Hybrid Garnet Electrolyte Interface for Stable Lithium-Sulfur Cycling
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Lithium-sulfur batteries face challenges with unstable Li metal cycling and the 'polysulfide shuttle effect' in conventional liquid electrolyte configurations, and incompatibility issues with solid electrolytes, leading to capacity loss and high impedances.
Innovation Solution
A hybrid electrolyte system is developed, comprising a solid-state electrolyte with an acid-treated surface and a liquid electrolyte containing an alkali metal salt and an electron pair donor solvent, such as N,N-dimethylacetamide, to stabilize the interface and improve ionic transport.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Speed
If a liquid electrolyte is used in a conventional Li-S battery, then ionic transport is improved, but the polysulfide shuttle effect occurs leading to capacity loss and high impedance
Solution Approach 1:
The electrolyte is segmented into two distinct parts: a solid electrolyte layer in contact with the lithium anode to prevent polysulfide shuttle and maintain stability, and a liquid electrolyte layer in contact with the sulfur cathode to enable efficient ionic transport and solvate polysulfides. This segmentation allows each electrolyte type to perform its optimal function without the drawbacks of using either alone.
2Productivity
If an electron pair donor solvent is used to increase capacity, then sulfur utilization is improved, but stability with lithium metal is lost leading to quick short circuit
Solution Approach 1:
The solid electrolyte acts as an intermediary barrier between the lithium metal anode and the electron pair donor liquid electrolyte. This intermediate layer prevents direct contact and harmful reactions between lithium and the EPD solvent, while still allowing ionic transport. This enables the use of high-capacity EPD solvents without compromising stability with lithium metal.
3Reliability
If a solid electrolyte is used to prevent polysulfide shuttle, then stability is improved, but contact and ionic transport become sluggish leading to high impedance
Solution Approach 1:
Different regions of the electrolyte system have different properties optimized for their specific functions: the solid electrolyte region provides stability and polysulfide isolation where needed, while the liquid electrolyte region provides high ionic conductivity and good contact where needed. This local optimization of properties resolves the contradiction between stability and ionic transport.
Applied Scientific Principles
This section explains which scientific principles are used to turn an abstract innovation direction into a practical engineering solution.
Function Achieved in This Case
The hybrid electrolyte system achieves a stable interface with low interfacial resistance, enhancing the discharge capacity and cyclability of lithium-sulfur batteries by preventing polysulfide shuttle and improving sulfur utilization.
Implementation Method 1
the first surface is an acid-treated surface
Implementation Method 2
EPDs highly solvate polysulfide species and can deliver 24% more capacity than conventional glyme electrolytes
Implementation Method 3
the solid electrolyte acts as a physical barrier to protect the Li metal and isolate polysulfides to the cathode
Implementation Method 4
the liquid electrolyte comprises an alkali metal salt and a solvent
Data Source
AI summary
A hybrid electrolyte comprises: (i) a first electrolyte having a first surface and an opposed second surface, wherein the first electrolyte comprises a solid state electrolyte material comprising an oxide, wherein the first surface is an acid-treated surface; and (ii) a second electrolyte comprising a liquid electrolyte, wherein the liquid electrolyte comprises an alkali metal salt and a solvent selected from the group consisting of electron pair donor solvents, and solvent mixtures including at least one electron pair donor solvent and at least one glyme solvent. The oxide can be a doped or undoped LLZO electrolyte material, and the acid can be selected from H3PO4 and HCl.