Study On Recycling Of Spent Lithium Ion Batteries Containing Cobalt And Pilot Scale Experiment

With widely use of portable devices, the demand of lithium-ion batteries isincreasing rapidly. Lithium cobalt oxide batteries have the best performance and thelargest share in the market. Most lithium-ion batteries will be waste after severalyears’ use. These waste batteries will have significant hazards for environmental andhuman health if not being processed correctly. However, the spent lithium-ionbatteries contain lots of valuable metals, such as cobalt, copper, etc, which cancreate good economic benefits through recycling of spent lithium-ion batteries.This paper mainly focused on recovering and reuseing spent lithium cobaltoxide batteries, exploring the best recovery technology and conditions of eachprocess from a single block to pilot scale test. Then lithium cobalt oxide will besynthetized useing recycled cobalt oxide.Cobalt oxalates were made through following steps. Firstly, useing graphite asdischarge medium to release the remaining charges of spent lithium cobalt oxidebatteries. Secondly, the shell, separator, and fragments of positive and negative platewere separated by crushing the batteries. Thirdly, the fragments were soaking with1.5M NaOH for15min to remove the positive electrode collector, following the0.5mm macropore filter of the fragments to remove the negative electrode currentcollector, and filtered ordinarily to achieve the active materials. Fourthly, lithiumcobalt oxide were dissolved with2.5M H2SO4+H2O2O₂system for2h, following theaddition of oxalate with a proportion of1:1.2to get cobalt element and of sodiumcarbonate to get lithium element.Pilot scale test of recycling lithium cobalt oxide batteries were carried out byenlarging the laboratory process. There had two difficulties in pilot scale test-shellwas not easy to screen and product contained impurities. These difficulties weresolved by controlling the time of alkali-leaching in15min or high temperaturetreated at650℃for2h and selecting the extraction agent P204.Co3O4were obtained by sintering cobalt oxalate for6hours at350℃, whichwas general material to synthesize lithium cobalt oxide. Then using cobalt oxide ascobalt source and lithium hydroxide as lithium source to synthesize lithium cobaltoxide and assembling a coin cell battery to teste its electrochemical properties. Theinitial specific discharge capacity was more than160mAh/g, which is almost thesame with commercially lithium cobalt oxide materials. However, the capacitywould decline fastly with battery circulation, dropping to120mAh/g after100cycles, and the rate of energy retention was75%. To solve the poor performance of recycle,magnesium or nickel element could be added to form ternary material with cobaltand impurity aluminum.