Određivanje elektrokemijskih svojstava Li-polimer galvanskih članaka

master's thesis

• Title (english): Electrochemical characterization of Li-polymer batteries
• Author: Nikola Mihaljević
• Mentor: Zoran Mandić (mentor)
• Committee member: Zoran Mandić (predsjednik povjerenstva)
• Committee member: Helena Otmačić Ćurković (član povjerenstva)
• Committee member: Vladimir Dananić (član povjerenstva)
• Granter: University of Zagreb; Faculty of Chemical Engineering and Technology; Zagreb
• Defense date and country: 2021-09-23, Croatia
• Scientific / art field, discipline and subdiscipline: TECHNICAL SCIENCES; Chemical Engineering

Abstract

Elektrokemijska impedancijska spektroskopija i metoda diferencijalnog kapaciteta su korištene u ovom radu u svrhu istraživanja degradacijskih mehanizama litij-ionskih galvanskih članaka. Testiranja su provođena na odabranom litij-polimernom galvanskom članku (model Cellevia LP402030) nominalnog kapaciteta 190 mA h. Degradacija članka je provođena sukcesivnim punjenjem i pražnjenjem u rasponu napona 2,75 – 4,2 V kroz 300 ciklusa. Nakon svakih 50 ciklusa konstruiran je Ragoneov graf, snimljeni impedancijski spektri te snimljena krivulja ovisnosti diferencijalnog kapaciteta o naponu. Rezultati su pokazali da se opetovanim punjenjem i pražnjenjem galvanski članak degradira. Kao uzrok degradacije identificiran je nastanak i rast međusloja čvrstog elektrolita (SEI) u koji se ugrađuju litijevi ioni iz elektrolita te dovode do otežane difuzije litijevih iona iz elektrolita do elektrode i obrnuto.

Abstract (english)

Electrochemical impedance spectroscopy and differential capacity – incremental voltage (dc-iv) were used in this work for the identification of the degradation mechanisms of the li-ion batteries. The testings were carried out on the selected Li-polymer cell (model Cellevia LP402030) with capacity of 190 mA h. Degradation of the cell was performed by the successive charging/discharging through 300 cycles in the voltage range between 2,75 – 4,2 V. After each 50 cycles the cycling was stopped and the Ragone plot was constructed, impedance spectrum taken and the dc-iv curve recorded. The obtained results showed that charging/discharging process results in the degradation of the cell. The formation and the growth of the solid-electrolyte interphase (SEI) was identified as the main cause of the performance deterioration as a result of the incorporation of lithium ions in the SEI layer and hindered diffusion of lithium ions through it.

• Keywords: litij-polimerni galvanski članak; kapacitet; struja; potencijal; degradacija; elektrokemijska impedancijska spektroskopija; metoda diferencijalnog kapaciteta; SEI sloj; aktivni materijal
• Keywords (english): lithium polymer galvanic cell; capacitance; current; voltage; degradation; electrochemical impedance spectroscopy; differential capacitance method; SEI layer; active material
• Language: croatian
• URN:NBN: urn:nbn:hr:149:760557
• Study programme: Title: Applied Chemistry - Graduate study; specializations in: Environmental chemistry and green technologies, Advanced materials and technologies, Applied organic chemistry; Course: Environmental chemistry and green 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: 2023-04-14 12:31:01