The expected steep rise in demand for high-capacity energy storage over the coming years, in efforts to reduce the production of harmful emissions from current carbon-containing fuels, has led to intensive research worldwide for high energy density batteries. Lithium sulphur (Li-S) batteries are a promising alternative to the widely employed lithium-ion batteries due to their superior theoretical energy density in addition to low cost and low environmental impact due to sulphur’s high abundancy and low toxicity. Unfortunately, lithium sulphur batteries suffer from sulphur’s low conductivity, large volumetric changes, and the migration of active sulphur away from the cathode that limit their performance and cyclability. This thesis presents investigations into a number of aspects of the lithium sulphur cathode, a key component in combatting these issues. The focus has been put on conductive cathode hosts impregnated with sulphur, and more specifically on cathode host microstructure and functional groups of cathode hosts. A novel lithium sulphur battery continuum model was developed that considers the local pore size distribution and tortuosity and has good predictive ability due to its parameters’ independence from cathode microstructure. The model was successfully validated and used for the assessment of different carbonaceous cathode host microstructures, from activated carbon (AC)-based hosts to graphene and hollow porous particle hosts. Investigations into sulphur melt infiltrated cathodes confirmed the speculated presence of smaller sulphur allotropes other than the dominant S8 allotrope including S6 and S4 that are promoted via micropore restrictions. The fitting of experimental data with the simulation model yielded, for the first time, transferrable reaction kinetics parameter values for lithium sulphur batteries. Investigations into different cathode microstructures provided a comparative assessment and indicated that hollow carbon spheres with porous wall have superior cathode host microstructure over 2D graphene, microporous fibrous hosts and micro-macroporous hierarchical activated carbon. The negative effects of incorporating functional electrocatalyst groups into the hollow porous particle cathode host materials highlighted the importance of their limitation as to not block micro and mesopore openings. The investigations as a whole give direction to future cathode design and fabrication which can be aided by the transferrable simulation model.