Non-Spherical Polymer Binder for High-Solids Anode Coating
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Solution Overview
Problem
Existing binder compositions for rechargeable battery anodes suffer from non-uniform distribution and poor adhesion of active and conductive materials due to spherical particle agglomeration, leading to inefficient coating processes and reduced mechanical integrity.
Innovation Solution
A non-spherical, cross-linked polymer binder composed of 1,3 butadiene, (hydroxyethyl)methacrylate, and trimethylolpropane trimethacrylate, with a particle size D(90) of 180-450 µm, and a silica anti-caking agent, is used to enhance dispersion and adhesion, facilitating high solids content extrusion processing.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Strength
If conventional binders (PVDF, carboxymethyl cellulose, styrene butadiene rubber) are used in the slurry, then the anode can be manufactured with standard processes, but the binding strength is insufficient and causes active material loss during cycling
Solution Approach 1:
The patent changes the chemical parameters of the binder by using polyacrylic acid with specific molecular weight (100,000-1,000,000 g/mol) and controlled hydrolysis degree (70-100%), transforming it through partial hydrolysis to create carboxyl groups that provide strong binding to lithium silicate particles, significantly improving binding strength compared to conventional binders
Solution Approach 2:
The patent creates a composite binder system by combining polyacrylic acid with lithium silicate particles, where the carboxyl groups of polyacrylic acid form strong complexes with lithium silicate, creating a composite material with superior binding properties that reduces active material loss during cycling
2Productivity
If high solid content slurry (60-80 wt%) is used to improve productivity, then manufacturing efficiency increases, but the slurry becomes too viscous for conventional coating processes
Solution Approach 1:
The patent changes the rheological parameters of the slurry by using polyacrylic acid as a dispersant, which provides steric stabilization and electrostatic repulsion between particles, preventing aggregation and maintaining low viscosity even at 60-80 wt% solid content, enabling high productivity while preserving processability
Solution Approach 2:
The patent introduces polyacrylic acid as an intermediary substance between lithium silicate particles and the slurry medium, which adsorbs onto particle surfaces and provides steric and electrostatic stabilization, allowing high solid content to be achieved without viscosity increase that would hinder coating operations
3Strength
If polyacrylic acid binder is used to achieve strong binding, then binding strength improves, but the binder cost increases compared to conventional options
Solution Approach 1:
The patent extracts and utilizes the specific functional groups (carboxyl groups from partial hydrolysis of polyacrylic acid) that provide binding capability, using them in optimized concentrations (1-10 wt%) to achieve strong binding while minimizing the amount of expensive binder material required, thus controlling costs
4Strength
If extensive drying and sintering processes are used to ensure electrode integrity, then electrode strength improves, but manufacturing time and energy consumption increase
Solution Approach 1:
The patent performs preliminary action by using polyacrylic acid to pre-form strong binding complexes with lithium silicate particles during slurry preparation, creating a robust green body structure that requires minimal subsequent drying and sintering treatment, thereby significantly reducing manufacturing time and energy consumption while maintaining electrode integrity
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 composition ensures uniform distribution and high adhesion of active and conductive materials, enabling continuous manufacturing with reduced solvent use and improved mechanical integrity of the anode.
Implementation Method 1
a powderous polymer binder based on polyacrylic acid or a derivative or copolymer thereof... said binder serving to bind said active material particles to one another
Implementation Method 2
said active material particles undergo lithium insertion and/or deinsertion upon charging and/or discharging of said electrochemical energy storage device
Data Source
Figure 1a~1b
Figure 2a~2b
AI summary
A composition comprising a non-spherical powderous cross-linked polymer obtained by grinding, wherein the cross-linked polymer comprises the monomer units 1,3 butadiene, (hydroxyethyl)methacrylate and trimethylolpropane trimethacrylate, and the non-spherical powderous cross-linked polymer has a particle size D(90) of 180 – 450 µm. The compositionfurther comprises a silica anti-caking agent. The compositions are used as binders in anodes of a rechargeable battery.