Core-Shell Sulfur Cathodes for Conductivity and Dissolution Control

The patent employs a core-shell composite structure where sulfur-based active material forms the core and a conductive shell material envelops it. This composite architecture combines the high capacity advantage of sulfur with the electrical conductivity of the shell material, resolving the contradiction between achieving high specific capacity and maintaining adequate electrical conductivity.

The conductive shell in the core-shell composite not only provides electrical conductivity but also facilitates ion transport. The shell material is selected to possess both electronic and ionic conductivity properties, enabling simultaneous improvement in both electrical and ionic conductivity while maintaining the high capacity benefits of sulfur-based cathodes.

The core-shell structure provides structural stabilization where the shell acts as a protective framework that maintains the integrity of the sulfur core during electrochemical cycling. This composite architecture prevents sulfur dissolution and maintains structural stability while preserving the high capacity characteristics of the sulfur-based cathode material.

The conductive shell in the core-shell composite serves as a protective barrier that prevents sulfur dissolution into the electrolyte. This shell encapsulation maintains the sulfur core's structural integrity and prevents loss of active material, thereby preserving the high capacity advantages while eliminating the dissolution problem.

The core-shell composite structure enhances electrochemical reversibility by providing stable interfaces that facilitate reversible lithium insertion and extraction. The conductive shell ensures efficient electron transport during cycling, while the protected sulfur core maintains its capacity for reversible reactions, thereby improving overall electrochemical reversibility while preserving high capacity.