In situ graphitized hard carbon xerogel: A promising high-performance anode material for Li-ion batteries

To address the challenges of capacity fading and poor electronic conductivity of hard carbons as anode in Li-ion batteries (LIBs), we report here the catalytic graphitization of resorcinol-formaldehyde xerogel (RFX)-derived hard carbon via a single-step synthesis by incorporating two transition metal catalysts (Co and Ni) with different loadings (5 and 10%) at a modest temperature of 1100 degrees C. Loading of both the catalysts affects the extent of graphitization and other physiochemical properties that have a direct influence on the anodic performance of as graphitized RFX-derived hard carbon. A 10% Ni catalyst in RFX-derived carbon induces the highest degree of graphitization of 81.4% along with partial amorphous carbon and nickel phases. This improved crystallinity was conducive enough to facilitate rapid electron and Li-ion transfer while the amorphous carbon phase contributed to higher specific capacity, resulting in overall best anodic performance as ever reported for RFX-derived carbon. A specific capacity of 578 mAh/g obtained after 210 cycles at 0.2 C with coulombic efficiency greater than 99% confirms the potential of graphitized RFX-derived carbon as an anode for high-performance LIBs.