Argonne National Laboratory (ANL) scientists have developed a new cathode coating to make lithium-ion batteries more safer and conductive.
The researchers utilized an oxidative chemical vapor deposition technique to create their coating.
Battery makers have been trying to keep a battery’s cathode electrically and ionically conductive, as well as ensure that the battery stays safe after many cycles.
According to Argonne battery scientist Khalil Amine, the new coating helps solve these and several other potential issues with lithium-ion batteries all in one stroke.
Its like really hitting five or six birds with one stone, explains Amine.
Amine and his teammates took particles of Argonne’s pioneering nickel-manganese-cobalt (NMC) cathode material and encapsulated them with a sulfur-containing polymer called PEDOT.
According to the scientists, it is this polymer that provides the cathode with a layer of protection from the battery’s electrolyte as the battery charges and discharges.
The PEDOT coating had the ability to penetrate to the cathode particle’s interior, adding an additional layer of shielding.
This is quite contrary to how traditional battery coatings function. Most coatings available today only protect the exterior surface of the micron-sized cathode particles and leave the interior vulnerable to cracking,
The PEDOT coating is also said to prevent the chemical interaction between the battery and the electrolyte.
It however allows for the necessary transport of lithium ions and electrons that the battery requires in order to function.
The coating further prevents another reaction that causes the battery’s cathode to deactivate.
In this reaction, the cathode material converts to another form called ‘spinel,’ which is basically a magnesium aluminium mineral.
“The combination of almost no spinel formation with its other properties makes this coating a very exciting material,” contends Amine.
The PEDOT material has also showcased its ability to prevent oxygen release – a major factor for the degradation of NMC cathode materials at high voltage.
It was further found to be able to suppress oxygen release during charging, which leads to better structural stability and also improves safety.
The coating could be likely scaled up for use in nickel-rich NMC-containing batteries, opines Amine.
Such batteries could either run at higher voltages – thus increasing their energy output – or have longer lifetimes, or both, says Amine.
Image and content: Argonne National Laboratory