Powertrain 2020 - The Future Drives Electric (PDF ... - Roland Berger

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Study
But Li-Ion batteries have not completely solved the problem. The energy
density of gasoline is more than 9,000 Wh per liter – more than 40 times
that of Li-Ion batteries. The search therefore continues for the next generation
of batteries for EVs. In the meantime, we may assume that Li-Ion batteries
will be the key technology for PHEVs and EVs in the coming decade.
Other non-chemical energy storage devices include super-capacitors that
can reach very high specific power levels for a few seconds, but cannot hold
a lot of energy, and flywheels, which store energy in high-speed rotating
devices. Neither of these alternatives currently meet the requirements for
longer-distance electric driving or use in LDVs.
Below, we examine the technology used in Li-Ion batteries. We also look at
the current development focus and the costs involved.
Li-Ion battery technology
Today's Li-Ion batteries are made from a set of subsystems. Some eight
to twelve individual Li-Ion cells are put together in a stack with a basic
single-cell control system. Several stacks are then connected to make
a complete battery pack with a solid housing for crash protection, cooling
and a master control device that manages the overall system and the communication
with the rest of the vehicle.