Surface strain-enhanced MoS₂ as a high-performance cathode catalyst for lithium–sulfur batteries

Lithium–sulfur batteries (LSBs) are one of the main candidates for the next generation of energy storage systems. To improve the performance of LSBs, we herein propose the use of strained MoS₂ (s-MoS₂) as a catalytically active sulfur host. The introduction of strain in the MoS₂ surface, which alters its atomic positions and expands the S–Mo–S angle, shifts the d-band center closer to the Fermi level and provides the surface with abundant and highly active catalytic sites; these enhance the catalyst's ability to adsorb lithium polysulfides (LiPS), accelerating its catalytic conversion and promoting lithium-ion transferability. Strain is generated through the synthesis of core–shell nanoparticles, using different metal sulfides as strain-inducing cores. s-MoS₂ nanoparticles are supported on carbon nanofibers (CNF/s-MoS₂), and the resulting electrodes are characterized by capacities of 1290 and 657 ​mAh g⁻¹ ​at 0.2 and 5 ​C, respectively, with a 0.05% capacity decay rate per cycle at 8 ​C during 700 cycles. Overall, this work not only provides an ingenious and effective strategy to regulate LiPS adsorption and conversion through strain engineering, but also indicates a path toward the application of strain engineering in other energy storage and conversion fields.