Lithium–Sulfur Cells: The Gap between the State‐of‐the‐Art and the Requirements for High Energy Battery Cells

TLDR

Li–S cells promise high gravimetric energy density, yet the current benchmark is the Panasonic NCR18650B at ≈240 Wh kg⁻¹ with several hundred stable cycles. The long‑term goal of Li–S research is to surpass the performance of state‑of‑the‑art Li‑ion cells. The authors model 18650 Li–S cell energy and cost across sulfur loads, utilizations, and electrolyte/sulfur ratios, then compare the required cell and electrode properties with statistics from 274 recent publications to expose the gap to high‑energy requirements. They present a carbon‑nanotube‑based electrode that satisfies key criteria for achieving high gravimetric cell energy densities.

Abstract

Li–S cells are considered a highly attractive electrochemical storage system, especially due to their high potential gravimetric energy density. The long‐term target of all Li–S research activities must be to outperform state‐of‐the‐art Li‐ion cells. A current benchmark is the Panasonic NCR18650B, which has a gravimetric energy density of ≈240 Wh kg −1 and several hundred relatively stable cycles. The possible 18650 Li–S cell energies and cell costs are calculated for various sulfur loads, sulfur utilizations, and electrolyte/sulfur ratios with the aim of determining the cell and electrode property values required to outperform the NCR18650B. These values are compared with statistical information obtained from an extensive literature review of 274 Li–S publications over the last 12 years to show the gap between state‐of‐the‐art Li–S research and requirements for high energy density cells. Finally, a carbon nanotubes‐based electrode is introduced, which meets important criteria for obtaining high gravimetric cell energy densities.