Synthesis and characterization of new micro-mesoporous carbide derived carbon materials for high energy and power density electrical double layer capacitors
Date
2015-07-09
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Abstract
Viimaste aastate geopoliitiliste kriiside taga on tihti võitlus piiratud energiaressursside üle. See on oluline, kuid kindlasti mitte ainus põhjus, miks on järjest rohkem hakatud rääkima energiajulgeolekust ning moodsate tehnoloogiate kasutuselevõtust selle saavutamiseks. Need moodsad tehnoloogiad põhinevad suuresti päikesest ja tuulest elektrienergia tootmisele, mida omakorda on vaja kombineerida erinevate energiasalvestusseadmetega. Paraku on vajalike energiamuundurite ning suure erimahtuvuse ja erivõimsusega energiasalvestite konstrueerimine ilma konkurentsivõimeliste ja efektiivsete superkondensaatoriteta äärmiselt keeruline. Kommertsiaalsed superkondensaatorid on viimasel aastakümnel teinud suure arenguhüppe ning nende kasutamine kasvab kiiresti. Siiski ei ole superkondensaatorite hinna ja kvaliteedi suhe piisavalt hea, et rakendada neid massiliselt elektrivõrkudes taastuvenergeetika efektiivsemaks muutmise nimel. Kuigi väga suure soovi korral saaks kogu maailm juba täna minna üle taastuvale ning mittereostavale energeetikale, oleks selle hind kõrge ning inimesed pole valmis seda investeeringut tegema.
Superkondensaatorite hinna ja kvaliteedi suhte parandamiseks on võimalik kas muuta tootmist odavamaks või oluliselt parandada seadmete elektrokeemilisi omadusi ning tõsta nende kvaliteeti. Üheks olulisimaks komponendiks superkondensaatoris on poorne kõrge eripinnaga elektrood, mille füüsikaline morfoloogia ja omadused määravad suuresti ka lõppprodukti karakteristikud nagu võimsus, mahtuvus ja eluiga. Selle tõttu on uute ning superkondensaatorites paremini käituvate elektroodimaterjalide väljatöötamine äärmiselt oluline. Tartu Ülikooli keemia instituudis on viimastel aastatel intensiivselt uuritud eriliste omadustega mikropoorse süsinikmaterjali sünteesi karbiididest ning selle kasutamist superkondensaatorite elektroodina. Me oleme võimelised üsna lihtsate meetoditega sünteesima väga unikaalsete füüsikaliste ja keemiliste omadustega süsinikmaterjale.
Käesoleva doktoritöö raames valmistati uudseid süsinikmaterjale erinevatest karbiididest kõrgtemperatuurse halogeenimise meetodil. Esialgu teostati materjalidele erinevad füüsikalised mõõtmised mille käigus saadi parem arusaam nende morfoloogiast, kristallilisusest ja keerukast poorsest struktuurist. Seejärel valmistati süsinikmaterjalidest superkondensaatori elektroodid ning teostati põhjalikud elektrokeemilised mõõtmised ja analüüs. Töö käigus saadud tulemuste põhjalikumal analüüsil leiti mitmeid selgepiirilisi korrelatsioone, kuidas materjalide erinevad füüsikalised karakteristikud mõjutavad superkondensaatori elektrokeemilisi omadusi. Selle tulemusel leiti, millised sünteesitud materjalid sobivad superkondensaatori elektroodideks paremini ning milliseid füüsikalisi parameetreid peaks eriti silmas pidama, kui otsida uusi hea hinna ja kvaliteedi suhtega materjale superkondensaatorite elektroodide valmistamiseks.
The geopolitical crises in recent years are often triggered by fights over limited energy resources. This is one of many reasons why it is becoming more and more important to invest in energy security and modern technologies. The latter are largely based on harvesting the energy of the sun and wind, which have to be backed up by various energy storage devices. The production of the necessary energy converter systems as well as high energy and power density storage systems is very difficult without competitive and efficient supercapacitors. In the last decade the commercial supercapacitors have made a great leap forward and their use is growing rapidly. However, their price-performance ratio is still not good enough to implement them on a large scale in electricity networks to make renewable energy more stable. If in great need, the world could meet its energy need from renewable resources even now. However, the price for this is still too high for the economically thinking mankind. To improve the price-performance ratio of supercapacitors there are two options: either lower the cost of production or significantly improve the electrochemical properties of supercapacitors. One of the key components in a supercapacitor is the porous electrode with a very high specific surface area. The morphology and physical characteristics of the electrode determine the supercapacitors electrochemical properties such as power density, capacity and lifetime. For these reasons, it is very important to develop new and better electrode materials for supercapacitors. In the Institute of Chemistry in University of Tartu a lot of work has been done in recent years to study unique carbon materials and their applicability to be used as supercapacitor electrodes. By fairly simple synthesis methods, we are capable of producing carbon materials with exceptional physical and electrochemical properties. In this work new carbon materials were produced from various carbides by means of high-temperature halogenation. Initially, these materials were physically characterized to better understand their morphology, crystallinity and complex porous structure. Thereafter the carbons were roll-pressed into supercapacitor electrodes and electrochemically analyzed. Clear correlations were established between the electrochemical and physical characteristics of the carbon materials synthesized. As a result, it was determined which materials were better suited for supercapacitor electrodes and which of the physical parameters should be especially kept in mind, when designing new materials for supercapacitors electrodes with a good price-performance ratio.
The geopolitical crises in recent years are often triggered by fights over limited energy resources. This is one of many reasons why it is becoming more and more important to invest in energy security and modern technologies. The latter are largely based on harvesting the energy of the sun and wind, which have to be backed up by various energy storage devices. The production of the necessary energy converter systems as well as high energy and power density storage systems is very difficult without competitive and efficient supercapacitors. In the last decade the commercial supercapacitors have made a great leap forward and their use is growing rapidly. However, their price-performance ratio is still not good enough to implement them on a large scale in electricity networks to make renewable energy more stable. If in great need, the world could meet its energy need from renewable resources even now. However, the price for this is still too high for the economically thinking mankind. To improve the price-performance ratio of supercapacitors there are two options: either lower the cost of production or significantly improve the electrochemical properties of supercapacitors. One of the key components in a supercapacitor is the porous electrode with a very high specific surface area. The morphology and physical characteristics of the electrode determine the supercapacitors electrochemical properties such as power density, capacity and lifetime. For these reasons, it is very important to develop new and better electrode materials for supercapacitors. In the Institute of Chemistry in University of Tartu a lot of work has been done in recent years to study unique carbon materials and their applicability to be used as supercapacitor electrodes. By fairly simple synthesis methods, we are capable of producing carbon materials with exceptional physical and electrochemical properties. In this work new carbon materials were produced from various carbides by means of high-temperature halogenation. Initially, these materials were physically characterized to better understand their morphology, crystallinity and complex porous structure. Thereafter the carbons were roll-pressed into supercapacitor electrodes and electrochemically analyzed. Clear correlations were established between the electrochemical and physical characteristics of the carbon materials synthesized. As a result, it was determined which materials were better suited for supercapacitor electrodes and which of the physical parameters should be especially kept in mind, when designing new materials for supercapacitors electrodes with a good price-performance ratio.
Description
Väitekirja elektrooniline versioon ei sisalda publikatsioone.
Keywords
süsinikelektroodid, carbon-electrodes