Mikrokapsule v litij-ionskih akumulatorjih za samoobnavljanje kapacitete

Zakrajšek, Žan (author), Dominko, Robert (mentor)

Življenjska doba in uporabnost litij-ionskih akumulatorjev se izboljšuje, kljub temu pa se razvijajo nove možnosti, kako še dodatno podaljšati njihovo delovanje. Ena izmed možnosti je izboljšava medfaznih površin, lahko pa v akumulatorje uvedemo dodatke, ki se aktivirajo z zunanjo aktivacijo. V diplomskem delu smo uporabili mikrokapsule, v katere smo shranili litijevo sol litijev skvarat, ki je ob aktivaciji razpadel na litijeve katione in preostanek. Tako pridobljeni litijevi kationi omogočijo višjo kapaciteto akumulatorja, ki se je znižala zaradi degradacijskih procesov, v katerih se porabljajo litijevi kationi. Kapsule smo vgradili v katodni kompozit na osnovi litij-železovega fosfata (LFP). Kot anoda je bila uporabljena grafitna elektroda. Uporabljena litijeva sol je razpadla pri napetosti 3,7 V, kar je višje, kot je napetost, ki omejuje delovanje uporabljene kombinacije materialov v akumulatorju. Hipotezo, da lahko s pomočjo mikrokapsul nadomestimo izgubljeno kapaciteto z aktivacijo pri napetosti 4,0 V, smo preverili s pomočjo kontrolnega eksperimenta, kjer je bil litijev skvarat brez zaščite v mikrokapsulah in z akumulatorjem, ki ni vseboval dodane soli. Na koncu smo tudi kvantificirali, koliko od dodane soli se je aktivno vključilo v obnovitev kapacitete akumulatorja.

• Language: Slovenian
• Keywords: mikrokapsule, litijev skvarat, LFP, ciklična voltametrija, galvanostatsko ciklično merjenje z omejitvijo potenciala
• Work type: Bachelor thesis/paper
• Typology: 2.11 - Undergraduate Thesis
• Organization: FKKT - Faculty of Chemistry and Chemical Technology
• Year: 2025
• PID: 20.500.12556/RUL-177214
• COBISS.SI-ID: 264999939
• Publication date in RUL: 17.12.2025

Secondary language

• Language: English
• Title: Microcapsules in lithium-ion batteries for capacity self-restoration

Abstract

Lithium-ion batteries are improving in lifespan and usability, but new methods are being developed to extend battery life even further. One approach is to enhance the interfacial surfaces or introduce additives into the batteries that are activated by external triggers. We used microcapsules containing a lithium salt lithium squarate that, when activated, decomposed into lithium cations and a residue. The resulting lithium cations enable higher battery capacity, compensating for losses due to degradation processes that consume lithium cations. The capsules were embedded in a lithium iron phosphate (LFP) based cathode composite, and a graphite electrode served as the anode. The lithium salt used decomposed at a voltage of 3.7 V, which is higher than the voltage that limits the performance of the material combination used in the battery. We tested the hypothesis that microcapsules can restore lost capacity by activation at 4.0 V using a control experiment with unencapsulated lithium squarate and a battery containing no added salt. Finally, we quantified how much of the added salt actively contributed to the battery’s capacity recovery.

• Keywords: microcapsules, lithium squarate, LFP, cyclic voltammetry, galvanostatic cycling with potential limitation