search query: @keyword lithium-ion battery / total: 9
results-list
reference: 7 / 9
« previous | next »
Author:Jalkanen, Kirsi
Title:Vertailuelektrodin käyttö litiumioniakkututkimuksessa
The use of reference electrodes in lithium-ion battery research
Publication type:Master's thesis
Publication year:2010
Pages:vi + 109 s. + liitt. 11      Language:   fin
Department/School:Kemian laitos
Main subject:Fysikaalinen kemia   (Kem-31)
Supervisor:Kallio, Tanja
Instructor:Vuorilehto, Kai
OEVS:
Electronic archive copy is available via Aalto Thesis Database.
Instructions
close

Reading digital theses in the closed network of the Aalto University Harald Herlin Learning Centre

In the closed network of Learning Centre you can read digital and digitized theses not available in the open network.

The Learning Centre contact details and opening hours: https://learningcentre.aalto.fi/en/harald-herlin-learning-centre/

You can read theses on the Learning Centre customer computers, which are available on all floors.

Logging on to the customer computers

  • Aalto University staff members log on to the customer computer using the Aalto username and password.
  • Other customers log on using a shared username and password.

Opening a thesis

  • On the desktop of the customer computers, you will find an icon titled:

    Aalto Thesis Database

  • Click on the icon to search for and open the thesis you are looking for from Aaltodoc database. You can find the thesis file by clicking the link on the OEV or OEVS field.

Reading the thesis

  • You can either print the thesis or read it on the customer computer screen.
  • You cannot save the thesis file on a flash drive or email it.
  • You cannot copy text or images from the file.
  • You cannot edit the file.

Printing the thesis

  • You can print the thesis for your personal study or research use.
  • Aalto University students and staff members may print black-and-white prints on the PrintingPoint devices when using the computer with personal Aalto username and password. Color printing is possible using the printer u90203-psc3, which is located near the customer service. Color printing is subject to a charge to Aalto University students and staff members.
  • Other customers can use the printer u90203-psc3. All printing is subject to a charge to non-University members.
Location:P1 Ark Aalto  3522   | Archive
Keywords:lithium-ion battery
lithium reference electrode
litiumioniakku
litiumvertailuelektrodi
Abstract (eng): For lithium-ion batteries to become common in large applications the technology must be improved.
Electrode materials are the key to this and to accurately characterize their impact on the cell performance, a reference electrode should be used in the study.
By employing a reference electrode the cell voltage and impedance can be divided in the contributions of the individual electrodes.
Metallic lithium is widely used as reference electrode in lithium-ion battery studies.

In this thesis a lithium reference electrode was placed into large-format, commercial lithium iron phosphate (LFP) / graphite cells.
For characterizing the electrode materials, small reference electrode cells were assembled as well.
Small cells consisted of either both electrode materials or only one of the materials as working electrode and Lithium as counter electrode.
The cells also included a lithium reference electrode.
Charging and discharging, that is cycling the cells and impedance spectroscopy was used as research methods.
Except for the small graphite cells, all cells assembled showed good performance and were stable during cycling.
The instability of the graphite cells was probably caused by the decreasing graphite electrode active area due to drying of the separator.
The results improved when a thick separator able to soak up more electrolytes was used.
In the small cells, the lithium counter electrode potential did not remain constant during cycling.
In addition, its impedance varied and was in some of the cells considerably high.
These problems related to the Lithium counter electrode were shown to be solved by employing a reference electrode in the measurements.

The study conducted provided information on problems noticed in the performance of large-format cells.
The impact of improvements in the LFP material was also demonstrated.
The same phenomena were observed both with reference electrode measurements on large-format cells and with small cells assembled from LFP materials.
Small LFP/graphite cells were used to demonstrate how the LFP/graphite ratio affects the cell behaviour.
Measurements on graphite cells showed the typical potential plateaus of graphite electrodes and passivation of the graphite surface was also observed.
Abstract (fin): Litiumioniakkujen yleistyminen suurissa sovelluskohteissa vaatii teknologian kehittämistä, jossa tärkeässä asemassa ovat kennojen elektrodimateriaalit.
Jotta elektrodimateriaalien vaikutusta kennojen toimintaan voidaan karakterisoida tarkasti, täytyy tutkimuksissa käyttää vertailuelektrodia.
Sen avulla on mahdollista jakaa kennojännite ja kennon impedanssi eri elektrodien osuuksiin.
Vertailuelektrodina on litiumioniakkututkimuksessa yleisesti käytetty metallista litiumia.

Työssä lisättiin litiumvertailuelektrodi isoihin litiumrautafosfaatti (LFP)-grafiittikennoihin.
LFP- ja grafiittimateriaalien erillistä karakterisointia varten koottiin myös pieniä vertailuelektrodikennoja.
Pienissä kennoissa oli joko vain toista materiaaleista tutkittavana elektrodina ja litiumia vastaelektrodina tai molempia elektrodimateriaaleja.
Lisäksi kennoissa oli vertailuelektrodi.
Tutkimusmenetelminä käytettiin kennojen latausta ja purkua eli syklausta sekä impedanssispektroskopiaa.
Pieniä grafiittikennoja lukuun ottamatta kaikki työssä tutkitut kennot toimivat hyvin ja olivat syklaustesteissä stabiileja.
Grafiittikennojen epästabiilius johtui luultavasti elektrodien aktiivisten pinta-alojen pienenemisestä separaattorin kuivumisen vuoksi, sillä tulokset paranivat käytettäessä enemmän elektrolyyttiä imevää, paksua separaattoria.
Pienten kennojen litiumvastaelektrodin potentiaali ei pysynyt syklauksessa vakiona.
Lisäksi elektrodin impedanssi vaihteli ja oli osassa kennoista merkittävän suuri.
Nämä litiumvastaelektrodiin liittyvät ongelmat voitiin ratkaista käyttämällä mittauksissa vertailuelektrodia.

Tehdyn tutkimuksen avulla pystyttiin analysoimaan isojen kennojen suorituskyvyssä havaittuja ongelmia ja materiaalikehityksen vaikutusta niihin.
Samat ilmiöt nähtiin sekä isoilla kennoilla vertailuelektrodin avulla tehdyistä mittauksista että LFP-materiaalista kootuilla pienillä kennoilla.
Pienillä LFP-grafiittikennoilla voitiin tutkia kennon tasapainotuksen eli LFP/grafiitti -suhteen vaikutusta kennon toimintaan.
Grafiittikennoilla tehdyistä mittauksista nähtiin grafiittielektrodille tyypilliset lataus- ja purkukäyrien potentiaalitasanteet sekä grafiittipinnan passivoituminen.
ED:2010-11-29
INSSI record number: 41384
+ add basket
« previous | next »
INSSI