Grafen ve iletken polimerler (PEDOT:PSS, PANI) ile modifiye edilmiş karbon nanolif süperkapasitör elektrotların geliştirilmesi ve özelliklerinin incelenmesi
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Tarih
2020
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Yayıncı
Bursa Teknik Üniversitesi
Erişim Hakkı
info:eu-repo/semantics/closedAccess
Özet
Yenilenebilir enerjinin etkili kullanılabilmesi için enerji depolama teknolojileri ile birlikte kullanımı önem arz etmektedir. Süperkapasitörler, güç ve enerji yoğunluğu açısından Li-iyon pil teknolojisi ve konvansiyonel kapasitörler arasındaki boşluğu dolduran enerji depolama teknolojileridir. Bu tez kapsamında, karbon nanolif elektrot malzemesi, çeşitli malzemeler (grafen, PEDOT:PSS ve PANI) ve yöntemler (elektroüretim, elektrosprey, daldırarak kaplama ve nanolif iplik üretimi) ile modifiye edilerek elektrokimyasal performansın arttırılması amaçlanmıştır. Bu amaçla öncellikle, PAN nanolif üretim prosesi optimize edilerek düzgün, homojen, sürekli, hızlı ve ince nanolif üretim için parametreler tespit edilmiş ve bu şartlar altında, ortalama 233±32 nm çapta nanolifler üretilmiştir. Stabilizasyon ve karbonizasyon işleminden sonra nanolif çapları sırasıyla 209±16 nm ve 140±17 nm olarak ölçülmüştür. Sonraki çalışmada, farklı oranlarda PAN/PVA hibrit nanolif yapıları üretilmiş ve üretim sırasında yapıdan PVA uzaklaştırılarak gözenekli karbon nanolif elektrotlar elde edilmiştir. Yüzey alanı arttırılan gözenekli karbon nanolif elektrotların kimyasal, morfolojik ve elektrokimyasal performansı incelenmiştir. %33 PVA içeren hibrit nanoliften üretilen EK5 elektrodunun 5 mV/s tarama hızındaki spesifik kapasitans değerinin ham karbon nanolife kıyasla %64 geliştirildiği tespit edilmiş ve spesifik kapasitans değeri 268 F/g olarak ölçülmüştür. Ayrıca gözenekli karbon nanolif elektrotlar, 2500 test döngüsü boyunca spesifik kapasitansın yaklaşık %100'ü korunmuş ve üstün döngüsel stabilite sergilemiştir. Bir sonraki çalışmada, suda çözünebilen bir iletken polimer olan PEDOT:PSS polimeri kolay, hızlı ve ölçeklendirilebilir bir yöntem olan daldırarak kaplama yöntemi kullanılarak farklı kalınlıklarda karbon nanolif yüzeyine kaplanmış ve PEDOT:PSS kaplama işleminin karbon nanolifin elektrokimyasal performansına etkisi incelenmiştir. 155,44 nm olan ham karbon nanolif çapı, 9 kat PEDOT:PSS kaplanması sonrasında, 194,45 nm olarak ölçülmüştür. 9 kat PEDOT:PSS kaplama sonrasında (9P-KNF) ile 10 mV/s tarama hızında, en yüksek spesifik kapasitans 175 F/g olarak elde edilmiştir. Bu değer ham karbon nanolifin spesifik kapasitans değerinden yaklaşık %75,9 fazla olmuştur. 2500 döngü sonrasında ise %80'lik bir kapasitans korunumu göstermiştir. Diğer çalışmada, elektroüretim öncesinde PAN çözeltisi içerisine %1, 2, 5, 10 ve 20 gibi farklı oranlarda grafen oksit ilave edilerek, grafen oksit katkılı PAN nanolifler üretilmiş ve elde edilen yapılar stabilize ve karbonize edilmiştir, böylece farklı xx oranlarda grafen katkılı karbon nanolif yapılar elde edilmiştir. Sonrasında en iyi elektrokimyasal performans gösteren %10 GO katkılı karbon nanolif (KPGO10 elektrodunun spesifik kapasitans değeri 5 mV/s tarama hızında 164 F/g olarak hesaplanmıştır) yüzeyine hiyerarşik yapıda sentezlenen polianilin (PANI) iletken polimeri vakum destekli süzme yöntemi ile yapıya entegre edilmiş ve PANI ile modifiye edilmiş grafen katkılı karbon nanolif elektrot performansı incelenmiş ve spesifik kapasitans değerinin yaklaşık %20 geliştirildiği görülmüştür. Sonraki çalışmada, grafen oksit dispersiyonu %4, 8, 20 gibi farklı oranlarda PAN nanolif yüzeyine elektrosprey yöntemi ile kaplanmıştır. GO kaplı PAN nanolif yüzey, stabilize ve karbonize edilerek grafen kaplı karbon nanolif yüzeyler elde edilmiştir. Elde edilen süperkapasitör elektrotların elektrokimyasal performansları incelenmiş ve en iyi sonuçların %8 GO elektrosprey edilmiş karbon nanolif elektrotlar ile elde edildiği görülmüştür. Son çalışmada ise, elektroüretim ile elde edilmiş PAN nanolif yapısından, şeritler ve sonrasında büküm işlemi uygulanarak PAN nanolif iplikler elde edilmiştir. Elde edilen PAN nanolif iplikler, stabilize ve karbonize edilerek karbon nanolif iplikler elde edilmiş sonrasında morfolojik ve elektrokimyasal performansları incelenmiştir. KNF iplik elektrodun spesifik kapasitans değeri 0,2 A/g akım yoğunluğunda 145 F/g olarak ölçülmüştür ve spesifik kapasitans değerinin 500 döngüye kadar yaklaşık %20 arttığı, sonrasında 1000 döngüye kadar yaklaşık sabit kaldığı tespit edilmiştir.
In order to use renewable energy effectively, it is important to use it together with energy storage technologies. Supercapacitors are energy storage technologies that fill the gap between Li-ion battery technology and conventional capacitors in terms of power and energy density. Within the scope of this thesis, it is aimed to increase the electrochemical performance by modifying the carbon nanofiber electrode material with various materials (graphene, PEDOT: PSS, and PANI) and methods (electrospinning, electrospray, dip coating, and nanofiber yarn production). For this purpose, PAN nanofiber production parameters were optimized to produce smooth, homogeneous, continuous, fast and fine nanofiber, and then nanofibers with an average diameter of 233±32 nm were produced under optimized conditions. After stabilization and carbonization process, nanofiber diameters were measured as 209±16 nm and 140±17 nm, respectively. In the next study, PAN/PVA hybrid nanofiber structures were produced in different mixing ratios and porous carbon nanofiber electrodes were obtained by removing PVA from the nanofiber structure during production. The chemical, morphological, and electrochemical performance of porous carbon nanofiber electrodes with the increased surface area were investigated. It was determined that the specific capacitance value of the EK5 electrode produced from hybrid nanofiber containing 33% PVA at 5 mV/s scan rate was improved by 64% compared to the neat carbon nanofiber and the specific capacitance value was measured as 268 F/g. In addition, porous carbon nanofiber electrodes retained approximately 100% of the specific capacitance during 2500 test cycles and exhibited superior cyclic stability. In the next study, PEDOT:PSS, a water-soluble conductive polymer, was coated on the carbon nanofiber surface in different thicknesses using the dip-coating method, which is an easy, fast and scalable method, and the effect of the PEDOT:PSS coating process on the electrochemical performance of the carbon nanofiber was investigated. The neat carbon nanofiber diameter of 155.44 nm was measured as 194.45 nm after 9 layers of PEDOT: PSS coating. After 9 layers of PEDOT: PSS coating (9P-KNF), the highest specific capacitance was obtained as 175 F/g at 10 mV/s scan rate, this value was approximately 75.9% higher than the specific capacitance value of the neat carbon nanofiber. After 2500 cycles, it showed an 80% capacitance retention. In another study, by adding graphene oxide (GO) in different mixing ratios such as 1, 2, 5, 10, and 20% into the PAN solution before electrospinning, graphene oxide-reinforced PAN nanofibers were produced. The produced nanofiber mats were stabilized and carbonized so that different proportions of graphene-reinforced carbon nanofiber structures were obtained. Afterward, hierarchical synthesized the conductive polymer of polyaniline (PANI) was integrated into the 10% GO-reinforced carbon nanofiber electrode, which showed the best electrochemical performance (the specific capacitance value of the KPGO10 electrode was calculated as 164 F/g at a scan rate of 5 mV/s), by the vacuum-assisted filtration method. The performance of the graphene-reinforced carbon nanofiber electrode modified with PANI was examined and it was seen that the specific capacitance value was improved by about 20%. In the next study, the graphene oxide dispersion was electrospray coated on the PAN nanofiber surface in different proportions such as 4, 8, 20%. GO-coated PAN nanofiber surfaces have been stabilized and carbonized to obtain graphene-coated carbon nanofiber surfaces. The electrochemical performances of the obtained supercapacitor electrodes were examined and it was seen that the best results were obtained with 8% GO-electrosprayed carbon nanofiber electrodes. In the last study, PAN nanofiber yarns were obtained from the PAN nanofiber yarn structure obtained by electrospinning and then the twisting process. The obtained PAN nanofiber yarns were stabilized and carbonized and carbon nanofiber yarns were obtained. Then morphological and electrochemical performances of carbon nanofiber yarns were examined. The specific capacitance value of the CNF yarn electrode was measured as 145 F/g at a current density of 0.2 A/g, and it was found that the specific capacitance value increased by approximately 20% up to 500 cycles, then remained approximately constant until 1000 cycles.
In order to use renewable energy effectively, it is important to use it together with energy storage technologies. Supercapacitors are energy storage technologies that fill the gap between Li-ion battery technology and conventional capacitors in terms of power and energy density. Within the scope of this thesis, it is aimed to increase the electrochemical performance by modifying the carbon nanofiber electrode material with various materials (graphene, PEDOT: PSS, and PANI) and methods (electrospinning, electrospray, dip coating, and nanofiber yarn production). For this purpose, PAN nanofiber production parameters were optimized to produce smooth, homogeneous, continuous, fast and fine nanofiber, and then nanofibers with an average diameter of 233±32 nm were produced under optimized conditions. After stabilization and carbonization process, nanofiber diameters were measured as 209±16 nm and 140±17 nm, respectively. In the next study, PAN/PVA hybrid nanofiber structures were produced in different mixing ratios and porous carbon nanofiber electrodes were obtained by removing PVA from the nanofiber structure during production. The chemical, morphological, and electrochemical performance of porous carbon nanofiber electrodes with the increased surface area were investigated. It was determined that the specific capacitance value of the EK5 electrode produced from hybrid nanofiber containing 33% PVA at 5 mV/s scan rate was improved by 64% compared to the neat carbon nanofiber and the specific capacitance value was measured as 268 F/g. In addition, porous carbon nanofiber electrodes retained approximately 100% of the specific capacitance during 2500 test cycles and exhibited superior cyclic stability. In the next study, PEDOT:PSS, a water-soluble conductive polymer, was coated on the carbon nanofiber surface in different thicknesses using the dip-coating method, which is an easy, fast and scalable method, and the effect of the PEDOT:PSS coating process on the electrochemical performance of the carbon nanofiber was investigated. The neat carbon nanofiber diameter of 155.44 nm was measured as 194.45 nm after 9 layers of PEDOT: PSS coating. After 9 layers of PEDOT: PSS coating (9P-KNF), the highest specific capacitance was obtained as 175 F/g at 10 mV/s scan rate, this value was approximately 75.9% higher than the specific capacitance value of the neat carbon nanofiber. After 2500 cycles, it showed an 80% capacitance retention. In another study, by adding graphene oxide (GO) in different mixing ratios such as 1, 2, 5, 10, and 20% into the PAN solution before electrospinning, graphene oxide-reinforced PAN nanofibers were produced. The produced nanofiber mats were stabilized and carbonized so that different proportions of graphene-reinforced carbon nanofiber structures were obtained. Afterward, hierarchical synthesized the conductive polymer of polyaniline (PANI) was integrated into the 10% GO-reinforced carbon nanofiber electrode, which showed the best electrochemical performance (the specific capacitance value of the KPGO10 electrode was calculated as 164 F/g at a scan rate of 5 mV/s), by the vacuum-assisted filtration method. The performance of the graphene-reinforced carbon nanofiber electrode modified with PANI was examined and it was seen that the specific capacitance value was improved by about 20%. In the next study, the graphene oxide dispersion was electrospray coated on the PAN nanofiber surface in different proportions such as 4, 8, 20%. GO-coated PAN nanofiber surfaces have been stabilized and carbonized to obtain graphene-coated carbon nanofiber surfaces. The electrochemical performances of the obtained supercapacitor electrodes were examined and it was seen that the best results were obtained with 8% GO-electrosprayed carbon nanofiber electrodes. In the last study, PAN nanofiber yarns were obtained from the PAN nanofiber yarn structure obtained by electrospinning and then the twisting process. The obtained PAN nanofiber yarns were stabilized and carbonized and carbon nanofiber yarns were obtained. Then morphological and electrochemical performances of carbon nanofiber yarns were examined. The specific capacitance value of the CNF yarn electrode was measured as 145 F/g at a current density of 0.2 A/g, and it was found that the specific capacitance value increased by approximately 20% up to 500 cycles, then remained approximately constant until 1000 cycles.
Açıklama
Anahtar Kelimeler
Enerji, Energy, Kimya Mühendisliği, Chemical Engineering, Polimer Bilim ve Teknolojisi, Polymer Science and Technology
