Design advanced carbon materials from lignin-based interpenetrating polymer networks for high performance sodium-ion batteries

Hard carbon materials hold the most promising application among all anode materials for sodium-ion batteries because of the high storage capacity and good cycling stability. However, the low initial Coulombic efficiency limits their further commercialization. Herein, a new carbonization strategy is presented to prepare a cost-effective hard carbon material as anodes for sodium-ion batteries by pyrolyzing the interpenetrating polymer networks (IPNs) made from the mixture of biomass-derivative lignin and epoxy resin. By adjusting heat-treatment temperatures and the lignin/epoxy resin mass ratios, we can adjust the interlayer distance of carbon crystallites and defect sites for Sodium-ion storage, and thus obtain a hard carbon with a high capacity of 316 mAh g−1, a high ICE of 82%, and good rate capability (e.g., 161 mAh g−1 at 300 mA g−1), all of which are superior to or comparable to those state-of-the-art carbons reported in literatures, by the help of a large interlayer distance of 3.95 Å. Besides, a full cell with the configuration of as-prepared hard carbon anode versus air-stable O3-Na0.9[Cu0.22Fe0.30Mn0.48]O2 cathode is further demonstrated, while it presents a high ICE of 80% and an energy density of 247 Wh kganode−1 (vs. hard carbon) with good cycle performance. These excellent properties verify that our synthetic strategy is feasible, scalable and can be extended into the fabrication of various carbon anode materials with anticipative microstructures for the economical SIBs.