College of Science and Technology
Permanent URI for this communityhttp://itsupport.cu.edu.ng:4000/handle/123456789/28738
Welcome to the community of research works in Science and Technology
Browse
188 results
Search Results
Item High-voltage LiNi0.5Mn1.5O4 cathodes for Li-ion batteries obtained by sol–gel combustion method: effects of fuel-type and silver doping(Sustainable Energy & Fuels, 2025-09-28) Ehi-Eromosele, Cyril O.; Ajayi, Samuel O.; Ikebudu, Jude N.; Abiaziem, Chioma V.; Mathe, Mkhulu K.High-voltage LiNi0.5 Mn1.5 O4 (LNMO) cathode materials are highly desirable for the fabrication of next-generation lithium-ion batteries (LIBs). In this study, citric acid, glycine, and sucrose fuels were used to optimize the structural and electrochemical properties of LNMO materials obtained by sol–gel combustion synthesis (SCS). The experimental results showed that the type of fuel used in the SCS process influenced the enthalpy of combustion, crystallite size, morphology, cationic disorder and electrochemical properties of the LNMO materials. XRD results indicated that all the LNMO materials have a phase-pure spinel structure with the Fd3m space group. The glycine fuel composition produced LNMO material (LNMO-G) with the least crystallite size, less cationic disorder and the highest crystallinity compared with those having the citric acid fuel (LNMO-C) and sucrose fuel (LNMO-S) compositions. As a result, the LNMO-G cell delivered the highest first discharge capacity of 115.83 mA h g−1 and retained 80.06% of its initial capacity after 200 cycles at a current density of 1C. Moreover, the LNMO-G cell had the best rate capability compared with the LNMO-C and LNMO-S cells, with a discharge capacity of 60 mA h g−1 at a rate of 2C between 3.50 and 5.30 V. Furthermore, Ag doping (LNMAO) improved the rate capability and Li-ion kinetics of the LNMO-G cathode material. The LNMAO cathode achieved a reversible discharge capacity of 100 mA h g−1 at a rate of 2C between 3.50 and 5.30 V. These findings show that LNMO cathode materials can be optimized for ultra-high-voltage (>5.0 V) performance in LIBs for advanced applications.Item Exploring layered lithium-rich spinel composite cathodes for lithium-ion battery obtained by the solution combustion-mechanochemical synthesis(Journal of Alloys and Compounds Volume 1038, 2025-08-20) Ehi-Eromosele, Cyril O.; Ajayi, Samuel O.; Shaaban, Ibrahim A.; Assiri, Mohammed A.; Hessien, Mahmoud M.; Abiaziem, Chioma V.; Sunday, Sam E.; Mathe, Mkhulu K.In this study, layered lithium-rich oxides (LLO) cathode materials were modified with different amounts of the spinel phase to form integrated layered-layered-spinel (LLS) hetero-composites [0.5Li2 MnO3 ꞏ (0.5 − x)LiNi0.5 Mn0.3 Co0.2 O2 ꞏ xLiMn1.5 Ni0.5 O4 (0.05 ≤ x ≤ 0.25)] using a facile solution combustion mechanochemical synthesis method for the first time. The XRD results indicate that all the LLS materials have distinct layered and spinel phases with R3m, C2/m and Fd3m space groups. Notably, the initial coulombic efficiency of the LLS materials increased with increase in the spinel content but showed a reduction both in their charge and discharge capacities. The LLS doped with 5 % spinel content (651LLS), exhibited the best electrochemical performance compared to the ones doped with 15 % spinel content, gave the smallest particle size and the largest unit cell volume. Consequently, the 651LLS cell delivered the highest initial discharge capacity of 279.58 mAh g⁻¹ and a capacity retention of 84.71 % after 50 cycles at a current density of 10 mA g⁻¹ within a voltage window of 2.0 – 4.8 V. Additionally, the 651LLS cell demonstrated superior rate capability with the average capacities 275, 225, 200, 155, and 90 mAh g⁻¹ at 10, 20, 50, 100, and 200 mA g−1. This enhanced performance is attributed to the optimised spinel amount and the smaller particle size which facilitated faster Li-ion transport during cycling. Also, the optimal electrochemical behaviour of the 651LLS cathode is linked to its optimum spinel content (∼5 %) which contributed to its improved structural stability. The results show that the amount of spinel in these LLS materials must be carefully tuned in relation to the operating cycling parameters to produce optimum electrochemical performance.Item Recent developments strategies in high entropy modified lithium-rich layered oxides cathode for lithium-ion batteries(ECS Meeting Abstracts, Volume MA2025-01,, 2025) Ajayi, Samuel O.; Ehi-Eromosele, Cyril; Liu, Xinying; Mathe, Mahlanyane KennethLiNi0.5Mn0.2Co0.2O2 (NMC532) is a widely used cathode material in commercial lithium-ion batteries; however, it suffers from capacity degradation and poor rate performance. In this study, sol-gel combustion synthesis (SCS) with a controlled fuel-to-oxidizer ratio (fuel stoichiometric (FS) and fuel-rich (FR) compositions, the fuel-lean (FL)) respectively, was employed to improve the structural and electrochemical performance of the NMC532 cathode. The fuel-to-oxidizer ratio was found to significantly impact the exothermicity of the combustion reaction, which subsequently influenced the morphology, crystal structure, and electrochemical performance of the synthesized NMC532 material. The FL composition produced a well-defined layered structure, the largest crystallite size, and the lowest degree of cation mixing compared to the FS and FR compositions. The FL cell exhibited an initial discharge capacity of 180 mAh/g and the highest capacity retention of 92.2% when cycled at 0.1 C within a voltage range of 2.5–4.4 V. Additionally, it demonstrated superior rate capability, delivering capacities of 180, 178, 175, and 173 mAh/g at current densities of 1 C, 3 C, 5 C, and 10 C, respectively, within a voltage range of 3.0–4.6 V. The electrochemical impedance spectroscopy (EIS) measurements confirmed that the FL cell had the lowest polarization and impedance. The superior electrochemical performance of the FL cathode was ascribed to its improved structural properties.Item Recent developments strategies in high entropy modified lithium-rich layered oxides cathode for lithium-ion batteries(Inorganic Chemistry Communications, 2025-02) Ajayi, Samuel O.; Dolla, Tarekegn H.; Bello, Ismaila T; Liu, Xinying; Makgwane, Peter R.; Mathe, Mkhulu K.; Ehi-Eromosele, Cyril O.Lithium-rich layered oxides (LRLOs) are of intense interest and are regarded as one of the best cathodes for next-generation Lithium-Ion batteries (LIBs). LRLOs are favored due to the low cost of production, high energy densities, voltage, and specific capacity. LRLOs suffer from irreversible capacity loss, poor rate capability, voltage, and capacity fade, which in turn limit their full practical applications and commercialization. Therefore, strategies such as surface coating, surface treatment, composition optimization, and elemental doping have been explored to enhance the structural and electrochemical performance of LRLO. Nevertheless, high entropy (multiple elements) doping has proven to be a very effective strategy due to its simplicity and expansion of LRLO lattice interplanar spacing without damaging their original structure. It is worth noting that there has been little research work on high entropy strategies for modifying LRLO cathode. Thus, the aim of this review is current update on high entropy strategies for modifying LRLO cathode materials.Item Environmental assessment of radionuclide exposure in packaged borehole water exploited from crystalline rocks in Ogbomoso(ICSAEES-2024, Lagos, Nigeria, 2024) Oladipo, A. E.; Aremu, A. A.; Adeniji, A. A.; Ayinla, T. O.; Babarimisa, I. O.; Morakinyo, R. O.; Araka, I. O.; James, U. E.The amounts of naturally occurring radionuclides (40K, 238U and 232Th) in packaged borehole water manufacture have been investigated in this work. Furthermore, the buildup of radioactive materials in drinking water presents a direct path for human population exposure to internal radiation. The amount of radioactivity in the processed and unprocessed water samples was measured using gamma spectrometry and a computer-resident quantum multichannel analyser (MCA 2100R) connected to a well-calibrated and shielded NaI (Tl) detector. From the results, it was revealed that the values of activity concentration of processed water ranges between 50.46 ± 3.14 Bq/L to 102.18 ± 14.07 Bq/L, 7.92 ± 4.46 to 16.71 Bq/L, and 10.00 ± 0.84 Bq/L to 14.87 ± 4.03 Bq/L for 40K, 238U and 232Th, respectively. Also, the results obtained for the activity concentration of unprocessed water ranges between 74.51 ± 3.51 Bq/L to 102.21 ± 7.23 Bq/L, 14.86 ± 1.91 Bq/L to 19.87 ± 3.10 Bq/L and 10.00 ± 3.36 Bq/L to 17.79 ± 4.43 Bq/L for 40K, 238U and 232Th, respectively. The results confirmed the presence of40K as a principal occurring radionuclide in the water samples. The annual effective dose for processed water ranges from 0.012 to 0.017 mSyr-1, while it ranges between 0.015 and 0.020 mSyr-1 for unprocessed water. Results in the present study fall below 0.1 mSyr-1, which is the acceptable limit recommended by International Commission on Radiological Protection standard value.Item Effects of Aerosol Scattering Attenuation on Free-Space Optical Link Performance in Owerri, Southeast, Nigeria(Science and Technology: Developments and Applications Vol. 8,, 2025) Akinwumi, A.; Ayo-Akanbi, O.; Omotosho, T. V; Arijaje, T; Ometan, T.; Adewusi, O.High-speed, point-to-point data transmission through laser beams across terrestrial networks is sometimes referred to as "Free-Space Optics" (FSO). Multimedia applications including social networks, OTT platforms, video conferencing, and multimedia streaming are driving up the demand for data rates and channel bandwidth, which has led to a telecommunications bottleneck. In spite of the several benefits of using free-space optical (FSO) communication systems as complementary platforms for next-generation networks, the existence of atmospheric disturbances such as fog and scintillations are key sources of signal impairment that affect system performance. Thus, it is crucial to learn about the specific weather patterns of the areas where FSO lines will be installed. The purpose of this work is to estimate the availability performance of FSO lines broadcasting at both 850 nm and 1550 nm by performing a statistical analysis of meteorological visibility data gathered for Owerri in Nigeria over a 21-year period (2000-2021). The results show that the visibility during the most common fog events in Owerri is 100 meters. The probabilities of encountering and exceeding the scattering attenuations associated with Owerri's most common fog event are 0.0002 and 0.0229, respectively. This research could be expanded in the future by exploring the effects of varying localized climatic conditions on the many forms of optical signals, such as plane, spherical, and Gaussian beam waves. This would aid in the modelling of different forms of attenuation for deployment sites of FSO or hybrid FSO systems.Item Analysis of Attenuation Due to Atmospheric Gases Prediction Models at Ota, Nigeria(Science and Technology: Developments and Applications Vol. 7, 2025) Akinwumi, A.; Omotosho, T.; Usikalu, M.; Adewusi, M.; Ometan, O.; Emetere, M.The theory explaining the interaction between molecules and radiation of gases in telecommunication ascertained the fact that microwave signals experience significant attenuation that can appreciably degrade the quality of signal transmissions. Millimeter and sub-millimeter wave signals experience scattering and absorption while propagating through the atmosphere. The demand for satellite services is rapidly increasing on a daily basis. One of the major concerns for satellite telecommunication designers is the impacts of gas attenuation on earthspace path links, most importantly in tropical areas. This research has been directed at the analysis and comparison of gas attenuation prediction models at Covenant University, Ota, southwest Nigeria (Lat: 6.7 o N, Long: 3.23o E). Gas attenuation data were collected from the spectrum analyzer and Davis automatic weather station for a period of five years (April 2012- December 2016) from Astra 2E/2F/2G Satellite link set at an elevation angle of 59.9o on 12.245 GHz. The monthly gas attenuation was analyzed and compared with existing gas attenuation prediction models that could provide a guide to microwave propagation engineers in the tropical region. The results suggest that even during clear-sky, gas attenuation still poses a threat to the design of satellite communication on the earth-space path. The results also suggest that even during clear-sky, gas attenuation still poses a threat to the design of satellite communication on the earth-space path. Likewise, the same pattern was observed from 2013 to 2016 where Salonen’s model was reported as the lowest model and Liebe’s model gave the highest value. Therefore, the ITU-R model may be more accurate for modelling gas attenuation for the region. Hence, the statistics provided in this work will help engineers in planning and designing good telecommunication systems in the tropical region.Item Environmental Impact of Pre-occupational radon level measurements in medical imaging facilities of a tertiary hospital in south-west Nigeria(ICSAEES-2024, Lagos, Nigeria, 2024) Aremu, A. A.; Oni, O. M.; Oladipo, A. E.; Oladapo, O. O.; Obafemi, Y. D.; Oniha, M. I.; Babarimisa, I. O.; James, U. E.Radiation facilities are placed in an enclosed environment to prevent scattered radiation from getting out of the room, by so doing the rooms foil gas exchange from the outdoor environment, thereby increasing the radon concentration in the indoor air. This study aimed at estimating the occupational radon exposure level in medical facility room in order to estimate the radiological risk in such environment. RAD7 electronic device was used to measure theindoor radon concentration in the five proposed roomsin the newly built Radiology department of a University Teaching Hospital while a digital thermometer was used to measure the ambient temperature. The radon concentrations ranged between 12.09Bq/m3and 58.52 Bq/m3. The ultrasound room has the least average value of 12.09 Bqm-3 and the Fluoroscopy room has the maximum average value of 58.52 Bqm-3. The radon level translated into the effective dose, working level and excess life-time cancer risk for any worker staying for a period of nine hours per day, over a year. Fluoroscopy facility was estimated to present the highest annual absorbed dose and annual effective dose with 0.73 mSvy-1 and 0.8858 mSv y-1, respectively.The mean radon concentration for the five rooms was 41.96Bq/m3. The calculated annual effective dose rate and the mean annual absorbed dose rate to the lung within the radiation facilities rooms were 0.529 mSvy- 1and 0.6350 mSv y-1, respectively.The indoor radon concentrations measured and the effective dose value of 200 Bq/m3 and 1 mSvy-1 respectively is below the reference limitset by International Commission Radiation Protection (ICRP) Agency.This implies that the radiation facility rooms are in conformity with international best practices and this is in agreement with SDG 3 (Good Health and well –being)Item Construction of an Arduino Based Smart Energy Meter(ICSSD 2024, 2025) AKINWUMI, Sayo A.; Braide, S. M.; Arijaje, T. E.; Akinwumi, O. A.The design of a smart energy meter with an arduino that measures the current, voltage, energy and power by an individual or small organization is very important. Electricity is among the basic requirements for the maintenance of life contents. But in our country, we have many localities where they have constant electricity and others with little or no access to electricity. Consumers are dissatisfied with the services been provided by the electricity company, and the absurdity in monthly bills are the most common source of displeasure. The issue of having outrageous bills despite the lack of electricity, the ignorance of how much voltage and current is being used in homes led to this creation of this project. This focuses on the system’s problem which entails workforce, time consumption and manipulations of readings by an official authority while producing the bill to the consumer. This project consists of the following components Energy Meter, Arduino DANO Board, Global System for Mobile Communications (GSM) Module, Capacitor, Mobile Phone, Load, Current sensor acs712, Voltage sensor, Transformer, Vero Board, and liquid crystal display (LCD). The energy meter continually monitors the readings and the Arduino processes this data and the readings are uploaded on the liquid crystal display (LCD) of the device and when the readings are taken the Global System for Mobile Communications (GSM) module posts the readings to the thingspeak on the mobile phone. The constructed device displayed the energy, power, current and voltage been consumed with varying loads used and the readings were uploaded on the platform used (thingspeak). The results shows that at 153 W it was at its highest point and at 132 W it was at the lowest point when plotted with time. From the results, it shows that the device is working perfectly. There was fluctuation in the power, voltage and currents but constant increase in the energy. Asides from the saving of cost in relation to remote reading of meters, it is hoped that implementation will encourage energy efficiency and raise awareness of energy consumption and demand side participation in the national energy market. This project is recommended for the electricity power company (PHCN) and it is also recommended for individuals that reside in some localities because it would help save cost and it is convenient.Item Eco-friendly Weather Monitoring Device using Arduino Mega and Sensor Integration(ICSAEES-2024, Lagos, Nigeria, 2024) AKINWUMI, Sayo A.; Okey-Amadi, O.; Ayara, W. A.; Akinwumi, O. A.The project involved the construction of a hardware setup, utilizing the Arduino Mega as the central control unit. The BME280 sensor was employed to monitor temperature, humidity, and atmospheric pressure, providing comprehensive weather data. The SGP30 sensor was utilized for analyzing air quality, detecting various pollutants such as volatile organic compounds (VOCs) and carbon dioxide (CO2) levels. The MQ135 gas sensor enabled the detection of harmful gases, including ammonia, nitrogen dioxide and benzene. The integration of a 16x4 LCD display allowed for real-time visualization of the collected weather data, providing users with immediate insights. Tactile switches, along with 10k ohm resistors, were used for user interaction, enabling menu navigation and system control. The DS1302 RTC module facilitated accurate timestamping of data readings, while the SD card module enabled data logging for long-term analysis and storage. The successful construction of the Weather Monitoring System demonstrated its capabilities in terms of accuracy, reliability, and real-time monitoring. The integration of Arduino Mega, along with the BME280, SGP30, MQ135, LCD display, push buttons, 10kohm resistors, DS1302 RTC module, and SD card module, provided a comprehensive solution for weather data collection, analysis, and visualization. This project contributes to the advancement of weather monitoring systems, emphasizing the importance of Arduino-based solutions and sensor integration. It highlights the potential for utilizing such technology to address weather challenges effectively, enabling datadriven decision-making and fostering weather awareness. Overall, the Weather Monitoring System presented in this project report offers a valuable tool for monitoring and analyzing atmospheric conditions, paving the way for future enhancements and applications in various weather monitoring domains.