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CN-122010146-A - Production method and production system of lithium hexafluorophosphate solution

CN122010146ACN 122010146 ACN122010146 ACN 122010146ACN-122010146-A

Abstract

The patent discloses a production method and a production system of lithium hexafluorophosphate solution, wherein in the production process, lithium fluoride solids continuously enter a first ball milling reactor, and PF 5 -containing raw material gas continuously enters a second ball milling reactor. The production method comprises the steps of reacting lithium fluoride solids with PF 5 -containing gas in a first ball milling reactor to obtain lithium hexafluorophosphate, then enabling the lithium fluoride solids and unreacted lithium fluoride solids to enter a second ball milling reactor together, enabling the PF 5 -containing gas to come from gas-phase products of the second ball milling reactor, reacting the lithium fluoride from the first ball milling reactor with PF 5 -containing raw material gas in the second ball milling reactor, enabling obtained lithium hexafluorophosphate crude products to continuously enter a third ball milling reactor, enabling the gas-phase products to continuously enter the first ball milling reactor, enabling residual gas in the lithium hexafluorophosphate crude products to be removed in the third ball milling reactor, enabling the lithium hexafluorophosphate solid to enter a fourth ball milling reactor, enabling the lithium hexafluorophosphate solid to be dissolved in carbonate solvent, and filtering the solution to obtain lithium hexafluorophosphate solution. The gas-solid phase production process of lithium hexafluorophosphate provided by the invention has the advantages of high raw material utilization rate, safe and efficient reaction, continuous and stable production and the like.

Inventors

  • WU HAIFENG
  • GONG DANGSHENG
  • HU TAOTAO
  • ZHANG YONGYAO
  • CHEN XIANJIN
  • CHEN XIAOPING
  • WEI YOUCHANG

Assignees

  • 浙江蓝天环保高科技股份有限公司
  • 中化蓝天集团有限公司

Dates

Publication Date
20260512
Application Date
20241111

Claims (16)

  1. 1. A production method of a lithium hexafluorophosphate solution is characterized in that in the production process, lithium fluoride solids enter a first ball milling reactor, a raw material gas containing PF 5 is introduced into a second ball milling reactor, and the production method comprises the following steps: In the first ball milling reactor, lithium fluoride solid reacts with PF 5 -containing gas to obtain lithium hexafluorophosphate, and then the lithium hexafluorophosphate and unreacted lithium fluoride solid enter a second ball milling reactor together, wherein the PF 5 -containing gas is a gas phase product from the second ball milling reactor; In the second ball milling reactor, lithium fluoride from the first ball milling reactor reacts with the raw material gas containing PF 5 , the obtained lithium hexafluorophosphate crude product continuously enters the third reactor, and the obtained gas phase product continuously enters the first ball milling reactor; In the third reactor, the residual gas in the crude lithium hexafluorophosphate is removed, and then enters a fourth reactor; In the fourth reactor, the lithium hexafluorophosphate solid is dissolved in a carbonate solvent, and a lithium hexafluorophosphate solution is obtained after filtration.
  2. 2. The method for producing a lithium hexafluorophosphate solution according to claim 1, wherein the PF 5 -containing raw material gas comprises PF 5 gas, HCl gas, and HF gas.
  3. 3. The method for producing a lithium hexafluorophosphate solution according to claim 2, wherein the PF 5 -containing raw material gas is prepared from phosphorus pentachloride and hydrogen fluoride or from phosphorus trichloride, hydrogen fluoride and liquid chlorine.
  4. 4. The method of producing a lithium hexafluorophosphate solution according to claim 1, wherein the molar ratio of the added lithium fluoride solid to PF 5 in the PF 5 -containing gas in the first ball milling reactor is (1-100): 1.
  5. 5. The method of producing a lithium hexafluorophosphate solution according to claim 4, wherein the residence time of the reaction material in the first ball milling reactor is 10 to 600 seconds.
  6. 6. The method for producing a lithium hexafluorophosphate solution according to claim 4, wherein the reaction temperature is-15 to 80℃and the reaction pressure is 0 to 1.5MPa in the first ball milling reactor.
  7. 7. The method for producing a lithium hexafluorophosphate solution according to claim 1, wherein the molar ratio of unreacted lithium fluoride from the first ball milling reactor to PF 5 in the feed gas containing PF 5 in the second ball milling reactor is 1 to 100.
  8. 8. The method for producing a lithium hexafluorophosphate solution according to claim 7, wherein the residence time of the reaction material in the second ball milling reactor is 10 to 600 seconds.
  9. 9. The method for producing a lithium hexafluorophosphate solution according to claim 7, wherein the reaction temperature is-15 to 80℃and the reaction pressure is 0 to 1.5MPa in the second ball milling reactor.
  10. 10. The method for producing lithium hexafluorophosphate solution according to claim 1, wherein the third reactor is set at a vacuum degree of 0.08MPa or more and at a temperature of 0-80 ℃, and residual HCl gas and HF gas in the crude lithium hexafluorophosphate are removed.
  11. 11. The method for producing a lithium hexafluorophosphate solution according to claim 1, wherein the water content of the carbonate solvent in the fourth reactor is 20ppm or less and is at least one selected from the group consisting of dimethyl carbonate (DMC), diethyl carbonate (DEC), ethylmethyl carbonate (EMC), ethylene carbonate (VC) and Propylene Carbonate (PC).
  12. 12. The method for producing a lithium hexafluorophosphate solution according to claim 11, wherein the dissolution temperature is controlled to be 0 to 50℃in the fourth reactor to prevent decomposition of the material.
  13. 13. The method for producing a lithium hexafluorophosphate solution according to claim 1, wherein the lithium hexafluorophosphate solution obtained in the fourth reactor is subjected to filtration to remove insoluble matters, thereby obtaining a lithium hexafluorophosphate solution product.
  14. 14. A production system of lithium hexafluorophosphate solution for the production of the lithium hexafluorophosphate solution according to any one of claims 1 to 13, characterized in that the production system comprises: The lithium fluoride solid enters the first ball milling reactor through a first feeding bin to react with a gas-phase product stream output from the second ball milling reactor, the obtained solid product stream of lithium hexafluorophosphate and unreacted lithium fluoride enters the second ball milling reactor, and the reacted gas-phase product stream is discharged out of the first ball milling reactor; The solid product of the first ball milling reactor flows through a second feeding bin to enter the second ball milling reactor, reacts with the PF 5 -containing raw material gas which is introduced into the second ball milling reactor, the obtained lithium hexafluorophosphate crude product enters a third reactor, and the obtained gas phase product flow enters the first ball milling reactor; The third reactor is a tubular reactor with double screws, and after the lithium hexafluorophosphate crude product enters the third reactor, residual gas is removed in a negative pressure state and then enters a fourth reactor; And the fourth reactor is a reaction kettle and is used for stirring and dissolving the lithium hexafluorophosphate crude product, and the obtained lithium hexafluorophosphate solution is filtered to remove insoluble substances to obtain a lithium hexafluorophosphate solution product and is stored in a storage device.
  15. 15. The system for producing lithium hexafluorophosphate solution according to claim 14, wherein the first ball-milling reactor and the second ball-milling reactor are double-layer straight-tube dry ball-milling machines.
  16. 16. The lithium hexafluorophosphate solution production system according to claim 15, wherein the double-layer straight-barrel dry ball mill is composed of a barrel body, a motor and a support, the barrel body is divided into an inner layer and an outer layer by a straight-barrel plate, grinding balls are filled in the inner layer and the outer layer, the grinding balls can perform grinding reaction on materials, an outer layer feeding hole, an outer layer discharging hole, an inner layer feeding hole and a lateral line discharging hole are formed in the outer layer barrel body, a heat exchange jacket is arranged on the outer side of the barrel body, and a heat exchange medium inlet and outlet are formed in the heat exchange jacket.

Description

Production method and production system of lithium hexafluorophosphate solution Technical Field The invention relates to lithium ion battery electrolyte, in particular to a production method and a production system of lithium hexafluorophosphate solution. Background Compared with the traditional battery, the lithium ion battery has larger capacitance and higher output voltage, and the cycle performance and the conductivity performance are obviously improved, so that the lithium ion battery is widely applied to the fields of electronics, information, computers, military, aerospace, power automobiles, electric vehicles and the like. Lithium hexafluorophosphate (LiPF 6) has good ionic conductivity and electrochemical stability due to small radius of fluorine atom, small electronegativity and proper radius of PF 6-, and is the most widely used electrolyte salt in the current commercial lithium ion battery. In recent decades, the lithium battery industry develops rapidly, the upstream industry is driven to develop rapidly, the demand of lithium hexafluorophosphate is continuously increased, and the preparation method of the lithium hexafluorophosphate is researched as an industry hotspot. At present, the preparation route of lithium hexafluorophosphate mainly comprises a gas-solid direct reaction method, an HF solvent method, an organic solvent method and an ion exchange method, wherein the most studied process, the most mature technology and the most widely applied industrial process are the HF solvent method. The HF solvent method adopts phosphorus pentachloride (PCl 5) and HF as raw materials to generate phosphorus pentafluoride (PF 5) and HCl gas, then PF 5 and HCl mixed gas react with lithium fluoride (LiF) in the HF solvent to generate lithium hexafluorophosphate (LiPF 6), and finally LiPF 6 crystal is obtained through a cooling crystallization process. The process has the advantages of high raw material utilization rate, almost no byproducts, high product purity, capability of realizing long-period circulation of HF and the like. However, anhydrous HF has strong corrosiveness, is toxic and harmful, is very dangerous in the reaction process, can cause great harm to the environment and personnel when any leakage occurs, and has high requirements on equipment corrosion resistance, production environment and personnel operation safety. Meanwhile, the crystallization process is not easy to control and the crystallization time is long, so that the production efficiency is low. The organic solvent method is a method for synthesizing lithium hexafluorophosphate in a carbonate solvent, and because the carbonate is a solvent for preparing electrolyte, the synthesized lithium hexafluorophosphate carbonate solution does not need to additionally separate the solvent and the lithium hexafluorophosphate, thereby saving complicated crystallization flow and equipment, obviously improving the production efficiency and reducing the production cost. However, the method still needs to use anhydrous HF with strong corrosiveness, equipment and safety problems cannot be solved, or the method needs to prepare and obtain high-purity PF 5 gas and then react with carbonate solution of lithium fluoride, but the preparation of the high-purity PF 5 gas is difficult and high in cost, and the anhydrous HF still needs to be used in the preparation process. Patent US20010041158A1, CN104261369A, CN116514081A, CN101570328A, CN102491305a and the like all disclose a method for preparing hexafluorophosphoric acid (HPF 6) aqueous solution by reacting with HF and then preparing PF 5 by reacting with dehydrating agent sulfur trioxide or fuming sulfuric acid by taking oxygen-containing phosphorus source (orthophosphoric acid, polyphosphoric acid, phosphorus pentoxide and the like) as raw material. The method for preparing the high-purity PF 5 can realize the purification of PF 5 gas by multistage pressurization rectification, and the environment containing strong acid has the problems of serious equipment corrosion, disposal of byproduct fluorine-containing sulfate and the like. The gas-solid method preparation of lithium hexafluorophosphate is the earliest process, and is simple to operate and does not need solvent. However, in the gas-solid reaction process, after LiPF 6 is formed on the surface of LiF, internal LiF cannot contact and react with PF 5, so that the utilization rate of LiF is low and the reaction effect is poor. Therefore, there is a need to increase the conversion rate of lithium fluoride by improving the state or reaction form of lithium fluoride. In 1950, U.S. fluorine scientist j.h.simmons reacted directly with PF 5 gas and porous LiF (pretreated with anhydrous HF) in a nickel vessel under high temperature and pressure conditions to produce LiPF 6. However, liPF 6 generated by the method completely coats LiF solid particles, and prevents further reaction, so that the obtained lithium hexafluorophosphate product has low purity an