Low-Surface-Area Hard Carbon Anode for Na-Ion Batteries via Graphene Oxide as a Dehydration Agent

Abstract

Na-ion batteries are emerging as one of the most promising energy storage technologies, particularly for grid-level applications. Among anode candidate materials, hard carbon is very attractive due to its high capacity and low cost. However, hard carbon anodes often suffer a low first-cycle Coulombic efficiency and fast capacity fading. In this study, we discover that doping graphene oxide into sucrose, the precursor for hard carbon, can effectively reduce the specific surface area of hard carbon to as low as 5.4 m(2)/g. We further reveal that such doping can effectively prevent foaming during caramelization of sucrose and extend the pyrolysis burnoff of sucrose caramel over a wider temperature range. The obtained low-surface-area hard carbon greatly improves the first-cycle Coulombic efficiency from 74% to 83% and delivers a very stable cyclic life with 95% of capacity retention after 200 cycles.

Sulfur‐Doped Carbon with Enlarged Interlayer Distance as a High‐Performance Anode Material for Sodium‐Ion Batteries

“…Different from the reported typical two‐region discharge curves for hard carbons, which showed both sloping region (2.0–0.15 V) of the intercalated Na + ions and plateau region (≈0.1 V) of the absorbed Na + ions,13, 27 the SC only shows sloping region in the discharge curves ( Figure 4 a), indicating that most of the capacity for SC is contributed by the insertion of Na + ions into the parallel or nearly parallel carbon layers. The unconspicuous sloping plateaus centered at ≈1.3 V in the discharge and ≈1.7 V in the charge (Figure 4a) can be addressed by the pseudocapacitance and/or the chemisorption of Na + ions caused by the sulfur functional groups in SC, which may also contribute to the capacity.…”

Review—Hard Carbon Negative Electrode Materials for Sodium-Ion Batteries

“…32 Interestingly, the specific surface area can also be tuned by pre-treatments of the precursor 27,[33][34][35] or post pyrolysis treatment. 30 When the pyrolysis takes place under gas flow (typically Ar), the flow rate has also been found to have an effect in the specific surface area.…”

A review of carbon materials and their composites with alloy metals for sodium ion battery anodes

“…The most widely used carbon material for SIBs anode is hard carbon [79][80][81][82][83][84]. At first, the electrochemical reactions of hard carbon were compared in LIBs and SIBs.…”