Nano‐confined Mo₂C Particles Embedded in a Porous Carbon Matrix: A Promising Anode for Ultra‐stable Na Storage

Abstract

Transition‐metal carbides (TMCs) are emerging as promising electrode materials for electrochemical energy storage devices, owing to their good conductivity and stability. Herein, Mo2C nanoparticles have been successfully encapsulated into a porous N‐doped carbon matrix through in situ confined carbonization. When evaluated as an anode material for sodium‐ion batteries (SIBs), the resultant Mo2C/N‐doped composite (Mo2C‐NC) exhibited a high rate capability and excellent cycle stability with a high capacity retention of 95.4 % after 2500 cycles. The prominent sodium storage performances can be attributed to its special nanoarchitecture, which provides a synergistic effect to offer shortened Na+/e− transfer pathways, highly effective restraint through particle agglomeration, and a buffer for the drastic volume change during the prolonged cycles. Owing to the efficient one‐pot procedure and high electrochemical performances, the porous Mo2C/N‐doped carbon hybrids are great potential anode materials for rechargeable SIBs.

Molybdenum‐based materials for sodium‐ion batteries

“…The theoretical capacity of monolayer Mo 2 C is 132 mAh g −1 , and the average open‐circuit voltage is 0.166 eV. These results have then been experimentally confirmed 94,95 . Mo 2 C might not be appealing for high‐energy applications owing to its relatively small capacity but can be used for high‐power utilization, particularly in a hybrid system.…”

“…Mo 2 C might not be appealing for high‐energy applications owing to its relatively small capacity but can be used for high‐power utilization, particularly in a hybrid system. For example, Mo 2 C/N‐C demonstrated a stable capacity of 204 mAh g −1 upon 200 cycles at 100 mA g −1 95 …”

Micronano Porous Mo2C@C Nanorods Composites as Robust Anodes for Li‐ion Battery

“…Again, as shown in Figure b–d, the electrochemical reaction between Mo 2 C and Li ions still brings no obvious lattice distortion and the corresponding polycrystallinity can be well maintained even after 50 and 100 long cycles, which has been clearly verified from the earlier ex situ XRD results shown in Figure . Thus, the whole specific capacity of the MCC‐T NR composite anodes may majorly come from the following: 1) the Li ions reversibly intercalate/deintercalate from the 2D layered Mo 2 C material, which is also similar to the Na‐ion storage mechanism in Mo 2 C and 2) the enlarged surface area with a micro/nanoporous structure provides more active sites for interfacial Li‐ion facile storage . Moreover, as shown in Figure S10, Supporting Information, the improved electronic conductivity of the optimized MCC‐T NR composite anodes can also be revealed from the electrochemical impedance spectroscopy (EIS) measurement.…”

Carbon Encapsulated and rGO Wrapped Mo2C: an Anode Material with Enhanced Sodium Storage Capacity

“…Therefore, improvement in design of Mo 2 C nanostructure is essential to enhance their electrochemical performance. So far mostly this material has been mostly used as anode material for lithium‐ion battery with capacity around 600–900 mAh g −1 [24–30] . There are very few experimental works reported on Mo 2 C as anode material for sodium ion battery.…”

“…Among all the TMCs, molybdenum carbides have attracted battery researchers due to its excellent metallic conductivity (∼1.02×10 2 S cm −1 ) as it provides faster electron transfer, high thermal conductivity (48.4 Wm −1 K −1 ) as it quickly dissipates the thermal energy during charging‐discharging and high capacity [19–24] . It has been observed that bulk molybdenum carbides cannot completely deliver their theoretical capacities, and on the other hand nanosized carbide materials during annealing are prone to aggregate [24–25] . Therefore, improvement in design of Mo 2 C nanostructure is essential to enhance their electrochemical performance.…”