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With an attempt to replace petroleum-derived commercial graphite (CG) with biomass-derived carbon, microcrystalline cellulose (MCC) dissolved in 1-butyl-3-methylimidazolium acetate (BMIMAcO) was facilely carbonized to prepare cellulose-derived carbon under a low-temperature range of 250–1600 °C. TEM and AFM results revealed structural evolution of carbon nanosheets starting from carbon dots. The XRD and Raman results showed that the degree of crystallinity of the MCC-derived carbon was apparently enhanced as the temperature was increased to 93.02% at 1600 °C, while the XPS results revealed that the nitrogen content was greatly reduced with increasing temperature. BMIMAcO not only induced low-temperature graphitization of MCC-derived carbon but also provided nitrogen doping for the carbon. Used as an anode of lithium-ion batteries (LIBs), the carbon synthesized at 750 °C showed the best cyclic stability and reversible capacity (1052.22 mAh g–1 at 0.5 A g–1 after 100 cycles and 1017.46 mAh g–1 at 1 A g–1 after 1000 cycles) compared to other MCC-derived carbon and CG. In addition, the costs of cellulose-derived carbon are much lower than those of the petroleum-derived graphite, showing environmental and economical merits for LIB anode production.

Biomass-derived graphitic carbon is becoming an attractive material for anodes in lithium-ion and sodium-ion batteries (LIBs and SIBs) owing to its sustainability. The graphitization of biochar by heating above 2600°C not only requires high energy consumption but also removes heteroatoms that are conducive to electrochemical energy storage. In this study, graphitic carbon nanosheets with N/P-dual doping are facilely synthesized by one-step carbonization of pine sawdust at 800/1000/1200°C that is priorly dissolved in 1-butyl-3-methyl-imidazolium ([Bmim]H 2 PO 4 ) and used as anodes of LIBs/SIBs, respectively.[Bmim]H 2 PO 4 simultaneously promotes the graphitization and porosities of the biochar as carbonization temperature increases in addition to providing N/Pdual doping. Used as anodes of LIBs, IWC-1200 demonstrates excellent rate performance and cyclic stability, delivering 385 mAh g -1 at 1 Ag -1 throughout 1000 cycles. For sodium storage, IWC-1000 exhibits stable capacities of 217 mAh g -1 at 0.1 A g -1 and 101 mAh g -1 at 1 Ag -1 . The electrochemical performances benefit from the graphitized structure with N/P-dual doping, leading to redox pseudocapacitance for lithium/sodium storage. DFT calculations suggest that pyridinic N strongly attracts both Li and Na while P atoms inside the graphitic structure significantly increase the interlayer spacing.