Among the biggest challenges that electric aircraft developers are facing today is the limitations of battery technologies. Unless scientists come up with new ways to make smaller and lighter batteries that hold more charge for longer periods of time, electric aircraft will only be able to make short, regional flights before needing to recharge.
To make matters more complicated, batteries degrade over time, reducing the amount of charge they can hold and shortening the battery life. Just like the lithium-ion batteries in cellphones and electric cars wear out every few years, electric aircraft using today’s battery technology will need their aging batteries replaced on a regular basis. However, new research suggests that a minor modification to existing lithium-ion batteries could extend their lifespan, reducing the need for frequent battery replacements.
In a recent study published in the Journal of Materials Chemistry A, researchers at the Gwangju Institute of Science and Technology (GIST) in South Korea say they have come up with a new way to make lithium-ion batteries last longer. To do this, the researchers added an elastic web-like structure to the anode, or the negatively charged electrode on one side of a battery cell.
When a lithium-ion battery is discharging, or providing electric current, lithium atoms stored in the anode are released and flow toward the cathode, or the positive electrode on the opposite side of the battery cell. During this process, the lithium atoms shed their outer electrons and become positively charged lithium ions. Those freed electrons, which have a negative charge, then move toward the cathode. The opposite happens when a battery is recharged; lithium ions are released from the cathode and move back to the anode.
The anode contains nanoparticles that bind with lithium, and over time, those nanoparticles tend to crack and cluster together, reducing the anode’s capacity to store the lithium atoms. This, in turn, reduces a battery’s charge capacity and shortens the battery life.
GIST researchers were able to slow down that degradation process by reinforcing the nanoparticles in the anode with a web-like structure, which they created by injecting a graphene oxide solution. The solution dried to form a web between the nanoparticles, holding the nanoparticles together to prevent cracking without impeding their ability to bind with lithium. With the added structural stability, the reinforced battery was able to retain most of its charging capacity after 500 charging/discharging cycles.
“The structure retained a high storage capacity of 1566 mA h g 1 after 500 cycles and showed 91% coulombic efficiency, which relates to the battery life. This could pave the way for electric vehicles that enable us to drive long distances on one time charging,” Hyeong-Jin Kim, one of the co-authors of the new study, said in a university statement. In turn, the results of the study could also pave the way for electric aircraft to make longer flights and require less frequent battery replacements.
For this study, the researchers used a conventional lithium-ion battery with an anode consisting of silicon nanoparticles. However, the researchers said the same method could be used to improve the lifespan of the anodes in other types of batteries as well, such as those that contain tin, aluminum, and magnesium.