Vine Shoots‐Derived Hard Carbons as Anodes for Sodium‐Ion Batteries: Role of Annealing Temperature in Regulating Their Structure and Morphology

Abstract

Sodium‐ion batteries (SIBs) are considered one of the most promising large‐scale and low‐cost energy storage systems due to the abundance and low price of sodium. Herein, hard carbons from a sustainable biomass feedstock (vine shoots) were synthesized via a simple two‐step carbonization process at different highest temperatures to be used as anodes in SIBs. The hard carbon produced at 1200 °C delivered the highest reversible capacity (270 mAh g–1 at 0.03 A g–1, with an acceptable initial coulombic efficiency of 71%) since a suitable balance between the pseudographitic domains growth and the retention of microporosity, defects, and functional groups was achieved. A prominent cycling stability with a capacity retention of 97% over 315 cycles was also attained. Comprehensive characterization unraveled a three‐stage sodium storage mechanism based on adsorption, intercalation, and filling of pores. A remarkable specific capacity underestimation of up to 38% was also found when a two‐electrode half‐cell configuration was employed to measure the rate performance. To avoid this systematic error caused by the counter/reference electrode polarization, we strongly recommend the use of a three‐electrode setup or a full‐cell configuration to correctly evaluate the anode response at moderate and high current rates.

Unraveling the Microcrystalline Carbon Evolution Mechanism of Biomass-Derived Hard Carbon for Sodium-Ion Batteries

“…Sodium-ion batteries (SIBs) are one of the most promising candidates for large-scale energy storage and new energy transportation, attributed to their abundant sodium resources, excellent weather resistance, and safety. − Furthermore, SIBs have similar structural compositions and working principles as lithium-ion batteries (LIBs), and their large-scale production can use the existing production lines of LIBs. Many types of cathode materials for SIBs are already well developed, but high-performance anode materials for SIBs are still lacking.…”