System and method for testing concentration of chromium dichloride in electrolyte and application

Abstract

The invention relates to the technical field of energy storage and flow batteries, in particular to an electrolyte chromium dichloride concentration testing system and method and application. The system comprises an inert atmosphere device and a testing device, and the testing device is arranged in the inert atmosphere device; a potential monitor and a titration sub-device are arranged in the testing device. According to the method, the ferric chloride solution with a certain concentration is used as the oxidizing agent, the oxidation-reduction potentiometric titration test is carried out in the inert gas atmosphere, the oxidizing agent is not prone to deterioration, economical and easy to obtain and does not react with any other substances / ions except Cr < 2 + > in the electrolyte, the test accuracy is guaranteed, and the test time is shortened. The method for judging the reaction endpoint by potential mutation avoids the interference of ion color judgment, so that the accurate concentration of Cr < 2 + > in the electrolyte of the iron-chromium flow battery can be quickly obtained.

Description

Technical Field

[0001] The invention relates to the technical field of energy storage and liquid flow batteries, and in particular to a system and method for testing the concentration of chromium dichloride in an electrolyte, and applications thereof. Background Art

[0002] As an important energy storage device, iron-chromium flow battery has broad application prospects in renewable energy storage, smart grid and large-scale energy storage systems due to its long life, high energy density, fast charge and discharge and environmental friendliness. 2+ However, this technology achieves the storage and release of electrical energy through the conversion of the valence state of iron ions and chromium ions in the electrolyte. Therefore, during the charging and discharging process, the electrolyte of the iron-chromium flow battery usually contains ions of various elements and valence states, mainly iron ions (Fe 2+ / Fe 3+ ), chromium ion (Cr 3+ / Cr 2+ ), hydrogen ion (H + ), chloride ion (Cl - ) and other trace ions such as phosphate ions (PO4 3- ) and calcium ions (Ca 2+ ), magnesium ion (Mg 2+ ), manganese ion (Mn 2+ ) and zinc ions (Zn 2+ ) etc., among which divalent chromium ion (Cr 2+ ) As the active material of the negative electrode, it plays a vital role in the battery charging and discharging process.

[0003] NB / T 11067-2023 Technical Specification for Electrolyte for Iron-Chromium Flow Batteries specifies the test methods for the concentration of various ions involved in the electrolyte of iron-chromium flow batteries, including divalent iron ions, trivalent iron ions, trivalent chromium ions and hydrogen ions. However, an uncommon ion Cr generated during the charge and discharge operation 2+ Currently, there is no method to detect this ion, which brings inconvenience to monitoring the operating status of flow batteries and subsequent product design.

[0004] The existing test method for the concentration of chromium dichloride in the electrolyte of iron-chromium flow battery is missing because Cr 2+ There are many challenges in concentration testing. First, this is mainly limited by Cr 2+ The reducing property is very strong. Secondly, the electrolyte usually contains a variety of ions, such as iron ions, chromium ions and free acids. The mutual interference between these ions makes it difficult to directly determine Cr 2+ If the common potassium dichromate redox titration method is used, the divalent iron ions in the electrolyte will not participate in the reaction and Cr2+ concentration; if Cr 2+ Determination of the concentration of Cr 2+ During the lengthy solution pretreatment process, it will be oxidized to trivalent chromium ions, so only the total chromium ion concentration can be obtained, and the concentration of chromium ions of different valence states cannot be distinguished. Since this ion concentration has a key impact on the development and promotion of iron-chromium flow battery technology, it is necessary to develop an accurate and reliable Cr 2+ The concentration test method is an urgent problem to be solved.

[0005] In summary, the Cr in the electrolyte of iron-chromium flow battery 2+ Due to the shortcomings of the existing technology of concentration testing, it is necessary to develop a testing method that is simple to operate, accurate and reliable, and suitable for complex electrolyte systems to meet the testing needs of iron-chromium flow batteries in practical applications. It can also be used to accurately estimate the SOC of iron-chromium flow battery systems, which is of great significance for evaluating battery performance, optimizing battery management strategies, and ensuring the stable operation of battery systems. Summary of the invention

[0006] In order to solve the above problems, the present invention provides a system and method for testing the concentration of chromium dichloride in an electrolyte, and an application thereof. The present invention provides the following technical solutions:

[0007] In a first aspect of the present invention, a system for testing the concentration of chromium dichloride in an electrolyte is provided, the system comprising an inert atmosphere device and a testing device, wherein:

[0008] The testing device is arranged inside the inert atmosphere device;

[0009] The testing device is provided with a potential monitor and a titration sub-device inside;

[0010] The inert atmosphere device comprises: a box, a first pipeline, a second pipeline, rubber gloves, a transfer port and an oxygen detector, wherein:

[0011] A first hole is provided on the first side of the box body; one end of the first pipe is connected to the box body through the first hole;

[0012] The second side of the box body is provided with a transmission port and a second hole; one end of the second pipe is connected to the second side of the matching box body through the second hole;

[0013] A rubber glove is arranged on the third side of the box body, and the rubber glove is sealed and connected to the box body through a sealing ring;

[0014] An oxygen detector is arranged on the top of the box.

[0015] Specifically, the inert atmosphere device also includes: a stop valve, a sealing ring and an inert gas cylinder, wherein:

[0016] The first hole and the second hole are both provided with sealing rings;

[0017] The other end of the first pipeline is connected to the outside world; a stop valve is arranged on the other end of the first pipeline connected to the outside world;

[0018] An inert gas cylinder is connected to the other end of the second pipeline.

[0019] Specifically, a first pressure reducing valve is provided at the outlet of the inert gas cylinder, and the other end of the second pipeline is connected to the inert gas cylinder through the first pressure reducing valve.

[0020] Specifically, a second pressure reducing valve is provided on the second pipeline, and the second pressure reducing valve is located between the box body and the first pressure reducing valve.

[0021] Specifically, the titration sub-device includes a main unit, a sealed bottle, a burette, a stirrer and a test bottle, wherein:

[0022] The sealed bottle is used to hold the titrant, and the test bottle is used to hold the liquid to be tested;

[0023] The sealed bottle is connected to the burette inlet through a first pipeline, and the burette outlet is connected to the test bottle through a second pipeline;

[0024] The host is internally integrated with a burette driver, which is connected to the burette and is used to push the titrant in the sealed bottle along the pipeline through the burette into the test bottle;

[0025] The stirrer and the potential detector are both arranged inside the test bottle.

[0026] Specifically, the testing device further includes a fixture,

[0027] The fixture is used to fix the stirrer and the potential detector; or,

[0028] The holder is used to fix the potential detector.

[0029] Specifically, the potential detector includes an indicator electrode and a reference electrode;

[0030] The host is connected to the indicator electrode and the reference electrode, and is used to detect the potential change caused by the redox reaction process of the titrant and the liquid to be tested.

[0031] In a second aspect of the present invention, a method for testing the concentration of chromium dichloride in an electrolyte is provided, using the system as described above, the method comprising:

[0032] The inert atmosphere device is filled with inert gas;

[0033] The titrant and the test liquid are placed in a sealed bottle and a test bottle respectively; wherein the potential monitor penetrates into the test liquid;

[0034] The test device is turned on, and the stirrer stirs the test liquid at a predetermined stirring speed. The titrant in the sealed bottle is pumped into the burette along the first pipeline, and the titrant in the burette is pushed into the test bottle along the second pipeline at a predetermined titration speed to undergo a redox reaction with the test liquid.

[0035] When the potential monitor detects the potential change of the test solution after the redox reaction occurs, the titration is stopped and the amount of titrant used at this time is recorded.

[0036] Specifically, the process of filling the inert gas into the inert atmosphere device includes:

[0037] The oxygen detector monitors the gas composition in the box online. When the oxygen concentration reaches 20ppm or above, open the first valve to 0.3-0.6MPa, the second valve to 0.3-0.6Mpa, open the stop valve, and purge the box until the oxygen concentration reaches 20ppm or below and maintains for a predetermined time, and adjust the second pressure reducing valve 10 to 0.15-0.3Mpa.

[0038] Specifically, the method further includes obtaining the liquid to be tested, including the following steps:

[0039] The electrolyte to be tested containing chromium dichloride is diluted 100 to 300 times to obtain a solution to be tested.

[0040] Specifically, the titrant is ferric chloride solution, and the concentration of the ferric chloride solution is 0.05-0.2 mol / L.

[0041] Specifically, the calculation formula for the concentration of chromium dichloride ions in the electrolyte to be tested is as follows:

[0042] C1=C0*V2 / V1

[0043] Wherein, C1 represents the concentration of chromium dichloride in the electrolyte to be tested, C0 represents the concentration of ferric chloride in the titrant, V2 represents the volume of the titrant participating in the redox reaction, and V1 represents the total volume of the test solution after dilution.

[0044] In a third aspect of the present invention, the system described above is provided for testing Cr in an electrolyte of an iron-chromium flow battery. 2+ Application of concentration.

[0045] Technical effects and advantages of the present invention:

[0046] The present invention proposes to use a certain concentration of ferric chloride solution as an oxidant to perform a redox potential titration test in an inert gas atmosphere. The oxidant is not easy to deteriorate, is economical and easy to obtain, and will not react with Cr in the electrolyte. 2+The method of using potential mutation to determine the reaction end point avoids the interference of ion color determination, thus quickly obtaining the Cr in the electrolyte of the iron-chromium flow battery. 2+ The exact concentration.

[0047] This method will not be affected by the various ion colors in the electrolyte, nor will it introduce other characteristic redox substances / ions that may reduce the test accuracy. The test accuracy can reach 10 -5 ~0.01mol / L (the test accuracy can be adjusted according to the device), with the characteristics of accurate testing, high reliability and simple operation.

[0048] Other features and advantages of the present invention will be described in the following description, and partly become obvious from the description, or be understood by implementing the present invention. The purpose and other advantages of the present invention can be realized and obtained by the structures pointed out in the description and the drawings. BRIEF DESCRIPTION OF THE DRAWINGS

[0049] Figure 1 is a structural diagram of an inert atmosphere device provided in an embodiment of the present application;

[0050] Figure 2 is a structural diagram of a test device provided in an embodiment of the present application;

[0051] Figure 3 is a potential monitoring structure diagram provided in an embodiment of the present application;

[0052] Figure 4 It is the change process of potential and potential change rate during the titration test of sample 1 provided in the embodiment of the present application;

[0053] Figure 5 This is the process of changing the potential and the rate of potential change during the titration test of Sample 2 provided in the embodiment of the present application.

[0054] In the figure: 1-box; 2-stop valve; 3-sealing ring; 4-rubber gloves; 5-transmission port; 6-oxygen detector; 7-sealing ring; 8-inert gas bottle; 9-first pressure reducing valve; 10-second pressure reducing valve; 11-test device; 11-1-host; 11-2-sealed bottle; 11-3-burette; 11-4-bracket and holder; 11-5-stirring paddle; 11-6-test bottle; 11-7-potential monitor; 11-7-1-indicator electrode; 11-7-2-reference electrode. DETAILED DESCRIPTION

[0055] The following will be combined with the drawings in the embodiments of the present invention to clearly and completely describe the technical solutions in the embodiments of the present invention. Obviously, the described embodiments are only part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of the present invention.

[0056] In order to solve the deficiencies of the prior art, the present invention discloses a system for testing the concentration of chromium dichloride in an electrolyte, such as Figure 1 As shown, the system includes an inert atmosphere device and a testing device, wherein the testing device is arranged inside the inert atmosphere device; a potential monitor and a titration sub-device are arranged inside the testing device.

[0057] Combination Figure 1 The inert atmosphere device comprises: a box body 1, a stop valve 2, a sealing ring 3, a rubber glove 4, a transmission port 5, an oxygen detector 6, a sealing ring 7 and an inert gas cylinder 8, wherein a first hole matching with a first pipe is arranged on a first side of the box body 1; one end of the first pipe is connected to the box body 1 through a sealing ring, the other end of the first pipe is connected to the outside, and a stop valve 2 is arranged on the other end of the first pipe connected to the outside; a transmission port 5 and a second hole matching with a second pipe are arranged on a second side of the box body 1; one end of the second pipe is connected to the box body 1 through a sealing ring 3, and the other end of the second pipe is connected to the inert gas cylinder 8; a rubber glove 4 is arranged on a third side of the box body 1, and the rubber glove 4 is sealed and connected to the box body 1 through a sealing ring 7; an oxygen detector 6 is arranged on the top of the box body 1.

[0058] A first pressure reducing valve 9 is provided at the outlet of the inert gas cylinder 8, and the other end of the second pipeline is connected to the inert gas cylinder 8 through the first pressure reducing valve 9. A second pressure reducing valve 10 is provided on the second pipeline, and the second pressure reducing valve 10 is located between the box 1 and the first pressure reducing valve 9.

[0059] In a specific embodiment of the present invention, the box 1 is a box containing a cavity inside, and the box 1 is connected to the outside through a stop valve 2, and its function is to provide an inert atmosphere environment for the redox titration test; the size of the cavity inside the box 1 should be able to meet the space requirements of the equipment, devices, components, drugs and other auxiliary items required for the redox titration test and the test process;

[0060] In a specific embodiment of the present invention, the device comprises a transfer port 5, which is a sealed port with a sealing strip and a hydraulic rod device; it can realize the transfer of equipment, devices, components, drugs and other auxiliary items required for the redox titration test and the test process.

[0061] In a specific embodiment of the present invention, the oxygen detector 6 can realize online monitoring of the gas composition in the box 1. When the oxygen concentration reaches 20ppm or above, it is necessary to open the first valve 9 to 0.3~0.6MPa and the second valve 10 to 0.3~0.6MPa, and the stop valve 2 to purge the box. When the oxygen concentration is maintained at 20ppm or below for 10min, the second pressure reducing valve 10 can be adjusted to 0.15~0.3Mpa for test operation.

[0062] Combination Figure 2 The titration sub-device includes a host 11-1, a sealed bottle 11-2, a burette 11-3, a stirrer and a test bottle 11-6, wherein:

[0063] The sealed bottle 11-2 is used to hold a titrant, preferably a solution containing 0.05-0.2 mol / L of ferric chloride;

[0064] The test bottle 11-6 is used to hold the test liquid, which is an electrolyte diluted 100 to 300 times;

[0065] 1. The sealed bottle 11-2 is connected to the inlet of the burette 11-3 through a first pipeline, and the outlet of the burette 11-3 is connected to the test bottle 11-6 through a second pipeline; the host is internally integrated with a burette driver, and the burette driver is connected to the burette 11-3, and is used to push the titrant in the sealed bottle 11-2 along the pipeline through the burette 11-3 to the test bottle 11-6 to undergo an oxidation-reduction reaction with the test liquid; the potential detector is inserted into the test liquid to detect the potential change caused by the oxidation-reduction reaction process of the titrant and the test liquid.

[0066] The stirrer and the potential detector 11 - 7 are both arranged inside the test bottle.

[0067] In a specific embodiment of the present invention, the agitator can be a stirring paddle 11-5 to enable a device capable of achieving speed-adjustable stirring, and can also be replaced by a component capable of achieving magnetic stirring, the purpose of which is to make the solution have a uniform concentration during the reaction process and to make the measurement result more accurate; the stirring speed of the agitator is 200r / min-500r / min.

[0068] In a specific embodiment of the present invention, the testing device also includes a fixture. When the agitator can be a stirring paddle 11-5, the fixture is used to fix the stirring paddle 11-5 and the potential detector 11-7; or, when the agitator can be a magnetic stirrer, the fixture is used to fix the potential detector 11-7.

[0069] In a specific embodiment of the present invention, Figure 3 As shown, the potential detector 11-7 includes an indicator electrode 11-7-1 and a reference electrode 11-7-2;

[0070] The host 11-1 is connected to the indicator electrode 11-7-1 and the reference electrode 11-7-2, and is used to detect the potential change caused by the redox reaction process of the titrant and the test liquid.

[0071] In a specific embodiment of the present invention, the host 11-1 is a device capable of providing a regulated power supply and realizing real-time voltage and current testing; the potential change detection and endpoint judgment of the above reaction process use a potential monitor 11-7, and the system can detect the potential change caused by the redox reaction process of the titrant and the test liquid. It should be noted that the potential change caused by the redox reaction process of the titrant and the test liquid will have different potentials and potential change standards for different electrodes, as long as the redox potential jump can be achieved, and the potential jump range is 300 to 900 mV / ml.

[0072] The present invention also provides a method for testing the concentration of chromium dichloride in an electrolyte, using the system as described above, the method comprising:

[0073] The electrolyte to be tested containing chromium dichloride is diluted 100 to 300 times to obtain a solution to be tested.

[0074] Prepare a titrant, which is a solution with a ferric chloride concentration of 0.05 to 0.2 mol / L. The choice of ferric chloride concentration in the titrant is to first determine the amount of the titrant based on the accuracy requirement. For example, when the error is within 1%, 1% is one drop of error. At this time, V2 requires at least 100 drops to meet the accuracy requirement (1 ml is equivalent to 20-25 drops). If the titration efficiency is considered at the same time, V2 can be set between 100 and 200 drops. This method is used to set the liquid output rate according to the volume of the test liquid and the estimated concentration to reduce the error of the titration test. The titrant and the test liquid are placed in a sealed bottle and a test bottle respectively; wherein the potential monitor penetrates into the interior of the test liquid;

[0075] The inert atmosphere device is filled with inert gas, and the oxygen detector 6 monitors the gas composition in the box 1 online. When the oxygen concentration reaches 20ppm or above, the first valve 9 is opened to 0.3-0.6MPa, the second valve 10 is opened to 0.3-0.6Mpa, and the valve 2 is opened to purge the box;

[0076] The test device is turned on, and the stirrer stirs the test liquid at a predetermined stirring speed. The titrant in the sealed bottle is pumped into the burette along the first pipeline, and the titrant in the burette is pushed into the test bottle along the second pipeline at a predetermined titration speed to react with the test liquid in a redox reaction; the predetermined titrant speed is 10μl / s to 50μl / s. When the potential monitor detects a change in the potential of the test liquid after the redox reaction, the titration is stopped and the amount of titrant used (volume) is recorded.

[0077] The calculation formula for the concentration of chromium dichloride in the electrolyte to be tested is as follows:

[0078] C1=C0*V2 / V1

[0079] Wherein, C1 represents the concentration of chromium dichloride in the electrolyte to be tested, C0 represents the concentration of ferric chloride in the titrant, V2 represents the volume of the titrant participating in the redox reaction, and V1 represents the total volume of the test solution after dilution.

[0080] The present invention also provides a method for testing Cr in an electrolyte of an iron-chromium liquid flow battery using the system of the present invention. 2+ Application of concentration.

[0081] The technical solution of the present invention will be further described below in conjunction with specific implementation methods.

[0082] S1. Take 10-100 ml of electrolyte in any charge and discharge state and place it in an inert atmosphere system for standby use;

[0083] Table 1: Changes in main components and ion types during use of iron-chromium electrolyte

[0084]

[0085] According to Table 1, before charging, the positive electrode ions in the electrolyte mainly include ferrous chloride, ferric chloride, chromium trichloride and hydrochloric acid, and the negative electrode ions mainly include ferrous chloride, ferric chloride, chromium trichloride and hydrochloric acid. There is a small amount of ferric chloride in the electrolyte before charging. After charging, the positive electrode ions mainly include ferrous chloride, ferric chloride, chromium trichloride and hydrochloric acid; the negative electrode ions mainly include ferrous chloride, chromium trichloride, chromium dichloride and hydrochloric acid.

[0086] S2. The electrolyte contains a certain concentration of iron ions (divalent / trivalent), chromium ions (divalent / trivalent), hydrogen ions, chloride ions, phosphate ions, calcium ions, magnesium ions, manganese ions and zinc ions, wherein the iron ion concentration is 0.5-2 mol / L, the chromium ion concentration is 0.5-2 mol / L, the hydrogen ion concentration is 0.5-5 mol / L, the chloride ion concentration is 3-15 mol / L, and the phosphate ion, calcium ion, magnesium ion, manganese ion and zinc ion concentration are 0.1-5 mmol / L;

[0087] Table 1 lists the types of ions in the electrolyte during the charge and discharge process of the iron-chromium flow battery. Therefore, when selecting a titrant for the chromium dichloride concentration test, it is necessary to ensure that it does not react with other substances except chromium dichloride, otherwise V2 will be too large, resulting in inaccurate testing. Table 2 lists commonly used oxidants:

[0088] Table 2: Common oxidants and their characteristics analysis

[0089]

[0090] Note: √ indicates that the two can react, and X indicates that the two do not react.

[0091] According to Table 2, the Cr content in the electrolyte was analyzed by analyzing the oxidizing properties of common oxidants and combining the material components contained in the electrolyte. 2+ The concentration of the available oxidant types. Therefore, this embodiment uses ferric chloride as the oxidant.

[0092] S3. Take some analytically pure ferrous chloride solid medicine, dilute it with pure water, and prepare a solution containing 0.05-0.2 mol / L of ferric chloride. The concentration is recorded as C0. For example, take 16.2204g of dried ferric chloride solid powder in a 100ml beaker, add 50ml of pure water and 10ml of concentrated hydrochloric acid to dilute it, then put it into a 100ml volumetric flask and make up the volume with pure water to obtain 100ml of acidic ferric chloride solution titrant containing 0.1001mol / L, and put it into an inert atmosphere system for standby use.

[0093] S4. In an inert atmosphere system, take some of the above electrolyte and dilute it 100 to 300 times. For example, take 0.25 ml of the electrolyte and dilute it to 50 ml with pure water. Record it as V1. This is the test solution 11-6.

[0094] S5. In the inert atmosphere system, the host 11-1 is turned on, so that the titrant 11-2 is pumped into the burette 11-3, and further, can be pumped into the test liquid 11-6;

[0095] S6, wherein the titrant discharge rate can be set during the operation of step 4. In the embodiment, it can be set to 25 μl / s. The discharge rate can be set according to the volume of the liquid to be tested and the estimated concentration to reduce the titration test error;

[0096] S7, in the inert atmosphere system, observe the potential monitoring system 11-7, and simultaneously record the amount of titrant used and the potential, which changes according to the electrode test potential during the reaction between the titrant and the test solution;

[0097] S8, wait until the potential jumps, record the amount of titrant used V2, the potential U1, and the chromium dichloride concentration C1 in the electrolyte to be tested can be calculated using the following formula:

[0098] C1=C0*V2 / V1

[0099] Using the above method to test the concentration of chromium dichloride in the electrolyte can control the error within ±3%, meeting the needs of technology research and development and engineering application promotion.

[0100] S9. Repeat steps 3 to 7 for 3 to 5 times, and take the average value of multiple tests to further reduce the error.

[0101] Example 1

[0102] S1: Use a 1000ul pipette to take 0.5ml of the electrolyte sample 1 to be tested and place it in the titration cup;

[0103] S2: Further, add pure water from which dissolved oxygen has been removed to dilute to about 40 ml;

[0104] S3: Further, the titration cup is placed on the titration table, and the stirring rod, the composite platinum ring electrode, and the burette are inserted 1-2 cm below the liquid surface of the solution;

[0105] S4: Further, click on stirring, and click on the host to start the titration test;

[0106] S5: Further, after the automatic titration is completed, the electrode potential value and the change rate value are recorded to obtain a curve of the electrode potential and the change rate thereof with the volume of the titrant consumed;

[0107] S6: Record the titrant consumption at the sudden point where the potential changes with the volume of the titrant, i.e. V2, and calculate the Cr of the sample to be tested. 2+ concentration;

[0108] S7: Figure 4 It is the change process of potential and potential change rate during the titration test of sample 1. According to the figure, a sudden change of potential occurs at point A, so the volume of titrant corresponding to point A is V2, and the volume of titrant consumed in this sample is 0.642ml;

[0109] S8: According to formula (1), it can be calculated that the concentration of chromium dichloride in sample 1 is 0.13M;

[0110] S9: Repeat the test twice to obtain titrant consumption of 0.621 ml and 0.635 ml respectively, and calculate the concentration of chromium dichloride to be 0.126 M and 0.129 M respectively. The parallel error is less than 2%.

[0111] Embodiment 2:

[0112] S1: Use a 1000ul pipette to take 0.5ml of the electrolyte sample 1 to be tested and place it in the titration cup;

[0113] S2: Further, add pure water from which dissolved oxygen has been removed to dilute to about 40 ml;

[0114] S3: Further, the titration cup is placed on the titration table, and the stirring rod, the composite platinum ring electrode, and the burette are inserted 1-2 cm below the liquid surface of the solution;

[0115] S4: Further, click on stirring, and click on the host to start the titration test;

[0116] S5: Further, after the automatic titration is completed, the electrode potential value and the change rate value are recorded to obtain a curve of the electrode potential and the change rate thereof with the volume of the titrant consumed;

[0117] S6: Record the titrant consumption at the sudden point where the potential changes with the volume of the titrant, i.e. V2, and calculate the Cr of the sample to be tested. 2+ concentration.

[0118] S7: Figure 5 It is the change process of potential and potential change rate during the titration test of sample 2. The volume of titrant corresponding to point A is V2, and the volume of titrant consumed in the sample is 2.249 ml;

[0119] S8: According to formula (1), it can be calculated that the concentration of chromium dichloride in sample 1 is 0.45M;

[0120] S9: The experiment was repeated twice to obtain titrant consumption of 2.245 ml and 2.257 ml respectively, and the concentrations of chromium dichloride were calculated to be 0.451 M and 0.452 M respectively, with a parallel error of less than 2%.

[0121] Finally, it should be noted that the above is only a preferred embodiment of the present invention and is not intended to limit the present invention. Although the present invention has been described in detail with reference to the aforementioned embodiments, it is still possible for those skilled in the art to modify the technical solutions described in the aforementioned embodiments or to make equivalent substitutions for some of the technical features therein. Any modifications, equivalent substitutions, improvements, etc. made within the spirit and principles of the present invention should be included in the protection scope of the present invention.

Claims

1. A system for testing the concentration of chromium dichloride in an electrolyte, characterized in that: The system comprises an inert atmosphere device and a testing device, wherein: The testing device is arranged inside the inert atmosphere device; The testing device is provided with a potential monitor and a titration sub-device inside; The inert atmosphere device comprises: a box, a first pipeline, a second pipeline, rubber gloves, a transfer port and an oxygen detector, wherein: A first hole is provided on the first side of the box body; one end of the first pipe is connected to the box body through the first hole; The second side of the box body is provided with a transmission port and a second hole; one end of the second pipe is connected to the second side of the matching box body through the second hole; A rubber glove is arranged on the third side of the box body, and the rubber glove is sealed and connected to the box body through a sealing ring; An oxygen detector is arranged on the top of the box.

2. The chromium dichloride concentration testing system in the electrolyte according to claim 1, characterized in that: The inert atmosphere device also includes: a stop valve, a sealing ring and an inert gas cylinder, wherein: The first hole and the second hole are both provided with sealing rings; The other end of the first pipeline is connected to the outside world; a stop valve is arranged on the other end of the first pipeline connected to the outside world; An inert gas cylinder is connected to the other end of the second pipeline.

3. The chromium dichloride concentration testing system in the electrolyte according to claim 2, characterized in that: A first pressure reducing valve is arranged at the outlet of the inert gas cylinder, and the other end of the second pipeline is connected to the inert gas cylinder through the first pressure reducing valve.

4. The chromium dichloride concentration testing system in the electrolyte according to claim 3, characterized in that: The second pipeline is provided with a second pressure reducing valve, and the second pressure reducing valve is located between the box body and the first pressure reducing valve.

5. The chromium dichloride concentration testing system in the electrolyte according to claim 1, characterized in that: The titration sub-device includes a main unit, a sealed bottle, a burette, a stirrer and a test bottle, wherein: The sealed bottle is used to hold the titrant, and the test bottle is used to hold the liquid to be tested; The sealed bottle is connected to the burette inlet through a first pipeline, and the burette outlet is connected to the test bottle through a second pipeline; The host is internally integrated with a burette driver, which is connected to the burette and is used to push the titrant in the sealed bottle along the pipeline through the burette into the test bottle; The stirrer and the potential detector are both arranged inside the test bottle.

6. The chromium dichloride concentration testing system in the electrolyte according to claim 5, characterized in that: The test device also includes a fixture, The holder is used to fix the stirrer and / or the potential detector.

7. The chromium dichloride concentration testing system in the electrolyte according to claim 5, characterized in that: The potential detector includes an indicator electrode and a reference electrode; The host is connected to the indicator electrode and the reference electrode, and is used to detect the potential change caused by the redox reaction process of the titrant and the liquid to be tested.

8. A method for testing the concentration of chromium dichloride in an electrolyte, characterized in that: Using the test system as described in any one of claims 1 to 7, the method includes: The inert atmosphere device is filled with inert gas; The titrant and the test liquid are placed in a sealed bottle and a test bottle respectively; wherein the potential monitor penetrates into the test liquid; The test device is turned on, and the stirrer stirs the test liquid at a predetermined stirring speed. The titrant in the sealed bottle is pumped into the burette along the first pipeline, and the titrant in the burette is pushed into the test bottle along the second pipeline at a predetermined titration speed to undergo a redox reaction with the test liquid. When the potential monitor detects the potential change of the test solution after the redox reaction occurs, the titration is stopped and the amount of titrant used at this time is recorded.

9. The method for testing the concentration of chromium dichloride in an electrolyte according to claim 8, characterized in that: The process of filling the inert gas into the inert atmosphere device includes: include, The oxygen detector monitors the gas composition in the box online. When the oxygen concentration reaches 20ppm or above, open the first valve to 0.3-0.6MPa and the second valve to 0.3-0.6Mpa, open the stop valve, and purge the box until the oxygen concentration reaches 20ppm or below and maintains for a predetermined time, and adjust the second pressure reducing valve 10 to 0.15-0.3Mpa.

10. The method for testing the concentration of chromium dichloride in an electrolyte according to claim 8, characterized in that: The method further comprises obtaining the liquid to be tested, comprising the following steps: The electrolyte to be tested containing chromium dichloride is diluted 100 to 300 times to obtain a solution to be tested.

11. The method for testing the concentration of chromium dichloride in an electrolyte according to claim 8, characterized in that: The method further comprises preparing a titrant; The titrant is a ferric chloride solution, and the concentration of the ferric chloride solution is 0.05-0.2 mol / L.

12. The method for testing the concentration of chromium dichloride in an electrolyte according to claim 10, characterized in that: The calculation formula for the concentration of chromium dichloride in the electrolyte to be tested is as follows: C1=C0*V2 / V1 Wherein, C1 represents the concentration of chromium dichloride in the electrolyte to be tested, C0 represents the concentration of ferric chloride in the titrant, V2 represents the volume of the titrant participating in the redox reaction, and V1 represents the total volume of the test solution after dilution.

13. Use of the system according to any one of claims 1 to 7 in testing the concentration of chromium dichloride ions in an electrolyte of an iron-chromium flow battery.

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