Organosilicone Positive Electrode Binder for High Compaction Density
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Solution Overview
Problem
Current lithium-ion battery positive electrode binders, such as PVDF, suffer from weak bonding with active materials, leading to debonding and reduced battery performance, and are prone to decomposition at high temperatures, while alternative binders like PAN and PI lack flexibility and mechanical stability.
Innovation Solution
A novel organosilicone binder is developed, capable of self-crosslinking at high temperatures, featuring a silicon-oxygen framework for flexibility and strong bonding with active materials through hydrogen and dipole-dipole interactions, and epoxy groups forming ether bonds for enhanced cohesive force.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If PVDF binder is used, then the electrode structure is maintained, but the bonding strength with active material is weak and decomposition occurs at high temperature
Solution Approach 1:
The patent changes the chemical composition parameters of the binder by introducing organosilicone polymers with specific functional groups (cyano groups, hydroxyl groups, epoxy groups) to achieve both high bonding strength and thermal stability, resolving the contradiction between maintaining reliable bonding and preventing high-temperature decomposition
Solution Approach 2:
The patent creates a composite binder system combining organosilicone polymer chains with multiple functional groups that work synergistically: cyano groups provide polar interactions for strong bonding, hydroxyl groups enable hydrogen bonding, and epoxy groups contribute to crosslinking and thermal stability, thereby achieving both strong bonding and high-temperature resistance
2Reliability
If PAN binder is used, then bonding strength is improved, but flexibility is insufficient resulting in low compaction density
Solution Approach 1:
The patent modifies the binder's mechanical parameters by selecting organosilicone polymers with appropriate molecular weight, glass transition temperature, and chain flexibility to achieve both strong bonding and high flexibility, enabling high compaction density while maintaining bonding strength
Solution Approach 2:
The organosilicone binder forms a flexible matrix that can accommodate electrode plate deformation during cycling and cold-pressing, maintaining contact between active material particles and current collector, thereby achieving high compaction density without sacrificing bonding strength
3Temperature
If PI binder is used, then thermal stability is achieved, but mechanical performance is inferior due to insufficient flexibility
Solution Approach 1:
The patent develops a composite organosilicone binder incorporating multiple functional groups (cyano, hydroxyl, epoxy) within the same polymer system to simultaneously achieve thermal stability through strong intermolecular interactions and mechanical flexibility through the polymer chain structure, resolving the contradiction between thermal stability and mechanical performance
4Ease of manufacture
If binder with high flexibility is used, then compaction density is maintained, but bonding strength may be reduced
Solution Approach 1:
The patent optimizes the molecular weight and glass transition temperature parameters of the organosilicone binder to achieve the right balance: low enough Tg for flexibility and high enough molecular weight for bonding strength, while incorporating functional groups that enhance adhesion without compromising flexibility
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 organosilicone binder achieves high compaction density and energy density, improves structural stability, and extends cycle performance by maintaining bonding strength and reducing electrode plate rebound.
Implementation Method 1
a silicon-oxygen framework endows the binder with high flexibility to avoid the hardness and brittleness of the binder in use
Implementation Method 2
a strongly polar cyano group in a side chain of the organosilicone binder makes the organosilicone binder highly resistant to oxidation in a high-voltage system on the one hand, and on the other hand, can interact with a hydroxyl group on the surface of the positive active material to form strong hydrogen bonding
Implementation Method 3
an epoxy group in a binder molecule can also react with a hydroxyl group in an adjacent molecule and the hydroxyl group on the surface of the positive active material to form an ether bond, thereby increasing the cohesive force of the electrode plate
Implementation Method 4
can interact with a hydroxyl group on the surface of the positive active material to form strong hydrogen bonding and dipole-dipole interactions
Data Source
AI summary
A binder includes a polymer. The polymer is polymerized from at least a first monomer and a second monomer. The first monomer assumes a structure represented by Formula I, and the second monomer assumes a structure represented by Formula II:The binder has high flexibility and can effectively avoid a low compaction density caused by hardness and brittleness of the binder in use. The electrode plate prepared from the binder exhibits a strong bonding force and a strong cohesive force, thereby avoiding shedding of active material powder and debonding of a coating film from the electrode plate during cycling, avoiding drastic loss of the compaction density caused by an excessive rebound of the electrode plate, and improving cycle stability of the electrochemical device.