Although the commercialisation of lithium-ion batteries is indisputably successful, their financial and environmental issues have raised wide concerns because the resources of elements on which the current lithium-ion batteries highly depend (e.g., lithium, cobalt, copper, nickel, etc.) are critically restricted and unevenly distributed. Therefore, the development of next-generation energy storage devices is of great necessity. In comparison to lithium, sodium-based energy storage technologies belong to one of the promising alternative technologies for next-generation energy storage devices due to the abundance and wide distribution of sodium resources and many other advantages.
This thesis presents a series of works on the rational design of sustainable carbon materials inspired by the hierarchical building blocks of natural biomass (i.e., glucose, cellulose and lignin) for the applications of the emerging sodium-based energy storage technologies (i.e., sodium-ion batteries, sodium-ion capacitors and sodium-metal batteries). 1) The first project focused on developing glucose-derived hard carbon anodes with a reversible capacity of 347.4 mAh g-1 (30 mA g-1) for sodium-ion storage through hydrothermal pre-treatment and high-temperature carbonisation. 2) The second project focused on developing cellulose-derived carbon materials as electrodes for sodium-ion hybrid capacitors with the energy density of 181 Wh kg−1 at 250 W kg−1. 3) The third project focused on developing lignin-derived carbon skeletons with abundant defects as functional hosts to stabilise the metallic sodium anode, which can retain a high Coulombic efficiency (∼99.9%) after long cycling (>1200 hours).
By correlating their structural features and electrochemical performance, the structures of sustainable carbon materials for sodium-based energy storage were optimised to obtain enhanced performance and improved sustainability. Meanwhile, kinetic analysis, advanced characterisation methods and multi-scale modelling were also employed to elucidate the detailed energy storage mechanisms of different applications, which can also benefit the fundamental understanding of the structure-performance relationship of sustainable carbon materials. After the systematic research in this thesis, the promise of emerging sodium-based energy storage technologies can be further consolidated based on sustainable carbon materials inspired by nature with advanced architectures.