| 摘要 |
PURPOSE:To improve the characteristic of a battery by removing acid impurity by adding a specified treatment agent in recrystallizing crude LiPF6 in an organic solvent so as to neutralize the solution in manufacturing a solute for a nonaqueous electrolyte consisting of LiPF6. CONSTITUTION:Crude LiPF6 containing acid impurity is first dissolved in an organic solvent. As the organic solvent, a matter of a high permittivity having a polar group such as an ether bond or an ester bond is preferably used. At this point, the temperature of the solution reaches 60-70 deg.C due to the heat of the dissolution. After that, the solution is neutralized with a Li compound or an amine while maintaining the temperature by external heating. The neutralizing agent may be anything which can combine with acid impurity especially hydrogen fluoride to form a salt or a complex compound. The ratio of the neutralizing agent to crude LiPF6 is 1-20pts.wt. to 100pts.wt. After the neutralization treatment, the solution is filtered while being maintained at the above temperature to remove excessive amounts of the treatment agent and reaction products dispersed and suspended in it. Following that, when the filtrate is cooled to around room temperature, LiPF6 contained in the filtrate crystallizes and deposits which is then filtered off thereby obtaining desired purified LiPF6. |
