Usporedba kombinacije Ni-Mn-Co oksida i litijevog ferofosfata kao katodnih materijala za litij ionske galvanske članke

master's thesis

• Title (english): The comparison of the combination of Ni-Mn-Co oxides with lithium iron phosphate as cathodic materials for lithium-ion batteries
• Author: Zoran Povijač
• Mentor: Zoran Mandić (mentor)
• Committee member: Marijana Kraljić Roković (predsjednik povjerenstva)
• Committee member: Petar Kassal (član povjerenstva)
• Committee member: Vladimir Dananić (član povjerenstva)
• Granter: University of Zagreb; Faculty of Chemical Engineering and Technology; Zagreb
• Defense date and country: 2024-09-26, Croatia
• Scientific / art field, discipline and subdiscipline: NATURAL SCIENCES; Chemistry

Abstract

Svrha ovog rada je bila pripraviti elektrode od nikal-mangan-kobalt oksida i litijevog ferofosfata te ih testirati kao pozitivne elektrode u litij ionskim galvanskim člancima. Elektrode su dobivene prevlačenjem paste na strujni kolektor od aluminijske folije. Pasta se sastoji od aktivnog materijala, veziva i aditiva. Litij ionski galvanski članci su priređeni u komercijalnoj El-Cell ćeliji. Elektrokemijska mjerenja su provedena u dvo-elektrodnom i tro-elektrodnom sustavu metodom punjenja/pražnjenja članka te cikličkom voltametrijom i elektrokemijskom impedancijskom spektroskopijom u dvo-elektrodnom sustavu. Za određivanje veličine čestica je korišteno dinamičko raspršenje svjetlosti dok se FTIR koristio za detekciju mogućih onečišćenja. Ciklička voltametrija upućuje na dvofaznu reakciju interkalacije kod LFP materijala te stupnjevitu elektrokemijsku reakciju kod NMC materijala. NMC materijal potencijalno postiže veću snagu zbog reakcija pri višim potencijalima. Ciklički voltamogram LFP-a pokazuje jedan elektroaktivan redoks (Fe2+/Fe3+) dok NMC ukazuje na dva para sa različitim stupnjem oksidacije (Ni2+/Ni4+ i Co3+/Co4+). Naponski profil LFP pozitivne elektrode je plato karakterističan za dvofaznu reakciju (de)interkalacije dok je naponski profil NMC elektrode u konstantnom padu. NMC postiže više specifične kapacitete punjenja i pražnjenja, no posjeduje slabiju retenciju kapaciteta na većim strujama punjenja/pražnjenja od LFP pozitivne elektrode. Na oba materijala je vidljiv gubitak kapaciteta u prvom ciklusu punjenja zbog SEI sloja, no izraženiji je kod NMC. Elektrokemijska impedancijska spektroskopija ukazuje na bolju elektronsku i ionsku vodljivost NMC materijala. Dinamičko raspršenje svjetlosti pokazuje bolju uniformnost i optimalniju veličinu čestica kod NMC materijala. Na FTIR spektrima se vidi slabi signal mogućeg sadržaja molekula vode na NMC prahu.

Abstract (english)

The purpose of this work was to prepare electrodes from nickel-manganese-cobalt oxide and lithium ferrophosphate and test them as positive electrodes in lithium-ion galvanic cells.
The electrodes were obtained by applying the paste to the aluminum foil current collector. The paste consists of active material, binders and additives. Lithium-ion galvanic cells were prepared in a commercial El-Cell cell. Electrochemical measurements were carried out in a two-electrode and three-electrode system using the cell charging/discharging method and cyclic voltammetry and electrochemical impedance spectroscopy in a two-electrode system. Dynamic light scattering was used to determine particle size, while FTIR was used to detect possible contaminants. Cyclic voltammetry points to a two-phase intercalation reaction in LFP materials and a stepwise electrochemical reaction in NMC materials. NMC material potentially achieves higher power due to reactions at higher potentials. The cyclic voltammogram of LFP shows one electroactive redox (Fe2+/Fe3+), while NMC indicates two couples with different degrees of oxidation (Ni2+/Ni4+ and Co3+/Co4+). The voltage profile of the LFP positive electrode is a plateau characteristic of a twophase (de)intercalation reaction, while the voltage profile of the NMC electrode is in constant decline. NMC achieves higher specific charge and discharge capacities but has weaker capacity retention at higher charge/discharge currents than the LFP positive electrode. Both materials show a loss of capacity in the first charging cycle due to the SEI layer formation, but it is more pronounced in NMC. Electrochemical impedance spectroscopy indicates better electronic and ionic conductivity of NMC material. Dynamic light scattering shows better uniformity and optimal particle size for NMC materials. The FTIR spectra show a weak signal of the possible content of water molecules on the NMC powder.

• Keywords: litij ionski galvanski članak; nikal-mangan-kobalt oksid; litijev ferofosfat; interkalacija
• Keywords (english): Li-ion batteries; nickel-manganese-cobalt oxide; lithium ferrophosphate; intercalation
• Language: croatian
• URN:NBN: urn:nbn:hr:149:566415
• Study programme: Title: Applied Chemistry - Graduate study; specializations in: Environmental chemistry and green technologies, Advanced materials and technologies, Applied organic chemistry; Course: Advanced materials and technologies; Study programme type: university; Study level: graduate; Academic / professional title: sveučilišni/a magistar/magistra primijenjene kemije (sveučilišni/a magistar/magistra primijenjene kemije)
• Type of resource: Text
• File origin: Born digital
• Access conditions: Open access
• Created on: 2024-11-07 08:58:44