Li2xSx+w+5zMyP2z Composite for Lithium Sulfur Battery Stability
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Solution Overview
Problem
Lithium sulfur batteries face issues such as low stability against liquid organic electrolyte solutions, sensitivity to moisture and air, and intrinsically low ionic conductivity, limiting their capacity and performance.
Innovation Solution
Development of ionically conductive compounds with the formula Li2x S x+w+5z M y, where M is selected from specific elements, offering improved stability and conductivity through specific compositions and structures, such as amorphous or crystalline forms, for use in electrochemical cells.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Quantity of substance
If conventional lithium sulfur batteries use known sulfide materials (Li2Sx/P2S5 glasses, Li2Sx/P2S5-derived glass ceramics, Li7P3S11, thio-LISICON, oxysulfide glasses), then high capacity is achieved, but stability against liquid organic electrolyte solutions deteriorates
Solution Approach 1:
The patent employs composite materials by combining lithium sulfide (Li2S) with phosphorus sulfides (P2S5, PS3, or SPS) to create a new compound class Li2xSx+w+5zMyP2z. This composite approach leverages the high lithium content of Li2S for capacity while the phosphorus sulfide matrix provides structural stability and resistance to liquid organic electrolytes, resolving the contradiction between high capacity and electrolyte stability.
Solution Approach 2:
The patent systematically varies compositional parameters (x, w, z, y) within the formula Li2xSx+w+5zMyP2z to optimize performance. By adjusting the ratios of Li2S to phosphorus sulfides and incorporating different metal elements M, the patent tunes both capacity and stability properties, demonstrating parameter changes as a key strategy to resolve the technical contradiction.
2Quantity of substance
If known sulfide materials are used in lithium sulfur batteries, then high capacity is achieved, but sensitivity to moisture and air increases
Solution Approach 1:
The patent creates a composite structure where lithium sulfide is embedded within a phosphorus sulfide matrix containing metal elements. This composite architecture protects the highly reactive lithium sulfide from moisture and air while maintaining its lithium-ion conducting properties, thus achieving high capacity with reduced sensitivity to environmental factors.
Solution Approach 2:
The phosphorus sulfide matrix acts as an intermediary barrier between the lithium sulfide active material and the external environment (moisture and air). This intermediate layer protects the sensitive lithium sulfide from degradation while allowing ionic conduction, resolving the contradiction between high capacity and environmental stability.
3Ease of manufacture
If conventional sulfide materials are used, then battery assembly is simplified, but intrinsically low ionic conductivity limits performance
Solution Approach 1:
The patent optimizes ionic conductivity by systematically adjusting compositional parameters within the Li2xSx+w+5zMyP2z formula. By varying the Li2S content (parameter x), phosphorus sulfide ratio (parameters w and z), and metal element composition (parameter y), the patent achieves high ionic conductivity while maintaining ease of manufacture through conventional solid-state synthesis methods.
Solution Approach 2:
The patent creates local regions of high lithium concentration within the phosphorus sulfide matrix, where lithium-rich domains provide high ionic conductivity pathways. This local optimization of lithium distribution maintains ease of manufacture while dramatically improving bulk ionic conductivity performance.
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 compounds enhance the stability and ionic conductivity of lithium sulfur batteries, preventing chemical reactions and improving capacity, making them suitable for repeated charge/discharge cycles in various applications.
Implementation Method 1
ionically conductive compounds... having an amorphous structure... having a crystalline structure, for instance a cubic crystal structure... average ion conductivity of greater than or equal to 10^-4 S/cm
Data Source
Figure 1A
Figure 1B
Figure 1C
AI summary
Ionically conductive compounds, their use, methods for forming particles comprising said compounds, articles comprising said compounds for use in an electrochemical cell and corresponding electrochemical cells are disclosed.