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 between them, where the thickness ratio of the solid electrolyte layer to the negative electrode layer is within a specific range (1.0≤b/a≤6.0), and the negative electrode layer is composed of a carbon-based material, metal particles, and a binder, which suppresses lithium dendrite growth and improves 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 electrochemical environment at the negative electrode. This solid state prevents lithium dendrite formation while maintaining high energy density, resolving the contradiction between energy density improvement and reliability maintenance
Solution Approach 2:
The patent employs a composite negative electrode structure combining carbon-based materials with metal particles (such as lithium, sodium, or their alloys). This composite approach enables high energy density through metal particle capacity while the carbon matrix prevents dendrite growth and provides structural stability, thus improving both energy density and cycle-life characteristics
2Quantity of substance
If lithium metal is used as a negative electrode, then capacity is improved, but volume expansion occurs during charging and discharging
Solution Approach 1:
The patent utilizes a solid electrolyte layer that acts as a constrained environment for lithium ion insertion and extraction. This solid film structure accommodates volume changes through ion transport while maintaining overall structural integrity, preventing the severe volume expansion that would occur with bulk lithium metal
Solution Approach 2:
The composite negative electrode with carbon-based materials and metal particles provides a matrix that accommodates volume expansion. The carbon material serves as a buffer that absorbs dimensional changes during cycling, allowing high capacity metal particles to be integrated without suffering from volume expansion issues
3Reliability
If deposition of lithium on negative current collector is used without lithium metal, then safety is improved, but power characteristics deteriorate and short-circuits occur
Solution Approach 1:
The patent creates a composite negative electrode combining carbon-based materials (which provide safety by preventing dendrites) with metal particles (which provide high power characteristics through fast ion transport). This composite structure simultaneously achieves improved safety and maintained power characteristics, resolving the contradiction between these two parameters
4Reliability
If solid electrolyte layer thickness is increased to suppress dendrites, then reliability is improved, but internal resistance increases reducing output characteristics
Solution Approach 1:
The patent optimizes the thickness parameter of the solid electrolyte layer to a specific range that simultaneously achieves dendrite suppression and maintains low internal resistance. By precisely controlling this dimensional parameter, the patent resolves the contradiction between reliability improvement through dendrite suppression and power characteristics maintenance
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, enhances cycle-life characteristics, and improves output characteristics by maintaining capacity retention and reducing electrical resistance.
Implementation Method 1
a solid electrolyte located between the negative electrode and the positive electrode
Implementation Method 2
a negative electrode including a current collector and a negative electrode layer disposed on one surface of the current collector
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]