If you are familiar with electric buses, you have likely heard of lithium-ion batteries - the preferred battery type and chemical composition for electric buses, and the backbone of electric buses today. However, many people only know that lithium-ion batteries are related to EVs, but do not know more details - so why are lithium-ion batteries so important to electrification? How are they used throughout their lifespan?
Lithium (Li) is the third element on the periodic table. Although not as rare as precious elements like gold, lithium is relatively scarce, accounting for less than 0.0001% of the earth's crust. Lithium-ion batteries have a high energy density, making lithium ions an ideal chemical component for portable storage.
In the 21st century, lithium can be found in almost all devices that require electricity but are not connected to the grid. Wireless power tools, laptops, smartphones, and most rechargeable devices use lithium-ion chemistry. These batteries are also used in electric buses - as the next major development in transportation and sustainability for the coming decades as the world seeks to reduce transportation carbon emissions.
It is important to note that manufacturing battery electric buses can consume a significant amount of energy, partly due to energy-intensive battery manufacturing processes. However, unlike diesel or gasoline vehicles, once they leave the factory with the battery and electric bus or truck, they no longer emit greenhouse gases (GHG). From that point onwards, these vehicles gradually approach zero carbon emissions. In other words, the longer they travel, the more greenhouse gas emissions they reduce compared to using internal combustion engine vehicles.
As the world continues to shift towards cleaner sources of energy, these benefits become even more apparent. With the development of lithium recycling technologies and achieving 100% recycling rates, the manufacturing of electric buses will become even cleaner.
The average lifespan of lithium-ion batteries for electric buses is estimated to be 20 years, while that of petroleum-fueled vehicles is estimated to be 13 years. However, did you know that the battery may not be actively used in the vehicle throughout its entire lifespan?
The lifespan of a battery is divided into four usage stages, determined by the change in the battery's energy capacity and performance over time.
The battery's lifecycle begins in the usage stage, which is the period of time when it will be actively used in the vehicle once assembled into modules and larger battery packs (the primary storage medium for lithium-ion batteries for electric buses).
During this period, the battery's main purpose will be to charge and power the electric bus on its zero-emission route, and of course, drive the vehicle's propulsion system during each trip. Thermal management through liquid cooling systems and advanced battery management is crucial to its health.
Battery technology is rapidly advancing each year. Once the energy capacity of the battery decreases slightly, there will be newer and higher-capacity batteries available, at which point the battery enters the arrangement stage of its lifecycle.
When the energy capacity of the battery decreases to a level where it is no longer usable and arrangable, it will be taken out and sent to a battery energy storage facility for static energy storage with light load demands.
The battery remains highly useful at this stage and can result in extensive savings through off-grid energy storage, such as distributing energy collected from renewable sources like V2G or solar panels and wind turbines for the energy cost savings of electric vehicle owners/operators.
This energy can be returned to the grid during high electricity demand or economically used to recharge another vehicle.
Lastly, when the useful energy capacity of the lithium-ion battery for electric buses has diminished due to degradation and is no longer usable, after several decades, it will be recycled. As of now, we can recycle 95% of battery materials. But as mentioned earlier, within the next 10 to 15 years, we will be able to achieve 100% battery material recycling.