Synthetic Graphite from Biomass as Anode Material for 6T Batteries

Farad Power Inc. proposes to develop and commercialize a Li-ion battery (LIB)- grade graphite from an agricultural waste extract for use in 6T batteries for the US Navy. ĀSpecifically, furan chemicals (furfural C5H4O2 and furfuryl alcohol C5H6O2) are extracted from the hemicellulose component of plant-based biomass. ĀThese chemicals are pure, cheap, and abundant. We have developed a patented process to polymerize these furan chemicals, followed by carbonization at 1000oC to make hard carbon. ĀThese are partially graphitized, with significant d002 peaks in their X-ray diffraction (XRD) patterns (the d002ĀXRD peak is the primary peak identifying graphite).Ā These hard carbons also have good electrochemical performance (280 mAh/g capacity at 1C rates) and excellent cycle life (88% capacity retention after 1000 cycles). We propose to use these carbonized materials as precursors for LIB-grade graphite synthesis. ĀThe existing synthetic graphite manufacturing process used by the industry today graphitizes a carbonized material derived from petroleum pitch or coal-tar pitch. ĀFollowing carbonization, these pitch-based materials are still amorphous (no evidence of d002 peaks in their XRD patterns). ĀThe graphitization process thus requires a prolonged soaking at elevated temperatures (3000oC). ĀSome of these processes can last up to 72 hours ¢ making the graphitization of pitch-derived materials a highly energy-intensive operation. ĀFurthermore, due to the duration of the process, graphitization of pitch-based materials will have a large æcarbon footprintÆ. Also, manufacturing plants must be strategically located in low-cost areas (specifically for electricity supply). We have performed some initial graphitization studies on our furan-based carbons. ĀHeating for 1 hour at 3000oC resulted in a significant change of the d002 XRD peak ¢ signifying a substantial increase in the degree of graphitization. ĀElectrochemical testing with a SiOx powder additive (in a 2:1 ratio) resulted in a capacity of >700 mAh/g, with excellent stability over 20 cycles. We are thus proposing to graphitize our hard carbons using different heating profiles, to identify the most effective version for full graphitization with an LIB anode capacity of >350 mAh/g. ĀPhase I BASE will screen samples from different heating profiles (including temperatures of 2500oC & lower). ĀXRD and 1/2 cell testing (< 5 cycles) will be used as the screening criteria. ĀDuring the Phase I OPTION period, we propose to graphitize several batches using the most promising profile ¢ to test the repeatability of the process. ĀAt this stage, we plan to also test full cells over 300 cycles to evaluate cycling stability. This will set us up for Phase II, where we propose to supply furan-derived graphite to our 6T battery partners for evaluation. ĀPhase II will also use capacity-enhancing additives (SiOx) to improve the overall performance of the 6T battery. ĀPlans for commercialization will also be developed.