are torn apart – without the need for a catalyst such as heat. Spanish
scientists at CIDETEC (Centre for Electrochemical Technologies) have
built this “Terminator” polymer with a molecular structure that is
held together with disulphide bonds. These break when the material
is cut. The bonds between the sulphur atoms rebuild if both ends are
held together. This polymer plus a liquid Indium-Gallium alloy used
as an electric conductor result in a self-healing power cable.
Researchers at the University of North Carolina have developed this
cable: if it is cut, the liquid metal at the ends hardens up. If these
ends are plugged together, the plastic and the metal merge, and the
cable looks as though it had never been cut.
Self-healing is more than an end in itself: even more efficient
batteries cannot sustain for long without an integrated repair
technology. Silicon would be the perfect substrate for storing lithium
in lithium ion batteries; this way, the storage capacity could be
increased tenfold. But the anode volume increases threefold due to
the lithium-silicon bonds (Li15Si4 or Li21Si5) when the battery is
charged and comes back to its normal size when it is discharged.
This ruptures the graphite layer, in which the material is stored.
Researchers at the Stanford University covered the graphite with a
self-healing polymer envelope that repairs the ruptures.
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