Design and Characterisation of new Anode Materials for Lithium-Ion Batteries

University dissertation from Uppsala : Acta Universitatis Upsaliensis

Abstract: Reliable ways of storing energy are crucial to support our modern way of life; lithium-ion batteries provide an attractive solution. The constant demand for higher energy density, thinner, lighter and even more mechanically flexible batteries has motivated research into new battery materials. Some of these will be explored in this thesis.The main focus is placed on the development of new anode materials for lithium-ion batteries and the assessment of their electrochemical and structural characteristics. The materials investigated are: natural Swedish graphite, SnB2O4 glass and intermetallics such as: Cu6Sn5, InSb, Cu2Sb, MnSb and Mn2Sb. Their performances are investigated by a combination of electrochemical, in situ X-ray diffraction and Mössbauer spectroscopy techniques, with an emphasis on the structural transformations that occur during lithiation.The intermetallic materials exhibit a lithium insertion/metal extrusion mechanism. The reversibility of these reactions is facilitated by the strong structural relationships between the parent compounds and their lithiated counterparts. Lithiation of a majority of the intermetallics in this work proceeds via an intermediate ternary phase. The intermetallic electrodes provide high volumetric capacities and operate at slightly higher voltages vs. Li/Li+ than graphite. This latter feature forms the basis for a safer system.Jet-milling of natural Swedish graphite results in decreased particle and crystallite size, leading to improved performance; the capacity is close to the theoretical capacity of graphite. Jet-milled graphite also shows an enhanced ability to withstand high charging rates.

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