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AAWSAP DIRD, Ultracapacitors as Energy and Power Storage Devices, November 2010

U.S. Department of War · 2010-11-01 · 34 pages · text from the file's own layer

This Defense Intelligence Reference Document was prepared by the Defense Intelligence Agency's Defense Warning Office and dated 1 November 2010. It is one of a series of advanced technology reports produced under the Advanced Aerospace Weapons System Applications Program. The report reviews how ultracapacitors work, how they compare with batteries, their history and materials, and their commercial, military and aerospace uses. It concludes that new materials and cell designs will raise energy density and that the U.S. government must understand the devices' spectral signatures.

From the source: Release of 2026-09-18 Incident: 11/1/10, Las Vegas, Nevada. Released with redactions. This document is a Defense Intelligence Reference Document (DIRD), a technical reference format used by the Defense Intelligence Agency (DIA) to capture baseline knowledge on a specific topic for later analytic use. DIRDs are best understood as reference and synthesis products rather than as original research. It is one of 38 DIRDs produced under the Advanced Aerospace Weapon System Applications Program (AAWSAP) between 2009 and 2011. Because AAWSAP’s scope permitted a broad range of supporting topics, not every DIRD in the series directly concerns aerospace systems or future threat assessment. The following summary reflects the DIRD’s scope and framing at the time of writing and should not be read as implying current validation of the concepts discussed. This DIRD surveys ultracapacitors as high-power energy-storage devices and argues that their main value lies in extremely rapid charge and discharge, very long cycle life, and usefulness in systems that need short bursts of power rather than sustained energy delivery. The report explains how ultracapacitors differ from batteries, reviews the materials and cell designs that determine their performance, and emphasizes that they are especially useful for power stabilization, backup power, load leveling, regenerative braking, and other applications where fast energy transfer matters more than total stored energy. It also notes their drawbacks, including lower energy density, self-discharge, and voltage-management requirements that limit their usefulness as stand-alone replacements for batteries in many applications. The document presents ultracapacitors as a maturing and increasingly important technology whose most credible aerospace and military uses lie in pulsed-power, missile and munitions systems, electric propulsion support, and other hybrid power architectures rather than in long-duration primary energy storage.

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Chapter 1: Concept
Overview
Ultracapacitors, also known as
supercapacitors, hybrid capacitors,
electrochemical capacitors, electrochemical
double-layer capacitors, or ultracaps, are
energy-storage platforms that offer energy
storage capable of extremely rapid charge
and discharge rates. Ultracapacitors also
have the ability to be cycled hundreds of
thousands of times. The phenomenal
charge and discharge capabilities make
them ideal for supporting volatile memory
and computing applications, energy
efficiency/capture processes, and high
power applications. Ultracaps store their
charge in the electrical double layer
between the electrode and the electrolyte.
Charge storage is a physical mechanism
rather than a chemical phase change, so
these are theoretically capable of cycling an
infinite number of times. 2 One of the Figure 1. Ultracaps in Various Configurations.'
disadvantages of ultracaps can be a high
self-discharge rate. 3 The charge and discharge voltage output for an ultracap is a
slop ing linear curve, which allows for straightforward and accurate state-of-charge
monitoring.4 The real advantage of an ultracapacitor is the ability to deliver or accept
bursts of power in a short time.
Ultracaps were introduced in 1966 and found initial use 12 years later as backup power
devices for volatile memory and clocks. Over the last 30 years, numerous advances
have been made that have led to many uses of ultracaps, from transportation to
portable electronics and more. Ultracaps are becom ing more affordable as activated
carbon electrodes and manufacturing improvements have driven costs down. Several
companies now make ultracapacitors to fill a broad spectrum of applications. Figure 1
shows a number of ultracaps with various capacities to fill a range of functions.
Transportation, microelectronics, and aerospace markets are some of the many areas
where ultracaps have become enablers. Advanced materials and improved cell designs
will lead to improvements in both power density and energy density. The improved
performance is expected to make ultracaps important components for efficient power
leveling and high-power receiving and delivery. The unique signature of ultracapacitors
must be understood for aerospace and military applications.
As an electrochemical capacitor, ultracapacitors store energy within the electric double
layer formed at the interface between the electrode and electrolyte. In a conventional
capacitor, the energy is stored by moving charge carriers from one plate to another,
and the charge separation creates a potential. Voltage differentials in a conventional
capacitor are dependent upon the dielectric material separating the plates. In the
ultracap, the electrical double layer is the separation of charge in a vanish ingly thin gap
between two plates. Figure 2 depicts the components and basic design of the ultracap,
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Official release, from the pursue collection. The PDF is mirrored here; the original link is above. 34 pages are in the text index: search them above, or from the library's search.