Modified PVdF Binder for High-Strength Conductive Electrodes
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Solution Overview
Problem
Lithium-ion secondary batteries face challenges with electrode stability, conductivity, and capacity due to the limitations of existing binders and conductive additives, leading to uneven reactions and high resistance, which hinder performance improvements.
Innovation Solution
A method is developed to modify the poly(vinylidene fluoride) structure in the electrode by eliminating hydrogen fluoride to form a polyene or aromatic ring structure, enhancing interaction with graphene and carbon materials, and using a reducing agent to reduce the polymer and carbon materials, thereby improving bonding strength and conductivity.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Strength
If PVdF is used as a binder to stabilize electrode shape, then electrode strength is improved, but electrode conductivity deteriorates due to insulator properties of binder materials
Solution Approach 1:
The patent combines PVdF binder with carbon black conductive additive in a specific configuration where carbon black particles are distributed within the PVdF matrix. This merging of insulating binder and conductive additive creates a composite structure that simultaneously provides mechanical strength from PVdF and electrical conductivity from carbon black, resolving the contradiction between electrode strength and conductivity.
Solution Approach 2:
The invention uses a composite material system consisting of PVdF polymer matrix and carbon black particles. This composite structure allows the binder to provide mechanical stability while the conductive additive embedded within provides electrical pathways, achieving both strong bonding and good conductivity that neither material could provide alone.
2Quantity of substance
If active material layer is made thick for high capacity, then capacity is improved, but reaction uniformity deteriorates due to various ohm resistances
Solution Approach 1:
The patent applies local quality by creating a heterogeneous structure where carbon black particles are distributed throughout the active material layer to provide localized conductive pathways. This ensures that even in thick electrodes, electrical conductivity and reaction uniformity are maintained in local regions, allowing the entire thick layer to participate effectively in electrochemical reactions.
3Reliability
If carbon black with small particle diameter is used to secure conductivity, then electrode conductivity is improved, but binding force deteriorates
Solution Approach 1:
The invention merges carbon black conductive additive with PVdF binder in a synergistic configuration where carbon black particles provide conductivity while PVdF provides binding force. The specific arrangement allows carbon black to form conductive networks without compromising the mechanical bonding provided by the polymer matrix, achieving both high conductivity and strong binding.
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 modified electrode structure achieves higher electrode strength, reduced resistance, and improved cycle performance, leading to increased capacity and efficient charge/discharge characteristics.
Implementation Method 1
using a reducing agent to reduce the polymer and carbon materials
Implementation Method 2
enhancing interaction with graphene and carbon materials
Data Source
AI summary
An electrode improved for achieving a storage battery having both a high electrode strength and favorable electrode conductivity is provided. The electrode includes graphene and a modified polymer in an active material layer or includes a layer substantially formed of carbon particles and an active material layer including a modified polymer over a current collector. The modified polymer has a poly(vinylidene fluoride) structure and partly has a polyene structure or an aromatic ring structure. The polyene structure or the aromatic ring structure is sandwiched between poly(vinylidene fluoride) structures.