Elucidating Ion Transport Phenomena in Sulfide/Polymer Composite Electrolytes for Practical Solid-State Batteries

Area of Science:

• Materials Science
• Electrochemistry
• Solid-State Batteries

Background:

• Inorganic/polymer composite solid-state electrolytes (CSEs) are of significant interest for solid-state batteries (SSBs).
• However, the fundamental ion transport mechanisms within CSEs remain poorly understood.
• Understanding ion conduction at inorganic-polymer interfaces is crucial for advancing SSB technology.

Purpose of the Study:

• To elucidate the mechanistic understanding of bi-percolating ion channel formation in CSEs.
• To investigate ion conduction across inorganic-polymer electrolyte interfaces.
• To develop high-performance CSEs for advanced solid-state batteries.

Main Methods:

• Formulation of a model CSE using argyrodite-type Li6PS5Cl (LPSCl) and a gel polymer electrolyte (GPE) with a Li+-glyme complex.
• Analysis of the influence of GPE elasticity on the LPSCl phase percolation threshold.
• Manipulation of Li+-glyme complex solvation/desolvation to enhance interfacial ion conduction.
• Fabrication and testing of a scalable CSE in an SSB full cell with a high-mass-loading cathode and graphite anode.

Main Results:

• The percolation threshold of LPSCl in the CSE is significantly influenced by the GPE's elasticity.
• Tuning the solvation behavior of the Li+-glyme complex effectively promotes ion conduction across the LPSCl-GPE interface.
• A scalable CSE (8x6 cm, ~40 µm thick) was successfully fabricated.
• The fabricated SSB full cell achieved a high volumetric energy density of 480 Wh Lcell−1 and demonstrated stable cycling at 25 °C.

Conclusions:

• A mechanistic understanding of ion transport in CSEs, particularly at inorganic-polymer interfaces, has been established.
• The developed CSE exhibits superior performance compared to previously reported CSE-based SSBs.
• This research paves the way for the development of next-generation high-energy-density solid-state batteries.