Pre-intercalated Sodium Ions Enhance Sodium Storage of MoS<sub>2</sub> Anode by Mitigating Structural Dissociation.

Cen, Mingjun; Yan, Rui; Luo, Xinyu; Liu, Huibin; Chen, Bin; Zhang, Shuya; Peng, Wenchao; Li, Yang et al. · Nano Lett · 2025

basic_science · Level V

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Abstract

Molybdenum disulfide (MoS<sub>2</sub>) is a promising anode for sodium-ion batteries (SIBs) due to its high theoretical capacity and layered structure. However, a poor reversible conversion reaction and a low initial Coulombic efficiency (ICE) limit its practical application. This study systematically investigated the potential of pre-intercalated sodium ions molybdenum disulfide (Na-MoS<sub>2</sub>) as an anode material for SIBs. Because of the mitigation of MoS<sub>2</sub> structural dissociation and effective replenishment of active sodium ions, Na-MoS<sub>2</sub> delivered an outstanding capacity of 507.7 mAh g<sup>-1</sup> after 2000 cycles at 5 A g<sup>-1</sup>, along with an ICE of 95.30%. Pre-intercalating sodium ions can expand interlayer spacing and modulate electronic structure, allowing Na-MoS<sub>2</sub> to have greater tolerance to the electrochemical intercalation/extraction process. Furthermore, the conversion reaction of Na-MoS<sub>2</sub> has a higher Gibbs free energy, implying its structural dissociation is thermodynamically unfavorable. This work provides a new perspective on the study of transition metal dichalcogenide electrode materials for SIBs.