What Is an Electric Vehicle (EV) Battery?
EV batteries are specifically designed for electric vehicles (EVs). These batteries are rechargeable and can be used multiple times, unlike single-use batteries.
Currently, lithium-ion batteries are the most popular type of EV battery, known for their light weight, high capacity, and high energy density compared to earlier lead-acid batteries. All-solid-state batteries, which eliminate the use of liquid electrolyte, are emerging as the next generation of EV batteries.
Uses of EV Batteries
EV batteries primarily power hybrid vehicles and EVs. In addition to powering EVs, they are increasingly seen as potential virtual power plants. This involves using the battery capacity of EVs to support the electrical grid during power shortages, alongside other sources like solar power and storage batteries.
Principles of EV Batteries
Lithium-ion batteries, the mainstream choice for EVs, operate by moving lithium ions between the positive and negative electrodes in a liquid electrolyte. They consist of a lithium compound organic solvent, a lithium and metal oxide cathode, a graphite anode, and a polymer compound membrane separator. Charging occurs when external power causes lithium ions to move from the cathode to the anode, creating a potential difference and storing energy.
All-solid-state batteries function similarly, with lithium ions moving between electrodes. However, they use a solid electrolyte and do not require a separator, potentially offering enhanced safety and stability.
Types of EV Batteries
EV batteries mainly include:
1. Lead-Acid Batteries
Lead-acid batteries are affordable, have a low risk of explosion or fire, and are commonly used as auxiliary batteries in EVs. They power secondary systems like air conditioners and lights, ensuring functionality even if the main drive battery fails.
2. Lithium-Ion Batteries
Lithium-ion batteries have a higher energy density compared to other rechargeable batteries, with a nominal voltage of 3.6 V. They have no memory effect and perform well at high temperatures. However, their high energy density also poses a risk of ignition, necessitating careful design to ensure safety in vehicles.
3. Nickel-Metal Hydride Batteries
Nickel-metal hydride batteries use nickel hydroxide and a hydrogen storage alloy. While they have lower energy density and performance compared to lithium-ion batteries, they are more cost-effective and safer, making them suitable for hybrid electric vehicles (HEVs).