に記載のイオン伝導体を含む全固体電池用固体電解質。
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KR1020207026947A KR102692199B1 (ko) | 2018-02-28 | 2019-02-22 | Li2B12H12 및 LiBH4를 포함하는 이온 전도체 및 그의 제조 방법, 및 해당 이온 전도체를 포함하는 전고체 전지용 고체 전해질 |
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