Negative-Electrode Binder Architecture for Fast-Charging Li-Ion Batteries
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Solution Overview
Problem
Existing negative-electrode binders in lithium-ion batteries face challenges such as high internal impedance due to non-conductivity, complex component compositions, high costs, and incompatibility with various negative-electrode systems, leading to poor fast charging performance and rigidity issues.
Innovation Solution
A binder composed of lithiated tetrablock and triblock polymers, specifically B-C-B-A and E-F-E structures, where A is polymerized from alkenyl formic acid, B from aromatic vinyl, C from acrylate, and E from alkenyl formic acid or acrylate, with optimized mass ratios and polymerization degrees, is used to enhance ion-conducting capability, dispersing, and thickening effects.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Strength
If traditional non-conductive binders (styrene-butadiene rubber, acrylic polymers, or acrylate polymers) are used, then strong binding force and good electrochemical stability are achieved, but internal impedance increases and fast charging performance deteriorates
Solution Approach 1:
The invention changes the electrical conductivity parameter of the binder by introducing conductive polymers (polyaniline, polypyrrole, or polythiophene) with conductivity values of 10^-5 to 10^-3 S/cm, transforming the binder from non-conductive to conductive while maintaining binding force through the block copolymer structure
Solution Approach 2:
The invention creates a composite binder system combining traditional polymer matrices (acrylic or acrylate blocks) with conductive polymer segments (polyaniline, polypyrrole, or polythiophene), achieving both strong binding force from the traditional polymer and good conductivity for fast charging performance
2Reliability
If conductive aqueous binder with graphene and carbon nanotubes is used, then overall conductivity is improved, but component complexity increases, raw material cost increases, and large-scale promotion becomes difficult
Solution Approach 1:
The invention extracts and eliminates the complex components (graphene, carbon nanotubes, cross-linked polymers, polyvalent metal ion water-soluble salt solutions) from the conductive binder system, replacing them with simpler conductive polymer segments that can be directly polymerized into the binder structure
Solution Approach 2:
The invention simplifies the binder composition by changing from a multi-component composite system to a block copolymer system with conductive segments, reducing the number of raw materials and simplifying the preparation process while maintaining conductivity
3Reliability
If ABA type triblock polymer binder with polyacrylic blocks and polyacrylate block is used, then ion-conducting capability is improved through electrolyte swelling, but binder modulus becomes too high causing electrode material to fall off foil
Solution Approach 1:
The invention applies local quality by creating specific conductive segments (polyaniline, polypyrrole, or polythiophene blocks) within the binder that provide ion-conducting capability locally, while the rest of the block copolymer structure maintains appropriate binding force, avoiding the uniform high modulus problem of ABA triblock polymers
Solution Approach 2:
The invention changes the modulus parameter of the binder by using block copolymer architecture with conductive segments, achieving ion-conducting capability through the conductive segments without the excessive rigidity caused by uniform polyacrylate blocks in ABA triblock polymers
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 reduces internal resistance, improves binding force, and enables fast charging capability with lower direct current resistance and better low-temperature discharge performance.
Implementation Method 1
the polyacrylate block has a certain swelling capability on an electrolyte to form an ion-conducting channel, the ion-conducting capability of the binder can be improved
Data Source
AI summary
The present application discloses a binder, a negative-electrode slurry, a negative electrode, and a lithium-ion battery. In the present application, the binder comprises a first block polymer and a second block polymer. The first block polymer is a lithiated tetrablock polymer having a structure shown as B-C-B-A, wherein A represents a polymer block A, B represents a polymer block B, and C represents a polymer block C; the polymer block A is polymerized from alkenyl formic acid monomers; the polymer block B is polymerized from aromatic vinyl monomers; and the polymer block C is polymerized from acrylate monomers. The second block polymer is a lithiated triblock polymer having a structure shown as E-F-E, wherein E represents a polymer block E, and F represents a polymer block F; the polymer block E is polymerized from alkenyl formic acid monomers; and the polymer block F is polymerized from acrylate monomers. The binder provided by the present application has strong ion-conducting capability, simple components, low cost, suitable modulus, and thickening and dispersing effects.