An Electrolyte Engineered Homonuclear Copper Complex as Homogeneous Catalyst for Lithium-Sulfur Batteries

Area of Science:

• Materials Science
• Electrochemistry
• Energy Storage

Background:

• Lithium-sulfur (Li-S) batteries face challenges including polysulfide shuttle, slow sulfur conversion, and lithium dendrites, limiting performance and safety.
• Engineered catalysts offer a promising approach to simultaneously address these issues by controlling sulfur and lithium species evolution.

Purpose of the Study:

• To develop and evaluate a homogeneous catalyst for rationalizing Li-S redox reactions.
• To improve the discharge capacity, cycling lifespan, and safety of Li-S batteries.

Main Methods:

• In situ synthesis of a chlorine bridge-enabled binuclear copper complex (Cu-2-T) as a homogeneous electrolyte catalyst.
• Characterization using synchrotron radiation X-ray 3D nano-computed tomography, small angle neutron scattering, and COMSOL simulations.
• Performance testing of Li-S batteries with varying Cu-2-T concentrations under different C-rates and practical conditions.

Main Results:

• Cu-2-T homogeneously guides Li2S nucleation/decomposition and stabilizes the lithium interface.
• A low concentration (0.25 wt%) of Cu-2-T significantly boosts performance.
• Capacity retention improved from 51.4% to 86.3% at 0.2 C and 77.0% at 1.0 C over 400 cycles.
• Stable cycling achieved in soft-packaged pouch cells with high sulfur loading (6.5 mg cm⁻²).

Conclusions:

• The developed Cu-2-T homogeneous catalyst effectively mitigates key limitations in Li-S batteries.
• This catalyst enables enhanced electrochemical performance and stable operation under practical conditions, paving the way for advanced Li-S battery technology.