Solid Electrolyte Thickness Ratio for Battery Output
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Solution Overview
Problem
Lithium ion secondary batteries with solid electrolytes face challenges in achieving high output characteristics due to limitations in ion conductivity and safety concerns related to liquid electrolyte leakage, necessitating improvements in solid electrolyte layer thickness ratios and configurations.
Innovation Solution
A lithium ion secondary battery design with a specific ratio of average thickness of the thickest to the thinnest solid electrolyte layer (1.02 ≤ tl/t2 ≤ 1.99) and controlled standard deviation (0.15 ≤ σ < 1.66 µm) to enhance charge/discharge reactions and suppress heterogeneous reactions, along with an intermediate layer to facilitate lithium ion exchange and reduce interface resistance.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If solid electrolyte is used instead of liquid electrolyte, then safety is improved, but ion conductivity deteriorates
Solution Approach 1:
The battery is divided into multiple battery units, each containing electrode assemblies with solid electrolyte layers. By segmenting the battery into multiple units with controlled thickness ratios, the invention achieves both safety through solid electrolyte usage and maintains ion conductivity through optimized layer configuration
Solution Approach 2:
The solid electrolyte layers are configured with different thicknesses in different locations (t1 and t2), creating local quality variations. The ratio control (1.005 ≤ t1/t2 ≤ 2.0) ensures that thicker regions provide safety while thinner regions maintain ion conductivity, resolving the contradiction between safety and power
2Reliability
If solid electrolyte layer thickness is increased, then safety is improved, but output characteristics deteriorate
Solution Approach 1:
Different regions of the solid electrolyte have different thicknesses (t1 and t2), allowing local optimization where thicker regions enhance safety and thinner regions maintain output characteristics. The ratio constraint ensures both objectives are met simultaneously
Solution Approach 2:
The invention changes the thickness parameter of solid electrolyte layers from uniform to variable, with specific ratio constraints (1.005 ≤ t1/t2 ≤ 2.0). This parameter optimization allows the system to achieve both high safety and high output characteristics by balancing thickness across different regions
3Ease of manufacture
If uniform solid electrolyte layer thickness is used, then manufacturing simplicity is maintained, but charge bias occurs and output characteristics deteriorate
Solution Approach 1:
The solid electrolyte layers are designed with different thicknesses (t1 and t2) in different regions, creating local quality variations that generate beneficial charge bias. This improves output characteristics while the ratio constraint (1.005 ≤ t1/t2 ≤ 2.0) maintains manufacturing feasibility
Solution Approach 2:
The invention optimizes the thickness parameter by allowing variation within a controlled ratio (1.005 ≤ t1/t2 ≤ 2.0), rather than requiring uniform thickness. This parameter change improves charge/discharge efficiency and output characteristics while remaining manufacturable
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 battery achieves improved output characteristics by optimizing charge bias and reaction rates, ensuring high performance and reliability while maintaining insulation between electrodes.
Implementation Method 1
the charge/discharge reaction in the positive electrode and the negative electrode via the solid electrolyte layer
Data Source
AI summary
The lithium ion secondary battery wherein at least one positive electrode layer including a positive electrode active material layer and at least one negative electrode layer including a negative electrode active material layer are laminated in sequence with at least one solid electrolyte layer interposed therebetween, wherein a ratio t1/t2 of an average thickness t1 of the thickest solid electrolyte layer to an average thickness t2 of the thinnest solid electrolyte layer satisfies 1.02 ≤ t1/t2 ≤ 1.99 when an average thickness of each of the solid electrolyte layer is defined as t.