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nano technology

How batteries die

The efficiency of cell phone and notebook batteries depends on the ability of ionized lithium atoms to flow freely inside the battery. As the battery is repeatedly charged and discharged, its ions flow increasingly slower, until they stop altogether. Experiments conducted by a team led by Sarbajit Banerjee, a chemist at Texas A&M University, has shown nanometric details of this process for the first time. Analyzing a set of X-ray microscopy and spectroscopy images, the researchers observed how the lithium ions moved through nanowires of vanadium pentoxide, a material used in the experiment as a model for the inside of a conventional lithium battery (Nature Communications, June 28, 2016). They concluded that lithium ions tend to pair with electrons in the atoms that form the battery’s interior, distorting the atomic structure. These distortions are thought to slow ion traffic. The obstructions occur with increasing frequency as the battery ages, reducing the efficiency of the charging/discharging process until the device fails. Banerjee and his colleagues suggest that new materials could be designed with atomic structures that prevent interaction between the lithium ions and their electrons, thus increasing battery life and efficiency.