CoSe Nanoparticle Embedded B,N-Codoped Carbon Nanotube Array as a Dual-Functional Host for a High-Performance Li-S Full Battery.

The lithium polysulfide (LiPSs) shuttling and slow chemical reactions at the sulfur cathode and the formation of dendritic lithium in metal anodes severely hinder the popularization of lithium-sulfur batteries. Here, a B,N-codoped carbon nanotube (BNCNTs) array decorated with sulfilic and lithiophilic CoSe nanoparticles grown on a carbon cloth (CoSe@BNCNTs/CC) as both a sulfur and a lithium host is reported. Density functional theory (DFT) calculations, simulations, and electrochemical performance determinations demonstrate that CoSe@BNCNTs/CC can simultaneously exert catalytic effects for accelerating LiPSs conversion and realize smooth and uniform lithium deposition to regulate the S and Li electrochemistry. Moreover, the unique structure of the BNCNTs array provides sufficient storage space for sulfur and homogenizes the distribution of Li ions and the electric field of the electrode. The assembled Li-S full battery with a CoSe@BNCNTs/CC dual-functional host exhibits a long-term cycling stability (800 cycles at 0.5 C with a decay rate of 0.066% per cycle) and a high rate capacity (684 mAh g at 2 C). Even at a high sulfur loading of 7.9 mg cm, the Li-S full battery has a high areal capacity of 9.76 mAh cm at 0.2 C. This study proposes a viable strategy to solve the challenges of both S and Li electrodes for practical Li-S full batteries.