The Effects of Near Surface and Bulk Microstructure on Lithium Intercalation of Disordered, “Hard” Carbons

Disordered carbons were synthesized at 700°C from methacrylonitrile-divinylbenzene precursors. The disorder, even at the free surface, was confirmed with TAM. These powdered carbons were subjected to rapid surface heating by a pulsed infrared laser. While the bulk structure remained essentially unchanged, there was substantial surface reconstruction to a depth of 0.25μm after heating (5.9 W average power at 10Hz, 10 ns pulse width, 1064nm wavelength). The surface ordering appears similar to the bulk microstructure of carbons isothermally annealed at 2,200°C (i.e., turbostratic). Improvements were observed in first cycle irreversible loss, rate capability, and coulombic efficiencies of the reconstructed carbons, relative to the untreated carbon.