Amino-Rich Li-Ion Battery Binder for Alkali-Stable Electrode Adhesion
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Solution Overview
Problem
Polyacrylamide type binders used in lithium-ion batteries exhibit poor alkali resistance due to easy decomposition of amide groups under alkaline conditions, leading to instability and potential gas production.
Innovation Solution
A binder rich in free amino groups directly connected to alkyl groups, which provides strong alkali resistance and stability, and enhances bonding through hydrogen bonding, formed by a polymer containing specific repeating units derived from hydrophilic, hydrophobic, and amphiphilic monomers, and processed through Hoffman degradation or hydrolysis.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Strength
If polyacrylamide type binder with amide groups is used, then good adhesion to copper foil and hydrogen bonding capability are achieved, but alkali resistance deteriorates due to easy decomposition of amide groups under alkaline conditions
Solution Approach 1:
The patent changes the chemical structure parameter by replacing the amide group (-CONH2) with a free amino group (-NH2) directly connected to alkyl groups. This structural modification maintains the hydrogen bonding capability and adhesion properties while eliminating the susceptibility to alkaline hydrolysis that characterizes amide groups, thereby resolving the contradiction between adhesion strength and alkali resistance.
Solution Approach 2:
The binder employs a composite molecular structure combining hydrophilic groups (containing free amino groups for hydrogen bonding) with hydrophobic groups (alkyl chains for stability). This composite approach allows the molecule to simultaneously achieve strong adhesion through hydrogen bonding and high alkali resistance through the stable hydrophobic alkyl framework, preventing the decomposition issue seen in pure polyacrylamide structures.
2Strength
If polyacrylamide type binder is used, then bonding function between active material layers and substrate is achieved, but decomposition and gas production occur under alkaline conditions
Solution Approach 1:
The patent modifies the chemical composition by replacing the carbonyl-containing amide group with a simpler free amino group structure. This parameter change eliminates the carbonyl carbon that is susceptible to nucleophilic attack by hydroxide ions, thereby preventing decomposition and ammonia gas generation while preserving the hydrogen bonding capability necessary for strong bonding between active material layers and substrate.
Solution Approach 2:
The patent converts the potential harm of having nitrogen-containing groups (which can decompose to produce ammonia gas) into a benefit by using free amino groups that are chemically stable under alkaline conditions. The free amino groups maintain the desired bonding function while eliminating the harmful decomposition pathway, effectively turning a potentially problematic functional group into a stable, beneficial component.
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 binder significantly improves the peeling strength, cycle performance, and rate capability of lithium-ion batteries by forming a robust adhesive network and maintaining stability under alkaline conditions, while maintaining simplicity in preparation.
Implementation Method 1
the electronegativity of N atom in the free amino group is stronger than that of N atom in amide, which is more conducive to the formation of hydrogen bonds, thereby enhancing the bonding force
Implementation Method 2
processed through Hoffman degradation or hydrolysis
Data Source
AI summary
The present application provides a binder and a lithium-ion battery including the binder. The binder is rich in amino groups, has strong alkali resistance and is not easy to decompose. Besides, rich amino groups in the binder are prone to form hydrogen bonds, so that the binder more fully coats an active material and can enhance an acting force between the active material and a current collector, improve a peeling strength of an electrode piece, and significantly improve a cycling performance, expansion rate, and rate capability of lithium-ion batteries using the binder.