Biochar is a developing technology because it can be used as raw material for making battery anodes. This technology is widely used in electronic devices such as cell phones, camera recorders, and laptops.
Seeing this opportunity, four students of Chemical Engineering Universitas Brawijaya (UB) research and develop the potential of biochar made from coconut shell as a raw material for forming anode material in lithium-ion batteries.
Lithium-ion battery is one type of battery that is widely used in electronic equipment. Even recently lithium-ion batteries are being developed for electric cars.
In addition to being rechargeable, lithium-ion batteries have a long cycle life, large storage capacity, and are of course environmentally friendly.
According to the research team, coconut shell biochar has the potential to be used as anode for lithium-ion batteries because it has a high specific storage capacity of 372 mAh/g and produces battery cells with a high energy density of 0.1 A/g.
Coconut shell material itself has a good pore structure with a high surface area, is easily found in nature and is available in large quantities.
“In terms of performance, it is able to compete with the performance of conventional lithium-ion batteries with a discharge power of 2.79 Volts. Meanwhile, if viewed from an economical point of view, the anode material from biochar is cheaper and at the same time utilizes coconut shell waste so that it has more use value,” said Team Leader, Dyah Nurfitri Solikhah.
She continued, this coconut shell biochar composite has advantages in terms of graphite. Theoretically, the graphite capacity is only 350 mAh/g and cannot meet the growing demand for high-performance Lithium-ion batteries.
However, graphite is a good conductive material, so it is still widely applied as an electrode for lithium-ion batteries.
Joined in the Alkalithium Team, Dyah and his three colleagues; Aditya Bayu Pratama, Salsabila Rahmah, and Tiara Shifa Hartantri purified biochar before it was applied as an anode component of lithium-ion batteries.
“The purification method is called alkaline roasting,” said this 2019 student.
The alkaline roasting method uses alkali in the form of a base, that’s NaOH which will then be mixed with biochar from coconut shells and roasted at a certain temperature.
This method was chosen because biochar from coconut shells has the most impurities in the form of silica which can react with NaOH base to become sodium silicate which is soluble in water.
Besides silica, other impurities are metal oxide compounds. Metal oxides are easily soluble in acids.
The acid commonly used in the metal oxide dissolution process is H2SO4, where this process is also known as leaching. Dissolving metal oxide will open the pores on the carbon.
“The method used has the potential to remove impurities in biochar; silica and metal oxide compounds,” she explained.
Representing the team, she hopes that the research can contribute the technical data to be applied as applications in the development of Lithium-ion batteries and can provide solutions in the manufacture of Lithium-ion batteries that have a larger electric current storage capacity so as to improve battery performance.
With the guidance of Supriyono, S.T., M.T., the team will fight to be able to represent UB in the 34th National Student Science Week (PIMNAS) October 2021. (humasft).