g-C₃N₄ templated mesoporous carbon with abundant heteroatoms as high-rate anode material for dual-carbon sodium ion hybrid capacitors

Sodium ion hybrid capacitors (SIHCs) are regarded as advanced power supply systems. Nevertheless, the kinetics imbalance of cathode and anode suppresses the further performance improvement of SIHCs. The carbonaceous anode materials are promising and many strategies have been utilized to increase the capacity of sloping region or accelerate the reaction rate of plateau region. However, it is still challenging to simultaneously realize high mesopore/micropore volume ratio, large interlayer distance (> 0.37 nm), and abundant and favorable heteroatoms-doping by a simple method. Herein, we report N, P, O ternary-doped mesoporous carbon (PNPOC-T, T = 700, 800 or 900) with large interlayer distance (~0.4 nm) as anode materials. The PNPOC-T were prepared by a simple in-situ polymerization of aniline and phytic acid on the exfoliated graphitic nitrogen carbide (g-C₃N₄) and subsequent carbonization. The obtained PNPOC-800 exhibits an excellent rate performance (101.5 mA·h·g⁻¹ at 20 A·g⁻¹), which can be attributed to the high surface-controlled capacitive behavior ratio and rapid ion diffusion. The optimum SIHCs display a high energy density of 105.48 W·h·kg⁻¹ and a high power density of 13.59 kW·kg⁻¹. Furthermore, the capacitance retention rate of SIHCs can reach 87.43% after 9 000 cycles at 1 A·g⁻¹.