Crosslinking Aqueous Binder for Li-Ion Batteries
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Solution Overview
Problem
Current lithium-ion battery binders, such as polyvinylidene fluoride (PVDF), face issues like poor conductivity, high production costs, and insufficient flexibility, while aqueous binders like styrene-butadiene rubber (SBR)/sodium carboxymethyl cellulose and polyacrylates lack binding strength and electrode swelling prevention, especially for silicon anodes.
Innovation Solution
A crosslinking-type aqueous binder is developed using organic carboxylic group-, amino group-, or hydroxyl group-containing hydrophilic polymers and water-soluble small-molecule crosslinkers, which undergo esterification or amidation during the coating and drying process of lithium-ion battery electrode slurry, enhancing binding strength and elasticity.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Strength
If PVDF is used as a binder with NMP as dispersant, then binding capability is improved, but production cost increases and environmental requirements become more stringent
Solution Approach 1:
The patent replaces expensive PVDF binder with inexpensive natural polymer binders (carboxymethyl cellulose, starch, chitosan, gelatin, alginate) that are biodegradable and environmentally friendly. These disposable-like materials eliminate the need for costly organic solvents and complex disposal procedures, directly addressing the technical contradiction between binding capability and manufacturing ease/cost
Solution Approach 2:
The patent modifies the chemical parameters of natural polymers by introducing carboxyl groups through carboxymethylation or other chemical modifications. This parameter change enhances the binding capability of naturally inexpensive materials to match or exceed PVDF performance while maintaining the cost and environmental advantages of natural polymers
2Strength
If crosslinked structure is introduced to improve binding strength and elasticity, then electrode swelling prevention is improved, but synthesis process complexity increases
Solution Approach 1:
The patent incorporates crosslinking agents directly into the slurry preparation stage before electrode fabrication. The crosslinking reaction occurs in-situ during slurry coating and drying, eliminating the need for separate crosslinking steps. This preliminary action resolves the technical contradiction by achieving crosslinked structure formation without adding synthesis process complexity
Solution Approach 2:
The patent merges the binder preparation, slurry formation, and crosslinking processes into a single integrated workflow. The crosslinking agent is mixed with the natural polymer binder and electrode materials to form a unified slurry that undergoes crosslinking during the normal drying process, combining multiple functions into one process stream and eliminating additional synthesis steps
3Ease of manufacture
If conventional aqueous binders like SBR/CMC are used, then environmental friendliness is improved, but binding strength and electrode swelling prevention are insufficient
Solution Approach 1:
The patent creates composite binder systems by combining natural polymers (carboxymethyl cellulose, starch, chitosan, gelatin, or alginate) with crosslinking agents (epichlorohydrin, glutaraldehyde, or genipin). This composite approach merges the environmental benefits of natural polymers with the enhanced mechanical properties provided by crosslinking, simultaneously achieving both improved binding strength and environmental friendliness
Solution Approach 2:
The patent fundamentally changes the chemical parameters of conventional aqueous binders by introducing crosslinkable functional groups and forming three-dimensional crosslinked networks. This parameter transformation elevates the binding strength and swelling resistance of environmentally friendly natural polymers to levels comparable with or exceeding conventional binders, resolving the technical contradiction between environmental friendliness and binding performance
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 crosslinking-type binder improves the binding capacity and flexibility of electrodes, preventing swelling and breaking, and increases ion conduction rates, thus enhancing the electrochemical performance and cycling stability of lithium-ion batteries.
Implementation Method 1
can be crosslinked by esterification or amidation under coating and drying conditions of lithium-ion battery electrode slurry
Implementation Method 2
can be crosslinked by esterification or amidation under coating and drying conditions of lithium-ion battery electrode slurry
Implementation Method 3
have sufficient elasticity that prevents the electrode from swelling and breaking off from the current collector due to volume expansion and contraction during charging and discharging
Implementation Method 4
facilitates electron and ion transportation to reduce the impedance between the current collector and the electrode materials
Data Source
AI summary
A preparation method of a crosslinking-type aqueous binder for lithium-ion batteries. An organic carboxylic group-, amino group- or hydroxyl group-containing hydrophilic polymer, and a hydroxyl group-, amine group- or carboxyl group-containing water-soluble small-molecule crosslinker, both serve as starting materials of the aqueous binder, and can be crosslinked by esterification or amidation under coating and drying conditions of lithium-ion battery electrode slurry. The preparation method of the crosslinking-type aqueous binder is simple, without the need of modifying the current process or conditions for lithium-ion battery manufacture. The obtained electrodes have excellent binding capacity, flexibility, and elasticity.