Cathode materials are crucial to the properties of batteries, including safety and service life. Examples include lithium-nickel-manganese-cobalt-oxide (NMC) and lithium-iron-phosphate (LFP) batteries: the former have high energy capacity, which makes them particularly popular with electric vehicle manufacturers, while the latter are inexpensive and resistant to overheating and combustion, which makes them suitable for urban electric buses.
Skoltech’s solution makes it possible to obtain LFP material in the form of spherical microparticles, ensuring their denser packing. The result is a lithium-ion battery with increased energy density: it will store more energy while having the same mass.
LFP is synthesized via high-temperature processing of the precursor material, which can be obtained by spraying an aqueous suspension of reagents in a stream of hot air. After the spraying, small droplets of the suspension dry instantly, leaving spherical powder particles.
The authors of the study found that if the droplets are dried with microwave radiation instead of hot air, all the original substances in each spherical particle will be distributed more evenly. With subsequent heat treatment, one can form a homogeneous carbon conductive coating that envelops the metal particles, as well as achieve high electrochemical capacity and stable operation of the cathode. Equally important is the fact that, thanks to its high speed, the new method for obtaining LFP makes it possible to save a quarter of the electricity used for hot-air spray drying.
“This can be explained by the fact that the heating of the sprayed droplets is carried out from their center to the periphery due to the direct influence of microwaves and not vice versa, as in the case of hot-air drying. Rapid removal of water from the suspension droplets using microwave radiation makes it possible to achieve a uniform distribution of all components throughout the volume of spherical, or nearly spherical, precursor conglomerates. As a result, a more branched conductive carbon network is formed in the cathode material,” Alexander Savin, researcher at the Center for Energy Science and Technology, is quoted as saying by Skoltech. He believes that this will ensure high electrical conductivity of the battery and the stability of its operation for a long time.
