Biochar or activated biochar for batteries? Unveiling the electrochemical potential of hardwood waste in lithium and sodium-ion systems

Abstract

The detrimental environmental impacts of fossil fuels, particularly CO2 emissions, necessitate the development of clean energy technologies such as advanced energy storage devices. This study investigates the use of biochar derived from hardwood waste and its activated form as anodes in lithium-ion (LIBs) and sodium-ion batteries (SIBs). Our findings indicate that steam activation of biochar has a minimal impact on improving its performance in LIBs. Surprisingly, non-activated wood biochar exhibits superior performance in SIBs, with nearly double the capacity at 0.5 A/g (72 vs. 33 mA h/g) over 850 cycles. This research underscores the importance of optimizing material properties, such as graphitic layer d-spacing, specific surface area, graphitization order, and elemental composition, to improve battery performance across different chemistries. It is crucial to note that activated biochar production demands significant energy, gas, and chemical inputs, leading to increased resource consumption and costs. Therefore, unprocessed biochar presents a more viable and environmentally friendly alternative. This study advocates a comprehensive understanding of biochar properties and their impact on electrochemical performance, emphasizing the engineering of biochar to meet specific application needs rather than focusing solely on feedstock types.