Lithium-Ion Cathode Conductive Paste for Viscosity Stability
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Solution Overview
Problem
Conductive pastes for lithium-ion battery positive electrodes tend to experience viscosity increase and gelation, especially when containing basic substances, making them difficult to apply effectively.
Innovation Solution
A conductive paste composition including a dispersion resin, polyvinylidene fluoride, conductive carbon, and a solvent with a dehydrating agent, which inhibits the polymerization of polyvinylidene fluoride molecules and maintains a stable viscosity, even under basic conditions.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Strength
If polyvinylidene fluoride is used as a binder in conductive paste containing basic substance, then binding performance between metal oxide and collector is improved, but viscosity increases and gelation occurs during storage
Solution Approach 1:
The patent introduces a specific dispersant as an intermediary substance between the polyvinylidene fluoride binder and the basic substance. This dispersant mediates the interaction by forming a protective complex with the basic substance, preventing it from triggering unwanted reactions with the binder. The dispersant acts as a buffer that maintains compatibility between components that would otherwise be incompatible, allowing the binder to perform its binding function while the paste remains stable during storage.
2Strength
If basic substance is incorporated into conductive paste, then electrode active material binding is improved, but polymerization of polyvinylidene fluoride occurs leading to gelation
Solution Approach 1:
The patent applies preliminary anti-action by adding a dispersant before the basic substance can trigger polymerization of the polyvinylidene fluoride. The dispersant is pre-introduced into the paste formulation to preemptively neutralize or sequester the basic substance, preventing it from initiating the harmful polymerization reaction. This proactive approach stops the gelation process before it can occur, while still allowing the basic substance to fulfill its binding function.
3Ease of operation
If conductive paste has low viscosity for easy application, then applicability is improved, but storage stability decreases due to viscosity increase and gelation
Solution Approach 1:
The patent utilizes parameter changes by carefully controlling the formulation parameters of the paste, specifically the ratios and types of dispersants and binders. By adjusting these parameters, the paste maintains an optimal viscosity range that satisfies both application requirements (low enough for easy coating) and storage stability requirements (high enough to prevent gelation). The dispersant system allows the paste to exhibit non-Newtonian flow characteristics where viscosity can be tuned for application then stabilizes for storage.
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 prevents viscosity increase and gelation, ensuring an easy-to-apply consistency and improved storage stability of the conductive paste, enhancing the manufacturing process for lithium-ion battery electrodes.
Implementation Method 1
a dehydrating agent, which removes water from the conductive paste
Implementation Method 2
a conductive paste containing a conductive auxiliary agent (e.g., carbon)... conductive carbon (C)
Implementation Method 3
Polyvinylidene fluoride is useful for incorporating into such a conductive paste as a binder for binding a metal oxide and a collector
Data Source
AI summary
The present invention provides a conductive paste for positive electrodes of lithium-ion batteries and a mixture paste for positive electrodes of lithium-ion batteries that are inhibited from increasing in viscosity and gelling, and that have an easy-to-apply viscosity. The conductive paste of the present invention contains a dispersion resin (A), polyvinylidene fluoride (B), conductive carbon (C), a solvent (D), and a dehydrating agent (E).