Nickel-Halide Sulfide Solid Electrolyte for Wide-Range Ion Conductivity
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Solution Overview
Problem
Sulfide-based solid electrolytes in existing technologies exhibit high ion conductivity only within specific temperature ranges, limiting their application and safety in lithium secondary batteries.
Innovation Solution
A sulfide-based solid electrolyte composition containing nickel sulfide (Ni3S2) and lithium halide (LiX) with lithium sulfide (Li2S) and diphosphorus pentasulfide (P2S5), which forms a cubic crystal structure through milling and heat-treating, enabling high ion conductivity across a wide temperature range of 200° C. to 600° C.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If conventional sulfide-based solid electrolytes are used, then high ion conductivity is achieved at specific temperatures (200-300°C or 500°C), but the electrolyte fails to maintain high ion conductivity across a wide temperature range
Solution Approach 1:
The patent employs composite materials by combining multiple sulfide-based components (Li2S, P2S5, Ni3S2, Li3PO4, and halogen compounds) to create a composite solid electrolyte. This composite structure enables the material to maintain high ion conductivity across a wide temperature range (200-600°C) by leveraging the complementary properties of each component, resolving the contradiction between achieving high conductivity and broad temperature adaptability.
Solution Approach 2:
The patent applies parameter changes by systematically varying the composition ratios of Li2S, P2S5, Ni3S2, Li3PO4, and halogen compounds in the solid electrolyte. By optimizing these compositional parameters, the electrolyte achieves high ion conductivity across a wide temperature range, transforming the material's properties to meet both conductivity and temperature range requirements simultaneously.
2Reliability
If amorphous solid electrolytes are heat-treated at low temperatures (200-300°C), then high ion conductivity is achieved, but the electrolyte loses its high conductivity properties at higher temperatures
Solution Approach 1:
The patent utilizes phase transitions by controlling the crystallization behavior of the solid electrolyte through heat treatment. The specific composition enables the material to undergo controlled phase transitions that maintain high ion conductivity across a wide temperature range, preventing the loss of conductivity properties at elevated temperatures while still achieving high conductivity through heat treatment.
Solution Approach 2:
The composite structure comprising Li2S, P2S5, Ni3S2, Li3PO4, and halogen compounds creates a synergistic effect where each component contributes to maintaining structural stability and ion conductivity at different temperatures, resolving the issue of conductivity loss at higher temperatures.
3Reliability
If crystalline solid electrolytes are heat-treated at high temperatures (500°C), then high ion conductivity is achieved, but the electrolyte exhibits lower conductivity at lower temperatures
Solution Approach 1:
The patent optimizes compositional parameters including the ratios of Li2S, P2S5, Ni3S2, Li3PO4, and halogen compounds to enable the crystalline solid electrolyte to achieve high ion conductivity at high temperatures while maintaining adequate conductivity at lower temperatures, expanding the operational temperature range.
Solution Approach 2:
The controlled phase transitions in the composite material allow the electrolyte to maintain high ion conductivity across a wide temperature range by leveraging the thermal stability and ionic conductivity characteristics of each component during heating and cooling cycles.
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 sulfide-based solid electrolyte achieves high ion conductivity and stability across a broad temperature range, enhancing battery performance and safety, and facilitating its commercialization by accommodating various manufacturing processes.
Implementation Method 1
The sulfide-based solid electrolyte has high lithium-ionic conductivity compared to the oxide-based solid electrolyte
Implementation Method 2
the amorphous solid electrolyte has ion conductivity at 1×10−3 S/cm at the time of heat-treating (crystallizing) at a relatively low temperature of 200° C. to 300° C.
Implementation Method 3
the crystalline solid electrolyte has ion conductivity at 1×10−3 S/cm at the time of heat-treating (crystallizing) at a temperature of about 500° C.
Data Source
AI summary
A sulfide-based solid electrolyte contains a nickel (Ni) element and a halogen element. For example, a sulfide-based solid electrolyte can include, with respect to 100 parts by mole of a mixture of lithium sulfide (Li2S) and diphosphorus pentasulfide (P2S5), 5 parts by mole to 20 parts by mole of nickel sulfide (Ni3S2), and 5 parts by mole to 40 parts by mole of lithium halide.