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Biochar, originating from biomass pyrolysis, has been proven a promising catalyst for tar cracking/reforming with great coke resistance. This work aims to evaluate various engineered biochar-based catalysts on syngas production in a biomass pyrolysis and catalytic reforming process without feeding extra steam. The tested engineered biochar catalysts include physical-and chemical-activated, nitrogen-doped, and nickel-doped biochars. The results illustrated that the syngas yields were comparable when using biochar and activated biochar as catalysts. A relatively high specific surface area (SSA) and a hierarchical porous structure are beneficial for syngas and hydrogen production. A 2 h physical-activated biochar catalyst induced the syngas with the highest H 2 /CO ratio (1.5). The use of N-doped biochar decreased the syngas yield sharply due to the collapse of the pore structure but obtained syngas with the highest LHV gas (18.5MJ/Nm 3 ). The use of Ni-doped biochar facilitated high syngas and hydrogen yields (78.2 wt % and 26 mmol H 2 /g-biomass) and improved gas energy conversion efficiency (73%). Its stability and durability test showed a slight decrease in performance after a three-time repetitive use. A future experiment with a longer time is suggested to determine when the catalyst will finally deactivate and how to reduce the catalyst deterioration.

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Sodium-ion batteries (SIBs) serve as the most promising next-generation commercial batteries besides lithium-ion batteries (LIBs). Hard carbon (HC) from renewable biomass resources is the most commonly used anode material in SIBs. In this contribution, we present a review of the latest progress in the conversion of waste biomass to HC materials, and highlight their application in SIBs. Specifically, the following topics are discussed in the review: (1) the mechanism of sodium-ion storage in HC, (2) the HC precursor’s sources, (3) the processing methods and conditions of the HCs production, (4) the impact of the biomass types and carbonization temperature on the carbon structure, and (5) the effect of various carbon structures on electrochemical performance. Data from various publications have been analyzed to uncover the relationship between the processing conditions of biomass and the resulting structure of the final HC product, as well as its electrochemical performance. Our results indicate the existence of an ideal temperature range (around 1200 to 1400 °C) that enhances the formation of graphitic domains in the final HC anode and reduces the formation of open pores from the biomass precursor. This results in HC anodes with high storage capacity (>300 mAh/g) and high initial coulombic efficiency (ICE) (>80%).

Resource-and energy-efficient biomass exploitation for green graphite production is one of the most effective strategies for satisfying graphite demand while minimizing energy consumption and carbon emissions. This study investigated green graphite production from biomass waste and its applications to establish a green graphite industry. Biomass pyrolysis and catalytic graphitization of biochar were studied first to produce green graphite. The optimized green graphite exhibited a reversible capacity of 264 mA h/g and 97% capacity retention over 100 cycles in a half-cell. Green graphite electrodes with a resistivity lower than 5 μΩ m were fabricated by using organic fraction bio-oil as a green binder. Other green graphite applications, including printing, conductive printing, pencils, and refractories, were also achieved. The overall process of graphite anode and electrode synthesis from biomass waste and short-rotation energy crops was modeled. Approx. 95 kg of battery graphite or 109 kg of metallurgical graphite electrodes can be produced per ton of biomass with low primary energy consumption and carbon footprint. Prominently, the modeling result and life cycle assessment demonstrated that, for the production of battery graphite from biomass waste, net-negative-CO 2 emissions (−0.57 kg CO 2 -eq/kg graphite powders) with net-negative-primary energy consumption (−28.31 MJ/kg graphite powders) was achieved.