Carbon fibres (CFs), originally made for use in structural composites, have also been demonstrated as high capacity Li-ion battery negative electrodes. Consequently, CFs can be used as structural electrodes; simultaneously carrying mechanical load and storing electrical energy in multifunctional structural batteries. To date, all CF microstructural designs have been generated to realise a targeted mechanical property, e.g. high strength or stiffness, based on a profound understanding of the relationship between the graphitic microstructure and the mechanical performance. Here we further advance this understanding by linking CF microstructure to the lithium insertion mechanism and the resulting electrochemical capacity. Different PAN-based CFs ranging from intermediate-to high-modulus types with distinct differences in microstructure are characterised in detail by SEM and HR-TEM and electrochemical methods. Furthermore, the mechanism of Li-ion intercalation during charge/discharge is studied by in situ confocal Raman spectroscopy on individual CFs. RamanG band analysis reveals a Li-ion intercalation mechanism in the high-modulus fibre reminiscent of that in crystalline graphite. Also, the combination of a relatively low capacity of the highmodulus CFs (ca. 150 mAh/g) is shown to be due to that the formation of a staged structure is frustrated by an obstructive turbostratic disorder. In contrast, intermediate-modulus CFs, which have significantly higher capacities (ca. 300 mAh/g), have Raman spectra indicating a Li-ion insertion mechanism closer to that of partly disordered carbons. Based on these findings, CFs with improved multifunctional performance can be realized by tailoring the graphitic order and crystallite sizes.

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In order to increase the corrosion resistance and simultaneously maintain the creep resistance of 9-12% Cr steels at 650°C, a new alloy design concept was proposed, using thermodynamically stable Z-phase (CrTaN) precipitates to strengthen the steel. A new trial Zphase strengthened 12% Cr steel was produced and creep tested. The steel exhibited good long-term creep resistance. Dense nano-sized Z-phase precipitates were formed at the early stage, and coarsened slowly. They remained small after more than 10,000 hours.Martensitic 9-12% Cr steels offer an optimal combination of the critical properties, i.e. creep strength, corrosion resistance, thermal conductivity and thermal expansion, at a relatively low cost. Therefore, they are by far the most used material for steam pipes and turbine components in steam power plants [1]. The thermal efficiency of these plants is limited by the maximum allowed steam temperature and pressure, which in turn are determined by the longterm creep and corrosion resistance of economically viable materials. Although austenitic steels have better creep and corrosion resistance, the superior thermal properties of 9-12% Cr steels (high thermal conductivity and low thermal expansion) make them better suited for future power plants. For these plants thermo-flexibility is an essential requirement to accommodate the fluctuating nature of many of the major renewable sources of energy, such as wind and solar power. The cost of 9-12% Cr steels is also substantially lower than austenitic steels, which is of great importance for the economy of introducing improved

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