Unraveling the Coupling Effect between Cathode and Anode toward Practical Lithium–Sulfur Batteries

Abstract

The localized reaction heterogeneity of the sulfur cathode and the uneven Li deposition on the Li anode are intractable issues for lithium-sulfur (Li-S) batteries under practical operation. Despite impressive progress in separately optimizing the sulfur cathode or Li anode, a comprehensive understanding of the highly coupled relationship between the cathode and anode is still lacking. In this work, inspired by the Butler-Volmer equation, a binary descriptor (I_BD ) assisting the rational structural design of sulfur cathode by simultaneously considering the mass-transport index (I_mass ) and the charge-transfer index (I_charge ) is identified, and subsequently the relationship between I_BD and the morphological evolution of Li anode is established. Guided by the I_BD , a scalable electrode providing interpenetrated flow channels for efficient mass/charge transfer, full utilization of active sulfur, and mechanically elastic support for aggressive electrochemical reactions under practical conditions is reported. These characteristics induce a homogenous distribution of local current densities and reduced reaction heterogeneity on both sides of the cathode and anode. Impressive energy density of 318 Wh kg^-1 and 473 Wh L^-1 in an Ah-level pouch cell can be achieved by the design concept. This work offers a promising paradigm for unlocking the interaction between cathode and anode and designing high-energy practical Li-S batteries.