Constructing ultrafine Cu nanoparticles encapsulated by N-doped carbon nanosheets with fast kinetics for high-performance lithium/sodium storage

Carbon-based materials are extensively applied in Li/Na-ion batteries (LIBs/SIBs) anode material. Nevertheless, the poor rate performance, sluggish reaction kinetics, and fast capacity fading during cycling process seriously impedes large-scale commercial application. Herein, ultrafine Cu nanoparticles encapsulated within N-doped carbon nanosheets (labeled Cu/NC) with enlarged interlayer distances, increased intrinsic defects, abundant metallic Cu sites, and hierarchical porous structure were facilely and efficiently fabricated by a room-temperature grinding followed by high temperature pyrolysis. The Cu/NC as electrodes show a high capacity of 788 mAh g(-1) in LIBs, and 434 mA h g(-1) in SIBs at 0.2 A g(-1), as well as good cycling stability with 123 mAh g(-1) for LIBs and 177 mAh g(-1) for SIBs at 10 A g(-1) after 2000 cycles. The as-assembled sodium-ion hybrid capacitors (SIHCs) deliver a high energy/power density of 97 Wh kg(-1) at 181 W kg(-1), remarkable capacity retention of 95.8% after 10,000 cycles and practical applications (69 LEDs can be easily lighted). The experimental results couple with theoretical calculation indicate that the incorporating of Cu and N species can provide abundant active sites and structural defects, resulting in fast reaction kinetics for Li/Na-ion storage.