20.500.12556/RUL-130085 Nadomestitev litija, izgubljenega med začetnim delovanjem Li-ionskega akumulatorja Compensation of lithium, lost during the formation cycles in the Li-ion battery Upad kapacitete zaradi izgube litija v formacijskih ciklih delovanja je ena izmed težav litij ionskih akumulatorjev. Del litija iz katodnega materiala se porabi za pasivacijski sloj, ki se tvori na grafitni anodi. To vpliva na zmanjšanje kapacitete akumulatorja, kar poskušamo nadomestiti s predlitijacijo oziroma dodajanjem litija v celico. V sklopu diplomske naloge smo želeli eksperimentalno preveriti, če lahko z litijem bogata struktura litij manganovega oksifluorida (Li2MnO2F), pridobljenega z mehansko-kemijsko sintezo, v formacijskem ciklu delovanja akumulatorja predlitijira sistem. Za očiten prikaz predlitijacije je bil kot katodni material izbran TiO2, kjer vgradnja litija poteka v drugem potencialnem oknu kot pri spojini Li2MnO2F. Pripravili smo TiO2 elektrode in TiO2 elektrode z dodatkom Li2MnO2F ter jih galvanostatsko ciklali proti kovinskemu litiju oz. proti litiju in grafitu. Ugotovili smo, da se pri galvanostatskih meritvah z grafitno anodo ves litij iz žrtvovalne spojine Li2MnO2F porabi za nastanek pasivacijskega sloja. Zato ne pride do ciklanja katodnega materiala TiO2. To smo preverili tako, da smo h grafitni elektrodi dodali manjši kos kovinskega litija, in celoten sistem primerjali s sistemom, ki se je ciklal proti kovinskemu litiju. Tako smo pokazali, da je v primeru uporabe žrtvovalne spojine Li2MnO2F res zmanjkalo litija. Sklepamo lahko, da Li2MnO2F ne vsebuje dovolj litija za predlitijacijo celice. Z elektronskim vrstičnim mikroskopom (SEM) smo opravili analizo elektrod po končanih elektrokemijskih meritvah in pri tem ugotovili, da med galvanostatskim ciklanjem ni prišlo do degradacije katodnega materiala (Li2MnO2F). Capacity loss, which happens in formation cycles, is one of the problems of Li-ion batteries. A part of the lithium originally stored in the cathode material is used for the passivation layer, that is formed on the graphite anode. The formation of the SEI contributes to lower battery energy density. With the prelithiation or by adding lithium to the cell, capacity loss could be compensated. The aim of this bachelor’s thesis is to investigate whether the lithium rich compound lithium manganese oxyfluoride (Li2MnO2F), which is obtained by mechanochemical synthesis, has the ability to prelithiate the cell in the formation cycle. To clearly show the prelithiation process, TiO2 was selected as a cathode material. Electrodes containing TiO2 and electrodes with TiO2 / Li2MnO2F mixture were prepared and then cycled versus metal lithium, graphite electrode and versus graphite with lithium. It was found that during galvanostatic cycling versus graphite anode all the lithium from the sacrificial compound Li2MnO2F was used for passivation. Because of that, cycling of TiO2, that is part of the cathode material does not continue. This hypothesis was verified by adding a small piece of lithium to the graphite electrode. Results from cycling of the cathode material (Li2MnO2F and TiO2) versus metal lithium and versus graphite were then compared. This way, it was shown that when using the sacrificial compound Li2MnO2F, lithium is used for passivation and afterwards, no lithium is left for cycling. Thus, it can be argued that Li2MnO2F does not contain enough lithium to prelithiate the cell. After cycling, electrodes were analysed with scanning electron microscopy (SEM). It was observed that, while cycling, cathode material (Li2MnO2F) does not degrade. Litij-ionski akumulatorji predlitijacija irreverzibilna izguba kapacitete žrtvovalne spojine Li-ion battery prelithiation irreversible capacity loss sacrificial compounds true false false Slovenski jezik Angleški jezik Diplomsko delo/naloga 2021-09-10 09:00:00 2021-09-10 09:00:02 2022-09-09 04:14:44 0000-00-00 00:00:00 2021 0 0 0000-00-00 NiDoloceno NiDoloceno NiDoloceno 0000-00-00 0000-00-00 0000-00-00 13481 84666627 Novak_Doroteja_marija_-_Nadomestitev_litija,_izgubljenega_med_zacetnim_delovanjem_Li-ionskega_ak.pdf Novak_Doroteja_marija_-_Nadomestitev_litija,_izgubljenega_med_zacetnim_delovanjem_Li-ionskega_ak.pdf 1 3E17BB3128571C6E2F5CCBD9F029F2AF b95f16fc66952b8eb1775afe20c691be24b3ee1cdc0bb4d1d07e01e35d3b3229 7c111e56-1204-11ec-a523-00155dcfd717 https://repozitorij.uni-lj.si/Dokument.php?lang=slv&id=147142 Fakulteta za kemijo in kemijsko tehnologijo 0 0 0