Hollow carbon nanospheres with optimized nitrogen configuration controlled by heteroatom doping for high-performance potassium-ion storage

Abstract

As is known, the electrochemical energy storage capability of carbon-based material significantly depends on its intrinsic nitrogen configuration. In this work, the nitrogen configuration in hollow carbon skeleton was controlled by heteroatom phosphorus doping, realized in successfully synthesized N–P co-doping hollow carbon nanospheres (HCNS-NP) samples. When used in K-ion battery, the prepared HCNS-NP electrode retains a discharge capacity of ∼338.8 mA h g−1 at a current density of 100 mA g−1. Furthermore, it achieves a reversible capacity of 180.6 mA h g−1 at a high current density of 1000 mA g−1, even after 1000 cycles. Both experimental and DFT results support that phosphorus doping promote the formation of pyrrole-N within the samples, instead of pyridine-N or graphite-N, which accounts for the enhancement in K-ion conductance and eventually K-ion storage performance. The research opens up a new platform in modifying nitrogen configurations in disordered carbon materials, which should be attractive to the electrochemical, catalysis and material communities.