Polymer Electrolyte Composition for Lithium Battery Solid Phase Stability
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Solution Overview
Problem
Rechargeable lithium batteries require high energy density and safety, with existing polymer electrolytes facing challenges in achieving both high ion conductivity and electrochemical stability at room temperature, particularly in maintaining a solid phase for effective battery operation.
Innovation Solution
A polymer composition comprising methylmethacrylate, acrylonitrile, or their copolymers with ethylene oxide, combined with lithium salts, is developed to provide a binder or electrolyte for lithium batteries, offering improved ion conductivity and electrochemical stability, with specific weight ratios and molecular weights optimizing the physical phase for solid functionality.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Stability of the object's composition
If polymer electrolyte is used to maintain solid phase, then structural stability is improved, but ion conductivity deteriorates
Solution Approach 1:
The composite of PAN and PEO creates a synergistic structure where PAN provides structural stability and solid phase maintenance, while PEO contributes ion conductivity through its ether oxygen atoms that coordinate with lithium ions. This composite approach allows the electrolyte to maintain solid phase stability while achieving adequate ion conductivity.
Solution Approach 2:
The patent specifies PEO molecular weight between 40,000 and 600,000 and PAN:PEO weight ratio between 1:4 and 4:1 to optimize the balance between solid phase stability and ion conductivity. These parameter optimizations ensure the electrolyte remains solid at room temperature while maintaining sufficient ionic transport capability.
2Use of energy by moving object
If high energy density is required for portable devices, then power source performance is improved, but battery size and weight constraints worsen
Solution Approach 1:
The patent optimizes the molecular weight of PEO (40,000 to 600,000) and the composition ratio of PAN to PEO (1:4 to 4:1) to achieve high energy density in a compact form. By controlling these parameters, the battery can deliver high power output while maintaining lightweight and small form factor suitable for portable electronic devices.
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 polymer composition achieves room temperature ion conductivity of 1×10−7 S/cm to 1.7×10−4 S/cm, ensuring electrochemical stability and long cycle life, while maintaining a solid phase suitable for use as both a binder and electrolyte, enhancing the performance and safety of rechargeable lithium batteries.
Implementation Method 1
The polymer composition has room temperature ion conductivity of about 1×10−7 S/cm to about 1.7×10−4 S/cm
Implementation Method 2
polymerizing a first monomer selected from methylmethacrylate (MMA), acrylonitrile (AN), or a combination thereof, and a second monomer of ethylene oxide in accordance with radical polymerization to provide a polymer
Data Source
AI summary
A polymer composition for a rechargeable lithium battery including a polymer of a first monomer selected from methylmethacrylate (MMA), acrylonitrile (AN), or a combination thereof, and a second monomer of ethylene oxide (EO), as well as a lithium salt.