Comparing the environmental impact of different hydrometallurgical processes for the recycling of lithium-ion batteries using a life cycle assessment approach

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dc.contributor.advisorDorfling, Christieen_ZA
dc.contributor.advisorAkdogan, Guvenen_ZA
dc.contributor.authorMaritz, Roelof Fredericken_ZA
dc.contributor.otherStellenbosch University. Faculty of Engineering. Dept. of Chemical Engineering. Process Engineering.en_ZA
dc.date.accessioned2024-03-05T08:57:16Zen_ZA
dc.date.accessioned2024-04-26T13:27:55Zen_ZA
dc.date.available2024-03-05T08:57:16Zen_ZA
dc.date.available2024-04-26T13:27:55Zen_ZA
dc.date.issued2024-03en_ZA
dc.descriptionThesis (PhD)--Stellenbosch University, 2024.en_ZA
dc.description.abstractENGLISH ABSTRACT: Lithium-ion batteries (LIBs) have become commonplace for everyday use in consumer electronics. These batteries have also gained a lot of popularity recently for usage in larger scale application such as electric vehicles (EV). The LIB market is projected to grow from 700 GWh in 2022 to 4.7 TWh in 2030 (Fleischmann et al., 2023). The consequence of this rapidly increasing demand for LIBs is the formation of a fast-growing end-of-life (EOL) LIB waste stream. This waste stream includes valuable metals such as lithium, cobalt, nickel, and manganese to potentially be recycled, thus providing benefits in terms of waste management and income from the sale of these recovered metals. There is thus a clear need for EOL LIB recycling and a necessity to find out what is the best process technology available to recycle EOL LIBs. Traditionally LIBs have been recycled using pyrometallurgy, but the recent industry focus has shifted towards alternative process technologies such as hydrometallurgy. There is, however, no clear consensus on how these hydrometallurgical flowsheets should be arranged. As such, the purpose of this study was to compare the environmental impacts of implementing different hydrometallurgical process flowsheets designed for the recovery of metals from EOL LIBs. This comparative environmental study was performed using the life cycle assessment (LCA) framework and considered the use of three lixiviants (hydrochloric-, sulphuric-, and citric acid) alongside the use of three flowsheet options (sequential metal precipitation, mixed metal precipitation, and hybrid sequential precipitation - solvent extraction systems). Lastly, the process was modelled based on a mixed feed of LiCoO2, LiFePO4, and NMC111 batteries. The potential environmental impacts of mineral acid-based processes were found to generally be lower than that of organic acid-based processes by 18 to 61 percentage points. Furthermore, mixed metal precipitation provided the greatest environmental benefit of the flowsheet options considered by 46 to 117 percentage points when compared to the closest competitor. The LCA system was subsequently subjected to multivariate uncertainty analysis and a discernability analysis regarding process feed sensitivity which served to confirm the trends already observed. The LCA system was also subjected to a weak point analysis, where the consumption of NaOH and electricity were listed as the main concerns for process improvement. The process solutions recommended to address both weak points involve the integration of membrane technology and antisolvent crystallisation. Furthermore, the LCA system was compared for a South African and a European context, where it was determined that South Africa’s overreliance on hard coal for energy generation is the main difference between the two regions. Finally, the hydrometallurgical EOL LIB recycling processes were subjected to an additional LCA study regarding the use of recycled metals for resynthesizing NMC cathode materials. This additional study showed that integrating the sequential precipitation recycling process with solid-state synthesis of NMC622 cathode could save up to 70% on energy consumption during cathode synthesis. Meanwhile, integrating the mixed NMC precipitation recycling process with the solid-state synthesis of NMC622 cathode could reduce the environmental impact of NMC cathode production by up to 67%.en_ZA
dc.description.abstractAFRIKAANSE OPSOMMING:Litium-ioon batterye (LIB) het alledaags geword vir implementasie in verbruikerselektronika en het onlangs ook gewildheid verwerf vir gebruik in grootskaalse toepassings soos elektroniese voertuie. Die LIB mark is geprojekteer om te groei vanaf 700 GWh in 2022 na 4.7 TWh in 2030 (Fleischmann et al., 2023). Die gevolg van hierdie vining toenemende aanvrag na LIBs is die ontstaan van ‘n vining groeiende LIB afval stroom. Hierdie afval stroom sluit waardevolle metale soos litium, kobalt, nikkel, en mangaan in wat dan moontlik herwin kan word om voordele aan te bied soos afval vermindering en inkomste vanaf die verkope van die herwinde metale. Daar is dus ‘n groot aanvraag na die herwinning van afval LIBs en govolglik ‘n nood om uit te vind wat die beste beskikbare prosestegnologie is om afval LIBs te herwin. Tradisioneel is LIBs herwin deur pirometallurgie, maar onlangs het die industrie se fokus geskyf na alternatiewe prosestegnolgieë soos hidrometallurgie. Daar is egter geen duidelike konsensus oor hoe hierdie hidrometallurgiese prossese uitgelê moet word nie en as sulks was die doel van hierdie navorsing om ‘n vergelyking te doen van die omgewingsimpak wat ontstaan vanaf die implementasie van verskillende hidrometallurgiese prosesse vir die herwinning van metale vanaf afval LIBs. Hierdie vergelykende navorsing is voltooi aan hand van die lewenssiklus assesseringsraamwerk en het die gebruik evalueer van drie logingsmiddels (kloorsuur, swaelsuur, en sitroensuur) tesame met die gebruik van drie verskillende prosesuitlegte (opeenvolgende metaal presipitasie, gemengde metaal presipitasie, en ‘n geïntegreerde prosess van opeenvolgende presipitasie en organiese ekstraksie). Daarby is die proses gemodelleer gebasseer op ‘n gemengde voer van LiCoO2, LiFePO4, and NMC111 batterye. Die potensiële omgewingsimpak van die mineral suur-gebasseerde prosesse is oor die algemeen laer as die van die organiese suur-gebasseerde prossese met tussen 18 tot 61 persentasiepunte. Verder is dit gevind dat die gemengde metaal presipitasie process the grootste omgewingsvoordeel bydrae van al die prosesuitlegte met tussen 46 tot 117 persentasie punte wanneer dit vergelyk word met die naaste kompeteerder. Die resultate van die lewenssiklus assessering is gevolglik onderwerp an veelveranderlike onsekerheidsanalise en onderskeidbaarheidsanalise aangaande prosesvoer sensitiwiteit waarby dit ontdek was dat daar geen merkwaardige bewyse was om die resultate van die aanvanklike lewenssiklus assessering te ontken nie. Die lewenssiklus assessering sisteem is ook onderwerp aan swakpunt-analise, waar die verbruik van NaOH en elektrisiteit gelys is as the hoof ondernewmings vir prosesontwikkeling. Die prosesoplossings wat aanbeveel word for beide swakpunte betrek die integrasie van membraan-tegnologie en anti-oplosmiddel kristallisasie. Verder is die lewenssiklus assessering sisteem vergelyk vir die Suid-Afrikaanse en Europese kontekste, waarby dit vasgestel is dat Suid-Afrika se oorvertroue op steenkool vir kragopwekking die hoof verskil is in die prestasie van die herwinningsprosesse in die twee streke. Uiteindelik is die hidrometallurgiese herwinningsprosesse vir afval LIBs geïntegreer met ‘n bykomende lewenssiklus assessering wat gefokus het op die omgewingsimpak van herwinde metale gebruik vir die hersintese van NMC katode materiale. Die addisionele studie het bevind dat as die opeenvolgende presipitasie herwinningsproses geïntegreer word met die vaste-toestand sintese van NMC622 katode material dan kan daar tot en met 70% gespaar word op energieverbuik tydens die sintese van NMC katodes. Terselfde tyd kan die gemengde metaal presipitasie herwinningsproses die omgewingsimpak van NMC katode sintese met omtrent 67% verminder as dit geïntegreer word met die vaste-toestand sintese van NMC622 katode materiaal. en_ZA
dc.description.versionDoctoralen_ZA
dc.format.extentxxiv, 342 pages : illustrationsen_ZA
dc.identifier.urihttps://scholar.sun.ac.za/handle/10019.1/130324en_ZA
dc.language.isoen_ZAen_ZA
dc.language.isoen_ZAen_ZA
dc.publisherStellenbosch : Stellenbosch Universityen_ZA
dc.rights.holderStellenbosch Universityen_ZA
dc.subject.lcshLithium ion batteriesen_ZA
dc.subject.lcshHydrometallurgyen_ZA
dc.subject.lcshEnvironmental impact analysisen_ZA
dc.subject.lcshCircular economyen_ZA
dc.subject.lcshElectric vehicles -- Batteriesen_ZA
dc.titleComparing the environmental impact of different hydrometallurgical processes for the recycling of lithium-ion batteries using a life cycle assessment approachen_ZA
dc.typeThesisen_ZA
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