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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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ELECTRODES
Carbon has been the optimal electrode material for ultracapacitors since their
commercial introduction over 30 years ago. Pseudocapacitor systems use a combination
of a carbon electrode and a battery-like electrode, such as a conductive polymer or a
metal oxide. The hig h surface area of carbon makes it an extremely attractive option
for ultracap electrodes. Carbon chemistry is quite we ll known, and hig h surface area
and low cost ensures carbo n's cont inued use for the near future. While carbon has been
used in electrochemica l systems for many years, there are many nua nces that make its
properties and performance vary significantly amongst the many types of carbon. The
use of a carbon electrode makes ultracaps affordable for use in many systems.
Activated carbon is readily available, can be made from many source materia ls, and is
inexpensive . Materials science activities for electrodes are focused on improving the
carbon electrodes and introduci ng alternat ive materia ls to create an asymmetric
electrode.
Types of carbon can include activated carbon, carbon cloth, aerogels, porous carbon,
carbon nanotubes, and graphene. The properties of carbon can change dramatically
based upon processing, having a major im pact to the porosity and active surface area.
Activated carbon has an extremely high surface area, is inexpensive, and is produced at
a global scale for use in a number of applications. For these reasons, activated carbon
is the traditional carbon of choice for ultracapacitor applications. Recent advances in
carbon materials development have led to a number of options for ultracapacitor
electrodes. Table 4 demonstrates a number of electrode materials in use today and t he
corresponding performance of these ultracaps.
Table 4: Properties of Various Materials Used in Electrochemical Capacitor
Electrode Materials16
Material
Density
(g/cm 3 ) Electrolyte F/g F/cm 3
Activated Carbon 0.7 KOH 160 112
Oroanic 100 70
Carbon Cloth 0.35 KOH 200 70
Organic 100 35
Aerogel Carbon 0.6 KOH
Orqanic
75
125 84
Porous Carbon from SiC 0.7 KOH 175 122
Oroanic 100 70
Porous Carbon from TiC 0.5 KOH 220 110
Organic 120 60
Anhydrous RuO2 2.7 Sulfuric Acid 150 405
Hvdrous RuO2 2.0 Sulfuric Acid 650 1 300
Doped Conductive Polvmer 0.7 Orqanic 450 315
UNCLASSIFIEO/fFOA OFFI&I:.l.b YS& ONLY
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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.