Shift Magazine - November 25, 2019 - 27

In the next several years, we really
think that liquid cooling - basically
your glycol-water-mix cooling
plate - I think that's going to be the
predominate way to cool it.

Sanjay Misra, senior scientific principal at Henkel

From top: Donaldson's dual-stage battery
vent family; Gore's low-pressure vent;
NeoGraf's heat-spreading material

fast-charging can cause batteries
to get so hot that the cells get
damaged.
"People expect their vehicles
to regain range relatively quickly,"
Nicgorski said. "Fast-charge is limited partially by how well we can
thermally manage the battery."
If the cells heat up too much, they can initiate
the same reaction in adjacent cells, causing a
domino effect, or "propagation" reaction.
That's thermal runaway.
Some suppliers are looking at venting as an answer.
Gore Automotive Products created
a low-pressure evacuation vent for battery packs, which uses a flexible, waterproof membrane that expands and releases
extra pressure that occurs from overheating.
Donaldson Co.'s dual-stage battery vent first equalizes pressure while preventing contaminants from entering the battery,
then expels heat and gas from inside the battery cell quickly and
in a controlled direction.

DIFFERENT APPROACHES

DuPont's approach to thermal management includes cell-to-cell
insulation separators, preventing propagation of heat from the
initial cell to the neighbor cell, and lightweight, thermal insulating
flame barriers.

Some suppliers are examining
alternate battery-pack materials.
NeoGraf Solutions recommends using heat spreaders that
are made of graphite, rather than
aluminum, to cool the cells more
quickly.
"Going to graphite, you can
help battery-pack manufacturers meet their goals:
their fast-charge goal, their cell lifetime goal,
their miles-per-charge goal and whatever
safety anti-propagation goal they have,"
said applications engineering manager
Bret Trimmer.
For all of these solutions, thermal
management comes down to improving
EV safety, range and the driver experience.
"The message is to implement the thermal
systems which enable the fast-charge that the users
expect for the vehicle to meet their needs," Nicgorski said.
But Denise Gray, CEO of LG Chem Michigan Inc. Tech Center,
cautions that the industry is still in the early stages of solving the
thermal management problem.
"I still want to push for more innovation in that area," Gray said
at the Shift event.
She said that includes looking at the issue from a cell chemistry perspective. "What are the chemistry tricks we can do to
make it more thermally resistant, if you will? ... I'm looking for
that next, next technology." n
november 2019 * shift

Shift Magazine - November 25, 2019

Table of Contents for the Digital Edition of Shift Magazine - November 25, 2019