Electrochemical Functional Layer Polymer for Low Volume Expansion
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Solution Overview
Problem
Conventional polymer materials in electrochemical devices lead to increased water retention and volume expansion due to reactions between water and electrolyte solutions, causing gas evolution and structural issues.
Innovation Solution
A composition for an electrochemical device functional layer incorporating a solvent and a polymer with a specific oxide structure-containing monomer unit, having a number-average molecular weight between 5,000 and 15,000, which reduces water absorption and gas evolution, thereby inhibiting volume expansion and enhancing peel strength.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Strength
If conventional polymer materials are used in functional layers, then binding capability is achieved, but water absorption increases leading to volume expansion
Solution Approach 1:
The patent changes the chemical structure parameters of the polymer by introducing oxide structure-containing monomer units (formula I) with specific R1 groups (ethylene, propylene, or phenylethylene) and controlling the number n (2-30). This structural modification reduces water absorption while maintaining binding capability. Additionally, the number-average molecular weight is optimized to 5,000-15,000, which further controls water retention and prevents volume expansion.
2Ease of manufacture
If conventional polymer materials are used in functional layers, then functional layer formation is achieved, but gas evolution occurs due to water-electrolyte reaction
Solution Approach 1:
The patent modifies the chemical composition parameters of the polymer by incorporating oxide structure-containing monomer units with specific structures (formula I). This chemical modification reduces the polymer's affinity for water, thereby preventing water-electrolyte reactions that cause gas evolution, while still allowing functional layer formation.
3Volume of stationary object
If polymer with lower molecular weight is used, then water absorption is reduced, but binding strength decreases
Solution Approach 1:
The patent optimizes the number-average molecular weight parameter to a specific range (5,000-15,000), which balances water absorption and binding strength. Additionally, the chemical structure is modified by introducing oxide structure-containing monomer units with specific R1 groups and n values, which enhance binding capability through improved adhesion properties while controlling water absorption.
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 proposed solution effectively minimizes volume expansion and improves the peel strength of the functional layer, leading to enhanced performance and stability in electrochemical devices.
Implementation Method 1
an increased amount of water is held in the functional layer, and gas evolves through a reaction between water and electrolyte solution
Data Source
AI summary
Provided is a composition for an electrochemical device functional layer capable of providing an electrochemical device having low volume expansion. The composition for an electrochemical device functional layer contains a solvent and a polymer including an oxide structure-containing monomer unit. The oxide structure-containing monomer unit has a structure indicated by the following formula (I) (in formula (I), R1 represents an optionally substituted alkylene group and n is a positive integer), and the polymer has a number-average molecular weight of not less than 5,000 and not more than 15,000.