Unlike conventional petroleum driven internal combustion vehicle, Electric Vehicle is propelled by a large electric motor, which is powered through a rechargeable onboard battery system.
While most of Electric Vehicles production models utilize one type of battery(Lithium ion), there are several different types of batteries that have been implemented in battery electric vehicles:-
1. Lithium-Ion Batteries
In the early 1990s Lithium batteries came into the commercial, holding an elevated energy density. Unlike most batteries, these are unlikely to lose their charge when not being used. This is a feature called self-discharge.
- Excellent specific energy (140 Wh/kg) and energy density
- Low self discharge rate (5% per day) which is much lower than Nickel Metal Hydride & Lead Acid batteries
- Good high-temperature performance
- Lighter and smaller in size in comparison to others for same battery size
- Very high cycle life (6000 cycles)
- Almost negligible maintenance cost and easily recyclable, hence more reliable
- More expensive
- Major safety concerns regarding the overcharging & overheating as it can experience a thermal runaway, which can trigger vehicle fires or explosions, if not taken care.
Types of Lithium ion batteries:-
1. LCO: Lithium Cobalt Oxide
Popular choice for mobile phones, tablets, laptops and digital cameras.
2. LMO: Lithium Manganese Oxide
Used for power tools, medical instruments as well as hybrid and electric vehicles.
3. NMC: Lithium Nickel Manganese Cobalt Oxide
Choice of power tools, e-bikes and other electric powertrains.
4. LFP: Lithium Iron Phosphate
Applied to maintain full charge level and prevent sulfatation on lead acid batteries.
5. NCA: Lithium Nickel Cobalt Aluminum Oxide
Applied on medical devices, industrial & electric powertrains.
6. LTO: Lithium Titanite
UPS, electric powered train & solar powered street lighting
2. Nickel-Metal Hydride Batteries (NiMH)
These came into commercial use a little earlier in the late 1980s. These are used routinely in computer & medical equipment and in some Hybrid Electric Vehicles as they offer reasonable specific energy and specific power capabilities.
- Specific energy (68 Wh/kg),which is double compared with lead acid batteries.
- Much longer life cycle(5-7 years) than lead-acid batteries though lesser than Lithium ion batteries
- Low charging efficiency
- High Self-discharging rate up to 12.5% per day at room temperature which is even elevated at higher temperatures
- Generation of heat during fast charging & discharging.
3. Lead-Acid Batteries
These are the oldest type of battery, formulated in 1859 and still being used. They are recyclable. They hold a mild solution of sulfuric acid and are a kind of wet cell battery. These batteries are only used in commercially available electric-drive vehicles for ancillary loads.
- No danger of under or over-charging and a high level of operating safety due to tray insulation.
- Poor specific energy (34 Wh/kg)
- Short Cycle life (700 cycles)
- Poor cold-temperature performance
- Heavy as it is made from Lead
Having excellent specific energy and low self-discharge rate, it appears that variants of Li-ion batteries are now the dominant type that are currently used in Battery Electric Vehicles.
Meanwhile, lead acid and NiMH batteries no longer appear to be appropriate for the use, though these batteries are still frequently used in the automotive industry.