Cross-linked Polymer Binder for Lithium Battery Anodes
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Solution Overview
Problem
Lithium batteries with metallic active materials face challenges in maintaining mechanical properties and binding strength due to volume changes during charging/discharging, while existing binders either provide inadequate initial efficiency or stability.
Innovation Solution
A cross-linked polymer binder is developed by combining a polyamic acid or polyimide with a water-soluble polymer, such as polyvinyl alcohol, through an ester bond cross-linking process, enhancing both mechanical stability and initial charging/discharging efficiency.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Strength
If a polyimide binder is used, then mechanical properties and chemical resistance are improved, but initial charging/discharging efficiency decreases
Solution Approach 1:
The patent combines polyimide polymer (providing mechanical strength and chemical resistance) with conductive polymer (providing electrical conductivity and improving charging efficiency). This merging of two different polymer systems allows the binder to simultaneously achieve strong mechanical properties and high initial charging/discharging efficiency that neither polymer could provide alone.
2Productivity
If a water-soluble binder is used, then initial charging/discharging efficiency is improved, but mechanical properties and binding strength decrease
Solution Approach 1:
The patent merges water-soluble polymer (providing good initial charging efficiency and processability) with polyimide polymer (providing strong binding strength and mechanical properties). The synergistic combination allows the binder to exhibit both high initial charging/discharging efficiency and strong binding strength, resolving the trade-off between these two properties.
3Stability of the object's composition
If a binder is used for metallic active material, then volume change suppression is needed, but electrode stability decreases with existing binders
Solution Approach 1:
The patent creates a composite binder material consisting of polyimide polymer and conductive polymer in specific weight ratios (70:30 to 90:10). This composite structure provides both volume change suppression capability (from polyimide) and electrode stability (from the synergistic combination), preventing the electrode degradation issues that occur with conventional single-polymer binders.
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 new binder improves the initial capacity, lifespan characteristics, and electrode stability while suppressing volume changes, leading to enhanced performance in lithium batteries.
Implementation Method 1
the first polymer and the second polymer are cross-linked by an ester bond formed by a reaction of the first functional group and the second functional group
Implementation Method 2
heating the third composition at a temperature of about 160° C. or greater to prepare a third polymer
Data Source
AI summary
A binder includes a third polymer including a cross-linked product of a first polymer and a second polymer, wherein the first polymer includes a first functional group and is at least one selected from a polyamic acid and a polyimide, wherein the second polymer includes a second functional group and is water-soluble, and wherein the first polymer and the second polymer are cross-linked by an ester bond formed by a reaction of the first functional group and the second functional.