Hasanul Karim

Investigation of modified graphene for energy storage applications.

Lithium-ion batteries (LIB) have been receiving extensive attention because of the high specific energy density for wide applications such as electronic vehicles, commercial mobile electronics, and military applications. In LIB, graphite is the most commonly used anode material; however, lithium-ion intercalation in graphite is limited, hindering the battery charge rate and capacity. To overcome this obstacle, nanostructured anode assembly has been extensively studied to increase the lithium-ion diffusion rate. Among these approaches, high specific surface area metal oxide nanowires connecting nanostructured carbon materials accumulation have shown propitious results for enhanced lithium intercalation. Recently, nanowire/graphene hybrids were developed for the enhancement of LIB performance; however, almost all previous efforts employed nanowires on graphene in a random fashion, which limited lithium-ion diffusion rate. Therefore, we demonstrate a new approach by hydrothermally growing uniform nanowires on graphene aerogel to further improve the performance. This nanowire/graphene aerogel hybrid not only uses the high surface area of the graphene aerogel but also increases the specific surface area for electrode-electrolyte interaction. Therefore, this new nanowire/graphene aerogel hybrid anode material could enhance the specific capacity and charge-discharge rate. Scanning electron microscopy (SEM) and X-ray diffraction (XRD) are used for materials characterization. Battery analyzer and potentio-galvanostat are used for measuring the electrical performance of the battery. The testing results show that nanowire graphene hybrid anode gives significantly improved performance compared to graphene anode.

Nanowire modified carbon fibers for enhanced electrical energy storage

The study of electrochemical super-capacitors has become one of the most attractive topics in both academia and industry as energy storage devices because of their high power density, long life cycles, and high charge/discharge efficiency. Recently, there has been increasing interest in the development of multifunctional structural energy storage devices such as structural super-capacitors for applications in aerospace, automobiles, and portable electronics. These multifunctional structural super-capacitors provide structures combining energy storage and load bearing functionalities, leading to material systems with reduced volume and/or weight. Due to their superior materials properties, carbon fiber composites have been widely used in structural applications for aerospace and automotive industries. Besides, carbon fiber has good electrical conductivity which will provide lower equivalent series resistance; therefore, it can be an excellent candidate for structural energy storage applications. Hence, this paper is focused on performing a pilot study for using nanowire/carbon fiber hybrids as building materials for structural energy storage materials; aiming at enhancing the charge/discharge rate and energy density. This hybrid material combines the high specific surface area of carbon fiber and pseudo-capacitive effect of metal oxide nanowires, which were grown hydrothermally in an aligned fashion on carbon fibers. The aligned nanowire array could provide a higher specific surface area that leads to high electrode-electrolyte contact area thus fast ion diffusion rates. Scanning Electron Microscopy and X-Ray Diffraction measurements are used for the initial characterization of this nanowire/carbon fiber hybrid material system. Electrochemical testing is performed using a potentio-galvanostat. The results show that gold sputtered nanowire carbon fiber hybrid provides 65.9% higher energy density than bare carbon fiber cloth as super-capacitor.

Microwave exfoliated graphene oxide/TiO2 nanowire hybrid for high performance lithium ion battery

Lithium ion battery (LIB) is a key solution to the demand of ever-improving, high energy density, clean-alternative energy systems. In LIB, graphite is the most commonly used anode material; however, lithium-ion intercalation in graphite is limited, hindering the battery charge rate and capacity. To date, one of the approaches in LIB performance improvement is by using porous carbon (PC) to replace graphite as anode material. PCs pore structure facilitates ion transport and has been proven to be an excellent anode material candidate in high power density LIBs. In addition, to overcome the limited lithium-ion intercalation obstacle, nanostructured anode assembly has been extensively studied to increase the lithium-ion diffusion rate. Among these approaches, high specific surface area metal oxide nanowires connecting nanostructured carbon materials accumulation have shown promising results for enhanced lithium-ion intercalation. Herein, we demonstrate a hydrothermal approach of growing TiO2 nanowires (TON) on microwave exfoliated graphene oxide (MEGO) to further improve LIB performance over PC. This MEGO-TON hybrid not only uses the high surface area of MEGO but also increases the specific surface area for electrode–electrolyte interaction. Therefore, this new nanowire/MEGO hybrid anode material enhances both the specific capacity and charge–discharge rate. Scanning electron microscopy and X-ray diffraction were used for materials characterization. Battery analyzer was used for measuring the electrical performance of the battery. The testing results have shown that MEGO-TON hybrid provides up to 80% increment of specific capacity compared to PC anode.

Feasibility study of thermal energy harvesting using lead free pyroelectrics

Energy harvesting has significant potential for applications in energizing wireless sensors and charging energy storage devices. To date, one of the most widely investigated materials for mechanical and thermal energy harvesting is lead zirconate titanate (PZT). However, lead has detrimental effects on the environment and on health. Hence, alternative materials are required for this purpose. In this paper, a lead free material, lithium niobate (LNB) is investigated as a potential material for pyroelectric energy harvesting. Although its theoretical pyroelectric properties are lower compared to PZT, it has better properties than other lead free alternatives such as ZnO. In addition, LNB has a high Curie temperature of about 1142 °C, which makes it applicable for high temperature energy harvesting, where other pyroelectric ceramics are not suitable. Herein, an energy harvesting and storage system composed of a single crystal LNB and a porous carbon-based super-capacitor was investigated. It is found that with controlled heating and cooling, a single wafer of LNB (75 mm diameter and 0.5 mm thickness) could generate 437.72 nW cm–3 of power and it could be used to charge a super-capacitor with a charging rate of 2.63 mV (h cm3)–1.

A Lithium Niobate High-Temperature Sensor for Energy System Applications

Temperature monitoring for energy generation systems plays an important role for the control of overall safety and efficiency. To run the energy system at optimum operating conditions, it is important to measure the real-time temperature. Furthermore, harsh environment temperature sensing is desired, since most sensors in energy systems are exposed to high temperature, high pressure, and corrosive environments. Lithium niobate (LiNbO3) has high Curie temperature (1210 °C), thus making it promising to be used as a sensor material for high-temperature applications. In this paper, a study has been conducted to actively measure the temperature up to 450 °C using a pyroelectric ceramic LiNbO3 as a sensor material. A 1 cm × 1 cm sample of LiNbO3 ceramic with 0.2 cm thickness was prepared as a sensor. The LiNbO3 sensor and a K-type thermocouple were placed inside a tube furnace to sense the temperature. Different temperature setting conditions were applied to the sensor, including slow heating rate, high heating rate, and steady-state conditions for prolonged time period to validate readability and repeatability of the sensor. Temperatures were calculated using current generated from the sensor upon heating or cooling. The calculated temperature from the sensor was compared with the temperature measured by the K-type thermocouple. A range of deviation from 2% to 11% was found between the temperature measured by LiNbO3 and thermocouple.

High-performance porous carbon/CeO2 nanoparticles hybrid super-capacitors for energy storage

Increasing demand for energy storage devices has propelled researchers for developing efficient super-capacitors (SC) with long cycle life and ultrahigh energy density. Carbon-based materials are commonly used as electrode materials for SC. Herein we report a new approach to improve the SC performance utilizing porous carbon /Cerium oxide nanoparticle (PC-CON) hybrid as electrode material synthesized via low temperature hydrothermal method and tetraethyl ammonium tetrafluroborate in acetonitrile as organic electrolyte. Through this approach, charges can be stored not only via electrochemical double layer capacitance (EDLC) from PC but also through pseudo-capacitive effect from CeO2 NPs. The excellent electrode-electrolyte interaction due to the electrochemical properties of the ionic electrolyte provides a better voltage window for the SC. Scanning Electron Microscopy (SEM), Transmission Electron Microscopy (TEM) and X-Ray Diffraction (XRD) measurements were used for the initial characterization of this PC/CeO2 NPs hybrid material system. Electrochemical measurements of SCs was performed using a potentio-galvanostat. It is found that the specific capacitance was improved by 30% using PC-CON system compared with pristine PC system.

Modeling, fabrication, and testing of metamaterial based wireless temperature sensor (Conference Presentation)

This paper presents the fabrication, modeling and testing of a metamaterial based passive wireless temperature sensor consisting of an array of closed ring resonators (CRRs) embedded in a dielectric material matrix. A mixture of 70 vol% Boron Nitride (BN) and 30 vol% Barium Titanate (BTO) is used as the dielectric matrix and copper washers are used as CRRs. Conventional powder compression is used for the sensor fabrication. The feasibility of wireless temperature sensing is demonstrated up to 200 C. The resonance frequency of the sensor decreases from 11.93 GHz at room temperature to 11.85 GHz at 200 C, providing a sensitivity of 0.462 MHz/C. The repeatability of temperature sensing tests was carried out to quantify the repeatability. The highest standard deviation observed was 0.012 GHz at 200 C.

Pyroelectric energy harvesting with a high Curie temperature material LiNbO3

Energy harvesting has been gaining significant interest as a potential solution for energizing next generation sensor and energy storage devices. The most widely investigated material for piezoelectric and pyro-electric energy harvesting to date is PZT (Lead Zirconate Titanate), owing to its good piezoelectric and pyro-electric properties. However, Lead is detrimental to human health and to the environment. Hence, alternative materials are required to be investigated for this purpose. In this paper, a lead free material Lithium Niobate (LNB) is reported as a potential material for pyro-electric energy harvesting. Although, it has lower pyro-electric properties than PZT, it has better properties than other lead free alternatives of PZT such as ZnO. In addition, LNB has a high curie point of 1142 °C, which makes it suitable for high temperature environment where other pyro-electric materials are not suitable. Therefore, a single crystal LNB has been investigated as a source of energy harvesting under alternative heating and cooling environment. A commercial 0.2 F super-capacitor was used as the energy storage device.

Porous carbon/CeO2 composites for Li-ion battery application

Development of new materials hold the key to the fundamental progress in energy storage systems such as Li-ion battery, which is widely used in modern technologies because of their high energy density and extended cycle life. Among these materials, porous carbon is of particular interest because it provides high lithiation and excellent cycling capability by shortening the transport length for Li+ ions with large electrode/electrolyte interface. It has also been demonstrated that transition metal oxide nanoparticle can enhance surface electrochemical reactivity and increase the capacity retention capability for higher number of cycles. Here we investigate porous carbon/ceria (CeO2) nanoparticles composites as an anode material. The high redox potential of ceria is expected to provide a higher potential window as well as increase the specific capacity and energy density of the system. Scanning Electron Microscopy (SEM), X-Ray Diffraction (XRD), Transmission Electron Microscopy (TEM) is used for material characterization, while battery analyzer is used for measuring the electrochemical performance of the battery.

Development of metamaterial based low cost passive wireless temperature sensor

Wireless passive temperature sensors are gaining increasing attention due to the ever-growing need of precise monitoring of temperature in high temperature energy conversion systems such as gas turbines and coal-based power plants. Unfortunately, the harsh environment such as high temperature and corrosive atmosphere present in these systems limits current solutions. In order to alleviate these issues, this paper presents the design, simulation, and manufacturing process of a low cost, passive, and wireless temperature sensor that can withstand high temperature and harsh environment. The temperature sensor was designed following the principle of metamaterials by utilizing Closed Ring Resonators (CRR) embedded in a dielectric matrix. The proposed wireless, passive temperature sensor behaves like an LC circuit that has a resonance frequency that depends on temperature. A full wave electromagnetic solver Ansys Ansoft HFSS was used to perform simulations to determine the optimum dimensions and geometry of the sensor unit. The sensor unit was prepared by conventional powder-binder compression method. Commercially available metal washers were used as CRR structures and Barium Titanate (BTO) was used as the dielectric materials. Response of the fabricated sensor at room temperature was analyzed using a pair of horn antenna connected with a network analyzer.