Dramatically Accelerated Formation of Graphite Intercalation Compounds Catalyzed by Sodium.

Iyo, Akira; Ogino, Hiraku; Ishida, Shigeyuki; Eisaki, Hiroshi · Adv Mater · 2023

basic_science · Level V

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Abstract

Graphite intercalation compounds (GICs) have a variety of functions due to their rich material variations, and thus, innovative methods for their synthesis are desired for practical applications. It is discovered that Na has a catalytic property that dramatically accelerates the formation of GICs. It is demonstrated that LiC<sub>6</sub> <sub>n</sub> (n = 1, 2), KC<sub>8</sub> , KC<sub>12</sub> <sub>n</sub> (n = 2, 3, 4), and NaC<sub>x</sub> are synthesized simply by mixing alkali metals and graphite powder with Na at room temperature (≈25 °C), and A<sub>E</sub> C<sub>6</sub> (A<sub>E</sub>  = Ca, Sr, Ba) are synthesized by heating Na-added reagents at 250 °C only for a few hours. The NaC<sub>x</sub> , formed by the mixing of C and Na, is understood to act as a reaction intermediate for a catalyst, thereby accelerating the formation of GICs by lowering the activation energy of intercalation. The Na-catalyzed method, which enables the rapid and mass synthesis of homogeneous GIC samples in a significantly simpler manner than conventional methods, is anticipated to stimulate research and development for GIC applications.