Tailoring the dual precursors coupled hard carbon by embedding the pitch-derived graphitic domains to achieve high-performance sodium storage

Hard carbon has emerged as the most promising anode material for the commercialization of sodium-ion batteries (SIBs) owing to its cost-effectiveness and remarkable sodium storage capacity. Unfortunately, the commercial application of hard carbon has been impeded by its lower initial Coulombic efficiency (ICE) as well as unsatisfied rate capability. In this study, the pitch-derived graphitic domains have been embedded into the hard carbon derived from the coupled precursor of lignin and phenolic resin to regulate its microstructure. The hard-soft carbon with the optimized structure exhibits the relatively low specific surface area of 5.6 m2 g-1 and large interlayer spacing of 0.376 nm, beneficial for improving the ICE and sodium storage capacity. Embedding plenty of graphitic domains can provide the fast transport channels for Na+ and electron, boosting the rate capability. Consequently, the fabricated hard-soft carbon anode demonstrates higher ICE of 89 % and remarkable cycling stability with the capacity retention of 84 % after 1000 cycles at 1 C. Moreover, even at a higher current density of 6 C, the anode maintains the reversible capacity of 193 mA h g-1. This work proposes an effective strategy for the development of hard carbon anodes with higher ICE and high-rate sodium storage capabilities, making it suitable for practical SIBs.