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.


Application of ab initio methods to secondary lithium batteries
Aydınol, Mehmet Kadri; Ceder, G. (1998-01-01)
Ab initio methods have started to be widely used in materials science for the prediction of properties of metals, alloys and compounds. These methods basically require only the atomic numbers of the constituent species. Such methods not only provide us with predictions of some of the properties of the material (even before synthesizing it) but also help us in understanding the phenomena that control those properties. The use of ab initio methods in the field of electrochemistry is, however, quite recent and...
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...
Bahtiyar, Doruk; Aydınol, Mehmet Kadri; Department of Metallurgical and Materials Engineering (2022-9)
For many years, materials in the form of metal sulfides, oxides, phosphates, and titanates have been developed as cathode and anode active materials to be used in energy storage devices. Borides and borates, recently, attracted the attention of researchers in this field. In this study, for the development of a new class of materials for energy storage applications, synthesis and characterization of metal (Fe, Mo, Mn, and V) borides and (Mn, and Y)borates were carried out. The obtained materials were tested ...
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...
Development of a paper-type tyrosinase biosensor for detection of phenolic compounds
Senyurt, Ozge; EYİDOĞAN, FÜSUN; Yilmaz, Remziye; Oz, M. Tufan; Ozalp, V. Cengiz; Arica, Yakup; Öktem, Hüseyin Avni (Wiley, 2015-01-01)
A low-cost, portable, and disposable paper-type tyrosinase biosensor was developed for determination of phenolic compounds, using a paper-strip absorption method. Tyrosinase and a chromophore (3-methyl-2-benzothiazolinone hydrazone) were immobilized on paper strips to manufacture the biosensor, which was tested on a nontoxic substrate (l-dopamine). The biosensor was responsive to phenolic compounds such as 4-chlorophenol, catechol, m-cresol, and p-cresol. The sensor showed stability for 70days. The develope...
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.