Engineering the Catalytic Superlattices for Highly Reversible Sodium-Ion Storage with A high Compositional Conversion...

A major obstacle of transition metal disulfides in sodium-ion batteries is compositional irreversible conversion, leading to fast capacity decay. Here, we propose to engineer a catalytic superlattice structure for achieving a record-high compositional reversible conversion degree (≈100 %). The superlattice is constructed by alternately stacking MoS₂ layers and nitrogen/oxygen co-doped reduced graphene oxide-supported single-atom metal layers (MoS₂/M-ONG SL, M=Fe, Co, Ni, Cu, Zn) with 100 % MoS₂/M-ONG interfaces, in which the metal atoms bridge the two layers through S-M-O chemical bonds. Using MoS₂/Co-ONG SL as a model, the unique superlattice structure shows excellent electron and Na⁺ transport properties during discharge and charge. Moreover, the Co-ONG boosts Na₂S adsorption and decomposition by forming Co-3d and S-3p hybridization. As a result, the MoS₂/Co-ONG SL shows a high compositional reversible conversion degree(≈100 %), as proven by a series of in-/ex situ spectroscopic analyses. As a result, the MoS₂/Co-ONG SL exhibits a stable cycling stability of 300.7 mAh g^-1 after 2000 cycles at 2 A g^-1, with an ultrasmall capacity decay rate of 0.41 % per 100 cycles. This work offers a noteworthy perspective on the design and fabrication of conversion-type materials, emphasizing the crucial role of interface engineering in achieving excellent bidirectional reaction kinetics.