Electric Vehicle Energy Storage: Performance Comparison of Various Energy Storage Devices
Previously, lead-acid batteries were the most widely used power source in electric vehicles. However, with the development of electric vehicle technology, lead-acid batteries have been gradually replaced by other types of batteries due to their lower energy density, slower charging speed (relatively speaking), and shorter lifespan. Nickel-cadmium batteries are mainly used in power tools or electric forklifts and have not been used in electric vehicles.
Energy storage devices include two types: chemical energy storage devices and physical energy storage devices.
1. Chemical energy storage devices: These include nickel-metal hydride batteries and lithium-ion batteries. Sodium-sulfur batteries and fuel cells have not yet been realized.
2. Physical energy storage devices: including supercapacitors and flywheel batteries; superconducting energy storage is mainly used in power supply control departments.
Generally, electric vehicles (EVs) are powered by batteries, which undergo frequent, shallow charge-discharge cycles during operation. During these cycles, voltage and current can fluctuate significantly. Given these characteristics, EV power systems place several specific requirements on batteries: EVs require batteries with higher specific power; EV batteries must have high charge-discharge efficiency (crucial for ensuring overall vehicle efficiency); and EV batteries should maintain relatively stable performance under rapid charge-discharge and varying operating conditions.
Electric Vehicle Energy Storage: Emissions Performance
The pollution from electric vehicles primarily stems from the source of the electricity used to charge them. Only by considering both the location where electric vehicles are used and the source of the electricity used to charge them can one determine whether using electric vehicles is less polluting than using internal combustion engine vehicles. Electric vehicles charged using clean energy sources (such as hydropower) produce very little pollution, while those charged using unclean energy sources (such as coal or oil) produce more pollution than internal combustion engine vehicles. Power sources in most areas fall somewhere in between. Because they are not intended for use in all locations, electric vehicles have the potential to make their pollution significantly lower than that of internal combustion engine vehicles.
Pure electric vehicles (vehicles) emit zero emissions during operation. However, emissions occur at power plants that convert raw energy into electricity. Therefore, the emissions of electric vehicles depend on the emissions from local power plants. Some researchers believe that switching to electric vehicles in areas where electricity is supplied by coal-fired power plants could increase emissions of sulfur oxides (SOx) and particulate matter (PM), and potentially increase carbon dioxide (CO2) emissions.
