Tuesday, September 14, 2010

Looking Inside Lithium Ion Batteries

Lithium-ion batteries are used to power electronic devices such as mobile phones (cell phones) and are widely used because of their low weight, high energy density and recharging ability. If scientists could see the batteries working at the nanoscale, observing the functionality of the batteries at the level of a single grain or an extended defect, they could determine what makes one battery work and another one fail.
Department of Energy's Oak Ridge National Laboratory (ORNL) scientists have developed a new type of scanning probe microscopy called electrochemical strain microscopy (ESM) to examine the movement of lithium ions through a battery's cathode material. They showed that the lithium ion flow could concentrate along grain boundaries, leading to cracking and battery failure.

Reference:
N. Balke, S. Jesse, A. N. Morozovska, E. Eliseev, D. W. Chung, Y. Kim, L. Adamczyk, R. E. GarcĂ­a, N. Dudney, S. V. Kalinin. Nanoscale mapping of ion diffusion in a lithium-ion battery cathode. Nature Nanotechnology, 2010; DOI: 10.1038/nnano.2010.174


Further Reading:
Batteries
Galvanic Cells
Oxidation and Reduction

Study Questions
  1. What is the difference between a battery and an electrochemical (galvanic or voltaic) cell?
  2. Is the lithium-ion battery described in the article an example of a primary or secondary cell? Explain your answer.
  3. Draw a sketch of a galvanic (voltaic) cell. Label the anode, cathode, and electrolyte. Clearly show the direction of electron flow through the cell.
  4. Explain how the galvanic (voltaic) cell above could be recharged.
  5. In the lithium-ion battery in the article above, will lithium ions be produced at the anode or the cathode while the battery is being discharged?
  6. Describe the movement of lithium ions in the lithium-ion battery described above during the process of recharging the battery.

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