A Surface Non-Destructive Modification Strategy Addressing Moisture and Oxidation Instabilities of Sulfide...

Area of Science:

• Materials Science
• Electrochemistry
• Battery Technology

Background:

• Sulfide solid electrolytes offer high ionic conductivity for all-solid-state batteries (ASSBs).
• Their practical use is limited by poor oxidative stability and sensitivity to moisture.
• Existing modification methods often require destructive processes.

Purpose of the Study:

• To develop an in situ, non-destructive surface modification strategy for Li$_{6}$PS$_{5}$Cl (LPSC) solid electrolytes.
• To enhance the moisture tolerance and oxidation stability of LPSC.
• To improve the electrochemical performance and cycling stability of ASSBs.

Main Methods:

• Utilized nucleophilic S$^{2-}$ anions on LPSC surface to initiate ring-opening polymerization of ethylene sulfate (DTD).
• Formed a uniform and dense poly(sulfate) (PS) protective layer on LPSC.
• Fabricated ASSBs using modified PS-LPSC electrolyte, a high-nickel cathode (NCM955), and LiIn anode.

Main Results:

• The PS modification layer effectively shielded LPSC from moisture and high-voltage cathodes.
• ASSBs demonstrated high capacities (e.g., 208.1 mA h g$^{-1}$ at 1 C) at room temperature.
• Exceptional long-term cycling stability was achieved, retaining 70.0% capacity after 36,000 cycles at 10 C and 62.4% after 20,000 cycles at elevated temperatures.

Conclusions:

• The proposed in situ polymerization strategy provides an efficient route for surface modification of sulfide solid electrolytes.
• The PS-LPSC electrolyte exhibits significantly enhanced moisture and oxidation stability.
• This method demonstrates great potential for developing practical and durable all-solid-state batteries.