Developing accurate models of energy storage devices allows for the simulation of the processes within the cells without the need for expensive and time-consuming experimental testing. Many models have been developed in the past, however sweeping assumptions are often made with respect to the pore structure. These generally assume a uniform pore size and structure, and do not take into account the effects of different pore sizes present in a true electrode material. Pore network models are able to do this, but require complex or expensive pieces of software and a long simulation time.
In this project, a novel continuum model of mass and charge transport has been developed catering for the many pore sizes in an electrode. This model allowed for the simple implementation of a pore size distribution into the simulation of the processes in several supercapacitor configurations, a lithium-sulphur battery, and two lithium-oxygen battery configurations. This novel approach involved characterising an electrode material through analysis of the pore structure and pore size distribution. A novel mathematical transient volume averaged model was developed to solve for the mass transport of species within pores of different sizes. The use of this model in each case demonstrated good agreement with experimental data and allowed for analysis of the effects of different pore structures on the activity of cells. It was found that larger pores (in the macropore region) facilitate mass transport of species, and smaller pores (in the micropore region) have a reduced rate of mass transport and a higher rate of reaction (in batteries) and stern layer formation (in supercapacitors). This novel model demonstrated the importance of modelling ion transport through multiple pore sizes of an electrode material. This model also addresses the need for more complex energy storage device simulation in a reasonable solving time without the need for expensive pieces of software.