Li⁺ mobility powered by a crystal compound for fast Li-S chemistry

Area of Science:

• Materials Science
• Electrochemistry
• Energy Storage

Background:

• The shuttle effect of polysulfides hinders lithium-sulfur (Li-S) battery performance.
• Blocking layers can suppress this effect but often impede ionic transport.

Purpose of the Study:

• To develop a material that simultaneously alleviates polysulfide shuttling and facilitates Li+ transport in Li-S batteries.
• To enhance the electrochemical performance and cycle life of Li-S batteries.

Main Methods:

• Synthesized a lithium-based crystal composited with carbon (LiPN₂@C) via one-step annealing of Li+ absorbed melamine polyphosphate.
• Modified a separator with the LiPN₂@C material.
• Investigated the electrochemical performance of Li₂S cathodes with the modified separator.

Main Results:

• The LiPN₂@C material effectively suppressed polysulfide shuttling and improved Li+ transport.
• Li₂S cathodes showed a lower activation potential (2.4 V) and high-rate capacity (519 mA h g⁻¹ at 2C).
• The battery achieved a capacity of 726 mA h g⁻¹ at 0.5C with a low decay rate (0.25% per cycle over 100 cycles).

Conclusions:

• The LiPN₂@C composite is a promising material for enhancing Li-S battery performance.
• Simultaneous suppression of polysulfide shuttling and facilitation of Li+ transport are crucial for advanced Li-S battery design.