Performance Characteristics of Electric Vehicle Battery using Charging Station System with Grid-Connected Configuration via Matlab Simulation

Due to the increase in demand for electric vehicles (EV) in recent years, the lack of EV charging stations and different EVs’ battery types are causing inconvenience to the user. The paper presents modeling and simulation of the grid-connected EV charging station system using MATLAB Simulink platform. The model consists of LCL filter, inverter, and battery charger. The inverter is regulated by a dq-frame that synchronizes with a phase-locked loop (PLL) to convert a three-phase alternating current (AC) source to a direct current (DC) source. Futhermore, lead acid (Pb-acid), lithium-ion (Li-ion), nickel-cadmium (Ni-Cd), and nickel metal hydride (Ni-MH) were tested and their performances were evaluated using the simulated EV charging station. All simulations were carried out and tested in the MATLAB Simulink platform. The results showed that Li-ion battery reaches the highest state-of-charge (SOC) value which is 51.66%, Pb-acid is 51.60%. Ni-MH is 51.55%, and Ni-Cd is 51.47% within 60s. The voltage values are 226.0V, 225.2V, 220.8V, and 220.2V for Pb-acid, Ni-MH, Ni-Cd and Li-ion, respectively. The findings revealed that the lithium ion is the most suitable for the use of EV since it had the fastest charging and slowest to reach its maximum threshold value of charging voltage.

Recovery of Rare Earth Metals (REMs) from Nickel Metal Hydride Batteries of Electric Vehicles

Nickel metal hydride (NiMH) batteries are extensively used in the manufacturing of portable electronic devices as well as electric vehicles due to their specific properties including high energy density, precise volume, resistance to overcharge, etc. These NiMH batteries contain significant amounts of rare earth metals (REMs) along with Co and Ni which are discarded due to illegal dumping and improper recycling practices. In view of their strategic, economic, and industrial importance, and to mitigate the demand and supply gap of REMs and the limited availability of natural resources, it is necessary to explore secondary resources of REMs. Therefore, the present paper reports a feasible hydrometallurgical process flowsheet for the recovery of REMs and valuable metals from spent NiMH batteries. More than 90% dissolution of REMs (Nd, Ce and La) was achieved using 2 M H2SO4 at 75 °C in 60 min in the presence of 10% H2O2 (v/v). From the obtained leach liquor, the REMs, such as Nd and Ce, were recovered using 10% PC88A diluted in kerosene at eq. pH 1.5 and O/A ratio 1/1 in two stages of counter current extraction. La of 99% purity was selectively precipitated from the leach liquor in the pH range of 1.5 to 2.0, leaving Cu, Ni and Co in the filtrate. Further, Cu and Ni were extracted with LIX 84 at equilibrium pH 2.5 and 5, leaving Co in the raffinate. The developed process flow sheet is feasible and has potential for industrial exploitation after scale-up/pilot trails.

Development of a Liquid Immersion-Type Nickel-Metal Hydride Battery Under High-Pressure

A nickel-metal hydride (Ni–MH) prototype battery completely immersed in an aqueous electrolyte solution of KOH under high pressure was fabricated to examine the effects of high pressure on the quality of Ni–MH batteries. The small battery cell comprised positive and negative electrode materials, as used in electric vehicles, and an Ag/AgO reference electrode. The electric capacity of the Ni–MH battery was measured at different temperatures and pressures with small currents and charge/discharge voltages of 1.6 – 1.0 V. High pressures were found to clearly and effectively enhance the electric capacity of the Ni–MH battery at larger currents. The considerable effect of high pressure on the Ni–MH battery was elucidated by the change in internal resistance during the charge/discharge cycle life experiment, indicating that the voltage of the positive electrode did not appreciably change at a high pressure compared to that of the negative electrode. Moreover, the use of large currents in rapid charge/discharge cycle tests at high pressures of up to 30 MPa resulted in charge/discharge cycles that were five times faster and a quick recovery of capacity was achieved in the 0.5 – 2.1 V range.