Cellulose Derivative Binder for All-Solid-State Battery
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Solution Overview
Problem
All-solid-state secondary batteries face issues with microgel formation due to strong hydrophobicity of cellulose polymers, leading to electrode defects and reduced electrical performance, especially when using traditional binder compositions without sufficient lithium ion transfer paths.
Innovation Solution
A cellulose derivative composition with multi-substituted monovalent metal ions, such as sodium and lithium, is used to suppress hydrophobicity and enhance solubility, providing a lithium ion transfer path through the binder, even in the absence of an electrolyte, thereby reducing microgel formation and improving conductive properties.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If traditional binder compositions are used, then manufacturing simplicity is maintained, but microgel formation occurs due to strong hydrophobicity of cellulose polymers, leading to electrode defects and reduced electrical performance
Solution Approach 1:
The patent changes the chemical parameters of the cellulose polymer by introducing metal ion substituents (sodium, lithium, potassium, rubidium, or cesium) at positions 2, 3, and/or 6 of the glucose unit. This parameter change modifies the hydrophobicity of the cellulose, suppressing microgel formation while maintaining binder functionality. The metal ion substitution transforms the chemical properties to reduce harmful microgel aggregation.
Solution Approach 2:
The patent creates a composite binder material by combining cellulose polymer with multiple metal ion substituents. This composite structure integrates the mechanical binding properties of cellulose with the hydrophilic characteristics introduced by metal ions, achieving both defect reduction and electrical performance improvement without sacrificing manufacturing simplicity.
2Strength
If cellulose polymer with strong hydrophobicity is used, then binder strength is maintained, but solubility decreases and microgel formation increases, reducing electrode quality
Solution Approach 1:
The patent modifies the hydrophobicity parameter of cellulose by substituting metal ions at specific positions (2, 3, and/or 6) of the glucose unit. This parameter change increases solubility by introducing hydrophilic metal ion groups while preserving the structural integrity and binding strength of the cellulose polymer backbone.
3Reliability
If no electrolyte is present in the electrode, then all-solid-state battery stability is improved, but lithium ion transfer paths are insufficient, reducing electrochemical performance
Solution Approach 1:
The patent makes the binder material multi-functional by incorporating metal ion substituents that provide both mechanical binding and lithium ion conduction pathways. The binder now serves dual purposes: structural support and ion transport, eliminating the need for separate electrolyte components while maintaining battery stability and enabling sufficient lithium ion transfer.
Solution Approach 2:
The metal ion-substituted cellulose acts as an intermediary material that facilitates lithium ion transfer between electrode particles. The metal ions (particularly lithium ions) in the binder structure create conductive pathways that mediate ion transport, replacing the traditional electrolyte function while maintaining the all-solid-state configuration.
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 cellulose derivative composition effectively reduces microgel formation, lowers interfacial resistance, and enhances electrochemical performance by facilitating fast lithium ion transfer, resulting in improved electrical properties and stability of all-solid-state secondary batteries.
Implementation Method 1
A cellulose derivative composition with multi-substituted monovalent metal ions, such as sodium and lithium, is used to suppress hydrophobicity and enhance solubility
Implementation Method 2
providing a lithium ion transfer path through the binder, even in the absence of an electrolyte, thereby reducing microgel formation and improving conductive properties
Data Source
AI summary
Provided is a cellulose derivative composition for an all-solid-state secondary battery binder including a compound represented by Formula 1 below according to the inventive concept.In Formula 1, R1, R1′, R2, R2′, R3, and R3′ are each independently any one among a carboxymethyl group, a sulfur substituent, or a phosphorus substituent, in which a monovalent metal is substituted or hydrogen, wherein R1, R2, and R3 is —CH2COOX, , SO3X, —PO3X or —PO3X2 where X may be any one among sodium (Na), potassium (K), rubidium (Rb), or cesium (Cs). R1′, R2′, and R3′ is —CH2COOY, —SO3Y, —PO3Y or —PO3Y2 where Y may be lithium (Li).