Development and characterization of high power density cathode materials for lithium-ion batteries

Doğu, Şafak
In this thesis, facile and cost efficient aqua based synthesis method is developed to synthesize power dense and fast rechargeable LiFePO4 cathode materials. In order to obtain nano sized crystal morphology, nucleation controlled techniques were studied on precursor synthesis. These techniques are freeze (cryogenic) drying with co-precipitation and ultrasound assisted sub-sequential precipitation with vacuum drying at low temperatures (<350 K). In co-precipitation with freeze drying synthesis, star-like platelet LiFePO4 was synthesized while ultrasound assisted sub-sequential precipitation synthesis yielded 2D polycrystalline nano-plate structures around 100 nm thickness which has high tap density. The morphology of particles was diverted by manipulation of nucleation and crystallization processes and then preserved with carbon encapsulation strategy before LiFePO4 formation through calcination. The highest discharge capacity is found as 140.3 mAhg–1 at 0.1C cycling rate for LiFePO4/C synthesized by ultrasound assisted sub-sequential precipitation and carbonized via CVD. The highest and endurable electrochemical performance was achieved with sucrose encapsulated LiFePO4/C where the thinnest plate-like LiFePO4 (40 – 100 nm) was synthesized via ultrasonicated formation of vivianite precursors. The rechargeable capacities are found as 125.1 and 89.2 mAhg–1 at slow (0.1C) and fast (1C) discharge rates, respectively. Regarding to these slow and fast rated discharge capacities, higher capacity retentions (82 – 90%) were observed as 103.8 and 81 mAhg–1 coulombic capacities even after less than 1 hour fast charging. Through this synthesis technique, especially in fast charging, it is able to achieve more discharge capacity than other high temperature hydro/solvothermal synthesis.


Development and characterization of high energy cathode materials for lithium-ion batteries
Büyükburç, Atıl; Aydınol, Mehmet Kadri; Department of Metallurgical and Materials Engineering (2013)
The aim of this thesis is to produce high energy cathode materials based on LiCoO2 materials with the general formula LiCo1-xMxO2 and LiCo1-y-xMxNyO2. In order to achieve this formula, less exploited doping elements such as Mo, Cr and W will be used as well as Mn. During the study, the parameters of the processes which are solution preparation, freeze drying and calcination are optimized. According to the results, 24 hours of freeze drying is enough for drying the samples. Calcination at lower (< 700°C) tem...
Development and characterization of tungstates and molybdates for li-ion batteries
Kaygusuz, Burçin; Aydınol, Mehmet Kadri; Department of Metallurgical and Materials Engineering (2016)
In recent years, the need for portable power, lithium ion batteries dominate the markets because of their advantages. Metal tungstates and molybdates (Metals: Fe, Ni, Co, Mn, Zn, Mg) are two important families of inorganic materials and have found many applications in various fields, such as catalysis, magnetic applications, humidity sensors, and photoluminescence. However, their use in energy storage applications is almost none. The tungstates and molybdates adapt monoclinic crystal structure and crystalli...
Production of inorganic charge selective layers for mesoscopic perovskite solar cells
İçli, Kerem Çağatay; Özenbaş, Ahmet Macit; Akata Kurç, Burcu; Department of Micro and Nanotechnology (2017)
In this work, nanoparticles of lithium doped nickel oxide (NiO) were synthesized by common wet chemistry methods like precipitation, ultrasonic spray pyrolysis and flame spray pyrolysis methods. Synthesized nanoparticles were employed in fully metal oxide mesoscopic perovskite based solar cells. Lithium doping of NiO was achieved by ultrasonic spray pyrolysis method and flame spray pyrolysis methods. Flame spray pyrolysis method was used to synthesize yttrium doped titanium dioxide (TiO2) and magnesium oxid...
Development and characterization of tin based anode materials for Li-Ion batteries
Yılmaz, Emre; Aydınol, Mehmet Kadri; Department of Metallurgical and Materials Engineering (2018)
Li-ion batteries are the most popular type of portable secondary batteries. They generate electrons at anode electrode during discharging process by releasing $Li^+$ ions from anode, in which graphite is used as Li reservoir. Recently, $SiO_2$ and Tin (IV) Oxide materials are investigated as anode materials by researchers, due to their very high theoretical capacity. There are two problems, however, limiting their use which are pulverization and irreversible reaction problems. These problems are, also, the ...
Applications of ions produced by low intensity repetitive laser pulses for implantation into semiconductor materials
Wolowski, J.; Badziak, J.; Czarnecka, A.; Parys, P.; Pisarek, M.; Rosinski, M.; Turan, Raşit; Yerci, Selçuk (2008-01-01)
This work reports experiment concerning specific applications of implantation of laser-produced ions for production of semiconductor nanocrystals. The investigation was carried out in the IPPLM within the EC STREP 'SEMINANO' project. A repetitive pulse laser system of parameters: energy up to 0.8 J in a 3.5 ns-pulse, wavelength of 1.06 mu m, repetition rate of up to 10 Hz, has been employed in these investigations. The characterisation of laser-produced ions was performed with the use of 'time-of-flight' io...
Citation Formats
Ş. Doğu, “Development and characterization of high power density cathode materials for lithium-ion batteries,” Ph.D. - Doctoral Program, Middle East Technical University, 2015.