Dual Solid Electrolyte Structure for High-Rate All-Solid Batteries
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Solution Overview
Problem
All-solid secondary batteries with sulfide-based solid electrolytes face challenges of low reversible capacity at high rates and frequent short circuits due to high interface resistance between the anode and solid electrolyte layers.
Innovation Solution
The implementation of a dual solid electrolyte layer structure, where a first solid electrolyte layer with higher lithium ion conductivity is placed closer to the anode and a second solid electrolyte layer with lower conductivity but better mechanical stability is placed closer to the cathode, both having an argyrodite crystal structure, to reduce interface resistance and enhance lithium ion mobility.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a single-layer solid electrolyte structure is used, then the device complexity is reduced, but the lithium ion conductivity at the anode interface is insufficient leading to high interface resistance
Solution Approach 1:
The solid electrolyte layer is divided into two distinct layers: a first solid electrolyte layer with higher lithium ion conductivity positioned adjacent to the anode, and a second solid electrolyte layer with lower conductivity positioned adjacent to the cathode. This segmentation allows each layer to perform its specialized function, resolving the contradiction between achieving high interface conductivity and maintaining structural simplicity.
Solution Approach 2:
Different regions of the solid electrolyte layer are assigned different material properties. The first layer near the anode uses material with superior lithium ion conductivity to reduce interface resistance, while the second layer near the cathode uses material with appropriate conductivity. This local differentiation of material quality optimizes performance at each interface without requiring complex overall structure.
2Productivity
If a dual solid electrolyte layer structure is implemented, then the lithium ion mobility and reversible capacity are improved, but the device complexity increases
Solution Approach 1:
The solid electrolyte is segmented into two functional layers with different conductivity characteristics. The first layer optimized for high lithium ion mobility enables fast charge/discharge rates, while the second layer provides structural support. This segmentation achieves high productivity without requiring complex external systems or mechanisms.
Solution Approach 2:
The solid electrolyte layer employs a composite structure combining two different sulfide-based solid electrolyte materials. This composite approach allows the system to simultaneously achieve high lithium ion mobility for fast charging and mechanical stability, resolving the contradiction between productivity enhancement and structural complexity.
3Reliability
If the solid electrolyte has high lithium ion conductivity, then the reversible capacity increases, but the mechanical stability may be compromised
Solution Approach 1:
The solid electrolyte layer is segmented into a first layer with high lithium ion conductivity adjacent to the anode for maximizing reversible capacity, and a second layer with appropriate mechanical properties adjacent to the cathode for providing structural stability. This segmentation resolves the contradiction between achieving high reversible capacity and maintaining mechanical strength.
Solution Approach 2:
Different regions of the solid electrolyte structure are assigned different material qualities: the first layer near the anode prioritizes high lithium ion conductivity to enable high reversible capacity, while the second layer near the cathode prioritizes mechanical stability. This local quality differentiation allows the system to achieve both high performance and structural integrity simultaneously.
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
This configuration improves high-rate charge/discharge characteristics, increases reversible capacity, and reduces short circuit occurrences by optimizing lithium ion transport and mechanical stability.
Implementation Method 1
the first solid electrolyte has a lithium ion conductivity which is greater than a lithium ion conductivity of the second solid electrolyte
Implementation Method 2
both having an argyrodite crystal structure, to reduce interface resistance and enhance lithium ion mobility
Data Source
AI summary
An all-solid secondary battery includes a solid electrolyte layer disposed between an anode layer and a cathode layer, where the solid electrolyte layer contains a first solid electrolyte layer including a first solid electrolyte and a second electrolyte layer including a second solid electrolyte, where the first solid electrolyte is disposed proximate to the anode layer, the second solid electrolyte layer is disposed proximate to the cathode layer, and the first solid electrolyte has a lithium ion conductivity greater than a lithium ion conductivity of the second solid electrolyte, where a difference between the lithium ion conductivity of the first solid electrolyte and the lithium ion conductivity of the second solid electrolyte is equal to or greater than about 2 mS/cm.