Yolk-double shells hierarchical N-doped carbon nanosphere as an electrochemical nanoreactor for high performance lithium-sulfur batteries

Abstract

Rechargeable lithium-sulfur (Li–S) batteries are regarded as one of the most promising emerging energy technology due to their high theoretical capacity and energy density. However, the shuttle effect from the weak adsorption, poor diffusion-transfer, and insufficient catalytic site restrains further applications. Herein, the yolk-double shells hierarchical N-doped carbon nanospheres (NCS@C-800) were designed as an electrochemical nanoreactor, the material consists of high-content N-doped core-shell carbon nanospheres and a highly graphitized outer carbon shell, which has a gradient of N content. The unique structure host has many advantages, such as huge internal voids, ordered pore structure, and high electrical conductivity. In addition to the introduction of the N element, which offered a large number of adsorption and catalytic sites. Therefore, the NCS@C-800 effectively addresses the three above primary issues for constructing high performance Li–S. The results show that at 500 cycles at 1 C, the as-prepared material is 649 mAh g−1, while at 1000 cycles at 2 C it is 400 mAh g−1, with ultra-low capacity decays of 0.055% and 0.051% per cycle, respectively. More importantly, with an increase in S loading up to 5.43 mg cm−2, it still maintained excellent cycling stability. This work offered an effective strategy for high-performance Li–S batteries.