Researchers at Lomonosov Moscow State University have developed a lithium ion battery cathode material with a very high charge rate getting down to 90 seconds while retaining more than 75% of the initial capacity. The team also believes the discovery may stimulate the development of batteries where expensive lithium could be replaced with cheaper potassium.

Polyhedral representation of the crystal structure of fluoride-phosphate of vanadium and potassium. The yellow denotes a three-dimensional channel system, which provides rapid transport of Li+ ions. Image Credit: Stanislav Fedotov.

Polyhedral representation of the crystal structure of fluoride-phosphate of vanadium and potassium. The yellow denotes a three-dimensional channel system, which provides rapid transport of Li+ ions. Image Credit: Stanislav Fedotov.

Lithium battery chemistry became popular in the 1990s taking the market from the widespread nickel-metal hydride batteries of the time. But, lithium-ion batteries suffer a number of disadvantages.

Noteworthy is their capacity may drop when temperature falls below zero (C). Their price is also disconcerting because they use expensive lithium metal and the cost of processing it to lithium-ion material. For instance, lithium-ion batteries make up about half the price of a Tesla Model S. On the other hand, lithium-ion batteries are compact, easy to use and highly capacity meaning device charges last long while using a relatively small battery.

A key element of lithium-ion battery capacity is the material used for its cathode. For the majority of the material now in use the capacity limit has already been reached. This drives scientists and engineers to actively search for new cathode materials capable of recharging completely within minutes, operate under high current densities, and store more energy.

One of the potential classes of cathode materials for a new generation of lithium-ion batteries are fluoride-phosphates of transition metals.

Prof. Evgeny Antipov, correspondent member of the Russian Academy of Sciences and the head of the MSU Electrochemistry Department, oversaw the research carried out by a team of MSU research scientists together with their Russian and Belgian colleagues. The program was pointed to creation of a new high-power cathode material based on a fluoride-phosphate of vanadium and potassium for lithium-ion batteries.

The team’s research results have been published in Chemistry of Materials.

Stanislav Fedotov, one of the authors who is a junior research scientist at Electrochemistry Department, Faculty of Chemistry, MSU said, “The work is based on a simple idea of geometric and crystal-chemical conformity of ionic sublattices.”

The scientists successfully stabilized a unique crystal structure, which provides a fast transport of lithium ions through spatial cavities and channels. This resulted in the novel cathode material demonstrating a high charge/discharge rate (down to 90 seconds) retaining more than 75% of an initial specific capacity. With its morphology and composition optimized, this material may become a serious contender to such well-known and commercialized high-power cathode materials as NaSICON.

According to the authors, the results of the research may not only open up ample opportunities in searching and further synthesis of new cathode materials for lithium-ion batteries, but also promote the development of a new battery type where the role of a mobile ion (a charge carrier) would be performed by potassium ions instead of lithium ions.

Fedotov explained, “It is assumed that such batteries would not only deliver high energy density, but would also be economically attractive due to a replacement of expensive lithium-containing components with cheaper and hence affordable potassium-containing analogues.”

This looks better than one might first think. Lomonosov professors have won 11 Nobel prizes over the past century and it is a huge university with a large international student population. Peer reviewed in a good journal, lets hope industry has a look and check to see if the material preparation would scale up.


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