JP2017040531A - Measurement method of water amount in sulfide solid state electrolyte - Google Patents

Measurement method of water amount in sulfide solid state electrolyte Download PDF

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JP2017040531A
JP2017040531A JP2015161786A JP2015161786A JP2017040531A JP 2017040531 A JP2017040531 A JP 2017040531A JP 2015161786 A JP2015161786 A JP 2015161786A JP 2015161786 A JP2015161786 A JP 2015161786A JP 2017040531 A JP2017040531 A JP 2017040531A
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泰正 小熊
Yasumasa Oguma
泰正 小熊
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Toyota Motor Corp
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Abstract

PROBLEM TO BE SOLVED: To provide a measurement method of water amount in a well-conditioned sulfide solid state electrolyte.SOLUTION: On the basis of the fact that water of 1 mole reacts with sulfide solid state electrolyte resulting in hydrogen sulfide of 1 mole, and both of hydrogen sulfide and water react with iodine of equal mole in Karl-Fischer method, the measurement method of water amount in a sulfide solid state electrolyte measures the water amount by applying Karl-Fischer method conforming to JIS K2275 while heating the sulfide solid state electrolyte to a temperature to a crystallization temperature or more and a decomposition temperature or less.SELECTED DRAWING: Figure 4

Description

本発明は、カールフィッシャー法を用いた、硫化物系固体電解質中の水分量の測定方法に関する。   The present invention relates to a method for measuring the amount of water in a sulfide-based solid electrolyte using the Karl Fischer method.

近年、従来の液体電解質を使用したリチウム二次電池に代えて、固体電解質二次電池を用いることにより、安全装置の簡素化、製造コストの低下、生産性をさらに向上させることなどが検討されている。   In recent years, it has been studied to use a solid electrolyte secondary battery instead of a conventional lithium secondary battery using a liquid electrolyte to simplify safety devices, reduce manufacturing costs, and further improve productivity. Yes.

固体電解質二次電池に用いる電解質の中でも、リチウムイオンの伝導性に優れる硫化物系固体電解質が注目されている。   Of the electrolytes used in the solid electrolyte secondary battery, a sulfide-based solid electrolyte having excellent lithium ion conductivity has attracted attention.

しかし、硫化物系固体電解質材料は、水分と反応しやすく、さらに水分との反応で発生する硫化水素により劣化しやすい。そうしたことから硫化物系固体電解質中の水分量を管理することは重要である。   However, sulfide-based solid electrolyte materials are likely to react with moisture and further deteriorate due to hydrogen sulfide generated by the reaction with moisture. Therefore, it is important to control the amount of water in the sulfide-based solid electrolyte.

従来、水分量の測定は、材料を加熱して発生するガスを質量分析することなどにより行っていた。しかし、ガス質量分析では、設備のコストが高く、測定時間も長かった。   Conventionally, the amount of moisture has been measured by mass analysis of gas generated by heating a material. However, gas mass spectrometry has a high equipment cost and a long measurement time.

一方、カールフィッシャー法による水分量の測定は、ガス質量分析装置と比較して、簡便且つ低コストで測定できるため、材料の水分量の管理手段として使用されてきた。   On the other hand, the measurement of the moisture content by the Karl Fischer method has been used as a means for managing the moisture content of a material because it can be measured easily and at a lower cost than a gas mass spectrometer.

特許文献1は、正極活物質の水分量を測定するために、正極活物質であるリチウム複合酸化物を180℃に加熱して気化させた水分を、カールフィッシャー法を用いて測定することを記載する(特許文献1、請求項1、2、明細書中段落[0065]など)。   Patent Document 1 describes that in order to measure the moisture content of the positive electrode active material, the moisture obtained by heating and vaporizing the lithium composite oxide as the positive electrode active material to 180 ° C. is measured using the Karl Fischer method. (Patent Document 1, Claims 1 and 2, paragraph [0065] in the specification, etc.).

特許文献2は、リチウムイオン伝導性を呈する無機酸化物の粉末及び有機バインダを含むグリーンシートの含水量を、200℃に加熱した際に放出される水蒸気を、カールフィッシャー法を用いて測定する方法を記載する(特許文献2、請求項1、明細書中段落[0010],[0059]〜[0063]など)。   Patent Document 2 discloses a method for measuring water vapor released when a water content of a green sheet containing an inorganic oxide powder exhibiting lithium ion conductivity and an organic binder is heated to 200 ° C. using a Karl Fischer method. (Patent Document 2, Claim 1, paragraphs [0010], [0059] to [0063], etc. in the specification).

特許文献3は、カールフィッシャー水分計を用いて硫化物系固体電解質材料を酸化してできた酸化物層中の水分含有量を測定する方法を記載する(特許文献3、明細書中段落[0034]、[0035]など)。   Patent Document 3 describes a method of measuring the water content in an oxide layer formed by oxidizing a sulfide-based solid electrolyte material using a Karl Fischer moisture meter (Patent Document 3, paragraph [0034] in the specification). ], [0035], etc.).

特許文献4は、セラミック焼結体を200℃に加熱して水分を気化させて、カールフィッシャー試薬を用いて滴定して水分量を測定する方法を記載する(特許文献4、請求項1など)。   Patent Document 4 describes a method in which a ceramic sintered body is heated to 200 ° C. to vaporize water, and titrated with a Karl Fischer reagent to measure the amount of water (Patent Document 4, Claim 1, etc.). .

しかし、従来技術では、酸化等されていない硫化物系固体電解質中の含水量を具体的に測定していない。   However, the prior art does not specifically measure the water content in a sulfide-based solid electrolyte that has not been oxidized.

特開2004−273451号公報JP 2004-273451 A 特開2010−108882号公報JP 2010-108882 A 特開2009−193727号公報JP 2009-193727 A 特開平03−002660号公報Japanese Patent Laid-Open No. 03-002660

そうしたことから硫化物系固体電解質中の水分量をより正確に測定することが求められていた。しかし、硫化水素を発生させない低温への加熱では水分が気化しきらず、硫化物系固体電解質の含有水分量を正確に測定することができなかった。   For this reason, it has been required to more accurately measure the amount of water in the sulfide-based solid electrolyte. However, heating to a low temperature that does not generate hydrogen sulfide does not completely vaporize, and the moisture content of the sulfide-based solid electrolyte cannot be measured accurately.

一方、硫化物系固体電解質を加熱すると、気化する水分の一部が硫化物系固体電解質と反応して硫化水素が発生する。そして水分と硫化水素との両方がカールフィッシャー試薬と反応してしまうことから、正確な水分量を検出することができないと考えられていた。   On the other hand, when the sulfide-based solid electrolyte is heated, a part of the vaporized water reacts with the sulfide-based solid electrolyte to generate hydrogen sulfide. Since both water and hydrogen sulfide react with the Karl Fischer reagent, it was thought that an accurate amount of water could not be detected.

そのため設備のコストが高く、測定時間も長いガス質量分析装置によって分析せざるを得なかった。   For this reason, it was unavoidable to analyze the gas mass spectrometer with a high equipment cost and a long measurement time.

本発明者らは、上記課題に鑑み鋭意努力した結果、1モルの水が硫化物系固体電解質と反応して1モルの硫化水素を生成すること、および硫化水素と水とがカールフィッシャー法においていずれも等モルのヨウ素(I)と反応することに着目し、従来法であるカールフィッシャー法を用いても、水分量を正確に測定できることを見いだし、本発明に至ったものである。 As a result of diligent efforts in view of the above problems, the inventors of the present invention have that 1 mol of water reacts with a sulfide-based solid electrolyte to produce 1 mol of hydrogen sulfide, and that hydrogen sulfide and water are in the Karl Fischer method. In all cases, focusing on the reaction with equimolar iodine (I 2 ), the inventors have found that the moisture content can be accurately measured even by using the Karl Fischer method, which is a conventional method, and have reached the present invention.

本発明の態様は、以下のようである。   Aspects of the present invention are as follows.

(1)硫化物系固体電解質を、その結晶化温度以上かつ分解温度以下の温度まで昇温しながら、
JIS K2275に準拠したカールフィッシャー法を用いる、硫化物系固体電解質中の水分量の測定方法。
(1) While raising the temperature of the sulfide-based solid electrolyte to a temperature above its crystallization temperature and below its decomposition temperature,
A method for measuring the amount of water in a sulfide-based solid electrolyte using the Karl Fischer method in accordance with JIS K2275.

本発明によれば、硫化物系固体電解質を高温まで加熱して硫化水素が発生したとしても、硫化物系固体電解質に含まれる正確な水分量の測定を行う方法の提供が可能となった。さらにカールフィッシャー法を用いることにより、ガス質量分析装置と比較して、簡便かつ低コストな測定方法の提供が可能となった。   ADVANTAGE OF THE INVENTION According to this invention, even if it heated the sulfide type solid electrolyte to high temperature and hydrogen sulfide generate | occur | produced, it became possible to provide the method of measuring the exact moisture content contained in a sulfide type solid electrolyte. Furthermore, by using the Karl Fischer method, it is possible to provide a simple and low-cost measurement method as compared with a gas mass spectrometer.

図1は、露点(−30℃)下において、固体電解質の粉末を暴露して水分を吸着させる様子を示す模式図である。FIG. 1 is a schematic diagram showing a state in which a solid electrolyte powder is exposed to adsorb moisture under a dew point (−30 ° C.). 図2は、加熱発生ガス質量(TPDーMS)分析装置を用いて各試料を測定した、(a)HO、(b)HSのそれぞれについてのガスの放出速度曲線を示す図である。FIG. 2 is a diagram showing gas release rate curves for (a) H 2 O and (b) H 2 S, in which each sample was measured using a heat generation gas mass (TPD-MS) analyzer. is there. 図3は、本発明の態様に係るカールフィッシャー法による固体電解質の、換算水分量の測定結果、および水分吸着量の算出結果を示すグラフである。FIG. 3 is a graph showing a measurement result of the converted water amount and a calculation result of the water adsorption amount of the solid electrolyte by the Karl Fischer method according to the embodiment of the present invention. 図4は、本発明の態様に係るカールフィッシャー法、および従来の加熱発生ガス質量分析法による測定結果について、固体電解質の質量変化に対する水分吸着量をプロットしたグラフである。FIG. 4 is a graph plotting the amount of moisture adsorbed with respect to the mass change of the solid electrolyte for the measurement results by the Karl Fischer method according to the embodiment of the present invention and the conventional heat generation gas mass spectrometry.

本明細書中において、各用語を以下のように規定する。
「硫化物系固体電解質」とは、Li、A、Sからなる式:Li−A−S(式中、Aは、P、Ge、B、Si、およびIからなる群より選ばれる少なくとも一種である。)で表される電解質をいう。
「結晶化温度」とは、ガラス状態を含む硫化物系固体電解質において、昇温により、ガラス状態を含む部分が結晶に変化する温度をいう。
「分解温度」とは、昇温により、硫化物系固体電解質が、水分との反応ではなく、分解反応により硫化水素を生成する温度をいう。
In this specification, each term is defined as follows.
The “sulfide-based solid electrolyte” is a formula consisting of Li, A, and S: Li—AS (where A is at least one selected from the group consisting of P, Ge, B, Si, and I). There is an electrolyte represented by.
“Crystallization temperature” refers to the temperature at which a portion containing a glass state changes to a crystal due to a temperature rise in a sulfide-based solid electrolyte containing a glass state.
The “decomposition temperature” refers to a temperature at which the sulfide-based solid electrolyte generates hydrogen sulfide by a decomposition reaction rather than a reaction with moisture by increasing the temperature.

本発明の態様では、水分と硫化水素との両者がカールフィッシャー試薬と等モルで反応していること、さらに硫化物系固体電解質中の水分との反応で生成した硫化水素および水分を放出させる温度に昇温することにより、硫化物系固体電解質中の水分量を測定できることに着目して測定を行うものである。   In the embodiment of the present invention, both water and hydrogen sulfide are reacted in equimolar amounts with the Karl Fischer reagent, and further, the hydrogen sulfide generated by the reaction with water in the sulfide-based solid electrolyte and the temperature at which water is released. The temperature is measured by paying attention to the fact that the water content in the sulfide-based solid electrolyte can be measured by raising the temperature.

詳しく説明すると、カールフィッシャー反応は、例えば電量滴定法の場合、次のように反応する。
1.まず回路に電流が通ぜられると白金陽極上でヨウ素(I)が生じる。
2I→I+2e (1)
More specifically, the Karl Fischer reaction reacts as follows in the case of coulometric titration, for example.
1. First, when current is passed through the circuit, iodine (I 2 ) is generated on the platinum anode.
2I → I 2 + 2e (1)

2.次にIによりSOが酸化されて、1モルの水分子(HO)当たり、1モル、すなわち、等モルのIが消費されて反応が進行する。
O+B・I+B・SO+ROH+B→2BH+BHROSO (2)
(式中、ROHは、メタノール、ジエチレングリコールモノメチルエーテルなどのアルコールであり、Bはイミダゾールなどの塩基である)
2. Next, SO 2 is oxidized by I 2 , and 1 mol, that is, equimolar I 2 is consumed per 1 mol of water molecule (H 2 O), and the reaction proceeds.
H 2 O + B · I 2 + B · SO 2 + ROH + B → 2BH + I + BH + ROSO 3 (2)
(In the formula, ROH is an alcohol such as methanol or diethylene glycol monomethyl ether, and B is a base such as imidazole)

3.ここで、測定される試料中に硫化水素などの妨害物質が存在すると、次のように反応してHO測定の妨害反応となる。
S+I→2S+HI (3)
3. Here, when an interfering substance such as hydrogen sulfide is present in the sample to be measured, it reacts as follows and becomes an interfering reaction of H 2 O measurement.
H 2 S + I 2 → 2S + HI (3)

4.しかし、式(3)に示すように、1モルのHS当たり、1モル、すなわち、等モルのIを消費して反応が進行する。
一方、硫化物系固体電解質を、結晶化温度以上かつ分解温度以下の温度に保てば、得られた硫化水素は、硫化物系固体電解質中の水分により発生したものであり、硫化物の分解により発生した硫化水素は含まれない。
4). However, as shown in Formula (3), the reaction proceeds by consuming 1 mole, that is, an equimolar amount of I 2 per mole of H 2 S.
On the other hand, if the sulfide-based solid electrolyte is kept at a temperature not lower than the crystallization temperature and not higher than the decomposition temperature, the obtained hydrogen sulfide is generated by moisture in the sulfide-based solid electrolyte, and the sulfide is decomposed. The hydrogen sulfide generated by is not included.

さらに結晶化温度以上かつ分解温度以下の温度に充分な期間保てば、非晶質構造中に取り込まれていた放出されにくい水を放出させて、測定することができる。   Furthermore, if the temperature is maintained at a temperature higher than the crystallization temperature and lower than the decomposition temperature for a sufficient period of time, it is possible to measure by releasing water that has been taken into the amorphous structure and is difficult to be released.

そうしたことから、結晶化温度以上かつ分解温度以下の温度まで昇温しながら、得られた硫化水素の量と水分との量を滴定することにより、硫化物系固体電解質中の水分量を測定できる。   Therefore, the amount of water in the sulfide-based solid electrolyte can be measured by titrating the amount of hydrogen sulfide and the amount of moisture obtained while raising the temperature to a temperature above the crystallization temperature and below the decomposition temperature. .

以上1〜4で説明したように、本発明の態様では、硫化物系固体電解質中の、水分との反応により生成した硫化水素および水分の両方を測定することにより、簡便かつ低コストなカールフィッシャー法によって、硫化物系固体電解質中の水分量を正確に測定している。   As described in 1 to 4 above, in the embodiment of the present invention, by measuring both hydrogen sulfide and moisture generated by the reaction with moisture in the sulfide-based solid electrolyte, a simple and low-cost Karl Fischer is obtained. The water content in the sulfide-based solid electrolyte is accurately measured by this method.

なお、上記の説明では、電量滴定法を例として説明したが、本発明の態様に係るカールフィッシャー法としては、JIS K2275に準拠しており、かつ問題を生じなければ、電量滴定法のほか、容量滴定法、水素化物反応法などを用いてもよい。   In the above description, the coulometric titration method has been described as an example. However, as the Karl Fischer method according to the aspect of the present invention, in addition to the coulometric titration method, in accordance with JIS K2275, if no problem occurs, A volumetric titration method, a hydride reaction method, or the like may be used.

さらに本発明の態様に係るカールフィッシャー法では、JIS K2275に記載の手順そのものでなくとも、JIS K2275に準拠している限り、全自動化されたカールフィッシャー式滴定装置を用いてもよい。   Furthermore, in the Karl Fischer method according to the embodiment of the present invention, a fully automated Karl Fischer titration apparatus may be used as long as it conforms to JIS K2275, not the procedure described in JIS K2275.

本発明の態様に係る硫化物系固体電解質は、上記で規定したようにLi−A−Sで表されるものを、特に制限なく使用できる。   As the sulfide-based solid electrolyte according to the embodiment of the present invention, those represented by Li—AS as defined above can be used without particular limitation.

Li−A−Sの例としては、例えば、Li10GeP12、Li3.25Ge0.250.75、30LiS−26B−44LiI、63LiS−36SiS−1Li、57LiS−38SiS−5LiSiO、70LiS−30P、50LiS−50GeS、Li11、Li3.250.95、LiGe0.250.75、80LiS−20P、LiS−SiS、LiI−P−LiS等を挙げることができる。 Examples of Li-A-S, for example, Li 10 GeP 2 S 12, Li 3.25 Ge 0.25 P 0.75 S 4, 30Li 2 S-26B 2 S 3 -44LiI, 63Li 2 S-36SiS 2 -1Li 3 P 2 O 4, 57Li 2 S-38SiS 2 -5Li 4 SiO 4, 70Li 2 S-30P 2 S 5, 50Li 2 S-50GeS 2, Li 7 P 3 S 11, Li 3.25 P 0 .95 S 4 , LiGe 0.25 P 0.75 S 4 , 80Li 2 S-20P 2 S 5 , Li 2 S—SiS 2 , Li 2 I—P 2 S 5 —Li 2 S, etc. .

本発明の態様で使用する硫化物系固体電解質としては、結晶化温度以上かつ分解温度以下の温度に昇温する過程において、水分および水分との反応で生成した硫化水素の放出を妨げなければ、バルク状、顆粒状、粉末状、ガラス状態、結晶状態などを含む硫化物系固体電解質を制限なく使用できる。   As the sulfide-based solid electrolyte used in the embodiment of the present invention, in the process of raising the temperature to a temperature not lower than the crystallization temperature and not higher than the decomposition temperature, it does not interfere with the release of moisture and hydrogen sulfide generated by the reaction with moisture, A sulfide-based solid electrolyte including a bulk shape, a granular shape, a powder shape, a glass state, a crystal state, and the like can be used without limitation.

結晶化温度および分解温度は、硫化物系固体電解質の組成によって変化し、例えば、加熱発生ガス分析法(TPD−MS:Temperature Programmed Desorption/Mass Spectrometry)などの分析法を用いて、個別に決定することができる。   The crystallization temperature and the decomposition temperature vary depending on the composition of the sulfide-based solid electrolyte, and are individually determined by using an analysis method such as a heat-generated gas analysis method (TPD-MS: Temperature Programmed Desorption / Mass Spectrometry). be able to.

そして結晶化温度以上かつ分解温度以下の温度は、結晶化温度以上かつ分解温度以下である限り、硫化物系固体電解質の組成、測定の都合などに応じて任意に設定できる。
さらに結晶化温度以上かつ分解温度以下の温度は、必要に応じて、結晶化温度以上かつ分解温度以下の範囲内の、(上昇、下降などを含め)任意の範囲で変動する温度、または一定の温度に設定できる。
The temperature not lower than the crystallization temperature and not higher than the decomposition temperature can be arbitrarily set depending on the composition of the sulfide-based solid electrolyte, the convenience of measurement, etc. as long as it is not lower than the crystallization temperature and not higher than the decomposition temperature.
Furthermore, the temperature above the crystallization temperature and below the decomposition temperature is a temperature that varies within an arbitrary range (including rising and falling) within a range above the crystallization temperature and below the decomposition temperature, as necessary. Can be set to temperature.

結晶化温度は、硫化物系固体電解質の組成によって異なるが、例えば、約240℃以上、約250℃以上、約260℃以上、約270℃以上、約280℃以上、約290℃以上、約300℃以上、約310℃以上、約320℃以上であることができる。   The crystallization temperature varies depending on the composition of the sulfide-based solid electrolyte. For example, the crystallization temperature is about 240 ° C. or higher, about 250 ° C. or higher, about 260 ° C. or higher, about 270 ° C. or higher, about 280 ° C. or higher, about 290 ° C. or higher, about 300 It can be at or above, at least about 310 ° C and at least about 320 ° C.

一方、分解温度は、硫化物系固体電解質の組成によって異なるが、例えば、約400℃以下、約390℃以下、約380℃以下、約370℃以下、約360℃以下、約350℃以下、約340℃以下であることができる。   On the other hand, although the decomposition temperature varies depending on the composition of the sulfide-based solid electrolyte, for example, about 400 ° C. or less, about 390 ° C. or less, about 380 ° C. or less, about 370 ° C. or less, about 360 ° C. or less, about 350 ° C. or less, about It can be 340 ° C. or lower.

本発明の態様では、典型的には、より低い温度、例えば室温において試料を測定装置中に入れた後、結晶化温度以上かつ分解温度以下の温度まで昇温しながら測定を行うが、結晶化温度以上かつ分解温度以下の温度までの昇温時間は、測定に問題を生じなければ、特に制限なく設定できる。   In the embodiment of the present invention, typically, after a sample is placed in a measuring device at a lower temperature, for example, room temperature, the measurement is performed while the temperature is raised to a temperature higher than the crystallization temperature and lower than the decomposition temperature. The temperature raising time to a temperature not lower than the temperature and not higher than the decomposition temperature can be set without any limitation as long as no problem occurs in the measurement.

必要に応じて、結晶化温度以上かつ分解温度以下の温度に昇温後、その温度に維持することができる。
この維持時間は、測定に問題を生じなければ、特に制限なく設定できる。
維持時間の下限は、硫化物系固体電解質の組成などによって異なるが、例えば、約5分以上、約10分以上、約20分以上、約30分以上、約40分以上であることができる。
一方、維持時間の上限は、硫化物系固体電解質の組成などによって異なるが、例えば、約80分以下、約70分以下、約60分以下、約50分以下であることができる。
また、維持時間を0としてもよい。
If necessary, the temperature can be raised to a temperature not lower than the crystallization temperature and not higher than the decomposition temperature, and then maintained at that temperature.
This maintenance time can be set without particular limitation as long as no problem occurs in the measurement.
The lower limit of the maintenance time varies depending on the composition of the sulfide-based solid electrolyte, and can be, for example, about 5 minutes or more, about 10 minutes or more, about 20 minutes or more, about 30 minutes or more, about 40 minutes or more.
On the other hand, the upper limit of the maintenance time varies depending on the composition of the sulfide-based solid electrolyte, and can be, for example, about 80 minutes or less, about 70 minutes or less, about 60 minutes or less, or about 50 minutes or less.
Further, the maintenance time may be zero.

下記に示すように、加熱発生ガス質量分析装置での測定では、吸着させた水分量にかかわらず、約280℃超の高温では、HOの放出は観察されなかった((参考測定1)、図2(a))。
これは、(参考測定1)で使用した硫化物系固体電解質が、約270℃〜約280℃において結晶化し、結晶化する過程において、非晶質構造中に取り込まれていた水が徐放される程度の放出速度となり、実質的にHOの放出速度が低下することによると思料される。
As shown below, in the measurement with the heat generation gas mass spectrometer, no release of H 2 O was observed at a high temperature exceeding about 280 ° C. regardless of the amount of adsorbed water ((Reference measurement 1) FIG. 2 (a)).
This is because the sulfide-based solid electrolyte used in (Reference Measurement 1) crystallizes at about 270 ° C. to about 280 ° C., and the water incorporated in the amorphous structure is gradually released during the crystallization process. It is thought that this is due to a decrease in the release rate of H 2 O substantially.

一方、吸着させた水分量にかかわらず、約80℃〜約350℃の範囲において、HSの放出が観察された((参考測定1)、図2(b))。
これは、(参考測定1)で使用した試料中に吸着された水分が硫化物系固体電解質と反応して、硫化水素を発生し、この硫化水素が放出されていることによると思料される。
On the other hand, H 2 S release was observed in the range of about 80 ° C. to about 350 ° C. regardless of the amount of adsorbed moisture ((Reference measurement 1), FIG. 2 (b)).
This is presumably because the water adsorbed in the sample used in (Reference Measurement 1) reacts with the sulfide-based solid electrolyte to generate hydrogen sulfide, and this hydrogen sulfide is released.

さらに昇温すると、約370℃以上の温度において、再度HSの放出速度が上昇している(図2(b))が、これは、硫化物系固体電解質の分解によるものと推定される。 When the temperature is further increased, the H 2 S release rate is increased again at a temperature of about 370 ° C. or more (FIG. 2B), which is presumed to be due to the decomposition of the sulfide-based solid electrolyte. .

下記に示されるように、本発明の態様では、結晶化温度以上かつ分解温度以下の間の温度として用いること、および硫化水素の等モル反応を利用することにより、加熱発生ガス質量(TPDーMS)分析と同等の測定精度で、硫化物系固体電解質中の水分の測定(図4など)を達成している。   As shown below, in the embodiment of the present invention, by using as a temperature between the crystallization temperature and the decomposition temperature or less and utilizing the equimolar reaction of hydrogen sulfide, the heat generation gas mass (TPD-MS ) Measurement of moisture in sulfide-based solid electrolytes (Fig. 4 etc.) has been achieved with the same measurement accuracy as analysis.

本発明が、実施形態により、制約されることを意図しないが、より理解の助けとするために、以下に、例示的に実施例などを記載する。   The present invention is not intended to be limited by the embodiments, but examples and the like will be described below for better understanding.

[測定装置]
(加熱発生ガス質量分析装置)
装置メーカー:(株)島津製作所、型番:GC/MS QP2010plus
[measuring device]
(Heat generation gas mass spectrometer)
Device manufacturer: Shimadzu Corporation, model number: GC / MS QP2010plus

(水分気化装置付きカールフィッシャー電量滴定装置)
水分気化装置メーカー:平沼産業(株)、型番:EV−2000
カールフィッシャー装置メーカー:平沼産業(株)、型番:AQ−300
(Karl Fischer coulometric titrator with moisture vaporizer)
Moisture vaporizer manufacturer: Hiranuma Sangyo Co., Ltd., model number: EV-2000
Karl Fischer equipment manufacturer: Hiranuma Sangyo Co., Ltd., model number: AQ-300

[試料の調製]
以下の手順により試料を調製した。
[Preparation of sample]
Samples were prepared by the following procedure.

(工程1):0.5gのLiS(メーカー名:高純度化学)と0.9gのP(メーカー名:アルドリッチ)とを0.5gのLiI(メーカー名:アルドリッチ)中において遊星ボールミルで反応させて、LiI−P−LiSを合成した。これを、粉末状に粉砕して4つに分割した。そして、このうちの1つを参照試料とした。 (Step 1): 0.5 g of Li 2 S (maker name: high-purity chemistry) and 0.9 g of P 2 S 5 (maker name: Aldrich) in 0.5 g of LiI (maker name: Aldrich) It is reacted in a planetary ball mill to synthesize a LiI-P 2 S 5 -Li 2 S. This was pulverized into powder and divided into four parts. One of them was used as a reference sample.

(工程2): (工程1)の試料3つについて、図2に示すように、大気圧下かつ露点温度−30℃において、それぞれ暴露時間を変化させて、電子天秤を用いて重量増加を測定しながら、0.3wt%,1.0wt%,3.0wt%水分を吸着させた3種類の試料を作製した。   (Step 2): As shown in FIG. 2, for three samples in (Step 1), the exposure time was changed at atmospheric pressure and at a dew point temperature of −30 ° C., and the weight increase was measured using an electronic balance. However, three types of samples with 0.3 wt%, 1.0 wt%, and 3.0 wt% moisture adsorbed were prepared.

なお、以下の例において、「換算水分量」とは、HOの量の測定値とHSの量の測定値との合計値をいう。
また、「水分吸着量」とは、各試料の換算水分量−参照試料の換算水分量をいう。
In the following examples, “equivalent water content” refers to the total value of the measured value of the amount of H 2 O and the measured value of the amount of H 2 S.
Further, the “moisture adsorption amount” refers to the equivalent moisture content of each sample minus the equivalent moisture content of the reference sample.

(参考測定1)
上記(工程1)、(工程2)により得た試料を使用して(加熱発生ガス質量分析装置)を用いて、
測定条件:He:50ml/分、昇温速度:10℃/分、測定温度範囲:室温(約25℃)〜500℃の条件下で、HOガスおよびHSガスについて、質量(M/Z値)=18で測定した。
(Reference measurement 1)
Using the sample obtained by the above (Step 1) and (Step 2) using a (heat generation gas mass spectrometer),
Measurement conditions: He: 50 ml / min, temperature increase rate: 10 ° C./min, measurement temperature range: room temperature (about 25 ° C.) to 500 ° C. With respect to H 2 O gas and H 2 S gas, mass (M / Z value) = 18.

Oについては、昇温するにつれて、水分吸着量の異なる3種の試料とも、それぞれ水分を放出した。約270℃では水分の放出速度が大きく低下し、約280℃超では水分の放出速度は確認されなかった(図2(a))。
一方、参照試料については、全測定範囲にわたってHOの放出速度はほとんど確認されなかった(図2(a):参照試料)。
Regarding H 2 O, as the temperature increased, water was released from each of the three types of samples having different moisture adsorption amounts. At about 270 ° C., the water release rate significantly decreased, and at about 280 ° C., the water release rate was not confirmed (FIG. 2 (a)).
On the other hand, for the reference sample, almost no release rate of H 2 O was observed over the entire measurement range (FIG. 2 (a): reference sample).

Sについては、水分吸着量の異なる3種の試料および参照試料において、3.0wt%など水分吸着量の多い試料程、幅広い範囲にわたってHSの放出速度が観察された。
特に、約80℃以上、結晶化温度(この試料の場合は約270℃)未満の温度においてすら、HSの正の放出速度が観察され、結晶化温度以上でなくても、HOが硫化物系電解質と反応していることが理解された(図2(b))。
With respect to H 2 S, among the three types of samples having different moisture adsorption amounts and the reference sample, the release rate of H 2 S was observed over a wider range as the sample had a higher moisture adsorption amount such as 3.0 wt%.
In particular, even at temperatures above about 80 ° C. and below the crystallization temperature (about 270 ° C. for this sample), a positive release rate of H 2 S is observed, and even if it is not above the crystallization temperature, H 2 O It was understood that has reacted with the sulfide-based electrolyte (FIG. 2 (b)).

4種の試料とも、約350℃〜約370℃にかけて、一旦HSの放出速度が低下したが、約370℃から再度HSの放出速度の増加が観察された。
参照試料においても約370℃からHSの放出速度が増加しているため、約370℃からの放出速度の増加は、試料の分解によるものと考えた。
In all four samples, the H 2 S release rate once decreased from about 350 ° C. to about 370 ° C., but an increase in the H 2 S release rate was observed again from about 370 ° C.
Since the H 2 S release rate increased from about 370 ° C. also in the reference sample, the increase in the release rate from about 370 ° C. was considered to be due to decomposition of the sample.

(実施例1)
上記(参考測定1)の結果から、結晶化温度以上かつ分解温度以下の温度を、HOおよびHSの放出速度が最低である、一定温度の350℃に設定した。
Example 1
From the result of the above (Reference measurement 1), the temperature not lower than the crystallization temperature and not higher than the decomposition temperature was set to a constant temperature of 350 ° C. at which the release rate of H 2 O and H 2 S was the lowest.

(工程2)において2種の試料について水分吸着量を、それぞれ0.9wt%および1.9wt%とした以外は(工程1)、(工程2)で得た試料を使用し、(水分気化装置付きカールフィッシャー電量滴定装置)を用いて、室温(約25℃)下で試料を測定装置中に入れた後、
測定条件:N:100ml/分、設定温度:350℃、測定時間:約60分の条件下で測定した。
The samples obtained in (Step 1) and (Step 2) were used except that the moisture adsorption amount was set to 0.9 wt% and 1.9 wt% for the two types of samples in (Step 2), respectively. Using a Karl Fischer coulometric titrator), the sample was placed in the measuring device at room temperature (about 25 ° C.),
Measurement conditions: N 2 : 100 ml / min, set temperature: 350 ° C., measurement time: about 60 minutes.

放出された換算水分の量は、測定時間で約30分まで増加した。
そして、約30分以降約60分までは緩やかな放出となり、水分を吸着させた各試料と、参照試料との傾きがほぼ同じになった(図3)。
The amount of converted moisture released increased up to about 30 minutes over the measurement time.
Then, from about 30 minutes to about 60 minutes, the release was gradual, and the inclination of each sample adsorbed with water and the reference sample became almost the same (FIG. 3).

そこで、測定時間40分の時点で測定した換算水分量に基づいて、水分吸着量を算出した。
結果は、0.9wt%、および1.9wt%水分を吸着させた試料、並びに参照試料において、それぞれ、18.6mg、8.7mg、2.8mgとなった(図3)。
Therefore, the moisture adsorption amount was calculated based on the converted moisture amount measured at the measurement time of 40 minutes.
The results were 18.6 mg, 8.7 mg, and 2.8 mg, respectively, in the sample in which 0.9 wt% and 1.9 wt% moisture were adsorbed, and the reference sample (FIG. 3).

(比較例1)
(参考測定1)の4種の試料について、(参考測定1)と同様の手順で測定し、3種の試料について換算水分量を算出した。
(Comparative Example 1)
The four samples of (Reference measurement 1) were measured in the same procedure as (Reference measurement 1), and the converted moisture content was calculated for the three samples.

(測定結果の検証)
上記(実施例1)の2種の試料、および(比較例1)の3種の試料、の測定結果に基づいて、固体電解質の質量変化に対して水分吸着量をプロットし、(実施例1)および(比較例1)の測定精度を比較した。結果を図4に示す。
(Verification of measurement results)
Based on the measurement results of the two types of samples in (Example 1) and the three types of samples in (Comparative Example 1), the water adsorption amount was plotted against the mass change of the solid electrolyte. ) And (Comparative Example 1) were compared in measurement accuracy. The results are shown in FIG.

その結果、(実施例1)および(比較例1)の試料について、水分吸着量/固体電解質の質量変化の傾きはほぼ一致し、本発明の態様が、簡便且つ低コストであるにも係わらず、加熱発生ガス質量分析と同等の測定精度を有することが確認された。   As a result, for the samples of (Example 1) and (Comparative Example 1), the moisture adsorption amount / the slope of the change in mass of the solid electrolyte are almost the same, and the aspect of the present invention is simple and low in cost. It was confirmed that the measurement accuracy was equal to that of the heat generation gas mass spectrometry.

上記のように本発明に係る水分量の測定方法によれば、硫化物系固体電解質の広範な組成にわたって、簡便かつ低コストで硫化物系固体電解質中の水分を測定できる。こうしたことから、本発明に係る方法は、制限なく様々な対象に利用することができる。   As described above, according to the method for measuring the amount of water according to the present invention, the moisture in the sulfide solid electrolyte can be measured easily and at low cost over a wide range of compositions of the sulfide solid electrolyte. Therefore, the method according to the present invention can be used for various objects without limitation.

Claims (1)

硫化物系固体電解質を、その結晶化温度以上かつ分解温度以下の温度まで昇温しながら、
JIS K2275に準拠したカールフィッシャー法を用いる、硫化物系固体電解質中の水分量の測定方法。
While raising the temperature of the sulfide-based solid electrolyte to a temperature above its crystallization temperature and below its decomposition temperature,
A method for measuring the amount of water in a sulfide-based solid electrolyte using the Karl Fischer method in accordance with JIS K2275.
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Cited By (1)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
CN116754349A (en) * 2023-08-16 2023-09-15 四川赛科检测技术有限公司 ICP-OES-based digestion method for lithium sulfide impurity elements and content determination method thereof

Cited By (2)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
CN116754349A (en) * 2023-08-16 2023-09-15 四川赛科检测技术有限公司 ICP-OES-based digestion method for lithium sulfide impurity elements and content determination method thereof
CN116754349B (en) * 2023-08-16 2023-11-21 四川赛科检测技术有限公司 ICP-OES-based digestion method for lithium sulfide impurity elements and content determination method thereof

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