Recovery Of Titanium And Lithium From Spent Li₄Ti₅O₁₂Electrode Material

Lithium titanate (Li4Ti5O12) battery has been widely used as an alternative way to classical rechargeable battery in the new energy vehicles and electric motorcycles, etc., due to its many advantages, such as high stability, high security, fast to charge and high current. Beyond that, this battery has been deployed in their lithium titanate energy storage systems for electric grid ancillary services and in various military applications. A large amount of usage of Li4Ti5O12battery would lead to the serious environmental pollution if the spent lithium titanate batteries are not employed as the second resources.A promising process for recovering titanium and lithium from spent lithium titanate battery and producing TiO2nano-scale powders is proposed in this paper. In the pretreatment, current collectors were treated with NaOH to dissolve Al and calcined at400℃to burn off polyvinylidene fluoride (PVDF) and carbon. The spent Li4Ti5O12is treated with H2SO4together with H2O2to dissolve lithium and titanium. Various process parameters such as the concentration of sulphuric acid and H2O2, leaching temperature are examined in terms of metal leaching efficiency. Then, a study of selectively separated titanium from the leaching liquor by solvent extraction using primary amine N1923is conducted. Finally, nano-scale TiO2powders are synthesized via homogeneous precipitation using urea and sodium dodecyl benzene sulfonate (SDBS, C18H29NaO3S).Based on the experiment of the leaching process, the use of a reductive agent H2O2was found essential to accelerate the dissolution process. Meanwhile, the leaching time also significantly influenced metal recovery. In this investigation, reductive acid leaching of the spent lithium titanate for4h at80℃with4M H2SO4,20vol.%H2O2and0.025g/mL solid-to-liquid ratio resulted in high leaching efficiencies of Ti (98%) and Li (97%). The extraction studies showed that the Ti extraction percentage achieved98.8%at30vol.%extractant concentration with O/A ratio2:1at10min of mixing time, while the solvent extraction efficiency of lithium is only1.4%. The effects of operating temperature on the extraction efficiency were found to be uselessness. The loaded with titanium can be effective stripped with2M H2SO4at ambient temperature, affording98%stripping efficiency. The raffinate was concentrated from0.74g/L to1.11g/L by evaporation, then lithium carbonate was precipitated by adding saturated solution of sodium carbonate affording85%recovery. In the case of synthesis of nanoscale TiO2, a series of parameters including the concentration of Ti and urea, temperature and time which have effect on production rate and crystal size of nano TiO2were studied by weigh and SEM. The XRD result reveals that anatase phase is the main constituent. The SEM image of the hydrolyzed product indicates the particle size is about100nm.