Study On The Regeneration Of Lithium Cobalt Oxide From Spent Lithium Cobalt Oxide Batteries By Sol-gel Method

Lithium cobalt oxide batteries are widely used in small electric equipments such as mobile phones,cameras,laptops,etc.However,a large amount of spent lithium cobalt oxide batteries will be produced inevitably since the service life of lithium cobalt oxide battery is only 3?5 years.Spent lithium cobalt oxide batteries contain a variety of metal resources,and also contain a variety of harmful substances.If we ignored the disposal of these spent lithium cobalt oxide batteries,it will inevitably lead to the waste of resources and environmental damage.In this study,the acid leaching and regeneration process were coupled to regenerate LiCoO2 from the cathode material of the spent lithium battery in one step,which simplifies the overall process.The pretreatment process,acid leaching process,regeneration process and modification process of the recycling process flow were studied separately.Then,the positive electrode material was separated from the current collector by NMP using a solvent method,and then the positive electrode material was calcined at 600? for 5 h to remove residual impurities such as polyvinylidene fluoride(PVDF)and acetylene black to obtain pure LiCoO2.In the process of acid leaching,citric acid was used as leaching agent,and H2O2 was used as reducing agent.Under the leaching condition with 1.5 mol/L of citric acid,H2O2 concentration of 2 vol%,reaction time of 60 min,temperature of 80? and solid-liquid ratio of 20 g/L,the LiCoO2 obtained by the pretreatment was leached to prepare a leach solution containing Li+and Co2+.In the process of regeneration and modification,the concentration of Li+and Co2+ in the leaching solution was determined by ICP-OES,and the corresponding cobalt source or lithium source was added to the leaching solution to adjust the ratio of Li+and Co2+ to 1:1.Then,the adjusted solution was stirred at 80? until the sol was formed,then dried under vacuum conditions at 80?for 24 h to obtain xerogel.Finally,the xerogel was calcined at 700?for 6 h to obtain the regenerated LiCoO2.Magnesium metal salts were also added to the adjusted leaching solution to obtain Mg doped LiCoO2.Electrochemical characterization showed that magnesium doping enhances cycle performance and rate performance of LiCoO2 at high voltage.