Authors:

Adam Harper

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Rice hull ash (RHA) is an agricultural waste product produced when rice hulls are combusted for energy, which consists of high-surface-area SiO, (90 wt%) and carbon (10 wt%). Previous work found that RHA contains an amorphous structure of carbon known as hard carbon (HC). HC is a promising alternative anode material to graphite in lithium-ion batteries due to its high specific capacity (~320 mAh g™), though it may exhibit lower first cycle efficiencies (~65%). Our work aims to optimize the specific capacity and first cycle efficiency of silica-depleted rice hull ash (SDRHA) anodes in half-cells by adjusting silica content and heat treatment in N,. RHA was depolymerized to form SDRHA, which was used to prepare electrodes and assemble Li/SDRHA half-cells. We found that 50 wt.% SiO, SDRHA half-cells showed the best combination of specific capacity normalized to carbon (300 mAh g™ at 1 C) and first cycle efficiency (~41%). In addition, heat-treatment in N, at 800°C for 2 h increased first cycle efficiency (~50%) while maintaining similar specific capacities. This improvement can be attributed to heat-treatment restructuring of the HC, which reduces irreversible lithium loss. These results reveal that tuning silica content and carbon structure improves the electrochemical performance of SDRHA as a greener high-capacity anode material to replace graphite, which emits 5-10 tons CO, per ton produced. References . [1] Yu, M., Wang, M., Indris, S., Manassa, J., Stangel, A., Hovden, R., & Laine, R. M. (2024). An Unexpected Source of Hard Carbon, Rice Hull Ash, Provides Unexpected Li + Storage Capacities. Advanced Sustainable Systems, 9(2). https://doi.org/10.1002/adsu.202400667 SCO OHO OHS HS OOH OOS OSS OOOH OOM LS OCSCOHOHGOOT OOOH OOOO OCOOCOE | DDDDDIDIFDIDHIDIDSIDDIHSDDDIDDDIDIDSIIDIIDBADIDISHSBD

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Chicago Area Undergraduate Research Symposium

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Co-authors:

Adam Harper