Somehow it develops that you can endlessly monitor not only the flame of the fire and running water, but also research in the field of improving lithium-ion batteries. Among the countless ways to improve lithium-containing batteries, each of the scientists finds his own way. Even if none of these paths turns into a wide highway, all together they will, in one way or another, lead to better and more capacious batteries.
A group of researchers from the Argonne National Laboratory (USA) and Hong Kong University of Science and Technology (HKUST) proposed their own option to improve lithium-ion batteries. Scientists have focused on improving the quality and reliability of the cathode of batteries. And they did it.
The cathodes of lithium-containing batteries during operation and especially in critical operating conditions at elevated temperatures or with increasing voltage emit excess oxygen. Oxygen reacts with the electrolyte and forms an oxide film on the surface of the cathode, which degrades the characteristics of the batteries – it reduces the permeability of lithium ions and electrons, which reduces the energy capacity of the battery.
In the production of lithium-ion batteries, an unpleasant feature of the interaction of cathodes and electrolyte is taken into account, which forces manufacturers to cover the cathodes with various protective films. Unfortunately, this still slows down the movement of lithium ions, reducing the efficiency of the batteries. In addition, since the coating does not cover the entire surface of the cathodes, degradation can still occur, which is especially pronounced in extreme operation modes.
During the experiments, the researchers selected a promising polymer coating for the cathodes in the form of a conductive polymer PEDOT. The polymer is deposited on the cathodes from the vapor phase and completely covers its surface. But most importantly, the PEDOT coating does not interfere with the movement of ions, which means maintaining the capacitive and energy parameters of the batteries. Moreover, the battery voltage was increased from 4.2 V to 4.6 V without signs of degradation during long-term operation of the batteries.
The new process technology promises to make the production of lithium-ion batteries easier and cheaper, and will also provide them with a longer operating time, which is welcome.
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