NiCo2O4@PPy concurrently as cathode host material and interlayer for high-rate and long-cycle lithium sulfur batteries

Abstract

The large-scale practical application of cost-efficient lithium sulfur (Li–S) battery with high energy density is impeded due to the shuttle effect and torpid kinetics of polysulfides. Hence, it is significant for Li–S battery to solve these disadvantages to boost the electrochemical performances and facilitate the popularization in various fields. Herein, we synthesized a conductive NiCo2O4@PPy micro-flower-like material via hydrothermal technique followed by subsequent in-situ vapor phase polymerization, and the material was assembled into Li–S batteries to obtain satisfactory electrochemical performances. Flower-like NiCo2O4 expedites the conversion of polysulfides through both physical adsorption and chemical anchoring. Polypyrrole can efficaciously confine polysulfides shuttling, increase the conductivity and concurrently promote lithium ions diffusion. NiCo2O4@PPy is simultaneously served as the effective cathode material and multi-functional interlayer for anchoring-catalyzing polysulfides, which can exhibit a satisfying initial capacity of 1588 mAh g−1 at 0.1C, and the average coulomb efficiency is 95.2%. The highest discharge specific capacity of 740 mAh g−1 is displayed at 2C and the capacity decay rate is 0.107% per cycle after 400 cycles. NiCo2O4@PPy composite is a favorable sulfur host material intimated by these new results, and it is also a competent candidate of interlayer in high-performance Li–S batteries.