All-solid-state battery with high-melting additive particles
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Solution Overview
Problem
All-solid-state batteries experience internal short-circuiting due to contact between the positive and negative electrode active material layers caused by softening and collapse of the solid electrolyte layer during improper use, such as overheating.
Innovation Solution
Incorporating additive particles with a melting point of 700°C or higher and a median diameter ratio of 0.4 to 0.8 within the solid electrolyte layer to prevent contact between the electrode layers, using metal oxide particles like Al2O3 or SiO2, and maintaining a content of 3% to 10% by weight to inhibit short-circuiting while maintaining lithium ion conductivity.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Quantity of substance
If the solid electrolyte layer is made thinner to improve battery density, then energy density is improved, but the layer becomes more susceptible to softening and collapse during improper use
Solution Approach 1:
The solid electrolyte layer is formulated as a composite material containing solid electrolyte particles (e.g., sulfide solid electrolyte) and additive particles (e.g., metal oxide particles like Al2O3 or SiO2). This composite structure provides both the necessary ion conductivity from the solid electrolyte particles and the high-temperature structural stability from the additive particles with melting points of 700°C or higher, resolving the contradiction between thinning the layer for density and maintaining reliability during thermal abuse.
Solution Approach 2:
The invention changes the physical and chemical parameters of the solid electrolyte layer by controlling the particle size distribution (with D50 of additive particles being 0.4 to 0.8 times the layer thickness) and composition ratio (3-10 wt% additives). These parameter changes enable the layer to maintain mechanical integrity at elevated temperatures while preserving ion conductivity, thus allowing thinner designs without sacrificing safety.
2Reliability
If additive particles are added to the solid electrolyte layer to prevent short-circuiting, then safety is improved, but ion conductivity may be reduced
Solution Approach 1:
The additive particles are distributed locally within the solid electrolyte layer at optimized concentrations (3-10 wt%) and size ratios (D50 of additives being 0.4 to 0.8 times the layer thickness). This local quality approach ensures that the additives provide structural support and short-circuit prevention where needed, while maintaining sufficient pathways for lithium ion conduction, thus balancing safety and ion conductivity.
3Stability of the object's composition
If the ratio of additive particle diameter to layer thickness is increased to improve short-circuit prevention, then structural stability is improved, but manufacturing precision requirements increase
Solution Approach 1:
The invention defines a specific parameter range for the ratio of additive particle D50 to layer thickness (0.4 to 0.8), which optimizes the balance between structural stability and manufacturing feasibility. This parameter specification provides clear manufacturing guidelines while ensuring adequate thermal stability, reducing the burden on manufacturing precision compared to more restrictive ratios.
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 solution effectively inhibits internal short-circuiting during improper use by preventing contact between the electrode layers, as demonstrated by the absence of short-circuiting in heating tests and maintained lithium ion conductivity, with direct current resistance values comparable to baseline batteries.
Implementation Method 1
additive particles that have a melting point of 700° C. or higher
Implementation Method 2
improving ion conductivity by mixing α-alumina having an average particle diameter of 10 μm or less with a sulfide solid electrolyte
Data Source
AI summary
An all-solid-state battery able to inhibit internal short-circuiting that occurs in the case of a rise in battery temperature during improper use, etc., of the all-solid-state battery is provided. The all-solid-state battery (100) has a positive electrode active material layer (10), a solid electrolyte layer (20) and a negative electrode active material layer (30) in that order, and the solid electrolyte layer (20) has solid electrolyte particles (14) and additive particles (22). The additive particles have a melting point of 700° C. or higher and are electrochemically inert. The ratio of the median diameter (D50) of the additive particles to the thickness of the solid electrolyte layer (20) is 0.4 to 0.8.