Carbon Quantum Dots and Their Derivative 3D Porous Carbon Frameworks for Sodium‐Ion Batteries with Ultralong Cycle Life

Abstract

A new methodology for the synthesis of carbon quantum dots (CQDs) for large production is proposed. The as-obtained CQDs can be transformed into 3D porous carbon frameworks exhibiting superb sodium storage properties with ultralong cycle life and ultrahigh rate capability, comparable to state-of-the-art carbon anode materials for sodium-ion batteries.

Sodium‐Ion Batteries: Improving the Rate Capability of 3D Interconnected Carbon Nanofibers Thin Film by Boron, Nitrogen Dual‐Doping

“…The BN‐CNFs show excellent cycle stability, and deliver a reversible charge capacity of 581 mAh g −1 after 120 cycles, corresponding to a capacity decay of 0.57% per cycle. Compare with other carbon‐based materials reported in literature, our sample shows improved reversible capacity, especially at low current density, demonstrating the reversible insertion of Na + into the large interlayer space of carbon 49, 52, 53. In contrast, the CNFs, BN‐CNFs‐1, and BN‐CNFs‐2 electrodes show much lower reversible capacity and cyclability (Figure S4, Supporting Information).…”

Large‐Area Carbon Nanosheets Doped with Phosphorus: A High‐Performance Anode Material for Sodium‐Ion Batteries

“…The broad cathodic peak from 0.1 to 1.0 V, appearing in the first cycle, should be related to the formation of the solid electrolyte interface (SEI) film and the reaction between the Na + and surface functional groups. [[qv: 7b,11a,23]] The bumps at ≈0.6 V during the cathodic process from second to fourth cycle should be ascribed to the reversible sodiation process in the surface functional groups 17. The cathodic peaks situated around 0.01 V is stemming from Na + insertion into carbonaceous materials 4, 7, 17.…”

“…And at 5 A g −1 , the charge capacity increases from 43.3 (1st cycle) to 108.8 mAh g −1 (5000th cycle). Nevertheless, after precycling at low current density of 0.1 A g −1 for five cycles, increasing the current density to 5 A g −1 , a high capacity of 149 mAh g −1 can be achieved after 5000 cycles (Figure 7g), benefiting from the activated process at low current density in the first several cycles 17, 24. Figure 7f shows the rate performance of P‐CNSs electrode, the average specific capacities are 328, 269, 235, 208, 169, 143, 117, and 108 mAh g −1 at current densities of 0.1, 0.2, 0.5, 1, 2.5, 5, 10, and 20 A g −1 , respectively.…”

Coordination of Surface‐Induced Reaction and Intercalation: Toward a High‐Performance Carbon Anode for Sodium‐Ion Batteries

“…During the anodic process, no apparent peak is observed in the initial and subsequent cycles, indicating that extraction of Na ions from PC750 happens in a wide potential range 39. Comparing with PC750, the CV curves for ORC‐3 show two additional redox couples at 1.51/2.17 and 0.79/1.62 V, which can be ascribed to the redox reactions between Na ions and oxygen functional groups 40, 41. The similar reactions between Na ions and S were reported previously in Na–S batteries 42, 43.…”