A team of scientists at Tokyo University of Science are focusing on the replacement of the exhaustible element lithium with better alternatives like sodium and potassium. Sodium and potassium are in the same alkali metal group in the periodic table of elements, and their chemical natures are, therefore, quite similar. But, unlike lithium, these elements are widely abundant on Earth.
The research group led, by Prof Shinichi Komaba, analyzed the workings of KIBs (K-ion batteries) in a comprehensive review published in Chemical Reviews. Their paper encompasses development of KIB cathode and anode materials, various electrolytes and all-solid KIBs, as well as electrode doping and electrolyte additives. The review compares the different materials used in lithium-, sodium-, and potassium-ion batteries.
Researchers say the continuous development of KIBs will hopefully bring about a rise in the use of this alternative to lithium batteries. Besides being free from scarce/toxic elements, the low standard electrode potentials of K/K+ electrodes lead to high operation voltages competitive to those observed in lithium cells. Moreover, K+ ions exhibit faster ionic diffusion in electrolytes due to weaker interaction with solvents and anions than that of Li+ ions; this is makes it possible to realize high-power KIBs.
“As evidenced by recent intensive research, KIBs are recognized as promising next-generation battery candidates owing to their unique characteristics, such as cost-effectiveness, high voltage, and high-power operation. Further improvements to the performance of KIBs would pave the way for their practical application,” explains Prof Komaba.
However, research on certain aspects of KIBs, such as their safety, has been limited. Komaba thinks the focus should be on obtaining more insight into what’s going on physically and chemically between the different components and elements. “Research on KIBs, including electrode materials, non-aqueous/solid electrolytes, and additives will provide new insights into the electrode reactions and solid ionics, opening up new strategies that would allow for the creation of next-generation batteries,” says Komaba. His research group has also focused on supercapacitors and biofuel cells along with sodium-ion batteries, which could all find important niches in a more sustainable society.