Tech Briefs Magazine - April 2021 - 41

two supercapacitor electrodes. The material is available in abundance and is safer
compared to other transition metal
oxides, like ruthenium or zinc oxide, that
are popularly used for making electrodes;
however, manganese dioxide suffers from
lower electrical conductivity.
Past research has shown that lignin -
a natural polymer that glues wood fibers

together - used with metal oxides enhances the electrochemical properties of
electrodes. There have been few studies
looking into combining manganese dioxide and lignin to leverage both of their
useful properties.
To create the electrode, the researchers
treated purified lignin with a commonly
available disinfectant called potassium per-

A prototype of the green supercapacitor. (Image courtesy of Hong Liang)

manganate. They then applied high heat
and pressure to initiate an oxidation reaction that results in the breaking down of
potassium permanganate and the deposition of manganese dioxide on lignin.
Next, they coated the lignin and manganese dioxide mixture on an aluminum
plate to form the green electrode. Finally,
they assembled the supercapacitor by
sandwiching a gel electrolyte between the
lignin-manganese dioxide-aluminum electrode and another electrode made of aluminum and activated charcoal.
Upon testing the green electrode, they
found that the supercapacitor had very
stable electrochemical properties. In particular, the specific capacitance (the ability of the device to store an electrical
charge) changed little, even after thousands of cycles of charging and discharging. Also, for an optimal lignin-manganese dioxide ratio, the specific capacitance was observed to be up to 900 times
more than what has been reported for
other supercapacitors.
For more information, contact Amy Halbert
at ahalbert@tamu.edu; 979-458-4243.

Extracting Bioproducts from Plants for Biofuels
Biofuels can achieve cost parity with petroleum fuels.
Lawrence Berkeley National Laboratory, Berkeley, California

iofuels are an important part of the
broader strategy to replace petroleum-based gasoline, diesel, and jet fuels
that we use today; however, biofuels have
so far not reached cost parity with conventional petroleum fuels.

One strategy to make biofuels more
competitive is to make plants do some of
the work themselves. Scientists can engineer plants to produce valuable chemical
compounds, or bioproducts, as they grow.
Then the bioproducts can be extracted

from the plant and the remaining plant
material can be converted into fuel. When
produced in the plant itself, bioproducts
can help reduce the cost of the resulting
biofuel. But one important part of this
strategy has remained unclear - exactly

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Tech Briefs Magazine - April 2021

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