Partially carbonised carbon fibres as improved electrodes for structural battery applications

Abstract Carbon fibres are promising materials for structural battery anodes because they can simultaneously provide mechanical reinforcement and act as the electrochemically active material. Their performance depends strongly on their internal structure, which is influenced by the temperature used during carbonisation. Here, we show that partially carbonised carbon fibres produced at different maximum carbonisation temperatures (800 °C to 1100 °C) display systematic changes in both mechanical and electrochemical behaviour. Mechanical testing shows that increasing the carbonisation temperature leads to higher stiffness and tensile strength. Electrochemical measurements reveal a similar trend, with higher reversible capacity and improved cycling stability at higher temperatures. Thus, results show that the general antagonistic dependence on carbonisation temperature observed for conventional carbon fibres is not found for partially carbonised fibres. The partially carbonised fibres show up to 40 percent better electrochemical performance than conventional intermediate modulus carbon fibres. These results highlight the potential in the use of partially carbonised carbon fibres for next-generation structural battery composites, allowing for an expanded multifunctional design window.