Argyrodite Sulfide Solid Electrolyte for Lower Interface Resistance
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Solution Overview
Problem
Solid-state batteries containing sulfide solid electrolytes face increased reaction resistance between the active material and the electrolyte during charging and discharging, leading to deteriorated battery characteristics.
Innovation Solution
A sulfide solid electrolyte with specific diffraction peaks observed within certain ranges during X-ray diffraction measurement, along with a lithium halide hydrate, is used to reduce reaction resistance and improve battery performance.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Power
If a sulfide solid electrolyte is used in a solid-state battery, then the battery can achieve high voltage and simplified safety devices, but reaction resistance increases during charging and discharging, leading to deteriorated battery characteristics
Solution Approach 1:
The patent changes the chemical composition parameters of the sulfide solid electrolyte by incorporating specific ratios of Li2S, P2S5, and Li3PO4 to create a composite material with optimized ionic conductivity and reduced reaction resistance, resolving the contradiction between maintaining high voltage performance and preventing battery characteristic deterioration
Solution Approach 2:
The patent creates a composite sulfide solid electrolyte material combining multiple compounds (Li2S-P2S5-Li3PO4 system) to achieve synergistic effects that simultaneously enable high voltage operation and maintain stable battery characteristics through reduced reaction resistance at electrode interfaces
2Reliability
If the surface of positive electrode active material is coated with specific compounds to restrain reaction resistance increase, then battery characteristics improve, but manufacturing cost increases due to expensive substances required
Solution Approach 1:
The patent merges the electrolyte material with the protective coating function by incorporating Li3PO4 and P2S5 directly into the sulfide solid electrolyte composition, creating a single integrated material that serves both as ionic conductor and as reaction-resistant interface layer, eliminating the need for separate expensive coating materials
Solution Approach 2:
The patent creates an oxide layer on the sulfide solid electrolyte surface through controlled oxidation that replicates the protective function of expensive coating materials like lithium niobate or lithium titanate, providing similar reaction resistance benefits at lower cost
3Reliability
If an oxide layer is formed on the sulfide solid electrolyte surface to restrain high-resistance section formation, then reaction resistance decreases, but manufacturing complexity increases due to moisture control requirements and additional drying steps
Solution Approach 1:
The patent performs preliminary oxidation of the sulfide solid electrolyte surface during the sintering process itself, creating the protective oxide layer before battery assembly, which eliminates the need for subsequent moisture-controlled oxidation steps and drying operations, thereby simplifying the manufacturing process while maintaining low reaction resistance
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 proposed sulfide solid electrolyte achieves high discharge capacity and favorable discharge rate characteristics in solid-state batteries by minimizing reaction resistance between the electrolyte and the active material.
Implementation Method 1
as the solid-state battery is charged and discharged, reaction resistance between an active material and the sulfide solid electrolyte increases, thus limits transportation of lithium ions
Implementation Method 2
JP 2012-94445A discloses an attempt to restrain formation of a high-resistance section by forming an oxide layer on a surface of a sulfide solid electrolyte material, the oxide layer resulting from oxidation of the sulfide solid electrolyte material itself
Data Source
AI summary
A sulfide solid electrolyte is provided having: diffraction peak A observed within a range of 2θ=20.0° to 24.0°; and diffraction peak B observed within a range of 2θ=24.4° to 26.4°, diffraction peak A and diffraction peak B being observed by performing X-ray diffraction measurement using CuKα1 radiation, and the ratio of IA to IB, IA/IB, being 2.0 or less, wherein IA is an intensity of diffraction peak A and IB is an intensity of diffraction peak B. Preferably, the sulfide solid electrolyte contains elemental lithium, elemental phosphorus, elemental sulfur, and an elemental halogen. It is also preferable that the sulfide solid electrolyte has an argyrodite-type crystal structure. It is also preferable that the sulfide solid electrolyte contains a lithium halide hydrate.