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The electrochemical lithium intercalation into natural graphite milled in various atmospheres was investigated. The atmosphere in which the natural graphite was milled has a strong influence on its final morphology and microstructure. These physical properties in turn have a pronounced effect on the electrochemical lithium intercalation process. The lithium storage capacity increases with the amount of disorder present, but it is also associated with a more pronounced discharge and charge potential hysteresis. Although a milled sample with a larger specific surface area is more susceptible to first cycle irreversible reactions, it has a smaller charge-transfer resistance. The chemical diffusion coefficient of intercalated lithium decreases when a large amount of disorder has been introduced into the sample by the mechanical milling process.Carbons are widely used as anode materials in lithium-ion batteries. This is due to their ability to intercalate and deintercalate lithium reversibly at potentials close to that of metallic lithium. However, carbon electrodes suffer complex irreversible reactions 1-3 when they electrochemically intercalate lithium for the first time. These irreversible reactions, involving the electrolyte, solvent, and the carbon electrode, cease when an electronic insulating solid electrolyte interface ͑SEI͒ 4 forms between the carbon electrode and the liquid electrolyte. This phenomenon diminishes the overall specific capacity and energy density of lithium-ion batteries because additional cathode material is required to balance the irreversible reactions. A number of large capacity disordered carbons have been developed in the hope of improving the overall performance of lithium-ion batteries. These large capacity disordered carbons are usually prepared via the pyrolysis of polymeric and organic precursors 5-7 although mechanically milled graphite and soft carbons 8-11 have also been reported to offer large lithium intercalation capacities. However, a better understanding of the lithium intercalation process in these large capacity disordered carbons is needed to optimize their performance.Recently, we have reported that the morphology and microstructure of natural graphite milled in the absence of oxygen evolve very differently from that milled in the presence of oxygen. 12 In this study, the electrochemical lithium intercalation into natural graphite milled in oxygen and nitrogen was investigated. Of particular interest is the effect of the microstructure and morphology of the milled samples resulting from the different milling atmospheres, on the electrochemical lithium intercalation process. ExperimentalThe graphite used was natural graphite ͑230U͒ from Asbury Carbons, Inc., with an average particle size of 15 m. With a ball-topowder weight ratio of 20, 3.52 g of the graphite powder and 20 hardened steel balls ͑9.8 mm in diam͒ were loaded into a hardened steel vial. They were then placed inside a glove bag and purged with nitrogen ͑Ͼ99.9%͒ or oxygen ͑Ͼ99%͒ for 20 min before being sealed. ...

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