Evaluating the Adequacy of laboratory facilities on students’ academic Performance in Secondary School in Calabar, Nigeria

Abstract

Currently, the energy storage systems for hybrid electric vehicle (HEV) are high power-type lithium-ion batteries and super capacitor (SC). In this paper, three commercial high power-type lithium-ion batteries of different electrode materials including Li4Ti5O12 (LTO), C/LiMn2O4 (LMO), C/LiFePO4 (LFP), and a commercial SC are investigated and compared to each other. Through a series of different charge rate currents and discharge rate currents test and the hybrid pulse power characteristics (HPPC) test at different working temperature, the power characteristics, rate capabilities, thermal performance and energy density can be comprehensively compared and evaluated. Test results show that the performance under low temperature and the specific power of the LMO and LFP battery are inferior to those of LTO battery and SC. The specific power of the LFP cell and the LMO cell only account for 49% and 63% of that of LTO cell under room temperature, respectively, but the specific energy are 120% and 190% of the LTO cell, respectively. According to the open circuit voltage-state of charge (OCV-SOC) curves, 1mV voltage measurement error would cause about 3% SOC estimation error for the LFP cell but the others batteries' SOC estimation are less than 0.5%, which means that LFP cell requires higher cell voltage measurement precision for the battery management system (BMS) than others type of type of battery. SC cell has excellent specific power, and its performances are almost not depend on the discharge or charge current rate and the working temperature, however, its specific energy is very low. Therefore, when matching hybrid electric vehicle powertrain with SC, the main consideration is that the total energy of SC must meet the requirements of HEV accelerating and regenerative braking, while, matching the HEV powertrain with battery, the power of the battery is the main consideration.