Gradient Supramolecular Preorganization Endows the Derived N/P Dual-Doped Carbon Nanosheets with Tunable Storage Performance toward Sodium-Ion Batteries

Carbon materials with the merits of superior conductivity and wide available resources have emerged as promising anode candidates for sodium-ion batteries (SIBs). However, the inferior capacitance and the limited interlayer spacing restrain their practical application. Herein, we report an atom-adjustable doping strategy to fabricate the N/P dual-doped porous carbon nanosheet anodes (NP-PCN) via the in situ pyrolysis of supermolecules. Nitrogen atoms and phosphorus atoms are introduced to the skeleton with the monomers assembled incrementally. Benefiting from its monomer processability, the supermolecules demonstrate a rationally designed topological structure, endowing the derived carbon anode with a homogeneous heteroatom dispersion with 25.00 at. % of nitrogen and 6.37 at. % of phosphor, an expanded interlayer spacing of 0.47 nm, as well as an optimized configuration of more pyridinic N. Accordingly, the resulting NP-PCN achieves an enhanced reversible capacity of 223 mAh g(-1) at 100 mA g(-1), a robust rate capability of 114 mAh g(-1) at 1000 mA g(-1), and a long cycle life of 4000 cycles with a capacity retention of 92.60%. The storage mechanism is also explored by in situ Raman spectra and galvanostatic intermittent titration technique. This work may inspire new possibility of designing high-performance carbon anodes toward rechargeable alkali-metal-ion batteries at an atomic level.

Automated summary

Carbon materials are considered promising anode candidates for sodium-ion batteries (SIBs) due to their high conductivity and wide availability. However, their practical application is limited by their lower capacitance and restricted interlayer spacing. In this study, an atom-adjustable doping strategy was used to fabricate N/P dual-doped porous carbon nanosheet anodes (NP-PCN) via in situ pyrolysis of supermolecules. The resulting NP-PCN exhibited enhanced reversible capacity, robust rate capability, and long cycle life. The study also explored the storage mechanism and may inspire the design of high-performance carbon anodes for rechargeable alkali-metal-ion batteries at an atomic level.