Editing Power-to-weight ratio (section)

====Electrostatic, electrolytic and electrochemical capacitors====
[[Capacitor]]s store electric charge onto two electrodes separated by an electric field semi-insulating ([[dielectric]]) medium. Electrostatic capacitors feature planar electrodes onto which electric charge accumulates. [[Electrolytic capacitor]]s use a liquid electrolyte as one of the electrodes and the [[Double layer (interfacial)|electric double layer effect]] upon the surface of the dielectric-electrolyte boundary to increase the amount of charge stored per unit volume. [[Electric double-layer capacitor]]s extend both electrodes with a [[Nanopore|nanoporous]] material such as [[activated carbon]] to significantly increase the surface area upon which electric charge can accumulate, reducing the dielectric medium to nanopores and a very thin high [[permittivity]] separator.

While capacitors tend not to be as temperature sensitive as batteries, they are significantly capacity constrained and without the strength of chemical bonds suffer from self-discharge. Power-to-weight ratio of capacitors is usually higher than batteries because charge transport units within the cell are smaller (electrons rather than ions), however energy-to-weight ratio is conversely usually lower.
{| class="wikitable sortable"
|-
! [[Capacitor]] type
! data-sort-type="number"|[[Capacitance]]
! data-sort-type="number"|[[Voltage]]
! data-sort-type="number"|{{Abbr|[[Temperature|Temp.]]|Temperature}}
! data-sort-type="number"|Energy-to-weight ratio
! data-sort-type="number"|Power-to-weight ratio
|-
| rowspan=2 | ACT Premlis [[lithium-ion capacitor]]<ref>{{cite web|url=http://www.act.jp/eng/premlis/premlis.htm|archive-url=https://web.archive.org/web/20070515231246/http://www.act.jp/eng/premlis/premlis.htm|url-status=dead|archive-date=May 15, 2007|title=Typical Characteristics of Premlis|publisher=Advanced Capacitor Technologies|access-date=September 9, 2010}}</ref>
| rowspan=2 | 2000&nbsp;[[Farad|F]]
| rowspan=2 | 4.0&nbsp;V
| rowspan=2 | 25&nbsp;°C
| 54&nbsp;kJ/kg to 2.0&nbsp;V
| 44.4&nbsp;W/kg @ 5&nbsp;A
|-
| 31&nbsp;kJ/kg to 2.0&nbsp;V
| 850&nbsp;W/kg @ 10&nbsp;A
|-
| rowspan=2 | Nesccap [[Electric double-layer capacitor]]<ref>{{cite web|url=http://www.nesscap.com/data_nesscap/spec_sheets/Spec%2009.pdf|title=Nesccap Ultracapacitor Products&nbsp;– EDLC&nbsp;– Prismatic|publisher=Nesscap Co., Ltd.|access-date=September 10, 2010}} {{dead link|date=July 2017 |bot=InternetArchiveBot |fix-attempted=yes }}</ref>
| rowspan=2 | 5000&nbsp;[[Farad|F]]
| rowspan=2 | 2.7&nbsp;V
| rowspan=2 | 25&nbsp;°C
| 19.58&nbsp;kJ/kg to 1.35&nbsp;V
| 5.44&nbsp;W/kg C/1 (1.875&nbsp;A) <!-- mass 930g, rated energy capacity 0.5*5000*2.7^2 = 5.0625 Wh = 18.225 kJ; rated (C/1) current is then 1.875 A -->
|-
| 5.2&nbsp;kJ/kg to 1.35&nbsp;V
| 5,200&nbsp;W/kg<ref>{{cite web|url=http://www.nesscap.com/products_edlc.htm|title=Nesccap Ultracapacitor (EDLC)|publisher=Nesscap Co., Ltd.|access-date=September 10, 2010|url-status=dead|archive-url=https://web.archive.org/web/20100206022503/http://www.nesscap.com/products_edlc.htm|archive-date=February 6, 2010}}</ref> @ 2,547&nbsp;A <!-- mass 930g, current pulse for 1 second -->
|-
| rowspan=2 | [[EEStor]] EESU [[barium titanate]] [[supercapacitor]]<ref name="USPTO-7466536">{{Ref patent
 | country = US
 | number = 7466536
 | status = patent
 | title = Utilization of poly(ethylene terephthalate) plastic and composition-modified barium titanate powders in a matrix that allows polarization and the use of integrated-circuit technologies for the production of lightweight ultrahigh electrical energy storage units (EESU)
 | pubdate = 16 December 2008
 | gdate = 16 December 2008
 | fdate = 13 August 2004
 | pridate = 13 August 2004
 | invent1 = Weir; Richard Dean
 | invent2 = Nelson; Carl Walter
 | assign1 = EEStor, Inc}}</ref>
| rowspan=2 |30.693&nbsp;[[Farad|F]]
| rowspan=2 |3500&nbsp;V
| rowspan=2 |85&nbsp;°C
| 1471.98&nbsp;kJ/kg
| 80.35&nbsp;W/kg C/5
|-
| 1471.98&nbsp;kJ/kg
| 8,035&nbsp;W/kg 20&nbsp;C
|-
|| [[General Atomics]] 3330CMX2205 [[Capacitor|High Voltage Capacitor]]<ref>{{cite web |url=http://www.ga-esi.com/EP/capacitors/series-CMX-high-energy.php |title=SERIES CMX&nbsp;– Self-Healing Energy Storage Capacitors |url-status=dead |access-date=12 August 2012 |archive-url=https://web.archive.org/web/20130329161712/http://www.ga-esi.com/EP/capacitors/series-CMX-high-energy.php |archive-date=29 March 2013 }}</ref>
|| 20.5&nbsp;[[Farad|mF]]
|| 3300&nbsp;V
|| (unknown)
| 2.3&nbsp;kJ/kg
| (unknown){{Clarify|date=March 2020|reason=6,800,00 is not a valid number}}<!-- 6,800,00 W/kg @ 100&nbsp;kA -->
|}