A team led by Sandia National Laboratories‘ researcher Jianyu Huang has succeeded in creating the world’s smallest battery at a research facility belonging to the Department of Energy. The battery is in fact so small that it was formed inside a transmission electron microscope and consists of a single nanowire (as the battery’s anode) which is one seven-thousandth the thickness of a human hair!

The microscopic battery’s anode is made from a single nanowire  just 100 nanometers wide and 10 micrometers long, in comparison, its lithium cobalt oxide cathode is huge at three millimeters in length. While it may not resemble a battery, the Sandia team have created a single tin oxide (SnO2) nanowire that will help scientists discover what occurs inside lithium-ion storage devices and how they charge and discharge.

“What motivated our work,” says Huang in a press release, “is that lithium-ion batteries [LIB] have very important applications, but the low energy and power densities of current LIBs cannot meet the demand. To improve performance, we wanted to understand LIBs from the bottom up, and we thought in-situ TEM could bring new insights to the problem.”

He continued that the most fascinating part of work, which is published in the latest journal of Science, is the discovery of how the nanowire anode increases its length during charging. It contradicted the popular belief that the battery actually increased its diameter during that time. This information means that battery designers could be able to create a model that would not be capable of  ‘short circuiting’, therefore providing them with the information the need to teach battery designers how to avoid short-circuits in their newest models. Huang’s team also discovered an area where a high density of mobile dislocations caused the nanowire to bend and wiggle in the face of lithium ions. The team called this the “Medusa front”.

“These observations also prove that nanowires can sustain large stress (>10 GPa) induced by lithiation without breaking, indicating that nanowires are very good candidates for battery electrodes,” said Huang. “No one had ever seen either before, but our observations tell battery researchers how they are generated, how they evolve during charging, and offer guidance in how to mitigate them. This is the closest view to what’s happening during charging of a battery that’s been achieved so far.”

While Huang’s battery only has a current of a picoampere (a millionth of a millionth of an ampere) and 3.5 volts, it could potentially be used to power medical nano devices and aid in life-saving surgeries.

+ Sandia National Laboratory

Via Eureka! Alert