Spruce Hard Carbon Anodes for Lithium-Ion Batteries

In this work, lithium-ion battery full-cells based on spruce-derived hard carbon anodes and an electrochemical pre-lithiation method are presented in combination with a detailed analysis of full-cell operation and the lithiation state. The physical and electrochemical properties agree well with those of previous biomass-derived hard carbon anodes. However, low initial coulombic efficiencies of 65 % represent one of the major challenges of the developed anodes with respect to full-cell operation. To counteract the initial lithium loss, in-situ electrochemical pre-lithiation was conducted, allowing battery operation in the same cell setup without reassembly. Consequently, significantly increased capacities, cycle life, and first cycle coulombic efficiency were obtained in comparison to untreated anodes (195 mAh/g versus 150 mAh/g, state of health (SOH) 80 after 150 cycles versus 70 cycles, and 90 % versus 65 %). In summary, spruce-based hard carbon has the potential to be an environmentally friendly alternative to standard graphite.