Bimetallic sulfides regulate the balance of adsorption and dissociation for polysulfides

Regulating the adsorption and dissociation equilibrium of electrocatalytic materials towards lithium polysulfides (LiPS) is a crucial yet challenging step in achieving efficient conversion and utilization of LiPS. To address this, we employed theoretical calculations and designed a carbon hollow cage (CHC) structure embedded with nano-heterostructure particles of Co₉S₈/Ni₃S₄, leveraging the dual interaction of strong adsorption from Co₉S₈ and high catalysis from Ni₃S₄. Theoretical simulations demonstrated that Co₉S₈, acting as an electron acceptor, forms a built-in electric field with Ni₃S₄, enhancing intrinsic conductivity and optimizing electron cloud structure. The Co₉S₈/Ni₃S₄ heterostructure regulated the adsorption and dissociation capabilities of LiPS, lowering Gibbs free energy. Simultaneously, three-dimensional computed tomography (3D-CT) found that the skeleton of the electrode sheet was stable before and after cycling and effectively alleviated the sulfur volume change. Multiple in-situ characterization techniques validated the in-situ phase transformation of sulfur-active materials, confirming the outstanding reversibility of the Co₉S₈/Ni₃S₄@CHC/S cathode. Especially under the high current of 5C, the capacity decay rate is only 0.021 % after 400 cycles. These findings indicate that the nano-heterostructure regulates the balance of adsorption and dissociation of LiPS, offering new insights into the control and mechanism of nano-heterostructure electronic structures.