While electronic capabilities double on an annual basis,
battery energy density grows at only 12 percent. This
divergence in capabilities creates a widening gap between
energy sources and the devices they power: Many lithium-based storage technologies add a second dilemma as
we desire more capacity in smaller forms while fearing
the consequences of carrying the equivalent of a flask of
gasoline in our pocket.
Many users also experience runtime anxiety, a feeling
made worse by the relatively slow charging rates of today’s
batteries. Our long wait for the juice that powers our
devices is a symptom of the battery itself, in that modern
electrochemical batteries lack the power capability not only
to absorb power but also in their ability to deliver it.
As batteries shrink, the resistance that limits their ability to
deliver energy at high rates will tend to increase. This is to
say nothing about the limited temperature range and cycle
life to be expected. As for safety concerns, “Please remove
your batteries from checked baggage; Thank you”.
Maybe a better battery isn’t a battery at all.
Supercapacitors offer a high-capacity alternative to lithium
batteries in that they are power efficient, operate over a
wide temperature range, have long cycle lives and, most
importantly, are safe.
A critical comparison shows that although the energy
density of Li-Ion is ten times greater than a hybrid
at 35 Wh/L, the Li-Ion
battery’s power delivery
capability is less than
one tenth that of the
typically at 1 k W/L or
Though not obvious,
this power advantage
helps on both the
charge and discharge
side of the equation.
properties limit the
charge time to hours while the supercapacitor can be
refreshed and discharged in seconds.
Supercapacitors are stepping up to the challenge of
providing cleaner, higher-power, energystorage devices.
The beauty of a supercap as a power source is that, as it
transfers and stores a charge, an electrostatic or physical
effect takes place, rather than a chemical reaction as occurs
in a battery. Because that physical effect is reversible,
a supercap can charge and discharge quickly, over and
over again. But energy storage is directly proportional to a
supercap’s capacitance, which, in turn, is proportional to its
plate or electrode surface area to which charging particles
cling. Electrode surface area also determines current-carrying capability.
Manufacturers are steadily increasing supercapacitors’
energy density with new nanomaterials that enlarge
electrode surface area and thus boost their ability to hold an
These advances in materials science/production methods
and a thinner form factor for an optimal physical fit are
enabling supercaps to become a cost-effective complement
to batteries in peak power management and energy storage
Integrated battery/supercap systems can deliver better
efficiency and improved peak load response at all levels
from embedded electronics in portable devices to grid-level
Nanomaterials Extend Charge-Carrying
Because a supercap’s ability to hold a charge per
unit weight has been small, it’s been a niche player until
now. But new materials are adding energy density to a
supercap’s technical advantages – high power density,
In 1965, Gordon Moore’s prediction could not anticipate the mobile xplosion in electronic products
and the consequences it would have on
energy storage requirements.