Figure 1. Schematic of the proposed approach to remove toxic Cr(VI) using a cost-effective porous carbon and further integrate the Cr-containing porous carbon as the anode for lithium battery applications.

Figure 2. (a) Douglas fir leaves that are available in Oregon. (b) Battery half-cell test showing the discharge capacity and efficiency.

AGRICULTURAL RESEARCH FOUNDATION INTERIM REPORT

FUNDING CYCLE 2018 – 2020

TITLE: From Wastewater Materials to High-Energy-Density Lithium-Ion Batteries RESEARCH LEADER: Zhenxing Feng COOPERATORS: EXECUTIVE SUMMARY: OBJECTIVES: The goal of this proposal is to design an environmental benign process that can utilize cost-effective and highly porous carbon materials to effectively remove Cr(VI) in the wastewater, and subsequently the Cr-containing carbon can be easily separated from the wastewater to be engineered as the electrode for high-energy-density lithium-ion battery applications. PROCEDURES: The first step of this proposal is to fabricate cheap porous carbon. Instead of purchasing from commercial carbon products (e.g., graphite), we will use fish scale or leaves, which are quite abundant in seafood markets and/or Oregon, for hierarchical lamellar porous carbon. We expect to obtain highly porous structure in carbon materials, which can act as the excellent template to adsorb Cr(VI). Then the adsorption capability of carbon will be tested. The results will be compared with commercial graphite and activated carbon. To improve the adsorption capability, functional group (e.g., nitrogen-group) may be added on FHLC. The composition of the functional groups will be examined by X-ray photoelectron spectroscopy (XPS) at Oregon State University (OSU), and its effects on Cr adsorption will be verified using isotherm models described above. The Cr-Fe-FHLC waste will then be used as the anode to be integrated in a lithium-ion battery using LiCoO2 as the cathode and LiPF6 as the electrolyte, as proposed in Figure 1. We expect that this new anode materials generated from the wastewater treatment will have comparable performance as shown in our preliminary results using PEI-NPC. SIGNIFICANT ACCOMPLISHMENTS TO DATE: We have gathered Douglas fir leaves (as shown in Figure 2a) that are abundant in Oregon, and used them to generate hard carbon by carbonization at 1300 oC. These carbon materials were then made as anode materials in LIB for half-cell test (4.2 V output voltages). The capacity is ~200

mAh/g and the cycling performance is comparable with commercial carbon as illustrated in Figure 2b. We also started the analysis the adsorption capability of carbon for Cr(VI). The Cr-contained carbon will be also made as anode materials for battery tests and be compared with pristine carbon and commercial graphite. We also tested the similar idea in commercial carbon materials by using polyethylenimine (PEI) modified nitrogen-rich porous carbon (PEI-NPC) for Cr(VI) absorption and battery anode. It not only shows strong adsorption and conversion capability for Cr(VI), but also exhibited much improved battery capacity (943.5 mAh/g). The results have been published in Materials Letters, 219, 2018, 100-103. We will expect the hard carbon generated from Oregon leaves can perform well but are more economical compared to PEI-NPC. ADDITIONAL FUNDING RECEIVED DURING PROJECT TERM: FUTURE FUNDING POSSIBILITIES: This topic fit the themes in NSF, CBET, and could obtained jointed support from Chemical Process Systems Cluster and Environmental Engineering and Sustainability Cluster. With more preliminary results, I will solicit funding in this Division.