The present work elucidates facile one-pot synthesis from biomass forestry waste (Norway spruce bark) and its chemical activation yielding high specific surface area (S _BET) biochars as efficient lithium- and sodium-ion storage anodes. The chemically activated biochar using ZnCl₂ (Biochar-1) produced a highly mesoporous carbon containing 96.1% mesopores in its structure as compared to only 56.1% mesoporosity from KOH-activated biochars (Biochar-2). The latter exhibited a lower degree of graphitization with disordered and defective carbon structures, while the former presented more formation of ordered graphite sheets in its structure as analyzed from Raman spectra. In addition, both biochars presented a high degree of functionalities on their surfaces but Biochar-1 presented a pyridinic-nitrogen group, which helps improve its electrochemical response. When tested electrochemically, Biochar-1 showed an excellent rate capability and the longest capacity retentions of 370 mA h g^-1 at 100 mA g^-1 (100 cycles), 332.4 mA h g^-1 at 500 mA g^-1 (1000 cycles), and 319 mA h g^-1 at 1000 mA g^-1 after 5000 cycles, rendering as an alternative biomass anode for lithium-ion batteries (LIBs). Moreover, as a negative electrode in sodium-ion batteries, Biochar-1 delivered discharge capacities of 147.7 mA h g^-1 at 50 mA g^-1 (140 cycles) and 126 mA h g^-1 at 100 mA g^-1 after 440 cycles.

Batteries are the backbones of the sustainable energy transition for stationary off-grid, portable electronic devices, and plug-in electric vehicle applications. Both lithium-ion batteries (LIBs) and sodium-ion batteries (NIBs), most commonly rely on carbon-based anode materials and are usually derived from non-renewable sources such as fossil deposits. Biomass-derived carbon materials are extensively researched as efficient and sustainable anode candidates for LIBs and NIBs. The main purpose of this perspective is to brief the use of biomass residues for the preparation of carbon anodes for LIBs and NIBs annexed to the biomass-derived carbon physicochemical structures and their aligned electrochemical properties. In addition, an outlook and some challenges faced in this promising area of research is presented. This review enlightens the readers with valuable insights and a reasonable understanding of issues and challenges faced in the preparation, physicochemical properties, and application of biomass-derived carbon materials as anode candidates for LIBs and NIBs.