Understanding Ion Transport Restrictions in Battery Materials

Energy is the driving force behind many aspects of our lives. Recently, there has been a growing demand for energy sources that can provide sufficient power for consumption while also being environmentally friendly. Li-ion batteries, as one type of the renewable energies, have attracted significant research interest. The demand for Li-ion batteries has surged due to increased consumption in electronics, electric vehicles, and power grids. Lithium, as the primary element in Li-ion batteries, is the limiting factor in energy supply. To meet this rising energy demand, researchers are working to increase energy supply from two perspectives. First, countries are ramping up mining efforts for the limited lithium resources available on Earth. However, current state-of-the-art lithium extraction technologies are both energy-intensive and costly to scale up. There is a pressing need for environmentally and economically friendly lithium extraction techniques. Second, researchers are exploring battery electrode materials with high energy density.

In the first part of this thesis work, we investigated the restrictions on Li+ transport in aqueous solutions. First, we developed a redox chemistry to drive Li+ transport from aqueous solutions into solid battery materials. Second, we studied the transport restrictions of redox-mediated Li+ extraction, focusing on bulk solution compositions, redox chemistry, and solid-liquid interfaces. This innovation in redox-mediated Li+ extraction from aqueous solutions reduces chemical costs and minimizes chemical waste produced during Li+ extraction.

In the second part of this thesis work, we studied Li+ transport in thick solid battery electrodes. The current solution to boost energy supply is by integrating individual batteries into battery stacks. However, battery packs occupy a large space, reducing the volumetric energy density of the battery. We investigated Li+ transport in battery materials with high volumetric density, tellurium. Specifically, we studied the influence of material surface area and electrode structure on Li+ transport.