JP2009054353A - Measuring method and measuring device of nonaqueous solution - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To measure with good precision hydrofluoric acid in non-aqueous solution containing a fluoride by a simple operation and with a simple device. <P>SOLUTION: The measuring method includes a process S102 in which a silicon-contained compound is added in a non-aqueous solution containing hydrofluoric acid, and the hydrofluoric acid and the silicon-contained compound are reacted, a process S112 to measure the quantity of a reaction compound which has reacted with hydrofluoric acid, and a process S114 to calculate the quantity of hydrofluoric acid in the non-aqueous solution based on the quantity of the reaction compound measured in the process S112. <P>COPYRIGHT: (C)2009,JPO&INPIT

Description

  The present invention relates to a measurement method and a measurement apparatus for a non-aqueous solution.

A lithium ion secondary battery is known as one of power sources for portable electronic devices and electric vehicles. In general, for lithium ion secondary batteries, for example, an electrolyte containing a fluorine-containing compound such as lithium hexafluorophosphate (LiPF ₆ ) or lithium tetrafluoroborate (LiBF ₄ ), EC (ethylene carbonate), PC A non-aqueous electrolyte solution dissolved in a suitable non-aqueous solvent such as (propylene carbonate) or DEC (diethyl carbonate) is used.

  When moisture enters a non-aqueous solution containing a fluorine-containing compound such as such a non-aqueous electrolyte solution, the fluorine-containing compound and water react to generate hydrofluoric acid (HF). Since hydrofluoric acid generally has the property of degrading electrodes and the like, such as corrosion of the current collector, the generation of HF in the electrolyte for lithium ion secondary batteries is a factor that has a significant effect on battery life. It is said to be one.

  Utilizing this property of the electrolyte for lithium ion secondary batteries, that is, by measuring the amount of hydrofluoric acid contained in the non-aqueous solution, for example, mixing water in the electrolyte for lithium ion secondary batteries It becomes possible to evaluate the degree of deterioration accompanying the use of the lithium ion secondary battery and whether it can be used for a lithium ion secondary battery.

  For example, Patent Document 1 describes an inspection method for determining the quality by quantifying the amount of fluorine generated by adding a specific radical to an electrolytic solution for a lithium ion battery and hydrolyzing it.

JP 2001-250587 A

  However, the inspection method described in Patent Document 1 may be suitable for simple inspection such as process management, but according to the inspection method, not only hydrofluoric acid but also It is difficult to accurately determine only the amount of hydrofluoric acid due to the influence of other fluorides different from hydrofluoric acid, such as lithium fluoride (LiF) produced by hydrolysis. There may be cases.

  The present invention provides a measuring method capable of measuring the amount of hydrofluoric acid contained in a non-aqueous solution with high accuracy, and a measuring apparatus to which this method can be applied.

  The configuration of the present invention is as follows.

  (1) adding a silicon-containing compound to a non-aqueous solution containing hydrofluoric acid to form a reaction product of the hydrofluoric acid and the silicon-containing compound; and the amount of the reaction product A method for measuring a non-aqueous solution, comprising: a step of measuring; and a step of calculating the amount of hydrofluoric acid in the non-aqueous solution based on the measured amount of the reaction product.

  (2) The measurement method according to (1), wherein the non-aqueous solution is an electrolyte for a lithium ion secondary battery.

  (3) The measurement method according to (1) or (2), wherein the silicon-containing compound is silicon dioxide or silica gel.

  (4) The measurement method according to any one of (1) to (3), wherein the step of measuring the amount of the reaction product includes a step of applying inductively coupled plasma emission spectroscopy. Method.

  (5) A silicon-containing compound addition means for adding a silicon-containing compound to a non-aqueous solution containing hydrofluoric acid, a reaction means for reacting the hydrofluoric acid and the silicon-containing compound, and the hydrogen fluoride A measuring device for measuring a non-aqueous solution, comprising: a measuring unit that measures the amount of a reaction product generated by a reaction between an acid and the silicon-containing compound.

  (6) The measurement apparatus according to (5), further including a calculation unit that calculates the amount of hydrofluoric acid in the non-aqueous solution based on the amount of the reaction product obtained by the measurement unit. measuring device.

  (7) The measuring apparatus according to (5) or (6), wherein the non-aqueous solution is an electrolyte for a lithium ion secondary battery.

  (8) The measuring apparatus according to any one of (5) to (7), wherein the silicon-containing compound is silicon dioxide or silica gel.

  (9) The measurement apparatus according to any one of (5) to (8), wherein the measurement unit includes an inductively coupled plasma emission spectrometer.

  According to the present invention, it is possible to accurately measure or quantify hydrofluoric acid contained in a non-aqueous solution.

  Hereinafter, embodiments of the present invention will be described with reference to the drawings. In addition, in each drawing, the same code | symbol is attached | subjected to the same structure and the description is abbreviate | omitted.

  FIG. 1 is a schematic diagram illustrating an example of the configuration of a non-aqueous solvent measurement apparatus according to an embodiment of the present invention.

  In FIG. 1, the measuring device 50 includes a reaction unit 12 having a silicon-containing compound addition unit 14, a reaction unit 16, and a measurement unit 20.

  In the reaction means 12, the silicon-containing compound addition unit 14 adds a silicon-containing compound to a predetermined amount of a non-aqueous solution (hereinafter also referred to as an electrolytic solution or a sample) 10 sent to the reaction unit 16. When a silicon-containing compound is added to the non-aqueous solution 10 containing hydrogen fluoride, a reaction product obtained by reacting hydrofluoric acid with the silicon-containing compound is obtained. At this time, it is preferable that the silicon-containing compound is excessively added to the hydrofluoric acid contained in the non-aqueous solution 10 to completely react the hydrofluoric acid contained in the non-aqueous solution 10.

  In this Embodiment, in order to improve the fluidity | liquidity of the added silicon-containing compound, it is also suitable to add and dilute a known amount of nonaqueous solvents as needed. As such a non-aqueous solvent, for example, anhydrous alcohols such as methanol, ethanol, propanol and the like are preferably used, but not limited thereto, for example, the same as the solvent used for the non-aqueous solution 10 which is a test sample. May be.

  In the present embodiment, in order to promote the reaction between hydrofluoric acid and the silicon-containing compound, a shaking mechanism, an ultrasonic generation mechanism, or the like may be provided in the reaction section 16 or in the vicinity thereof as necessary. good. When the reactivity between hydrofluoric acid and the silicon-containing compound is low, or when the fluidity of the silicon-containing compound is low, stirring is performed by applying a stirring mechanism such as a stirrer (rotor). Is also suitable.

  The reaction solution containing the reaction product obtained by reacting hydrofluoric acid contained in the non-aqueous solution 10 with the silicon-containing compound is treated in the solid content removing unit 18 as necessary, and is not reacted. The solid content containing the silicon-containing compound is removed. In the present embodiment, the solid content removing unit 18 may have any configuration as long as it can prevent the introduction of the solid content that becomes a foreign substance to the measurement unit 20 described later. The solid content removing unit 18 may be configured to remove insoluble components by, for example, filtration or adsorption, but may not necessarily be configured to completely separate solid and liquid, for example, sedimentation by standing. Also good. Further, for example, when the specific gravity of the silicon-containing compound to be added is sufficiently large with respect to the non-aqueous solution 10 and settles quickly, the solid content removing unit 18 can be omitted. Further, the solid content removing unit 18 may be permanently installed in the measuring device 50, or may be configured to be used only when desired as a separate body from the measuring device 50.

  In the embodiment of the present invention, hydrofluoric acid contained in the non-aqueous solution 10 reacts with the silicon-containing compound in the reaction means 12, and the resulting reaction product is not completely dissolved in the reaction solution. In the case where it cannot be separated from the solid phase, for example, adsorbed to a solid substance such as an excessively added silicon-containing compound, an error may occur in measurement by the measurement unit 20 described later. It is not preferable. In such a case, pretreatment, that is, treatment by the acid treatment means 24 is preferably performed before the treatment in the solid content removal unit 18 and / or the introduction into the measurement unit 20.

  In the present embodiment, the acid treatment means 24 includes an acid addition unit 26 and a reaction unit 28. The acid addition unit 26 adds an acid solution such as sulfuric acid to the reaction solution containing the solid matter containing the reaction composition sent to the reaction unit 28 to desorb the reaction product from the solid phase. If the reaction product reacted with hydrofluoric acid does not remain in the reaction solution and is adsorbed with an excessive amount of the silicon-containing compound, prior to the acid treatment by the acid treatment means 24. It is also preferable to filter off the solid material containing the reaction product of the silicon-containing compound and hydrofluoric acid by the filter separation unit 22. According to the present embodiment, not only can the reaction by the reaction unit 28 be made efficient, but also the amount of acid added by the acid addition unit 26 can be reduced, which is preferable.

  A reaction liquid obtained by adding a silicon-containing compound to the non-aqueous solution 10 and reacting with the hydrofluoric acid contained therein or an acid-treated liquid obtained by acid-treating the reaction liquid is measured by the measurement unit 20. The measurement unit 20 directly or indirectly measures the amount of the reaction product obtained by reacting with hydrofluoric acid dissolved in the reaction solution (acid treatment solution). Among the various fluorides contained in, only components derived from hydrofluoric acid can be selectively quantified. In addition, when a more accurate measurement of the amount of the reaction product derived from hydrofluoric acid contained in the non-aqueous solution 10 is desired, the mass of the non-aqueous solution 10 is accurately weighed, and then promptly Reaction and measurement are preferably performed. At this time, before introduction into the measuring unit 20, for example, an appropriate nonaqueous solvent (for example, anhydrous alcohol such as methanol, ethanol, propanol, etc.) is added to the obtained solution as necessary. The density may be adjusted by applying a treatment (meas up).

  As the measurement unit 20 shown in FIG. 1, for example, an inductively coupled plasma emission spectrometer (ICP-AES), an ICP mass spectrometer (ICP-MS), an ion chromatograph using an ion chromatography (IC) method, or the like is preferably used. However, ICP-AES is more preferable from the viewpoint of analysis sensitivity and measurement accuracy.

  The content of hydrofluoric acid can be calculated based on the amount of reaction product derived from hydrofluoric acid obtained by the measurement unit 20. At this time, it is also preferable to calculate the content of hydrofluoric acid in the non-aqueous solution 10 by the calculation unit 30 shown in FIG. In the present embodiment, a data processing unit (not shown) is provided, for example, in or near the calculation unit 30 shown in FIG. It is also preferable that the content of hydrofluoric acid in the non-aqueous solution 10 be automatically calculated. The content of hydrofluoric acid referred to here may be an absolute amount in the non-aqueous solution 10 subjected to measurement by the measuring device 50 or a content concentration in the non-aqueous solution 10. It is possible to set appropriately as required.

  The value of the content of hydrofluoric acid in the non-aqueous solution 10 obtained by the measuring device 50 can be used in various scenes as necessary, for example, for evaluating the deterioration state of the non-aqueous solution 10 or determining the suitability for use. Can be applied to.

  In this Embodiment, about the site | part exposed to the non-aqueous solution 10 and its reaction solution etc. at least in the measuring apparatus 50, for example, polyethylene (PE), polypropylene (PP), polytetrafluoroethylene (PTFE), etc. However, the resin material is not limited to this as long as the material is highly durable against each substance such as hydrofluoric acid.

  In the embodiment of the present invention, the measuring device 50 shown in FIG. 1 is provided with a valve 32 that can change the flow path of the reaction liquid according to the type of the silicon-containing compound added from the silicon-containing compound addition unit 14. In addition, as another embodiment, the filter separation unit 22 and the acid treatment means 24 may be configured to be detached from the measuring device 50 as necessary, and the mode is not limited.

  FIG. 2 is a flowchart illustrating an outline of a non-aqueous solution measurement method according to an embodiment of the present invention.

First, in step S100, a non-aqueous solution as a sample is weighed. The non-aqueous solution that can be suitably applied in the present embodiment is a non-aqueous solution containing or possibly containing hydrofluoric acid. For example, although it is not contained at the beginning of production, it may contain hydrofluoric acid produced by hydrolysis of a part of a fluorine-based electrolyte such as PF ₆ due to the mixing of moisture such as in the environment. Examples of the electrolytic solution for a lithium ion secondary battery include, but are not limited to, for example, an electrolytic solution for an electric double layer capacitor. The sample does not necessarily have to be prepared or stored as a solution. For example, a necessary amount of electrolyte solution can be collected from a filled lithium ion secondary battery and used as a sample. .

  In step S100, the sample used for one measurement is generally small, and can be appropriately set, for example, at about 1 to 10 g. However, the amount of components to be measured, the required measurement accuracy, and the sensitivity of the measurement instrument Thus, the scale-out amount can be set as appropriate. For example, when a non-aqueous solution containing about tens to several hundred ppm of hydrogen fluoride is used as a measurement sample, it is possible to use a sample of about 1 g for measurement. . The weighing in step S100 may be performed directly on the container (reaction vessel) for performing the operation of step S102 shown below, or the sample once weighed in an appropriate container may be transferred into the reaction vessel for performing the operation of S102. . When measuring the concentration, use a constant volume analyzer such as a whole pipette instead of weighing, measure a fixed volume such as 1 mL or 10 mL, and transfer it to the reaction vessel. Further, it may be a mode in which this is precisely weighed.

  Next, proceeding to step S102, the silicon-containing compound is added. In the present embodiment, the silicon-containing compound to be added is one that has high reactivity with hydrofluoric acid but does not easily react with other fluorides such as lithium fluoride. Suitable examples include silicon dioxide (also referred to as silica or silicic anhydride) and silica gel.

  In step S102, the silicon-containing compound added to the non-aqueous solution containing hydrofluoric acid selectively reacts with hydrofluoric acid to produce a reaction product. In order to react this reaction promptly and completely with hydrofluoric acid in the non-aqueous solution, an ultrasonic generation mechanism such as an ultrasonic cleaner, a shaker, a stirrer, etc. In order to prevent volatilization, it is also preferable to perform the treatment in a closed container provided with a lid or the like as necessary. In order to ensure that the hydrofluoric acid contained in the non-aqueous solution reacts with the silicon-containing compound, it is necessary to add the silicon-containing compound to at least an equivalent amount relative to the hydrofluoric acid contained. It is preferable to add an excessive amount of a silicon compound.

  In the present embodiment, even when a solid silicon-containing compound is added, it is preferable that the fluidity of the solution can be secured to some extent. For example, about 1 to 10 times the addition of the silicon-containing compound to the mass 1 of the sample However, the present invention is not limited to this. It is necessary to dilute the non-aqueous solution in advance because the concentration of hydrofluoric acid contained in the non-aqueous solution is high, or to ensure appropriate fluidity of the reaction solution after addition of the silicon-containing compound. Depending on the non-aqueous solution containing hydrofluoric acid, for example, an anhydrous alcohol or a non-aqueous solvent similar to the solvent used for the non-aqueous solution may be used as the diluent. Is preferred.

  In step S102, it is generally difficult to visually confirm the completion of the reaction. Therefore, for example, by performing a preliminary test in advance, a required reaction time is set in advance, and it can be considered that the reaction has ended when this time elapses. More specifically, the required reaction time can be about 10 to 60 minutes, more specifically about 30 minutes, but is not limited thereto.

  Next, the process proceeds to step S104, and the next process is determined. Here, different operations are performed according to the composition of the reaction product generated in step S102.

  In the present embodiment, when the reaction product obtained by the reaction between hydrofluoric acid and the silicon-containing compound is dissolved in the liquid phase of the reaction solution, the process proceeds to step S110. Examples of the silicon-containing compound that forms such a reaction product include silicon dioxide.

  On the other hand, if the reaction product obtained in step S102 does not dissolve in the liquid phase of the reaction liquid or does not dissolve at least completely in the liquid phase, the process proceeds to step S106. Examples of the silicon-containing compound that forms such a reaction product include silica gel.

  In step S106, a filtering process is performed as a pre-process of step S108. That is, when the reaction product contained in the reaction solution together with an excessive amount of the silicon-containing compound does not dissolve in the liquid phase and cannot be separated from solids such as the silicon-containing compound, the filtrate is removed by filtration. In step S106, any material that can be used as a normal filter material, such as filter paper or a membrane filter, may be used for the filtration process. However, it is necessary to have durability against all components that contain at least hydrofluoric acid and may be contained in the reaction solution, and the filter medium used is the silicon-containing compound used in step S102. However, those that do not leak into the filtrate are selected. If there is a possibility that a part of the reaction product is dissolved in the liquid phase, the step S106 is omitted, and the entire reaction liquid containing a solid substance such as a silicon-containing compound is subjected to the next step. Is also possible.

  In step S106, the residue after the solid layer is separated from the reaction solution, or the reaction solution from which step S106 is omitted is supplied to step S108. In step S108, acid treatment is performed, and a reaction product that cannot be easily separated from a solid substance such as a silicon-containing compound is dissolved in the liquid phase to be desorbed from the solid phase. For the acid treatment, for example, dilute sulfuric acid or dilute hydrochloric acid diluted to an appropriate concentration can be suitably used, but it is not limited thereto. Any acid may be used as long as the reaction product is desorbed from the solid phase and dissolved in the liquid phase, and the acid concentration is not particularly limited. For example, in the case of dilute sulfuric acid, It is also possible to prepare so that it may become about 10-50 mg / L.

  In step S108, the reaction product contained in the solid phase is eliminated by acid treatment or forms a liquid-phase-soluble silicon-fluorine compound and dissolves in the liquid phase in the treatment liquid.

  A reaction solution in which the reaction product generated by the addition of the silicon-containing compound (step S102) is dissolved in the liquid phase, or a liquid-phase-soluble silicon-fluorine compound obtained by the addition of the acid (step S108). The processing solution dissolved in the liquid phase is provided to step S110. In step S110, the solid content that is unnecessary for the measurement in step S112 and hinders the measurement is removed. The removal of the solid content in step S110 may be performed by a filter paper, a membrane filter, or the like that is generally used as a filter medium, or may simply be settled by leaving the container for a predetermined time, and there is no limitation on the method. Absent. In addition, a process performed by what is provided in an introduction part for introducing a reaction liquid / treatment liquid provided in step S112 described later may be included in step S110. If the solid content and the liquid phase in the reaction liquid / treatment liquid can be easily separated due to reasons such as a high sedimentation speed, and a subsequent process such as a constant volume treatment is unnecessary, step S110 is performed. Can be omitted.

  Here, the method for measuring the amount of hydrofluoric acid in the sample corresponding to Step S100 to Step S110 shown in FIG. 2 when silica gel is used as the silicon-containing compound will be illustrated more specifically. Needless to say, it is not limited to any form. In the present embodiment, unless otherwise specified, “part” and “%” are based on mass.

First, about 1 volume part of the sample is precisely weighed and placed in a suitable sealed container such as made of PE (corresponding to step S100 in FIG. 2). Next, 5 parts of silica gel (for example, silica gel (60) (silica gel for column chromatography (trade name), manufactured by Nacalai Tesque) can be used) and 20 parts by volume of ethanol (manufactured by Nacalai Tesque) are added. The lid is covered and stirred with a magnetic stirrer at room temperature for about 30 minutes (rotation speed: 300 rpm) to completely react hydrofluoric acid contained in the sample (corresponding to step S102). Here, Si in the silica gel reacts with hydrofluoric acid to produce a substance having a Si-F bond / SiF ₄ and H ₂ SiF ₆ are produced and adsorbed on the silica gel. It is considered that the silica gel and the reaction product coexist in at least one of the states.

  Here, after the solid content in the reaction liquid containing unreacted silica gel is allowed to settle for 10 minutes, it can be filtered using filter paper (5B) and dried at room temperature for 30 minutes (corresponding to step S106). .

A dilute sulfuric acid solution (for example, 96% sulfuric acid reagent (manufactured by Nacalai Tesque)) is added to the reaction solution in which the solid content has been precipitated or the solid content that has been dried after filtration and transferred to a PE reaction vessel again. 20 parts by volume) can be used, and the reaction product adsorbed on the solid content is stirred for 30 minutes using a magnetic stirrer (rotation speed: about 300 rpm). It can be desorbed (corresponding to step S108). Here, it is considered that the reaction compound that has reacted / adsorbed to the silica gel is desorbed, and silicon-fluorine compounds such as SiF ₄ and H ₂ SiF ₆ are dissolved in the solution.

  Next, as an operation corresponding to step S110, the silica gel can be allowed to settle by allowing to stand for several minutes (specifically, about 1 to 5 minutes). Moreover, when sedimentation is inadequate, it is also suitable to filter using a filter paper (5B) etc.

  As described above, the reaction liquid / treatment liquid that has finished Step S110 or omitted Step S110 is subjected to a measurement process (corresponding to Step S112).

  In step S112, by measuring the amount of the reaction product in the liquid phase of the reaction liquid or the amount of the silicon-fluorine compound dissolved in the liquid phase of the acid treatment liquid, various kinds of components contained in the non-aqueous solution 10 are measured. Of these fluorides, only compounds derived from hydrofluoric acid can be measured. In addition, when a more accurate measurement of the amount of hydrofluoric acid contained in the non-aqueous solution 10 is desired, after the mass of the non-aqueous solution 10 is precisely weighed, the reaction and measurement can be performed promptly. preferable. At this time, before introduction into the measurement unit 20, the concentration may be adjusted by, for example, performing a treatment (meas up) by adding an appropriate solvent to the obtained solution to obtain a constant volume. As the solvent used at this time, for example, anhydrous alcohols such as methanol, ethanol, propanol and the like can be suitably used, but in some cases, deionized water may be used.

  In step S112, for example, an ICP-AES, ICP-MS, an ion chromatograph to which an IC method is applied, or the like can be preferably used. In addition, when performing step S112, an appropriate reagent according to the measurement method to be applied, such as a standard solution for preparing a calibration curve, is prepared and prepared as necessary. Regardless of which of these apparatuses is applied, at least a portion that may come into contact with the reaction solution and / or the acid treatment solution, such as the introduction portion of the test sample, is S100 to S110 shown in FIG. Similar to each instrument such as a reaction vessel used in each step, durability to the test sample and hydrofluoric acid is required.

  Calculation of the content of hydrofluoric acid in the non-aqueous solution based on the measurement value of the reaction product / liquid phase-soluble silicon-fluorine compound derived from hydrofluoric acid obtained in step S112 Yes (corresponding to step S114). At this time, it is also preferable to use the measured value of the sample in step S100 as necessary. In step S114, the content of hydrofluoric acid in the non-aqueous solution is automatically calculated by the calculation unit provided in the measuring device used in step S112. It does not matter what is configured. The content of hydrofluoric acid here may be an absolute amount or a concentration of the non-aqueous solution 10 and can be appropriately set according to a required value. .

  Thus, according to the measurement method shown in step S100 to step S114 in FIG. 2, even when a plurality of fluorides are contained in a non-aqueous solution such as an electrolytic solution, it is selectively selected from only hydrofluoric acid. Hydrofluoric acid contained in a non-aqueous solution by adding / reacting a silicon-containing compound that reacts with and measuring the amount of the reaction product obtained directly or indirectly as a soluble silicon-fluorine compound It is possible to accurately measure the amount of.

<Samples and reagents>
The samples and reagents used in the examples are shown below. Unless otherwise specified, both “parts” and “%” are based on mass, and the environmental conditions in each treatment step are room temperature 24-26 ° C. and relative humidity 50-60%.

As a measurement sample, an electrolytic solution for a lithium ion secondary battery in which lithium hexafluorophosphate (LiPF ₆ ) is dissolved in an electrolytic solution mainly composed of ethylene carbonate so as to have a concentration of 1 mol / L is obtained under various conditions. And stored. The storage conditions of the used measurement samples (Samples 1 to 4) are summarized in Table 1.

As one of the silicon-containing compounds, silicon dioxide (high purity compound SiO ₂ (trade name), manufactured by Rare Metallic, purity 99.99%) was used.

[Example 1]
According to the method shown in FIG. 2, each measurement sample shown in Table 1 was processed, and the hydrofluoric acid content in each sample was quantified.

About 1 volume part of the sample was precisely weighed and placed in a prepared polyethylene container (corresponding to step S100 in FIG. 2). Next, 0.01 part of silicon dioxide was added, and ultrasonic vibration was applied for about 30 minutes at room temperature using an ultrasonic cleaner to completely react hydrofluoric acid contained in the sample (same as above). Equivalent to step S102). Here, it is considered that silicon dioxide and hydrofluoric acid react with each other in the electrolytic solution to produce SiF ₄ and H ₂ SiF ₆ .

  Next, as an operation corresponding to Step S110, the silicon dioxide was allowed to settle by allowing it to stand for several minutes (specifically, about 2 to 5 minutes).

  Next, as an operation corresponding to step S112, the amount of silicon dissolved in the reaction solution was analyzed using an ICP emission spectroscopic analyzer (ICP-S8100, manufactured by Shimadzu Corporation). The measurement conditions and the calibration curve solution preparation method are as follows.

<Measurement conditions>
High frequency output: 1.6 kW
Observation height: 15cm
Integration time: 15 seconds x 3
Argon gas amount: For cooling 16 L / min, auxiliary 1.5 L / min, carrier 0.7 L / min Quantitative method: calibration curve method Analytical wavelength: 251.61 nm (Si).

<Preparation of calibration curve solution>
Commercially available 0.1 mol / L hydrofluoric acid (manufactured by Nacalai Tesque) was weighed out in a predetermined amount (0 to 0.5 mL in this case) so that the concentration was stepwise, and an excess amount of silicon dioxide (0 .01 parts) was added, and the same operation as in Example 1 was performed to obtain a calibration curve solution.

  FIG. 3 shows the relationship between the hydrofluoric acid concentration (unit: ppm) obtained based on the measurement result of the calibration curve solution by the ICP emission spectroscopic analyzer and the emission intensity by ICP measurement. As shown in FIG. 3, the correlation coefficient R of the obtained calibration curve was 0.9991, and a result having good linearity was obtained.

  The same operation was performed twice for each sample shown in Table 1, and the content of hydrofluoric acid in each sample was calculated. The results are shown in Table 2.

  According to Table 2, there was almost no error between the two measured values for each sample, and good measurement results were obtained.

  The present invention is not limited to electrolytes for lithium ion secondary batteries, and can be used for measurement of non-aqueous solutions containing hydrofluoric acid.

It is a figure which shows the outline of a structure of the measuring apparatus of the non-aqueous solution in embodiment of this invention. It is a flowchart which illustrates the measuring method of the non-aqueous solution in embodiment of this invention. It is an example of the graph which shows the calibration curve showing the relationship between the hydrofluoric acid density | concentration and the emitted light intensity by ICP-AES.

Explanation of symbols

  10 non-aqueous solution, 12 reaction means, 14 silicon-containing compound addition part, 16 reaction part, 18 solid content removal part, 20 measurement part, 22 filtration part, 24 acid treatment means, 26 acid addition part, 28 reaction part, 30 Calculation unit, 32 valves, 50 measuring device.

Claims (9)

Adding a silicon-containing compound to a non-aqueous solution containing hydrofluoric acid to form a reaction product of the hydrofluoric acid and the silicon-containing compound;
Measuring the amount of the reaction product;
Calculating the amount of hydrofluoric acid in the non-aqueous solution based on the measured amount of the reaction product;
A method for measuring a non-aqueous solution, comprising: The measurement method according to claim 1,
The measurement method, wherein the non-aqueous solution is an electrolytic solution for a lithium ion secondary battery. The measurement method according to claim 1 or 2,
The measuring method, wherein the silicon-containing compound is silicon dioxide or silica gel. In the measuring method of any one of Claim 1 to 3,
The method for measuring the amount of the reaction product includes a step of applying inductively coupled plasma emission spectrometry. A silicon-containing compound addition means for adding a silicon-containing compound to a non-aqueous solution containing hydrofluoric acid,
A reaction means for reacting the hydrofluoric acid and the silicon-containing compound;
Measuring means for measuring the amount of the reaction product produced by the reaction of the hydrofluoric acid and the silicon-containing compound;
An apparatus for measuring a non-aqueous solution, comprising: The measuring apparatus according to claim 5, wherein
The measuring apparatus further comprising a calculating means for calculating the amount of hydrofluoric acid in the non-aqueous solution based on the amount of the reaction product obtained by the measuring means. The measuring apparatus according to claim 5 or 6,
The non-aqueous solution is an electrolytic solution for a lithium ion secondary battery. In the measuring device according to any one of claims 5 to 7,
The measuring apparatus, wherein the silicon-containing compound is silicon dioxide or silica gel. In the measuring device according to any one of claims 5 to 8,
The measuring device includes an inductively coupled plasma emission spectrometer.

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