Aluminum ion accumulator

An aluminum ion accumulator , also known as aluminum ion accumulator , is a type of accumulator based on aluminum compounds. Its structure is similar to the lithium ion battery , but the light metal aluminum is used instead of lithium on the negative electrode . Aluminum-ion accumulators, in different variations, have been the target of various research projects since the 1980s. For example, improvements such as comparatively short charging times were reported at Stanford University in 2015 ; practical structures for these accumulators are limited to individual prototypes. The battery did not ignite during tests, even if it was badly damaged in use.

The replacement of lithium by aluminum on the negative electrode results in a lower electrical cell voltage of 2.65  V than in comparison to lithium ion batteries with approx. 3.7 V. However, the theoretically possible energy density of up to 1 kWh / kg is clear higher than compared to lithium ion batteries with a limit of around 400 Wh / kg. The difference arises from the fact that aluminum has three valence electrons while lithium has only one valence electron.

The practical difficulties with aluminum-ion accumulators include the short shelf life and the fact that the specific capacity depends on the operating temperature and the number of charging cycles.

Reaction equations

The following chemical reaction takes place on the negative electrode. The reaction runs from left to right when the battery is being charged; when discharging, the reversible chemical process runs in the opposite direction:

${\displaystyle \mathrm {Al} +\mathrm {7AlCl_{4}^{-}} \leftrightarrows \mathrm {4Al_{2}Cl_{7}^{-}} +\mathrm {3e^{-}} }$

The following applies to the positive electrode:

${\displaystyle \mathrm {2MnO_{2}} +\mathrm {Li^{+}} +\mathrm {e^{-}} \leftrightarrows \mathrm {LiMn_{2}O_{4}} }$

Together, the reaction equation for the entire battery is given as:

${\displaystyle \mathrm {Al} +\mathrm {7AlCl_{4}^{-}} +\mathrm {6MnO_{2}} +\mathrm {3Li^{+}} \leftrightarrows \mathrm {4Al_{2}Cl_{7}^{-}} +\mathrm {3LiMn_{2}O_{4}} }$

In this case, manganese (IV) oxide is used as the cathode material, but there are also approaches that use vanadium (V) oxide or graphite . To maximize the surface area, the electrodes are designed in the form of nanowires in the various experimental setups and different electrolytes are used.

Web links

• ALION project - European research project on Al-ion batteries (Engl.)

Individual evidence

1. ↑ ^{a b} Meng-Chang Lin et al .: An ultrafast rechargeable aluminum-ion battery . In: Nature . tape 520 , no. 7547 . Macmillan Publishers Limited, S. 324–328 , doi : 10.1038 / nature14340 .
2. ↑ Aluminum batteries: The dream of all smartphone users. On: Wissenschaft.de from July 10, 2015.
3. ^ Oak Ridge National Laboratory: Aluminum-Ion Battery to Transform 21st Century Energy Storage . Oak Ridge National Laboratory . Archived from the original on November 19, 2015. Retrieved October 30, 2014.
4. ↑ John Hewitt: DoE calls for a chemical battery with 5x capacity, within 5 years - can it be done? . Extreme tech. Retrieved October 30, 2014.
5. ↑ Leland Teschler: Goodbye to lithium-ion batteries? In: MachineDesign.com. March 22, 2012, accessed June 16, 2016 . 
6. ↑ N. Jayaprakash, SK Das, LA Archer: The rechargeable aluminum-ion battery . In: Chemical Communications . tape 47 , no. 47 , 2011, p. 12610 , doi : 10.1039 / C1CC15779E .