Sodium ion accumulator
The sodium-ion accumulator , English sodium-ion battery (abbreviated to SIB ), serves - like all accumulators - to store electrical energy and uses ions of the alkali metal sodium .
term
The term sodium ion accumulator can be defined differently, more comprehensively or narrowly.
Sodium ion accumulator in the broader sense
“Sodium ion accumulator” can be used to summarize all accumulators that use sodium ions to transport charges in the electrolyte.
The technically most important implementations that fall under this broad definition are thermal batteries (high-temperature batteries) that use liquid sodium and a solid electrolyte . The most important examples due to their commercial use are the zebra battery and the sodium-sulfur accumulator .
Sodium ion accumulator in the narrower sense
Analogous to the narrow definition of the term lithium ion accumulator , which excludes lithium batteries with lithium metal electrodes, sodium ion accumulators can be defined in such a way that sodium ions are used there to store charge in the electrodes. This will exclude the above cells with liquid sodium as there are no sodium ions in this sodium metal electrode.
There is very intensive research which is trying to develop sodium ion batteries with organic electrolytes based on the great success of lithium ion accumulators. A great advantage of organic electrolytes is that they allow higher cell voltages than aqueous solutions. Sodium ion batteries of this type operate at ambient temperature.
There are also sodium ion batteries with aqueous electrolytes. These are called saltwater batteries, especially if the aqueous electrolyte is non-toxic. Aqueous solutions are significantly cheaper than organic electrolytes. They are non-flammable and therefore safer than most lithium ion batteries - thermal runaway is not possible. But they only allow small tensions. The energy density of such sodium ion accumulators is therefore small and they are not suitable for mobile use. Such batteries were commercially available on a small scale as stationary batteries, e.g. B. sold as home storage for solar energy.
Advantages and disadvantages of sodium ion accumulators
Sodium is cheaper than lithium and is easily and practically unlimited available worldwide. This could result in a cost advantage in the raw materials used in battery manufacture. For example, an initial estimate showed that the sodium-ion technology could be cheaper than the lithium-ion technology. It has not yet been clarified whether this cost advantage will actually make the entire system cheaper. In terms of sustainability, researchers hope that sodium cells could be an advantageous alternative to those of lithium. Due to the use of abundant and therefore inexpensive materials, they are considered to be a promising accumulator design for energy storage systems where the weight of the accumulator is not important, for example stationary battery storage power plants for wind energy and solar energy .
Thermal batteries with sodium metal
These use a solid electrolyte (of the sodium β-aluminate type ) to transport the sodium ions. Since the conductivity of solid electrolytes is only high enough at sufficiently high temperatures, the cells must be kept at a high temperature. The negative pole side can consist of inexpensive liquid sodium, the positive pole side of sulfur in the sodium-sulfur accumulator and of nickel chloride in the Zebra battery (= sodium-nickel chloride accumulator). In contrast to the inexpensive electrodes, the solid electrolyte is relatively expensive.
Sodium ion batteries with aqueous electrolytes
This accumulator was among other names such as salt water battery , English Salt battery water , markets. A special feature of this type of accumulator is that, unlike most accumulators, especially the group of lithium-ion accumulators, it is deep discharge-proof and can be discharged to a final discharge voltage of 0 V without being damaged.
The energy density of aqueous sodium-ion accumulators is 12 to 24 watt hours per liter, far below that of lead or lithium-ion accumulators, which is not a problem with stationary systems, but these sodium-ion accumulators are unsuitable for mobile applications power. They also have a lower cycle stability .
The capacity that can be drawn depends heavily on the discharge current. Sodium-ion batteries of this type are therefore more suitable for applications that require low to medium currents, but do so over long periods of time.
In 2017, sodium ion accumulators only played a minor role economically, but they were the subject of intensive research in various forms and variations. In 2018, the position of the sodium-ion accumulators had improved somewhat, as the production costs compared to lithium batteries had fallen and further rationalization was to be expected through a simpler construction with higher quantities.
Sodium-ion accumulators with organic electrolytes
In the group of sodium ion accumulators with organic electrolytes, which are currently being intensively researched, there is a great variety of proposed materials for anode , cathode and electrolyte . This results in many conceivable combinations that lead to different accumulator parameters, one of which is the cell voltage. Sodium salts such as sodium perchlorate , dissolved in anhydrous solvents such as propylene carbonate , have been proposed as electrolytes . The anode material is, among other carbon in the form of graphs used - sodium metal is possible in principle as an anode material, the alkali metal is however chemically attacked by the substances in the electrolyte. Various materials containing sodium ions, such as phosphates and diphosphates , for example sodium iron phosphate, are being researched as cathode materials .
Depending on the materials used, this results in cell voltages in the range between 2 V and 3.5 volts.
literature
- Bruno Scrosati , Jürgen Garche, Werner Tillmetz: Advances in Battery Technologies for Electric Vehicles . 1st edition. Woodhead Publishing, 2015, ISBN 978-1-78242-377-5 .
proof
- ↑ a b c Verònica Palomares, Paula Serras, Irune Villaluenga, Karina B. Hueso, Javier Carretero-González, Teófilo Rojo: Na-ion batteries, recent advances and present challenges to become low cost energy storage systems . In: Energy and Environmental Science . tape 5 , February 2012, p. 5884-5901 , doi : 10.1039 / c2ee02781j .
- ^ Dominique Larcher, Jean-Marie Tarascon: Towards greener and more sustainable batteries for electrical energy storage . In: Nature Chemistry . tape 7 , no. 1 . Springer Nature, January 2015, ISSN 1755-4330 , p. 19-29 , doi : 10.1038 / nchem.2085 ( nature.com ).
- ↑ Huilin Pan, Yong-Sheng Hu, Liquan Chen: Room-temperature stationary sodium-ion batteries for large-scale electric energy storage . In: Energy and Environmental Science . tape 6 , June 2013, p. 2338-2360 , doi : 10.1039 / c3ee40847g .
- ↑ The salt water battery. Retrieved December 11, 2017 .
- ↑ a b Photovoltaik.eu: The salt water battery, article from August 31, 2015
- ↑ a b Jang-Yeon Hwang, Seung-Taek Myung, Yang-Kook Sun: Sodium-ion batteries: present and future . In: Chemical Society Reviews . tape 46 , no. June 12 , 2017, p. 3529-3614 , doi : 10.1039 / C6CS00776G .
- ↑ Solar storage alternative: battery made from salt and water. Retrieved January 27, 2019 .
