Well not quite yet...but science and
engineering is one set closer to making it a reality. Announced this
week in Nature, the University of Huston has successfully replaced
the cobalt used at the cathode with purpurin, an organically derived
dying agent from the Madder family of plants.
Below is a series of schematic diagrams
and images taken from the paper showing the molecular structure of
purpurin and the way that it can be chemically altered to become a
store of lithium ions in a process known as lithiation. (a) Schematics 1, 2 and 3 show the sequence of lithiation. (b) Image 1, unaltered purpurin and image 2, chemically lithiated purpurin. Test have
shown that chemically lithiated purpurin has very good reversible lithium ion
storage properties.
But the implications resulting from the
use of organically derived chemicals at the cathode of L-ion
batteries goes far beyond replacing a toxic chemical. Traditionally,
cobalt ions and lithium are combined under high temperatures to form the cathode.
Purpurin, on the other hand, can be lithiated at room temperatures
using a bath of lithium salts. The other major benefit of using a
more organic battery is the reduction in the energy required to
safely recycle the product. Currently, combined manufacturing and
recycling costs approximately 70kg of carbon dioxide per KWH of battery power (1).
In the future this value could be dramatically reduced.
Image from: http://evergreenknits.blogspot.co.uk/2010/06/growing-madder.html
Source: (1) Rice University
