Atomic Layer Deposition of Titanium Dioxide on Activated Carbon for Negative electrode application in Supercapacitor
Awais, Muhammad Huzaifa (2025)
2025
Materiaalitekniikan DI-ohjelma - Master's Programme in Materials Engineering
Tekniikan ja luonnontieteiden tiedekunta - Faculty of Engineering and Natural Sciences
Hyväksymispäivämäärä
2025-12-23
Julkaisun pysyvä osoite on
https://urn.fi/URN:NBN:fi:tuni-2025121911994
https://urn.fi/URN:NBN:fi:tuni-2025121911994
Tiivistelmä
Supercapacitors have emerged as a critical energy storage technology due to their high-power density, rapid charge-discharge capabilities, and long cycle life. However, their energy density remains a limiting factor for widespread application. To address this, researchers have explored advanced electrode materials, particularly carbon-based structures such as graphene, carbon nanotubes, and activated carbon (AC). To enhance capacitance and stability, these carbon structures have been modified with metal oxides. Titanium dioxide (TiO₂) has gained attention due to its pseudocapacitive behavior and chemical stability. Atomic layer deposition (ALD) offers a precise and conformal method for depositing TiO₂ on porous carbon substrates, enabling controlled modification of electrochemical properties.
This thesis focuses on the synthesis of TiO₂-coated AC via ALD on industrially available YP-80F carbon (Kuraray) for application as a negative electrode in supercapacitors. The study aims to investigate the influence of ALD parameters (such as deposition temperature and number of cycles) on the electrochemical performance of TiO₂-coated AC electrodes. The resulting TiO₂-AC electrodes are then evaluated against unmodified YP-80F using cyclic voltammetry, galvanostatic charge-discharge, and capacitance retention tests. Subsequently, different material characterization techniques (FESEM, EDX, XRD, Raman spectroscopy, and ellipsometry) are employed to investigate the structure and morphology of the fabricated electrodes and ALD coating.
Based on the work conducted, the electrochemical improvement provided by ALD TiO₂ coating was minimal. In device configuration, the best-performing sample (140°C–40 Cycles) showed only a 4.5% increase in specific capacitance (27.9 F/g) compared to bare YP-80F (26.7 F/g), while three-electrode CV revealed an 18.3% improvement for the 100°C-10 Cycles sample (89.9 F/g versus 76.0 F/g for bare AC). Capacitance retention improved marginally from 95.7% for bare AC to 101.3% for 100°C-10 Cycles and 97.8% for 120°C-40 Cycles after 10,000 cycles. EDX weight percentage results showed a successful ALD operation, but without confirming coating conformality or morphology. Raman and XRD analyses indicated the deposited TiO₂ was amorphous. Thus, this work tentatively suggests that TiO₂ ALD provides only minimal performance enhancement. However, this cannot be considered an established conclusion due to insufficient sample replication, inconsistent electrochemical testing conditions, and limited advanced structural characterization.
This thesis focuses on the synthesis of TiO₂-coated AC via ALD on industrially available YP-80F carbon (Kuraray) for application as a negative electrode in supercapacitors. The study aims to investigate the influence of ALD parameters (such as deposition temperature and number of cycles) on the electrochemical performance of TiO₂-coated AC electrodes. The resulting TiO₂-AC electrodes are then evaluated against unmodified YP-80F using cyclic voltammetry, galvanostatic charge-discharge, and capacitance retention tests. Subsequently, different material characterization techniques (FESEM, EDX, XRD, Raman spectroscopy, and ellipsometry) are employed to investigate the structure and morphology of the fabricated electrodes and ALD coating.
Based on the work conducted, the electrochemical improvement provided by ALD TiO₂ coating was minimal. In device configuration, the best-performing sample (140°C–40 Cycles) showed only a 4.5% increase in specific capacitance (27.9 F/g) compared to bare YP-80F (26.7 F/g), while three-electrode CV revealed an 18.3% improvement for the 100°C-10 Cycles sample (89.9 F/g versus 76.0 F/g for bare AC). Capacitance retention improved marginally from 95.7% for bare AC to 101.3% for 100°C-10 Cycles and 97.8% for 120°C-40 Cycles after 10,000 cycles. EDX weight percentage results showed a successful ALD operation, but without confirming coating conformality or morphology. Raman and XRD analyses indicated the deposited TiO₂ was amorphous. Thus, this work tentatively suggests that TiO₂ ALD provides only minimal performance enhancement. However, this cannot be considered an established conclusion due to insufficient sample replication, inconsistent electrochemical testing conditions, and limited advanced structural characterization.