A Multifunctional Secondary Based on Heterogeneous Co-MnO@NC for Depth-Induced Deposition and Conversion of Polysulfides in Li─S Batteries.

Abstract

The conductive carbon-based interlayer, as the secondary current collector in the self-dissolving battery system, can effectively capture escaping cathode active materials, inducing deep release of remaining capacity. In the multi-step reactions of Li─S batteries, the environmental tolerance of the conductive carbon-based interlayer to polysulfides determines the inhibition of shuttle effects. Here, a modified metal-organic framework (Mn-ZIF67) is utilized to obtain nitrogen-doped carbon-coated heterogeneous Co-MnO (Co-MnO@NC) with dual catalytic center for the functional interlayer materials. The synergistic coupling mechanism of NC and Co-MnO achieves rapid deposition and conversion of free polysulfide and fragmented active sulfur on the secondary current collector, reducing capacity loss in the cathode. The Li─S battery with Co-MnO@NC/PP separator maintains an initial capacity of 1050mAhg-1 (3C) and excellent cycle stability (0.056% capacity decay rate). Under extreme testing conditions (S load = 5.82mgcm-2, E/S=9.1µLmg-1), a reversible capacity of 501.36mAhg-1 is observed after 200 cycles at 0.2C, showing good further practical reliability. This work demonstrates the advancement application of Co-MnO@NC bimetallic heterojunctions catalysts in the secondary current collector for high-performance Li─S batteries, thereby providing guidance for the development of interlayer in various dissolution systems.