Lithium-Sulfur Batteries: Introduction and Overview Class

Explore the history and resurgence of lithium-sulfur batteries from the 1960s Herbert and Ulam patent to modern solutions addressing the poly sulphide shuttle, with industry investment and carbon-based approaches.

Explore existing sodium-sulfur batteries, using molten sodium and sulfur with a ceramic electrolyte. Learn the discharge/charge mechanism where sodium ions move to sulfur to form polysulfides.

Explore why lithium-sulfur batteries have high energy density yet face key challenges: poor conductivity, shuttle effect, polysulfide dissolution, irreversible capacity, 80% volume expansion, and lithium metal issues.

Investigate the primary issues of lithium-sulfur batteries, including poly sulfide dissolution in electrolyte causing shuttle effects, and the resulting degradation of cathode, anode, and current-collector interfaces.

Overcome sulfur's insulating nature by using a conductive skeleton or carbon encapsulation. Allow electron and lithium ion flow through sulfur-in-carbon structures while mitigating poly sulfide diffusion.

Assess the challenges of sulfur cathode thickness for lithium-sulfur batteries, including mass loading, current collector contact, and polysulfide interactions, and compare to lithium-ion benchmarks.

Explain how the electrolyte dissolves lithium polysulfides, increasing viscosity and reducing lithium-ion mobility, enabling polysulfide diffusion to the anode, precipitating lithium sulfide, and triggering redox chatter that causes self-discharge.

Explore strategies to suppress polysulfide shuttle by encapsulating sulfur and applying coatings, including polymer, graphene, and carbon nanotube structures, to trap sulfur inside and protect electrodes.

Investigate electrolyte strategies for lithium-sulfur batteries, focusing on solvent changes, polysulfide solubility, and the electrochemical stability window. Explore additives, polymer and solid-state options, and key literature.

Explore anode material choices for lithium-sulfur batteries, including lithium metal, protective coatings, and scalable alternatives like carbon-based, silicon, tin, or magnesium-sulfur options, balancing stability, efficiency, and cost.

Identify metrics to commercialize lithium-sulfur batteries, including over 5 mg/cm² phone loading, keep cathode carbon under 5%, limit electrolyte, and ensure a negative-to-positive capacity ratio of at least five.

Explore engineering and mechanical considerations for lithium-sulfur cells, including volume changes, temperature gradients, and thermal management. Address safety factors such as dendrites, separators, electrolytes, and pack design adaptations.