Solid-State Battery Electrode Thickness Ratio for Dendrite Suppression
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Solution Overview
Problem
All solid-state batteries face challenges in achieving excellent output characteristics and cycle-life characteristics due to lithium dendrite growth and irreversible capacity issues, particularly when using lithium metal as a negative electrode.
Innovation Solution
The battery design includes a negative electrode with a current collector and a negative electrode layer, a solid electrolyte layer with a specific thickness ratio (1.0≤b/a≤6.0) between the negative electrode layer and the solid electrolyte layer, and a lithium deposition layer, utilizing a sulfide-based solid electrolyte and a binder comprising butadiene-based rubber and cellulose-based compounds to suppress lithium dendrite growth and enhance electrical conductivity.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Use of energy by moving object
If lithium metal is used as a negative electrode to increase energy density, then energy density is improved, but lithium dendrite growth and volume expansion occur causing safety issues and irreversible capacity loss
Solution Approach 1:
The patent changes the physical state parameter of the electrolyte from liquid to solid, which fundamentally alters the interface properties between electrode and electrolyte. This parameter change suppresses lithium dendrite growth while maintaining high energy density, resolving the contradiction between energy density and cycle-life characteristics
Solution Approach 2:
The patent employs composite material structures including solid electrolyte layers combined with specific negative electrode materials. This composite approach enables simultaneous achievement of high energy density and improved cycle stability by combining the advantages of different materials while mitigating their individual disadvantages
2Use of energy by moving object
If lithium metal is used as a negative electrode, then energy density is improved, but volume expansion occurs during charging and discharging
Solution Approach 1:
The patent changes the electrolyte state from liquid to solid, which constrains volume expansion during lithium insertion and extraction. This parameter change allows lithium metal to be used for high energy density while the solid electrolyte prevents harmful volume changes, resolving the contradiction between energy density and volume stability
3Reliability
If lithium is deposited on a negative current collector without using lithium metal, then safety is improved, but power characteristics deteriorate and short-circuits occur
Solution Approach 1:
The patent changes the electrolyte from liquid to solid state, which enables safe lithium deposition on current collectors without the harmful effects of liquid electrolyte leakage. This parameter change improves safety while the solid electrolyte's unique properties maintain good power characteristics, resolving the contradiction between safety and power
4Reliability
If the solid electrolyte layer thickness is increased to suppress lithium dendrite growth, then cycle-life characteristics are improved, but output characteristics may deteriorate due to increased resistance
Solution Approach 1:
The patent changes the material composition and physical state parameters of the solid electrolyte, which enables achieving both thin film morphology and high ionic conductivity. This parameter change allows the solid electrolyte to suppress lithium dendrite growth while maintaining low resistance, resolving the contradiction between cycle-life characteristics and output characteristics
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 effectively suppresses lithium dendrite growth, improves cycle-life characteristics, and enhances output characteristics by maintaining capacity retention and reducing electrical resistance.
Implementation Method 1
the negative electrode layer thickness (a) and the solid electrolyte layer thickness (b) have the relationship expressed in Equation 1... effectively suppresses lithium dendrite growth
Implementation Method 2
The solid electrolyte included in the solid electrolyte layer may be a sulfide-based solid electrolyte... enhances output characteristics by maintaining capacity retention and reducing electrical resistance
Data Source
AI summary
The present invention relates an all solid-state battery, the all solid-state battery comprising: a current collecting body; a negative electrode comprising a negative electrode layer disposed on one surface of the current collecting body; a positive electrode; and a solid electrolyte layer located between the negative electrode and positive electrode, wherein the negative electrode layer thickness (a) and solid electrolyte layer thickness (b) have the relationship expressed in formula 1.1.0≤b/a≤6.0.[formula 1]