A rechargeable, lithium-based battery has been formed inside a transmission electron microscope (TEM) by Jianyu Huang and co-workers, Sandia National Laboratories, USA. This allowed them to study the anode’s characteristics and enable observation of the charging and discharging of a battery in real time and at atomic scale resolution.

The TEM experiment used a low–vapor pressure ionic liquid electrolyte to image the SnO₂ nanowire electrode. Upon charging, a reaction front propagated progressively along the nanowire, causing the nanowire to swell, elongate, and spiral. A ~250 % volume change was observed with 90 % elongation of the nanowire. No fracturing of the nanowire was seen at practical charging rates.

The low energy and power densities of current lithium ion batteries cannot meet demand, but nanowire-based materials in lithium ion batteries offer the potential for improvement. This investigation into their operating properties should improve new generations of plug-in hybrid electric vehicles, laptops and cell phones.

• In Situ Observation of the Electrochemical Lithiation of a Single SnO₂ Nanowire Electrode
  J. Y. Huang, L. Zhong, C. M. Wang, J. P. Sullivan, W. Xu et. al.,
  Science 2010, 330, 1515–1520.
  DOI: 10.1126/science.1195628