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. Credit: Stanislav Fedotov
A cathode material for li-ion batteries with a very high charge rate – down to 90s – has been created, retaining more than 75% of an initial capacity. The discovery may stipulate the development of batteries where expensive lithium could be replaced with cheaper potassium.
Nowadays Li-ion batteries power a wide range of electronic devices: mobile phones, tablets, laptops. They became popular in 90s and subsequently ousted widespread nickel-metal hydride batteries. However, their capacity may drop when temperature falls below 0. The price is also discomforting, which is mostly caused by use of expensive lithium-containing materials. For instance, Li-ion batteries make about half a price of a popular electro car Tesla Model S. On the other hand, Li-ion batteries are compact, easy to use and highly capacious, ie the device would live long having a relatively small battery.
A key element of the Li-ion batteries limiting its capacity is a material used for its cathode. For the majority of the materials their capacity limit has already been reached. Hence, scientists and engineers are actively searching for new cathode materials capable of recharging completely within minutes, operate under high current densities, and store more energy.
One of the most prospective classes of cathode materials for a new generation of Li-ion batteries are fluoride-phosphates of transition metals. Prof. Evgeny Antipov et al made a new high-power cathode material based on a fluoride-phosphate of vanadium and potassium for Li-ion batteries.
‘The work is based on a simple idea of geometric and crystal-chemical conformity of ionic sublattices,’ – says Fedotov. They stabilized a unique crystal structure, which provides a fast transport of lithium ions through spatial cavities and channels. Thus the cathode material demonstrated high charge/ discharge rates (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.
This may not only open up ample opportunities in searching and further synthesis of new cathode materials for Li-ion batteries, but also promote the development of a new battery type where a role of a mobile ion (a charge carrier) would be performed by potassium ions instead of lithium. 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. http://www.eurekalert.org/pub_releases/2016-02/lmsu-nmt022016.php
Recent Comments