Electrode Primer Layer Composition for Conductivity and Adhesion
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Solution Overview
Problem
Current electrochemical apparatuses face challenges in enhancing both conductivity and adhesion performance due to the low conductivity of primer layers, which affects rate and cycling performance, as increasing the conductive agent proportion decreases binder proportion and adhesion utilization.
Innovation Solution
An electrochemical apparatus with a first layer between the current collector and active material layer, containing a conductive agent with a specific surface area of 60 m2/g to 1500 m2/g, and a binder with a weight-average molecular weight of 10,000 to 500,000, optimizing the mass percentage and thickness to balance conductivity and adhesion.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If the proportion of conductive agent in the primer layer is increased to enhance conductivity, then the conductivity of the primer layer is improved, but the proportion of binder decreases, adversely affecting adhesion performance
Solution Approach 1:
The patent changes the particle size parameter of the conductive agent, specifically using ultrafine conductive agents with D50 of 0.5 μm or less. This parameter change allows achieving high conductivity with lower conductive agent content (5-20 mass%), thereby maintaining adhesion performance while improving conductivity. The ultrafine particles provide larger surface area for conductive network formation, resolving the contradiction between conductivity and adhesion.
Solution Approach 2:
The patent creates a composite primer layer structure comprising ultrafine conductive agents, binder, and optionally inorganic particles. This composite material approach allows synergistic effects where ultrafine conductive particles form conductive networks while binder maintains adhesion, and inorganic particles provide additional support. The composite structure enables simultaneous achievement of high conductivity and adhesion performance.
2Strength
If the proportion of binder in the primer layer is increased to improve adhesion, then the adhesion performance is enhanced, but the conductivity of the primer layer decreases
Solution Approach 1:
The patent changes the particle size parameter of the conductive agent to ultrafine scale (D50 ≤ 0.5 μm), which fundamentally alters the conductive network formation mechanism. This allows achieving high conductivity with reduced conductive agent content, thereby enabling increased binder content (5-30 mass%) for improved adhesion without sacrificing conductivity. The ultrafine particles efficiently form conductive pathways at lower concentrations.
3Strength
If the thickness of the primer layer is increased to improve adhesion, then the adhesion force between current collector and active material layer is enhanced, but the electronic resistance of the electrode plate increases
Solution Approach 1:
The patent changes the particle size parameter of the conductive agent to ultrafine scale, which fundamentally improves conductivity per unit thickness. This allows using thinner primer layers (5-20 μm) that provide sufficient adhesion while maintaining low electronic resistance. The ultrafine particles create more efficient conductive networks in thinner configurations compared to conventional particle sizes.
4Productivity
If the proportion of conductive agent in the primer layer is increased to improve rate performance, then the rate performance is enhanced, but the cycling performance deteriorates due to decreased binder proportion
Solution Approach 1:
The patent changes the particle size parameter of the conductive agent to ultrafine scale (D50 ≤ 0.5 μm), which enables achieving high rate performance with lower conductive agent content. This optimized composition (5-20 mass% conductive agent, 5-30 mass% binder) maintains excellent adhesion for good cycling performance while providing sufficient conductivity for high rate performance. The ultrafine particles efficiently form conductive networks that support fast charge-discharge rates.
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
This configuration improves the conductive connectivity, reduces electronic resistance, and enhances both rate and cycling performance of the electrochemical apparatus while maintaining energy density.
Implementation Method 1
the conductive agent having a large specific surface area increases a quantity of conductive network paths constructed per unit area, thereby achieving a better conductive connectivity, reducing electronic resistance
Implementation Method 2
a primer layer is usually provided between a current collector and an active material layer to enhance an adhesion force between the current collector and the active material layer
Data Source
AI summary
An electrochemical apparatus includes an electrode plate, where the electrode plate includes a current collector, a first layer, and a second layer. The first layer includes a conductive agent, where the conductive agent has a specific surface area (BET) of 60 m2/g to 1500 m2/g. The second layer includes an active material. The first layer is provided between the current collector and the second layer. The conductive agent having a large specific surface area increases the quantity of conductive network paths constructed per unit area, thereby achieving a better conductive connectivity, reducing electronic resistance of the electrode plate, and improving rate performance and cycling performance of the electrochemical apparatus.