Korean scientists have utilised semiconductor technology to effectively increase the safety of electric vehicle batteries which can cause explosions and fires.
The research team from the Korea Institute of Science and Technology (KIST) has successfully demonstrated that semiconductor technology can inhibit the danger of explosions and fires in lithium-ion (Li-ion) electric vehicle batteries, a growing concern in the green automotive industry.
The team has efficaciously mitigated the growth of dendrites – combustion causing crystals with multiple branches that instigate electric vehicle battery fires when they construct protective semiconducting passivation layers on the surface of Li electrodes.
In the charging process of Li-ion electric vehicle batteries, Li-ions are transported to the anode, where they are deposited on the surface as Li metal; it is at this stage where destructive dendrites are formed. Uncontrollable volumetric fluctuations are caused by these Li dendrites, resulting in reactions between the solid electrode and the liquid electrolyte, initiating fires and subsequently reducing battery performance and safety.
To combat this severe problem of dendrite growth, the researchers exposed fullerene (C60) to plasma, which resulted in semiconducting passivation carbonaceous layers between the Li electrode and the electrolyte forming. Fullerene is a highly electronic conductive semiconductor material that is a specific form of carbon where 60 carbon atoms are comprised to form single and double bonds in a pentagonal shape. Due to the semiconducting passivation carbonaceous layers, Li-ions are able to permeate through whilst simultaneously obstructing electrons due to the generation of a Schottky barrier. This prevents the ions and electrons from interacting on the electrode surface and inside, eliminating the formation of dendrites grown from Li crystals.
The researchers tested the stability of the electrodes with the semiconducting passivation carbonaceous layers by employing Li/Li symmetric cells in extreme electrochemical environments in which electrodes demonstrate solidity for a maximum of 20 charge/discharge cycles. The novel electrodes demonstrated enhanced stability, suppressing Li dendrite growth for up to 1,200 cycles. Furthermore, by using a lithium cobalt oxide (LiCoO2) cathode in tandem with the new electrode, 81% of the battery capacity was maintained throughout 500 cycles, a 60% improvement on conventional Li electrodes.
Dr Joong Kee Lee, the leader of the research, said: “The effective suppression of dendrite growth on Li electrodes is instrumental for improving battery safety. The technology for developing highly safe Li-metal electrodes proposed in this study provides a blueprint for the development of next-generation batteries that do not pose a fire risk.
“We aim to make the fabrication of the semiconducting passivation carbonaceous layers more cost-effective by substituting fullerene with less expensive materials.”