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CN-121994990-A - Electrolyte moisture detection reagent and detection method

CN121994990ACN 121994990 ACN121994990 ACN 121994990ACN-121994990-A

Abstract

The application relates to an electrolyte moisture detection reagent and a detection method, which are particularly suitable for trace moisture detection of lithium ion battery electrolyte, and comprise, by mass, 4% -15% of iodine, 6% -20% of sulfur dioxide, 20% -45% of alcohol ether compounds, 20% -45% of amide compounds, 0.5% -1.2% of tris (pentafluorophenyl) borane and 0.3% -0.8% of sulfamic acid, wherein the total content of the alcohol ether compounds and the amide compounds is 65% -90%, and preferably does not contain hydroxyl. Tris (pentafluorophenyl) borane is used to complex fluoride ions to eliminate HF interference and sulfamic acid is used to neutralize the interference of reducing additives such as vinylene carbonate. The corresponding detection method uses the reagent, can control the environmental humidity by combining with an annular space air curtain, and solves the problem of large error caused by chemical interference when the traditional karl fischer method is used for measuring the electrolyte moisture.

Inventors

  • Su Yanke
  • ZHOU QINGZE

Assignees

  • 江苏远航锦锂新能源科技有限公司

Dates

Publication Date
20260508
Application Date
20260316

Claims (10)

  1. 1. The electrolyte moisture detection reagent is characterized by comprising the following components in percentage by mass: Iodine 4-15% 6 To 20 percent of sulfur dioxide Alcohol ether compound 20-45% 20 To 45 percent of amide compound 0.5 To 1.2 percent of tris (pentafluorophenyl) borane Sulfamic acid 0.3-0.8% Wherein the total mass percentage of the alcohol ether compound and the amide compound is within the range of 65-90 percent.
  2. 2. The electrolyte moisture detection reagent according to claim 1, wherein the amide compound is an amide compound having no hydroxyl group, and the alcohol ether compound is an alcohol ether compound having no hydroxyl group.
  3. 3. The electrolyte moisture detection reagent according to claim 2, wherein the alcohol ether compound is one or a combination of a plurality of propylene glycol dimethyl ether, triethylene glycol dimethyl ether, tetraethylene glycol dimethyl ether, hexylene glycol dimethyl ether, and hexaethylene glycol dimethyl ether.
  4. 4. The electrolyte moisture detection reagent according to claim 2, wherein the amide compound comprises one or more of fluoro formamide, chloro formamide, iodo formamide, bis fluoro formamide, bis chloro formamide, bis iodo formamide, fluoro acetamide, chloro acetamide, iodo acetamide, poly fluoro acetamide, poly chloro acetamide, poly iodo acetamide.
  5. 5. The electrolyte moisture detection reagent according to claim 1, further comprising a stabilizer, wherein the mass percentage of the stabilizer is in the range of 1% -10%, and the stabilizer is carbon trichloride, carbon tetrachloride or trifluorotrichloroethane.
  6. 6. The electrolyte moisture detecting reagent according to claim 1, wherein the pH of the reagent is controlled within a range of 4 to 6.5.
  7. 7. The electrolyte moisture detection reagent of claim 1, further comprising an inorganic salt, wherein the inorganic salt is ammonium chloride, lithium chloride, or sodium nitrate.
  8. 8. The electrolyte moisture detection reagent of claim 7, wherein the conductivity at 20 ℃ is greater than 20mS/cm.
  9. 9. An electrolyte moisture detection method, characterized in that the electrolyte moisture detection reagent according to any one of claims 1 to 7 is used.
  10. 10. The method for detecting moisture in an electrolyte according to claim 9, wherein the humidity of the detection site is controlled to be within 0.5% by using an annular air curtain.

Description

Electrolyte moisture detection reagent and detection method Technical Field The application relates to the technical field of lithium ion batteries, in particular to an electrolyte moisture detection reagent and a detection method. Background In lithium ion battery fabrication, the trace moisture content of the electrolyte is a parameter that affects battery performance, cycle life, and safety, and is typically required to be controlled below twenty parts per million (20 ppm). At present, the detection technology based on a Karl Fischer method, in particular a coulometric method, is adopted for the determination of the water content of the electrolyte in the industry, and the water content in the sample is calculated by accurately detecting the consumption of iodine in the titration reaction according to the chemical principle that the iodine elemental sulfur dioxide needs quantitative participation of water. In order to improve the accuracy of the karl-fischer method in a complex electrolyte system, various improvements and certain progress have been made in the industry aiming at main interfering substances thereof, a pretreatment tube of calcium fluoride (CaF 2) is adopted for absorbing HF generated by the hydrolysis of LiPF 6 in the electrolyte for hydrogen fluoride interference, or pyridine derivatives are added in the electrolyte to neutralize acidic substances, and a heating pretreatment of 120 ℃ is adopted for VC interference so as to decompose a VC additive in advance. However, the existing solutions have defects, and cannot meet urgent requirements of industries on high-precision, high-reliability and low-cost detection, and the problems are that calcium fluoride solids form precipitates to block a detection system pipeline, frequent maintenance is needed, the continuity of detection is damaged, the added pyridine substances cannot completely inhibit subsequent hydrolysis of PF 5, residual interference is large, and detection errors still exceed 50 ppm. The heating method can lead to volatilization of low boiling point solvents such as dimethyl carbonate and the like while decomposing VC, thereby changing the original composition of the electrolyte and distorting the detection result. In view of the above, the prior art is limited by the defects of the chemical interference being unable to eradicate, and therefore, a detection reagent and method capable of overcoming the chemical interference of HF and VC needs to be developed. Disclosure of Invention The application aims to provide a detection reagent and a detection method capable of eliminating interference of HF and VC in lithium ion battery electrolyte on Karl Fischer titration, which are particularly suitable for trace moisture detection of the lithium ion battery electrolyte. Iodine 4-15% 6 To 20 percent of sulfur dioxide Alcohol ether compound 20-45% 20 To 45 percent of amide compound 0.5 To 1.2 percent of tris (pentafluorophenyl) borane Sulfamic acid 0.3-0.8% Wherein the total mass percentage of the alcohol ether compound and the amide compound is within the range of 65-90 percent. In one embodiment, the amide compound is an amide compound containing no hydroxyl group, and the alcohol ether compound is an alcohol ether compound containing no hydroxyl group. In one embodiment, the alcohol ether compound is one or a combination of more of propylene glycol dimethyl ether, triethylene glycol dimethyl ether, tetraethylene glycol dimethyl ether, hexanediol dimethyl ether and hexaethylene glycol dimethyl ether. In one embodiment, the amide compound includes one or more of fluoro formamide, chloro formamide, iodo formamide, bis fluoro formamide, bis chloro formamide, bis iodo formamide, fluoro acetamide, chloro acetamide, iodo acetamide, poly fluoro acetamide, poly chloro acetamide, poly iodo acetamide. In one embodiment, the stabilizer is carbon trichloride, carbon tetrachloride or trifluorotrichloroethane, and the mass percentage of the stabilizer is in the range of 1-10%. In one embodiment, the pH of the reagent is controlled in the range of 4-6.5. In one embodiment, an inorganic salt is also included, which is ammonium chloride, lithium chloride, or sodium nitrate. In one embodiment, the conductivity is greater than 20mS/cm at 20 ℃. In addition, the application also provides an electrolyte moisture detection method, which uses the electrolyte moisture detection reagent. In one embodiment, an annular air curtain is used to control the humidity of the test bits to within 0.5%. Compared with the prior art, the application has the following beneficial effects: The electrolyte moisture detection reagent and the detection method provided by the application are particularly suitable for trace moisture detection of lithium ion battery electrolyte, and the tris (pentafluorophenyl) borane in the detection reagent is used as a strong Lewis acid, and can be preferentially and efficiently combined with trace water in the electrolyte in a competitive manne