The Important Information/Disclaimer is incorporated in the catalog where these specifications came from or

available online at www.avx.com/disclaimer/ by reference and should be reviewed in full before placing any order.

1

INTRODUCING BESTCAP®: A NEW GENERATION OF PULSE SUPERCAPACITORS

Supercapacitors (also referred to as Electrochemical Capacitors or

Double Layer Capacitors) have rapidly become recognized, not only as an

excellent compromise between “electronic” or “dielectric” capacitors such

as ceramic, tantalum, film and aluminum electrolytic, and batteries (Figure

1), but also as a valuable technology for providing a unique combination

of characteristics, particularly very high energy, power and capacitance

densities.

There are, however, two limitations associated with conventional

supercapacitors, namely: high ESR in the tens of Ohms range, and high

capacitance loss when required to supply very short duration current

pulses. BestCap® successfully addresses both of these limitations.

The capacitance loss in the millisecond region is caused by the charge

transfer (i.e. establishment of capacitance) being carried out primarily by

relatively slow moving ions in double layer capacitors.

In the above-mentioned “electronic” capacitors, the charge transfer

is performed by fast electrons, thereby creating virtually instant rated

capacitance value. In the BestCap®, a unique proton polymer membrane is

used – charge transfer by protons is close to the transfer rate for electrons

and orders of magnitude greater than organic molecules. Figure 2 below

illustrates the severe capacitance loss experienced by several varieties of

supercapacitors under short pulse width conditions. It can also be seen

from Figure 2 how well BestCap® retains its capacitance with reducing

pulse widths.

For comparison purposes, the characteristic of an equivalent capacitance

value aluminum electrolytic capacitor is shown in Figure 2. The electrolytic

capacitor is many times the volume of the BestCap®.

Figure 1. Specific Energy of Capacitor Types

ELECTROLYTIC

CAPACITOR

PO

LYMER

ELECT

ROL

YTIC

ALUMINUM

TAN

TAL

UM

100

10

1

1000

100

10

1

0

0

0

0

1

1

.

0

1000

10000

SPECIFIC ENERGY

Capacitance (mF)

®

0%

20%

40%

60%

80%

100%

1000

100

Pulse Width (msec)

1

0

1

EDLC-Electrochemical

double layer capacitor

Aluminum Electrolytic Capacitor

manufacturer A EDLC

manufacturer B EDLC

manufacturer C EDLC

®

Figure 2. Actual Capacitance vs. Pulse Width

BestCap® Ultra-low ESR

High Power Pulse Supercapacitors

Introduction to BestCap®

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