Over the last two decades, lithium-ion battery technology has worked its way to the forefront of the automotive market. These batteries enable automakers to redefine consumer and commercial transportation by reducing or eliminating the need for fossil fuels in internal combustion engines (ICE). But electric vehicle (EV) battery technology continually pushes the bounds of lithium-ion batteries' ability to provide ample power, longevity and safety.
We'll highlight some of the current EV battery technology on the market today and analyze the varying battery cell sizes at work in different EV systems.
Types of Electric Vehicles
Popular EV manufacturers like Tesla, Honda, BMW, Ford and Porsche create diverse and innovative EV cars that utilize lithium-ion battery tech. Fully battery-powered electric vehicles (BEV) rely exclusively on electric power to drive, while plug-in hybrid electric vehicles (PHEVs) and full hybrid electric vehicles (FHEV) work in tandem with ICEs to generate and provide power. All these vehicle types require different levels of battery complexity and size.
1. Full Battery Electric Vehicles (BEV)
Tesla, currently the largest global EV manufacturer, creates vehicles with up to 110kWh battery systems. These cars can store enough energy to power a standard 60W light bulb for over 76 days and power the Tesla Model S for 400 miles. Their newest battery pack will likely contain several thousand of Tesla's very own 2170 lithium-ion cells.
The 2170 Tesla lithium-ion cells are 10-15% more energyefficient than the Panasonic 18650 cells at work in previous models. Tesla's 100kWh battery solution, built around the 18650 cell, contains 8,256 cells (12Ah/cell), evenly distributed across 16 battery modules. This cell can pilot the Model S over 300 miles.
The new Porsche Taycan―Porsche's response to Tesla's high-performing EV, the Model S Performance―contains a 93.4kWh battery that produces 800V, instead of the standard 400V found in most other electric vehicles. The Taycan's battery consists of 33 battery modules with 12 cells each, totaling 396 lithium-ion cells capable of storing a whopping 235.8 Wh/cell. Since battery charging speed is limited by current, the higher voltage these cells produce means lighter battery system weights and faster charging. However, this high-power battery system presents unique design challenges and requires more advanced power conversion and current protection for running subsystems throughout the vehicle.
2. Plug-Ins and Full Hybrids
Toyota's most popular PHEV, the Prius Prime, boasts an 8.8 kWh battery pack, which enables the vehicle to achieve nearly 55 MPG in the city. Drivers can charge the 8.8 kWh battery at home or on the go, and because the Prius Prime consumes more electricity than gasoline, it saves money at the pump. The Prius Prime is powered by five battery stacks, each containing 19 LI cells (95 cells) that combine to a total capacity of 8.8kWh. By comparison, the standard Prius― the world's most popular FHEV―contains a much smaller battery, with only two stacks at 28 cells each (total of 56 cells), giving it a final capacity of 0.745 kWh. Notably, the energy densities of the PHEV and FHEV are 92.6 Wh/cell and 13.3 Wh/cell, respectively. The larger, more energy-dense battery is ideal for powering higher workloads throughout the vehicle, making the Prius Prime more dependent on electrical energy than the standard Prius. Many other manufacturers offer multiple models with varying battery capacity systems and battery utilization.
EV Battery Management Systems: Speed, Safety & More
Different EV vehicles demand different battery capacities, but EV batteries differ in much more than capacity. When designing EV battery systems, engineers also consider charging speed, charge cycle-ability, degradation, chemistry and, of course, safety. Energy and power density thresholds have been realized in most EV applications, yet vehicle manufacturers are constantly tweaking module and cell sizes for optimum performance levels.
Regardless of lithium-ion battery cell and module sizes, the high-voltage battery systems that power EVs require meticulously designed battery management systems (BMS) to ensure maximum power and safety. BMS technology and key component manufacturers such as Silicon Labs and Pulse Electronics are critical in advancing electronic vehicle battery technologies and lithium-ion cell and module production across the EV industry.