New cathode coating makes lithium-ion batteries even more efficient and safer

It fully and completely protects each particle of the cathode - inside and out.

Protective coating for battery electrodes is an important aspect of ongoing efforts to improve the performance of lithium-ion batteries (LIBs). American scientists have unveiled their new project, make lithium-ion batteries safer and more durable.

As a result of three years of research, a team of scientists from the U.S. Department of Energy’s (DOE) Argonne National Laboratory, in collaboration with the Hong Kong University of Science and Technology (HKUST), has announced the development of a new particle-level cathode coating that should extend the life of lithium-ion batteries and increase their safety.

The new coating, called PEDOT, is made with a conducting polymer called poly (3,4-ethylene dioxythiophene) (PEDOT). It fully and completely protects each particle of the cathode – inside and out – from reactivity with the electrolyte.

Lithium-ion batteries, although currently used in many electronic devices, are not ideal. One of the key problems of lithium-ion batteries is that a charged cathode at high voltage produces oxygen, which reacts with an electrolyte.

As a result of this, a film is formed on the surface of the cathode, which reduces the amount of energy transferred between the electrodes. This reduces the performance of the entire battery.

To solve this problem, a special coating is applied to the cathode. For more than 15 years, lithium-ion batteries have been using a cathode coating technology that only represents a partial coating of them. It only covers the small part of the outside of the cathode particle and does not protect the cathode when operating at a high voltage or at high temperature, and the battery continues to degrade.

The PEDOT coating itself is applied through a gas, using an oxidative chemical vapor deposition technique. It can cover each individual particle of the cathode, that is, in a complete and not partial way like the current coatings.

During the tests, PEDOT was able to increase the operating voltage of lithium-ion batteries to 4.6 V compared to 4.2 V on existing lithium-ion batteries, while maintaining the same level of wear as without coating.

Although this is only a 15% improvement, the researchers are confident that this will lead to a significant reduction in the cost of batteries and increase their service life.

This would increase the driving range of electric cars and boost the battery life of cell phones and laptops, ultimately changing the way we live,” said Khalil Amine, Argonne distinguished fellow. However, it is too early to talk about the commercial application of technology.

Journal Reference:
  1. Boosting superior lithium storage performance of alloy‐based anode materials via ultraconformal Sb coating–derived favorable solid‐electrolyte interphase. DOI: 10.1002/aenm.201903186
  2. Building ultraconformal protective layers on both secondary and primary particles of layered lithium transition metal oxide cathodes. DOI: 10.1038/s41560-019-0387-1

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