Biomass-derived biochar for electrochemical energy storage and conversion systems: Opportunities and challenges

The worldwide usage of fossil fuels brings severe crises, including environmental degradation, energy security concerns, and resource depletion. The materials predominantly used in energy storage and conversion devices, such as carbon, are typically derived from coal and petrochemicals, with highly energy-intensive processes and contributing to environmental pollution. Consequently, there is a pressing demand for powerful and energy-dense electrochemical devices that can reduce our dependence on fossil fuels while efficiently storing energy. In this context, biomass emerges as a promising and sustainable source to produce biochar, offering abundance, affordability, and renewability. Biochar can be easily modified with different functional groups to enhance its electrochemical behavior. This review paper gives insight about the recent advancements in the application of biochar-based materials across various fields for electrochemical energy systems. It covers topics such as lithium/sodium-ion batteries, supercapacitors, hydrogen storage systems, fuel cell technologies, and emerging microbial fuel cells/ dye-sensitized solar cells. The diverse sources of biomass and the various synthesis processes used to derive biochar would be discussed. This paper also provides outline about the potential of biochar as a renewable energy source for overcoming the challenges faced due to overconsumption of fossil fuels.