Composite Binder System for Lithium-Ion Electrode Slurry Stability
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Solution Overview
Problem
Lithium-ion secondary battery electrode mixtures face issues with gelling of the slurry and insufficient binding capacity between the electrode active material and the current collector, leading to potential separation and reduced battery performance over time.
Innovation Solution
An electrode mixture comprising a binder composition of a first copolymer of vinylidene fluoride and a polar group-containing compound, and a second copolymer of vinylidene fluoride and chlorotrifluoroethylene, with a lithium metal oxide having a pH of at least 10.5, is used to maintain high binding capacity and prevent gelling.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a vinylidene fluoride polymer is used as a binder, then the slurry can be produced, but gelling of the slurry occurs and binding capacity becomes insufficient
Solution Approach 1:
The patent uses a composite binder system comprising both polyvinylidene fluoride and a copolymer of vinylidene fluoride and chlorotrifluoroethylene. This composite material approach combines the advantages of both polymers: PVDF provides stable slurry characteristics while the VDF-CTFE copolymer enhances binding capacity to the current collector, thereby resolving the contradiction between slurry stability and binding strength.
2Stability of the object's composition
If a binder composition is used to suppress gelling, then slurry stability is improved, but binding capacity between electrode active material and current collector becomes insufficient
Solution Approach 1:
The patent employs a composite binder system comprising both polyvinylidene fluoride and a copolymer of vinylidene fluoride and chlorotrifluoroethylene. This composite material approach combines the advantages of both polymers: PVDF provides stable slurry characteristics while the VDF-CTFE copolymer enhances binding capacity to the current collector, thereby resolving the contradiction between slurry stability and binding strength.
3Productivity
If time elapses since slurry production, then coating process can be completed, but binding capacity decreases over time
Solution Approach 1:
The binder composition is specifically formulated before slurry production to ensure long-term stability. The copolymer of vinylidene fluoride and chlorotrifluoroethylene is incorporated in advance to maintain binding capacity over extended periods, allowing the slurry to be stored and applied over time without significant degradation of adhesion properties.
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 solution effectively suppresses gelling of the electrode mixture slurry and maintains a high binding capacity between the electrode active material and the current collector, even after an extended period, enhancing the stability and performance of lithium-ion secondary batteries.
Implementation Method 1
a binder composition for binding the electrode active material to the current collector
Implementation Method 2
the pH of water when the lithium metal oxide is extracted with water is not less than 10.5
Data Source
AI summary
To provide an electrode mixture that suppresses gelling of an electrode mixture slurry and maintains a high binding capacity between an electrode active material and a current collector even after an extended period of time has elapsed since an electrode mixture slurry was produced. The electrode mixture includes: a binder composition—containing a first copolymer of vinylidene fluoride and a polar group-containing compound; and a second copolymer of vinylidene fluoride and chlorotrifluoroethylene—; and an electrode active material of lithium oxide having a pH of water when extracted with water of not less than 10.5.