Standardization challenges of biomass-based carbon electrodes for supercapacitors

Abstract

Biomass-derived carbon is intensively researched as an electrode for electrochemical capacitors (supercapacitors) owing to the sustainability concerns; however, the universality is questioned primarily because of the dependence of the chemical variance of the precursor on the species, part, and geographical location of their sourcing and consequent carbon purity. Besides, lack of guidelines for measurement and reporting lead to inconsistent data in the open literature. This article seeks the characteristics of biomass carbon derived electrochemical capacitors, guidelines for their measurements and reporting, and efforts needed for their universal acceptance as a high impact science. Other topics addressed besides chemical purity are (i) problems associated with single electrode capacitance measurements and their insignificance in the charge storability of a full device, (ii) inaccuracies in the reporting of energy density using the equation derived by assuming linear variation of charge with applied potential, and (iii) loss of charge at no load condition, known as self-discharge, and their significance in practical applications. Addressing these issues and streamlining the research towards developing biomass carbon as a high pure industrial material are expected to contribute diverse areas of carbon functionality and to the sustainability agenda.