In Figure (b), we show that fitting ∆𝜌(𝑟) 𝑠ℎ𝑎𝑟𝑝 to the rexpanded model adequately accounts for the sharp component during the plateau region. In Figure (c), we show that the C-C bond distance increases at the start of the plateau region and remains unchanged during the plateau region, suggesting no further reduction of the carbon during the plateau region. In contrast, as the HCs approach full sodiation, there is significant metallic sodium cluster formation which requires electron transfer to the sodium.