Draft:Original research/Electrochemical capacitors

File:Portable super capacitor battery bank.jpg

The image shows a portable super capacitor battery bank. Credit: Mashpedia.

"Electrochemical capacitors, also called supercapacitors, store energy using either ion adsorption (electrochemical double layer capacitors) or fast surface redox reactions (pseudo-capacitors)."

Usually, a capacitor is a device used to store an electric charge, consisting of one or more pairs of conductors separated by an insulator. Template:Clear

Electrochemistry

Template:Main "The discovery that ion desolvation occurs in pores smaller than the solvated ions has led to higher capacitance for electrochemical double layer capacitors using carbon electrodes with subnanometre pores, and opened the door to designing high-energy density devices using a variety of electrolytes."

Planetary sciences

Template:Main For a capacitor in an electrical or electronic circuit, charge balance occurs within the capacitor. But, for a planetary capacitor with a variable charge between the spherical plates, the charge between the plates should be negative. The bleed out of positive charges allows the full internal surface of a super capacitor to be used for negative charge only.

Theoretical super capacitors

Def. an

1. "electronic component capable of storing electrical energy in an electric field; especially one consisting of two conductors separated by a dielectric" or
2. "electronic component capable of storing an electric charge; especially one consisting of two conductors separated by a dielectric"

is called a capacitor.

Capacitances

This is a simple capacitor circuit with a resistor and ammeter in series. Credit: Sjlegg.

Def. a "property of an electric circuit or its element that permits it to store charge, defined as the ratio of stored charge to potential over that element or circuit (Q/V); SI unit: farad (F)" or a "property of an element of an electrical circuit that permits it to store charge" is called a capacitance.

In the simple, ideal circuit on the right there is a capacitor (two equal parallel plates) with a resistor (rectangular box) and ammeter (A) in series, a voltmeter (V) in parallel, and a switch (at the top) and cell (two different length parallel plates) for charging.

"If you place two conducting plates near each other, with an insulator (known as a dielectric) in between, and you charge one plate positively and the other negatively, there will be a uniform electric field between them."

"The capacitance C of a capacitor is:

$C=\frac{Q}{V}$,

where Q is the charge stored by the capacitor, and V is the potential difference between the plates. C is therefore the amount of charge stored on the capcitor per unit potential difference. Capacitance is measured in farads (F). Just as 1 coulomb is a massive amount of charge, a 1F capacitor stores a lot of charge per volt."

"Any capacitor, unless it is physically altered, has a constant capacitance. If it is left uncharged, Q = 0, and so the potential difference across it is 0. If a DC power source is connected to the capacitor, we create a voltage across the capacitor, causing electrons to move around the circuit. This creates a charge on the capacitor equal to CV. If we then disconnect the power source, the charge remains there since it has nowhere to go. The potential difference across the capacitor causes the charge to 'want' to cross the dielectric, creating a spark. However, until the voltage between the plates reaches a certain level (the breakdown voltage of the capacitor), it cannot do this. So, the charge is stored."

"If charge is stored, it can also be released by reconnecting the circuit. If we were to connect a wire of negligible resistance to both ends of the capacitor, all the charge would flow back to where it came from, and so the charge on the capacitor would again, almost instantaneously, be 0. If, however, we put a resistor (or another component with a resistance) in series with the capacitor, the flow of charge (current) is slowed, and so the charge on the capacitor does not become 0 instantly. Instead, we can use the charge to power a component, such as a camera flash."

"Current is the rate of flow of charge. However, current is given by the formula:

$I=\frac{V}{R}.$"

"But, in a capacitor, the voltage depends on the amount of charge left in the capacitor, and so the current is a function of the charge left on the capacitor. The rate of change of charge depends on the value of the charge itself. And so, we should expect to find an exponential relationship:

$Q=Q_0{e}^{-\frac{t}{RC}}$,

where R is the resistance of the resistor in series with the capacitor, Q is the charge on the capacitor at a time t and Q₀ was the charge on the capacitor at t = 0. Since Q = IΔt:

$I\mathrm{\Delta }t=I_0\mathrm{\Delta }t{e}^{-\frac{t}{RC}}$

$I=I_0{e}^{-\frac{t}{RC}}$,

where I is the current flowing at a time t and I₀ was the initial current flowing at t = 0. Since V = IR:

$V=V_0{e}^{-\frac{t}{RC}}.$"

Aluminum electrolytic capacitors

• Basic construction of a non-solid aluminum electrolytic capacitor
• 
  Opened winding of an e-cap with multiple connected foils
• 
  Closeup cross-section of an aluminium electrolytic capacitor design, showing capacitor anode foil with oxide layer, paper spacer soaked with electrolyte, and cathode foil
• 
  Construction of a typical single-ended aluminium electrolytic capacitor with non-solid electrolyte is shown. Credit: Elcap.Template:Tlx

Electronic devices

This is a cut-away drawing of a ceramic disc capacitor. Credit: Inductiveload.

This shows a 100 pF up to 1000 volts ceramic capacitor. Credit: Jens Both Elcap.

In the cut-away drawing on the right the components are as follows:

	English
1	Leads
2	Dipped blue dyed phenolic coating
3	Soldered connection
4	Silver electrode
5	Ceramic dielectric

Parameters of supercapacitors compared with electrolytic capacitors and lithium-ion batteries

Parameter	Aluminum electrolytic capacitors	Supercapacitors			Lithium-ion batteries
		Double-layer capacitors for memory backup	Super-capacitors for power applications	Pseudo- and hybrid capacitors (Li-Ion capacitors)
Temperature range (°C)	−40 to +125	−40 to +70	−20 to +70	−20 to +70	−20 to +60
Cell voltage (V)	4 to 630	1.2 to 3.3	2.2 to 3.3	2.2 to 3.8	2.5 to 4.2
Charge/discharge cycles	unlimited	105 to 106	105 to 106	2 • 104 to 105	500 to 104
Capacitance range (F)	≤ 2.7	0.1 to 470	100 to 12000	300 to 3300	—
Specific energy (Wh/kg)	0.01 to 0.3	1.5 to 3.9	4 to 9	10 to 15	100 to 265
Specific power (kW/kg)	> 100	2 to 10	3 to 10	3 to 14	0.3 to 1.5
Self discharge time at room temperature	short (days)	middle (weeks)	middle (weeks)	long (month)	long (month)
Efficiency (%)	99	95	95	90	90
Life time at room temperature (years)	> 20	5 to 10	5 to 10	5 to 10	3 to 5

Wound and stacked supercapacitors

• Construction details of wound and stacked supercapacitors with activated carbon electrodes
• 
  Schematic construction of a wound supercapacitor
  1. terminals, 2. safety vent, 3. sealing disc, 4. aluminum can, 5. positive pole, 6. separator, 7. carbon electrode, 8. collector, 9. carbon electrode, 10. negative pole
• 
  Schematic construction of a supercapacitor with stacked electrodes
  1. positive electrode, 2. negative electrode, 3. separator

Variable capacitors

Principle of the centered rotary cap is for a variable capacitor. Credit: Zátonyi Sándor, (ifj.) Fizped.Template:Tlx

Rotary variable capacitor

Principle of the rotary variable capacitor

• Measurement of the capacitance of a rotary capacitor
• 
  C_min = 20 pF
• 
  C = 269 pF
• 
  C_max = 520 pF

Materials

Template:Main "The chloride permeability of Type V cement concrete specimens was in the range of 2,700 to 3,300 coulombs, putting these concretes in the moderate permeability classification, according to ASTM C1202."

"The electrical resistivity of concrete decreases both due to the presence of moisture and chloride ions."

"AASHTO T277 and ASTM C1202 have specified a rapid test method to rank the chloride penetration resistance of various concretes by applying a potential of 60 V DC to a concrete specimen and measuring the charge passed through the specimen during six hours of testing."

Automobile Electric Power Systems

File:Supercapacitor based energy storage system for automobiles.png

Supercapacitor based energy storage system for automobiles is diagrammed. Credit: Koji Yamamoto, Eiji Hiraki, Toshihiko Tanaka, Mutsuo Nakaoka, and Tomokazu Mishima.Template:Tlx

"Energy storage systems assisted by super capacitor have been widely researched and developed to progress power systems for the electronic vehicles."

The "system is able to perform adequate charge and discharge operation between low-voltage high-current super capacitor side and high-voltage low-current side with drive train and main battery."

Conduction "losses and voltage/current surge are drastically reduced by [zero voltage switching] ZVS operation with loss-less snubber capacitor in high voltage side as well as the synchronous rectification in low-voltage high-current super capacitor side."

"For these applications, bi-directional DC-DC converters to transfer the electric energy between low voltage S.C. based energy storage system and the high voltage drive train including three phase inverter-motor system and the main batter, are required as shown in [the diagram on the right]." Template:Clear

Hypotheses

1. Supercapacitors may provide a material which can be used to make a charge storage device for up to 10¹³ coulombs.

See also

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• Capacitor (3 kB) (8 November 2018)
• Capacitors (6 kB) (26 December 2018)
• Capacitances
• Capacitor leakages
• Capacitors (7 kB) (21 September 2017)
• Charge ontology (37 kB) (25 June 2019)
• Charges (25 kB) (13 September 2019)
• Detectors for radiation astronomy (116 kB) (26 January 2019)
• Electrochemical capacitors (16 kB) (31 October 2019)
• Electron beam heating (19 kB) (31 October 2019)
• Electrospheres (14 kB) (26 May 2019)
• Electrostatic suspension (22 kB) (29 May 2019)
• Geophysics (80 kB) (12 August 2019)
• How-to's (3 kB) (2 July 2019)
• Interstellar vehicles (11 kB) (28 May 2019)
• Lofting technology (91 kB) (9 July 2019)
• Magnetic field reversals
• Measurements (3 kB) (25 June 2019)
• Mems capacitors (30 kB) (25 May 2019)
• Mining geology (24 kB) (16 August 2019)
• Natural electric field of the Earth (27 kB) (23 June 2019)
• Particle fountain (11 kB) (26 May 2019)
• Petrophysics (40 kB) (26 May 2019)
• Physics (30 kB) (22 June 2019)
• Plasmas (13 kB) (2 July 2019)
• Proof of technology (13 kB) (30 August 2019)
• Radiation (154 kB) (25 June 2019)
• Radiation astronomy (169 kB) (23 June 2019)
• Radiation physics (39 kB) (27 October 2019)
• Repellor vehicles (42 kB) (5 August 2019)
• Safety (13 kB) (25 June 2019)
• Shielding (10 kB) (19 August 2019)
• Small solar vehicles (5 kB) (26 May 2019)
• Solar mirrors in the stratosphere (8 kB) (2 September 2019)
• Spacecraft
• Spaceflights (23 kB) (23 June 2019)
• Tantalum capacitors (15 kB) (25 February 2018)
• Technology (46 kB) (23 July 2019)

External links

• Build your own air variable capacitor
• High-res images of historical variable capacitors
• Introduction to capacitors
• Introduction to Variable Vacuum Capacitor