Hard carbon microspheres derived from resorcinol formaldehyde resin as high-performance anode materials for sodium-ion battery

Hard carbon is a good anode material for sodium batteries due to its disordered structures and large interlayer spacing. However, the high cost and low initial Coulomb efficiencies limit its large-scale application. In this study, we introduce a new way to produce the resorcinol formaldehyde resin-derived hard carbon materials by spray drying and carbonization methods. The SEM and XRD indicate that the hard carbon materials have fine spherule shape and larger layer spacing (d(002) = 0.4 nm). With the electrochemical performance test, we confirmed that RFHC-1100 sample exhibited an outstanding reversible specific capacity of 321 mAh/g and high initial Coulomb efficiency of 82% at the current rate of 0.1 C. In addition, the sodium-ion storage mechanism is analyzed through GITT. This work provides a simple and efficient way to convert resorcinol formaldehyde resins into high-capacity hard carbon materials, which opens up new avenues for the preparation of anode materials for sodium-ion batteries.