Slight chemical changes in the structure of rechargeable batteries can extend the useful life of mobile communication and computing devices
Mobile phones, laptops, iPods - the prosperity in mobile communication and computing devices depends to a large extent on rechargeable lithium-ion batteries for energy transfer. These batteries offer the highest energy capacity, enable the operation of portable computers for a reasonable time and do not exhibit memory defects compared to other rechargeable batteries. However, rechargeable batteries available in the market are still not fully satisfactory.
Modern and efficient rechargeable batteries and fuel cells require materials with an increased ability to transfer lithium ions. Researchers from Germany have now developed a new type of inorganic ionic conductors with a structure similar to the natural mineral argyrodite (Ag8GeS6). A group of researchers from Germany, led by Hans-Jörg Diesroth, report in the Journal Angewandte Chemie on the characterization of a synthesized material, which is equivalent to the ore argyrodite, which has the highest electrical conductivity known and is composed of lithium, phosphorus, sulfur and bromine atoms.
In ionic conductors, the charge is not transferred in the form of electrons, a situation that exists in metals; On the other hand, the charge is transferred in the form of charged particles - mostly, lithium ions. This transfer requires materials in which the lithium ions can move as freely as possible. The research group from the University of Siegen, in collaboration with scientists from the University of Münster, began their research on this mineral known for a long time - argyrodite, a natural mineral consisting of silver, germanium and sulfur atoms which was discovered in Germany in 1885 and contains mobile silver ions within it.
The separate components in argyrodite can be replaced by several other atoms without changing the characteristic structure of this mineral. The term "argyrodite" today refers to a whole family of materials with a very specific atomic arrangement and type of spatial structure.
The group led by Daisroth produced a version of this ore in which the silver atoms were replaced by lithium atoms, the germanium atoms by phosphorus atoms and some of the sulfur atoms by halides (chloride, bromide or iodide), obtaining argyrodite-like structures with the composition Li6PS5X (X: Cl-, Br-, I-).
In the crystal lattice, the phosphorus, sulfur and halide atoms adopt a compressed spatial fabric of the tetrahedral type in which the smears contain, in a mostly regular manner, lithium ions. The lithium ions can "jump" from one smear to another. The existence of the mobile ions indicates that the crystal has a high ionic conductivity and the structures containing bromine atoms have the highest conductivity of lithium ions known to the science of argyrodite-like materials. The scientists examined the lithium-bearing argyrodites in depth using single-crystal X-ray diffraction crystallography and nuclear magnetic resonance (NMR) spectroscopy. Tests of this type allow accurate characterization of the crystal structures of these materials and provide fascinating insights into the dynamics of mobile lithium ions.
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Basically, a battery consists of 3 main parts: an anode that usually breaks down into a lithium ion and an electron, a cathode that picks up a lithium ion and an electron and reacts with them, and an electrolyte that serves as a medium to transfer the lithium ions. In fact, a battery is a galvanic cell, where the electrolyte is usually not water with salt (mainly KNO3), but another substitute. Can be a polymer or any material with high ionic conductivity.
The material described in the article has a high ionic conductivity, therefore it is suitable to be a replacement for the electrolyte. In general, the better the electrolyte, the more current can be drawn from the battery and the lower the internal resistance of the battery.
So what is the conclusion - that this material should be added to the batteries or what... why isn't it written?
Another note
The article states: (lithium ion batteries) "do not exhibit memory deficiencies compared to other rechargeable batteries."
Should be: do not exhibit memory like other rechargeable batteries.
Explanation: A memory phenomenon in rechargeable batteries is a negative phenomenon according to which if a battery is charged before it has run out, it remembers the short operating time it was required to operate before charging and subsequently reduces its capacity.
By way of the parable: the battery says - I can operate for a week before I run out, but every time I am charged after three days; So if they charge me every three days anyway, then I will really run out after three days.