Scientists at Stanford have
developed novel batteries that
can be charged on the basis of
difference of salt content
between fresh water and salt
water. These batteries use new types of electrodes made of
nanoscale rods of manganese
dioxide and silver resulting in up
to a hundred fold increase in
surface area. The electrodes are
alternatively dipped in fresh and salt water to produce electrical
power. The method comprises
charging the battery in fresh
water, and then replacing the
fresh water with salt water. This
leads to a hundred fold increase in the ions, so that the battery
can discharge at a much greater
voltage, resulting in production
of electricity.