Highly Reversible Sodium‐ion Storage in A Bifunctional Nanoreactor Based on Single‐atom Mn Supported on N‐doped Carbon over MoS2 Nanosheets

Abstract Conversion‐type electrode materials have gained massive research attention in sodium‐ion batteries (SIBs), but their limited reversibility hampers practical use. Herein, we report a bifunctional nanoreactor to boost highly reversible sodium‐ion storage, wherein a record‐high reversible degree of 85.65 % is achieved for MoS 2 anodes. Composed of nitrogen‐doped carbon‐supported single atom Mn (NC‐SAMn), this bifunctional nanoreactor concurrently confines active materials spatially and catalyzes reaction kinetics. In situ/ex situ characterizations including spectroscopy, microscopy, and electrochemistry, combined with theoretical simulations containing density functional theory and molecular dynamics, confirm that the NC‐SAMn nanoreactors facilitate the electron/ion transfer, promote the distribution and interconnection of discharging products (Na 2 S/Mo), and reduce the Na 2 S decomposition barrier. As a result, the nanoreactor‐promoted MoS 2 anodes exhibit ultra‐stable cycling with a capacity retention of 99.86 % after 200 cycles in the full cell. This work demonstrates the superiority of bifunctional nanoreactors with two‐dimensional confined and catalytic effects, providing a feasible approach to improve the reversibility for a wide range of conversion‐type electrode materials, thereby enhancing the application potential for long‐cycled SIBs.