As lithium becomes more expensive and less abundant, sodium-ion batteries (SIBs) will likely become an important alternative to lithium-ion batteries (LIBs) for mobile energy storage applications. Disordered graphitic carbon materials are a promising candidate as SIB anodes due to their low working potential and relative safety compared to metallic sodium; secondary modes of ion storage such as capacitive surface adsorption and pore filling can be used to achieve capacities significantly beyond 372 mAh g^-1, the benchmark capacity for graphite in LIBs. In this work, we investigate the sodiation of a novel type of confined hydrogen-type site found in low-temperature pyrolyzed coronene recently shown to accommodate a high capacity of lithium at ~0.5 V vs. Li/Li⁺, even at high charging rates. Lithium- and sodium-ion insertion were measured under galvanostatic and voltammetric conditions for a series of coronene-derived materials pyrolyzed between 800-2200 °C. Preliminary results demonstrating the disruption of lithiation of the hydrogen-type sites upon heat treatment at 2200 °C are shown in Figure 1. The combination of lithium- and sodium-ion storage properties of such materials is crucial for understanding the mechanism of ion storage in confined sites within graphitic carbons with a high content of internal hydrogen.

<b>Figure 1.</b> Cyclic voltammetry of coronene-derived carbon obtained at (a) 800 °C and (b) 2200 C, measured at 0.1 mV/s between 0.01-1.5 V vs. Li/Li<sup>+</sup>. Both measurements were performed in half-cell configuration against Li metal, in 1M LiPF<sub>6</sub> in EC/DMC as the electrolyte.

Figure 1. Cyclic voltammetry of coronene-derived carbon obtained at (a) 800 °C and (b) 2200 C, measured at 0.1 mV/s between 0.01-1.5 V vs. Li/Li⁺. Both measurements were performed in half-cell configuration against Li metal, in 1M LiPF₆ in EC/DMC as the electrolyte.

Devin McGlamery

Appearances