Methods of Studying Electrocatalysts in Polymer Electrolyte Membrane Cells

Olli Sorsa

Methods of Studying Electrocatalysts in Polymer Electrolyte Membrane Cells

Julkaisun otsikon käännös: Elektrokatalyyttien tutkimusmenetelmät polymeerielektrolyyttimembraanikennoissa

Olli Sorsa

Tutkimustuotos: Doctoral Thesis › Collection of Articles

Abstrakti

Joustavien energian varastointimenetelmien tarve lisääntyy, kun siirrymme kohti uusiutuvaa energiantuotantoa. Polymeerielektrolyyttimembraanikenno (PEM) teknologiat mahdollistavat helposti skaalattavia laitteita, joissa sähköenergia voidaan varastoida vedyksi vettä hajottamalla. Tarvittaessa vety voidaan muuntaa takaisin sähköenergiaksi korkealla hyötysuhteella. PEM-teknologioiden käyttö ei ole vielä yleistynyt, koska niiden komponentit ovat kalliita ja osa komponenteista huonosti kestäviä. Siksi näiden teknologioiden kehityksessä tarvitaan materiaalien perustutkimusta. Erityisesti elektrokatalyyttien tutkimus on tärkeää, sillä vain kriittisiksi raaka-aineiksi luokiteltuja platinametalleja käytetään kaupallisten sovellusten katalyytteinä. Tämä työ keskittyy kahteen tällä hetkellä kaupallisesti kannattavimpaan PEM-kenno tyyppiin: veden PEM-elektrolyyseriin ja PEM-polttokennoon. Työssä esitellään uusia vaihtoehtoja elektrokatalyyteiksi, joilla voitaisiin vähentää kriittisten raaka-aineiden tarvetta näissä laiteissa ja parantaa niiden kestävyyttä. Elektrokatalyyttien kokeellista tutkimusta voidaan suorittaa kahdessa eri kennotyypissä: puolikennossa ja kokokennossa. Puolikennossa tehtävät kokeet ovat hyödyllisiä katalyyttimateriaalien seulonnassa, mutta katalyytin kaupallistaminen vaatii laajoja kokokennomittauksia. Koska kokokennomittauksissa käytetään hyvin erilaisia mittausohjelmia ja koska niiden teoreettista taustaa ei aina tunneta täysin, tämä väitöskirja käy läpi erilaisia elektrokatalyyttien mittaustekniikoita kokokennosysteemeissä. Työssä painotetaan kokokennojen kestävyyskokeita ja häviömekanismien tarkastelua sähkökemiallisen impedanssispektroskopian avulla. Kokokennomittauksissa sekä anodi että katodi vaikuttavat koko kennon suorituskykyyn. Jotta niiden vaikutukset voidaan erottaa, tarvitaan referenssielektrodi. Tässä työssä esitellään uusi PEM-elektrolyyserille tarkoitettu referenssielektrodi ja sitä hyödynnetään kaupallisten anodi- ja katodikatalyyttimateriaalien kestävyyden tutkimiseen. Katodikatalyytissä havaittiin platinananopartikkeleiden nopeaa kasvua ja hiilikantajan korroosiota. Sen korvaajaksi ehdotetaan hiilinanoputkia kantajana käyttävää katalyyttiä, jonka rakenteen havaittiin hajoavan selvästi hitaammin näillä mekanismeilla. PEM-polttokennon katodikatalyytin nanopartikkeleiden nopean kasvun ratkaisuksi ehdotetaan mesohuokoista kalvomaista platinakatalyyttiä. Sen katalyyttinen aktiivisuus heikkeneekin huomattavasti kaupallista katalyyttiä hitaammin, ja sen aktiivisuutta saatiin nostettua entisestään käyttämällä platinan ja koboltin seosta. Katalyyttitutkimuksen kannalta on olennaista ymmärtää, mitä katalyytille tapahtuu kennon ollessa päällä. Tässä työssä esitetyillä menetelmillä on mahdollista syventää sitä ymmärrystä, jotta voidaan kehittää nykyisiä katalyyttejä ja suunnitella seuraavan sukupolven katalyyttejä.

Julkaisun otsikon käännös	Elektrokatalyyttien tutkimusmenetelmät polymeerielektrolyyttimembraanikennoissa
Alkuperäiskieli	Englanti
Pätevyys	Tohtorintutkinto
Myöntävä instituutio	Aalto-yliopisto
Valvoja/neuvonantaja	Kallio, Tanja, Vastuuprofessori Kanninen, Petri, Ohjaaja
Kustantaja	Aalto University
Painoksen ISBN	978-952-64-0018-1
Sähköinen ISBN	978-952-64-0019-8
Tila	Julkaistu - 2020
OKM-julkaisutyyppi	G5 Artikkeliväitöskirja

Tutkimusalat

polymeerielektrolyyttimembraani
polttokenno
elektrolyyseri
sähkökemiallinen impedanssispektroskopia
katalyyttien kestävyys

YK:n kestävän kehityksen tavoitteet

Tämä tuotos edistää seuraavia kestävän kehityksen tavoitteita:

Pääsy asiakirjaan

http://urn.fi/URN:ISBN:978-952-64-0019-8

OtaNano
Rissanen, A. (Manager)
Aalto-yliopisto
Laitteistot/tilat: Facility
OtaNano – Kylmälaboratorio
Savin, A. (Manager) & Rissanen, A. (Other)
OtaNano
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OtaNano Nanomikroskopiakeskus
Seitsonen, J. (Manager) & Rissanen, A. (Other)
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@phdthesis{6c88cdc3b1904013922a5a03706ebe5f,

title = "Methods of Studying Electrocatalysts in Polymer Electrolyte Membrane Cells",

abstract = "The demand for flexible energy storage solutions increases as we gradually shift towards the utilization of renewable energy sources. Polymer electrolyte membrane (PEM) cell technologies provide easily scalable devices that can store energy through water splitting as hydrogen and, if necessary, restore the energy with high efficiency. The PEM technologies have not yet generalized due to the high cost and partially non-durable cell components. Thus, fundamental material research is needed for the development of these technologies. The development of electrocatalysts is particularly urgent, as none other than critical raw material categorized platinum group metals have been extensively used in PEM cells. This thesis focuses on the two currently most commercially viable PEM cell types: PEM water electrolyser and PEM fuel cell. Novel electrocatalyst material solutions are presented with the aim of reducing the amount of required critical raw materials and to increase the durability of these devices. The experimental material research of electrocatalysts takes place in two types of systems: half-cell and full-cell systems. Half-cell experiments are useful for catalyst material screening, but for commercialization, extensive full-cell tests are required. Since the protocols of full-cell experiments have high variation and since their theoretical background is not always fully understood, this thesis reviews the different experimental full-cell methods used for electrocatalysts. Emphasis is applied to durability experiments and the analysis of electrochemical impedance spectroscopy to understand loss mechanisms in these cells. In full-cell experiments, both the anode and cathode influence the performance of the full cell. In order to separate their impact, a reference electrode is required. In this thesis, a novel reference electrode design is presented for PEM water electrolyser and it is used to study the degradation of the state-of-the-art anode and cathode in a long-term experiment. A rapid platinum nanoparticle growth and corrosion of the carbon support were detected in the cathode catalyst. A novel catalyst utilizing carbon nanotubes as the support material is proposed and verified to have a significantly lower rate for these degradation mechanisms. In the PEM fuel cell, a novel mesoporous film catalyst is proposed to solve the fast growth of nanoparticles on the cathode. The novel catalyst indeed has a low degradation rate in comparison to the state-of-the-art catalyst. The mass activity of mesoporous platinum can be increased further by alloying with cobalt. The understanding of what catalyst experiences during full-cell operation is essential for catalyst development. Using the methods provided in this thesis, it is possible to enhance that understanding to improve the existing catalysts and help to design the next generations.",

keywords = "polymer electrolyte membrane, fuel cell, water electrolyser, electrochemical impedance spectroscopy, catalyst degradation, polymeerielektrolyyttimembraani, polttokenno, elektrolyyseri, s{\"a}hk{\"o}kemiallinen impedanssispektroskopia, katalyyttien kest{\"a}vyys, polymer electrolyte membrane, fuel cell, water electrolyser, electrochemical impedance spectroscopy, catalyst degradation",

author = "Olli Sorsa",

year = "2020",

language = "English",

isbn = "978-952-64-0018-1",

series = "Aalto University publication series DOCTORAL DISSERTATIONS",

publisher = "Aalto University",

number = "131",

address = "Finland",

school = "Aalto University",

}

TY - BOOK

T1 - Methods of Studying Electrocatalysts in Polymer Electrolyte Membrane Cells

AU - Sorsa, Olli

PY - 2020

Y1 - 2020

N2 - The demand for flexible energy storage solutions increases as we gradually shift towards the utilization of renewable energy sources. Polymer electrolyte membrane (PEM) cell technologies provide easily scalable devices that can store energy through water splitting as hydrogen and, if necessary, restore the energy with high efficiency. The PEM technologies have not yet generalized due to the high cost and partially non-durable cell components. Thus, fundamental material research is needed for the development of these technologies. The development of electrocatalysts is particularly urgent, as none other than critical raw material categorized platinum group metals have been extensively used in PEM cells. This thesis focuses on the two currently most commercially viable PEM cell types: PEM water electrolyser and PEM fuel cell. Novel electrocatalyst material solutions are presented with the aim of reducing the amount of required critical raw materials and to increase the durability of these devices. The experimental material research of electrocatalysts takes place in two types of systems: half-cell and full-cell systems. Half-cell experiments are useful for catalyst material screening, but for commercialization, extensive full-cell tests are required. Since the protocols of full-cell experiments have high variation and since their theoretical background is not always fully understood, this thesis reviews the different experimental full-cell methods used for electrocatalysts. Emphasis is applied to durability experiments and the analysis of electrochemical impedance spectroscopy to understand loss mechanisms in these cells. In full-cell experiments, both the anode and cathode influence the performance of the full cell. In order to separate their impact, a reference electrode is required. In this thesis, a novel reference electrode design is presented for PEM water electrolyser and it is used to study the degradation of the state-of-the-art anode and cathode in a long-term experiment. A rapid platinum nanoparticle growth and corrosion of the carbon support were detected in the cathode catalyst. A novel catalyst utilizing carbon nanotubes as the support material is proposed and verified to have a significantly lower rate for these degradation mechanisms. In the PEM fuel cell, a novel mesoporous film catalyst is proposed to solve the fast growth of nanoparticles on the cathode. The novel catalyst indeed has a low degradation rate in comparison to the state-of-the-art catalyst. The mass activity of mesoporous platinum can be increased further by alloying with cobalt. The understanding of what catalyst experiences during full-cell operation is essential for catalyst development. Using the methods provided in this thesis, it is possible to enhance that understanding to improve the existing catalysts and help to design the next generations.

AB - The demand for flexible energy storage solutions increases as we gradually shift towards the utilization of renewable energy sources. Polymer electrolyte membrane (PEM) cell technologies provide easily scalable devices that can store energy through water splitting as hydrogen and, if necessary, restore the energy with high efficiency. The PEM technologies have not yet generalized due to the high cost and partially non-durable cell components. Thus, fundamental material research is needed for the development of these technologies. The development of electrocatalysts is particularly urgent, as none other than critical raw material categorized platinum group metals have been extensively used in PEM cells. This thesis focuses on the two currently most commercially viable PEM cell types: PEM water electrolyser and PEM fuel cell. Novel electrocatalyst material solutions are presented with the aim of reducing the amount of required critical raw materials and to increase the durability of these devices. The experimental material research of electrocatalysts takes place in two types of systems: half-cell and full-cell systems. Half-cell experiments are useful for catalyst material screening, but for commercialization, extensive full-cell tests are required. Since the protocols of full-cell experiments have high variation and since their theoretical background is not always fully understood, this thesis reviews the different experimental full-cell methods used for electrocatalysts. Emphasis is applied to durability experiments and the analysis of electrochemical impedance spectroscopy to understand loss mechanisms in these cells. In full-cell experiments, both the anode and cathode influence the performance of the full cell. In order to separate their impact, a reference electrode is required. In this thesis, a novel reference electrode design is presented for PEM water electrolyser and it is used to study the degradation of the state-of-the-art anode and cathode in a long-term experiment. A rapid platinum nanoparticle growth and corrosion of the carbon support were detected in the cathode catalyst. A novel catalyst utilizing carbon nanotubes as the support material is proposed and verified to have a significantly lower rate for these degradation mechanisms. In the PEM fuel cell, a novel mesoporous film catalyst is proposed to solve the fast growth of nanoparticles on the cathode. The novel catalyst indeed has a low degradation rate in comparison to the state-of-the-art catalyst. The mass activity of mesoporous platinum can be increased further by alloying with cobalt. The understanding of what catalyst experiences during full-cell operation is essential for catalyst development. Using the methods provided in this thesis, it is possible to enhance that understanding to improve the existing catalysts and help to design the next generations.

KW - polymer electrolyte membrane

KW - fuel cell

KW - water electrolyser

KW - electrochemical impedance spectroscopy

KW - catalyst degradation

KW - polymeerielektrolyyttimembraani

KW - polttokenno

KW - elektrolyyseri

KW - sähkökemiallinen impedanssispektroskopia

KW - katalyyttien kestävyys

KW - polymer electrolyte membrane

KW - fuel cell

KW - water electrolyser

KW - electrochemical impedance spectroscopy

KW - catalyst degradation

M3 - Doctoral Thesis

SN - 978-952-64-0018-1

T3 - Aalto University publication series DOCTORAL DISSERTATIONS

PB - Aalto University

ER -

Methods of Studying Electrocatalysts in Polymer Electrolyte Membrane Cells

Abstrakti

Tutkimusalat

YK:n kestävän kehityksen tavoitteet

Pääsy asiakirjaan

Sormenjälki

Laitteet

OtaNano

OtaNano – Kylmälaboratorio

OtaNano Nanomikroskopiakeskus

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