Advanced Li₂ S/Si Full Battery Enabled by TiN Polysulfide Immobilizer

Area of Science:

• Materials Science
• Electrochemistry
• Energy Storage

Background:

• Lithium sulfide (Li₂S) offers high capacity for Li-S batteries but suffers from polysulfide dissolution, leading to rapid capacity degradation.
• Pairing Li₂S cathodes with non-lithium anodes like silicon (Si) can mitigate safety concerns associated with lithium metal anodes.

Purpose of the Study:

• To design a stable and high-performance Li₂S/Si full cell by addressing polysulfide dissolution issues.
• To enhance the cyclability and capacity retention of Li₂S-based batteries.

Main Methods:

• Incorporation of titanium nitride (TiN) as a polysulfide immobilizer within a parallel hollow carbon (PHC) structure for the Li₂S cathode.
• Fabrication and electrochemical testing of the Li₂S/Si full cell, including capacity measurements and cycle stability analysis.
• Utilizing theoretical calculations and experimental diagnostics to confirm polysulfide adsorption and cell performance.

Main Results:

• The Li₂S/Si full cell achieved a high initial reversible capacity of 702 mAh g_Li2S^-1 (1007 mAh g_sulfur^-1) at 0.5 C.
• Demonstrated excellent cyclability with a low capacity fade rate of only 0.4% per cycle over 200 cycles.
• Confirmed strong polysulfide adsorption on TiN and efficient electron/ion transport via the PHC architecture.

Conclusions:

• The TiN polysulfide immobilizer and PHC structure effectively enhance the stability and performance of Li₂S/Si full cells.
• This approach offers a viable strategy for developing highly efficient and long-lasting Li-S batteries.
• The study highlights the potential of flexible Li₂S cathodes and Si anodes for advanced energy storage applications.