Tiny batteries could herald big improvements in powering devices, according to researchers
Scientists in the US have created a working model of what they call the world's smallest battery.
The battery — with its anode a single nanowire that is one seven-thousandth the thickness of a human hair — was created in a transmission electron microscope at the Center for Integrated Nanotechnologies.
The purpose of the project was to better understand how individual nanowires behave within batteries in order to improve battery life and safety over batteries currently available.
“This experiment enables us to study the charging and discharging of a battery in real time and at atomic scale resolution, thus enlarging our understanding of the fundamental mechanisms by which batteries work,” said Sandia National Laboratories researcher Jianyu Huang.
“Lithium ion batteries [LIB] have very important applications, but the low energy and power densities of current LIBs cannot meet the demand.”
The research highlighted areas that could make battery design safer as manufacturers try to pack more power into a smaller footprint without causing short circuits.
For example, the researchers discovered that the tin oxide nanowire rod nearly doubled in length during charging — far more than its diameter increases — a fact that could help avoid short circuits.
“Manufacturers should take account of this elongation in their battery design,” Huang said. “Our observations — which initially surprised us — tell battery researchers how these dislocations are generated, how they evolve during charging, and offer guidance in how to mitigate them.”
Three dimensions pack more power
Meanwhile, Rice University scientists have claimed another breakthrough in battery technology, saying their three dimensional micro-batteries can charge faster and pack more power into a smaller footprint than conventional flat lithium-ion batteries.
"You can't simply scale the thickness of a thin-film battery, because the lithium ion kinetics would become sluggish," Pulickel Ajayan, professor in mechanical engineering and materials science and chemistry said.
"By going to 3D, we're able to deliver more energy in the same footprint," said Sanketh Gowda, a graduate student in Ajayan's lab.
According to the scientists, 3D isn't new, but the researchers realised encasing the vertical arrays of nickel-tin nanowires in a widely-used polymer called PMMA that insulates the wires enough to make the system viable, while still allowing ions to pass through.
Such batteries power new generations of remote sensors, display screens, smart cards, flexible electronics and biomedical devices, the researchers said.