Composite Electrolyte for Stable Solid-State Battery Interfaces
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Solution Overview
Problem
All solid Li-ion secondary batteries face challenges in maintaining a stable interface between the solid electrolyte and active material due to expansion and shrinkage during charge and discharge cycles, leading to poor cycle performance, especially at low temperatures.
Innovation Solution
A composite electrolyte comprising an inorganic solid particle mixture with a broad particle size distribution and a nonaqueous electrolyte, where the inorganic solid particles have varying Li-ion conductivities, promoting dielectric polarization and increased Li-ion concentration for improved conductivity and stability.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a solid electrolyte is used in all solid Li-ion secondary batteries, then safety is improved and ignition is reduced, but interface stability deteriorates due to expansion and shrinkage of active material during charge and discharge cycles
Solution Approach 1:
The patent uses a composite electrolyte comprising inorganic solid particles (such as LiNbO3, Li2SiO3, or Li4SiO4) dispersed in an organic electrolyte. This composite structure combines the safety benefits of solid electrolytes with the flexibility and adhesion properties of liquid electrolytes, maintaining stable contact with active materials during expansion and shrinkage while preventing ignition.
Solution Approach 2:
The patent changes the physical state of the electrolyte from purely solid to a composite state with specific particle size distributions (D10, D50, D90 parameters optimized). The inorganic solid particles have controlled size ranges that allow them to fill voids and maintain interface stability, while the organic electrolyte provides flexibility. This parameter optimization resolves the contradiction between safety and interface stability.
2Quantity of substance
If the active material is expanded and shrunk by insertion and extraction of Li, then charge and discharge capacity is improved, but interface adhesion deteriorates causing separation from solid electrolyte
Solution Approach 1:
The inorganic solid particles act as intermediaries between the active material and the organic electrolyte. These particles (LiNbO3, Li2SiO3, Li4SiO4 with optimized size distributions) maintain physical contact and adhesion during volume changes, while allowing Li ion transport. The composite structure mediates the mechanical stress from expansion and shrinkage, preventing separation.
Solution Approach 2:
The composite electrolyte creates a porous-like structure with inorganic particles dispersed in the organic electrolyte matrix. This structure accommodates the volume changes of active materials during Li insertion/extraction, maintaining interface adhesion while allowing continuous electrolyte contact for high charge and discharge capacity.
3Reliability
If inorganic solid particles with broad particle size distribution are used, then Li-ion conduction is improved through dielectric polarization, but manufacturing complexity increases
Solution Approach 1:
The patent optimizes specific particle size parameters (D10, D50, D90) of inorganic solid particles to achieve optimal Li-ion conduction through dielectric polarization effects. The controlled size distribution (with D90/D10 ratio optimized) creates enhanced polarization at particle interfaces, improving Li ion transport. The manufacturing complexity is managed by specifying clear particle size ranges rather than requiring complex multi-stage processing.
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 composite electrolyte enhances Li-ion conduction and cycle performance, reducing the load on battery components and maintaining electrical insulation, thereby achieving excellent life and output performance even at low temperatures.
Implementation Method 1
the inorganic solid particles have varying Li-ion conductivities, promoting dielectric polarization and increased Li-ion concentration for improved conductivity and stability
Data Source
Figure 1
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AI summary
According to one approach, a composite electrolyte (9) is provided. The composite electrolye (9) includes an inorganic solid particle mixture (91) and a nonaqueous electrolyte (92) which includes Li. The inorganic solid particle mixture (91) includes first inorganic solid particles (91A) having a first Li-ion conductivity at 25°C and second inorganic solid particles (91B) having a second Li-ion conductivity at 25°C being lower than that of the first inorganic solid particles (91A). A ratio of a weight of the nonaqueous electrolyte (92) to a weight of the composite electrolyte (9) is from 0.1% to 25%. The inorganic solid particle mixture (91) satisfies 10 ≤ d90/d10 ≤ 500.