Litij-polimer galvanski članci: elektrokemijska svojstva i degradacija

master's thesis

• Title (english): Li-polymer batteries: electrochemical properties and degradation
• Author: Ivan Petric
• Mentor: Zoran Mandić (mentor)
• Committee member: Zoran Mandić (predsjednik povjerenstva)
• Committee member: Vladimir Dananić (član povjerenstva)
• Committee member: Igor Sutlović (član povjerenstva)
• Granter: University of Zagreb; Faculty of Chemical Engineering and Technology; Zagreb
• Defense date and country: 2021-09-29, Croatia
• Scientific / art field, discipline and subdiscipline: TECHNICAL SCIENCES; Chemical Engineering

Abstract

U ovom radu testiran je litij-polimer galvanski članak, komercijalni članak LP402030 / 190 mAh. Za testiranje korištene su elektrokemijske metode. Stanje članka se određivalo na početku, kada je članak nov, te nakon degradacije. Također, pratilo se stanje napunjenosti (SoC) članka te stanje zdravlja (SoH). Glavni cilj rada je ukazati na karakteristike članka, ali i promjene tih karakteristika koje se javljaju zbog degradacije. Također, cilj je otkriti koji su uzroci degradacijskih procesa u članku. Elektrokemijske metode koje su korištene se elektrokemijska impedancijska spektroskopija, punjenje i pražnjenje članka konstantnom strujom, a iz toga konstrukcija Ragoneovih dijagrama te kulometrija visoke preciznosti. Sve tri metode su korištene na novoj bateriji te nakon prve degradacije, dok je elektrokemijska impedancijska spektroskopija korištena i nakon druge degradacije. Razlike u spektrima dobivenima elektrokemijskom impedancijskom spektroskopijom se vide u pomacima impedancijskih spektara, Ragoneovi dijagrami pokazuju da dolazi do smanjenja energija nakon degradacije, a kulometrija visoke preciznosti pokazuje da se kulonska učinkovitost smanjila nakon degradacije. Na kraju se impedancijski spektri modeliraju ekvivalentnim električnim krugom koji daju sličan odziv kao i eksperimentalni rezultati. Ekvivalentni krugovi najbolje opisuju fizikalno-kemijske procese koji se odvijaju u članku. Najčešći uzroci degradacije su formiranje SEI sloja te njegovo podebljanje, otpor difuziji iona te procesi povezani s kinetikom elektrona. Svi ti procesi su neizbježni. Stanje zdravlja članka pada s porastom stupnja degradacije, a s degradiranjem dolazi i do smanjenja životnog vijeka galvanskog članka.

Abstract (english)

In this work, a lithium-polymer galvanic cell, commercial cell LP402030 / 190 mAh, was tested. Electrochemical methods were used for the testing. The state of the cell was tested at the beginning, when the cell is previously unused, and after degradation. The state of charge (SoC) and the state of health (SoH) were also monitored. The main goal of the thesis was to identify the degradation processes which take place during continuous cycling of the cell. The electrochemical methods used were electrochemical impedance spectroscopy, charging and discharging of the cell with constant current, and from that the construction of Ragone plots and high precision coulometry. All three methods were used on the new, previously unused battery and after the first degradation, while electrochemical impedance spectroscopy was used after the second degradation. Differences in spectra obtained by electrochemical impedance spectroscopy were manifested as shifts of the impedance spectra on the x-axis, Ragone plot shows that there was a decrease in energy after degradation, and high-precision coulometry shows that Coulombic efficiency decreases after degradation. Finally, the impedance spectra were modeled by an equivalent electrical circuit that gave a similar response to the experimental results. The most common causes of degradation are the formation of the SEI layer and its thickening, ion diffusion resistance, and processes related to the kinetics of charge transfer. The state of health of the cell decreases with increasing degree of degradation, and with degradation there is a decrease in the lifespan of the galvanic cell.

• Keywords: litij-polimer galvanski članak; elektrokemijska impedancijska spektroskopija; Ragoneov dijagram; kulonska učinkovitost; stanje napunjenosti; degradacija; SEI sloj
• Keywords (english): lithium-polymer galvanic cell; electrochemical impedance spectroscopy; Ragone plot; Coulombic efficiency; state of charge; degradation; SEI layer
• Language: croatian
• URN:NBN: urn:nbn:hr:149:230196
• 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: magistar/magistra primijenjene kemije (magistar/magistra primijenjene kemije)
• Type of resource: Text
• File origin: Born digital
• Access conditions: Access restricted to students and staff of home institution
• Created on: 2023-04-20 13:27:25