Researchers from Japan’s Okinawa Institute of Science and Technology (OIST) have taken the nanoparticle approach to develop a novel supercharging battery technology.
The researchers built an anode on nanostructured layers of silicon – unlike the multi-layered cake used in current Li-ion battery packs– to preserve the advantages of silicon while preventing physical collapse.
Silicon offers great advantages over carbon graphite for lithium batteries in terms of capacity. Six atoms of carbon are required to bind a single atom of lithium. On the other hand, one atom of silicon can bind four atoms of lithium at the same time, multiplying the battery capacity by more than 10-fold.
Nevertheless, capturing that many lithium ions also means that the volume of the anode swells by 300% to 400%, leading to fracturing and loss of structural integrity. OIST hopes to combat this with its new battery technology.
“The goal in battery technology right now is to increase charging speed and power output,” explained Dr. Marta Haro Remon, first author of the study. “While it is fine to charge your phone or your laptop over a long period of time, you would not wait by your electric car for three hours at the charging station.”
The idea behind the new anode in OIST’s Nanoparticles by Design Unit is the ability to precisely control the synthesis and the corresponding physical structure of the nanoparticles. Layers of unstructured silicon films are deposited alternatively with tantalum metal nanoparticle scaffolds, resulting in the silicon being sandwiched in a tantalum frame.
“We used a technique called Cluster Beam Deposition,” continued Dr. Haro. “The required materials are directly deposited on the surface with great control. This is a purely physical method, there are no need for chemicals, catalysts or other binders.”
The outcome of this research, led by Prof. Sowwan at OIST, is an anode with higher power but restrained swelling, and excellent cyclability – the amount of cycles in which a battery can be charged and discharged before losing efficiency.
Though the OIST design is still in a proof-of-concept stage, the technology does open doors to numerous opportunities for improving a battery’s capacity and power.
“It is a very open synthesis approach, there are many parameters you can play around,” commented Dr. Haro. “For example, we want to optimize the numbers of layers, their thickness, and replace tantalum metal with other materials.”
Image credits and content: Okinawa Institute of Science and Technology (OIST)