Department of Physics

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The Alkali (Li, Na) Based Solid State Ion Conductors Electrolytes for Solid State Batteries
(Library Information Services, COMSATS University Islamabad, Lahore Campus, 2022) ALEEMA MASOOD; CIIT/FA20-RPH-022/LHR; Dr. Rizwan Raza; LHR TP 7983
Initially, the energy storage devices based on liquid electrolytes are widely used to provide the continuous channel for energy transportation. Some drawbacks are (environmentally harmful and thermally unstable) that limits their commercial applications. While considering environmental aspects, the researchers move to find the environmental friendly, and thermally stable solid state electrolyte based energy storage devices. In this era, the solid state batteries become a center piece of research as the foremost candidate with great safety concern, high energy densities, cost effective and environmental friendly. In solid state batteries, the alkali based garnet type solid state electrolyte materials are thermally stable, eco-friendly, and have high energy density. In modern world, the consumption of lithium ion batteries surge day by day. There are limited raw resources for lithium, therefore researcher move to stir up to find alternative of lithium. Sodium can be considered as the best alternative of lithium. However, sodium is one of the most abundant element in the earth crust. In this research, alkali based garnet type solid state electrolyte as Li7La3Zr2O12 and Na2La3Zr2O12. The main objective of this work is to examine the ionic behavior, homogeneity, porosity, effect for the slid sate batteries. The x-rays diffraction is used to study the crystal structure of the material. The phase of the synthesized material is examined by high score expert. The prepared material is garnet type material with space group Fd-3m. The scanning electron microscopy is used to analyze the morphology of the synthesized electrolyte materials. The cyclic voltammetry and AC impedance spectroscopy are used to determine the charging and discharging rate, and ionic behavior of the materials. The ionic conductivity of both materials has comparable value for Li7La3Zr2O12 observed at room temperature 2.39×10 -6 Scm -1 . The optical band gap of both synthesized materials is analyzed by ultra violet visible spectroscopy. The Raman spectroscopy technique is used to determine the vibrational energy modes of both synthesized materials.
Electronic Structure and Energy Application of Layered Carbide Materials
(Library Information Services, COMSATS University Islamabad, Lahore Campus, 2022) Maria Sarfraz; CIIT/FA20-RPH-015/LHR; Dr. Rizwan Raza; LHR TP 7978
This project prepares the silicon carbide and MgZnO-based semiconductor materials for photocatalysis applications. An efficient photocatalytic material is required for proper working to enhance the efficiency of clean energy devices. The efficiency of photocatalysis water-splitting reaction has been limited. However, carbide and zinc oxide-based catalysts are developed to address such issues and discuss the reaction mechanism. Therefore, in this research work, SiC composite is made by hydrothermal method while MgZnO semiconductor materials are made by sol-gel method. To analyze the synthesized samples' structural properties, XRD has been carried out and find out SiC composite and MgZnO materials. RAMAN and UV spectroscopy is used to detect vibrational, rotational, and other states in a molecular system, and materials' optical properties have been studied, respectively. Further, electrochemical characterizations include EIS, Linear sweep voltammetry, and cyclic voltammetry. It has been observed that both materials are actively involved in electrochemical reactions. It can be concluded that the best performance among the two prepared samples is given by the model MgZnO. The reason is that MgZnO behaves like a promising photocatalyst compared to that SiC. Theoretical studies have been performed using Density Functional theory calculations to study the optical parameters, electronic structure, the density of states, and band gap
Synthesis of M1+xAlxTi2-x (PO4)3 (where M=Li or Na) Based Electrolyte Materials for Solid State Batteries and Study of their Electrochemical Properties
(Library Information Services, COMSATS University Islamabad, Lahore Campus, 2022) Zunaira Zulfiqar; CIIT/FA20-RPH-041/LHR; Dr. Rizwan Raza; LHR TP 7997
As "Necessity is the mother of invention", energy is stored from primary sources and released out, for consumption when there is a shortage of energy, to balance the life of human beings. In the modern world, sensational research has been done to design storage devices. While considering cost and environmental aspects, the researcher is impatient to find a friendlier environment and portable energy storage devices. The desire for environment-friendly and portable energy storage devices has steered the thorough investigation for all-solid-state rechargeable batteries. Solid state batteries have got attention because of more energy security and long life. Phosphate-based ceramic electrolytes are promising candidates for solid state electrolyte- based lithium and sodium-ion batteries. Sodium-ion batteries can potentially hold energy comparable to that of commercial lithium-ion batteries. Li resources are limited whereas sodium is one of the most abundant elements in the Earth’s crust. Rechargeable sodium cells are the ideal alternative to lithium-ion batteries based on material abundance and standard electrode potential. In this work, phosphate-based solid state electrolytes as M1+xAlxTi2-x (PO4)3 where M= Li, Na, and x = 0.5, are synthesized by solid state reaction and ball milling method. The main objective of this study is to examine the ionic behavior, homogeneity, porosity, crystal structure, and band-gap and also to determine the charging and discharging rate of the prepared material. The crystal structure of synthesized powder is examined by the x-rays diffraction technique. X pert high score software is used to determine the phase of the prepared material. Synthesized material has a single crystalline phase same as NASICON type material with space group R3̅c. Microstructure analysis is done by using scanning electron microscopy. The porosity of solid-state electrolytes is determined by the Archimedes method. The charging and discharging rate are examined by electrochemical techniques (AC-impendence-conductivity, cyclic voltammetry). The ionic conductivities of both have the same exponential value with 2.09×10-3 and 1.96×10-3 at 25°C, respectively. Ultraviolet spectroscopy is done to examine the band-gap. Tauc plot is used to determine band-gap for Li1.5Al0.5Ti1.5 (PO4)3 and the Na1.5Al0.5Ti1.5 (PO4)3. Raman spectroscopy is used to determine the vibrational energy modes of the prepared material

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