Optimizing polysulfides adsorption and conversion via crystal-strain modulation for performance-enhanced Li-S batteries

In the electrochemical conversion process of Li-S batteries, catalyst properties, such as the number of active sites, the intrinsic activity of each site, and the overall efficiency are crucial for the conversion of LiPSs. Regulating the structure-activity of a catalyst is essential for achieving excellent electrocatalytic performance. In this work, we employ a crystal-strain modulation strategy to optimize the activity of Co and O sites in Co3O4, thereby improving their adsorption and catalytic capabilities toward LiPSs. By controlling the crystallite size, different lattice strains can be achieved, which significantly regulate the catalyst coordination environment and electronic band structure. Meanwhile, reducing the degree of lattice strain in CC@Co3O4 nanowires increases the among of accessible active sites for reactants, enhancing the adsorption and intrinsic activity of LiPSs, which promotes electron/ion transport as well as sulfur utilization. In the case of CC@Co3O4, when the compressive strain is applied, the lattice structure experiences a reduction in the distance between adjacent atoms, which results in the reduction of interatomic bond lengths, effectively increasing the electron density of the catalyst. Consequently, the S/CC@Co3O4-based cathode with a small lattice strain (2.12 %), exhibits excellent initial capacity and remarkable cycle performance at high sulfur loading (6.6 mg/cm2) and lean electrolyte (E/S: 4.6 mu L/mg). This study highlights a new strategy to improve the adsorption/catalytic activity of electrocatalysts through crystalstrain modulation, representing a rational design for high performance electrocatalysts in Li-S batteries.