Tailored multifunctional hybrid cathode substrate configured with carbon nanotube-modified polar Co(PO3)2/CoP nanoparticles embedded nitrogen-doped porous-shell carbon polyhedron for high-performance lithium-sulfur batteries.

Despite the overwhelming advantages of high theoretical specific energy and low-cost, the realistic application of lithium-sulfur batteries is still restricted by the shuttle effect of intermediate polysulfides, low conductivity of sulfur and volume variation during charging and discharging. Tailored sulfur cathode is of significant importance for realizing high-performances. This study reports a carbon nanotube (CNT)-modified polar Co(PO3)2/CoP nanoparticles embedded nitrogen-doped porous-shell carbon polyhedron (CNT/CPO/CPNC-1) as a sulfur host to simultaneously overcome the barriers of lithium-sulfur batteries. The shuttle effect can be significantly restrained by the physical confinement of unique porous structure and the chemical adsorption/catalysis conversion of polar Co(PO3)2/CoP and the heteroatom doping of nitrogen. Meanwhile, the porous-shell carbon with interconnected carbon nanotubes can simultaneously provide a conductive framework, facilitate rapid electrical transport, and enable a large inner space to buffer volume expansion. As a result, CNT/CPO/CPNC-1/S cathode demonstrates an excellent reversible capacity of 1371.3 mAh g-1 at 0.1 C with stable Coulombic efficiency of 98% and an outstanding cycling stability with an ultralow capacity decay rate of 0.048% per cycle (500 cycles at 1.0 C). This work pioneers the employment of Co(PO3)2/CoP/carbon hybrid materials as sulfur host and sheds a new light to explore the high-performance lithium-sulfur batteries.