Cross-linked Binder All-solid Battery Adhesion
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Solution Overview
Problem
All-solid batteries using sulfide-based solid electrolytes face issues with adhesion between the electrode and electrolyte layers due to expansion and contraction during charging and discharging, leading to interface resistance and potential internal short-circuits from lithium dendrite formation.
Innovation Solution
The use of cross-linked binders in both the positive and negative electrodes, along with a second binder for enhanced adhesion to the current collector, and a non-polar binder for the electrolyte layer, which includes sulfur as a cross-linking agent and specific sulfide-based materials like lithium sulfide and phosphorus sulfide, to maintain interface stability and prevent dendrite growth.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Use of energy by moving object
If a sulfide-based solid electrolyte is used to achieve high ion conductivity, then ion conductivity is improved, but adhesion between electrode and electrolyte layers deteriorates due to expansion and contraction during charging and discharging
Solution Approach 1:
The binder undergoes cross-linking transformation to change its physical and chemical properties, transitioning from a linear polymer structure to a three-dimensional network structure. This parameter change enables the binder to maintain both flexibility and adhesion strength, resolving the contradiction between ion conductivity and interfacial adhesion
Solution Approach 2:
The electrode structure is designed as a composite material system combining cross-linked binder, active material particles, and solid electrolyte. The cross-linked binder forms a resilient matrix that holds active material particles while maintaining strong adhesion to the solid electrolyte layer, solving the adhesion problem without compromising ion conductivity
2Ease of manufacture
If conventional binders are used in electrodes, then ease of manufacture is improved, but adhesion stability during charging and discharging deteriorates leading to interface resistance
Solution Approach 1:
The binder is pre-cross-linked before electrode assembly to establish a stable three-dimensional network structure in advance. This preliminary action ensures that the binder possesses sufficient adhesion strength and dimensional stability before contacting the solid electrolyte, preventing interface resistance formation during subsequent charging and discharging cycles
Solution Approach 2:
The binder's molecular structure is transformed through cross-linking from a linear configuration to a three-dimensional network, fundamentally changing its mechanical properties. This parameter change provides the binder with enhanced adhesion stability and resistance to expansion-contraction stresses while maintaining ease of manufacture through established cross-linking methodologies
3Reliability
If adhesion between electrode and electrolyte layers is maintained, then interface resistance is reduced, but lithium dendrite formation may still occur due to low overvoltage of reduction reaction
Solution Approach 1:
The cross-linking degree and network density of the binder are optimized to change its mechanical properties, creating a dual-function binder that simultaneously maintains strong interfacial adhesion and provides physical barriers against dendrite propagation. The controlled parameter changes in binder structure address both adhesion and dendrite prevention requirements
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 enhances the mechanical properties of the electrodes, maintains adhesion between the electrode and electrolyte layers, and prevents internal short-circuits, resulting in improved cycle characteristics and charging efficiency of the all-solid battery.
Implementation Method 1
at least one binder of the positive electrode and the negative electrode is cross-linked by a cross-linking agent
Implementation Method 2
a sulfide-based, i.e., a sulfide-containing, solid electrolyte having high ion conductivity
Data Source
AI summary
An all-solid battery including a positive electrode including a binder, a negative electrode including a binder, and an electrolyte layer disposed between the positive electrode and the negative electrode and including a solid electrolyte, wherein at least one binder of the positive electrode and the negative electrode is cross-linked by a cross-linking agent.