Three Types of Electric Vehicles Batteries
Considering the divergent paths the transportation and automobile industries are taking away from fossil fuels, electric vehicle batteries are arguably one of the most important technological components of the decade. The batteries themselves are composed of cells, the efficiency and performance of which can vary based on how they are manufactured.
One of several different battery types may be used by any of the EVs that you come across. As someone who may potentially be servicing these vehicles, it stands to reason that you should be familiar with the components that deliver power to them. In this article, we’ll examine the three most important electric vehicle battery cell types and how they differ from one another.
1. What is a Cylindrical Cell?
Cylindrical cells are lithium-ion batteries that are encased in rigid, cylindrical casings. Given their shape and minimal footprint, these cells are ideal for stacking and installation in all manner of housing configurations. What’s more, the unique shape of the casing means that they are far less prone to swelling, a dangerous side effect that occurs when gasses accumulate within the casing. Additional benefits include:
- Cost – In the EV battery world, cylindrical cells are considered a “mature” technology, meaning that they have been in use for a number of years. While a long life has proven them to be reliable, it also means that the cost to manufacture these cells has come down considerably.
- Heat dissipation – The design of cylindrical cells allows heat energy to dissipate easily, which makes them less likely to overheat than other cell types. This in turn translates into an overall longer battery life.
- Can be combined in series and parallel - Concerning reliability, cylindrical cells may give other battery types a run for their money – configuring the cells in series and in parallel, in the event one of the cells becomes inoperable, the impact on the performance of the vehicle will be minimal. Conversely, a damaged cell in a prismatic cell battery could comprise the performance of the entire battery pack.
Cylindrical cells are not without their disadvantages; after all, this type of battery has been manufactured and in use for the better part of two decades. Here a just a few:
- Lower output – The design that makes cylindrical cells easily stacked and installed is the same design that limits the amount of power that they can deliver. For this reason, smaller vehicles that require smaller batteries often lean towards using prismatic and even pouch cell batteries.
- Weight – Many cylindrical cells are housed within a steel casing. While that does improve the overall safety of the battery, it also adds significant weight to the vehicle. When it comes to powering EVs, lighter is better.
2. What is a Prismatic Cell?
Many argue that prismatic cells will soon dethrone cylindrical cells as the battery type of choice within electric vehicles. Unlike cylindrical cells, prismatic cells are typically rectangular in shape and are stacked in columns when arranged within the vehicle. They offer a greater power output than cylindrical cell batteries and perform better in low temperatures. While this might not be a great selling feature in places where temperatures remain moderate year-round, it is something that should be considered further away from temperate zones where the vehicle is expected to operate. Additional benefits include:
- Higher efficiency – Prismatic cells deliver greater power in a smaller casing. This also means that as electric vehicles are designed to be increasingly lightweight, manufacturers can leverage the smaller size of prismatic cells to power the vehicle over longer distances.
- Improved resistance – The internal resistance of prismatic cells is somewhat better than other battery types, which makes them a good fit for applications that require the maximum amount of power.
- Safety – The interior of a prismatic cell consists of winding or laminated technology which offers superior protection of the cell.
- Enhanced power storage – Prismatic cells can store greater amounts of energy relative to their volume simply because less housing material is required compared to cylindrical cells.
Prismatic cell batteries are still more expensive to manufacture than cylindrical cell batteries, a factor that is perhaps second only to efficiency and performance when it comes to importance. Unfortunately, cost is not the only disadvantage of the prismatic cell:
- Difficult in manufacturing standardization – The fact that the size of the prismatic cells can be customized based on the size of the device it is intended for will arguably lead to a great many different variations of the cell. This will pose a challenge when it comes to perfecting the manufacturing process.
3. What is a Pouch Cell?
Pouch cells are manufactured to deliver greater power than other battery types. Unlike cylindrical and prismatic cells that employ rigid casings, pouch cells, as the name implies, use soft plastic casings.
- Maximizing space - The plastic pouch design is beneficial because it allows the designer to maximize the space within the vehicle’s battery compartment.
- Low cost and low yield - Pouch cell batteries are advantageous because they are relatively low-cost and yield a very high power density.
- Lower resistance - Unfortunately, the soft plastic design of the casing, while good for maximizing space, does little in terms of offering enhanced resistance. In fact, pouch cells have drastically lower resistance than other batteries. To counteract this, additional supports need to be added during battery installation to prevent mechanical damage to the cell.
- Reduced lifespan - Pouch cells generally have a lower life span relative to prismatic cells.
Will the Future Reveal Additional Battery Types?
While the three battery types listed above are the most viable options for today’s electric vehicles, new battery types like solid state and liquid air batteries are currently under development and promise greater power, reduced charge times, and lower cost.
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