Deciphering Sodium‐Ion Storage: 2D‐Sulfide versus Oxide Through Experimental and Computational Analyses

• Published in: Small (Weinheim an der Bergstrasse, Germany) Germany), 2024-09, Vol.20 (38), p.e2403321-n/a
• Main Authors: Sengupta, Shilpi, Pramanik, Atin, Oliveira, Caique Campos, Chattopadhyay, Shreyasi, Pieshkov, Tymofii, Autreto, Pedro Alves da Silva, Ajayan, Pulickel M., Kundu, Manab
• Format: Article
• Language: English
• Subjects: 2D materials; Anodes; Batteries; Charge transfer; Chemical reactions; Chemical synthesis; Diffusion barriers; Diffusion rate; Electrical resistivity; Electrochemical analysis; Electrode materials; high‐temperature battery; Ion storage; Materials selection; Redox reactions; Sodium; Sodium-ion batteries; Sodium‐ion battery anode; Structural stability; Sulfurization; Transition metals; Tungsten disulfide; Tungsten oxides; tungsten trioxide; Two dimensional analysis
• ISSN: 1613-6810; 1613-6829; 1613-6829
• DOI: 10.1002/smll.202403321

Transition metal derivatives exhibit high theoretical capacity, making them promising anode materials for sodium‐ion batteries. Sulfides, known for their superior electrical conductivity compared to oxides, enhance charge transfer, leading to improved electrochemical performance. Here, a hierarchical WS2 micro‐flower is synthesized by thermal sulfurization of WO3. Comprising interconnected thin nanosheets, this structure offers increased surface area, facilitating extensive internal surfaces for electrochemical redox reactions. The WS2 micro‐flower demonstrates a specific capacity of ≈334 mAh g−1 at 15 mA g−1, nearly three times higher than its oxide counterpart. Further, it shows very stable performance as a high‐temperature (65 °C) anode with ≈180 mAh g−1 reversible capacity at 100 mA g−1 current rate. Post‐cycling analysis confirms unchanged morphology, highlighting the structural stability and robustness of WS2. DFT calculations show that the electronic bandgap in both WS2 and WO3 increases when going from the bulk to monolayers. Na adsorption calculations show that Na atoms bind strongly in WO3 with a higher energy diffusion barrier when compared to WS2, corroborating the experimental findings. This study presents a significant insight into electrode material selection for sodium‐ion storage applications. 2D metal sulfides and oxides are extensively researched as potential anode materials for sodium‐ion batteries (NIBs). Here, the superior performance of 2D tungsten sulfide (WS2) is investigated compared to 2D tungsten oxide (WO3) as an anode material for sodium‐ion batteries (NIBs). Comprehensive experimental and theoretical analyses is conducted to understand the underlying reasons behind this performance difference.