Valorization of hazelnut shell waste biomass into sustainable carbons for energy storage applications

In the last decades, the use of biochar has been receiving increasing attention for the development of electrochemical energy storage devices. In this work, the waste hazelnut shell biomass, a low cost and abundant agriculture residue within our territory, was valorized as feedstock for the synthesis of alkali-derived activated carbons, which were properly characterized and electrochemically tested, in the perspective of their use as new electrode material in energy storage applications. Two activated carbons have been identified as promising materials for this application and their electrochemical performances were further improved by including a doping step with copper (I) oxide, achieving the best specific capacitance of 123 F/g. Moreover, one of the two most promising activated carbons was tested in an EDLC symmetric device outperforming, at low power rates, reference materials in terms of specific energy density, reaching the value up to 40 Wh/kg, due to its remarkable specific capacitance of 55 F/g. In summary, this work proposes a sustainable and low energy demanding approach to transform waste biomasses into high value activated carbon materials for energy storage applications. The strategy not only promotes the reuse and valorization of hazelnut shell waste biomass, but it also supports a circular model with promising environmental and economic advantages.