Ionistor

Due to the fact that the thickness of the double electric layer (that is, the distance between the “plates” of the capacitor) is extremely small due to the use of electrolytes, and the area of ​​the porous materials of the plates is enormous, the energy stored by the ionizer is higher compared to conventional capacitors of the same size. In addition, the use of a double electric layer instead of a conventional dielectric can significantly increase the surface area of ​​the electrode. A typical capacitance of an ionistor is a few farads at a nominal voltage of 2-10 volts.

The first double-layer capacitor on porous carbon electrodes was patented in 1957 by General Electric ^[1] . Since the exact mechanism at that time was not clear, it was assumed that energy is stored in the pores on the electrodes, which leads to the formation of "extremely high charge storage ability . " A little later, in 1966, Standard Oil of Ohio , Cleveland (SOHIO), USA patented an element that stored energy in a double layer ^[2] .

Faced with the fact of a small volume of sales, in 1971 SOHIO transferred the license to NEC , which was able to successfully promote the product on the market under the name “Supercapacitor”. In 1978, Panasonic launched the Gold Capacitor (Gold Cap), operating on the same principle. These capacitors had a relatively high internal resistance , limiting the energy output, and were used in power supply circuits of volatile memory ( SRAM ).

Ionists in the USSR were announced in Radio magazine No. 5 in 1978. These were KI1-1 ionistors and they had a capacitance of 0.1 to 50 F, depending on the size.

The first low internal resistance ionistors for use in high-power circuits were developed by PRI in 1982. On the market, these ionistors appeared under the name “PRI Ultracapacitor”.

1. Ionistors with perfectly polarizable carbon electrodes (“perfect” ionistor, ionic capacitor). They do not use electrochemical reactions; they work due to ion transfer between the electrodes. Some electrolyte options: 30% KOH aqueous solution; 38% aqueous solution of H ₂ SO ₄ ; organic electrolytes ^[3] .
2. Ionistors with an ideally polarizable carbon electrode and non-polarizable or weakly polarizable cathode or anode (“hybrid” ionistors).
   An electrochemical reaction occurs at one electrode. Options: Ag (-) and solid electrolyte ; 30% aqueous solution of KOH and (+) ^[3] .
3. Pseudo- capacitors are ionistors that use reversible electrochemical processes on the surface of electrodes . They have a high specific capacity. Electrochemical scheme: (-) Ni (H) / 30% aqueous solution of KOH / NiOOH (+); (-) C (H) / 38% aqueous solution of H ₂ SO ₄ / PbSO ₄ ( PbO ₂ ) (+) ^[3] .

With the advent of ionistors, it became possible to use capacitors in electrical circuits not only as a converting element, but also as a voltage source. Widely used as a replacement battery for storing information about the parameters of the product in the absence of external power. Such elements have both several advantages and a number of disadvantages over conventional chemical current sources - galvanic cells and batteries :

Weaknesses

• The high price of ionistors with large discharge currents, preventing their widespread use.
• Voltage directly depends on the degree of charge.
• Possibility of burnout of internal contacts during short circuit for high-capacity ionistors with low internal resistance.
• Low operating voltage compared to most other types of capacitors.
• Significantly greater self-discharge compared to batteries: about 1 μA for an ionistor 2 × × 2.5 V ^[4] .
• Significantly lower charge transfer rate compared to conventional capacitors.

Benefits

• Large maximum currents for charging and discharging.
• Small degradation even after hundreds of thousands of charge / discharge cycles. Studies were conducted to determine the maximum number of charge-discharge cycles. After 100,000 cycles, no degradation was observed.
• The high internal resistance of most ionistors (prevents fast self-discharge, as well as overheating and destruction).
• The ionistor has a long service life (at 0.6 U _nom. About 40,000 hours with a slight decrease in capacity).
• Light weight compared to electrolytic capacitors of a similar capacity.
• Low toxicity of materials (except organic electrolytes).
• Non-polarity (although “+” and “-” are indicated on the ionistors, this is done to indicate the polarity of the residual voltage after charging it at the factory).
• Low dependence on ambient temperature: they can work both in frost and in heat.
• Greater mechanical strength: tolerate multiple overloads.

Electrodes are performed, as a rule, by the use of porous materials, such as activated carbon or foamed metals; and these metals are selected according to the type of electrolyte. The total surface area of ​​such a porous material is many times larger than that of a similar, but with a smooth surface, which made it possible to store the charge in an appropriate volume.

The energy density of ionistors is still several times less than the capacity of batteries. For example, the energy density of the BCAP3000 (3000 F, 2.7 V) with a mass of 0.51 kg is 21.4 kJ / kg (6 Wh / kg). This is 7.6 times less than the energy density of lead electrolytic batteries, 25 times less than lithium-polymer batteries , but ten times more than the energy density of an electrolytic capacitor .

The power density of the ionistor depends on the internal resistance. In the latest models of ionistors, the internal resistance is quite small, which allows you to get power comparable to battery power.

In 2008, Indian researchers developed a prototype graphene- based ionistor with a specific energy consumption of up to 32 W · h / kg, comparable with that for lead-acid batteries (30–40 W · h / kg) ^[5] .

In 2011, Korean scientists, led by Professor Choi Jung-wook, developed a supercapacitor made using graphene and nitrogen, providing double capacity compared to conventional energy sources of the same class. Improving the electrical properties of the battery was achieved by the addition of nitrogen ^[6] .

Vehicles

Heavy and public transport

Currently, buses powered by ionistors are manufactured by Hyundai Motor , Trolza , and Belkommunmash ^[7] .

Hyundai Motor ionistor buses are ordinary electric buses powered by onboard ionistors. As conceived by the designers of Hyundai Motor, such a bus will be charged at every second or every third stop, and the duration of the stop is enough to recharge the bus ionistors. Hyundai Motor positions its bus on ionistors as an economical replacement for a trolley bus (there is no need to lay a contact network) or a diesel (and even hydrogen) bus (electricity is still cheaper than diesel or hydrogen fuel).

Ionistor buses from Trolza are technically “rodless trolley buses”. That is, structurally, it is a trolley bus, but without power rods from the contact network and, accordingly, with electric drive power from ionistors.

But ionistors are especially promising as a means of implementing an autonomous running system for conventional trolley buses. A trolleybus equipped with ionizers is approaching the bus in terms of maneuverability. In particular, such a trolleybus may:

• to pass separate short sections of the route that are not equipped with a contact network (including, if necessary, move around when it is impossible to move along the regular route of the route at some section of the route);
• go through the breakage points of the contact network line;
• the ability to go around obstacles even when the length of the collector rods does not allow it (the driver of the trolleybus equipped with ionizers in this case will simply lower the collector rods and go around the obstacle, after which he will again raise the collector rods and continue to move in the normal mode);
• there is no need to develop a contact network in the depot and on the reversal rings at the final stops - in the depot and on the reversal rings the trolleybuses equipped with ionizers maneuver with the current collector rods lowered.

Thus, the trolleybus system, using trolleybuses equipped with ionistors, approaches the flexibility of a conventional bus system.

Since May 2017, the first Belarusian electric buses Belkommunmash E433 Vitovt Max Electro have been used in Minsk ^[8] . Electric buses are charged at three charging stations located at the end points of the routes. Charging with a current of 500 amperes lasts 5-8 minutes. An empty electric bus travels 20 km on a single charge. Ionistors are produced by Chengdu Xinju Silk Road Development LLC in the Great Stone Sino-Belarusian Industrial Park.

Car

E-mobile - a car project being developed in the Russian Federation, used a supercapacitor as the main means for accumulating electric energy. These supercapacitors themselves were not mass-produced and were developed in parallel with the car.

Auto Racing

The KERS system used in Formula 1 uses precisely ionistors.

Consumer Electronics

They are used for main and backup power in flash units , flashlights , pocket players and automatic utility meters - wherever you need to quickly charge the device. A laser detector of breast cancer using ionistors charges in 2.5 minutes and works for 1 minute ^[9] .

Car accessories stores sell ionistors with a capacity of the order of 1F, designed to power car radios (and equipment powered by the cigarette lighter plug) with the ignition turned off and during engine start (on many cars all other consumers are turned off while the starter is running), as well as to smooth out power surges at peak loads, for example, for powerful speakers.

According to MIT employees in 2006 ^[10] , the ionistors may soon replace conventional batteries . In addition, in 2009, an ionistor-based battery was tested in which iron nanoparticles were introduced into the porous material. The resulting double electric layer transmitted electrons twice as fast due to the creation of a tunneling effect . A team of scientists from the University of Texas at Austin has developed a new material, which is a porous bulk carbon. The carbon thus obtained possessed the properties of a supercapacitor. Processing the above material with potassium hydroxide led to the creation of a large number of tiny pores in carbon, which, in combination with an electrolyte, could store a colossal electric charge ^[11] .

Currently, one of the necessary parts of the capacitor has been created - a solid nanocomposite electrolyte with lithium ion conductivity. The development of electrodes for a capacitor is ongoing. One of the tasks is to reduce the size of the ionistor due to the internal structure ^[12] .

Scientists from the Center for Nanotechnology of the University of Central Florida (UCF) in 2016 developed a flexible ionistor consisting of millions of nanometer wires coated with a sheath of two-dimensional dichalcogenides. Such a supercapacitor can withstand more than 30 thousand charge cycles ^[13] .

In 2019, Russian scientists from the Skolkovo Institute of Science and Technology (Skoltech) ( Skolkovo ) developed a new method for replacing carbon atoms with nitrogen atoms in the crystal lattice of supercapacitors, which allows them to increase their capacity sixfold, as well as increase stability in charge-discharge cycles. The invented method for plasma treatment of carbon nano-walls of the structural lattice of ionistors replaces up to 3% of carbon atoms with nitrogen atoms. The specific capacity of the nano-wall after such treatment reaches 600 F / g ^[14] . Scientists also explained, modeled, and described the mechanism by which nitrogen atoms are incorporated into the carbon lattice. This study opens the way to the creation of flexible thin-film supercapacitors based on carbon nano-walls ^[15] .

• Capacitor
• Tunnel effect
• Chemotronic
• Electrochemical supercapacitors
• Honda FCX Clarity

• Parameters of domestic ionistors
• Supercapacitors for electric vehicles - Dmitry Spitsyn

In the article “Let's ride on a capacitor” (first published in the journal “Young Technician” for December 1990 ), a recipe for making an ionistor (there it was called “IONIKS”) is given for a model boat with a motor.

• DIY supercapacitor
• V. Shurygina. Supercapacitors. Assistants or potential competitors to battery packs (rus.) . Magazine "ELECTRONICS: Science, Technology, Business", Issue No. 3/2003. Date of treatment July 20, 2010.
• Overview of Common Errors in Supercapacitor Capacitance Measurements