From Lithium–Sulfur to Lithium–ion: Strategies for Improved Battery Materials

Improved battery materials are necessary to offset the intermittency of renewable energy sources such as wind and solar, to provide enhanced driving range and faster charging speeds for electric vehicles, and to make portable electronics lighter, faster, and longer lasting. There is a range of materials for next-generation batteries that fit can fit each of these needs. Lithium–sulfur (Li–S) batteries are one such technology that has the potential of increasing energy density for portable electronics while using an environmentally-conscious active material, elemental sulfur. All-solid-state batteries are another technology that has potential to increase energy density and also improve upon safety by removing flammable liquid electrolytes from the cell. Next-generation Li-ion batteries employing electrodes with 3-dimensional crystal structures have the opportunity to greatly increase the rate capabilities of batteries, which is especially important for electric vehicle applications.These three next-generation battery technologies will be discussed in the context of detailed structure-property relationships of disulfide polymers as Li–S electrodes, lithium thiophosphate solid electrolytes for all-solid-state batteries, and oxide structures with highly connected metal-oxygen octahedra for fast-charging Li–ion batteries. I use different synthesis techniques including air-free solution synthesis and solid state synthesis to make materials and use a combination of electrochemical measurements, such as galvanostatic cycling, cyclic voltammetry, electrochemical impedance spectroscopy to characterize the electrochemical properties of these materials. I also use a variety of \textit{ex situ} and \textit{operando} techniques, particularly Raman spectroscopy, X-ray photoelectron spectroscopy, XANES, X-ray diffraction, among others, to gain a detailed mechanistic understanding of the underlying chemistry and redox processes that drive the performance of these materials