Balancing Polysulfide Distribution in "Anode-Free" Lithium-Sulfide Batteries.

Area of Science:

• Materials Science
• Electrochemistry
• Energy Storage

Background:

• Lithium-sulfide positive electrodes offer higher capacity and sustainability than traditional metal-based options.
• Anode-free battery designs using lithium-sulfide eliminate the need for lithium metal anodes, boosting energy density and simplifying handling.
• Current anode-free lithium-sulfide batteries often use nickel, compromising sustainability; copper is preferred for greener energy storage.

Purpose of the Study:

• To evaluate methods for enabling stable and reversible operation of anode-free lithium-sulfide batteries with copper electrodes.
• To investigate strategies for restricting polysulfide migration, a challenge in lithium-sulfide battery performance.
• To determine the optimal balance of polysulfide distribution for enhanced reversibility and capacity retention in copper-based anode-free systems.

Main Methods:

• Two approaches were tested to restrict polysulfide migration: in-situ polymerization of an electrolyte additive and electrospinning a polymer layer onto copper negative electrodes.
• Electrochemical performance of the developed anode-free cells was evaluated.
• Polysulfide distribution across battery components was quantified to understand its impact on reversibility.

Main Results:

• Both in-situ polymerization and electrospun polymer layers enabled reversible cycling in copper-based anode-free lithium-sulfide batteries.
• The in-situ polymerization method demonstrated superior capacity retention compared to the electrospinning approach.
• Less polysulfide confinement within the positive electrode was found to be beneficial for overall battery reversibility, contrary to initial expectations.

Conclusions:

• Anode-free lithium-sulfide batteries utilizing copper electrodes can achieve reversible operation through strategies that manage polysulfide migration.
• In-situ polymerization of electrolyte additives presents a promising method for enhancing capacity retention in these systems.
• Achieving optimal performance requires balancing reversibility between the positive and negative electrodes, highlighting a nuanced approach to polysulfide management.