Crystal transformation engineering for effective polysulfides blocking layer for excellent energy density lithium–sulfur batteries

Abstract

Lithium–sulfur batteries (LSBs) with ultra-high energy density are emerging as the best alternative for next-generation energy storage systems. Nevertheless, polysulfide (LiPS) shuttling induces rapid capacity diminution, and short battery lifespan, which seriously hinders their practical application. Herein, a solvothermal and controlled pyrolysis process was used to synthesize the metal-organic frameworks derived m–/c–ZrO2 heterojunction distributed on nitrogen-doped porous carbon (NC) and uniformly wrapped by graphene sheets. Electrochemical investigation demonstrates that the m–/c–ZrO2/NCG heterostructure modified separator can efficiently impede LiPSs shuttling and regulate the conversion reaction of long-chain LiPSs, which is further confirmed by first-principles theoretical calculations. The as-prepared m–/c–ZrO2/NCG-based LSBs showed remarkable cyclability with a decay rate of 0.023 % per cycle over 1000 cycles at a high rate of 2 C. Importantly, at very high sulfur loading of 6.8 mg cm−2, an excellent reversible specific capacity of 924.1 mAh g−1 at 0.2 C after 100 cycles is achieved, which is expected to obtain high energy performance. This work delivers a promised strategy for the rational design of multifunctional heterostructure for stable and safe LSBs, providing a means of narrowing the gap for the commercialization of high-energy next-generation electrochemical storage devices.