Organic polymer coating induced multiple heteroatom-doped carbon framework confined Co1-xS@NPSC core-shell hexapod for advanced sodium/potassium ion batteries

Synthesis of advanced structure and multiple heteroatom-doped carbon based heterostructure materials are the key to the preparation of high-performance energy storage electrode materials. Herein, the hexapod-shaped Co1-xS@NPSC has been triumphantly prepared using hexapod ZIF-67 as the sacrificial template to prepare Co1-xS inner core and N, P, and S tri-doped carbon (NPSC) as the shell through the carbonization of the organic polymer precursor. When applied as anode for Na+ batteries (SIBs) and K+ batteries (PIBs), Co1-xS@NPSC presents the high reversible specific capability of 747.4 mAh/g at 1.0 A/g after 235 cycles and 387.8 mAh/g at 5.0 A/g after 760 cycles for SIBs, as well as 326.7 mAh/g at 1.0 A/g after 180 cycles for PIBs. The excellent storage capacity and rate capability of Co1-xS@NPSC is ascribed to hexapod structure of ZIF-67 unlike the common dodecahedron, which is constructed with interior porous and exterior framework repository, donating supplemental active sites, and doping of multiple heteroatoms forming organic polymer coating inhibiting the volume expansion and restrains the agglomeration of Co1-xS nanoparticles. This approach has paved a bright avenue to exploit promising anode materials with novel structure and hetero-atom doping for high-performance energy storage devices.