LITHIUM INSERTION INTO DISORDERED CARBONS PREPARED FROM ORGANIC POLYMERS

Disordered carbon samples were prepared from four organic polymers: po ly[(Z)-1-methoxy-4-phenyl-1-buten-3-yne] [poly(MPBEY)], poly(1,4-diphe nyl-1-buten-3-yne) [poly(DPBEY)], poly[5-(2-pyridyl)-2,4-pentadiyn-1-o l] [poly(PyPDO)], and poly(2,4-hexadiyn-1,6-diol) (PHDO). Electrochemi cal Lithium insertion into these disordered carbons was studied with d ischarge/charge tests, cyclic voltammetry, and Li-7 nuclear magnetic r esonance (NMR) spectroscopy. Ln the potential range of 0.0 to 2.5 V vs . Li/Li+, all carbons showed discharge/charge curves with a hysteresis effect unlike typical curves for standard lithium insertion/removal p rocesses in pyrolyzed carbons. This hysteresis may be caused by the li thium-oxygen bonding of the organolithium complexes. Li-7 NMR spectra showed two kinds of lithium insertion sites in all carbons: a reversib le site from which lithium could be removed in the subsequent charge p rocess and an irreversible site where lithium remains intact. The NMR results suggest that the reversible site lithium has ionic nature in a ll of the fully Li-inserted carbons.