Liquid Metal as a Self-Healing and Polysulfide Trapping Binder for Lithium Sulfur Battery

Abstract

Lithium sulfur battery (LSB) is one of the promising candidates as next generation energy storage technology due to its high energy density, low cost and environmental friendliness surpassing that of current lithium ion batteries (LIBS). However, LSBs still have some issues that need to be overcome before they can be used commercially. The major obstacle that limits their performance is the dissolution of long-chain lithium polysulfides into the electrolyte which leads to the loss of active material and the capacity decay during the charge/discharge cycles. In this work, we developed an innovative cathode design for LSB by mixing liquid metal (LM) nanoparticles with sulfur and a carbon cloth as a current collector. Because of its liquid nature, LM provides a strong encapsulation of the sulfur particles and prevents the detachment from the current collector albeit the large volume changes and cracking of the sulfur during lithiation and delithiation. Here, electrically conductive LM maintains an electron conduction path and mitigates the loss of active materials. In addition, it acts as a lithium polysulfide entrapment to prevent the shuttle effect and improves the Coulombic efficiency and extends the cycle lifetime. This combination of LM nanoparticles and carbon cloth results in good electrochemical performance and excellent capacity retention by providing high surface area, flexibility, ability to accommodate volume changes, and high electrical conductivity. Our results demonstrate an opportunity of the novel LSB electrode composite using multi-functional LM binder to improve the LSB performance and set a new direction towards the implementation to practical applications.