Documents / Official release
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.
UNCLASSIFIED1/FOR 8ffl@IAL tt91! e"t I Chapter 2: Materials Technology The standard electrochemica l capacitor is made of two electrodes, an electrolyte, and a separator, packaged in either a metal container or a laminated pouch. Ultracapacitors are often packaged in a fash ion similar to a typical battery configuration. The separator is an ultrathin material that allows ion transport but is electrically insulating. There are several polymer separators on the market that have the desired porosity needed to create fast ion transport. The electrodes are traditionally the same material in an ultracapacitor-this is in stark contrast to a battery. Electrodes are typically carbon; this is advantageous in making a cost-effective energy/power-storage device . Activated carbon has a very high surface area, vital to storing energy in the electrica l double layer between the electrode and the electrolyte. This th in double layer is responsible for the impressive high-power-storage capabilities of the ultracapacitor. The electrolyte's resistivity and dielectric constant play a vital role in behavior of the double layer; consequently, the choice of electrolyte impacts performance. The earliest electrochemical capacitors were introduced 30+ years ago; they were symmetric designs (two identical electrodes) in aqueous electrolyte. Wh ile these electrolytes have excellent ionic conductivity, the operating cell voltage was limited to ~1.2 V/cell and these had a nominal cell rating of ~0 .9 volts . In the second generation of electrochemical capacitors, the use of organic electrolyte led to an increase of the rated cell voltage from about 0.9 V/cell to 2.3-2.7 V/cell. Today, ultracapacitors using an organic electrolyte are the most popular. 14 ELECTROLYTES Initial ultracaps used aqueous electrolytes, saturated with Al2(SO4)3, or 30% concentrations of H2SO4 or KOH. While these electrolytes have excellent ionic conductivity, the operating voltage is limited to 1.2 volts using carbon electrodes. Improvements to ultracapacitor performance were made by transitioning from aqueous electrolytes to an organic medium. Organic electrolytes have lower ionic conductivity, but the higher breakdown potential increases the nominal cell voltage. An increase in cell voltage up to as high as 3 volts has been realized by use of an organ ic electrolyte. These electrolytes are typically an ammonium salt dissolved in an organic solvent, such as propylene carbonate or aceton itrile. Table 3 highlights the comparison between the various electrolytes used in ultracapacitors. Ionic liquids are beginn ing to become more common in ultracapacitors , as they allow for an increase in cell voltage to as high as 4 vol t s. These ionic li quids have a higher resist ivity, especially at lower t emperatures . The tradeoff in resistivit y for voltage may be beneficial for some high -power applicati ons. Table 3: Properties of Various Electrolytes Used in Ultracapacitors1 5 Electrolyte KOH Sulfuric acid Propyl en e carbonate Acetonitrile I onic liquid Density (am/cm3) 1.29 1.2 1.2 0.78 1. 3- 1.5 Resistivity (Ohm-cm) 1.9 1.35 52 18 125 (25°C) 28 ( 100°C) Cell Voltaae 1.0 1.0 2.5- 3.0 2.5-3 .0 4. 0 3 .2 5 UNCLASSIFIEO/fFOA OFFI&I:.l.b YS& ONLY 8
Not linked to a story yet.
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.