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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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Material selection
and construction
carbon
electrodes
Electrolyte
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Separator soaked in electrolyte
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■ Electrodes
■ Separator
■ Electrolyte
■ Wound component
■ Case
Figure 2. Operation of an Ultracapacitor. A si mple ultracapacitor ut ilizes two similar electrod es (typica lly
ca rbon) with a separator and electrolyte to create the electrochemica l double layer that governs operation . 7
BATTERIES AND ULTRACAPS
For an ultracapacitor, energy is stored within the electrica l double layer, which is a
physica l storage mechanism . Contrast this with batteries, where charge and discharge
take place through a chemical (Farada ic) reaction . Since charge is stored physically,
there is no direct degradation mechanism that limits cycle life. Side reactions do occur,
which prevents infinite cycle life, but ultracaps can often be cycled tens of millions of
times .8 Batteries store their energy through chemica l reaction; consequently, cycle life
is much shorter and heavily dependent on the depth of discharge . In contrast, there are
no limitations to the discharge depth with an ultracapacitor. Table 1 addresses some of
the general characteristics of batteries and ultracapacitors, which can help to determine
the preferred system for a specified application . The values are based upon 2008 data,
so some numbers are outdated, but the relative va lues remain consistent. There are
now hybrid devices that blur the boundaries further by introducing a battery-like
electrode to replace one of the two identical electrodes in a traditional ultracapacitor.
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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.