The continuous evolution of energy storage technologies has been driven by the pursuit of high energy density, abundant and recyclable resources, and battery systems that combine safety with long-term stability. From lead-acid, nickel-cadmium/metal hydride, to lithium-ion batteries, electrochemical energy storage has transformed modern society. In recent years, the rapid growth of electric vehicles has further underscored the urgent demand for zero-emission technologies to mitigate climate change. Beyond transportation, emerging applications such as low-altitude flight, aviation, and unmanned delivery systems also require batteries with both high energy density and cost-effectiveness. Against this backdrop, lithium-sulfur (Li-S) batteries have attracted considerable attention due to their exceptionally high theoretical specific capacity and the low cost of sulfur resources. Nevertheless, the Li-S system faces persistent challenges, including the shuttle effect, sluggish reaction kinetics, and lithium dendrite growth. Despite extensive research efforts over the past decade, the commercialization of Li-S batteries will require not only improved electrochemical performance but also reliable solutions to issues of safety, durability, and scalability. This thesis primarily focuses on leveraging the unique structural and catalytic features of MXenes to enhance the electrochemical performance of Li-S batteries while minimizing additional mass. In Chapter 2, we design an ultrathin SnO2 QDs@MXene heterostructure-based interlayer, which fully exploits the laminar configuration of MXene, the strong polysulfide adsorption capability of SnO2, and the efficient catalytic activity arising from the heterojunction, thereby improving sulfur utilization and redox kinetics. In Chapter 3, we address an often-overlooked failure mode in the early stages of Li-S operation, namely overcharging failure. Through failure diagnosis and systematic analysis, we reveal that cathode-triggered dendrite growth can induce short circuits and pose safety risks. Recognizing that the intrinsic safety concerns of Li-metal anodes remain unresolved, Chapter 4 explores a non-lithium-anode Li-S system by employing commercially mature graphite as a substitute for lithium. Although this substitution sacrifices some energy density, it yields markedly enhanced safety, and we successfully demonstrate a full cell with electrolyte compatible sulfur and lithiated graphite electrodes. Finally, in Chapter 5, we address the critical issue of MXene stability and processability by introducing a novel "MXene dough" storage form, which balances oxidation resistance and redispersibility, offering a practical route for large-scale storage, transportation, and processing of MXenes.