With the existing drawbacks of the Li ion batteries (LIBs) in terms of expenditure and safety, there is an increasing research focus on Na ion batteries (NIBs) as a viable replacement especially for large scale grid storage applications. Considering the rather bulky Na ion and the challenges it would pose for efficient reversibility, choice of optimum electrode materials is of significance. Among the various types of materials being considered for applications as the negative electrode, 2-dimensional (2D) transition metal dichalcogenides (TMDs) have elicited interest due to their layered structure and existing in a range of compositions. Among the various TMDs that have been studied, MoS₂ has received the most focus due to its excellent cyclability as well as stability, however, others in the TMD family have not received as much focus.

In this work, we study the sodium recycling properties of exfoliated TMD (MoSe₂, WSe₂ and MoTe₂)- reduced graphene oxide (rGO) composite. Electrochemical analysis was performed by using the TMDs in coin cells with Na foil being the counter electrode in organic electrolyte within a cycling window of 2.25 V – 10 mV. Cell cycling results have indicated that WSe₂ electrode performed the best and provided a reversible capacity more than 250 mAhg^-1 whereas pristine rGO demonstrated only about 80 mAhg^-1.

Also, all the TMD/rGO composite electrodes demonstrated a first cycle efficiency greater than 50 %. Similarly, capacity retention results demonstrate a similar pattern, with WSe₂ exhibiting about 80 % capacity retention followed by MoSe₂ (∼60 %) and MoTe₂ (∼45%). Results in aqueous media exhibit similar trends.

In conclusion, it can be said that different 2D layered TMDs have shown promise for application as negative electrodes in NIBs in organic and aqueous environment. This provides hope in their extensive application as stable, high reversible capacity negative electrode materials in NIBs.