Negative Electrode Materials for Lithium Ion Batteries

Elina Pohjalainen

Negative Electrode Materials for Lithium Ion Batteries

Julkaisun otsikon käännös: Litium-ioniakkujen negatiivielektrodimateriaalit

Elina Pohjalainen

Kemian ja materiaalitieteen laitos

Tutkimustuotos: Doctoral Thesis › Collection of Articles

Abstrakti

Litium-ioniakut ovat nykyään yleisin akkutyyppi kannettavissa laitteissa, ja niiden käyttö yleistyy myös suuremman mittakaavan sovelluksissa. Lukuisia erilaisia elektrodimateriaaleja on tutkittu litium-ioniakuille, joista monet ovat myös jo kaupallisessa käytössä. Elektrodi-materiaalit ja kennon muut ominaisuudet vaikuttavat suuresti akun ominaisuuksiin, hintaan ja turvallisuuteen. Tämän väitöskirjatyön painopiste on negatiivielektrodimateriaaleissa ja elektrodien valmistusmenetelmissä, jotka ovat ympäristöystävällisiä ja turvallisia suuren mittakaavan sovelluksiin. Työn ensimmäinen osa käsittelee litiumtitanaattia, Li4Ti5O12 (LTO), negatiivielektrodi-materiaalina, ja erityisesti partikkelin morfologian vaikutusta materiaalin sähkökemialliseen käyttäytymiseen. Työssä verrataan kahta LTO-materiaalia, joilla on sama kiderakenne, mutta erilainen morfologia, ja osoitetaan, että pieni partikkelikoko ja suuri pinta-ala tuottavat parempia tuloksia akussa. Lisäksi litiumin (de)insertiopotentiaalin ja litiumin varastoinnin havaitaan olevan erilaista partikkelin pinnalla kuin partikkelin sisäosissa. Tulokset osoittavat, että LTO:n ominaisuuksiin voidaan vaikuttaa muuttamalla partikkelien morfologiaa. Lisäksi tutkittiin johtavuushiilen vaikutusta LTO-elektrodien toimintaan. Kun LTO-elektrodeja mitattiin pienillä virrantiheyksillä huoneen lämpötilassa, johtavuushiilen vaikutus oli vähäinen. Kuitenkin vaativammissa olosuhteissa (korkeilla virrantiheyksillä ja matalissa lämpötiloissa) havaitaan johtavuushiilen hyödyllinen vaikutus erityisesti pienemmällä LTO:n partikkelikoolla. Johtopäätöksenä todetaan, että johtavuushiilen vaikutus LTO-elektrodien toimintaan riippuu niin LTO-partikkelien kuin elektrodin morfologiasta. Työn toisessa osassa tutkitaan vesiliukoisen akrylaattisideaineen (Acryl S020) käyttöä LTO- ja grafiittielektrodien vesipohjaisessa valmistuksessa. Yleisesti käytetty PVDF (polyvinyyli-deenifluoridi) -sideaine on kallista ja tarvitsee liuottimeksi haitallisen NMP:n (N-metyyli-pyrrolidoni), ja tämän vuoksi vaihtoehtoisia materiaaleja on tutkittu paljon. Työssä näytetään, että LTO-elektrodeilla, jotka on valmistettu Acryl S020 -sideaineella, saavutetaan samanlaiset kapasiteetit kuin perinteisillä PVDF-sideaineeseen pohjautuvilla LTO-elektrodeilla. Lisäksi elektrodien valmistusta testattiin pilot-skaalan slot die ja gravuuripainatus -menetelmillä, joilla molemmilla saavutettiin tasaiset kapasiteetit yli 500 syklin ajan. LTO:n veden absorption/desorption mitattiin olevan reversiibeliä, joten vesipohjainen prosessi vaikuttaa mahdolliselta myös LTO-elektrodien valmistukseen. Lupaavia tuloksia saatiin myös Acryl S020 -sideaineella grafiittielektrodeissa, joilla mitattiin korkeammat kapasiteetit suurilla sähkövirroilla ja matalissa lämpötiloissa verrattuna grafiittielektrodeihin, jotka oli valmistettu CMC (karboksimetyyliselluloosa) ja SBR (styreenibutadieenikumi) sideaineyhdistelmällä.

Julkaisun otsikon käännös	Litium-ioniakkujen negatiivielektrodimateriaalit
Alkuperäiskieli	Englanti
Pätevyys	Tohtorintutkinto
Myöntävä instituutio	Aalto-yliopisto
Valvoja/neuvonantaja	Kallio, Tanja, Vastuuprofessori
Kustantaja	Aalto University
Painoksen ISBN	978-952-60-6820-6
Sähköinen ISBN	978-952-60-6821-3
Tila	Julkaistu - 2016
OKM-julkaisutyyppi	G5 Artikkeliväitöskirja

Tutkimusalat

litium-ioniakut
negatiivielektrodit
elektrodien valmistusmenetelmät

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@phdthesis{c2b304dc2e01467f871a0a28b1a1224b,

title = "Negative Electrode Materials for Lithium Ion Batteries",

abstract = "Lithium ion batteries have become the primary energy source for portable electronics, and their utilization in larger scale applications is increasing as well. Numerous electrode materials have been investigated for lithium ion batteries and several different materials are also found in commercial cells. The properties, cost and safety of the battery strongly depends on the selected electrode materials and cell design. The focus of this thesis is on negative electrode materials and electrode manufacturing methods that are environmentally friendly and safe for large scale and high power applications. First part of this thesis studies Li4Ti5O12 (LTO) as a negative electrode material. Especially the effect of the particle morphology on the electrochemical performance is evaluated in detail. It is shown by comparing two LTO materials with same crystalline structure but different morphology that small particle size and large surface area has a beneficial effect on the battery performance. In addition, different behavior in terms of (de)lithiation voltages and lithium storage is observed in the LTO surface than in the bulk. Thus it is shown that the performance of LTO can be tailored by affecting the particle morphology. Moreover, the role of carbon additives in the LTO electrodes is studied. The effect of carbon additives on the performance of LTO electrodes is minimal when moderate conditions (low currents at room temperature) are used. However, in more demanding conditions (high currents and/or low temperatures) the beneficial effect of carbon additives is observed. The effect of carbon additives is more obvious with LTO with smaller particle size, and it is concluded that the effect of carbon additives depends both on the particle and electrode morphology. In the second part of the thesis, a water soluble acrylate binder Acryl S020 is studied for aqueous preparation of LTO and graphite negative electrodes. Commonly used PVDF (polyvinyledene fluoride) binder is costly and requires harmful NMP (N-methyl pyrrolidone) as a solvent and thus alternative methods are searched for. It is shown that similar capacities are achieved with LTO electrodes using an Acryl S020 binder manufactured with an aqueous process when compared to the LTO electrodes using a PVDF binder. Moreover, pilot scale slot die coating and gravure printing methods are tested in the electrode manufacturing and cycle lives of over 500 are obtained with both methods. Also water absorption/desorption of LTO is shown to be nearly reversible, and thus the aqueous process seems applicable for the preparation of LTO electrodes. Promising results are also obtained with the graphite electrodes using the Acryl S020 binder as better capacities at high C-rates and low temperature are achieved when compared to the graphite electrodes using a CMC (carboxymethyl cellulose) + SBR (styrenebutadiene rubber) binder combination.",

keywords = "lithium ion batteries, negative electrodes, electrode fabrication, litium-ioniakut, negatiivielektrodit, elektrodien valmistusmenetelm{\"a}t, lithium ion batteries, negative electrodes, electrode fabrication",

author = "Elina Pohjalainen",

year = "2016",

language = "English",

isbn = "978-952-60-6820-6",

series = "Aalto University publication series DOCTORAL DISSERTATIONS",

publisher = "Aalto University",

number = "97",

address = "Finland",

school = "Aalto University",

}

TY - BOOK

T1 - Negative Electrode Materials for Lithium Ion Batteries

AU - Pohjalainen, Elina

PY - 2016

Y1 - 2016

N2 - Lithium ion batteries have become the primary energy source for portable electronics, and their utilization in larger scale applications is increasing as well. Numerous electrode materials have been investigated for lithium ion batteries and several different materials are also found in commercial cells. The properties, cost and safety of the battery strongly depends on the selected electrode materials and cell design. The focus of this thesis is on negative electrode materials and electrode manufacturing methods that are environmentally friendly and safe for large scale and high power applications. First part of this thesis studies Li4Ti5O12 (LTO) as a negative electrode material. Especially the effect of the particle morphology on the electrochemical performance is evaluated in detail. It is shown by comparing two LTO materials with same crystalline structure but different morphology that small particle size and large surface area has a beneficial effect on the battery performance. In addition, different behavior in terms of (de)lithiation voltages and lithium storage is observed in the LTO surface than in the bulk. Thus it is shown that the performance of LTO can be tailored by affecting the particle morphology. Moreover, the role of carbon additives in the LTO electrodes is studied. The effect of carbon additives on the performance of LTO electrodes is minimal when moderate conditions (low currents at room temperature) are used. However, in more demanding conditions (high currents and/or low temperatures) the beneficial effect of carbon additives is observed. The effect of carbon additives is more obvious with LTO with smaller particle size, and it is concluded that the effect of carbon additives depends both on the particle and electrode morphology. In the second part of the thesis, a water soluble acrylate binder Acryl S020 is studied for aqueous preparation of LTO and graphite negative electrodes. Commonly used PVDF (polyvinyledene fluoride) binder is costly and requires harmful NMP (N-methyl pyrrolidone) as a solvent and thus alternative methods are searched for. It is shown that similar capacities are achieved with LTO electrodes using an Acryl S020 binder manufactured with an aqueous process when compared to the LTO electrodes using a PVDF binder. Moreover, pilot scale slot die coating and gravure printing methods are tested in the electrode manufacturing and cycle lives of over 500 are obtained with both methods. Also water absorption/desorption of LTO is shown to be nearly reversible, and thus the aqueous process seems applicable for the preparation of LTO electrodes. Promising results are also obtained with the graphite electrodes using the Acryl S020 binder as better capacities at high C-rates and low temperature are achieved when compared to the graphite electrodes using a CMC (carboxymethyl cellulose) + SBR (styrenebutadiene rubber) binder combination.

AB - Lithium ion batteries have become the primary energy source for portable electronics, and their utilization in larger scale applications is increasing as well. Numerous electrode materials have been investigated for lithium ion batteries and several different materials are also found in commercial cells. The properties, cost and safety of the battery strongly depends on the selected electrode materials and cell design. The focus of this thesis is on negative electrode materials and electrode manufacturing methods that are environmentally friendly and safe for large scale and high power applications. First part of this thesis studies Li4Ti5O12 (LTO) as a negative electrode material. Especially the effect of the particle morphology on the electrochemical performance is evaluated in detail. It is shown by comparing two LTO materials with same crystalline structure but different morphology that small particle size and large surface area has a beneficial effect on the battery performance. In addition, different behavior in terms of (de)lithiation voltages and lithium storage is observed in the LTO surface than in the bulk. Thus it is shown that the performance of LTO can be tailored by affecting the particle morphology. Moreover, the role of carbon additives in the LTO electrodes is studied. The effect of carbon additives on the performance of LTO electrodes is minimal when moderate conditions (low currents at room temperature) are used. However, in more demanding conditions (high currents and/or low temperatures) the beneficial effect of carbon additives is observed. The effect of carbon additives is more obvious with LTO with smaller particle size, and it is concluded that the effect of carbon additives depends both on the particle and electrode morphology. In the second part of the thesis, a water soluble acrylate binder Acryl S020 is studied for aqueous preparation of LTO and graphite negative electrodes. Commonly used PVDF (polyvinyledene fluoride) binder is costly and requires harmful NMP (N-methyl pyrrolidone) as a solvent and thus alternative methods are searched for. It is shown that similar capacities are achieved with LTO electrodes using an Acryl S020 binder manufactured with an aqueous process when compared to the LTO electrodes using a PVDF binder. Moreover, pilot scale slot die coating and gravure printing methods are tested in the electrode manufacturing and cycle lives of over 500 are obtained with both methods. Also water absorption/desorption of LTO is shown to be nearly reversible, and thus the aqueous process seems applicable for the preparation of LTO electrodes. Promising results are also obtained with the graphite electrodes using the Acryl S020 binder as better capacities at high C-rates and low temperature are achieved when compared to the graphite electrodes using a CMC (carboxymethyl cellulose) + SBR (styrenebutadiene rubber) binder combination.

KW - lithium ion batteries

KW - negative electrodes

KW - electrode fabrication

KW - litium-ioniakut

KW - negatiivielektrodit

KW - elektrodien valmistusmenetelmät

KW - lithium ion batteries

KW - negative electrodes

KW - electrode fabrication

M3 - Doctoral Thesis

SN - 978-952-60-6820-6

T3 - Aalto University publication series DOCTORAL DISSERTATIONS

PB - Aalto University

ER -

Negative Electrode Materials for Lithium Ion Batteries

Abstrakti

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