Scientists and researchers at the Pacific Northwest National Laboratory (PNNL) have developed a technology that will help to make the zinc-manganese batteries more efficient and reliable.
Batteries based on manganese and zinc are quite promising, but until that time, engineers and scientists could not make them more succinct and long-lived. Although the first prototypes appeared in the 90s of the last century. To the advantages of this type of battery can be attributed to their ecological safety for the environment.
Now a team of scientists from PNNL finally managed to make zinc-manganese batteries more durable, and their specific capacity in the long term can be compared with lead-acid batteries. How do they do it?
As noted by researchers, the new technology was born through in-depth analysis of chemical and electrical processes occurring inside the battery. On the basis of these studies, scientists have found that in order to maintain efficiency in the manganese-zinc battery is only necessary to control the chemical balance of all occurring processes during the charging and discharging.
The mistake of the previous researches in this field was that scientists thought that processes in the manganese-zinc and lithium-ion batteries are identical. But, as it turned out it is not so. Work of manganese-zinc battery more close to the lead-acid battery – that is, the process of creating a directional flow of charged particles – it is not the flow of ions in the direction from one electrode to the other, but a reversible chemical reaction.
As a result of chemical reactions between the manganese oxide as the positive electrode and the water-containing electrolyte in which it is shipped, a new material – zinc hydroxide sulfate, which essentially serves the third (intermediate) electrode in the battery circuit. Because of it, the effectiveness of the battery is decreased.
To prevent this process, scientists have increased the concentration of manganese in the battery. And studies have shown that it worked. The specific capacity of the battery has increased to 285 mAh / g, and the number of possible charge / discharge cycles (the degree of survivability) to 5000.
However, the concentration of manganese is necessary to control all the time, so that the scientists are continuing their research in this area.