Hydrothermal synthesis and characterization of LiMnPO4 for secondary lithium batteries /

Camcı, Esin
The mechanism in Li-ion batteries is based on the motion of Li+ ion between positive and negative electrodes. As Li-ion batteries have attracted much attention, the demand for high capacity and low cost electrode materials has increased. Lithium manganese phosphate (LMnP) is one of the most promising cathode materials. It highly satisfies the lithiation and de-lithiation process of Li-ion technology due to its olivine structure. Moreover, it has high theoretical capacity, it is safety and low cost. The drawback of LMnP is its poor ionic and electronic conductivity. The aim of this thesis is to optimize the hydrothermal process parameters for the synthesis of pure and well-crystalline LMnP, dope the Mn-site in the olivine structure with cobalt, chromium, molybdenum, vanadium and tungsten and eventually electrochemically characterize the samples to analyze the effect of doping. The structure and topography of the obtained powders were investigated with X-Ray Diffraction and Scanning Electron Microscopy. Also, the electrochemical characteristics were determined by different techniques; cycle tests, charge-discharge, Cyclic Voltammetry and Electrochemical Impedance Spectroscopy. According to the results, doping process was successful to show better performance than pristine LMnP. After pure LMnP and its doped versions were analyzed, it is understood that cobalt and vanadium enhances the electrical and ionic conductivity of LMnP; whereas, chromium has an influence on the rate capability of LMnP


Residual stress and Young's modulus measurement of capacitive micromachined ultrasonic transducer membranes
Yaralioglu, GG; Ergun, AS; Bayram, Barış; Marentis, T; Khuri-Yakub, BT (2001-01-01)
Membranes supported by posts are used as vibrating elements of capacitive micromachined ultrasonic transducers (CMUTs). The residual stress built up during the fabrication process determines the transducer properties such as resonance frequency, collapse voltage, and gap distance. Hence, it is important to evaluate and control the stress in thin film CMUT membranes. The residual stress in the membrane causes significant vertical displacements at the center of the membrane. The stress bends the membrane post...
Gholami, Mehrdad; Farjoud, Mohammad Javad; Sepehri, Masoud; Nazari, Ammar; Gholami, Majid; Behkami, Shima; Ataman, Osman Yavuz (2011-01-01)
Slotted Quartz Tube (SQT) is a simple device that provides a sensitivity enhancement of 2-5 times in Flame Atomic Absorption Spectrometry (FAAS) depending on the element. A Gas Screen-Slotted Quartz Tube (GS-SQT) was designed to further increase sensitivity. For this purpose, two slotted gas chambers were fixed on the left and right sides of a burner head and Ar gas was supplied into these chambers perpendicular to the light path to produce two thin layers of gas screen. It was observed that these Ar screen...
Extraction Using Moderate Electric Fields
Şensoy, İlkay (2004-01-01)
During moderate electric field (MEF) processing, a voltage applied across a food material may affect the permeability of cell membranes. It is known that high electric fields can cause either reversible or irreversible rupture of cell membranes. In this research, the effect of MEF processing on permeability was studied. Effects of frequency and electric field strength were investigated. Cellular structure was investigated by transmission electron microscopy (TEM). Fermented black tea leaves and fresh or dry...
Active vibration suppression of a smart beam via self sensing piezoelectric actuator
Uğur, Arıdoğan; Şahin, Melin; Yaman, Yavuz; Volkan, Nalbantoğlu (null; 2009-08-17)
In this paper, an active vibration suppression of a smart beam using self-sensing piezoelectric actuator is presented. The smart beam is composed of a cantilever aluminium beam with four surface-bonded piezoelectric patches symmetrically located both side of the beam. Piezoelectric materials can transform mechanical deformation to electric signal and vice versa. This property of piezoelectric materials enables them to be used as an actuator and a sensor. In self-sensing actuator configuration, the piezoelec...
Differential charging in SiO2/Si system as determined by XPS
Karadas, F; Ertaş, Gülay; Suzer, S (American Chemical Society (ACS), 2004-01-29)
The Si2p binding and the Si-KLL kinetic energy difference between the SiO2 layer and Si substrate is shown to be influenced by application of external voltage bias to the sample holder due to the differential charging as was already reported earlier (Ulgut, B.; Suzer, S. J. Phys. Chem. B 2003, 107, 2939). The cause of this bias induced (physical)-shift is now proven to be mostly due to partial neutralization by the stray electrons within the vacuum system by (i) introducing additional stray electrons via a ...
Citation Formats
E. Camcı, “Hydrothermal synthesis and characterization of LiMnPO4 for secondary lithium batteries /,” M.S. - Master of Science, Middle East Technical University, 2014.