An Aqueous Inorganic Polymer Binder for High Performance Lithium-Sulfur Batteries with Flame-Retardant Properties

Area of Science:

• Materials Science
• Electrochemistry
• Energy Storage

Background:

• Lithium-sulfur (Li-S) batteries offer high energy density but face challenges like polysulfide dissolution and sulfur flammability.
• Current binders often fail to adequately address these issues, limiting Li-S battery performance and safety.

Purpose of the Study:

• To develop a novel multifunctional binder for Li-S batteries.
• To address the challenges of polysulfide shuttling, low sulfur utilization, poor cycle life, and flammability in Li-S systems.

Main Methods:

• An aqueous inorganic polymer, ammonium polyphosphate (APP), was synthesized and utilized as a binder in Li-S cathodes.
• The binding affinity of APP with polysulfides and its effect on ion transfer and flame retardancy were investigated.

Main Results:

• APP effectively suppressed polysulfide dissolution and shuttling due to strong binding affinity.
• The binder facilitated Li-ion transfer, enhancing cathode reaction kinetics.
• APP demonstrated flame retardant properties, reducing cathode flammability.
• The Li-S battery with APP binder achieved a high rate capacity of 520 mAh g⁻¹ at 4 C and excellent cycling stability (∼0.038% capacity decay per cycle at 0.5 C for 400 cycles).

Conclusions:

• Ammonium polyphosphate is a promising multifunctional binder for high-performance and safe Li-S batteries.
• The aqueous nature of APP enhances safety by eliminating toxic organic solvents.
• This strategy offers a viable approach for advancing next-generation high energy density Li-S battery technology.