Sodium-ion batteries present many advantages over lithium-ion batteries for large-scale, stationary energy storage, including higher abundance, lower cost, and simpler processing procedures of sodium compared to lithium. To date, the low energy density and long-term instability of sodium-ion batteries have prevented them from being commercially viable. One of the main research challenges for sodium-ion batteries is finding high capacity anode materials with good voltage window and cycle life when combined with sodium electrolytes. Early research on sodium-ion battery anodes strived to mimic electrode materials from lithium-ion batteries such as graphitic carbons; other simple structured carbons were then studied including hard carbons, petroleum cokes and carbon black¹. However, these structures do not allow the larger sodium ion to diffuse and intercalate as easily as the smaller lithium ion. Research efforts have since broadened to structured carbons such as pyrolized glucose², carbon microspheres³, silica templated carbon⁴, and others. These structures moderately improve performance but still face limitations including low available surface area, poor cycle performance, and complex fabrication.

We propose the application of metal organic framework-derived carbons (MOFDCs) as a large surface area, highly porous, and electrochemically stable material for the sodium-ion battery anode. MOF material is a tunable sacrificial template that, when carbonized, produces ordered, porous structures highly conducive to diffusion and intercalation of sodium ions. Here, we present two MOF structures that are used as sacrificial templates for carbonization, MOF-5 and ZIF-8. After carbonization, the materials were characterized via scanning electron microscopy (SEM) and energy dispersive X-ray spectroscopy (EDS) (Figure 1) to confirm complete carbonization and structural consistency with the starting MOF material. Open cell charge-discharge tests (Figure 2) were performed using a sodium metal cathode and NaClO₄ electrolyte to provide initial confidence in cycle stability and capacity. This work will present detailed characterization of MOF-5 and ZIF-8-derived carbons as sodium-ion battery anode materials, including charge-discharge measurements, cycle performance testing, rate performance testing, and electrochemical impedance spectroscopy measurements.

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